重力方法在祁连山地区构造特征与岩体解释中的应用

依据地质、航磁等资料,结合实测岩石物性资料,以1∶250 000重力资料为基础对祁连山地区(张掖、刚察地区)进行综合研究。研究地质构造与地球物理特征,划分了大地构造单元,探讨了隐伏与半隐伏岩体分布。该区域经多年的重力工作,勘探面积已近3万多km²,根据重力资料研究布格重力场特征并进行分区; 对地质构造单元重新划分,对主要断裂进行探讨; 圈定隐伏与半隐伏岩体,推断其空间展布特征,并对其解释。结果表明: 祁连山地区地壳密度结构横向分区、纵向分层明显,布格重力异常场的分区特征与地质构造分区特征基本一致。结合2.5D重力剖面反演印证了新的推测结果,为综合地质、地球物理找矿提供参考。

Gravity method application in tectonic characters and rock mass interpretation of Qilian Mountains

Based on geological, aeromagnetic and other data, and combined with measured physical properties of rock, the authors conducted a comprehensive research on Qilian Mountains (Zhangye and Gangcha areas) with the 1∶250 000 gravity data. The geological structure characteristics, geophysical characteristics, division of tectonic units and distribution of concealed and semi-concealed rock mass were studied. After many years’ gravity work in this area, the exploration area has reached nearly 30 000 km². This paper has studied the characteristics of Bouguer gravity field based on gravity data and has divided the anomaly units. The geological tectonic units have been redivided and the major faults have been discussed. Concealed and semi-concealed rock mass have been identified and the spatial distributions have been speculated and interpreted. The results show that the partition and stratification of the crust density structure in Qilian Mountains are obvious, and that the partition characteristics of the Bouguer gravity anomaly field are basically the same with the partition characteristics of the geological structure. The combination of 2.5D gravity section inversion confirms the new speculations. The results will provide some reference for comprehensive geological and geophysical prospecting.