Brachiopod site of the ao nam area, laem sak subdistrict, ao luek

106 Pages·2013·40.42 MB·English

Technical Report
No. BFP. 3/2012

BRACHIOPOD SITE
OF THE AO NAM AREA,
LAEM SAK SUBDISTRICT, AO LUEK DISTRICT,
KRABI PROVINCE, SOUTHERN THAILAND

Bureau of Fossil Protection
Department of Mineral Resources
Technical Report
No. BFP. 3/2012

BRACHIOPOD SITE
OF THE AO NAM AREA,
LAEM SAK SUBDISTRICT, AO LUEK DISTRICT,
KRABI PROVINCE, SOUTHERN THAILAND

Dhanyadhorn Thonnarat
Watsamon Puangmalai
Napaporn Tibphad

Bureau of Fossil Protection
Department of Mineral Resources
Director General – Department of Mineral Resources
Mr. Nitat Poovatanakul

Director – Bureau of Fossil Protection
Mr. Winat Phuthiang

Director of Mineral and Rock Museum Ms. Dhanyadhorn Thonnarat

Printed by Bureau of Fossil Protection

Department of Mineral Resources
Rama VI Road, Ratchathewi,
Bangkok, 10400, THAILAND
Tel. [phone]
Fax. [phone]

First Edition March, 2012
5 Copies

Bibliography Information

Dhanyadhorn Thonnarat

Watsamon Puangmalai

Napaporn Tibphad

Brachiopod Site of the Ao Nam Area, Laem Sak Subdistrict,

Ao Luek District, Krabi Province, Southern Thailand / By Dhanyadhorn
Thonnarat, Watsamon Puangmalai, and Napaporn Tibphad .- - Bangkok
: Bureau of Fossil Protection, Department of Mineral Resources, 2012.
96 Pages
Technical Report No. BFP.3/2012
I

ABSTRACT

Marine Permian rocks belonging to the Khao Phra Formation of the Kaeng Krachan Group
are well exposed at Ban Ao Nam, Ao Luek District, Krabi Province, Southern peninsular Thailand. The rocks
are unconformably underlain by the Ko He Formation, but conformably overlain by the limestones of the
Ratburi Group. Lithostratigraphically, the sequence can be divided into five units, respectively in ascending
order: Ao Nam 1, Ao Nam 2, Ao Nam 3, Ao Nam 4, and Ao Nam 5, consisting mainly of sandstone,
siltstone, and mudstone with total thickness of approximately 77 m. These rocks contain faunal
assemblages of brachiopods, bryozoans, crinoids, and trilobite fragments, of which brachiopods are
abundant. Seven hundred and eighty six specimens of brachiopods have been collected and can be
identified into 38 species. Of these, Kutorginella cf. paucispinosaI and Chonetinella cf. andamanensis are
dominant and abundant with more than 100 specimens or 32% of the total specimens collected.
Orthotetes cf. perplexus, Stereochia cf. kaoyaoensis, Spiriferella cf. modesta, and Spinomartinia prolifica
range from 50-100 specimens or 39% of the total. Linoproductus sp is represented by 47 specimens,
constitutes 6% of the total. Stenoscisma cf. quasimutabilis, Anomaloria cf. glomerosa, and Hustedia cf.
ratburiensis are approximately represented by 25 specimens, constitute 10% of the total. Other species
include, less than 25 specimens or 13% of the total, Rhipidomella cf. cordialis, Schuchertella cf. cooperi,
Derbyia cf. scobina, Meekella cf. bisculpta, Perigeyerella cf. tricosa, Demonedys cf. fastigiata, Tornquistia
cf. tricorporun, Stictozoster cf. leptus, Comuquia cf. modesta, Dyschrestia cf. spodia, Marginifera cf.
nesiotes, Retimarginifera cf. alanta, Caricula cf. salebrosa, Bibatiola cf. costata, Celebetes cf. gymnus, Rigbyella cf.
crassa, Pontisia cf. exoria, Goleomixa cf. acymata, Cruricella cf. couria, Cleiothyridina cf. seriat, Composita
sp, Permophricodothyris cf. notialasistica, Brachythyrina cf. rectangulus, Grantonoa sp., Martiniopsis cf.
trimmata, Callispirina cf. austrina, Paraspiriferina, Hemiptychina cf. murrita. Based on faunal assemblages
and lithologies, the rocks have been interpreted as having been deposited in shallow marine and shelf
environments in the Early Permian age.
The presence of Early Permian brachiopods at Ban Ao Nam is classified as one of the
most important fossil sites in southern Thailand in terms of abundance and diversity. This site is not only
for academic study but is also suitable for promoting as a tourist site, and a fossil site under the Fossil
Protection Act., B.E. 2551.
II

