贵州松桃地区深部电性结构特征与锰矿成矿背景关系研究

Study on the relationship between the deep electrical structure characteristics and the background of manganese ore formation in Songtao area,Guizhou,China

本文以贵州松桃地区的杨立掌—三阳成锰盆地为研究对象,完成了一条跨过杨立掌断裂、猴子坳向斜、三阳断裂等主要地质单元的宽频大地电磁(MT)剖面,通过深部电性结构的研究对锰矿的空间展布、成矿背景、控矿构造等方面开展研究.大地电磁反演解释结果表明:(1)浅部(2.5 km深度以上)电性结构大致可划分为"高阻-低阻-高阻"三层电性结构,中间低阻层的底界面为锰矿所在的大塘坡组一段(Nh1d1);(2)猴子坳向斜-3 km海拔位置的电性表现为低电阻特征且向深部延伸,推断存在一个深大断裂,此位置可能为该盆地的沉降中心;(3)研究区的锰矿可能是因为壳幔气随深部张性断裂形成的通道上涌带来丰富的含锰物质随后在适合的成矿条件下于杨立掌—三阳成锰盆地富集成矿.

This article takes the Yanglizhang-Sanyang Manganese Ore Basin in Songtao area of Guizhou as the research object, completing a broadband magnetotelluric section across major geological units such as Yanglizhang Fault, Houziao Syncline, Sanyang Fault, etc. Research on manganese ore’s spatial distribution, metallogenic background, ore-controlling structure, etc. through the deep electrical structure.The interpretation result of magnetotelluric inversion shows:(1) The electrical structure in the shallow part(above 2.5 km depth) can be roughly divided into three-layer electrical structures of "high resistance-low resistance-high resistance". The bottom interface of the middle low-resistance layer is the first member of Datangpo Formation(Nh1d1) where the manganese ore located.(2) The resistivity value at the elevation of the Houziao Syncline-3 km is characterized by low resistance and extends to the deep. It infers that there is a deep fault and may be the subsidence center of the basin.(3) The manganese ore in the study area may be due to the upwelling of crust and mantle gas along the channel formed by the deep tensile fracture, which brings abundant manganese-containing materials and then enriching the ore in the Yanglizhang-Sanyang Manganese Basin under suitable mineralization conditions.