Thai Geoscience Journal Vol.1 No.1

ISSN 2730-2695

FIRST ISSUE THAI
GEOSCIENCE

JOURNAL

Vol.1 No.1 July-December 2020

Published By
Department of Mineral Resources

Geological Society of Thailand

Editorial Committee

Honorary Editors
Dr. Sommai Techawan Department of Mineral Resources and
Geological Society of Thailand
Mr. Niwat Maneekut Department of Mineral Resources
Mr. Montri Luengingkasoot Department of Mineral Resources

Advisory Editors
Prof. Dr. Clive Burrett Palaeontological Research and Education Centre,
Mahasarakham University, Thailand
Prof. Dr. Katsuo Sashida Mahidol University, Kanchanaburi Campus, Thailand
Prof. Dr. Nigel C. Hughes University of California, Riverside, USA
Prof. Dr. Punya Charusiri Department of Mineral Resources and
Geological Society of Thailand

Editor In Chief
Dr. Apsorn Sardsud Department of Mineral Resources, Thailand

Associate Editors
Dr. Apsorn Sardsud Department of Mineral Resources, Thailand
Prof. Dr. Clive Burrett Palaeontological Research and Education Centre,
Mahasarakham University, Thailand
Dr. Dhiti Tulyatid CCOP - Coordinating Committee for Geoscience
Programmes in East and Southeast Asia, Thailand
Mr. Jitisak Premmanee Department of Mineral Resources, Thailand
Prof. Dr. Katsuo Sashida Mahidol University, Kanchanaburi Campus, Thailand
Dr. Mallika Nillorm Department of Mineral Resources, Thailand
Prof. Dr. Montri Choowong Chulalongkorn University, Thailand
Asst. Prof. Nusara Surakotra Department of Geotechnology Faculty of Technology,
Khon Kaen University, Thailand
Dr. Seung-bae Lee Korea Institute of Geoscience and Mineral Resources, Republic of Korea
Dr. Weerachat Wiwegwin Department of Mineral Resources, Thailand

Editorial Secretary
Mineral Resources Analysis and Identification Division, Department of Mineral Resources
Mr. Inthat Chanpheng
Ms. Jeerawan Mermana
Mr. Kittichai Tongtherm
Ms. Paveena Kitbutrawat
Ms. Peeraporn Nikhomchaiprasert
Dr. Puangtong Puangkaew
Ms. Roongrawee Kingsawat
Mrs. Sasithon Saelee
Ms. Thapanee Pengtha

On the cover
1. A) Thailandium solum Kobayashi,1957 cranidia from Ko Tarutao at Ao Mo Lae (Shelly J. Wernette et al., p.72)

1.A 1.B B) Landmark Scheme of Prosaukia and Thailandium (Shelly J. Wernette et al., p.68)
2. 3 . 2. Quartzofeldspathic garnet mica schist showing foliated texture (Sirot Salyapongse et al., p.34)

3. Field photograph of the Hua Na Kham Formation and the Khao Pa Khi Limestone (Shikeki Hada et al., p.10)
4. 5. 4. ASTER regolith-landform map of the Gnaweeda Greenstone Belt, Western Australia

(Siriporn Soongpankhao, p.87)
5. Location and topography of study area, Banrai, Uthai Thani (Apsorn Sardsud et al., p.18)
Copyright © 2020 by the Department of Mineral Resources of Thailand
visit Thai Geoscience Journal website at http://www.dmr.go.th

THAI GEOSCIENCE
JOURNAL

Vol.1 No.1 (First Issue)
July-December 2020

Published By
Department of Mineral Resources and Geological Society of Thailand

Copyright © 2020 by the Department of Mineral Resources of Thailand
visit Thai Geoscience Journal website at http://www.dmr.go.th

Preface

On behalf of the Department of Mineral Resources and the Geological
Society of Thailand, it is my pleasure to support and publish the Thai Geoscience
Journal (TGJ). The Thai Geoscience Journal (TGJ) is established by cooperation
between the Department of Mineral Resources of Thailand and the Geological
Society of Thailand in order to enhance research in all the many areas of
geoscience. Thai Geoscience Journal (TGJ) continues publication from the former
Journal of the Geological Society of Thailand (GST) the last volume of which
was published in 2015. I congratulate TGJ for the First Issue to be released
in July 2020.

This TGJ publication is an international peer reviewed, open access and
online journal publishing original research articles in English and Thai that
focuses in various subjects in geosciences, geo-environments, geo-hazards, and
their related research in every area in the world. We warmly welcome all Thai
and foreign scientists, geoscience and related researchers, to publish their
valuable articles in the Journal free of charge.

We sincerely hope that this first issue will provide valuable geoscience
knowledge and information, and will inspire readers and researchers to produce
highly valued research in the future. Finally, we are pleased to invite geologists,
scientists and researchers to publish in our TGJ.

Thank you very much.



(Dr. Sommai Techawan)
Director-General of Department of Mineral Resources

President of Geological Society of Thailand
 

From the editor

Welcome to the Thai Geoscience Journal (TGJ). This an online and print-off
journal that discusses topics related to all areas of geoscience focusing on
sedimentology and geomorphology, palaeontology, quaternary geology and
environmental change, geological hazards, environmental geosciences, geophysics,
mineral and petroleum geology, tectonics and structural geology, geochemistry
and geochronology, metamorphic geology and volcanic and igneous
geology. Articles in TGJ are peer-reviewed by geoscience specialists and
academics from worldwide organizations. The success of the first issue of TGJ
clearly reveals the international cooperation of geoscience society.

As the Editor-in-Chief of the TGJ, I would like to express our sincere thanks
to authors who have chosen TGJ to publish their researches. Furthermore,
the first issue would not have been possible without the great support from
honorary editors, advisory editors, associate editors, and other editorial secretary
teams for their work supporting the success of the first issue. We hope to receive
more valuable articles from geologists, scientists, researchers, scholars, and
practitioners for publication in the next issue in January 2021.

Finally, I would like to dedicate the first issue of TGJ and express deep
condolences for the passing away of Department of Mineral Resources’ former
geologists, Dr. Sangad Bunopas (in July 2020), who is the most famous
and important Thai geologist who established Shan-Thai and Indochina
micro-continents for tectonics and the geology of Thailand and Dr. Somboon
Khosithanont (in September 2019), one of our executive advisors and one of the
authors in this first issue.

Thank you very much.


(Dr. Apsorn Sardsud)
Editor-in-Chief

Thai Geoscience Journal

Thai Geoscience Journal
Vol.1 No.1 (First Issue)
July-December 2020

ISSN 2730-2695

LIST OF CONTENTS

A remarkable end-Permian boulder bed of conglomeratic limestone Page
at Nam Nao in NE Thailand: its biostratigraphical and environmental significance 1-16
Shigeki Hada, Somboon Khosithanont and Hiroya Goto

Possible sources of elevated arsenic in surface and ground water, Amphoe Banrai, 17-26
Changwat Uthai Thani, Thailand
Apsorn Sardsud, Onuma Khamphleang and Jitisak Premmanee

Transition between the Thabsila metamorphic complex and the Lower Paleozoic 27-46
formations and their sandstone provenance, Kanchanaburi, western Thailand
Sirot Salyapongse, Praipada Santadgarn, Panus Hong, Suwijai Jatupornkongchai,
Ekkachak Chandon and Prinya Putthapiban

Preliminary analysis and solution for collapsed road embankment due to 47-56
drought in Pak Phanang, Nakhon Si Thammarat
Pisit Srivaranun, Thanwa Wibunsaran, Taweephong Suksawat
and Kawin Saiprasertkij

Reinforced embankment constructed along irrigation canal 57-62
Kritsada Teerachavalvong, Surasak Kaipinit, Taweephong Suksawat
and Kawin Saiprasertkij

The Furongian (late Cambrian) trilobite Thailandium’s endemicity reassessed along 63-82
with a new species of Prosaukia from Ko Tarutao, Thailand
Shelly J. Wernette, Nigel C. Hughes, Paul M. Myrow and Apsorn Sardsud

Regolith-landform mapping of the Gnaweeda Greenstone Belt, western Australia 83-95
Siriporn Soongpankhao

Any opinions expressed in the articles published in this journal are considered the author’s academic
autonomy and responsibility about which the editorial committee has no comment, and upon which
the editorial committee takes no responsibility

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รบั ผดิ ชอบ หรอื ไมจ่ ำ�เปน็ ตอ้ งเหน็ ด้วยกับขอ้ คดิ เห็นนัน้ ๆ แตอ่ ยา่ งใด

Copyright © 2020 by the Department of Mineral Resources of Thailand
visit Thai Geoscience Journal website at http://www.dmr.go.th
Designed and printed : Tonkid create Co., Ltd., tel. 0918821991, July 2020

Thai Geoscience Journal 1(1), 2020, p. 1-16 1
Copyright © 2020 by the Department of Mineral Resources of Thailand

ISSN 2730-2695 ; DOI : 10.14456/tgj.2020.1

A remarkable end-Permian boulder bed of conglomeratic limestone
at Nam Nao in NE Thailand: its biostratigraphical
and environmental significance

Shigeki Hada1*, Somboon Khosithanont2 and Hiroya Goto3
1Soemon-cho 1-8, Chuo-ku, Osaka 542-0084, Japan.

2Department of Mineral Resources of Thailand, RamaVI Rd.,
Ratchathewi, Bangkok, 10400, Thailand.

3Domoto 380-4, Tatsuno-cho, Tatsuno 679-4129, Hyogo, Japan.
*Corresponding author: [email protected]

Received 8 September 2019 ; Accepted 2 July 2020

Abstract

Litho- and bio-stratigraphic analyses on the Lower Permian Khao Pa Khi and Middle-Upper Permian
Khao Tham Yai limestones, and the siliciclastic Hua Na Kham Formation on clastic-dominant
continental shelves in the western margin of the Indochina Block record important aspects of the
extinction-related Guadalupian-Lopingian (G-LB) interval, and a large-scale sea-level drop of a global
environmental change in the low-latitudes of the East Paleo-Tethys. Fusulinid and foraminifer species
within the Khao Tham Yai Limestone record the abrupt disappearance of large-tested fusulines.
The Khao Tham Yai Limestone above the G-LB is characterized by the sudden flourishing of a diverse
range of smaller fusulinid and foraminifer species, together with the occurrence of a large number of
broken fragments of diverse large-tested fusulinids. The second disappearance of smaller foraminifers
occurred during the Wuchiapingian in the upper part of the Khao Tham Yai Limestone. These two
phases of disappearance of fusulinid and foraminifer species on the continental margin of the Indochina
Block likely appeared a little late compared to similar phases in the paleo-atolls of the mid-Panthalassa.
The Wuchiapingian Hua Na Kham Formation unconformably onlaps the Khao Tham Yai Limestone
replacing previous carbonate formation. These carbonate and siliciclastic formations are largely heteropic
facies and possibly interfinger with each other. A remarkable boulder bed of fusulinids and conglomeratic
limestones occurs on the top of the Hua Na Kham Formation. Fusulinid and foraminifer species in
boulders indicate that they were eroded off the Khao Tham Yai barrier reef and transported by submarine
debris flows that brought them to sites on the continental shelf where the Hua Na Kham Formation
deposited. Such catastrophic events may have been caused by large-scale eustatic sea-level drop.
The effects of this global environmental change on the continental margin of the Indochina Block may
have occurred a little later in the Wuchiapingian compared with subaerial exposure and erosion
reported from the G-LB interval in mid-oceanic seamounts that occur in mid-Panthalassa.

Key words: boulder bed of limestone, foraminifer species, Indochina Block, sea level drop,
Upper Permian

1. Introduction already published parts of a biostratigraphic
Since 2005, we have been carrying out investigation concentrating on the evolution and
geological and paleontological studies on a karstic extinction of a Middle and Upper Permian fusulinid
mountain in Khao Tham Yai (Hill of the Large and foraminifer fauna from a single limestone
Cave), about 30 km NW of Nam Nao in eastern unit named the Khao Tham Yai Limestone in the
Phetchabun Province, NE Thailand in collabora- Nam Nao district (Hada et al., 2015). We have
tion with the Department of Mineral Resources, clarified the following aspects of evolutionary
Thailand. From a regional tectonic perspective, and extinction patterns of fusulinid species in the
our research area is located along the western shallow-water Paleo-Tethyan shelf area in the
margin of the Indochina Block (Fig. 1). We have western margin of the Indochina Block.

2 Shikeki Hada et al. / Thai Geoscience Journal 1(1), 2020, p. 1-16

(5) Even smaller fusulinids abruptly become
extinct near the top of the Khao Tham Yai
Limestone during the Wuchiapingian.

(6) Eventually, clastic sediments unconformably
onlap (abut) the Khao Tham Yai Limestone
characterized by algae-foraminifera biota.

