Abstract:
The tectonic framework in Hala-alate Mountain area of Xinjiang at the Late Carboniferous is island arc developed under trench-arc-basin system, and the Upper Carboniferous Tailegula Formation black shale is considered to be a product of deep-water deposition in the trench and forearc basin during the period of island arc effect being relatively weakened, but with a lack of geochemical evidence. Trench exploration and sampling analysis were conducted on the black shales of Tailegula Formation in the study area. The results show that the black shale of Tailegula Formation in the study area is rich in MgO and Na
2O, poor in TiO
2, Al
2O
3, Fe
2O
3 and CaO
2, and moderate in SiO
2. The large ion lithophile element is relatively poor, and light rare earth element is relatively rich. The heavy rare earth element is relatively loss, and the
δEu has negative anomaly, indicating similar distribution pattern with rare earth element in the upper crust. The tectonic setting of Tailegula Formation black shale in Hala-alate Mountain is mainly the continental island arc. The source rock belongs to intermediate to acid and felsic provenance, and it mainly originates from upper continental crust. The source region is probably Early Paleozoic trench-arc of Tarbagatay-Narmande and Late Paleozoic island arc of Xiemisitai-Dongquan in the north. This study could provide some references for the provenance analysis of the giant thick shales in Hala-alate Mountain area.