西苏门答腊实武牙地区晚三叠世花岗岩锆石年代学及其特提斯构造意义

苏门答腊岛位于东特提斯构造域,沿该岛分布了大量不同时代和成因的花岗岩,但这些花岗岩的形成时代和延伸以及对比均未能得到很好的界定,也限制了对东南亚主要岩浆岩带延伸及其构造背景的理解.对西苏门答腊实武牙地区新识别出的花岗岩体开展了精细的LA-ICP-MS锆石U-Pb年代学研究.结果显示,3个花岗岩样品的锆石均为典型的岩浆成...

Zircon U-Pb Geochronology of Late Triassic Granites from Sibolga Area in Western Sumatra and Its Tethyan Tectonic Implications

The Sumatra Island, located in the Tethyan tectonic domain, preserves abundant granitoids with various ages and petrogenesis. The paucity of precise geochronological data for these granitoids has hampered our understanding on the extension and tectonic setting of magmatic belts in Southeast Asia. Precise zircon U-Pb geochronological data for granites from the Sibolga area in western Sumatra are presented in this study. Our results suggest that zircon grains from these samples are of igneous origin. LA-ICP-MS zircon U-Pb dating yields crystallization ages of 215.1±2.4 Ma (MSWD=0.14), 206.1±5 Ma (MSWD=0.22) and 214.3±5 Ma (MSWD=0.11) for granites respectively, indicating the Late Triassic magmatism in western Sumatra. Comparing with those of contemporary igneous rocks in Southeast Asia, it proposes that the Late Triassic granites in the Sibolga area are consistent with the West Province granite. Therefore, these granites might be formed in a back-arc rift setting in response to the initial subduction of the Mesotethyan Ocean during the Late Triassic.