CEOSEA '98 Proceedin/J J, CeoL. Soc. JJ1aLaYJia BuLL. 45, Decemuer 1999,. pp. 467-475 Ninth Regional Congress on Geology, Mineral and GEOSEA '98 Energy Resources of Southeast Asia - GEOSEA '98 17 - 19 August 1998 • Shangri-La Hotel, Kuala Lumpur, Malaysia Middle Carboniferous cephalopods from Loei area, northern Thailand MASAYUKI FUJlKAWAI, TAKESHI ISHIBASHI1 AND NIKORN NAKORNSRI2 1 Department ·of Earth and Planetary Sciences, Faculty of Science Kyushu University Fukuoka 812-8581, Japan 2Geological Survey Division, Department of Mineral Resources (DMR) Rama VI Rd ., Bangkok 10400 Thailand Abstract: The Carboniferous cephalopods are abundantly recognized at "Barite Mine", northern part of Loei-city, northern Thailand. The fauna of "Barite Mine" consists of various taxa such as cephalopods, brachiopods, corals, bivalves and gastropods etc. More than three hundreds specimens of cephalopods consisting of ammonoids, nautiloids and orthoceratids are collected and are replaced by barite minerals. Five genera of ammonoids and five genera of nautiloids are identified at present. In addition to these, one new genus and two new species of ammonoid are included. The identified cephalopod species are as follows; Branneroceras branneri, Diaboloceras inuolutum, Syngastrioceras sp., Neogastrioceras sp., Bisatoceras sp., Catastroboceras subsulcatifomae, Epidomatoce ras doohylense, Gzheloceras sp, Temnocheilus sp., and Epistroboceras sp. These cephalopod fauna indicates the age from Namurian to Moscovian of the Middle Carboniferous. This fauna is very important to construct the biostratigraphy based upon the Paleozoic ammonoid zones in Southeast Asia. INTRODUCTION several districts of Thailand (Pitakpaivan et al., 1969; Glenister et al., 1990; Ishibashi and The present paper deals with the Carboniferous Chonglakmani, 1990; Ishibashi et al., 1994, 1996, cephalopods collected from north of Loei-city, 1997) (Fig. 2). These ammonoids coexist occasionally Changwat Loei, north Thailand (Fig. 1). with fusulinids, smaller foraminifers, bryozoans, The standard biostratigraphy of Carboniferous and brachiopods. and Permian have been constructed on the basis of The ammonoid fossils are very useful to fusulinaceans in Thailand (Pitakpaivan, 1965; correlate one region with others, and to determine Baum et al., 1970; Igo, 1972; Toriyama et al., 1975; the geological age of carbonate and non-calcareous Ingavat et al., 1980; Ingavat, 1984; Toriyama, 1984). sediments. Therefore the paleontological study of Meanwhile, the Carboniferous and Permian Paleozoic ammonoids is very important. The ammonoids have been rarely reported from purpose of this paper is to report some new Southeast Asia as well as Thailand and the Carbonifeous cephalopods and to construct the biostratigraphy depends on Paleozoic ammonoid biostratigraphy of Carboniferous and Permian on has never been proposed until now. They have the basis of ammonoid fossils. been sporadically reported from the restricted regions of Southeast Asia (e.g., Timor and Thailand). OUTLINE OF GEOLOGY IN LOEI AREA In Thailand, Reed (1920), Ingavat-Helmcke, (1994) and Ishibashi et al. (1997) have only reported the The Paleozoic deposits are distributed in several occurrence of Carboniferous ammonoids including districts of Thailand, except the western part, questionable species, but none of them have been named as the Khorat Plateau (Fig. 2). The described. The Indonesian Timor is the only known Carboniferous and Permian systems are classified occurrence of Carboniferous ammonoids in in some stratigraphic belts (Kobayashi, 1964; Southeast Asia (Haniel, 1915). On the other hand, Bunopas, 1994) and are distributed along these the Permian ammonoids have been reported from belts from north to south in Loei area. 468 MASAYUKI FUJIKAWA, TAKESHllsHIBASHI AND NIKORN NAKORNSRI o{? IS to Chi ang Khan <> Q ~ ~ ~ -~ Barite Mine Thai I and , r~- "-...... t', \.-' :-.. , .~ . , .J \ .. -, 1 .. <~ , " I I • , . , ---' -." ~~ Loei "'" .. I \ \ . Bangkok\ I ,. ..l 900 300 m Figure 1. Index map showing the surveyed region in North Thailand. GEOSEA '98 Proceedin.9J (GSM BuLL. 43) MIDDLE CARBONIFEROUS CEPHALOPODS FROM LOEI AREA, NORTHERN THAILAND 469 N Pronorites sp. (Ingavat, 1994) Branneroceras Protocanites sp. Fauna (Ishibashi et aI., 1997) 7 species of Ammonoid 5 species of Nautiloid Agathiceras aff. suessi !Propinacoceras sp. (Pitakpaivan et al., 1969) Paratirolites nakornsri Pseudogastrioceras aff. szchuanense Agathiceras aff. suessi Xenodiscus ? sp. Properrinites boesei Propinacoceras sp. (Ishi bas hi and Popanoceras sp. Chonglakmani, 1990) Artinskia Loeiensis Tapashanites yaowal{1kae (Ishibashi et al., 1996) (Ishibashi et al., 1994) Miklukhoceras cf. pamiricum Agathiceras mediterraneum Perrinites cf. hilli Prostacheoceras