Fossil Biodiversity in the Limestones of Thailand: A Cornucopia of Information about the History of Life

2005·1.8 MB·English

by  Fontaine, Henri

NAT. HIST. BULL. SIAM Soc. 53(1): 33-70，2 005
FOSSIL BIODIVERSITY IN THE LIMESTONES OFT HAILAND:
A CORNUCOPIA OF INFORMATION ABOUT THE HISTORY
OF LIFE
Henri Fontaine1，Si rot Salyapongstl and Varavudh Suteethorn3
ABSTRACT
In Thailand，fo ssiIsar e common and diverse.百eycome from bo血terrestriaIand m紅泊E
environments.τ'hey belong to many t泊施periodsbeginning with the Cambrian，血usspann泊g
more血an500 miIIion years (白ePhanerozoic eon).明lisrich past emerges台。mextensive
pubIished data and is stiII very in加estingto explore.
明lispubIication concems only fossiIsi ncluded in Iimestone deposited in白巴seasof the
past. Lim巴stoneis widespread泊百ailandand of various 格的.Marine floras (aIgae) and
faunas釘宮 inabundance at many Iimestone exposures飢dtheir skeletons ar草加 impo此釦I
component of血.elimestone.百leygive ad eep-time perspective on the evolution of the Iife in
出eseas of血.epast.
τ'heIi mestones of ThaiIand are not res町ictedto出ewidespread exposures visible on th巴
land. They have been found by hydrocarbon exploration at varjed depths and in different are鎚.
Permian Iimestone has been reached by weIlsu nder the Khorat Plateau and its extent has been
determined by seismic interpretation; it is widespread (for instance，se e MOURET，19 94). This
pubIication is concemed only wi出 l加estonesexposed at ground surface. Limestone is a
generaI term for diverse types of rocks，de posited in different environments. Before describing
their biodiversity，w e discuss the orig泊。f出eIimestones of τ'haiIand.
Key words: Diversity，fo ssiIs，li mestone，m 悩sextinctions，pa Ieogω，graphy，s回 .tigraphy，百lailand
LTh庄ESTONESOFT HAILAND
In Thailand，l imestone (HinP un in百lailanguage) is ar ock very widespread at the
surface of the land all over血ecountry. It makes up small to very large hills，w hich are
locally numerous，fo r instance north of Saraburi between Lopburi and MuakL ek. Beautiful
landscapes have been carved by erosion，p roducing am arvellous castellated topography.
Caves紅.ecommon. In addition to the prominent hills，sm alllimestone outcrops釘escattered
at ground surface.τ'hey are not visible in the topography，bu t easily seen in the banks of
the rivers as well as in ponds or other holes dug by f，創mers.
Limestone is known by everybody and m佃 yhills紅ecalled Khao Hin Pun or simply
Khao pun (= Limestone Hill). In other places，th e names show the imagination of the local
peοple; they describe the peculi釘 topographyof the limestone (k紅sttopography; see Figs.
1，4 to 6). Many hills are called Khao百lamor Khao Khuha (= Hill with a Cave). A
qualifier may be added because of組 undergroundriver (Khao百四nNamL ot)，a p eculi釘
18 aIlee de la ChapeIle，9 2140 Clamart France
2143 Moo 6，S oi Pinnakom 4，B orommaratchachonnari Road，B angkok 10170，T haiIand
30eologicaI Survey，D ep釘飢lentof MineraI Resources，R ama IV Road，B angkok 10400，τ'haiIand
Received 8N ovember 2004; accepted 16 May 2005.
33
34 HENRI FONTAINE，S IROT SALY A PONGSE AND VA RAV UDH SUTEETHORN
feature (Khao Suwana Khuha = Hill of the Gold Cave)，or the size (Khao Tham Yai or
=
Khao Tham Luang Hill of the Large Cave). Khao Laem indicates ap ointed hill. Phu
Tum means ab ud shape; it is ac ommon name in Loei Province. Doi Sam Sao (Hill of the
百rreeTriangles)，b etween Chiang Dao and Phrao，di splays 3a ngular points of limestone
standing out from its top. Limestone hills are commonly steep-sided; Khao Pha Daeng is
ah ill with ar ed cliff，K hao Pha Dam is ah ill with ab lack cliff，K hao Pha Lat is ah ill
with an inclined cliff，K hao Lak is ah ill surrounded by cliffs and showing am ilestone
shape. Khao Wong is ah ill with as inkhole at its centre. When the limestone is clearly
bedded，it is compared to ap ile of folded clothes (Khao Phap Pha). Khao Phap Pha is a
common name in Surat 官laniProvince (see Fig. 3).
