Missing ophiolitic rocks along the Mae Yuam Fault as the Gondwana–Tethys divide in north-west Thailand |
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Authors: | Ken-ichiro Hisada Masaaki Sugiyama Katsumi Ueno Punya Charusiri Shoji Arai |
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Institution: | Institute of Geoscience, University of Tsukuba, Tsukuba 305-8571, Japan (email: ),; Technology and Environment Department, Petroleum Association of Japan, Tokyo 100-0004, Japan,; Department of Earth System Science, Fukuoka University, Fukuoka 814-0180, Japan,; Department of Geology, Chulalongkorn University, Bangkok 10330, Thailand and; Department of Earth Sciences, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan |
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Abstract: | Abstract Thailand comprises two continental blocks: Sibumasu and Indochina. The clastic rocks of the Triassic Mae Sariang Group are distributed in the Mae Hong Son–Mae Sariang area, north‐west Thailand, which corresponds to the central part of Sibumasu. The clastic rocks yield abundant detrital chromian spinels, indicating a source of ultramafic/mafic rocks. The chemistry of the detrital chromian spinels suggests that they were derived from three different rock types: ocean‐floor peridotite, chromitite and intraplate basalt, and that ophiolitic rocks were exposed in the area, where there are no outcrops of them at present. Exposition of an ophiolitic complex denotes a suture zone or other tectonic boundary. The discovery of chromian spinels suggests that the Gondwana–Tethys divide is located along the Mae Yuam Fault zone. Both paleontological and tectonic aspects support this conclusion. |
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Keywords: | detrital chromian spinel mafic rock Sibumasu suture zone ultramafic rock |
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