Petrochemistry and Tectonic Setting of the Middle Triassic Arc-Like Volcanic Rocks in the Sayabouli Area,NW Laos  

作　　者：Xin Qian Qinglai Feng Yuejun Wang Wenqiang Yang Chongpan Chonglakmani Denchok Monjai 

机构地区：[1]State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430074,China [2]School of Earth Sciences,China University of Geosciences,Wuhan 430074,China [3]School of Earth Science and Geological Engineering,Sun Yat-sen University,Guangzhou 510275,China [4]CAS Center for Excellence in Tibetan Plateau Earth Sciences,Beijing 100101,China [5]Wuhan Center of Geological Survey,Wuhan 430205,China [6]School of Geotechnology,Suranaree University of Technology,Nakhon Ratchasima 30000,Thailand

出　　处：《Journal of Earth Science》2016年第3期365-377,共13页地球科学学刊（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.41172202,41190073,41302178);the China Geological Survey(No.1212011121256);the State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences in Wuhan(No.MSFGPMR201202)

摘　　要：The volcanic rocks from the Sayabouli area in northwestern Laos have been poorly studied. These volcanic rocks are traditionally mapped as the Permian–Early Triassic sequences on the geological map. One basaltic-andesite from the Sayabouli area yields a zircon U-Pb age of 237.7±1.7 Ma, suggesting a Middle Triassic origin. All basalt and basaltic-andesite samples from the Sayabouli area show depletions in HFSEs（e.g., Nb, Ta, Ti） and have high LILE/HFSE ratios, and exhibit the geochemical affinity to the continental arc volcanic rocks and are geochemically similar to the continental arc volcanic rocks from the Phetchabun belt in northeastern Thailand, suggesting a Late Permian–Middle Triassic continental margin in the Sayabouli area of northwestern Laos and Phetchabun area of northeastern Thailand. Our data indicate that the Phetchabun arc volcanic belt through the western Loei sub-belt can be linked to the Sayabouli area in northwestern Laos.The volcanic rocks from the Sayabouli area in northwestern Laos have been poorly studied. These volcanic rocks are traditionally mapped as the Permian–Early Triassic sequences on the geological map. One basaltic-andesite from the Sayabouli area yields a zircon U-Pb age of 237.7±1.7 Ma, suggesting a Middle Triassic origin. All basalt and basaltic-andesite samples from the Sayabouli area show depletions in HFSEs（e.g., Nb, Ta, Ti） and have high LILE/HFSE ratios, and exhibit the geochemical affinity to the continental arc volcanic rocks and are geochemically similar to the continental arc volcanic rocks from the Phetchabun belt in northeastern Thailand, suggesting a Late Permian–Middle Triassic continental margin in the Sayabouli area of northwestern Laos and Phetchabun area of northeastern Thailand. Our data indicate that the Phetchabun arc volcanic belt through the western Loei sub-belt can be linked to the Sayabouli area in northwestern Laos.

关 键 词：volcanic rock geochemical characteristics zircon U-Pb age Middle Triassic Sayabouli northwestern Laos 

分 类 号：P588.14[天文地球—岩石学] P618.130.2[天文地球—地质学]