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Research articles ∞ NAT. HIST. BULL. SIAM Soc. 55(2): 199・221，2 7 ， CARBONIFEROUS CORALS OFP ANG MAPHAD ISTRICT NORTHWEST THAILAND Henri FontaineI and 拘ravudhSuteethorn2 ABSTRACT Abundant Carboniferous corals have been described in Central ηlailand (Noen Mapr加g to Chon Daen area west of Phetchabun) and NortheぉtThailand (Loei and Nong Bua L創nphu 針。'vinces)(FONTAlNE EF AL.，1 991).百eywere previously unknown in Northwest Thailand where limestone exposures were ∞mmonly assigned to the Permian. Since then，Ca rbonifer- ous fossils have been discovered at many limestone localities of Northwest Thailand and corals have been collected mainly in Pang Mapha District (Dis凶ctestablished in 1997 with b 柏町is岡山noffices built ne釘 SopPong Village). In fact，C arboniferous limestol)ei s widespread泊NorthwestThailand and spans the whole Carboniferous (Fo悶"AI阻 EFAL.，19 93). New and more detailed information on the corals is given in this paper. Corals are common in the Lower Carboniferous limestones of Northwest Thailand.百ley consist mainly of Tabulata (Syringopora is widespread) and diverse solitary Rugosa (Arach- nolasma，Ku eichouphyllum and others). Compound Rugosa locally occur and aI官sporadically in abundance. They consist of fascicula飽 corals(Solenodendron，D 伊'hyphyllum);massive Rugosa have not been encountered up to now. At some localities，th e corals are fragments accumulated by water currents. Elsewhe陀，白eyare better preserved. Middle Carboniferous limestone containing soJitary Rugosa (Caninophyllum， Bothrophyllum飢dothers) occurs at af ew localities of Northwest Thailand. Tabulata紅官very rare and consist of massive corals (Chaetetes)釦dfasciculate corals (Multithecopora). As mall number of Upper Carboniferous limestone exposures have been studied. Corals are extrmelyrare in these places. 芭 Key words: Karst topography，L imestone，R ugosa，T abulata，M oscovian，V isean- Serpukhovian STUDY AREA Fossil hunters get landscape shock when they紅rivein出edis凶ctofPang Maphai n Mae Hong Son Province (Fig. 1). Limestone exposures釘every widespread. Karstic topography with castellated hills and deep sinkholes does not help the geological research，bu t it provides wonderfullandscapes (Figs. 2a nd 3)，a n immediate enchantment even during af irst凶pin the region (FONTA別EETA L.，1 987). In addition，ca ves are common and many a町acttour- ists; they釘eloca11y followed by underground rivers. Manyc aves have been investigated by archaeologists，es pecia11y during the last 10 years. In the distant past，th ey were signi自cant places of human activity，te mporary or permanent habitation sites，a nd occasiona11y burial I 8a llee de la Chapelle，92 140 Clamart，Fr ance 2 Geological Survey，De partment of Mineral Resources，R ama IV Road，Ba ngkok 10400，τ'hailand. Received 10 September 2006; accepted 10 June 2007 199 200 HENRIFo附'AINEAND VA RAVUDH SUTEETHORN sites. They contain tools，po ttery，bo nes and rock paintings. This prehistoric material includes stone tools as old as 12，500 yesin the lowest levels. In the more recent layers，ir on tools 紅 have been found.τREERAYAPIWAT (2005) gives information on excavations carried out at a rock shelter ne BanHuai Rai，a v illage along the Lang River 3.5 kmw est of Pang Mapha. 紅 Other localities of the Pang Mapha District have been studied，fo r instance Tham Lod (unpublished reports of Silpakorn University). In addition to the wonderful prehistoric remains，li mestone hills and caves are“important biodiversity hotspots" (SRIKOSAMATARA ETA L.，20 04). People living in Amphoe Pang Mapha紅eabelong to several住ibes;theyincrease the interesting diversity of this region. Southwest of Amphoe Pang Mapha or Ban Sop Pong，li mestone，hu ndreds of meters thick，fo rms ap lateau oscillating between 1，000 d1，300 m in elevation above sea level，佃 extending over at least 130 km2• The topography is characterized by the absence of valley and surface drainage，bu t by the presence of many dolines (sinkholes). Few people live in the area. Streams appe aroundthe area，st tingat elevations ranging from 600 to 950 m. Susa 紅紅 Waterfall，9 k ms outh of Ban Mae Suya，is an important underground s仕'eamcoming out at the foot of al imestone cliff and falling into Khong River. In other areas north and northwest of Pang Mapha，ri vers appe肌 butshortly disappear into holes or seep slowly into the soil. Many su甲山esawait the visitor. In 1970，th e general understanding of the geology of northern Thailand was:“The Carboniferous is in its lower ptdistinct flysch facies，fo llowed by am ainly basic volcanic 紅 section. The Upper Carboniferous is represented by locally teestrialdeposits and overlap- 町 ping reef-limestone" (BAUM ETA L.