[Objective]The Xihu Depression,located in eastern China,is a significant area for oil and gas explo-ration.While previous studies have focused on deep strata,such as the Pinghu Formation,little research has been conducted on the middle and shallow strata,including the Huagang Formation.Recent findings suggest that these shallow and middle strata have hydrocarbon accumulation potential,but their hydrocarbon-generating capacity and the source of crude oil in the Xihu Depression remain uncertain.[Methods]To address these gaps,we collected 203 source rock samples from 13 drilling boreholes in the western slope zone and central inversion tectonic zone of the Xihu Depression.These samples spanned from the Eocene Baoshi Formation to the Miocene Longjing Forma-tion.Geochemical tests and analysis were conducted to assess the hydrocarbon potential and biomarker characteris-tics of the source rocks.[Results]The results indicate that coal and carbonaceous mudstone in the Xihu Depres-sion have excellent hydrocarbon generation potential,while the hydrocarbon generation potential of mudstone va-ries.Deep layer source rocks are evaluated as good or excellent sources of hydrocarbons,while the middle and shallow layers are considered poor sources.The organic matter in the source rocks mainly consists of types Ⅱ2-Ⅲ,and the thermal evolution stage can be divided into a hydrocarbon generation stage(Ro＞0.6％)and a large hydro-carbon expulsion stage(R＞0.8％).Comparing the biomarkers of crude oil and different types of source rocks,we found that the argillaceous source rock in the study area is the primary source of crude oil.[Conclusion]This re-search provides valuable guidance for future oil and gas exploration in the Xihu Depression.
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