冀中饶阳凹陷西柳10断块古近系沙三段-沙二段层序地层及沉积演化

Sequence stratigraphy and sedimentary evolution of the 3rd and 2nd members of the Palaeogene Shahejie Formation in the Xiliu-10 fault block, Raoyang depression, central Hebei

关键词:  西柳10断块  古近系  沙河街组  层序地层  沉积演化

Key words:  Xiliu-10 fault block  Palaeogene  Shahejie Formation  sequence stratigraphy  sedimentary evolution

摘要:

为了探讨饶阳凹陷蠡县斜坡北东缘西柳10断块古近系沙河街组沙三段-沙二段（Es³-Es²）层序地层特征及其沉积特征，依据高分辨率层序地层学理论，结合岩心、测井等资料，对研究区沙三段-沙二段层序地层进行划分，对其沉积特征、相带展布及其演化规律进行研究。研究结果表明，沙河街组沙三段-沙二段可划分为4个III级旋回，11个IV级旋回，32个V级旋回。沉积物岩性以细砂岩、粉砂岩及泥岩为主，沉积环境主要为辫状河三角洲平原和三角洲前缘，划分出7种沉积微相。结合研究区区域构造演化及沉积背景，认为沙三段-沙二段沉积时期，主要经历湖退到湖进的演变过程。

Abstract:

Sequence stratigraphic division, sedimentary characteristics, and sedimentary facies distribution and evolution are examined in detail on the basis of high-resolution sequence stratigraphic theory, cores and well logs for the 3rd and 2nd members of the Palaeogene Shahejie Formation in the Xiliu-10 fault block, Raoyang depression, central Hebei. The 3rd and 2nd members of the Palaeogene Shahejie Formation may be divided into 4 third-order cycles, 11 fourth-order cycles and 32 fifth-order cycles. Lithologically, the rock types dominantly contain fine-grained sandstone, siltstone and mudstone. The sedimentary environments consist of the braided delta plain and delta front subfacies, which may be subdivided into 7 sedimentary microfacies, including the channel bar, channel filling, overbank, channel margin, subaqueous distributary channel, subaqueous interdistributary bay and channel mouth bar microfacies. Combined with the regional tectonic evolution and sedimentary background, it is believed that the 3rd and 2nd members of the Palaeogene Shahejie Formation mainly experienced the evolutionary processes from the regression to the transgression during their deposition.