，19 70). Thel imestone was assigned mainly to Permian. 百lerecent paleontological results in出edistrict of Pang Mapha show that limestone also represents the Lower，Mi ddle and Upper Carboniferous (FONTAlNE ETA L. 1993，2005，an d unpublished data). DESCRIPTION OFT HE CORALS During the Carboniferous，m arine shallow water environments with diverse faunas characterized the Amphoe Pang Mapha area. Green algae were common. Corals flourished when conditions were good，fo r instance with clean and well aerated water. Some corals had as imple horn-shaped form (solitary Rugosa); other corals were compound and branching (fasciculate Rugosa and most of the Tabulata). Massive corals appe訂 tobe very rare in出e PangMapha 紅白. Solitary Rugosa Solitary corals are commonly scattered and in as mall number，w ith ad iameter of 2c m at the maximum. Very locally，出eyare in abundance or display larger diameters. They紅'enot always very well preserved; because of that，it is difficult to identify all the species occuring in the Pang Mapha area. LOPHOPHYLLIDAE Grabau，1 928 Some fragments of very simple solitary corals without dissepiments have been found west of Ban Pha Phueak (190 38' 59.7"N，9 80 12' 15.3"E; samples T9546 and T9547). CARBONIFEROUS CORALS OF PANG MAPHA DISTRICT. NORTHWEST THAILA D 20] MYANMAR (Shan.. .S tates) .·· .. . ·.. . .. • •• •• • .· . .. .. • ••· . · . • • Ban .! • Pang ••••• .. . Khong • .. . . ; • Ban Pung • : • Yam ···. .. ... •• Ban Dol Khu • • • • • •. •. • Ban Pang • Kham• • • ·. ...... . • • •.. Ban P•an g Tong ...... • • • Ban Pha Phueak •• • Ban Ph a Daeng Ban Sale • \ I Ban Nam Phu • Ban Pang Kham Noi Pha Suea • • Ban Mae Lana Ban Chabu Tham Lod • • Ban Huai Sal Khao Ban Mai Sang Nam • • Ban Huai Phung Ban Huai Rai Ban Nam Bo Sape • to Pai and Chiang Mai • Ban Huai Ban Luk Pa Ko • Pa Tueng Ban Mae Yan • Pang Mapha area 0 4km Figure I. Pang Mapha District area. 202 HENRI FONTAINE AND VARAVUDI-I SUTEETI-IORN Figure 2. Limestone hills south of Ban Pha Phueak. Figure 3. Photograph towards the east from a shale outcrop halfway between Ban Chabu and Ban Mae Lana. The shale has yielded Lower Pennsylvanian ammonoids at a locality to the north. The photograph shows the Early Carboniferous limestone hill near Ban Mae Lana. West of the shale outcrop outside of the photograph, Moscovian limestone builds up hills near Ban Chabu; it is locally rich 111 Fusul inidae. CARBONlFEROUS CORALS OF PANG MAPHA DISTRICT，N ORTHWEST THAILAND 203 They reach only 1c m in diameter at the maximum. Septa 'eof two orders. The counter 紅 septum is long and thickened in出eaxial part of the coral. The cardinals eptum is shorter than the other major septa. These corals are in ap ackstone containing calcispheres，r ealgae，an d 訂 locally abundant Fusulinidae. They belong to Moscovian as the Bothrophyllidae described in the following lines. Lophophyllidae are common in the Permian limestones of Thailand. In the Carboniferous limestones，th ey were known only at Phu Ki Kai in Northeast Thailand where al imestone has been considered Moscovian in age (FONTAINE ETA L.，19 91，2005). Sample T9514，co llected south of Ban NamH u Pha Suea，co ntains ap oorly preserved solitary coral only 9m mi n diameter. Septa are of two orders，2 8+28 in number. Counter septum is connected to at hick median plate. This coral possibly belongs to Lophophyllidae. It does not display dissepiments. CYATHOPSIDAE Dybowski，1 873 Two small fragments of transverse thin sections obtained from as ample (T9371) collected north of Ban Mae Lana show lonsdaleoid dissepiments and appear to belong to Siphonophyllia Scouler，1 844. The occuη'ence of this genus was so far known in Thailand only企ompoor material collected from as ingle locality (Pha Chom Nang) in Northeast Thailand (FONTAI阻 ETAL.