西湖凹陷平湖斜坡带的物源分析:来自碎屑锆石U-Pb年代学及重矿物的证据

西湖凹陷是东海陆架盆地重要的含油气凹陷，其中平湖组是该凹陷内重要的勘探目的层段。目前平湖组油气发现多集中于凹陷西部斜坡带，由于其他地区钻井资料较少，对于西湖凹陷平湖组砂体展布以及物源区一直存在争议，严重制约了西湖凹陷平湖组的油气勘探。主要通过碎屑锆石U-Pb定年，同时结合重矿物组合特征、重矿物ZTR指数分析和碎屑矿物成分成熟度特征，对平湖组沉积物源区进行追踪，分析结果显示研究区锆石年龄分布相对分散且跨度大，包括中生代、古生代和前寒武纪3个年龄段，且以前寒武纪为主。平湖组主要发育3个物源区，其中北部虎皮礁隆起为主要物源区，西部海礁隆起与东部钓鱼岛隆褶带为次要物源区。对平湖组物源体系的研究为西湖凹陷的油气勘探开发提供借鉴。 

Provenance analysis of the Pinghu slope belt in Xihu Depression: Evidence from detrital zircon U-Pb chronology and heavy minerals

Xihu Depression is an important oil-bearing depression in the East China Sea Basin, in which Pinghu Formation is an important exploration target formation. At present, oil and gas discoveries in Pinghu Formation are mostly concentrated in the western slope zone of Xihu Depression. However, disputes over the sand body distribution and source area of Pinghu Formation in Xihu Depression have been existed for a long time due to the lack of drilling data, which seriously restricts the oil and gas exploration in Pinghu Formation. In this study, the sediment source area of Pinghu Formation was tracked mainly by the detrital zircon U-Pb dating combined with composition characteristic and ZTR index of heavy minerals and the maturity of detrital mineral composition, so as to reveal the development regulation of sand bodies. The age distribution of zircon in the study area is relatively scattered, with a large distribution range, including the Precambrian, Mesozoic and Paleozoic, and the Precambrian is dominant. The analysis results show that three provenances are developed during Pinghu Formation, including the main provenance of the northern Hupijiao Uplift, the western Haijiao Uplift and the eastern Diaoyu Island upwarping folded zone, which can provide important reference for the oil and gas exploration and development in Xihu Depression.