cf. oshense (Glenister et al., 1990) Ammonoid localities Prolecanites (?) sp. • Permian Glyphyoceras (?) sp. o Carboniferous Pronorites aff. cyclolobus ! Formations (Reed, 1920) D Permian D Carboniferous o 200 '--_'------I, km F igure 2. Carboniferous and Permian ammonoid localities in Thailand. December 1.9.9.9 470 MASAYUKI FUJIKAWA, TAKESHllsHIBASHI AND NIKORN NAKORNSRI Table 1. Paleozoic stratigraphy of northeastern Thailand of Jacobson et al. (1969) with some modification. Age Rock Unit Character Phu Khadung Formation Sandstone, siltstone and conglomerate Nam Phong Formation (including basal conglomerate) Triassic unnamed Andesite, rhyolite, tuff, agglomerate unnamed Granodiorite and other intrusive rocks .;:: Permian ::J Massive limestone with shale and .0 Ratburi Limestone cu II) sandstone c:cu·;:: Q) .cQ) goo Sandstone, siltstone, shale, tuff and unnamed Carboniferous cu limestone ~ Sandstone, quartzite, phylitic shale, unnamed Devonian slate and limestone ... Argillite, quartzite, slate, phyllite, Silurian unnamed and older schist A great deal of effort has been made on Carboniferous age for strata in the hills just east of paleontological study in Loei area by many Loei [Kobayashi (Ed.), 1964] and the Devonian age paleontologists. Paleontological studies in Loei area at the Mekong River (Saurin, 1963). are as follows; Igo (1972) reported the Carboniferous The "Barite Mine" is situated at the top of a fusulinaceans collected from the Wang Saphung­ hill, northern part of Loei-city. The lower part of Loei area of Thailand for the first time. Igo et al. the hill is mainly composed of shale, tuff beds (1993) and Toriyama (1982) have also reported the subordinated with dolomite of the Devonian and occurrence of the Permian fusulinacean fossils. with the presence of some brachiopods and trilobites. Kobayashi and Sakagami (1989a) reported Silurian The lower Carboniferous cephalopods occur in the trilobite associated with corals, brachiopods, etc. barite bodies and residue deposits in fissures which from Ban Nang near Loei. They also described weathered from limestone and impure barite. All Carboniferous trilobites from Loei-Ban Sup area in fossils are replaced by barite minerals (BaS04). the same year (Kobayashi and Sakagami, 1989b). Not only trilobites but also many kinds of fossils PALEOZOIC CEPHALOPODS IN such as brachiopods, bryozoans, corals, ammonoids, THAILAND gastropods, etc. were found in this area. The Middle Carboniferous brachiopods were described from Ban The Paleozoic cephalopods have been reported Sup (Yanagida, 1974). The Permian trilobites were from restricted regions not only in Thailand but in described at Tham N am Maholam, Loei district Southeast Asia. The Carboniferous cephalopods (Kobayashi and Hamada, 1979; Kobayashi and are particularly few. The Carboniferous Sakagami, 1989c) with Asselian brachiopods cephalopods have only been reported from three (Yanagida, 1967) and fusulinids (lgo, 1972). localities in Thailand. There are few reports discussing the geology of Reed (1920) has reported Prolecanites(?) sp., Loei area until now. The authors mentioned many Glyphyoceras(?) sp. and Pronorites aff. cyclolobus previous studies, as mentioned above, however, (Phillips) from Hat Yai area, southern part of there were no description about geological setting Thailand. Ingavat (1994) has reported Pronorites around Loei at all. Jacobson et al. (1969) proposed sp. and Ishibashi et al. (1997) has reported the geological data in northern part of Loei-city, Protocanites sp. from Ban Mae Lana near Mae and prepared the geological map and the Hong Song, northwest Thailand. Ishibashi et al. stratigraphic chart (Table 1) around Loei-city. The (1997) have reported four species of ammonoids as paleontological evidences indicate an early follows; Branneroceras sp., Syngastrioceras sp., CEOSEA '98 ProceedingJ (CSM Bull. 43) MIDDLE CARBONIFEROUS CEPHALOPODS FROM LOEI AREA, NORTHERN THAILAND 471 Plate 1. 1. Diaboloceras involutum Nassichuk (a: lateral view, b: ventral view) x 1.0 2-8. Branneroceras branneri (Smith) (a: lateral view, b: ventral view) x 1.0 9 & 10. Syngastrioceras sp. (a: lateral view, b: ventral view) x 1.0 Decell1ber 1999 472 MASAYUKI FUJIKAWA, TAKESHllsHIBASHI AND NI KORN NAKORNSRI Plate 2. 1 & 2. Neogastrioceras sp. (a: lateral view, b : ventral view) x 1.5 3 &4. Bisatoceras sp. (a: lateral view, b: ventral view) x 2.0 5 & 6. Epidomatoceras doohylense (Foard) (a: lateral view, b: ventral view) x 1.0 7 & 8. Catastroboceras subsulcatifomae Shimansky (a: lateral view, b: ventral view) x 1.0 9. Epistroboceras sp. (a: lateral view, b: ventral view) x 1.5 10 & 11. Gzheloceras sp. (a: lateral view, b: ventral view) x 1.0 12. Temnocheilus sp. (a: lateral view, b: ventral view) x 0.75 GEOSEr! '98 ProceerJillfl</