，1991). Caninia Michelin，1 840 Caninia，a nother genus of the Cyathopsidae，is well known in the Carboniferous of Northeast and Central Thailand. A few specimens have been noticed in Northwest Thailand. Caninia cf. lipoensis (Chi，1 931) 1991-cf. Caninia 1伊oensis(Chi)，F o悶'AINEETA L.， p. 32-33，p l. 1，fi gs. 5-7; pl. 5，fi g. 7 Studied material.-Sample T9550 collected west ofBan Pha Phueak (19038' 59.7"N， 980 12' 15.3"E; fig. 4). Description.-Small solitary coral，5 m mi n diameter，k nown by as ingle transverse section. Septa are of two orders，1 8+ 18 in number. Major septa are not very long and do not occupy the axial part of the coral. They are slightly thicker in the cardinal quadrants. Cardinal septum is al ittle shorter than the other major septa. Minor septa are very short. Tabulae e 紅 f1at in the axial p tof the cora .lDissepiments have commonly been destroyed by the erosion 紅 of the coral periphery; they are rangedin 1o r 2r ows. 紅一 Age. Moscovian.Caninia lipoensis is as pecies described in the Moscovian of China. In Northeast Thailand，it has been found near Ban Pha Noi (FONTAINE ETA L.，1 991). 一 Associated fossils. Caniniacf.lipoensis is associated in sample T9550 with calcispheres， smaller foraminifers，a bundant Fusulinidae (including Neos，t.a酔llasubquadrata Grozdilova & Lebedeva)，fr agments of Mutithecopora and of crinoids. 204 HENRI FONTAINE AND VA RAVUDH SUTEETHORN BOTHROPHYLLIDAE Fomichev，1 953 Bothrophyllidae have been found in limestone largely exposed between Ban Pha Phueak and Ban Pha Daeng. They appear to be widespread，b ut are poorly preserved，s lightly to moderately crushed or in pieces. They are associated with diverse other fossils: Tubiphytes， calcispheres，sm aller foraminifers，Fu sulinidae (in abundance in samples T9549 to T9551)， other corals (Lophophyllidae，C haetetes，a nd fragments of tubes probably belonging to Multithecoporα)，b rachiopods and crinoids. The limestone is wackestone to packstone and belongs to the民10scovian. Bothrophyllidae were previously known only in Northeast Thailand by twog enera: Cani- nophyllum found in aM oscovian limestone exposed along Huai NamS uai，an d Bothrophyllum collected in Ban Pha Noi area (FONTAINE ETA L.，1 991). Caninophyllum Lewis，1 929 Studied material.-Sample T9337 collected in 2005 from as malllimestone hill west of Ban Pha Phueak (Fig. 5). Description.-Solitary coral，pa rtly crushed，3 c mi n diameter.1t is known by only one oblique section. Septa are of two orders，54 +54 in number. Major septa are thickened in the tabularium，mo re intensely in the cardinal quadrants. They display ab lack median line. Cardinal septum is short. Minor septa eshort and thin; they are confined to the dissepimentarium. 紅 Tabulae are flat in the axial part of the coral，12 in av ertical distance of 1c m. Dissepiments are arranged in at least 7r ows. Age.-Moscovian (upper part of Middle Carboniferous). In the thin section studied above，Ca ninophyllum is associated with Fusulinidae belonging to Neos，t.a酔llasubquadrata (Grozdilova & Lebedeva，19 50). Additional material.-Sample T9551 collected in 2006 from the same area as the coral described in the preceding lines，al ong ar oad from Ban Pha Phueak to Ban Pha Daeng (19038' 59.7"N，98 0 12' 15.3"E)，is only af ragment; it seems to belong also to Caninophyl- lum. Bothrophyllum Trautschold，1 879 Studied material. -Sample T9338 collected west of Ban Pha Phueak. See Fig. 6. Description. -Solitary coral，2. 5 cmi n diameter，kn own by 2t ransverse sections; slightly crushed. It belongs probably to Bothrophyllum Trautschold，1 879. Septa are of two orders， at least 45+45 in number. Major septa are long and extend almost to the axis of the coral. They are thickened in the tabularium; they display ab lack median line. They are thin in the dissepimentarium. The thickened part of the cardinal septum is short，bu t is prolonged by a thin lamina. Minor septa are short. Dissepiments are aangedin about 4r ows. The wall of 町 the coral is thin and partly destroyed. Age.