基于地球物理资料的临夏盆地基底性质研究

BASEMENT PROPERTY OF LINXIA BASIN BASED ON GEOPHYSICAL DATA

通过研究区近年地球物理数据,结合钻井和地质等资料以及前人研究成果,讨论了临夏盆地重磁场特征及地质意义,对研究区基底埋深进行了定性和定量分析。结果表明,临夏盆地基底是由大面积分布的花岗闪长岩等中酸性岩浆岩组成,上部为大规模的中—新生代沉积,两者之间局部夹杂着变质岩;临夏凹陷盖层整体表现为由东北向西南方向加厚的趋势,最深处位于山前地带,大约1 200 m~1 600 m;临洮凹陷盖层厚度相对较大,最深处基本沿洮河河谷呈南北向弧形带状展布,普遍大于1 000 m。

Based on the newly measured geophysical data in the study area in recent years, combined with drilling and geological data and previous research results, the characteristics of the gravity and magnetic field and geological significance of the Linxia Basin are discussed, the basement attributes of the basin are analyzed, and seismic and electrical methods are used to bury the basement of the study area. Deeply conducted qualitative and quantitative analysis. The results show that the base of the Linxia Basin is composed of a large area of granodiorite and other intermediate-acid magmatic rocks, and the upper part is a large-scale Meso-Cenozoic sedimentary depression, with metamorphic rocks interspersed partially between the two;the Linxia sag cover The whole layer shows a trend of thickening from northeast to southwest, the deepest part is located in the piedmont zone, about 1 200 m-1 600 m;the thickness of the cap layer in the Lintao Sag is relatively large, and the deepest part is basically a north-south arc belt along the Taohe valley. The spread is generally larger than 1 000 m.