Figure 1: Index map showing the study locality and In this paper, we particularly provide details
the tectonic subdivisions of Thailand and adjacent regions of our recent study on the Upper Permian
(Hada et al., 2015). siliciclastic formation onlapping the Khao Tham
Yai Limestone and on a newly found boulder bed
(1) The Khao Tham Yai Limestone ranges from of fossiliferous and conglomeratic limestones on
the Wordian (middle Middle Permian) up to the top of the siliciclastic sequence focusing on
the Wuchiapingian (lower Upper Permian). a great variety of the fusulinid and foraminifer
The existence of the Wuchiapingian within a species identified from boulders, and their
single continuous limestone section rangingfrom characteristic occurrence. In relation to this new
Middle to Upper Permian is confirmed for the data, the aim of this paper is also to reanalyze the
first time in Thailand. biostratigraphic investigation of the smaller
fusulinid and foraminifer species above the G-LB
(2) Three fusulinid zones are differentiated with special reference to remarkable facies
in the Khao Tham Yai Limestone namely; change in the Khao Tham Yai Limestone.
Colania, Lepidolina and Codonofusiella zones
in ascending order. 2. Tectonic and geologic setting
Recently, Ridd et al. (2011) presented the
(3) Shell sizes of the fusulinid species in the widely available book entitled The Geology of
Lepidolina Zone display continuous rapid Thailand in the English language that attempts
morphological change along a one-way evolu- to cover the wide range of Thai Geology. In this
tionary path from small, primitive species with book Ueno and Charoentitirat (2011) provide an
simple structure to large, highly evolved species especially useful attempt to comprehensively
having a complicated wall structure. review the Carboniferous and Permian systems
of Thailand. They make great efforts to sort out
(4) The G-LB between the Guadalupian (Middle the informal naming of many stratigraphic units
Permian) and Lopingian (Upper Permian) within based on available paleontological data that
the Khao Tham Yai Limestone is clearly defined provide critical chronostratigraphic constraints.
as the boundary of the abrupt change in the Following their synthesis, we firstly attempt to
fusulinid assemblages from the elimination of readjust the stratigraphic and geotectonic data
large-tested Verbeekinids and Schwagerinids presented by Hada et al. (2015), then move to the
to the domination of small-shelled Schubertellids main issue.
with simple wall structure that underwent slower Since the epoch-making proposal by
evolutionary morphological change than earlier Bunopas (1981), Thailand has come to be
fusulinids and persisted and expanded in the understood as being fundamentally comprised
Wuchiapingian. of two distinct continental blocks; the Indochina
Block, which is regarded as a Cathaysian domain
to the east and the Shan-Thai Block, which is a
Gondwana-derived block associated with the
eastern Cimmerian Continent to the west (Fig. 1).
The Indochina Continental Block is
delineated to the west by the Nan Suture Zone
(Nan-Uttaradit Suture in Fig.1) (Figs.1 and 2).
The suture zone contains remnants of a now
closed back-arc basin that once existed in the

Shikeki Hada et al. / Thai Geoscience Journal 1(1), 2020, p. 1-16 3

western flank of the Indochina Block (Ueno and Figure 2: Major facies subdivisions for Late Paleozoic
Hisada, 2001). Upper Triassic red beds with rocks on the western margin of the Indochina Block
red chert pebbles that yield Middle Triassic (Wielchowsky and Young, 1985; Ueno and Charoentitirat,
radiolarians disconformably overlies the 2011).
serpentinite mélange of the Nan Suture Zone
in the Nan Mine, N Thailand. This indicates areas on the margin of the Indochina Block
that the back-arc basin closed during Late and reported that the strata of the Nam Duk Basin
Triassic time (Hada et al., 1999). Red chert is an are dominated by Permian slope-to-basin
important constituent element of the back-arc sediments and pre-dominantly consist
basin (marginal sea) that opened in the Permian of turbidites. We suggest that the Loei Suture
and closed in the Triassic. is not a suture between two microcontinents
Another enigmatic aspect of the Indochina inside the Indo china Block, nor is Loei Fold Belt
Block is the origins of the Nam Duk Basin. This a collisional orogeny. Rather it possibly
basin along the western margin of the Indochina originated as an intraplate strike-slip deformation
Block separates the Pha Nok Khao Platform to belt, and the Nam Duk Basin is a basin related
the east from the Khao Khwang Platform to the to intraplate strike-slip deformation. The northern
west (Fig. 2). It has been variously interpreted as extension of the Loei Suture or the Nam Duk
the Indosinian collisional orogen, the Loei Fold Basin is largely concealed by Mesozoic sediments
Belt (Helmcke and Lindenberg, 1983; Helmcke, thus relations to the Nan Suture Zone remain
1994) or a suture, the Loei Suture (Chutakosit- unclear (Fig. 2).
kanon et al., 1999; Charusiri et al., 2002). Ueno and Charoentitirat (2011) formally
Charusiri et al., (2002) suggested that it represents introduced the term Loei Group for a succession
a suture zone based on the existence of older rocks of carbonate and siliciclastic Pennsylvanian-
ranging from Upper Silurian to Cretaceous Permian strata associated with the Pha Nok Khao
including radiolarian chert as well as basic Platform on the eastern side of the Nam
and ultrabasic igneous rocks, which represent Duk Basin. In the southern part of Loei, this group
scraped-off ocean-floor rocks. It extends is composed of the siliciclastic Huai Som
from Loei to the east of the Nam Duk Basin.
However, the Loei Suture is still the subject
of much debate.
The Nam Duk Formation in the Nam Duk
Basin is composed of siliciclastic dominant
strata and has also been the subject of many
studies in the context of the geotectonic evolution
of Thailand. It has long been believed that
the formation represents a typical pelagic
flysch-molasse succession corresponding to
pre-, syn- and post-orogenic stages of an
‘Indosinian’ collisional orogeny based
on the classic ‘geosynclinal model’ (Loei
Fold Belt) (Helmcke and Lindenberg, 1983;
Helmcke, 1994). However, it is hard to draw
any conclusions in the context of the formation’s
orogenic development in the view of the
incomplete understanding of the stratigraphy
and stratigraphic relations between the Nam Duk
Formation and surrounding formations (Ueno
and Charoentitirat, 2011). Evidence for the
existence of a molasse sequence is also
questionable. Ueno and Charoentitirat (2011)
interpreted the Nam Duk Basin as an intracra
tonic depression between two shallow platform

4 Shikeki Hada et al. / Thai Geoscience Journal 1(1), 2020, p. 1-16

(mostly Pennsylvanian), carbonate Pha Nok This limestone sequence which is exposed
Khao (mainly Lower-Middle Permian) and extensively in the Nam Nao district, which has
siliciclastic Hua Na Kham (younger Permian) been regionally included in the Lower to Middle
formations (Chonglakmani and Sattayarak, Permian Pha Nok Khao Formation of the Loei
1984). Group and is termed the Khao Tham Yai Lime-
The Khao Tham Yai Limestone (Hada et al., stone (Hada et al., 2015). We previously redefined
2015) is extensively exposed in the Nam Nao the range of the Pha Nok Khao Formation from
district in NE Thailand and is assigned to the the Lower to Upper Permian on the basis of
carbonate Pha Nok Khao Formation of the Loei biostratigraphic data (Hada et al., 2015). Strata
Group on the Pha Nok Khao Platform. Fontaine of the formation include carbonate materials that
and Salyapongse (2001) and Fontaine et al. accumulated in situ on the shallow-water,
(2002) first showed that the Khao Tham Yai low-latitude Paleo-Tethyan shelf area within the
Limestone ranges from Murgabian (middle western margin of the Indochina Block.
Middle Permian) to the top of Median (upper The Khao Tham Yai Limestone crops out as
Middle Permian). Later Hada et al. (2015) proved a very large, elongated, N-S trending limestone
the age of the Khao Tham Yai Limestone extends hill about 10 km long in the Nam Nao National
to the Upper Permian (Wuchiapingian). Park in NE Thailand. It is well exposed on steep
Fontaine and Salyapongse (2001) and slopes, cliffs and the crest of the limestone hill in
Fontaine et al. (2002) reported a siliciclastic the Nam Nao district, and forms a continuous,
succession in the valley on the eastern side near homoclinal section estimated to be ca. 1700 m
of the Khao Tham Yai Limestone. It appears to thick (Fig. 3). It strikes NNW-SSE to NW-SE
stratigraphically overlie the Khao Tham Yai and dips moderately to the east (Fig. 4).
Limestone.Although, it was previously assigned We subdivided the Khao Tham Yai Limestone
to the Nam Duk Formation, it bears similarity into the Lower, Middle and Upper members
to the siliciclastic Hua Na Kham Formation (Hada et al., 2015). Figure 5 shows a composite
of the Loei Group as noted by Ueno and stratigraphic column and fusuline distribution of
Charoentitirat (2011). the upper part of the Lower Member and the
Fontaine and Salyapongse (2001) also made Middle and Upper members of the Khao Tham
a reference to the Khao Pa Khi Limestone that Yai Limestone (Hada et al., 2015). Fontaine et al.
is in direct contact with the Hua Na Kham (2002) has divided the Khao Tham Yai Limestone
Formation. It is sparsely fossiliferous and was into 8 horizons from the western side (base)
once regarded as Triassic, whereas Fontaine to the eastern side (top) of the hill. Lower, Middle
et al. (2002) later tentatively considered a and Upper members of the Khao Tham Yai
Permian age. We recently found Lower Permian Limestone approximately correspond to their
fusulinid species in the massive Khao Pa Khi horizons 1 to 4, 5 to 7 and 8, respectively.
Limestone and it is confirmed as Lower Permian First, provide a summary of the limestone
(see below). focusing on the evolutionary and extinction
In the following, we describe the fusulinid patterns of the larger fusulinid species of the
and foraminifer species, and the relevant facies Lower and Middle members of the KhaoThamYai
change of the Khao Tham Yai and Khao Pa Khi Limestone based on the findings of Hada
limestones of the Pha Nok Khao Formation et al. (2015)
of the Loei Group, and the boulder bed of
fossiliferous and conglomeratic limestones 3.1 Lower Member
at the top of the siliciclastic Hua Na Kham The Lower Member is further subdivided into
Formation of the Loei Group, which are distributed Units 1 and 2 in ascending order that correspond
in the Pha Nok Khao Platform on the eastern to the horizons 1 and 2, and 3 and 4 of Fontaine et
side of the Nam Duk Basin on the western flank al. (2002). Unit 1 is difficult to study because of
of the Indochina Block. widespread and dense tropical vegetation. Horizon
1 is also not rich in fossils and contains scattered
3. Lithology and fossils below the G-LB corals that are not well preserved and commonly
within the Khao Tham Yai Limestone of the destroyed by recrystallization. The limestone of
Pha Nok Khao Formation, Loei Group Horizon 2 is packstone containing algae, smaller

Shikeki Hada et al. / Thai Geoscience Journal 1(1), 2020, p. 1-16 5

Figure 3: Field photograph of the Khao
Tham Yai Limestone. The Limestone
forms a continuous, near homoclinal
section striking NNW-SSE to NW-SE
and moderately dipping eastward.

Figure 4. Geologic map (A) and structural cross-section (B) across the Khao Tham Yai Limestone, Hua Na
Kham Formation and Khao Pa Khi Limestone in the Nam Nao district, NE Thailand.

foraminifers, abundant massive corals, bryozoans, evolutionary lineage (Ozawa, 1970). It occurs
and rarely brachiopod. Fusulinid fossils are widely across SEAsia embracing Laos, Viet Nam,
extremely rare (Fontaine et al., 2002). Thailand and Peninsula Malaysia. It is a typical
Unit 2 consists of mostly massive, dark gray fusulinid species of the Wordian (middle Middle
limestone, commonly packstone rich in diverse Permian) of the Colania Zone in the Tethyan
fossils such as large fusulinids like Colania Province (e.g. Ozawa, 1970; Ota, 1977; Ingavat
douvillei (Ozawa), smaller foraminifers, algae, et al., 1980).
and large bivalves (Alatconchidae), but corals
are rare (Fontaine et al., 2002; Hada et al., 2015). 3.2. Middle Member
Colania douvillei, which is prolific in some The Middle Member consists of massive to
beds constitutes a transitional group between poorly bedded, black limestone and thick-bedded
Cancellina and Lepidolina in phylogenic lineage; dark gray limestone, commonly packstone and
i.e., Misellina-Cancellina-Colania-Lepidolina grainstone. It locally contains nodular or layered