-Moscovian. Sample T9338 contains Fusulinidae belonging to Fusulinella and Aljutovella while sample T9337 from the same locality contains Neostaffella subquadrata Grozdilova & Lebedeva. CARBONIFEROUS CORALS OF PANG MAPI-IA DISTRICT. NORTH仇IESTTI-IAILAND 205 Figure4 . SalllpleT 9550:C aninia cf. lipoensis in al illlestone( packstone) rich in Fusuliniclae. 、 Figure5 . SampleT 9337 (Cω1inophyllum) isn OIp erfectly preserv巴cl.1Ii sa ssociatecl Nithotherc orals‘ comlllonly with Ihes allle type0 '1preservaiton0 1' evenI llorep oorly preservecl 206 HENRIF ONTAINE AND VARAVUDH SUTEETHORN Figllres 6.S ample T9338: Bothrophyllurn.T his sample was associated in the field with sampleT 9337 (Caninopllyllurn.) Figllres 7.S al11ples T9544 alld T9540: BOlhrophyllu川 collectedwesto f Ban Pha Phllealく Sal11pl巴 T9544， transvers巴andlongitlldinal sections; sal11pl巴T9540，transverse sectioll. CARsONIFEROUS CORALS OF PANG MAPHA DISTRICT，N ORTHWEST THAILAND 207 Figlll巴8.SampleT 9347: Neocli日ophylllllllfrom san Pha Phlleak area Figllres 9.S ampleT 9512:A rachno!asllla sinense( transverse and longitllIcinals ections).S ampleT 2775 might belong 10 Arachllo!as川0ιy!illdricLlIII(transverse section) 208 HENRI FONTAINE AND VA RAVUDH SUTEETHORN Additional materiat -Samples T9540，T9 544 and T9549 have been collected from the same area as T9338，al ong ar oad from Ban Pha Phueak to Ban Pha Daeng (190 38' 59.7"N， 980 12' 15.3"E; Fig. 7). Solitary corals are common in this place. Alittle farther alongthe same road (190 39' 22.0"N，98 0 12' 13.2"E)，co rals are scattered in the limestone (samples T9559 and T9560). All these corals are more or less crushed and not easy to study. They are about 2c mi n diameter in their upper part. Septa are of two orders，u p to 36+36 in number. They are similar to those of sample T9338. In av ertical section (sample T9544; Fig. 7)，ta bulae are 16 in av ertical distance of 1c m. They are almost flat; they are commonly incomplete. Dissepiments are arranged in 4t o 6r ows. AULOPHYLLIDAE Hill，1 981 Aulophyllidae are the most common and diverse solitary Rugosa of the Amphoe Pang Mapha area，wh ere they belong to the upper part of the Lower Carboniferous. They are diverse. They are also abundant at some Lower Carboniferous localities of Central and Northeast Thailand from where specimens of Arachnolasma，Ku eichouphyllum and 拘anophyllumhave been collected (FONTAINE ETA L.， 1991). Kueichouphyllum Yu，1 931 is al arge solitary coral，be longing mainly to Upper Visean. It is already known in Northeast，Ce ntral and East Thailand (sumrnary of the discoveries in FONTAINE ETA L.，20 05). It is in abundance in some limestone beds of Central Thailand. In central Laos，it is common at Ban Phit and Ban NaH i east ofThakkek (FONTA町E，1961). In Northwest Thailand，Ku eichouphyllum does not appear to be widely distributed. At Km 9.4 ofthe road along Khong River north ofBan Mai Sang Nam，a s ingle sample ofthis genus has been observed in the field; it was 5c mi n diameter. CLISIOPHYLLINAE Nicholson，1 889 Few samples of Clisiophyllinae have been collected. Only as ingle sample is described in the following lines. Neoclisiophyllum Wu 1964 Studied material.-Sample T9347 collected near and west of Ban Pha Phueak (Fig. 8). Description.-Sample T9347 was looking like ab eautiful solitary coral at the surface of the rock. It was only af ragment and it has been possible to obtain only at ransverse section，co espondingto am ature growth stage. The coral is presently 1.4 cmi n diameter，bu t 汀 is strongly eroded at its periphery. Its original size was larger. M負jorsepta are 42 in number and extend almost to the axial structure. They are thickened in the tabularium and display a clear microstructure. Counter septum is thinner than the other major septa and moderately long，ex tending towards an angular elongation of the" axial structure. Cardinal sepωmis shorter than counter septum. Minor septa are thin，sh ort and rarely visible because of the erosion of the coral periphery. Dissepiments are aηanged in more than two rows. The axial structure is well defined by ab ounding wall. It is 4m min diameter. It is densely constructed by axial tabellae and moderately by septallamellae. It has at hick median plate. Tabulae are entirely unknown because of the lack of al ongitudinal section.