石臼坨凸起西南陡坡带扇三角洲锆石定年与源汇示踪

为了示踪渤海湾盆地石臼坨凸起西南陡坡带扇三角洲源汇体系，对其东三段层序（Ed₃）的6个砂岩样品进行碎屑锆石U-Pb定年分析.西部扇体（C6-4-4井）富含白垩纪（K）锆石并具有110 Ma峰值，母岩以白垩系义县组火成岩为主；中部（C6-4-3、C6-4-6D井）、东部扇体（C6-4-5D）富含侏罗纪（J）锆石并具有152 Ma或168 Ma峰值，母岩以侏罗系蓝旗组火成岩为主，古生代（Pz）锆石则来自中生界碎屑岩.所有样品都含有太古代（Ar）、元古代（Pt）锆石，母岩为花岗岩基底.研究表明，除古生界碳酸盐岩外，源区的母岩地层均可通过碎屑锆石U-Pb年龄示踪，各扇体物源的差异性是由母岩地层倾向控制的，由于中生界向西北倾斜，白垩系主控西部扇体沉积，侏罗系则是中部、东部扇体的主要物源区. 

Detrital Zircon U-Pb Geochronology and Provenance Tracing of the Fan Deltas along the Southwestern Slope of the Shijiutuo Uplift

To trace sedimentary Source-to-Sink systems of the southwestern Shijiutuo uplift, Bohai bay basin, 6 sandstone cuttings from 3 fan deltas of the third member of Dongying Formation (Ed₃), along the southwestern slope of Shijiutuo uplift, were systematically sampled for detrital zircon U-Pb dating analysis in this study. It is found that sediments of the western fan delta (C6-4-4) were characterized with abundant Cretaceous zircons and a notable peak at 110 Ma, controlled by volcanic rocks of Cretaceous Yixian Formation. The sediments of the middle fan delta (C6-4-3, C6-4-6D) and the eastern fan delta (C6-4-5D) were characterized by high percentage of Jurassic zircons and a 152 Ma or 168 Ma peak, dominated by volcanic rocks of Jurassic Lanqi Formation, while their Paleozoic zircons derived from the Mesozoic sedimentary rocks. Moreover, all the samples received Archean-Proterozoic zircons from the exposed basement. This study shows that all the source strata can be traced by detrital zircon U-Pb dating except for the Paleozoic carbonate. The diversity of the provenances of the fan deltas was controlled by the inclination of the source strata:as the Mesozoic strata inclined to northwest, the Cretaceous strata dominated the western fan delta while the Jurassic strata controlled the middle and eastern fan deltas.