6 Shikeki Hada et al. / Thai Geoscience Journal 1(1), 2020, p. 1-16

chert. This member is further subdivided into originated on paleo-atolls surrounding paleo-
Units 1 and 2 in ascending order (Hada et al., seamounts in mid-Panthalassa such as the Cache
2015) that approximately correspond to the Creek Terrane of British Columbia, Canada
horizons 5 and 6, and 7 of Fontaine at al. (2002), (Ross, 1995) and the Akiyoshi Terrane of Japan
respectively. The limestone contains abundant, (Sano and Kanmera, 1991). Based on this
diverse fossils consisting of fusulinids including evidence, Hada et al. (1996) proposed the
abundant large fusulinid species, smaller mid-Permian Colania-Lepidolina Territory
foraminifers, calcareous algae, crinoids, brachi- of the Colania-Lepidolina lineage in the paleo-
opods, bivalves that include extraordinarily large equatorial area of East Paleo-Tethys and mid-
bivalves (Alatoconchidae), bryozoans and rare Panthalassa. It is worth noting that distribution
fragments of corals. of Colania and Lepidolina is limited to the East
Unit 1 of the Middle Member is particularly Paleo-Tethys and Pan-thalassa region. Hada
characterized by Lepidolina asiatica (Ishii) and et al. (1996) also proposed another territory the
L. columbiana (Dawson). L. asiatica occurs in mid-Permian Neoschwagerina-Yabeina Territory
SE Asia including eastern Peninsular Malaysia of the Neoschwagerina-Yabeina lineage on the
(Jengka Pass and Pahang) and western Cambodia southern side of the Colania-Lepidolina Territory
(Sisophon). It belongs to the primitive species at low-latitudes in the East Paleo-Tethys and
of the genus Lepidolina that may most likely be mid-Panthalassa in the Southern Hemisphere.
evolved directly from Colania douvillei (Ishii, The habitat of Neoschwagerina-Yabeina stock
1966). Although L. columbiana was originally characterizing the Sibumasu (Shan-Thai) Block
reported as the genus Yabeina from the Cache is apparently different from that of the Colania
Creek Terrane of British Columbia, Canada (Ross, - Lepidolina lineage (Ishii et al., 1985).
1995). Goto et al., (1986) have described it under Unit 2 of the Middle Member also includes
the genus Lepidolina on the basis of a statistical a layer with broken fragments of extra-ordinarily
study of specimens. Limestones of the Cache large Alatoconchidae bivalves. Isozaki and
Creek Terrane formed at low-latitude in mid-Pan- Aljinovic (2009) confirmed that Alatoconchidae
thalassa and were later tectonically accreted to are characterized by their co-occurrence with
North America (Ross, 1995). L. columbiana is typical Tethyan faunal assemblages that include
sometimes included in L. asiatica (ex. Rui, 1983), large-tested fusulinids. They also concluded that
our specimens in Unit 1 are here referred to as the distribution of Alatoconchidae was restricted
more evolved, larger forms of L. asiatica on the to low-latitude (tropical) domains both in Paleo-
basis of prolocular diameter as described by Goto Tethys and Panthalassa. Alatoconchidae started
et al. (1986). L. columbiana has been found in and evolved in the Early to Middle Permian and
eastern Thailand, western Cambodia and eastern became extinct in the late Middle Permian. The
Peninsular Malaysia in SE Asia. stratigraphic range, their intimate association
Unit 2 of the Middle Member is specifically with large-tested fusulinids and timing of
characterized by L. multiseptata shiraiwensis extinction of Alatoconchids are applicable to
(Ozawa) in the lower part, L. multiseptata the example of the Nam Nao district in the
multiseptata (Deprat) in the upper part, and western margin of the Indochina Block in East
Lepidolina kumaensis Kanmera in the top Paleo-Tethys.
(Fig. 5). These fusulinids of the genus Lepidolina To sum up, the Middle Member of the Khao
widely occur in the Middle Permian limestones Tham Yai Limestone records a remarkable
of SE Asia including eastern Thailand, western example of the phyletic evolution in the genus
Cambodia, Viet Nam, Laos and eastern Peninsular Lepidolina. Notably, the genus Lepidolina
Malaysia. These are the characteristic species of apparently displays continuous and rapid
limestones not only in the continental blocks like morphological change along many one-way
the Indochina and South China blocks, which evolutionary trends from small, primitive species
were distributed in low-latitudes of the eastern with simple structure to large, highly evolved
Paleo-Tethys in Middle Permian time (Domeier species having a complicated wall structure at
and Torsvik, 2014) (Fig. 6), but also those of stratigraphically higher horizon levels (e.g. Ozawa,
the circum-Pacific region. The latter are species 1975; Kanmera et al., 1976; Hada et al., 2015).
occurring in the accretionary complexes Lepidolina kumaensis is one of the most

Shikeki Hada et al. / Thai Geoscience Journal 1(1), 2020, p. 1-16 7

Figure 5: Composite stratigraphic column and fusuline distribution of the upper part of the Lower Member and Middle
and Upper members of the Khao Tham Yai Limestone (slightly modified from Hada et al., 2015).

8 Shikeki Hada et al. / Thai Geoscience Journal 1(1), 2020, p. 1-16

Figure 6: 250 Ma (Permo-Triassic) paleogeographic reconstruction showing simplified plate boundaries and
with some major features labeled (modified from Domeier and Torsvik, 2014): A, Annamia (Indochina); SC,
South China; Sibumasu constituted part of the eastern Cimmerian Continent.

advanced forms of Verbeekinidae and, recently, 4. Lithology and fossils above the G-LB
Kasuya et al. (2012) confirmed its termination by with in the Khao Tham Yai Limestone of the
the end of the Capitanian (late Middle Permian). Pha Nok Khao Formation, Loei Group
Our study of fusulinid faunas confirms that the First, we provide a summary and
Middle Member covers the Lepidolina Zone re-examination of the smaller fusulinid and
and can be assigned to the Capitanian (upper foraminifer species of the Upper Member of the
Maokoan) in South China (Sheng, 1963). Khao Tham Yai Limestone based on the findings
In conclusion, after marking the ultimate of Hada et al. (2015) focusing in particular on
phase of their phyletic evolution of Permian their occurrence in relation to lithological change.
fusulinid faunas in the top of Unit 2 of the Middle The boundary between the Middle and Upper
Member, the fusulinid assemblage characterized members is clearly located between black
by long-ranging, large-tested Verbeekinids and limestones in the Middle Member and an
Schwagerinids abruptly became totally extinct overlying light gray limestone in the Upper Member.
below the Guadalupian (Middle Permian)- It is also clearly defined as the boundary of the
Lopingian (Upper Permian) boundary (G-LB). abrupt change in the fusulinid assemblage from
Our study documents a remarkable horizon large-tested Verbeekinids and Schwagerinids to
where the abrupt disappearance of large-tested the small-shelled Schubertellids as mentioned
fusulinids together with large bivalves occurred above. The Upper Member is divided into Units
at the G-LB. The so-called end-Paleozoic mass 1 and 2 in ascending order, and the former
extinction is the largest in Phanerozoic and has approximately corresponds to the horizon 8 of
been considered to have occurred in two-phases Fontaine et al. (2002). Unit 2 is newly distin-
(Jin et al., 1994): first, extinction at the guished as a unit separated from the horizon 8 of
Guadalupian-Lopingian boundary (G-LB; ca. Fontaine et al. (2002) and it forms the uppermost
260 Ma) and second, at the Permo-Triassic unit of the Khao Tham Yai Limestone.
boundary (P-TB; ca. 252 Ma). The importance Unit 1 of the Upper Member is mainly com-
of the most remarkable mass extinctions at the posed of thick-bedded, light gray limestone,
G-LB rather than the P-TB is emphasized commonly grainstone that characteristically
repeatedly (e.g. Isozaki and Ota, 2001; Isozaki, contains small-shelled fusulinids and smaller
2007; Kofukuda et al., 2014). foraminifers, abundant green algae, and totally

Shikeki Hada et al. / Thai Geoscience Journal 1(1), 2020, p. 1-16 9

lacks in situ (autochthonous) large-tested fusulin- Tethyan domains in Kwangsi, Kueichou and
ids (see below). The abrupt domination of small- Szechuan in South China (Sheng, 1963) occur in
shelled fusulinids, smaller foraminifers and green Unit 1. Based upon these observations, Unit 1
algae is accompanied by a remarkable lithological most likely corresponds to the Codonofusiella
change from black carbonaceous limestone Zone of Sheng (1963) in South China. Thus, the
to light gray crystalline, dolomitic limestone. age of Unit 1 of the Upper Member is considered
The lower half of Unit 1 is characterized by to be Wuchiapingian. In our recent investigation
a sudden flourishing of diverse species of of Unit 1, we found additional small fusulinid
Codonofusiella and Dunbarula, such as Codono- species as Nanlingella cf. meridiionalis Rui
fusiella cf. gubleri (Tien), C. kuwangsiana and Sheng, and Reichelina cf. media Maclay.
Sheng, C. kueichowensis Sheng, C. paradoxica Those fusulinids appear in the upper part of the
Dunbar and Skinner, Dunbarula paleofusilinae- Codonofusiella Zone and flourished in the lower
formis Sheng, D. cf. pusilla Skinner, Colaniella and middle part of the Paleofusulina Zone.
minima Wang, Reichelina cf. media Maclay, So, it is possible that the age of the upper part of
R. sp., Sichotenella orientalis Toumanskaya, Unit 1 and Unit 2 of the Upper Member extends
Nanlingella cf. meridionalis Rui and Sheng, to the Changhsingian although no typical
N. sp., Kahlerina cf. ussurica Sosnina, K. sp., Changhsingian (uppermost Permian) Paleofusu
and abundant green algae. lina-Reichelina assemblage has been recognized
In contrast, the upper half of Unit 1 is from the Khao Tham Yai Limestone. Existence
particularly notable for the occurrence of a large of the Wuchiapingian within a single continuous
number of broken fragments of diverse large-tested limestone section ranging from Middle to Upper
fusulinids having abraded outer volutions with Permian is confirmed for the first time in Thailand
iron-oxide-stained zones and abundant green (Hada et al., 2015).
algae accompanied by smaller foraminifers The newly differentiated Unit 2 of the Upper
the same as those in the lower part of Unit 1. Member is the stratigraphically highest unit of
Fusulinid bioclasts contained in this lithofacies the Khao Tham Yai Limestone. It is mainly
are of the same genus, Lepidolina, but include composed of massive, crystalline light gray
species at different stages of phyletic evolution, limestone commonly grainstone in which large
such as Lepidolina asiatica, L. multiseptata, algae are locally abundant, and fusulinid faunas
L. multiseptata multiseptata or L. kumaensis. are totally absent. Small foraminifers are all
Their sizes are remarkably smaller than typical broken, fragmented species of Codonofusiella,
sizes of the species because of abrasion. Other Reichelina and Colaniella. The age of Unit 2
broken fusulinid fossils include Pseudofusulina seems most likely to be Wuchiapingian based
sp., Sumatrina sp., etc. It is noteworthy that the on its stratigraphic position. Unit 2 of the Upper
limestones appear to contain bioclasts exhibiting Member is possibly comparable to a “barren
different degree of diagenesis (S. Mizutani, interval” reported by Ota and Isozaki (2006)
personal communication). Moreover, fossils of and assigned to shallow marine limestone in
the Khao Tham Yai Limestone are more or less mid-Panthalassa below the G-LB. In more detail,
broken reflecting an energetic environment. The Kofukuda et al. (2014) documented that the
facies rich in elongated-type of Dunbarula have disappearance of major taxa at the end of the
also been considered reflecting an energetic Capitanian occur in two steps in the barren
environment. Broken fragments of large-tested interval in mid-Panthalassa; i.e., first the
fusulinids undeniably represent a reworked fauna disappearance of large-tested fusulines in the
based on the mode of occurrence of large-shelled upper Capitanian, and then a second episode
fusulinids together with the small-shelled fusulinids involving smaller foraminifers also in the upper
and green algae. Capitanian, although smaller foraminifers
Unit 1 of the Upper Member is replete with reappeared above the GL-B. On the other hand,
diverse species of Codonofusiella and Dunbarula. in the Nam Nao district, the abrupt disappearance
Specifically, Codonofusiella cf. kueichowensis, of large-tested fusulines and a sudden flourishing
C. paradoxica Dunbar and Skinner and Dunba- of smaller fusulinid and foraminifer species
rula paleofusulinaeformis that characterize the clearly occurred across the G-LB, and the second
Wuchiaping Limestone in low-latitudes of disappearance of smaller foraminifers was

10 Shikeki Hada et al. / Thai Geoscience Journal 1(1), 2020, p. 1-16

registered during the Wuchiapingian in Unit 1 5. The Hua Na Kham Formation of the Loei
of the Upper Member of the Khao Tham Yai Group with special reference to the boulder
Limestone. Kofukuda et al. (2014) also reported bed of conglomeratic limestone
the subaerial exposure and erosion of mid-oceanic In the valley on the eastern side of the Khao
seamounts that occurred in the topmost barren Tham Yai Limestone, Fontaine and Salyapongse,
interval across the G-LB in mid-Panthalassa. (2001) and Fontaine et al. (2002) reported a
While, in the Nam Nao district, Unit 1 and the siliciclastic succession consisting of shale,
topmost barren interval of the Khao Tham Yai cleaved siltstone, minor sandstone and rare thin
Limestone is disconformably overlain by the beds of argillaceous limestone approximately
siliciclastic Hua Na Kham Formation and the 1000 m thick, and stratigraphically overlying the
top bed of the Hua Na Kham Formation is Khao Tham Yai Limestone. Although the
characterized by remarkable boulder bed of succession is intensely weathered and exposed
fusulinid and conglomeratic limestones derived only in scattered small outcrops, it is attributed
from the Khao Tham Yai Limestone (see below). to the Upper Permian Hua Na Kham Formation
Namely, the two phases of the disappearance of of the Loei Group (Ueno and Charoentitirat,
major taxa and a large-scale sea-level drop started 2011). Little has been known about the fossil
above the G-LB and occurred a little later during content of the Hua Na Kham Formation, but
the Wuchiapingian on the continental margin of Fontaine et al. (2002) reported poorly preserved
the Indochina Block. Large-scale sea-level drop at fusulinaceans as Codonofusiella, Dunbarula,
theendofCapitanian has been globally recognized Reichelina and Lepidolina from loose blocks of
through analyses of continental shelf areas around argillaceous limestone. This assemblage is
Tethys. The sea-level drop detected around similar to some beds in the eastern part of the
Paleo-Tethys and mid-Panthalassa during the late Khao Tham Yai Limestone and they suggested
Middle to early Late Permian likely reflected a a Midian (upper Middle Permian) age.
global cooling, which caused a large-scale Hada et al. (2015) demonstrated that onlap
eustatic regression (e.g. Haq and Schutter, 2008). of the clastic formation onto the Khao Tham Yai
Although the possible cause of a global cooling Limestone occurred on a larger scale replacing
is still not definite, Isozaki (2009) recently previous carbonate formation characterized by
proposed that a change in the core’s geodynamo algae-foraminiferal biotas. In detail, the onlap of
might have played an important role in determining siliciclastic rocks onto Unit 1 of the Upper Member
the course of the Earth’s surface climate and of the Khao Tham Yai Limestone to the south of
biotic extinction/ evolution. the fault identified by a marker bed of Alatocon-

AB

Figure 7: Field photograph of the Hua Na Kham Formation and the Khao Pa Khi Limestone. A: A distance view.
Boulders dispersed at the foot of the Khao Pa Ki Limestone hill just like loose blocks are outcrops of the boulder bed at
the top of the Hua Na Kham Formation. B: Close-up view of the boulder bed of the Hua Na Kham Formation.