Then ames of other hills are focussed on the flora or the fauna of the hills: Khao Ruak
(Hill of as mall kind of bamboo)，K hao P耐ik(Hill of the Red Pepper)，K hao Pha Fai (Hill
with ac liff and cotton)，K hao Kw ang (Hill of the Deer)，K hao ThamI kea (Hill of the Cave
of the Bats)，K hao Lan (Bald Hill，wi thout vegetation). Many species live in karst topography
at the surface of the hills or in the caves which are common in limestone hills.
Types of Limestone
Limestone is commonly grey to black，bu t locally it may be white，y ellow or red. It
is massive or thinly to thickly bedded (Figs. 1t o 6). It is fine-to coarse-grained. From a
chemical point of view，it is almost pure carbonate of calcium deposited in ac lean
environment; this is the case at many localities of Thailand. However，th is is not the rule;
clay and even sand locally occur in the limestone，oc casionally in such aq uantity that the
appropriate names of the rocks become calcareous shale or calcareous sandstone. Limestones
are polygenetic; they were deposited in differing environments which will be described
below. In these different types of rocks，f ossils are commonly well preserved. Their
abundance dis佐ibutionsand their diversities reflect the images of ancient living communities，
with some fidelity.
After its deposition，li mestone has been transformed by different diagenetic processes
which were destructive or constructive. It may have been dolomitized; then，it displays a
fair content of magnesium. In the field，do lomitic limestone is easy to recognize because
its surface is not smooth，bu t looks like elephant skin. Dolomitization commonly destroys
the fossils and precise identifications are impossible. When limestone has been heated by
intrusion of igneous rocks，it is recrystallized and the fossils eagain largely or entirely
紅
destroyed. In dolomitized and recrystallized limestones，th e original characters 'eobscured
訂
or erased. These rocks are not helpful in reconstructing life of the past and they are locally
difficult to date. They are fortunately restricted to small areas of Thailand.
Depositional Environments
Limestone has been deposited almost everywhere in τbailand加marineenvironments，
and commonly in distinct subenvironments of shallow seas. An exception has been
recognized (IWA I，1 972 and 1973)，a f ew limestone beds at the base of the Khorat Group
in Northeast Thailand have been considered lake deposits; they紅'ethin，le ss由加 10cm
thick，wi th the exception of ab ed reaching 2m in thickness. This limestone is practically
barren of fossils. Lacustrine faunas ecommonly of low diversity. Such deposits are
ぽ
FOSSIL BIODIVERSITY IN THEL 1MESTONES OF THAILAND 35
Figllre 1. Limestoneh illsn earN all1 PiyangD in Waterfa llsOlllh 0 '1WangS aphllng in Lo巴iProvinceパlorlheaSlell1
Thaliand. Theil ll1eSl0ne，E arlyP ermian in age，c onlains ll1anyf orall1inifera(s ll1allerfo raminiferaa n lc
fusulinaceans). It isa lso richi n caIcispheres and Tllbip/り刊sfragll1enls; coralsa rer al巴(FONTlfINEti
AL.，2 002，a nd in pl巴paration)
Figure2 . Beddedl im巴stoneatK oS iC hangn earV ashiravlll Bridge. KoS iC hangi sa ni sland 0 '1lh巴northeaslel日
part of theG ulf0 '1Thaliand.T h巴illl1esloneisp artlyr ecrystallizeda ncl poorin fosslis( SflLYflPONGSE
ETA L.， 2002); it isc onsiderecl Ordovician in ag巴
36 HENRIF ONTAINE，SI ROT SALYAPONGSE AND VARAVUDH SUTEETI-IORN
Figllres 3. 8edded limeston巴satt wo differel1l hills.
a: Permian lil1lestoneh ill of SlIrat Thani
Province in Peninsular Thailand.T he
limestonei sc1 earlyb edded. II isc Ol1lpared
to ap il巴offoldedc 101hes (Phap Pha)a nd
called KhaoP hap Pha (Hill of th巴Folded
Cloth巴s).lt isl ocally rich in fossils，bl ll
of a low diversily.b: Khao Pha Wak，a
hill south of lhe road 'from Tak 10 Mae
SOI. The lil1leSlon巴ispoor in fosslis.T his
hill has a cave and is historically
interesting; itw as a hiding place '101
soldiersd llring World War Il
FOSSIL BIODIVERSITY IN THE LIMESTONES OF THAILAND 37
Figures 4. Limestone hills at a Buddhist temple before
arriving at the Nam Pi yang Din Waterfall. a:
Thickly bedded limestone at a hjll near the
temple. b: The same limestone, eroded, at
the entrance of the temple.
