南堡凹陷南部物源古近系沙一段沉积特征

通过沉积构造、岩石类型、粒度、测井特征等分析,认为南堡凹陷南部物源古近系沙一段主要发育辫状河三角洲前缘沉积,主要沉积微相类型为水下分流河道、水下分流河道侧缘、水下分流间湾、河口坝,并局部发育深水滑塌浊积扇、滨浅湖滩坝微相以及滨浅湖沉积。其中:水下分流河道砂体在平面上多呈条带状、片状分布;河口坝及滨浅湖滩坝在平面上主要呈椭圆状、土豆状或不规则状分布在水下分流河道的末端;水下分流河道侧缘在河道主体边侧呈条带状、席状分布;深水滑塌浊积扇主要呈不规则状分布在边界处或者河道砂体之外,整体呈现出辫状河三角洲前缘与滨浅湖的沉积组合,其物源来自南西方向。断裂、古地貌及物源供给方式是影响南堡凹陷南部物源沉积相发育及分布的重要因素。

Sedimentary characteristics of southern provenance of Paleogene Sha 1 Member in Nanpu Sag

By analyzing mudstone color,sedimentary structures,rock types and well logging facies,it reveals that the southern provenance of the Paleogene Sha 1 Member in Nanpu Sag is dominated by braided delta front deposits.Its major sedimentary microfacies are underwater distributary channel,its flank,underwater inter distributary bay and river mouth bars.There are deep water slumped turbidite fans microfacies,loch beach barrier microfacies and shallow lacustrine deposits in some areas.The underwater distributary channel sand bodies have a banding or sheet distribution in the plane.The river mouth bars and loch beach barrier mainly have an elliptical or a potato-like distribution in the plane,or an irregular distribution at the end of the underwater distributary channel.The flank of the underwater distributary channel has a banding or sheet distribution along the channel.The deep-water slumped turbidite has an irregular distribution at the border or out of the border of the channel sand body.Overall its sedimentary assemblage is braided delta front-shallow lacustrine deposits system,and the provenance is from southwest.The fracture,the ancient landform and the supply pattern of the provenance are the key factors that influence the development and distribution of the southern provenance sedimentary facies in Nanpu Sag.