Shikeki Hada et al. / Thai Geoscience Journal 1(1), 2020, p. 1-16 11

AB

CD E

Figure 8: Field occurrence of boulders of fusulinids and conglomeratic limestone at the top of the Hua Na Kham
Formation. (A) Fusulinid limestone. (B) An enlarged view of the fusulinid boulder. (C) Bioclastic limestone (rudstone)
(D) Brecciated limestone. (E) Bioclastic limestone accompaning chert band.

chidae and onto its Unit 2 (barren interval) to the various lithologies have been dispersed at
north of the fault is regionally recognized (Fig. 4). the top of a rather steep slope under the Khao
The strike of siliciclastic Hua Na Kham Formation Pa Khi Limestone hill just like loose blocks on
is NW-SE and is the same as the Khao Tham Yai the slope. Siltstones surrounding boulders are so
Limestone, but steeply dipping towards the strongly weathered that it is remarkably difficult
west. As repeatedly emphasized by Ueno and to judge in the field whether boulders are loose
Charoentitirat (2011), siliciclastic formations and blocks or lie within a siltstone matrix of the Hua
carbonate formations having similar ages in some Na Kham Formation. Fossils yielded from boul-
areas are largely heteropic facies and possibly ders match those of the Upper Member of the
interfinger with each other. The relationship Khao Tham Yai Limestone, whereas totally
between the Khao Tham Yai Limestone and the different fossils characterize the Lower Permian
siliciclastic Hua Na Kham Formation of the Loei Khao Pa Khi Limestone in direct contact to the
Group in the Nam Nao district shows that both east with the Hua Na Kham Formation (see
formations are heteropic and the latter finally below). At the same time, it is regarded as most
overlies the Khao Tham Yai Limestone. unlikely that boulders were accumulated by
Recently, we discovered a remarkable boulder farmers working in cornfields in the valley con-
bed of fossiliferous and conglomeratic limestones sidering its topographic position, their number
at the top of the Hua Na Kham Formation. Large and size. In conclusion, the large boulders of
boulders of a large-tested fusulinid limestone and fossiliferous conglomeratic limestones that
a remarkable conglomeratic limestone having appear to be loose blocks are interpreted as

12 Shikeki Hada et al. / Thai Geoscience Journal 1(1), 2020, p. 1-16

constituent rocks of the uppermost strata of the Khao Tham Yai barrier reef developed on
HuaNaKhamFormation(Fig.7A and B).Boulders clastic-dominant continental shelves (Fig. 9).
are composed of a brecciated limestone with or The occurrence of conglomeratic limestone
without fusulinid fossils, large-tested fusulinid boulders in a siliciclastic matrix indicates that
limestone, and bio-clastic limestone (rudstone). the carbonate sedments were lithified before they
Those boulders are sometimes accompanied by were enveloped by the flow of terrigenous mud.
chert nodules and bands. All these conglomeratic This is a reason that the limestones appear
limestones are regarded as part of an intrafor to contain bioclasts showing different degree
mational conglomerate and breccia in origin. The of diagenesis mentioned above.
shape of boulders is subangular, tabular and Similar large boulders beds of limestone are
disc-shaped, and the sizes of major axes of most known within the uppermost Jurassic-lowermost
boulders are approximately 1-3 m (Fig. 8A, B, Cretaceous Torinosu Group on Shikoku Island of
C, D and E). Boulders of fusulinacean limestone southwest Japan. Thepresence of limestone
contain Lepidolina cf. multiseptata, Verbeekina boulders derived from the mounds has been
verbeeki, Sumatrina sp., Pseudofusulina sp., interpreted as indicating that cessation of
and conglomeratic limestone boulders yield carbonate deposition may have been associated
abundant broken or fragmented and abraded with catastrophic events (Kano, 1988). Terrigenous
fusulinid species such as Lepidolina multiseptata sediments flowed over the carbonate deposits,
mulutiseptata, L. asiatica, L. sp., Colania killing the colonial organisms and stopping
douvillei, Sumatrina sp., Pseudofusulina crassa, carbonate sedimentation possibly indicating
P. padangensis, P. sp., Neoschwagerina sp. and that the cessation of the carbonate deposition may
Verbeekina verbeeki, and fusulinacean species have been associated with a large-scale eustatic
such as Pseudofusulina sp., Sichotenella sp., sea-level drop. The Ordovician Cow Head Breccia
Codonofusiella sp., Dunbarula sp., Kahllerina in the Appalachian Orogen in Canada is also an
sp., and Reichelina sp. These fusulinid and example of mixed angular breccia and softly
fusulinacean species are surprisingly similar deformed tabular blocks of limestone showing
to those of the Khao Tham Yai Limestone. different degrees of diagenesis and typically
In conclusion, boulders of fossiliferous and developed off the edge of the carbonate bank
conglomeratic limestones are interpreted to have at the ancient continental margin (James and
eroded off from the Khao Tham Yai Limestone Stevens, 1986). Similar coarse carbonate Upper
and brought to the Hua Na Kham Formation Devonian debris was deposited along the base
based on the fusulinids and foraminiferal fauna of a steep-walled platform as talus breccias
they contain. Boulders may be transported (via rockfall) and debris-flow breccias in the
by large-scale submarine debris flow from a Napier Range of the Canning Basin of NW

Figure 9: Model illustrating possible
development of the Khao Tham Yai barrier
reef (transverse section) on the continental
shelf of the western margin of the Indochina
Block. Limestone boulders were transported
by submarine debris flow from the Khao
Tham Yai barrier reef to sites on the
continental shelf where the Hua Na Kham
Formation was deposited (modified after
Kano, 1988).

Shikeki Hada et al. / Thai Geoscience Journal 1(1), 2020, p. 1-16 13

A south direction. The limestone is pale gray
or whitish gray, massive, vertically dipping,
B approximately 250 m thick (Fig. 8A). Stylolites
commonly observed in the limestone occur as
Figure 10. Field photographs of a fault scarp between the single low amplitude suture planes. It is in direct
Khao Pa Khi Limestone and the Hua Na Kham Formation contact to the west with the siliciclastic Hua Na
(A) and Riedel shear in its fault breccia indicate a reverse Kham Formation. It is sparsely fossiliferous and
sense of slip (B). was once regarded as Triassic (Fontaine and
Salyapongse, 2001). Fontaine et al. (2002)
Australia. Changes in sedimentary style on the later suggested a Permian age for the Khao
slope, reflecting differing rates of carbonate Pa Khi Limestone based on foraminifers,
production on the platform, are linked to relative and corals (from loose blocks). Fontaine et al.
sea-level fluctuations (George et al., 1997). The (2002) commented that if the corals belong to the
broken limestone and limestone breccias have Khao Pa Khi Limestone, they show that an
been also reported from the reef-cappedAkiyoshi inconsistent Upper Permian or Triassic age
seamount in the accretionary complex of Japan. and also suggested the existence of fault between
In this case, large-scale collapse of the seamount the Khao Pa Khi Limestone and the siliciclastic
and limestone cap was caused as the result of the Hua Na Kham Formation. Recently, we found
encroachment of the seamount into a trench area fusulinid fossils in outcrops of the Khao Pa
(Sano and Kanmera, 1991). Khi Limestone. Those are Misellina cf. otai,
The age of the Hua Na Kham Formation Sakaguchi and Sugano, M. sp. and Para-schwa-
in the Loei Group can be defined as Wuchiapingian gerina cf. fosteri (Thompson and Miller). Misel-
and possibly extends to Changhsingian lina otai is the most primitive representative
considering its stratigraphic relation with of the genus (Sakagami and Sugano, 1966).
the Khao Tham Yai Limestone, fossils of In late Early Permian time Misellina spread
conglomeratic limestone boulders and throughout Paleo-Tethys, although the occur-
argillaceous limestone. rence of localities, yielding this genus, are
6. The age of the Khao Pa Khi Limestone of sporadic (Ishii et al., 1985). Misellina gave rise
the Pha Nok Khao Formation, Loei Group to the Misellina-Cancellina-Colania-Lepidolina
The Khao Pa Khi Limestone is a continuous and the Misellina-Maklaya–Neoschwagerina-Ya-
succession of narrow hills aligned in a north- beina evolutionary lineages (Ozawa, 1970). The
Khao Tham Yai Limestone that is supposed to
be developed in the same continental shelves as
the Khao Pa Khi Limestone on the western
margin of the Indochina Block is characterized
by the former evolutionary lineage.
Our study of the fusulinid fauna confirms the
Misellina Zone of the Lower Permian for the
Khao Pa Khi Limestone of the Pha Nok Khao
Formation. The fault between the Khao Pa Khi
Limestone and the Hua Na Kham Formation is
confirmed at the bottom of the Khao Pa Khi
Limestone. It is N-S trending and dips steeply
east to vertical. Discontinuous shear plane
and foliation plane Riedel shear indicate a
reverse sense of slip consistent with uplift of the
Khao Pa Khi Limestone against the Hua Na
Kham Formation (Fig. 10A and B).

7. Concluding remarks
Litho- and bio-stratigraphic analyses of the
Lower Permian Khao Pa Khi and Middle-Upper

14 Shikeki Hada et al. / Thai Geoscience Journal 1(1), 2020, p. 1-16

Permian Khao Tham Yai limestones, and the interval in mid-Panthalassa, a large-scale
heteropic siliciclastic Hua Na Kham Formation sea-level drop associated with global environ-
indicate they accumulated on a clastic-dominant mental change inside the continental margin
continental shelf at low-latitude on the western of the Indochina Block occurred a little later
margin of the Indochina Block. We have during the Wuchiapingian. (6) Our recent study
clarified the following matters. (1) The abrupt of the fusulinid fauna confirms the Misellina
disappearance of large-tested fusulines with Zone of the Lower Permian for the Khao Pa Khi
large bivalves clearly occurred at G-LB within the Limestone of the Pha Nok Khao Formation.
Khao Tham Yai Limestone, and they never returned.
(2) The Khao Tham Yai Limestone above the Acknowledgements
G-LB is characterized by sudden proliferation of This study was started as the Project of Kobe
a diverse range of species of smaller foraminifers Women’s University, which was financed
and the occurrence of a large number of broken by the Association of Private Universities of
fragments of diverse large-tested fusulinids and Japan and the Yukiyoshi Institute. The field
abundant green algae. Broken fragments of research in Thailand has been carried out
large-tested fusulinids undeniably represent a with the permission and great support of the
reworked fauna from (3) The first disappearance Geological Survey Division, Department of
of large-tested fusulines and the proliferation Mineral Resources of Thailand. We express
of smaller fusulinid and foraminifer species our most cordial appreciation to the members
clearly occurred across the G-LB, and the of the Geological Survey Division. Special
second disappearance of smaller foraminifers thanks go to Jonathan Aitchison who provided
was registered during the Wuchiapingian. These valuable suggestions on our original manuscript
two phases of dis-appearance of fusulinid and for critical reading of the manuscript,
and foraminifer species on the continental and Winai Yaowanoiyothin for drafting of
margin of the Indochina Block have likely figures and editing task. We thank members
occurred a little later comparing to the phases of the Tham Yai Nam Nao Ranger Station
on the paleo-atoll in mid-Panthalassa. (4) of the Nam Nao National Park for their
The Wuchia-pingian siliciclastic Hua Na Kham assistance and collaboration in the field. By
Formation unconformably onlaps the Khao the way, we deeply regret to announce that in
Tham Yai Limestone replacing previous the end of August 2019 we received the very
carbonate formation characterized by algae- sad news of the death of one of authors,
foraminiferal biotas. A remarkable boulder Dr. Somboon of the Department of Mineral
bed of fusulinids and conglomer atic limestones Resources of Thailand. We would like to offer
occurs at the top of the Hua Na Kham Formation. our most hearty condolences to his relatives
The fusulinacean assemblage yielded within and friends and dedicate this paper to him with
boulders undoubtedly compares to that of the all our hearts.
Middle and Upper members of the Khao Tham
Yai Limestone. Therefore, it is reasonable to References
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Thai Geoscience Journal 1(1), 2020, p. 17-26 17
Copyright © 2020 by the Department of Mineral Resources of Thailand

ISSN 2730-2695 ; DOI : 10.14456/tgj.2020.2

Possible sources of elevated arsenic in surface and ground water,
Amphoe Banrai, Changwat Uthai Thani, Thailand

Apsorn Sardsud1, Onuma Khamphleang1 and Jitisak Premmanee2*
1Division of Mineral Resources Analysis and Identification, Department of Mineral Resources.