CONTENSTS
ABSTRACT ………………………………………………………………………………………………………………. I
CONTENTS ………………………………………………………………………………………………………………. II
LIST OF FIGURES…………………………………………………………………………………………………………….. IV
LIST OF TABLES……………………………………………………………………………………………………………… V
LIST OF PLATES……………………………………………………………………………………………………………… VI
CHAPTER 1 INTRODUCTION……………………………………………………………………………………. 1
1.1 Objectives……………………………………………………………………………………………… 1
1.2 Workers………………………………………………………………………………………………….. 1
1.3 Planning…………………………………………………………………………………………………. 1
1.4 Study area……………………………………………………………………………………………… 2
1.5 Accessibility……………………………….………………………………………………………….. 2
1.6 Topography of the study area.….…………………………………………………………. 2
1.7 Topography of the fossil site……….………………………………………………………. 5
1.8 Previous works………………………………………………………………………………………. 6
1.9 Acknowledgements………………………………………………………………………………. 8
CHAPTER 2 GENERAL GEOLOGY………………………………………………………………………………. 9
2.1 Rock distribution…………………………………………………………………………………… 11
2.2 Structural geology……………………………………………………………………………. 16
CHAPTER 3 STRATIGRAPHY……………………………………………………………………………………… 18
3.1 Unit Ao Nam 1 – AN1……………………………………………………………………………. 23
3.2 Unit Ao Nam 2 – AN2……………………………………………………………………………. 25
3.3 Unit Ao Nam 3 – AN3……………………………………………………………………………. 27
3.4 Unit Ao Nam 4 – AN4……………………………………………………………………………. 29
3.5 Unit Ao Nam 5 – AN5……………………………………………………………………………. 31
III

CHAPTER 4 SYTEMATIC PALEONTOLOGY………………………………………………………………. 33
4.1 General information……………………………………………………………………………… 33
4.2 Brachiopods in general…………………………………………………………………………. 33
4.3 Systematic description of brachiopods……………………………………………….. 34
CHAPTER 5 CONCLUSIONS………………………………………………………………………………………. 79
5.1 The useful of brachiopods…………………………………………………………………… 79
5.2 Fossil site conservative and development…………………………………………. 80
5.3 Conclusions…………………………………………………………………………………………… 81
REFERENCES ………………………………………………………………………………………………………………. 83
APPENDIX ………………………………………………………………………………………………………………. 88
IV
LIST OF FIGURES
Page
Figure 1.1 Topographic map showing the Ban Ao Nam fossil site ……………………………………………… 3
Figure 1.2 Route to the brachiopods site at Ban Ao Nam …………………………………………………………… 4
Figure 1.3 Topographic map showing topography of the study area …………………………………………. 5
Figure 1.4 Satellite image showing topography of the Ban Ao Nam fossil site ………………………….. 6
Figure 1.5 Photograph showing the Ban Ao Nam fossil site ………………………………………………………… 6
Figure 2.1 Geological map presented distribution of the rock units in Changwat Phangnga
Quadrangle (4725 IV) ………………………………………………………………………………………………….. 9
Figure 2.2 Geological map showing distribution of the rock units within the study area …………. 10
Figure 2.3 Photograph showing karst topography of the Permian limestone; Ratburi Group …… 11
Figure 2.4 Photograph of an outcrop of the Lam Thap Formation south of Ban Sai Dam ………. 12
Figure 2.5 Photograph showing outcrops of the Lam Thap Formation at the road no.4039 …… 13
Figure 2.6 Photograph showing the geologic column of the Lam Thap Formation at the road
no.4039 from Ao Luek to Laem Sak ………………………………………………………………………….. 14
Figure 2.7 Photograph showing siltstone, mudstone interbedded with sandstone at the Ban
Sai Dam ………………………………………………………………………………………………………………………….. 15
Figure 2.8 Photograph showing the faults in the Lam Thap Formation at Ban Sai Dam ………….. 16
Figure 2.9 Photograph showing anticlinal folding in the Lam Thap Formation …………………………. 17
Figure 3.1 Graphs showing brachiopods distributed in each unit of the Khao Phra Formation …. 20
Figure 3.2 Photograph showing the geologic column of the Khao Phra Formation at the study
area of Ban Ao Nam ……………………………………………………………………………………………………… 22
Figure 3.3 Line of measured section of the Khao Phra Formation at the proposed research
area of Ban Ao Nam ……………………………………………………………………………………………………. 23
Figure 3.4 Photograph showing layers where faunas have been collected in unit AN1……………. 24
Figure 3.5 Photographs of unit AN2 of the Khao Phra Formation appeared on sandstone’s
surface ………………………………………………………………………………………………………………………… 26
Figure 3.6 Photographs of unit AN2 showing brachiopods exposed on in the rock surface …….. 26
Figure 3.7 Photographs of unit AN3 of the Khao Phra Formation ………………………………………………. 28
Figure 3.8 Photographs of unit AN4 of the Khao Phra Formation ………………………………………………. 30
Figure 3.9 Photograph of unit AN5 of the Khao Phra Formation ………………………………………………… 31
V

