The three-dimensional electrical structure and metallogenic prospect of the Ning (Nanjing)-Wu (Wuhu) basin and the southern adjacent area in eastern China

Abstract

The Ning (Nanjing city)-Wu (Wuhu City) volcanic basin, which is famous for its large-scale, high-grade ore deposits, is a typical iron ore district in the middle-lower reaches of the Yangtze River Metallogenic Belt (MLRYMB). The southern part of the basin is primarily covered by Quaternary strata. Few in depth studies have been conducted on this area. Due to the increasing demand for mineral resources and the controversy over regional tectonic models, some fundamental geological issues still need to be addressed. These questions include defining the characteristics of the geological structures and the mineralization prospects. Therefore, a three-dimensional (3D) magnetotelluric survey was conducted in this area to obtain a deep 3D electrical model. It was found that the Yangtze fault (CJF) and the main thrust fault (MTF) in the upper crust have the same deep (middle crust to upper mantle) setting and part of the thrust tectonics of the metallogenic belt. The southern boundary of the Ning-Wu Basin is located on a fault belt (boundary fault, BF) with a northeast-east (or east-west) strike influenced by the MTF in the southern part of the study area. Bounded by the BF and MTF, the southeastern part of the study area exhibits signs of uplift. With the recent discovery of a large porphyry copper deposit to the southeastern part of the study area, which is located in an uplift structure similar to the one south of the Ning-Wu Basin, this local uplift could have potential mineralization prospects based on a previous mineralization theory developed for this belt.