鄂尔多斯盆地东缘本溪组-太原组层序地层特征

Sequence Stratigraphy of Benxi-Taiyuan Formation in Eastern Ordos Basin

在垂向沉积序列、岩性组合、泥岩样品的地球化学测试、测井响应等综合研究的基础上,在鄂尔多斯盆地东缘本溪组—太原组中识别出区域不整合面、区域构造体制转换面、沉积体制转换面、海侵面等层序界面类型。本溪组—太原组形成于陆表海背景之下,陆表海基底平缓,层序结构大多为二元体系域结构,在构造变动、区域海平面下降及差异性压实作用等因素的控制下形成了以K1砂岩和桥头砂岩为代表的低位体系域河道下切充填。建立了区域层序地层格架以及陆表海背景下的缓坡盆地边缘Ⅰ型层序地层模式和陆表海背景下的缓坡Ⅱ型层序地层模式。

Based on a study of the vertical sedimentary sequence, the assemblage of vertical lithology, geochemical analyses of mudstone samples, and logging characteristics, the authors recognized such sequence stratigraphy interfaces as regional unconformity, regional tectonic regime interface, sedimentary system interface and transgression surface. The Benxi-Taiyuan Formation was formed in an epicontinental sea that had subdued floor, so most of the sequence structures in Benxi-Taiyuan Formation are of dual system character. Tectonic disturbance, sea level change and differential compaction provided enough accommodation space for the distribution of K1 sandstone and Qiaotou sandstone. The framework and model of sequence stratigraphy in Benxi-Taiyuan Formation within eastern Ordos basin are established in this paper, which contains type I model of ramp marginal basin and type H of ramp in an epicontinental sea background.