U–Pb dating for zircons from granitic rocks in southwestern Cambodia
Etsuo Uchida,
Shinya Nagano,
Sota Niki,
Ko Yonezu,
Takumi Yokokura,
Rathborith Cheng,
Takafumi Hirata
Affiliations
Etsuo Uchida
Department of Resources and Environmental Engineering, School of Creative Science and Engineering, Waseda University, Ohkubo 3-4-1, Shinjuku, Tokyo, 169-8555, Japan; Corresponding author.
Shinya Nagano
Department of Resources and Environmental Engineering, School of Creative Science and Engineering, Waseda University, Ohkubo 3-4-1, Shinjuku, Tokyo, 169-8555, Japan
Sota Niki
Geochemical Research Center, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo, 113-0064, Japan
Ko Yonezu
Department of Resources and Environmental Engineering, School of Creative Science and Engineering, Waseda University, Ohkubo 3-4-1, Shinjuku, Tokyo, 169-8555, Japan
Takumi Yokokura
Department of Resources and Environmental Engineering, School of Creative Science and Engineering, Waseda University, Ohkubo 3-4-1, Shinjuku, Tokyo, 169-8555, Japan
Rathborith Cheng
Department of Geology, Ministry of Mines and Energy, #79-80, St. 51, Sankat Phsar Thmey III, Khan Daun Penh, Phnom Penh, 12210, Cambodia
Takafumi Hirata
Geochemical Research Center, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo, 113-0064, Japan
U–Pb dating was conducted for zircons from a total of 14 samples from 13 granite bodies in southwestern Cambodia using LA-ICP-MS. The granitic rock samples were collected from southwestern Cambodia, southwest of the Mae Ping Fault extending from northwest Cambodia via Tonle Sap Lake to southern Vietnam. The studied rock bodies belong to the ilmenite-series, except for three granitic rock bodies. They were identified as I-or A-type. The analysis yielded three distinct age ranges: 295–309, 191–232, and 75–98 Ma. The 295–309 Ma ages are associated with the Paleo-Tethys Sea subduction beneath the Indochina Block. The ages of 191–232 Ma may correspond to the amalgamation period of the Sibumasu and Indochina Blocks during the Indosinian Orogeny. Granitic rocks with ages of 75–98 Ma occur near the southeastern Cambodia-southern Vietnam border. Formation of these granitic rocks was associated with the Paleo-Pacific Ocean Plate (the Izanagi Plate) subduction beneath the Indochina Block. The region in which these granitic rocks occur is part of the Dalat–Kratie Zone.