2An ex-official of the Department of Mineral Resources.
* Corresponding author: [email protected]
Received 30 September 2019 ; Accepted 2 July 2020

Abstract

This study is cooperation between the Division of Mineral Resources Analysis and Identification,
Department of Mineral Resources and the Uthai Thani Provincial Public Health Office to help and
verify elevated arsenic level at Tambol Nongjok/Nongbomklouy, Amphoe Banrai, Changwat Uthai
Thani because the elevated arsenic level may pose health risk to local residents. Geochemical techniques
were employed by collecting water and stream/lake sediments, and analyzing for arsenic covering the
target and adjacent areas. A total of 371 water samples were compiled. Assay results of 281 surface
water samples range from <2–2,713 ppb, average 97 ppb; and of 90 groundwater samples range from
<2–505 ppb, average 47 ppb. Integrated spatial studies of these water assays with geography, water flow
pattern and arsenopyrite mineralization outline 2 tiers of risk areas. Tier 1 arsenic assays ≥300 ppb,
covers 2 areas in south of Ban Thapfaimai and at Wat Nongmaitai, Tambol Nongjok and Tier 2 arsenic
assay ≥100 ppb, encompasses 14 villages in Tambol Nongjok/Nongbomkluay Changwat Uthai Thani;
Tambol Wangkan Changwat Suphanburi and Tambol Sukduenha Changwat Chainat. A total of 88 stream/
lake sediments samples were compiled. Assay results range from <5–167 ppm, average 31 ppm. A group
of high assays (75-167 ppm) are close to the expired tin-tungsten mining licenses at Ban Nongyaingern,
Tambol Wangkan. Other high assays (≥50 ppm) are contained within the Tier 2 area. These findings
indicate that water sampling is a more practical approach than sediment sampling in order to outline
the arsenic risk areas and may identify the point sources. Four possible arsenic sources were identified:
(1) Khao Koktungkung, (2) west of Ban Putakien (3) Wat Nongmaitai and (4) west of Ban Nongmaikean
where it was later found altered granite with quartz veins and disseminated arsenic rich sulfide minerals
at an under-construction water reservoir.

Key words: Arsenic, Banrai, geochemical exploration, sources, risk area, water sampling

Introduction sediments in this area during 2012 and 2013.
This project was initiated by the Uthai Thani Nevertheless, most of the mentioned records
Provincial Public Health Office (UTPHO). The did not study throughout the area but rather
Office has actively followed up the elevated concentrated on the known problematic sites.
arsenic level in surface water as well as in local The data under the DMR Hazardous Element
residents since 2011. Even though, elevated Project systematically cover parts of the area in
arsenic level in water of the area was known for Suphanburi and Uthai Thani, but no sampling in
many years. The Division of Mineral Resources nearby Chainat provinces.
and Identification, Department of Mineral Therefore, the Division of Mineral Resources
Resources (DMR), Ministry of Natural Resources and Identification, DMR launched this project in
and Environment filed the first records in 2006. early 2019 to systematically document
Later, some records were available from a elevated arsenic levels and hopefully identify the
cooperative project between the DMR and the possible sources. Geochemical prospecting
Department of Disease Control, Ministry of techniques were employed by collecting water
Health in 2009. Also, the DMR Hazardous and stream/lake sediments, and analyzing arsenic
Element Project sampled surface water and covering the target and adjacent areas.

18 Apsorn Sardsud et al. / Thai Geoscience Journal 1(1), 2020, p. 17-26

Study Area A group of hills, K. Koktungkung, Puchi and
The initial study area consists of 5 villages Pongngam present in the south and consist
(Bani Tapfaimai, Maiphongan, Nongmaikean, of meta-sediments, limestone and granite of
Keanpetphailin and Nongmaitai) of Tamboli Silurian/Devonian, Ordovician and Triassic
Nongjok and 1 village (B. Lanka) of T. Nong- Periods respectively. Contacts of these meta-
bomkluay, Amphoei Banrai, Changwati Uthai sediments and limestone with granite host
Thani (Fig. 1). However, after compilation tin-tungsten deposits. A few mines operated
of previous data, the study area was expanded around 1987 in secondary elluvial and alluvial
to include the nearby villages of T. Nongjok / deposits at K. Koktungkung and at B. Tapfaimai.
Nongbomkluay /Tapluang, A. Banrai, C. Uthai Jariyawat (1996) reported that the mineralization
Thani, of T. Wangkan /Nongkratum,A. Danchang formed in 1-10 cm quartz veins oriented N45W
/Doembangnangbuat, C. Suphanburi, of and N60E within granitic rock.
T. Sukduenha /Kaboktia,A. Noenkham, C. Chainat. Interestingly, those southern hills formed
The final rectangle of entire study area covers natural geographic boundaries of 7 Tambols
about 16x20 km or 320 km2. (Nongjok, Nongbomkluay, Wangkan, Nong-
Figure 1 shows the topography of the area makhamong, Nongkrathum, Sukduenha and
which consists of broad and gentle slope with Kaboktia), 4 Amphoes (Banrai, Danchang,
higher ground formed as an axis at the middle, Dermbangnangbuat and Noenkham) and 3
like a turtle back. The axis orients almost north- Changwats (Uthai thani, Suphanburi and
south direction and divides water flow into east Chainat).
and west directions. To the east, water curves to
southeast direction and drain into the Thachin Previous Data and Additional Sampling
River, C. Chainat. The west part, water runs into Figure 2 shows sample points including
Krasiao stream, then to Krasiao reservoir, previous and additional samples. The previous
A. Danchang, C. Suphanburi. Khaoii Phuklang water and sediment samples (Fig. 2A) were
and Urkhwai exhibit karst topography in the north compiled from many sources, such as DMR’s
and mainly consist of Ordovician limestone. reports, UTPHO, the DMR’s Hazardous Elements

Figure 1: Location and topography of study area, Banrai, Uthai Thani

i - Ban, Tambol, Amphoe and Changwat are local administrative names and refer to village, sub-district, district
and province respectively. In this report, they are abbreviated to B., T., A. and C. respectively.
ii- Khao refer to mountain or hill and in this report is abbreviate to K.

Apsorn Sardsud et al. / Thai Geoscience Journal 1(1), 2020, p. 17-26 19

Project (Uthai Thani and Suphanburi provinces) the DMR Hazardous Element Project (Premma-
and others, detailed in Premmanee (2019a). nee, 2019b). Note that World Health Organization
The samples consist of 32 streamsediments, (WHO, 2020) has suggested an arsenic safe
139 surface water, 50 ground water, and total content limit in drinking water of 10 ppb, while
221 samples. the Pollution Control Department (PCD, 2020)
Figure 2b shows the additional samples of Thailand has tabulated the standard arsenic
collected in April 2019. The new sample set values (refer to maximum permissible limit or
aim to fill-up spaces, create more density and MPL) in water and agricultural soil at 10-50 ppb
verify some assays in the problematic areas. and 3.9 ppm respectively.
Additional samples consist of 56 stream/lake Beside the water and sediments, UTPHO
sediments, 142 surface water, 40 ground water, collected urine samples from local residents
and total 238 samples. Note that these samples periodically every other year, since 2011 (Table
were collected, prepared and analyzed according 2) (Ms. Sukanya Pataisophon, personnel
to protocols in the Standard Method for Exami- communication). The samples were in the 5
nation of Water and Waste Water no.3113 (2017) villages of T. Nongjok and 1 villages of T. Nong-
for water samples and the Hazardous Waste Test bomkluay (village J1, J3, J4, J6, J7 and B1 on
Methods no.SW-846 (2019) for solid samples. Fig. 1). Results showed that 288 (55%) samples
These assays were combined into a single out of 520 samples are above acceptable levelsiv
set, total 459 samples (Table 1).Arsenic contents
in surface water, ground water and sediments Arsenic Distribution
average at 97 ppbiii 47 ppb and 31 ppmiii Figure 3 shows arsenic distribution in surface
respectively. These averages lay about 20, 10 and water (3A), ground water (3B) and sediments
2 times higher than the averages in surface water (3C). Elevated arsenic in surface water, ground
(4 ppb) and stream sediments (12-15 ppm) under water and sediments scatter around the tin-tungsten

Figure 2: Samples location maps, (A) previous samples and (B) additional samples.

iii - ppb – part per billion or microgram per liter (μg/l) and iv - Based on the Department of Desease Control (2019),
ppm – part per million or milligram perliter (mg/l) the acceptable levels refer to 2 conditions. Urine
sample collected from seafood consuming restricted
of 48-72 hours is at <50 μg/l and from the unrestricted
seafood consuming is at < 100 μg/dl.

20 Apsorn Sardsud et al. / Thai Geoscience Journal 1(1), 2020, p. 17-26

Table 1. Statistics of arsenic assays in surface water, ground water and sediments.

Assay statistics Surface Ground Combined water Sediments
water water (ppb) (ppm)
(ppb) (ppb)

Number of 281 90 371 88
samples

Minimum <2 <2 <2 <5
2713 447 2713 167
Minimum 97.0 46.8 85.9 31.1
167.2 83.1 153.8 30.7
Average*

Standard
deviation*

Detection limit 2 2 2 5
(DL) 3
35
Number of <DL 8 27
6 (2713,1589,
Outlier 6 (2713,1589, 1 (505) 1350, 1295, 1206,
1350, 1295, 1206,
1170)
1170)

Note: * If the assay is <DL, then DL/2 will use for calculation

Table 2. Urine arsenic levels in local residents.

Testing year T. Nongjok T. Nongbomkluay Combined
202
2011 Total samples 202 -
Anomaly (%) 73 (36%) - 73 (36%)
86
2013 Total samples 86 -
Anomaly (%) 49 (57%) - 49 (57%)
101
2015 Total samples 101 -
Anomaly (%) 86 (85%) - 86 (85%)
171
2017 Total samples 96 75
Anomaly (%) 38 (40%) 42 (56%) 80 (47%)

Total 520 samples with 288 (55%) anomalous values

Apsorn Sardsud et al. / Thai Geoscience Journal 1(1), 2020, p. 17-26 21

Figure 3: Arsenic distribution in (A) surface water, (B) groundwater and (C) stream/lake sediments.

22 Apsorn Sardsud et al. / Thai Geoscience Journal 1(1), 2020, p. 17-26

prospective areas of K. Koktungkung and Risk Areas and Possible Point Sources
more densely to the north, especially at Many spatial factors (such as topography,
abandoned tin mining pits, south of B. drainage system, arsenic mineralization
Tapfaimai. The furthest north high arsenic style, geological environment and others) will
assays distribute along water channels north help to outline the risk areas and to identify
of B. Maiphongam and Putakien. arsenic point sources. As mentioned, water
The highest arsenic assay (2,713 ppb) in assays will limit the risk areas compared to
surface water was collected from a small sediment assays. And yet, many authorities
water channel, south of B. Tapfaimai. 4 more recommend MPL in consumable water at 10-50
high assays (>1,000 ppb) were detected at the ppb. So, the practical threshold arsenic assays
tin mining pits in this area. The 6th high in surface water should be higher than the MPL
assay (1,170 ppb) is located at Wat Nongmaitai, in order to separate the risk areas. In this study,
B. Nongmaitai, about 3.5 km east of the arsenic in surface water average at 97 ppb while
Tapfaimai’s tin pits. Interestingly, a group of 47 ppb in ground water. Therefore, surface
high arsenic values (100-499 ppb) in surface water assay at 100 ppb is selected for the
water depicted at B. Maiphongam and further practical threshold value.
north which is located in different drainage The 100 ppb lines were manually drawn
catchment to the one of B. Tapfaimai. These following drainage system and catchment areas,
show that arsenic sources may not only so as the 300 ppb lines (very high arsenic
originated from the tin mining/prospective values). Figure 5 shows results of the 2 tiers of
areas of K. Koktungkung but from unidentified risk areas as follow.
natural sources northeast of B. Maiphongam Tier 1: arsenic assays ≥ 300 ppb in surface
as well. water, encompass 2 areas: (1) south of
High arsenic assays in ground water display B. Tapfaimai where there are many abandoned
similar patterns to surface water, but at tin mining pits and (2) Wat Nongmaitai,
B. Phutakien (Figs. 3A and 3B) where mixed of B. Nongmaitai; both at T.Nongjok A. Banrai
very low and high arsenic assays (≤50 to ≥100 C. Uthai Thani, covering approximately 4 square
ppb) detected in ground water. The highest assay km or 2,500 rai.
(505 ppb) was found in 30 m water well here, Tier 2: arsenic assays ≥ 100 ppb in surface
but all surface water yield <50 ppb. In addition, water, encompass 14 villages of B. Putakien,
the downstream assays of surface water gradually Maiphongam, Koksaard, Nongmaikean,
increase for about 5 km, i.e. 10, 22, 59, 72, 135 Tapfaimai, Keanpetpilin, Nongmaitai,
and 128 ppb, from the village. These findings T. Nongjok; B. Lanka, T. Nongbomklouy,
are illustrated (Fig. 4) showing possible A. Banrai, C. Uthai Thani; B. Nongyaingern,
transport mechanism of arsenic in water of Bungyang, Wangthong, Wangkan, Phunglouang,
this area. It is estimated that arsenic may be T. Wangkan, A. Danchang, C. Suphanburi; and
mobilized as far as 10 km from the sources B. Huaisong, T. Sukduenha, A. Noen Kham,
High arsenic (≥75 ppm) in sediments C. Chainat; covering approximately 65 square
distributed in 2 areas, east/northeast of km or 40,000 rai..
K. Koktungkung and around B. Maiphongam Note that the 100 ppb line is open at
and Phutakien. Medium high assays (25-74 T. Wankan due to the fact that not enough
ppm) located in those tin pits at B. Tapfaimai. samples in the area.
These results do not quite agree with water Point sources of arsenic are picked from
assays. It seems that arsenic in sediments distribution pattern of arsenic in water and
disperse irregularly around the sources. sediment, topography, arsenic mineralization
However, due to sampling period during the style as well as geological environment.
dry season, very limited stream sediments were
collected, but the majority were lake/pond Although, initial fieldwork at the tin-tungsten
sediment which may not represent transported prospective area of K. Koktungkung found no
materials. So, sediments sampling may not the evidence of primary sulfide minerals such as
practical in this case. pyrite or arsenopyrite, only some iron oxides are
found on the surface. Still, K. Koktungkung

Apsorn Sardsud et al. / Thai Geoscience Journal 1(1), 2020, p. 17-26 23

remains the most likely important point source Luckily, later field work at an under-construction
of arsenic. Arsenic in this area radially distribute water reservoir of B. Nongmaikean in July 2019,
into water channels of 10 villages: Tapfaimai, has found outcrops of altered granite with thin
Lanka, Huaisong, Bungyang, Wangthong, Wang- (<5cm) quartz veins and arsenic rich sulfide
kan, Phungluang, Nongyaingern, Nongmaitai and minerals (Fig. 6). Rock chip samples of mixed
Keanpetpailin.Arsenic from this source is limited altered granite with weathered sulfides minerals
to the south-east side of the water channel running and altered granite gave 4,890 and 25 ppm
from B.Nongmaitai to Nongmaikean. arsenic respectively. This evidence confirms an
On the other north-west side of the water arsenic source. However and inexplicably,
channel, west of B. Nongmaitai, Keanpetpailin, 2 water assays at this reservoir gave 20 and
Nongmaikean, arsenic remains high in water 23 ppb arsenic which are in the normal range.
indicating other sources beside from the K. Kok-
tungkung. High arsenic assays were obtained Conclusions and Remarks
around B. Putakien and Maiphongam which 1. Geochemical prospecting techniques
located in different catchment basin to the are an effective tool to outline the risk areas
K. Koktungkung, so, the areas may hold some and to identify the sources. It also demonstrates
concealed arsenic sources. Very high arsenic in that elevated arsenic sources not only from known
water (Tier 1 area) is present at Wat Nongmaitai; tin-tungsten mining areas but also from other
so an arsenic source should be in this area as well. concealed sources. In this case, water samples
In summary, there are 4 possible point sources: are more practical than sediment samples, but
(1) K. Koktungkung, (2) west of B. Putakien both should be concurrently conducted for
and Maiphongam, (3) Wat Nongmaitai, B. Nong- confirmation. It is estimated that arsenic may be
maitai, and (4) west of B. Nongmaikean (Fig. 5). mobilized for 10 km from a source.