38 HENRIF ONTAINE，S IROT SALYAPONGSE AND VARAVUDI-IS UTEETHORN
Figllre5 . Khao Thalll Kracha巴ng，hillo f san Nang Sata al巴ain sOllth巴rnmostThailand，w ith an und巴rground
tunn巴1followed by ar iver. The lilllestone ism assiv巴andrecrystalliz巴d.
Figure6 . DoiP haC hu (18・23'15"N，100・48'55"E)in Na Noia rea ofN anP rovince. Massive lillleston巴cont白川川g
'Iossilsi n llloderateq llantity: algae，fa sciculatec orals，s ponges，b ryozoansa ncl bivalves (FONTAINE ET
AL.，2 001)
FOSS且 BIODIVERSITYIN THE LIMESTONES OFT HAILAND 39
known in lakes of North America，o ccurring under different sets of circumstances. In
addition to the limestone of the Khorat Group，ca liche，tr avertine and ωfa can be mentioned.
τbey are te'estrialcalcareous materials of secondary accumulation，kn own at many localities
町
of Thailand;出ey釘'etoo small in space and too restricted in time to be very interesting.
However，出istype of rock has recently a町actedattention at Khao Si Siet，a h ill built up
by unconsolidated pebbly alluvial deposits，no rth of Amphoe Lao Kwan泊 thenorthem
p釘tof Kanchanaburi Province. Polished仕agmentsof carbonate material formed泊 these
deposits give beautiful pieces of marble，oc casionally containing land snails. In addition to
出at，fissure fillings紅ecommon at the limestone hills of Thailand; they locally contain
fossils such as skeletons of Quatemary terres凶alvertebrates (for instance，se e CHAlMANEE
ETA L.，1 996，fo ssils from Khao Sam Ngam near Ratb町i).
1n the geologic record，li mestone is commonly absent企omdeep sea deposits. However，
it is occasionally represented by由加turbiditebeds，ca lled allodapic limestone. Fossils are
not in their original place，白eywere transported from shallow areas and transfer冗dto
ba白川 depths.1n Cen佐alThailand，th is type of rock (Nam Duk Formation) has been
described along the road from Lom Sak to Chumphae，es pecially ne milestone17.2 km
紅
(HELMC阻 &KRAI阻 ONG，1982); it contains ap oor allochthonous fusulinacean fauna.
Shallow water marine limestone is extensive in Thailand. It has been commonly
deposited in well oxygenated water，i lluminated by day-light，at suitable salinity and
temperature. Great numbers of fossils with high diversity suggest favourable environments.
Thes hallow depth of白ewater is indicated by the occurrence of green algae at many
localities. Warm water is suggested by the abundance of 1gecompound corals at many
釘
Devonian to Jurassic localities.
Some limestone formations are白ick;they were continuously deposited during al ong
t泊施， in the same environment. They consist of accumulations of skeletal material as well
as organically induced accumulations of other types of carbonate material. Some organisms
encrust or attach to one another;白eylocally built up ar igid mass even before fossilization.
τbe environment was locally energetic，w ith strong waves increasing the supply of
food and oxygen. Many organisms could thrive easily. But after由自dea出，their skeletons
were often broken by the turbulent water，b ut commonly泊 nottoo small仕agments，出us
allowing good In some places，th e fossils and their debris were accumulated
identifi~ation.
in de甘italmounds，la ter on consolidated by inorganic cementation. Reefs were commonly
wave-resistant.百lelimestone produced in energetic environments is formed mainly of
grains and skeletal debris. However，m odem sea-grass is regarded as protecting lime-mud
buildups; the size of the grain must not be always conside問daccord泊gto the water
turbulence.
Environment was more or less quiet in other areas. Limestone is fine-grained. 1t is
locally ultrafine-grained，cl ay-sized carbonate and it is called micstone. Fossils ebetter
釘
preserved，bu t they are commonly less diverse and less abundant. They may be almost
absent where water was confined to an undisturbed environment，po orly aerated and almost
deprived of oxygen. In lagoons，sa linity can become low with influx of仕eshwater，or
become high with evaporation du出19合yseasons. High evaporation has produced血e
deposition of gypsum in several紅easof 百lailand.
In addition to the limestone displaying castellated topographic relief，ot her formations
consist of shale，s iltstone，s andstone and limestone interbeds or lenses，w ith less impressive
topographic features.τbe limestone is commonly not visible in the topography，bu t it may
40 H町RIFo悶 'AINE，SIROT SAL YAPONGSE AND VA RAV UDH S凹宙開O剛
be 'Ofg reat interest in白ese釘chf'Orf 'Ossils. In L'Oei Pr'Ovince，s 'OmeM iddle Carb'Onifer'Ous
limest'One lenses紅'ealgal m'Ounds very rich in algae ass'Ociated with 'Other f'Ossils σONTA町E
ET AL.，in prep紅ati'On).
