胶莱盆地莱阳凹陷莱西断层断裂性质及成因机制

为了明确胶莱盆地莱阳凹陷莱西断层的断裂性质及成因机制，利用莱阳凹陷重力资料及新采集处理二维地震资料，对莱西断层进行识别与描述，并对其几何学特征和形成机理进行分析。莱西断层发育带状展布、花状构造、海豚效应等构造样式，并且断层两侧地质体沿断层走向左行错开约4.4km，是一条典型的左行走滑断层。晚白垩世末期-古新世时期，研究区构造应力场为NEE-SWW向挤压，牟平-即墨断裂带由晚白垩世早期的伸展作用转换成右行走滑，而莱西断层剪切方向与其相反，是牟平-即墨断裂带的共轭左行走滑断层。莱西断层并不控制白垩纪地层的沉积，因此不是莱阳凹陷的西部控凹断层，而是凹陷内部的一条分带断层，在其切割作用下莱阳凹陷被分成东西2部分。

Fracture properties and formation mechanism of Laixi fault in Laiyang Sag,Jiaolai Basin

The Laixi fault was identified and described, and its geometric features and formation mechanism were also analyzed based on the gravity data and new 2D seismic data of the Laiyang Sag in order to clarify the fracture properties and formation mechanism of the Laixi fault. Several structural styles were found in the Laixi fault, such as zonal distribution, flower structure and dolphin effect. The geologic bodies on both sides of the fault showed a sinistral offset of 4.4 km, indicating a typical sinistral strike-slip fault. From the Late Cretaceous to Paleocene, the tectonic stress field in the study area was NEE-SWW compression. The activity of the Muping-Jimo fault zone converted from extension to dextral strike-slip, while the Laixi fault had an opposite direction, which was a conjugate strike slip fault of the Muping-Jimo fault zone. The Laixi fault did not control the sediment of the Cretaceous; therefore, it was not a concave boundary fault in the west of the Laiyang Sag, but an internal split fault, which cut the Laiyang Sag into two parts.