Figure 4: Possible transport mechanism of arsenic at Ban Phutakien, Banrai, Uthai Thani.

24 Apsorn Sardsud et al. / Thai Geoscience Journal 1(1), 2020, p. 17-26

Figure 5: Arsenic risk areas, Banrai/Danchang/Noenkham, Uthai Thani/Suphanburi /Chainat.

Apsorn Sardsud et al. / Thai Geoscience Journal 1(1), 2020, p. 17-26 25

Figure 6: Nongmaikean water reservoir showing quartz veins in altered granite with disseminated arsenic rich sulfide
minerals.

2. The 100 ppb threshold value in surface 4.Any related government authorities should
water assay, a simple and rational figure, has continue their rolls in the area, such as UTPHO,
separated the risk area in this study, but may not DMR, Local Administrative Offices, etc.
be effective in the others. However, the figure 5. A few research type questions remain
may be used for a quick evaluation basis beside un-answered, such as low arsenic content in
the MPL values (10-50 ppb for drinking and water at the reservoir where some rich arsenic
consumable water). sulfide minerals was identified, distribution
3. Local residents in the risk and nearby pattern or behavior of arsenic in surface and
areas should be mad aware of this elevated ground water at B. Phutakien, or dispersion
arsenic in surface water. Large water supply distance of arsenic from source into water system
system should consider bringing from outside and surrounded area.
the risk area with acceptable arsenic level.
Rain water is the best alternative for drinking water.

26 Apsorn Sardsud et al. / Thai Geoscience Journal 1(1), 2020, p. 17-26

Acknowledgement Pollution Control Department of Thailand. (2020).
The authors gratefully thank the Department Standard for Arsenic in Drinking Water.
of Mineral Resources who provide funding http://www.pcd.go.th/info_serv/reg_std_
and gave us opportunity to study this project. water01.html#s3 (in Thai)
We would like to thank the Uthai Thani Pollution Control Department of Thailand. (2020).
Public Health Office personnel, especially to Standard for Arsenic in Surface Water.
Ms. Sukanya Pataisophon who provide all http://www.pcd.go.th/info_serv/reg_std_water
information related to this study as well as 05.html#s3 (in Thai)
helping us in the field, to all health care personnel Pollution Control Department of Thailand. (2020).
at Ban Maiphongam Health Promoting Hospital, Standard for Arsenic in Ground Water.
T. Nongjok, A. Banrai, C. Uthai Thani who help http://www.pcd.go.th/info_serv/reg_std_water
collecting samples. Also, we like to express 03.html (in Thai)
our sincere to T. Nongjok, Khun Sangop, Pollution Control Department of Thailand. (2020).
who assist us in the field. Standard for Arsenic in Agricultural Soil.http://
Last, we would like to give special thanks www.pcd.go.th/info_serv/reg_std_soil01.html
to the officials in the Division of Mineral (in Thai)
Resources Analysis and Identification, DMR Premmanee, J. (2019a). Study on Possible Sources
who help to collect all samples, preparation of Arsenic Distribution in Uthai Thani province,
and analysis. They also help to review and Department of Mineral Resources, Bangkok,
compile the data for this project. Thank to 79p. (in Thai)
K. Thawatchai Cheulaowanich, K. Nikhon Premmanee, J. (2019b). Arsenic and Cadmium:
Chaiwongsen who gave us valuable comments Under the DMR Hazardous Elements Project,
and discussion. in Geothai 2562, at The Berkley Hotel Pratunam,
Bangkok, 16-17 September 2019, p. 3-5.
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Thai Geoscience Journal 1(1), 2020, p. 27-46 27
Copyright © 2020 by the Department of Mineral Resources of Thailand

ISSN 2730-2695 ; DOI : 10.14456/tgj.2020.3

Transition between the Thabsila metamorphic complex and the Lower Paleozoic
formations and their sandstone provenance,
Kanchanaburi, western Thailand

Sirot Salyapongse, Praipada Santadgarn, Panus Hong, Suwijai Jatupornkongchai,
Ekkachak Chandon and Prinya Putthapiban*

Geoscience Program, School of Interdisciplinary Studies, Mahidol University,
Kanchanaburi Campus, 199 Moo 9, Sai Yok, Kanchanaburi, Thailand, 71150.

*Corresponding author: [email protected]
Received 28 November 2019 ; Accepted 2 July 2020

Abstract

In Kanchanaburi province of western Thailand, the oldest three rock units include the Thabsila regional
metamorphic complex exposed side by side with the Cambrian Chao Nen and the Ordovician Tha Manao
formations, possessing field relation, petrography and geochemistry strongly suggesting a transitional
relationship. The latter two rock formations are equivalent to the Cambrian Tarutao Group and
the Ordovician Thung Song Group from southern Thailand. They are characterized by alternating
lithofacies of argillites, siliciclastics and carbonates. The gradational nature among them both
in lithology and grade of metamorphism with only a single mode of foliation development indicates
one episode of progressive regional metamorphism. Modal compositions of the Upper Thabsila and the
Chao Nen meta-siliciclastic sandstones show them as original quartz arenite and subarkose to arkosic
sandstones. Their provenances was from a continental block setting. The chemical discrimination
diagrams indicate they have been deposited in a passive continental margin environment and have an
asymmetrically cyclic sedimentation habit. This evidence implies that there is no unconformity between
the Thabsila complex and the Lower Paleozoic formations. Although this terrain was subjected
to a series of northwest dextral strike-slip fault movement, their gradational nature in grades of
metamorphism is, in part of some sections, still preserved. Their sharing of the same provenance and
the tectonic setting show that they were continuously deposited throughout the long history of the
Shan-Thai terrane (up to as young as around Carboniferous, the timing of tectonically uplifting by the
incoming of volcanism to this terrane). The underlying older Precambrian basement, the source rock
of the Thabsila complex have never been observed. Probably have been re-melted to the common
foliated Triassic S-type granite in western Thailand.

Key words: Cambrian, Ordovician, regional metamorphism, sandstone provenance

I. Introduction This paper characterizes the apparent
The lithologic transition between the similarity between the quartz mica schist, quartz
Thabsila complex and the lower Paleozoic rocks schist and the foliated feldspathic quartzite of the
exposed in Kanchanaburi and northern Thailand Upper Thabsila complex and the Cambrian Chao
areas have been questioned for many decades Nen feldspathic (-micaceous) quartzites,
since the German Geological Mission to Thailand and shows a commonality in sedimentary,
(1972) and Bunopas, (1981). The study area is petrographic mode, provenance and geochemistry
along the road to Sri Sawat district, passing along that constrains their transition.
the Khwae Yai river between Ban Tha Manao and
Ban Mong Krathae, Kanchanaburi (Fig. 1). II. Geological setting
Nevertheless, most of the mentioned records In relation to the field relationship between
did not study throughout the area but rather the high grade Thabsila complex and the nearby
concentrated on the known problematic sites. Lower Paleozoic (Chao Nen and Tha Manao)
The data under the DMR Hazardous Element formations, the conclusion has been drawn
Project systematically cover parts of the area earlier since the time of the German Geological
in Suphanburi and Uthai Thani, but no sampling Mission (1972), and subsequently Bunopas
in nearby Chainat provinces. (1981) who confirmed the German Mission’s

28 Sirot Salyapongse et al. / Thai Geoscience Journal 1(1), 2020, p. 27-46

Figure 1: Index map showing the studied area of the Thabsila complex (1) and the
Chao Nen-Tha Manao formations (2) adjacent to the Khwae Yai River, in Kanchanaburi.

conclusion that in most of the places, there is an control on the occurrence of the foliated contact
obscured and questionable unconformity with metamorphic rocks being generated (Salyapongse
subsequent slip movement. Bunopas (1981) et al., 2015). Generally, once the originally
noted that, there is a drastic change in metamorphic regional lower grade country rocks have been
grade in many places between the higher grade upgraded to a higher grade and mimically imitated
Inferred Precambrian and the lower grade Lower the original foliation and increasing grades up to
Paleozoic rocks in Thailand. This contact relation even calc-silicate rocks and sillimanite mica schist
is generally a fault contact. originated from a commonly low-grade Cambrian
In Kanchanaburi (table 2), the metamorphic to Siluro-Devonian rocks.
nature of the lower Paleozoic rocks is quite Nanthasin et. al, (2012) summarized the
clearly developed and distinctive cleavage is Thabsila metamorphic complex into four units
obvious. For the regional metamorphic rocks that based on lithology from younger to older units:
have been subjected to only one episode of (1) UnitAis composed of marble, mica schist and
metamorphism and range in grades from higher quartzite, (2) unit B comprises mylonites, (3) unit
Amphibolite facies progressively lowering to slate C is composed of calcsilicate, and (4) unit D
or cleaved rock of the lower Greenschist facies comprises various gneisses. Their approximation
and faded away around the Upper Paleozoic rocks. has been based on geothermobarometric and
The other kind of metamorphic rocks belonging pseudo section of the 4 Thabsila unit as indicating
to the occurrence from contact metamorphism by PT ranging from Lower T / intermediate P at
large body of foliated Triassic S-type, volatile rich 500-650 °C / 5-6.5 Kb up to 640-719 °C / 5.5-8 Kb,
granite which is common and widespread in probably of Barrovian Facies Series conformably
isolated intrusions ranging from batholith to from top to bottom as a progressive sequence.
small satellitic and isolated bodies (pluton) but The ages of metamorphic events in western
conjoined at depth forming a large batholith. Thailand is controversial. Nanthasin et. al, (2012)
This kind of foliated contact metamorphism gave a metamorphic age of Eocene which
is affected only to the lower grade part of the contradicts the earlier interpretation on meta
regional metamorphism. By the time of intrusion, morphism age which quoted as Late Triassic
the relative thermal control between the intruding (Hansen et al, 2014), and thought to represent a
and the intruded rocks must be the important Barrovian Facies Series. Generally, the dislocated

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metamorphism is restricted to a narrow fault III. The Upper Thabsila meta-siliciclastic
zone which obviously from Nanthasin et. al’s sandstones
description of mylonite unit that seems to be This unit, which is about 2400 m thick
restricted only in the zone B. On the other hand, belonging to the upper part of the Thabsila is
it is doubtful that the cataclastic metamorphism exposed just across the Khwae Yai River fault
is high grade enough for the recrystallization of the valley to the west around Ban Pong Pat near Tha
zircon and produced the Thabsila metamorphic Thung Na dam (Table 3 and Fig. 2). Generally,
complex which cover an area more than one the transferring of the Upper Thabsila sequence
thousand square kilometer. The commonly to the Lower Paleozoic rocks frequently has been
tourmaline rich accessory mineral in various obscured by faulting and specifically around the
kind of rock for example quartzite and quartz Tha Thung Na area (Fig. 2). Observation along
schist in Thabsila area is very common as the the Khwae Yai fault zone by traversing their
same as that commonly found in metamorphic geologic cross-section for many kilometers
pegmatite. A very interesting publication by Hay down south revealed an obviously through a
and Dempster (2009), presented a special kind of unique key bed containing a characteristic
low temperature metamorphism which induced metamorphic mineral allowing their equilibration
a zircon rimming indicating quite young event. very nicely along both side geology, and
Since the Zr age was derived at 55 my which is can be concluded as an early remark that, the
quite young and seems to relate to the Eocene Khwae Yai fault zone was a kind of horizontal
collision between Asia and Eurasia since the last strike-slip fault and having dextral offset around
55 Ma. However, a detailed survey by Musikarak 15 km. Even though the lack of unconformity
(2019) reported the event of Eurasia–India collision evidence, Bunopas (1981) has assigned the
is related to a dextral movement and only caused age of the Thabsila as inferred Precambrain
brittle deformation contrasting with the common basing on their apparent difference in grades
ductile feature in this area which is sinistral and of metamorphism as had been impressed at
originated earlier. that time.

