Origin and provenance of Lower Jurassic clastic rocks in the Badaowan Formation, Dachanggou Basin, Northern Xinjiang, China: Constraints on Early Jurassic weathering and depositional processes

The Dachanggou Basin, a small intermontane basin in the southern Central Asian Orogenic Belt (CAOB), preserves high-resolution Early Jurassic clastic records of regional tectonics, orogenic uplift, and paleoclimatic changes. We integrate petrological, geochemical, and detrital zircon U-Pb data from the Badaowan Formation. Geochemical signatures demonstrate minimal alteration by sedimentary recycling, hydraulic sorting, or diagenesis. High Chemical Index of Alteration (CIA) values and sandstone petrography indicate moderate to strong chemical weathering. Geochemical data indicate that the Badaowan Formation was deposited in a post-collisional intracontinental rift basin, with mudstone (including oil shale) detritus primarily sourced from a felsic volcanic arc within a stable continental island arc setting. Sandstone petrology, dominated by felsic volcanic lithics and quartz, supports this interpretation. Detrital zircon ages reveal three dominant populations and minor Proterozoic groups, recording multiple magmatic episodes with limited ancient recycling. The 530–480 Ma zircons derive from Cambrian arcs north of East Junggar and Permian Bogda Mountain sediments. The 430–390 Ma and 360–270 Ma groups correlate with magmatism in the Yemaquan and Bogda arcs. The youngest zircon at 250 Ma suggests that Indosinian orogenesis in East Junggar began no earlier than this time. Provenance shifted from proximal Yemaquan Arc to distal Bogda Arc during the Early Jurassic, coinciding with increasingly warmer, more humid climatic conditions. This transition implies tectonic uplift and erosional exhumation of the eastern Bogda Orogenic Belt (BOB) by the late deposition stage of the Badaowan Formation.