LIST OF TABLES
Page
Table 3.1 Brachiopod distribution at the Ao Nam village ………………………………………………………… 19
Table 3.2 Genera from the Rat Buri limestone shared with Texas …………………………………………. 20
Table 3.3 Brachiopods’ species at the unit AN1 ………………………………………………………………………. 25
Table 3.4 Brachiopods’ species at the unit AN2 ………………………………………………………………………. 27
Table 3.5 Brachiopods’ species at the unit AN3 ………………………………………………………………………. 29
Table 3.6 Brachiopods’ species at the unit AN4 ………………………………………………………………………. 30
Table 3.7 Brachiopods’ species at the unit AN5 ………………………………………………………………………. 32
VI
PLATES
Page
Plate 1 Orthotetes cf. perplexus, and Derbyia cf. regularis…………………………………………………….. 36
Plate 2 Rhipidomella cf. cordialis……………………………………………………………………………………………... 38
Plate 3 Meekella cf. bisculpts………………………………………………………………………………………………….... 40
Plate 4 Tornquistia cf. Tricoporun and Chonetinella cf. andamanensis………………..……………... 42
Plate 5 Stictozoter cf. leptus ?...............................................................................................……………... 44
Plate 6 Dyschrestia cf. spodia…………………………………………………………………………………………………... 46
Plate 7 Marginifera cf. drastic………………………………………………………………………………………………….... 48
Plate 8 Retimarginifera cf. alanta……………………………………………………………………………..…………….... 50
Plate 9 Caricula cf. salebrosa sp…………………………………………………………………………………………….... 52
Plate 10 Kutorginella cf. paucispinosa……………………………………………………………………….…………….... 54
Plate 11 Stereochia cf. koyaoensis sp………………………………………………………………………..…………….... 56
Plate 12 Linoproductus sp…………………………………………………………………………………………..…………….... 58
Plate 13 Stenoscisma cf. quasimutabilis sp……………………………………………………………….…………….... 60
Plate 14 Cleiothyridina cf. seriata……………………………………………………………………………….…………….... 62
Plate 15 Anomalaria cf. glomerosa…………………………………………………………………………….…………….... 64
Plate 16 Permophricodothyris cf. notialasistica…………………………………………………………………………. 66
Plate 17 Brachythyrina cf. rectangulus……………………………………………………………………….……………... 68
Plate 18 Spiriferella cf. modesta and Grantonia sp………………………………………………….……………..... 70
Plate 19 Martiniopsis cf. trimmata……………………………………………………………………………………………... 72
Plate 20 Spinomatinia prolifica…………………………………………………………………………………..…………….... 74
Plate 21 Callispirina cf. austrina, and Hustedia ratburiensis…………………………………….…………….... 76
Plate 22 Hemiptychina cf. murrita…………………………………………………………………………………………….... 77
Plate 23 Bryozoans, Crinoid, Coral, and Trilobite……………………………………………………………………… 78