二○○九年九月 地 球 学 报 Sep. 2009 第三十卷 增刊 1: 40-43 Acta Geoscientica Sinica Vol.30 Supp.1: 40-43 www.cagsbulletin.com www.地球学报.com

Late (Lopingian) foraminifers from the Doi Chiang Dao Limestone in the Inthanon Zone of Northern Thailand

Akira MIYAHIGASHI1,*, Katsumi UENO2, Thasinee CHAROENTITIRAT3 1. Doctoral Program in Earth Science, Graduate School of Science, Fukuoka University, Fukuoka 814-0180 Japan; 2. Department of Earth System Science, Faculty of Science, Fukuoka University, Fukuoka 814-0180 Japan; 3. Department of Geology, Faculty of Science, Chulalongkorn University, Bangkok 1030 Thailand

Abstract: Late Permian foraminifers were found from six localities belonging to the Doi Chiang Dao Limestone, which is considered as having a Paleo-Tethyan seamount-capping carbonates origin, distributed in the Inthanon Zone of Northern Thailand. Among them, three age-diagnostic assemblages are recognized. They are represented by the occurrences of Codonofusiella kwangsiana, Palaeofusulina cf. minima, and P. prisca, and are referable to the , early , and late Changhsingian, respectively. In particular, the discovery of an assemblage characterized by advanced Palaeofusulina (P. pri sca) is significant because it clearly indicates that the deposition of the Doi Chiang Dao Limestone had continued until the very end of the Permian. These three Late Permian assemblages can be compared with those recently reported from the Shifodong Formation of Pa- leo-Tethyan mid-oceanic carbonates in the Changning-Menglian Belt of West Yunnan, Southwest China. Key words: Foraminifers; Late Permian; Doi Chiang Dao Limestone, Inthanon Zone; Northern Thailand

clastic grainstone/packstone, and oncoidal rudstone, 1 Introduction with minor dolomitic levels and is very pure through- Thailand is geotectonically subdivided into three out the succession with no terrigeous intercalation. fundamental domains, from east to west the Indochina Fossils are abundant in the Doi Chiang Dao Block, Sukhothai Zone, and Sibumasu Block, with a Limestone, including foraminifers (mainly fusulines), peculiar belt of rocks related with the Nan Back-arc corals, bryozoans, brachiopods, crinoids, calcareous Basin (Nan Suture Zone) between Indochina and algae, , and others, Previous biostratigraphic Sukhothai (Ueno and Charoentitirat, in press) (Fig. 1). studies on foraminifers (e.g., Hahn and Siebenhüner, In Northern Thailand, the Inthanon Zone is also rec- 1982; Vachard et al., 1992; Fontaine et al., 1993; Ueno ognized as a geotectonically peculiar area in the east- and Igo, 1997; Ueno et al., 2008; Ueno and Charoenti- ern part of the Sibumasu Block, on whichCAGS Paleo- tirat, in press) revealed that the Doi Chiang Dao Tethyan oceanic materials are widely distributed as Limestone ranges from the Visean (Mississip- dismembered tectonic slices. In this zone, two differ- pian/Early ) to the Changhsingian (latest ent kind of pelagic sedimentary rocks are distributed. Permian). Moreover, the Dienerian (Early ) One is bedded chert conventionally referred to as the Neospathodus dieneri fauna was also re- “Fang Chert”, which represents pelagic deep-sea ported from a limestone outcrop possibly belonging to sediments. Radiolarians are fundamental fossils for the the Doi Chiang Dao Limestone (Savage et al., 2006). dating of the Fang Chert and Middle to Of these previous studies, Hahn and Siebenhüner ages have been proposed for it (e.g., (1982) reported Late Permian (Lopingian) foraminifers, Sashida and Igo, 1999). The other is huge and massive but they only listed the species. Therefore, the details carbonates called the Doi Chiang Dao Limestone and of the Late Permian foraminiferal information are yet are considered as having a mid-oceanic seamount- unclear. capping carbonate origin (Ueno et al., 2008). It is as- Recently, we carried out field investigation in the sociated with basalt at the base, to which an oceanic Chiang Dao area, about 100km north of Chiang Mai, intra-plate affinity has been proposed based on geo- Northern Thailand (Fig. 2) and newly found Late Per- chemical analysis (Phajuy et al., 2005). The Doi mian foraminifers from several localities of the Doi Chiang Dao Limestone consists essentially of shal- Chiang Dao Limestone. In this paper, we report them low-marine carbonates, such as ooid grainstone, bio- and discuss their geohistorical implications.

* Corresponding author. E-mail: [email protected]; Tel: +81-(0)90-67669935.