30 Sirot Salyapongse et al. / Thai Geoscience Journal 1(1), 2020, p. 27-46

Sirot Salyapongse et al. / Thai Geoscience Journal 1(1), 2020, p. 27-46 31

Table 3. Stratigraphic column of Thabsila metamorphic complex (reconstructed) and Chao Nen-
Tha Manao formations in Kanchanaburi.

32 Sirot Salyapongse et al. / Thai Geoscience Journal 1(1), 2020, p. 27-46
Table3.1 Symbols of Stratigraphic column of Thabsila metamorphic
complex and Chao Nen-Tha Manao formations in Kanchanaburi.

Figure 2: Geologic map of the Thabsila sequence.
Figure 2.1: Explanation of Thabsila metamorphic complex.

Sirot Salyapongse et al. / Thai Geoscience Journal 1(1), 2020, p. 27-46 33

The geologic map of the Thabsila meta
morphic complex (Fig. 2) has been subdivided
into the Lower and the Upper parts and in zones
from A to E, as a revised version from Muang-
phongoen and others (2015). Both the Lower and
the Upper Thabsila units, have been subdivided
into zones lithologically and structurally more
or less coincident with the many insignificant
fault lines (Fig. 2). The contrast in grades of
metamorphism is noticeable also in the meta-
siliciclastic sandstones, which alternate with
other meta-pelitic rocks only in the Upper Thab-
sila unit. However, the Upper unit exhibits a
transition from a lower grade, finer-grained
biotite paragneiss (Fig. 3) grading to a
coarser-grained banded or augen biotite-horn-
blende/quartzo feldspathic paragneiss with
calc-silicate and migmatite in the lower part.

Figure 4: Horizontal slip fiber (slickenside fibers)
in the meta-limestone cliff which developed on the
bedding plane of Permian limestone exposed along
a road-cut outcrop next to the nearby dextral movement
strike-slip fault.

Figure 3: ASy 232731. Fine-grained paragneiss started (Salyapongse, et. al., 2019), as well as an
segregation into many thin leucocratic threads, eastward decreasing in grades of metamorphism,
an indication of a lower grade paragneiss, which has been have been described also from the intercalated
increased to a higher grade, rendering more thicker pelitic horizons by Muangphongoen et al.,
bandings and developing feldspathic augen when moving (2015). Within the Upper Thabsila unit, however,
to the west. Ductile shearing is considered localized and there are many horizons of quartz-mica
not show consistent or extensive distribution. schist, quartz schist, and foliated quartzite which
are here referred to as meta-siliciclastic
Generally, all the northwestern strike-slip sandstones alternating with other meta-pelitic
faults were horizontally dislocated parallel rocks only in the Upper Thabsila complex.
to the metamorphic layering, so that their Correspondingly, both of the meta-siliciclastic
consecutively transitioning nature are still horizons and the meta-pelitic horizons are
preserved and can be recognizable along strike exhibiting conformably and progressively
across their transitional zone (Fig. 4). This has decreasing in grades eastward in the same fashion
been observed to establish throughout the and prograding further to the younging direction
stratigraphic column westwardly, although towards the Lower Paleozoic as well. Another
many fault lines have been detected (Fig. 2). important lithological type was found as
The sequential evolution of the mineral alternating calc-silicate, marble and meta-
assemblages in the Upper Thabsila complex limestone at least two lensoid bodies have been
detected.

34 Sirot Salyapongse et al. / Thai Geoscience Journal 1(1), 2020, p. 27-46

III-1. Petrographic analysis of the Upper (sample no.1 in Table 4). Further in the younging
Thabsila meta-siliciclastic sandstones horizons, particularly in the meta-siliciclastic
The Upper Thabsila sequence from high sandstone, they are characterized by dominant
to low grade starts the alternating sequence with muscovite over the biotite and the mineral grain
lower grade biotite paragneiss (Fig. 3), quartz- sizes are sharply reduced. (Figs. 5-7). This
fibrolite-garnet mica schist, quartz schist, textural feature shows a decrease in grain size
andalusite phyllitic schist, banded quartzite, along with a reduction in grade of metamorphism.
andalusite quartzite, andalusite-kyanite phyllitic Considering the whole Upper Thabsila complex,
schist/phyllite, foliated quartzite and slate (See the original sedimentary protoliths show an
more detail in Fig. 2). These packages of rocks increasing maturity toward the younger beds
have strike-slip fault contact with the Lower (sample no.5 and 6 see Fig. 2 and Fig. 18).
Paleozoic rocks. In the lowest part overlying To facilitate feldspar identification for point
the fine-grained biotite paragneiss, a mica schist counting, it can be accomplished by etching the
unit illustrates a foliated texture defined by uncovered thin section with conc. HF for about
mica and quartz with hardly recognized minor 20 seconds (Figs. 12 and 13). By this method,
feldspar, localized red garnet, biotite, fibrolite and the feldspar relief becomes more distinctive
muscovite with accessories apatite and zircon than quartz and turned extinct in XPL.

Figure 5: ASy 236730 (no. 1, Zone B) XPL Quartzofeld- Figure 6: ASy 243730 (no.4, Zone C) XPL. Foliated
spathic garnet mica schist showing foliated texture defined quartzite in of lower grade, having foliated texture defined
by biotite and a lesser amount of muscovite including with by elongated quartz aggregates with minor muscovite and
garnet and apatite. The availability of the feldspar is hardly opaque minerals. Tourmaline is quite common in the Upper
identifiable if it lacks twinning. Comparatively the mica Thabsila.Accessory zircon is usually detected. (Abbrev:ASy
grains are distinctively larger grain sizes than the lower grade = Amphoe Sai Yok 1:50,000 map sheet)
units to the east. (Abbrev: ASy = Amphoe Sai Yok 1:50,000
map sheet)

Figure 7: ASy 257720 (no. 6, Zone D) XPL. Foliated
quartzite further eastward, exhibiting foliated texture defined
by a very fine-grained flake of muscovite and an elongated
quartz aggregate showing sutured grains caused by
metamorphism and deformation with accessory zircon.
(Abbrev: ASy = Amphoe Sai Yok 1:50,000 map sheet)

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IV. The Chao Nen and the Tha Manao meta- occurr in a dislocated fault-slab within the fault
siliciclastic sandstones zone along the Khwae Yai river valley (Fig. 8).
The Cambrian Chao Nen and the Ordovician The Chao Nen and the Tha Manao formations
Tha Manao rock sequences were formed (Fig. 8) exposing further north along the road,
as elongated bodies sub-parallel to the north- were proposed by Bunopas (1981) to be
west-trending Si Sawat dextral strike-slip fault originally deposited as a continuous sequence
zone more or less running along the Khae Yai from siliciclastic rich graded to calcareous
river valley. Upper Paleozoic and the Mesozoic sandstone, sandy limestone, limestone and
continental red beds can be respectively observed argillaceous limestone characterizing upward
to the west and far west. Whereas the marine facies change of the two rock units. The total
Permian clastic rock units with the fusulinid thicknesses of these rock sequences are
Monodiexodina sp. in a small limestone lens, approximately 3,500 m.

Geologic map of the Chao Nen quartzite

Figure 8: Geologic map of the Cambrian Chao Nen and the Ordovician Tha Manao.

Figure 8.1: Geologic map
explanation and symbols
of the Cambrian Chao Nen
and the Ordovician Tha
Manao formations.

36 Sirot Salyapongse et al. / Thai Geoscience Journal 1(1), 2020, p. 27-46

The Cambrian-Ordovician rock sequence has and carbonate or matrix/cement components
been recognized for quite a long time being relative to detrital quartz and feldspar (Figs. 9-13).
extended throughout the western part of the Since it is a low grade and the generated rock
country or along the western Shan-Thai block. foliation is directly related to the original content
They characterize some transitional siliciclas- of the argillaceous material, the more it contains,
tic-carbonate facies of the Lower Paleozoic the better the foliated texture (see modal comp.
succession in Thailand. In most localities no. 1 and 3 in Table 5 and see Fig. 9 and Fig. 10)
observed, they are underlain by the inferred can be appreciated. In all of the samples,
Precambrian units and generally demarcated sedimentary relict texture and the original min-
by detachment planes which orientated eral phases are still recognizable although slight-
northwestward. The Chao Nen meta-sandstone ly modified by replacements or recrystallization
and the Tha Manao meta-limestone units are well of sericite after clay mineral/feldspar in noncar-
exposed along road-cut outcrops near to the bonated sandstone and authigenic replacement
Srinagarindra dam (Fig. 8) which situated in of calcite after quartz and feldspars in calcareous
Khuen Srinagarindra 1:50,000 map sheet. sandstone (Fig. 13). The incipient low-grade
regional metamorphism is locally indicated by
IV-1. Petrographic analysis of the Chao Nen the inconsistent development of the foliation as
and the Tha Manao siliciclastic sandstones well. In terms of metamorphic zoning, the occur-
Petrographic examination of the Cambrian rence of sericite in the Chao Nen sandstones
low-grade meta-feldspathic sandstones suggested considered successively lower grade than the
that their differences in mineral compositions are biotite-muscovite zone of the Upper Thabsila (Fig.
basically related to the variation in argillaceous 7 and Fig. 9).

Figure 9: KSn 171880 (no. 2) XPL. The Cambrian
Chao Nen meta-sericitized feldspathic sandstone
showing faintly oriented texture defined by a smaller
and minor amount of recrystallized sericite crystals
which restricted to the grain boundaries. Note the
grain supported with subangular shape nature and
minor content of the very fine-grained silica cement
plus a lesser amount of inter granular sericite crystals.
Probably due to this specimen was originally
relatively less argillaceous/clayey material and lower
grade of metamorphism so that its foliation is
not obvious. Accessory detrital zircon is frequently
observed. (KSn = Khuean Srinagarindra 1:50,000
sheet).

Figure 10: KSn 141932 (no. 7) XPL. Cambrian
meta- sericiticitized feldspathic sandstone.
It illustrates angular to irregular grains with very
fine-grained matrix support and foliated texture
defined by recrystallized white mica which in parts
replaced after feldspar grains, possibly formed
during the transition from diagenesis to low-grade
regional metamorphism. A bigger muscovite grain is
possibly detrital muscovite. Note the matrix-supported
texture probably originally was argillaceous rich
now has been recrystallized mainly to micro quartz
and foliated white mica. (KSn = Khuean Srinagarindra
1:50,000 sheet)

Sirot Salyapongse et al. / Thai Geoscience Journal 1(1), 2020, p. 27-46 37

Figure 11: KSn 141931 (no. 3) PPL. Showing
a Cambrian Chao Nen meta sericitized
feldspathic sandst one compris es higher relief
feldspar grains after HF etching to facilitate
point counting. (KSn = Khuean Srinagarindra
1:50,000 sheet)

Figure 12: KSn 141931 (no. 3) XPL. At the
same po sition. Note the development
of sericite faintly oriented within the rare
matrix part of the meta sericitized feldspathic
subarkose. All the detrital feldspar became
extinct. (KSn = Khuen Srinagarindra
1:50,000 sheet)

Figure 13: KSn 180918 (no. 5) XPL. Ordov
ician calcareous feldspathic sandstone.
It shows cement/matrix supported and non
foliated texture probably due to carbonation
and the rarity of argillaceous material.
Note the replacement boundaries of
feldspars and quartz (at extinction) by calcite
caused the irregularity in grain shape and
the reduction in grain size against the
replacing calcite. Although calcite appears
extensively replaced after quartz and
feldspars, this sample will also be included
for point counting for a comparison.
(KSn = Khuean S rinagarindra 1:50,000
sheet)

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V. Results and discussions
V-1. Modal classification and provenance of the Upper Thabsila, the Chao Nen and the
Tha Manao meta-siliciclastic sandstones.

Table 4. Modal compositions of the Thabsila complex.

No. Grain Sorting Foliated Quartz Feldspar Lithic Others Recalculated
size Quartz Feldspars Lithic

1 coarse mod. yes 78.33 5 0 16.67 94 6 0
(bi,ms,gar,op)

2 med. mod. faintly 89.67 3.67 0 6.67 (bi) 96.07 3.93 0

3 fine well yes 84.33 0 0 15.67 100 0 0
(bi,mus,zr) 0

4 fine well yes 91 0.67 0 8.33 99.27 0.73
(ms,bi,tur,py,

zr,op)

5 med. mod. yes 90.67 2.33 0 7 (bi,ms,zr,op) 97.49 2.51 0

6 med. mod. yes 87 20 11 97.75 2.25 0

(ms,bi,py, zr,op)

Abbrev.: ms = Muscovite, ser = Sericite, tur = Tourmaline, op = Opaque and Zr = Zircon

It can be mentioned shortly from the modal metamorphic origin (Table 4). Orientation
analyses (Table 4) that, the samples contain and recrystallization of the metamorphic
a significant amount of quartz while the lithics, micaceous minerals are the product of regional
if originally available, must have all been metamorphism in the later period subsequence to
destroyed during the transportation. Feldspar is diagenesis. Types of the micaceous mineral
not high signifying these feldspars from the mode developed in both of the Thabsila and the Lower
were the leftover from weathering and erosion Paleozoic rocks can be equilibrated with
of the protolith. The other significant constituent the original content and chemistry of the clay
is the micaceous minerals, biotite and muscovite, matrix in the former siliciclastic sandstones
which most of them represented the regional studied.

Table 5. Modal compositions of the Chao Nen Cambrian meta-sandstones and the Tha
Manao Ordovician calcareous sandstone (no.5), Kanchanaburi province.