Ages
The limest'Ones 'OfT hailand bel'Ong t'O different ages. They are pr'Ominent from
Ord'Ovician t'O Middle Jurassic， 'Or企om490 t'O 150 milli'Ony e釘s(Ma) ag'O. During the
Cretace'Ous and the Tertiary (合'Om135 t'O 5M a)，t here was n'O actual sea 'Ont he present land
'OfT hailand and there is n'O marine limest'One 'Oft hese ages. During Late Tertiary and
Quatemary， mむineinfluence sp'Oradically extended t'O l'Ow parts 'Of百lailand，with'Out
imp'Ortant dep'Ositi'On' Ofl imest'One.
In Krabi Pr'Ovince 'OfP eninsular Thailand，c alcare'Ous mudst'One is exp'Osed at Phra
Nang Bay 16 km合'OmKrabi t'Own. It 'Overlies Late Eocene c'Oal beds. Very rich泊 gas位op'Ods，
it is an enchantment f'Ort 'Ourists.τ'heg 部位op'Odsbel'Ong t'O af ew species 'Of合'eshwater
m'Olluses，a cc'Ording t'O identificati'Ons made泊 1949(PπAKPAIVAN ET AL.，19 69).
During the Jurassic (206 t'O 143 Ma)，s ea c'Overed 'Only the westem p紅t'Of百 lailand，
fr'Om Mae H'Ong S'Ont 'O Peninsu1arτ'hailand，w hile the eastem-n'Ortheas旬mpart'Of百凶land，
especially出eKh'Orat Plateau，w 錨 aplain with meandering rivers and r'Oaming din'Osaurs.
Jurassic limest'One is present 'Only in出，ewestem p制'Ofthe c'Oun町.It l'O'Oks fresher白血
the 'Older limest'Ones. It builds up 1紅gehills泊 MaeS'Ota nd Umphang areas. It is l'Ocally
present in Kanch如 ab町iand Mae H'Ong S'On紅'eas.At many l'Ocalities，i t is rich in diverse
f'Ossils; algae，f 'Oraminifera，c 'Orals，b rachi'Op'Ods，g a紺op'Ods，bivalves and amm'Onites have
been n'Oticed and 'Occasi'Onally described.
Triassic (248 t'O 205 Ma) limest'One is presently kn'Own泊 many釘国s'Of百国land，
from the pen加sulat'O n'Orthem and eastem百lailand.Because Triassic limest'One is n'Ot
different合'Omthe Permian limest'One at af irst gl佃 ce，it was儲signedt'O Permian泊血e
past in s'Ome釘eas'Ofc entral，e astem and s'Outhem 百lailand.Because it is rich in diverse
f'Ossils，i t has been p'Ossible t'O ascertain the exact age 'Oft he Triassic limest'One 'Ofs everal
&
areas during recent pale'Ont'Ol'Ogical research σONTA町E VACHARD，1 981; FONTA町EET
AL.，1 993; AMPORNMAHA，1 995; FONTAINEET AL.，20 01 and 2003). In the Lamp gBasin
如
'Ofn 'Orthem 官lailand，出eTriassic sequences紅'em'Ore血佃 3000m thick and have been
kn'Own f'Ora l 'Ong time (PITAKPAIVAN，1 955).百 eyc'Ontain significant carb'Onate facies 'Of
different lith'Ol'Ogic types. Thel imest'One approximately c'Orresp'Onds t'O af 'Ourth 'Oft he t'O凶
secti'On. Its fauna (bivalves，b rachi'Op'Ods，a nd amm'Onites) has been described. It bel'Ongs
t'O L'Ower (Upper Griesbachian 'Ort he l'Ower part 'Ofth e L'Ower Triassic)，M iddle (L'Ower and
Upper Anisian) and Upper (Middle Carnian) Triassic (CHONGLAKMANI，1 981;
CHONGLAKMANI & OUDOMUGSORN，u npublished rep'Ort: 14 pふ
Permian limest'One (290 t'O 247 Ma) is very widespread all 'Over the c'Oun町，evenafter
the c'Orrecti'On'O ft he ages 'Ofs 'Omel imest'One 'Outcr'Ops e汀one'Ouslyassigned t'O出e“Permian
Ratburi Limest'One"泊出，epast.百lePermian limest'One mainly bel'Ongs t'O L'Ower and
Middle Permian. Upper Permian limest'One is rare and d'Oes n'Otb uild thick f'Ormati'Ons; it
is kn'Own at af ew l'Ocalities泊 Lampangand Nan泊 N'Orth官lailand，泊血eKlaeng釘'ea
泊 EastThailand，a nd fr'Om Phangnga佃 daf ew 'Other l'Ocalities ('Only l'Ower pぽt'OfUpper
Permian) in Peninsular 百 ailand.百leUpper Permian limest'One is n'Otd iverse in f'Ossils;
it釘m'Ounces白egreatm部 sextincti'On' Oft he end 'Of血ePermian. It is ass'Ociated with shale
FOSSIL BIODIVERSITY IN THE LIMESTONES OF THAILAND 41
Table 1. Divisions of the Mesozoic. Times are the beginning of the periods in Ma.