Supp.1 Akira MIYAHIGASHI et al.: Late Permian (Lopingian) foraminifers from the Doi Chiang Dao Limestone in the… 41

Fig. 1 Map showing geotectonic units in Northern Thailand. Modified from Ueno and Charoentitirat (in press).

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Fig. 2 Geologic map around Chiang Dao, with indications of sampling localities.

Wuchiapingian foraminifers were found from 2 Late Permian foraminiferal assemblages three localities, of which two are along the western During the course of this study, we collected margin of Doi Pha Daeng (CPR-7 and 11; Fig. 2) and samples from a total of 78 localities belonging to the the remaining one is at the south of Ban Huai Luek Doi Chiang Dao Limestone (Fig. 2). Six of them (CPR-27; Fig. 2). This assemblage includes Codono- yielded Late Permian foraminifers. Based on their ages, fusiella kwangsiana, Reichelina changhsingensis, three foraminiferal assemblages (Wuchiapingian, early Neoendothyra, Dagmarita, Pachyphloia, and others. Changhsingian, and late Chaghsingian ones) were Of them, C. kwangsiana is well-known as an indicator recognized. of the Wuchiapingian of South China (Sheng, 1963; 42 Acta Geoscientica Sinica Vol.30

Rui, 1979). Absence of both Midian fusulines such as sissippian/Early Carboniferous) to the Changhsingian Neoschwagerina and Yabeina and Changhsingian Pa- (Lopingian/Late Permian) without any large deposi- laeofusulina in this assemblage is consistent with this tional gap (Ueno et al., 2008). age assessment. In the Doi Chiang Dao Limestone of the Inthanon At the northern flank of Doi Chiang Dao, two lo- Zone, we recognized three foraminiferal assemblages calities (DLC-13 and 15; Fig. 2) yielded early in its Lopingian part. They can be rightly referable to Changhsingian foraminifers. This assemblage is not the three foraminiferal zones established on shelf areas very diversified taxonomically but includes Palaeo- of the South China Block (Sheng, 1963; Rui, 1979). fusulina cf. minima, Reichelina changhsingensis, Moreover, Ueno and Tsutsumi (2009) recently reported Pachyphloia, Robuloides and others. Palaeofusulina abundant Lopingian foraminifers from the Shifodong minima is one of primitive palaeofusulinids and gener- Formation of the Changning-Menglian Belt, West ally indicates an early Changhsingian age (Rui, 1979). Yunnan, Southwest China. This formation is consid- Late Changhsingian foraminifers were discovered ered as constituting the uppermost part of Paleo- from one locality at the north of Ban Huai Luek Tethyan seamount-type carbonates in that belt. The (CPR-35; Fig. 2). This assemblage includes many fo- taxonomic compositions of the Shifodong foraminif- raminiferal species and genera such as Palaeofusulina eral assemblages have close affinities to those of the prisca, Nankinella, Staffella, Climacammina, Dag- Doi Chiang Dao Limestone. However, our early marita, Hemigordius discoides, Midiella, Agatham- Changhsingian assemblage clearly shows lower diver- mina, Kamurana?, Postendothyra, Neoendothyra, Ro- sity than the coeval one from the Shifodong Formation. buloides, Lingulina, Pachyphloia, Nodosaria, Pseu- In contrast, late Changhsingian assemblages from the dotristix, Globivalvulina, Paraglobivalvulina, and both have high taxonomic diversity. As already sug- others. In this locality, Staffella, Nankinella, and Cli- gested by Ueno and Tsutsumi (2009), Paleo-Tethyan macammina are particularly abundant in number. It is seamount-type carbonates presumably provided a pe- important to note the presence of advanced Palaeo- culiar habitat suitable for shallow-marine foraminifers fusulina, P. p r is c a . Rui (1979) concluded that a large, in a pelagic paleoequatorial condition by the end of the advanced type of Palaeofusulina generally indicates a Permian. late Changhsingian age in South China. In South China, Rui (1979) established three Acknowledgments: We thank Dr. Apsorn Sardsud, Ms. fusuline zones in the Late Permian, in ascending order, Sujitta Pananto and Ms. Hatairat Boonlue (Department the Codonofusiella Zone (Wuchiapingian), Palaeo- of Mineral Resources, Thailand) for their support in fusulina minima-Nankinella guizhouensis Zone (early the field. Changhsingian), and P. sinensis Zone (late Changh- References: singian). The foraminiferal assemblage from the Doi Chiang Dao Limestone can be compared with those Fontaine H, Suteethorn V, Vachard D, 1993. Carboniferous and from these foraminiferal zones in South China, re- Permian limestone in Sop Pong area: Unexpected lithology spectively. CAGSand fossil. In: Thanasuhtipitak T, (ed.), Proceedings of the In- 3 Discussion ternational Symposium on Biostratigraphy of Mainland Southeast Asia, Chiang Mai, 31 January-5 February 1993: Fa- In the Doi Chiang Dao Limestone, Late Permian cies & Paleontology, 2, 319-336. foraminiferal information was rather poorly presented Hahn L, Siebenhüner M, 1982. Explanatory Notes (Paleontology) in previous studies; only a small foraminiferal assem- on the Geological Maps of Northern and Western Thailand blage consisting of Climacammina lagenalis and Pa- 1:250,000 (Sheets Nan, Chiang Rai, Phayao, Chiang Dao, laeofusulina pseudoprisca (=P. p r is c a ) has been listed Chiang Mai, Li, Thong Pha Phum). Bundesanstalt für Ge- by Hahn and Siebenhüner (1982) from a locality at the owissenscharten und Rohstoffe, Hanover. northern flank of Doi Chiang Dao. This locality is seemingly very close to our DLC-13 and 15 (Fig. 2), Phajuy B, Panjasawatwong Y, Osataporn P, 2005. Preliminary geo- from which the early Changhsingian foraminiferal chemical study of volcanic rocks in Pang Mayao area, Phrao, assemblage was obtained. Chiang Mai, northern Thailand: Tectonic setting of formation. In our study, we found a clearly late Changhsin- Jour. Asian Earth Sci., 24, 765-776. gian foraminiferal assemblage containing advanced Rui L. 1979. Upper Permian fusulinids from western Guizhou. Acta Palaeofusulina (P. p r is c a ), which makes clear that the Palaeont. Sinica, 18, 271-297 (in Chinese with English ab- deposition of the Doi Chiang Dao Limestone had con- stract). tinued at least by the very end of the Permian. Thus, Sashida K, Igo H, 1999. Occurrence and tectonic significance of we conclude, based on this information, that the Doi and Radiolaria in Thailand and Malaysia. Chiang Dao Limestone ranges from the Visean (Mis- In: Metcalfe I. (ed.), Dispersion and Asian Accre- Supp.1 Akira MIYAHIGASHI et al.: Late Permian (Lopingian) foraminifers from the Doi Chiang Dao Limestone in the… 43

