Jornal de Geologia e Geofísica
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U-Pb Detrital Zircon Geochronology of Late Triassic to Early Jurassic Sandstones in the Northwestern Junggar Basin and its Implications

Xinchuan Lu1, Xiangyang Xie, Shuncun Zhang, Arthur B Busbey, Shengyin Zhang, Shekuan Du, Guoqiang Sun and Jian Shi

The Junggar Basin is a Late Carboniferous foreland basin in northwestern China surrounded by different mountain belts. The west Junggar Basin has a complicated tectonic history with multiple subduction and collision events that controlled sedimentation and basin development. In this study, absolute dating of igneous rocks, rock geochemistry, and U-Pb detrital zircon geochronology were used to document the provenance of the Triassic-Jurassic clastic rocks in the northwest margin of Junggar Basin and determine local sources and tectonic setting. Granitic zircons with the youngest concordia age reveal the north Karamay pluton was formed at 292.6 ± 0.7 Ma, suggesting that they are postcollision granites. Late Triassic-Lower Early Jurassic strata were derived from Zhayier Mountain south of the Darbute fault. Starting with the Upper Early Jurassic Sangonghe Formation-Lower Middle Jurassic Xishanyao Formation, the strata changed from a single source to mix multiple sources. Sediment sources are widespread, including the northern Karamay granitic plutons, the area north of the Darbute fault, with potentially minor contributions from the southern margin of the Junggar Basin.