吴峰,任培罡,谈明轩,等. 东海西湖凹陷孔雀亭地区平湖组沉积相演变及其主控因素分析[J]. 海洋地质与第四纪地质,2022,42(2): 119-130. doi: 10.16562/j.cnki.0256-1492.2021052401
引用本文: 吴峰,任培罡,谈明轩,等. 东海西湖凹陷孔雀亭地区平湖组沉积相演变及其主控因素分析[J]. 海洋地质与第四纪地质,2022,42(2): 119-130. doi: 10.16562/j.cnki.0256-1492.2021052401
WU Feng,REN Peigang,TAN Mingxuan,et al. Facies evolution and its controlling factors of the Pinghu Formation in the Kongqueting area of Xihu Depression, the East China Sea[J]. Marine Geology & Quaternary Geology,2022,42(2):119-130. doi: 10.16562/j.cnki.0256-1492.2021052401
Citation: WU Feng,REN Peigang,TAN Mingxuan,et al. Facies evolution and its controlling factors of the Pinghu Formation in the Kongqueting area of Xihu Depression, the East China Sea[J]. Marine Geology & Quaternary Geology,2022,42(2):119-130. doi: 10.16562/j.cnki.0256-1492.2021052401

东海西湖凹陷孔雀亭地区平湖组沉积相演变及其主控因素分析

Facies evolution and its controlling factors of the Pinghu Formation in the Kongqueting area of Xihu Depression, the East China Sea

  • 摘要: 东海陆架盆地西湖凹陷含有巨量的石油天然气资源,具有极佳的勘探潜力,其中平湖组沉积作为重要的含油气层,已成为近期油气勘探的聚焦点。孔雀亭地区为西湖凹陷研究程度较低的区块,对于该区域沉积相及其控制因素方面的研究仍然较少。基于钻井资料与三维地震资料对孔雀亭平湖组沉积微相进行精细刻画,并系统分析了全球海平面、区域构造、古气候、古地貌对研究区沉积微相演变的控制作用。研究表明,平湖组下段(包括平下下段、平下上段)以潮坪沉积为主,辫状河三角洲沉积只发育在源区附近,而平中段与平上段以辫状河三角洲沉积为主,潮坪沉积分布面积迅速降低。由平下段至平中段,随着相对海平面(全球海平面与区域构造综合效应)下降,辫状河三角洲向海方向发生进积。同时,平中段与平上段时期极高的CO2浓度使得大陆源区剥蚀量快速增加,大量沉积物随着河流输入至西湖凹陷,从而进一步加剧了辫状河三角洲的向海推进。平下段与平中段早期的古地貌断陷发育较多,对辫状河三角洲的扩张存在限制作用,而经历了平中段大量沉积物充填之后,早期的洼陷逐渐被填平,从而平上段的辫状河三角洲可以大范围地向海方向发生推进,形成规模庞大的三角洲砂体沉积。

     

    Abstract: The East China Sea Shelf Basin contains a huge amount of petroleum resources and the Pinghu Formation is one of the major exploration targets. However, the Kongqueting area has rarely been researched, and few studies have been made to sedimentary facies evolution and its controlling factors. Based on drilling and 3D seismic data, microfacies of the Pinghu Formation are carefully described in this paper and the controls of global sea level fluctuation, regional tectonics, paleoclimate, and paleogeography over the facies distribution patterns discussed. The Lower Pinghu Formation is dominated by tidal flat facies, and the braided river delta facies only appeared in some places near uplifts. By contrast, the Middle and Upper Pinghu Formations are dominated by deltaic deposits of braided rivers. Relative sea level falling, as a joint result of global sea level change and regional tectonics, resulted in the progradation of braided river delta towards offshore. Meanwhile, the high concentration of CO2 in the atmosphere during the Middle and Later Pinghu periods caused a sharp increase of erosion. Enormous sediments provided by the source areas were transported into the Xihu Depression, which accelerated the progradation of braided river delta into the sea. In addition, the paleogeographic framework during the Middle to Lower Pinghu Periods were characterized by many fault-controlled sags, which limited the expansion of braided river delta. These sags were filled by sediments in Middle Pinghu Period, and turned to tidal flat in Later Pinghu Period, which also helped the expansion of deltaic deposits of the Upper Pinghu Formation.

     

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