渤海东北部辽东凸起锦州27构造沙河街组碎屑锆石物源示踪

    Source tracing of detrital zircons from Shahejie Formation of the Jinzhou 27 Structure in Liaodong Uplift, northeastern Bohai Sea

    • 摘要: 渤海东北部辽东凸起锦州27构造沙河街组砂体发育情况横向变化快,开展物源示踪对于明确砂体分布具有重要意义。通过对研究区砂岩的锆石U-Pb年龄、锆石形态和岩屑成分分析,明确研究区沙河街组母岩时代、类型及主要物源区。结果表明:①沙河街组主要发育峰值年龄为120 Ma的白垩纪锆石和峰值年龄为1 800、2 500 Ma的古元古代锆石。白垩纪锆石多呈柱状,发育棱角,具有生长环带,古元古代锆石多呈浑圆状,棱角不明显,生长环带多发生破坏。②沙四段沉积时期,砂岩中古元古代锆石占比为55%,白垩纪锆石占比为25%,岩屑类型以变质岩为主。沙三段—沙一二段沉积时期,砂岩中古元古代锆石占比为44%,白垩纪锆石占比为33%,岩屑类型以火山岩、变质岩为主。③沙河街组母岩以胶辽隆起复州北部地区新元古界沉积岩为主,同时受辽东凸起不断隆升影响,盆地内白垩系火山岩物源的影响逐渐增加。

       

      Abstract: Development of sand bodies in the Shahejie Formation (SF) in the Jinzhou 27 Structure of the Liaodong Uplift in the northeast of Bohai Sea showed rapid lateral changes, thus conducting source tracing is of great significance for clarifying the distribution of sand bodies. By analyzing the zircon U-Pb age, zircon morphology, and debris composition of the sandstone in the study area, the age, type, and source area of the parent rock of the SF in the study area were clarified. Results indicate that: ① The SF mainly develops Cretaceous zircons with peak ages of 120 Ma and Paleoproterozoic zircons with peak ages of 1800 Ma and 2500 Ma. Zircons from the Cretaceous period are mostly columnar in angular shape with growth rings. The Paleoproterozoic zircons are mostly round in shape, with indistinct edges and corners, and their growth rings are often damaged. ② In the fourth member of SF, the proportion of Paleoproterozoic zircons in sandstone was 55%, and that of Cretaceous zircons was 25%. The rock fragments were mainly from metamorphic rocks. From the third to first and second members of SF sediments, the proportion of Paleoproterozoic zircons in sandstone was 44%, and that of Cretaceous zircons was 33%. The rock fragments were mainly from volcanic rocks and metamorphic rocks. ③ The parent rock of SF is mainly composed of Neoproterozoic sedimentary rocks in the northern part of Fuzhou in the Jiaoliao Uplift. At the same time, influenced by the continuously uplift of Liaodong Uplift, the influence of the provenance of Cretaceous volcanic rocks in the basin area gradually increased.

       

    /

    返回文章
    返回