拗陷湖盆“古湖岸线”“古深湖线”位置判别方法——以鄂尔多斯盆地上三叠统延长组长6油层组为例

Location discrimination methods of"ancient lake shoreline"and"ancient deep lake line"in continental lacustrine basin:Taking Chang 6 layers of Yanchang Formation in Ordos Basin as an example

确定地质时期古湖岸线和古深湖线的空间位置是拗陷湖盆古地理恢复、沉积演化、沉积相划分的关键和基础,文中以鄂尔多斯盆地晚三叠世延长期长6油层组为例,采用岩心、测井、野外剖面等多种资料,系统分析、判断湖岸线、深湖线位置附近的沉积构造、岩石颜色、旋回、化石等多种典型标志形成机理及识别特征。结果表明,水上、浅水和深水环境在沉积构造、沉积旋回、冲刷面、化石、测井相等多方面存在明显差异,是判定古湖岸线、古深湖线位置的有效方法。该研究成果对拗陷湖盆沉积相划分、砂体分布、湖盆演化等方面的研究提供了依据和参考。

It was the key and foundation of paleogeography,sedimentary evolution and sedimentary facies division to distinguish the spatial location of lake shoreline and deep lake line.Taking Chang 6 oil-bearing formation in Yanchang period of Late Triassic in Ordos Basin as an example,using various data such as core,logging and field profile,this paper systematically analyzes the formation mechanism and identification characteristics of various typical markers such as sedimentary structure,rock color,cycle and fossils near the location of lake shoreline and deep lake line.The results show that there are obvious differences in sedimentary structure,sedimentary cycle,scouring surface,fossils and logging among water,shallow water and deep water environments,which is an effective method to determine the location of ancient lake shoreline and ancient deep lake line.The research results provide a basis and reference for the study of sedimentary facies division,sand body distribution and basin evolution in the depression lake basin.