Abstract
The Junggar Basin (NW China) is a polycyclic intracontinental basin formed within the Central Asian Orogenic Belt and characterized by multi-stage tectonic reactivation and composite petroleum systems. This study integrates tectonic evolution, source rock geochemistry, and basin modeling to clarify the spatial–temporal controls on hydro-carbon generation and accumulation. The basin evolved from Late Paleozoic rifting to Carboniferous–Permian collision, followed by Mesozoic thermal subsidence and Ce-nozoic inversion related to the uplift of the Tianshan. Major source rocks include Car-boniferous marine shales (total organic carbon 1.5–5%), Permian lacustrine deposits (up to 10–12% total organic carbon; hydrogen index up to 700 mg HC/g TOC), and Ju-rassic coal-bearing strata. Thermal maturity ranges from 0.6% to >2.0% vitrinite re-flectance, indicating multi-phase oil and gas generation and secondary cracking in deeply buried depocenters. Hydrocarbon accumulation differs across structural zones. Central depressions are dominated by deep gas generation and composite traps, whereas northwestern segments reflect lateral migration from Permian source kitch-ens. Cenozoic inversion significantly reactivated faults and controlled vertical migra-tion pathways. The results highlight that hydrocarbon distribution in the Junggar Ba-sin is governed by the synchronization of tectonic evolution and generation phases, providing predictive insights for exploration in polycyclic inversion basins.