Tertiary 65Ma
Cretaceous Upper 99Ma
Lower 144Ma
Tithonian 151Ma
Upper = Malm Kimmeridgian 154Ma
Oxfordian 159Ma
Callovian 164Ma
Bathonian 169Ma
Jurassic Middle = Dogger B吋ocian 176Ma
Aalenian 180Ma
Toarcian 190Ma
Pliensbachian 195Ma
Lower = Liassic Sinemurian 202Ma
Hettangian 206Ma
Upper Norian 221Ma
C nian 227Ma
倒
Triassic 恥I{iddle Ladinian 234Ma
Anisian 242民I{a
Lower Olenekian 245Ma
lnduan 248勘1a
containing peculiar brachiopods，th e Lyttoniidae. Lower and Middle Permian limestones
are commonly very rich in diverse fossils with prominent assemblages of fusulinaceans
and corals. TheL ower Permian，k nown for al ong time at Khao Tham N nMaholan in
創
Loei Province，e xtends south to the Nam Piyang Din Waterfall eaaccording to new
釘
findings (FONTA町EETA L.， 2002; new data).
Carboniferous (354 to 289 Ma) and Devonian (417 to 355 Ma) limestones are rein
訂
Peninsular and West Thailand. ln Loei region in Northeast Thailand，t hey are widely
exposed at many localities (FONTAINE ETA L. in preparation).
Carboniferous limestones are less widespread than the Permian limestones. They are
in evidence in Eastem Thailand (Klaeng，Sa Kaeo and Kabinburi areas)，in Central Thailand
(Ban Bo Nam area east of Lam Narai，N oen Maprang and Chon Daen areas west and
southwest of Petchabun)，泊 Northeastem官lailand(at many localities of Loei Province)，
in Northwestem Thailand (between Mae Hong Son and Chiang Dao as well as north of
Chiang Dao)，in Westem Thailand (northwest of Kanchanaburi) and in the southem part
of Peninsular Thailand. Fusulinella has been very recently discovered in al imestone lens
included in shale near Nam Piyang Din Waterfall (new data). Accordingly，th is new locality
(17003'21 "N，10 1 044'45"E) belongs to an age corresponding to upper Middle Carboniferous;
the Carboniferous was previously unknown in that area. In Thailand，L ower Carboniferous
is known at ag reater number of localities than Middle and Upper Carboniferous. Lower
Carboniferous fossils have been collected from limestone in Peninsular Thailand as early
42 匝到RIFON1・A別E，SIRIσr SALYAPONGSE AND VARAVUDH Suτ'EETHORN
Table 2. Divisions of the Paleozoic
Upper =L opgi Changhsingian 252Ma
泊 佃
Wuchiapingian 256Ma
Midian 259Ma
Middle =G uadalupian Murgabian 262Ma
Permian Kubergandian 264Ma
Kungurian 266Ma
Lower =C isuralian Artinskian 269Ma
S紘marian 282Ma
Asselian 290Ma
Upper =Upper Pennsylvanian Gshelian 296Ma
Kasimovian 303Ma
Middle=Lower Pennsylvanian Moscovian 311Ma
Carboniferous Bashkirian 323Ma
Se甲ukhovian 327Ma
Lower =M ississippian Visean 342Ma
Tournaisian 354Ma
Upper Famennian 364Ma
Frasnian 370Ma
Devorian Middle Givetian 380Ma
Eifelian 391Ma
Emsian 400Ma
Lower Pragian 412Ma
Lochkovian 417Ma
Pridoli 419Ma
Siluri Ludlow 423Ma
組
Wenlock 428Ma
Llandovery 443Ma
Ashgill 449Ma
Caradoc 458Ma
Llandeilo 464Ma
Ordovician Llanvirn 470Ma
Arenig 485Ma
Tremadoc 490Ma
Upper
Cambrian Middle
Lower 543Ma