No. Grain Sorting Foliated Quartz Feldspar Lithic Others Recalculated
size Quartz Feldspars Lithic

1 med. mod. yes 84.5 12.5 0 3 (ser,ms,op) 87.1 12.9 0
2 med. well faintly 89.0 10.0 0
3 med. mod. yes 85.7 11.3 0 1(ser,zr) 89.9 10.1 0
4 fine mod. yes 87.2 8.8 0
5 med. well None 72.0 8.0 0 3 (ser,tur,op) 88.4 11.6 0

0 4 (ser,ms,op) 90.8 9.2

0 20 (calcite 86.3 13.7
cement)

6 fine well. None 77.0 22.0 0 1 (ser,ms,tur,zr) 77.8 22.2 0
7 fine mod. yes 71.5 25.5 2.25 0
8 med. well None 79.0 20.0 0 3 (ser,ms,op) 97.75 20.2 0

0 1 (ser,op) 79.8

Abbrev.: ms = Muscovite, ser = Sericite, tur = Tourmaline, op = Opaque and Zr = Zircon

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Comparatively the same reading about the the Upper Thabsila. It may be useful as a support
modal analysis result of the Lower Paleozoic for a continuous depositional environment
rocks as that of the Upper Thabsila sequence between the Upper Thabsila and the Lower
can be apparent here as well. The percentage Paleozoic sequence. Notably, all these meta-
of quartz is more or less similar to the Upper siliciclastic sandstones are devoid of any rock
Thabsila complex. Feldspar is significantly fragment.
higher. Micaceous minerals are lesser. Tourmaline, The nonuniform foliation development and
considered to represent a metamorphic phase, is the textural remnants of a diagenetic process
available in this Lower Paleozoic meta-siliciclastic (Figs. 9 and 10) in the Chao Nen, may suggest
sandstone as well as that was already noted from lower grade metamorphism

V-2. Modal classification and provenance of the Upper Thabsila
and the Lower Paleozoic meta-siliciclastic sandstones

Figure 14: A Quartz-Feldspar-Lithic ternary diagram modally classified altogether the
studied met-siliciclastic sandstones to show an evolution in modal composition
relatively to their stratification (Folk,1980).

Modally the mineral volume percentages withlesser amount of the original clayey matrix
as counted and recorded as QFL percent suggest (Figs. 6 and 7). Continuation to the Lower
the compositional classification spanning from Paleozoic sequence, the sedimentation seems
arkose to subarkose and quartz arenite. Considering continuing from the more mature (sample no. 1),
in detail about the degree of maturity relative to i.e. from subarkose toward the less mature,
lithology from the older to the younger beds, the arkose (sample no.7 in Fig. 14). Other
the Thabsila samples are starting mainly with than for the modal classification of all the
a lesser mature composition, i.e. subarkose (no. 1, meta-siliciclastic sandstones, the same modal
Fig. 14) probably with a higher percentage plot can also be used as a provenance categori-
of feldspar and the least quartz content (the zation of the source terrane. All of the meta-
sample numbers are running consecutively siliciclastic sandstones studied illustrate a
from older to younger beds), then evolving continental block setting. They share the same
further to quartz arenite, i.e., much more mature provenance.

40 Sirot Salyapongse et al. / Thai Geoscience Journal 1(1), 2020, p. 27-46

Figure 15: A Quartz-Feldspar-Lithic ternary diagram showing provenance
classification basing on the same plot as that of Fig. 14 with the superimposed
provenance categories of all the studied meta-siliciclastic sandstones (Dickinson
et. al,1983).

V-2.1 Geochemical analyses by XRF of the Upper Thabsila, the Chao Nen and the Tha Manao
meta-siliciclastic sandstones.

Table 6. XRF chemical analyses of major oxides from the Thabsila meta-siliciclastic.

Thabsila Sequence

Oxide 1 Samples 5 6 Aver.
67.41 2 34 96.51 96.04
SiO12 14.90 2.266 2.37 89.796667
Al2O3 0.49 90.63 92.31 95.88 0.149 0.1657 5.1588333
TiO2 0.5603 0.04371 0.00 0.2537667
CaO 6.072 4.822 4.446 2.149 0.5885 0.5474 0.12767
1.879 0.00 0.00 1.66455
Fe2O3 7.499 0.2478 0.2088 0.2613 0.3313 0.6726 0.4816167
Na2O 0.00 0.00 0.00 2.0880667
K2O 0.779 0.1157 0.04631 0.00 0.00 0.08686
FeO 0.00 0.00 0.00 0.00
0.03182 1.236 0.9419 0.6015 0.02482 0.02823 0.2276767
MgO 0.1021 0.00 0.00 0.0058417
0.00 0.2304 0.7803 0.00 0.04481 0.0429 0.0337267
SO3 0.0209883
ZrO2 2.283 0.9112 0.8313 0.0358833
P2O5
Cr2O3 0.00 0.00 0.00

0.2999 0.2003 0.00

0.01137 0.00 0.02368

0.03512 0.04323 0.03914

0.00 0.02383 0.00

0.04028 0.03337 0.05394

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Table 7. XRF chemical analyses from the Chao Nen and the Tha Manoa meta-siliciclastic.

Chao Nen and Tha Manao

Oxide 1 2 Samples 5 6 Aver.
90.98 91.74 34 72.97 87.04
SiO12 4.04 3.67 87.23 89.43 3.64 5.68 85.74125
Al2O3 0.18 0.2 6.07 5.18 0.19 0.18 5.5325
TiO2 1.1 0.1 3.67 0.32 15.77 0.00 0.63375
CaO 0.87 0.32 0.29 0.03 1.14 0.78 2.20375
Fe2O3 0.00 0.00 0.62 0.7 0.00 0.00 0.89
Na2O 1.97 1.74 0.00 0.00 1.8 3.51
K2O 0.00 0.00 2.69 1.91 0.00 0.00 0
FeO 0.09 0.00 0.00 1.41 0.19 2.71625
MgO 0 0.00 0.26 0.29 0.00 0.00
SO3 0.00 0.00 0.00 0.00 0.02 0.02 0
ZrO2 0.02 0.05 0.07 0.06 0.08 0.00 0.365
P2O5 0.00 0.16 0.00 0.00 0.00
Cr2O3 0 0.00 0.00 0
0.00 0.03
0.06

0

When considering the inconsistency in a 7), the Na2O content is only available in the
rock name between the different classification Thabsila no. 1 to 3 and never reappear again
methods of the no.1 Thabsila meta-sandstone even in the Lower Paleozoic rocks. These
(Figs. 14 and 16), it tells subarkose in mode, features probably were related to both original
while its chemical plot suggests wacke. This source rock compositional control as well as
disagreement can be realized from the current nature of the transporting medium and the
availability of micas, garnet, fibrolite, and weather condition at the time. Another deviated
other accessories which have not been plotted plot has been observed also with the Lower
in Figure 14. All these minerals considered Paleozoic rock sample of no.5. Its deviation
to be a derivative from the original muddy (Fig. 19) is considered to be the result of the the
sandstone (or wacke sandstone) before it was presence of calcite replacement after quartz and
metamorphosed to sillimanite-garnet-micas feldspar and from its availability as the cementing
schist. From the chemical analysis (Table 6 and non-silicate Ca bearing mineral (Fig. 13).

42 Sirot Salyapongse et al. / Thai Geoscience Journal 1(1), 2020, p. 27-46

V-3. A chemical classification diagram of the Upper Thabsila, the Chao Nen and the
Tha Manao meta-siliciclastic sandstones.

Figure 16: A geochemical classification diagram for the studied
meta-siliciclastic sandstones. (after Herron, 1988)

All the sample populations of both the Thabsila content. The amount of biotite also reflects
complex and the Lower Paleozoic formations the Al2O3 and K2O content in the analyses.
are compositionally separated in 2 superimposing Another important supplier of the Al2O3
asymmetric cycles both are striding the fields is significantly from the feldspars but only
of chemical lithologies ranging from wacke to K-feldspar will provide a significant amount of
subarkose to quartz arenite for the Upper Thabsila. K2O. All these are the variability between
The Upper Thabsila rocks are compositionally the amount of the mineral phases or mode,
richer in Fe2O3 as indicated by the occurrence correspondingly reflected the amount of the
of many iron-rich minerals such as biotite, garnet, major oxides from the chemical analyses of the
and opaque iron ore. Compared to the plot of same rocks to cross-check if either of them can
the Lower Paleozoic, they are lower in Fe2O3 be reasonably correlated.

V-3.1 A tectonic setting discrimination diagram of the Upper Thabsila, the Chao Nen and the
Tha Manao meta-siliciclastic sandstones.

Figure 17 : A tectonic discrimination diagrams (after Bhatia, 1983)
for the studied rocks.

Sirot Salyapongse et al. / Thai Geoscience Journal 1(1), 2020, p. 27-46 43

Figure 18 shows most of the samples depicting rock units as well as illustrating in the same
a passive margin tectonic setting. The deviated fashion to all of the other diagrams (comparing
plot of the Thabsila no1 was due to its composition Figs. 15 and 19). Most of the Upper Thabsila
is more immature, containing more mafic mudrock and the Lower Paleozoic rocks are generally
in the matrix now represented by an increase in plotted within the moderate weathering regime.
the amount of biotite and muscovite among The trend of the Upper Thabsila is reached
quartz and minor feldspar with additional other the intensive weathering zone by no.5, an
minor silicates and iron opaque. More collection indication that the no.5 was extensively
of similar samples would fill in the Thabsila affected by the intense weathering clearing the
sample populations. original fine-grained materials to the best
maturity in the younger sequence far more
V-4. Degree of weathering of the Upper maturer than the older beds. (See Fig. 18 of
Thabsila, the Chao Nen and the Tha Manao Thabsila no. 4, 5, and 6) for a comparison.
source materials. The Thabsila no. 1 is again also far more
This is more or less showing the plot deviated but approximately in the same trend.
populations are trending in a linear line sloping While the Lower Paleozoic samples appear less
from the low weathering or more immature obvious but roughly showing a cyclic returning
toward the intensively weathering or the more from the more weathering regime continuation
mature end. The repeated asymmetric cyclic from the Thabsila towards less weathering
evolution is also can be apparent to both of the in the younger beds.

Figure 18: Chemical index of alteration (CIA)
of sandstones and its correlation with Al2O3
(after Bonjour and Dabard, 1991).

V-5. Degree of maturity of the Upper Thabsila, the Chao Nen and the Tha Manao source materials.

Figure 19: Chemical maturity of the sandstones
expressed by the bivariate plot of SiO2 versus
Al2O3+ K2O+ Na2O (After Suttner and Dutta,
1986).

44 Sirot Salyapongse et al. / Thai Geoscience Journal 1(1), 2020, p. 27-46

Chemical composition spreading of all beds as can be stratigraphically observed. (See
the studied meta-siliciclastic sandstones can be the geologic maps, of Fig. 2 and Fig. 8).
seen in (Figs. 18 and 19) as they distributed To appreciate the degree of chemical
in the way as to indicate the cyclic repetition maturity, it can be understood that, the deviated
suggesting rhythmic or cyclic sedimentation. plot of the Tha Manao calcareous siliciclastic
They have been more or less evolving in the same sandstone (no.5) which bears a significant
trend which assuming a repeated compositional amount of the non-silicate carbonate, the
variation (silica relative to the Al2O3+K2O Ca bearing phase (Table 5) as well as their
+Na2O) both in the Thabsila and the Lower authigenetic replacement would cause the
Paleozoic formations. The inclining ratio ranging discrepancy behavior of the no5 in this diagram.
from SiO2 66% towards 100% (Fig. 19) suggests Trending of the meta-siliciclastic plots reflect
all the sample populations of both lithologic the cyclicity of each rock unit during their
groups were of the cyclic evolution starting from sedimentary evolution from the more immature
sub-mature or wacke composition up to super towards the more mature and turning back
mature in the Thabsila and then continue a reflecting the more humid weather than the
repetition of an asymmetric cyclic from more arid. (Fig. 19 and Table 4, 5 and Table 6, 7)
maturity in the lower horizon of the Lower in an asymmetric (A→ B→ C→ D, A→ B→
Paleozoic to gain lesser maturity in the younger C→ D) fashion.

V-6. Type of source rocks of the Upper Thabsila, the Chao Nen and the Tha Manao

Figure 20: Geochemical classification
of igneous source rocks. (Le Bas et al. 1986)

It can be further discussed in the chemical interpreted from the modal and the chemical
variation shown in Figure 20 relative to the analysis as follows. Since there is no record
modal analyses tabulated in Table 4 and 5 and of any lithic in all of the meta-siliciclastic
geochemical analyses in Tables 6 and 7. sandstones studied, source rocks of them
The variation of SiO2 which mainly extracted were not very likely derived from the fine
from the silicate mineral i.e. dominantly to very fine-grained volcanic and other
was from quartz with a minor variation from rocks, but rather from the less resistance
the content of the feldspar and micaceous coarser-grained plutonic or gneissic rocks.
minerals (see Table 4 and 5). The trend moves For the Thabsila meta- siliciclastic sandstones
toward 100% SiO2. While the content of Al2O3/ which contain Na2O only in the immature or
TiO2 also declines from about 30 % to 5% sub-mature samples, but not in the mature
suggesting a more maturity and the elimination ones, may reflect the source rock was less
of feldspar and finer clay-rich material during felsic and contain plagioclase which has
their evolution of the Thabsila than the Lower been destroyed leaving only the finer clay
Paleozoic formations. material in the younger sequence during
Considering the felsic types of source rock moreweathering or uplifting of the source
material as indicated in Figure 20, it can be terrane.