tion (IGCP 321 Final Results Volume). A. A. Balkema, Rot- Limestone: Paleo-Tethyan Mid-oceanic carbonates in the In- terdam, Brookfield, 175-196. thanon Zone of North Thailand. In: Choowong M, Thitimakorn Savage N M, Sardsud A, Orchard M, 2006. Conodonts of Dienerian T, eds., Proceedings of International Symposia on Geoscience age () from northern Thailand. In: Lüer V, Hollis Resources and Environments of Asian Terranes (GREAT 2008), C, Campbell H, Simes J, (eds.), Programme & Abstracts, In- 4th IGCP516, and 5th APSEG, Bangkok, 24-26 November 2008, terRad 11 & Triassic Stratigraphy Symposium: A Joint Inter- 42-48. national Conference Hosted by International Association of Ueno K, Igo H, 1997. Late Paleozoic Foraminifers from the Chiang Radiolarian Paleontologists, IGCP467 and the Subcommission Dao area, Norrthern Thailand: Geologic age, faunal affinity, of Triassic Stratigraphy, Wellington, 19-24 March 2006, 120. and paleobiogeographic implications. Prace Panst. Inst. Geol., Sheng J C, 1965. Permian Fusulinids of Kwangsi, Kueichow and 157, 339-358. Szechuan. Palaeont. Sinica, N. S. B, 10, 1-247 (in Chinese and Ueno K, Tsutsumi S, 2009. Lopingian (Late Permian) foraminiferal English). faunal succession of a Paleo-Tethyan mid-oceanic carbonate Ueno K, Charoentitirat T, Chapter 5 Carboniferous and Permian. In: buildup: The Shifodong Formation in the Changning-Menglian Ridd M F, Barber A T, Crow M J, eds., The Geology of Thai- Belt, West Yunnan, Southwest China. Island Arc, 18, 69-93. land. Geological Society, London (in press). Vachard D, Fontaine H, Caridroit M, 1992. Foraminifera, algae and Ueno K, Charoentitirat T, Sera Y, Miyahigashi A, Suwanprasert J, pseudo-algae from Carboniferous and Permian limestone of Sardsud A, Boonlue H, Pananto S, 2008. The Doi Chiang Dao North-west Thailand. Rev. Paléobiol., 11, 137-147.

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