西藏东坡蛇绿岩体深部结构的地球物理特征及其找矿意义

在西藏西部雅鲁藏布江南岸的东坡岩体进行了多种方法的地球物理探测,由地面磁测精确定位的航空磁测异常反演了东坡岩体深部磁性体范围;反射地震探测划分出了与地表出露蛇绿岩体反射波特征不同的岩体下部弱反射部位;同时,由大地电磁法确定了岩体下部的低阻体也都处于大致相同的部位。地面出露的蛇绿岩体向下延伸,整体呈锅底状,其中部具有较低电阻和弱反射波特征,同时,在1.5~3.0 km范围的磁性矿物相对较发育,可能正是含铬岩体矿化蚀变作用较强的地段,在罗布莎矿区有类似的特征,这对找矿是有利的部位。

Geophysical characteristics and prospecting significance of deep structures in Dongpo ophiolite body, Tibet

Abstract:Geophysical survey of Dongpo rock mass on the south bank of Yarlung Zangbo River in western Tibet was carried out using multiple methods, and the inversion of aeromagnetic survey anomaly precisely positioned by ground magnetic survey revealed the range of the deep magnetic body in Dongpo rock mass; seismic reflection survey delineated the weak reflection places under the rock mass with reflected wave characteristics different from those of outcropping ophiolite body; meanwhile,as confirmed by MT method, the low-resistivity bodies under the rock mass are at the roughly identical places. The outcropping ophiolite body extends downward, resembling a pot bottom as a whole, and its middle part is characterized by low resistivity and weak reflected wave. In addition, magnetic minerals are relatively developed at the depths of 1.5km-3.0 km, which might be the very section of chromium-bearing rock mass having strong mineralization and alteration; the similar characteristics were observed in the Luobusha mining area, and hence these places are favorable for ore prospecting.