Research articles NAT. NAT. HIST. BUL L. SIAM Soc. 55(2): 199 ・221 ，2∞7 CARBONIFEROUS CORALS OF PANG MAPHA DISTRICT ， NORTHWEST THAILAND Henri Fontain eI and 拘 ravudh Suteethorn 2 ABSTRACT Abundant Abundant Carboniferous corals have been described in Central ηlailand (N oen Mapr 加 g to to Chon Daen area west of Phetchabun) and Northe ぉ tTh ailand (Loei and Nong Bua L 創 nphu 針。'vinces) (FONT Al NE EF AL. ，1991). 百 ey were previously unknown in Northwest Th ailand where where limestone exposures were ∞mmonly assigned to the Permian. Since then ，Carbonifer- ous ous fossils have been discovered at many limestone localities of Northwest Th ailand and corals corals have been collected mainly in Pang Mapha District (Dis 凶 ct established in 1997 with b 柏町is 岡山 n offices built ne 釘 Sop Pong Village). In fact ，Carboniferous limesto l) e is widespread 泊 Northwest Thailand and spans the whole Carboniferous (Fo 悶"A I阻 EF AL. ， 1993). New and more detailed information on the corals is given in this paper. Corals Corals are common in the Lower Carboniferous limestones of Northwest Th ailand. 百ley consist consist mainly of Tabulata (Syringopora is widespread) and diverse solitary Rugosa (Ar ach- nolasma ， Kueichouphyllum and others). Compound Rugosa locally occur and aI官 sporadicall y in in abundance. They consist of fascicula 飽 corals (Solenodendron ，D 伊'hyphyllum); massive Rugosa Rugosa have not been encountered up to now. At some localities ， the corals are fragments accumulated accumulated by water currents. Elsewhe 陀，白ey are better preserved. Middle Carboniferous limestone containing so Ji tary Rugosa (Caninophyllum ， Bothrophyllum 飢 d others) occurs at a few localities of Northwest Th ailand. Tabulata 紅官 very rare rare and consist of massive corals (Chaetetes) 釦 d fasciculate corals (Multithecopora). A small number of Upper Carboniferous limestone exposures have been studied. Corals are are extr 芭mely rare in these places. Key words: Karst topography ，Limestone ，Rugosa ，Tabulata ，Moscovian ，Visean- Serpukhovian Serpukhovian STUDY AREA Fossil Fossil hunters get landscape shock when they 紅 rive in 出edis 凶 ct ofPang Mapha in Mae Hong Son Pr ovince (Fig. 1). Li mestone exposures 釘 e very widespread. Karstic topography with castellated hills and deep sinkholes does not help the geological research ，but it provides wonderfullandscapes (Figs. 2 and 3) ，an immediate enchantment even during a first 凶 p in the the region (FONTA 別 E ET AL. ， 1987). In addition ，caves are common and many a町 act tour- ists; ists; they 釘 e loc a1 1y followed by underground rivers. Many caves have been investigated by archaeologists ，especi a1 1y during the last 10 years. In the distant past ，they were signi 自cant places of human activity ，temporary or permanent habitation sites ，and occasion a1 1y burial I 8 allee de la Chapelle ，92140 Clamart ， France Geological 2 Geological Survey ， Department of Mineral Resources ，Rama IV Road ，Bangkok 10400 ，τ 'h ailand. Received Received 10 September 2006; accepted 10 June 2007 199 200 HENRIFo 附'A INE AND V ARAVUDH SUTEETHORN sites. sites. Th ey contain tools ，pottery ， bones and rock paintings. This prehistoric material includes stone stone tools as old as 12 ，500 ye 紅 s in the lowest levels. In the more recent layers ， iron tools have been found.τREERAYAPIWAT (2005) gives information on excavations carried out at a rock rock shelter ne 紅 Ban Huai Rai ， a village along the Lang River 3.5 km west of Pang Mapha. Other Other localities of the Pang Mapha District have been studied ， for instance Tham Lod (unpublished (unpublished reports of Silpakorn University). In addition to the wonderful prehistoric remains ， limestone hills and caves are “important biodiversity hotspots" (SRIKOSAMATARA ET AL. ，2004). People living in Am phoe Pang Mapha 紅 ea belong to several 住ibes;theyincrease the the interesting diversity of this region. Southwest Southwest of Am phoe Pang Mapha or Ban Sop Pong ，limestone ， hundreds of meters thick ， forms a plateau oscillating between 1，000 佃 d1 ，300 m in elevation above sea level ， extending extending over at least 130 km2• The topography is characterized by the absence of valley and surface drainage ， but by the presence of many dolines (sinkholes). Few people live in the area. area. Streams appe 紅 around the area ，st 紅 ting at elevations ranging from 600 to 950 m. Susa Waterfall ，9 km south of Ban Mae Suya ，is an important underground s仕'eam coming out at the the foot of a limestone cliff and falling into Kh ong Ri ver. In other areas north and northwest of of Pang Mapha ，rivers appe 肌 but shortly disappear into holes or seep slowly into the soi l. Many su 甲山es await the visitor. In In 1970 ， the general understanding of the geology of northern Thailand was: “The Carboniferous Carboniferous is in its lower p紅 tdistinct flysch facies ， followed by a mainly basic volcanic section. section. The Upper Carboniferous is represented by locally te 町 estrial deposits and overlap- ping ping reef-limestone" (BAUM ET AL. ， 1970). Th e limestone was assigned mainly to Permian. 