断陷盆地海陆过渡相烃源岩发育模式:以西湖凹陷平湖组为例

始新统平湖组是东海盆地西湖富生烃凹陷的主力烃源岩系，也是中国东部断陷盆地海陆过渡相烃源岩的典型代表.利用钻井、地震及烃源岩有机地球化学、古生物等资料，在烃源岩特征及其发育的构造-沉积与古气候背景分析的基础上，探讨了平湖组烃源岩发育的主控因素，并建立了相应的形成模式.平湖组暗色泥岩分布广、厚度大，夹多套薄煤层及碳质泥岩，总体烃源岩质量较高.平湖组烃源岩发育于半封闭的海湾环境和温暖-潮湿南亚热带型气候条件，以陆生有机质输入为主.平湖组烃源岩的发育主要受沉积-沉降速率、母质来源及有机质保存条件等因素控制，其形成模式可概括为"快速沉降；气候温暖-潮湿；陆生有机质输入为主；淡水-半咸水；氧化性较强的环境". 

Development Model for Source Rock of Marine-Continental Transitional Face in Faulted Basins: A Case Study of Pinghu Formation in Xihu Sag

Source rock in Pinghu Formation of Eocene is the main source rock series in Xihu hydrocarbon generating sag of the East China Sea shelf basin, and it is also a typical source rock of marine-continental transitional face in the faulted basins of East China.Using drilling, seismic data combined with organic geochemistry and paleontology data of hydrocarbon source rock, the development controlling factors for the Pinghu Formation are discussed and the forming model is established by analyses of characteristics of the hydrocarbon source rock and tectonic-sedimentary-palaeoclimate development background in this study.It is found that source rocks in Pinghu Formation of Xihu Sag are characterized by wide distribution, large thickness and multiple series of thin coal seam with carbonaceous mudstone, relatively high quality of source rocks.The development background of Pinghu Formation is a semi-enclosed bay environment with warm-humid subtropical climate condition, and predominantly terrestrial organic matter contribution.The development of hydrocarbon source rocks in Pinghu Formation is mainly affected by sedimentation-subsidence rate, source material and preservation condition of organic matter, forming model could be concluded with "rapid subsidence, warm-humid climate, terrestrial organic matter, fresh-brackish water, and relatively strong oxidation condition".