东营凹陷南部重力异常地质成因

Geologic origin of gravity anomaly in southern Dongying Depression

引起重力异常的地质因素非常复杂,要对其做出合理地质解释,不仅需要精细分离重力异常,而且需要与其他资料结合。从重力正演模拟出发,分析了可能产生重力异常的地质因素,以及不同地质体的重力响应形态。在此基础上,利用垂向二阶导数及其他信息增强技术,有效提取东营凹陷南部地区局部重力异常,结合地震、钻井资料,进行了地质成因推断分析,认为影响该区重力局部正异常的地质因素主要是古潜山(包括断块山和残丘山)、盖层构造以及其他如陡坡带砂砾岩体等,古潜山的分布多受大断裂控制,平面上成带连片分布;而区域重力异常则反映了该区的区域构造特征。应用效果表明,在地震成熟勘探区,高精度重力不仅可以发现一些新的地质目标,而且与地震相结合,在诸如深层构造、潜山、有规模的隐蔽性断裂等目标的落实方面,也可以发挥积极作用。

Gravity anomalies caused by geological causes are extremely complex.It is necessary to make a reasonable geological interpretation requires not only precise gravity anomaly separation,but also close integration with other informations.Beginning from the gravity forward modelling,geological factors caused gravity anomalies and their different geological body patterns in response to gravity were analyzed.Based on that,the vertical second derivative, and other technologies of enhancing information can be used for extraction of the southern Dongying local gravity anomaly. Combined with seismic and drilling data,a geological origin was analyzed.The area of local gravity anomaly of geological factors are mainly buried hills(including fault-block mountains and hammock),cap structure,as well as other structures such as steep slope glutenite and so on.The distribution of buried hill is controlled by the major fractures as zonality on plane.The regional gravity anomaly reflects the regional tectonic features of the area.Application results show that a mature exploration area with the earthquake,high-precision gravity can find not only some new geological targets,but also the targets of deep structure, buried hill,and a scale of hidden fractures combined with the earthquake,which will play an active role.