基底性质对断裂构造的影响:以琼东南盆地为例

Influence of Basement Property on the Fracture Structure:A Case Study of the Qiongdongnan Basin

影响断裂凹陷内的断裂系统演化的原因包含多种因素,此次研究针对先存断裂及基底性质对断陷盆地的影响,通过物理模拟实验方法探究裂谷盆地断裂发育的构造演化过程。根据对琼东南盆地的地震剖面图的解释分析,盆地东部和西部的凹陷显示不同的凹陷构造形态,实验结果显示,先存断裂的位置和走向影响区域凹陷的演化和平面展布,在先存断裂影响的区域演化形成地堑构造,在无先存断裂影响的区域则演化形成地垒构造;韧性基底的上覆地层拉伸演化为复式半地堑构造,而刚性基底的上覆地层呈铲状半地堑构造,在不同基底性质影响下的构造变形模式和琼东南盆地东西部的差异构造样式基本相符,一定程度上说明了基底性质的差异对琼东南盆地东部和西部凹陷在断裂组合形态差异方面具有影响作用,为研究供给油气运移聚集成藏的断裂系统演化提供了思路。

There are several factors influencing the formation of fracture system.In this paper,three scaled analog sandbox models were constructed to simulate the tectonic evolution of fault in rift basin,to explore the tectonic evolution of Qiongdongnan basin during the main fracture stage.According to the interpretation of 2D seismic section,the depression in eastern and western Qiongdongnan Basin shows different tectonic forms.Model results showed that the evolution and development of adjacent depression is affected by the position and direction of the fault-margin affects,and the basement property had a significant influence on the tectonic evolution.The formation of graben structure is affected by pre-existing fault,the regional tectonic evolution formed horst without pre-existing fault.The compound half-graben occur when the basement develop ductile deformation,and the shovel-like half-graben of structural style occur when the basement develop brittle deformation.Based on the model results,it is proved that the basement property plays an important role in developing different kinds of fault combination in the eastern and western Qiongdongnan Basin,which provide the paths for studying the fracture system of hydrocarbon migration and accumulation.