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    安庆-贵池矿集区及邻区深部电性结构研究

    The deep electrical structure across Anqing-Guichi ore concentration area

    • 摘要: 长江中下游地区经历了多期次的地质构造演化具有丰富的矿产资源,对重要矿集区及其邻区的深部电性结构进行研究具有重要意义。通过对穿过安庆—贵池矿集区的一条宽频带大地电磁测深长剖面数据进行分频段以及分区反演,构建了覆盖大别造山带至下扬子地块东缘的二维电性结构模型。发现矿集区的深部电性结构与邻区的构造单元具有显著差异,大别造山带和江南隆起带与浙赣凹陷之间的地壳整体表现为高阻特征,而下扬子坳陷和江南隆起带之间存在岩石圈上地幔尺度的高导电异常体并且与地壳浅部的高导体相连。安庆—贵池矿集区的成矿机制主要为燕山期陆内俯冲以及早白垩时期的伸展作用,矿集区下地壳加厚、拆沉和上地壳丰富的断裂系统起到了重要的控矿作用。

       

      Abstract: The middle and lower reaches of the Yangtze River have experienced multiple stages of geological evolution and are rich in mineral resources. In this paper, a two-dimensional electrical structure model covering the Dabie orogenic belt and the Lower Yangtze block was constructed by inverting a long magnetotelluric profile passing through the Anqing-Guichi ore concentration area by sub-band and sub-segment inversion scheme. According to the obtained electrical structure, the lithospheric structure beneath the ore concentration area is significantly different from that of the adjacent areas. Both the crusts under Dabie orogenic belt and between Jiangnan uplift belt and Zhegan depression are characterized by high resistivity, while the lithospheric upper mantle between Lower Yangtze depression and Jiangnan uplift belt is electrically conductive with a deep conductor extending upward to the conductors in the upper crust. The metallogenic mechanism of Anqing-Guichi ore concentration area was mainly the Yanshanian intra-continental subduction and the early Cretaceous extension deformation. The thickening and sinking of the lower crust and the abundant fault system in the upper crust underneath the ore concentration area may have played an important role in mineralization.

       

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