百le recent paleontological results in 出 e district of Pang Mapha show that limestone also represents represents the Lower ，Middle and Upper Carboniferous (FONTAlNE ET AL. 1993 ，2005 ， and unpublished unpublished data). DESCRIPTION OF THE CORALS During the Carboniferous ， marine shallow water environments with diverse faunas characterized characterized the Am phoe Pang Mapha area. Green algae were common. Corals flourished when conditions were good ， for instance with clean and well aerated water. Some corals had a simple horn-shaped form (solitary Rugosa); other corals were compound and branching (fasciculate (fasciculate Rugosa and most of the Tabulata). Massive corals appe 訂 to be very rare in 出e PangMapha 紅白. Solitary Solitary Rugosa Solitary Solitary corals are commonly scattered and in a small number ， with a diameter of 2 cm at at the maximum. Very locally ，出 ey are in abundance or display larger diameters. They 紅 'enot always always very well preserved; because of that ，it is difficult to identify all the species occuring in in the Pang Mapha area. LOPHOPHYLLIDAE Grabau ， 1928 Some fragments of very simple solitary corals without dissepiments have been found west west of Ban Pha Phueak (1 90 38' 59.7"N ，98 0 12' 15 .3 "E; samples T9546 and T9547). CARBONIFEROUS CORALS OF PANG MAPHA DISTR ICT. NORTHWEST THAILA D 20 ] MYANMAR (Shan States) .·· .. .... · .. .• • •• • •. .. ••• · . • Ban ·... ·. ! • Pang ••••• . Khong •. ; • Ban Pung .. • Yam •. : . • Ban. Dol Khu • ···. ..... • • • • • •. Ban Pang • . Kham • • • •• · ....... •. Ban Pang• Tong •. • • Ban Pha Phueak •• Ban Ph a Daeng ...... Ban Sale • \ • • Ban Pang Kham Noi I Ban Nam Phu Pha Suea • • Ban Mae Lana • Ban Huai Sal Khao Ban Chabu Tham Lod • 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 Di stri ct area . 202 H EN RI FONTA INE AND V ARAVUDI-I SUTEETI-IORN Figure 2. Limestone hills south o f Ban Pha Phueak. Figure 3. Photograph towards the east from a shale outcrop halfway between Ban C habu and Ban Mae Lana. The shale has yielded Lower Pennsylva nian ammo no ids at a locality to the no rth. The photograph shows the Early Carbonife rous li mestone hill near Ban Mae La na. West of the shale outcrop outside of the photograph, Moscovian limestone bu ilds up hill s near Ban Chabu ; it is locall y rich 111 Fusul inidae. CARBONlFEROUS CORALS OF PANG MAPHA DISTRICT ，NORTHWEST THAILAND 203 They reach only 1 cm in diameter at the maximum. Septa 紅 'e of two orders. The counter septum is long and thickened in 出e axial part of the cora l. The cardinal septum is shorter than the the other major septa. These corals are in a packstone containing calcispheres ，r訂 e algae ，and locally locally abundant Fusulinidae. They belong to Moscovian as the Bothrophyllidae described in in the following lines. Lophophyllidae are common in the Permian limestones of Thailand. In In the Carboniferous limestones ， they were known only at Phu Ki Kai in Northeast Thailand where a limestone has been considered Moscovian in age (FONTAINE ET AL. ，1991 ， 2005). Sample T9514 ，collected south of Ban NamHu Pha Suea ，contains a poorly preserved solitary solitary coral only 9 mm in diameter. Septa are of two orders ，28+28 in number. Counter septum is connected to a thick median plate. This coral possibly belongs to Lophophyllidae. It It does not display dissepiments. CYATHOPSIDAE Dybowski ， 1873 Two small fragments of transverse thin sections obtained from a sample (T9371) collected collected north of Ban Mae Lana show lonsdaleoid dissepiments and appear to belong to Siphonophyllia Siphonophyllia Scouler ， 1844. The occuη'ence of this genus was so far known in Thailand only 企om poor material collected from a single locality (Pha Chom Nang) in Northeast Thailand Thailand (FONTAI 阻 ETAL. ， 1991). Caninia Caninia Michelin ， 1840 Caninia ， another genus of the Cyathopsidae ， is well known in the Carboniferous of Northeast Northeast and Central Thailand. A few specimens have been noticed in Northwest Thailand. Thailand. Caninia Caninia cf. lipoensis (Chi ，193 1) 1991-cf. Caninia 1伊oensis (Chi) ，Fo 悶'A INE ET AL.， p. 32-33 ， p l. 1 ，figs. 5-7; pl. 5 ，fig. 7 Studied Studied materia l. -Sample T9550 collected west ofBan Pha Phueak (1 90 38' 59.7"N ， 98 0 12' 15.3"E; fig. 4). Description.-Small solitary coral ，5 mm in diameter ，known by a single transverse section. section. Septa are of two orders ，18+ 18 in number. Major septa are not very long and do not occupy the axial part of the cora l.