构造对三级层序的控制作用

经典层序地层学理论认为,一级和二级层序受全球性和区域性构造因素控制,全球性海平面变化是三级层序发育的主要因素,构造沉降是线性的、次要的。渤海湾盆地东营凹陷东营三角洲沙三中亚段层序始于42Ma,历经1.5Myr。沙三中亚段层序发育在东营凹陷古近纪构造运动幕,无论是构造沉降速率还是断层生长指数都是最大的,该幕是构造作用最强烈时期,构造作用是决定沙三中亚段层序的主要因素,它改变了地层格架样式,而湖平面变化、沉积物的供给只是改变了沙三中亚段三角洲前积层的形态和大小。

TECTONIC CONTROLS ON THIRD-ORDER SEQUENCES

The classic theory of sequence stratigraphy considers that first-order and second-order sequences are controlled by global and regional tectonic factors, and global eustacy is the primary factor controlling the development of third-order sequences; tectonic control is linear and secondry. The Middle-Shasan Sequence was deposited between 42Ma and 50.5Ma in the Dongying Delta of thte Dongying Sag, Bohai Bay Basin. This paper proposes that the development of the Middle-Shasan Sequence occurred in the third stage of the Tertiary Dongying sagging. Both tectonic subsidence and fault development were intensive. We believe that there was strong tectonic control on the development of the Middle-Shasan Sequence. Tectonic factors changed the characteristics of stratal framework of the Middle-Shasan Sequence, whereas variation in lake level and sediment supply only changed the architecture and size of the foresets of the Dongying Middle-Shasan Delta.