Exploration of Metallogenic Structure of Manganese Ore Using Magnetotelluric Method: A Case Study in Minle Region, Hunan Province, China

The Minle manganese (Mn) deposit is a typical Mn-bearing deposit in the Datangpo Formation in southern China. The metallogenic environment and associated changing processes directly determine the migration, enrichment, and precipitation of Mn. To have a better understanding of the metallogenic structure, magnetotelluric (MT) method was performed to explore the Minle deposit. Electrical spindle analysis of MT data was conducted based on the Swift decomposition and the phase tensor decomposition, and inversion of the transverse-electric (TE) and transverse-magnetic (TM) models was carried out using the Occam inversion method. The results revealed that the main structural strike of the MT section was approximately 37° north to east and obtained the distribution characteristics of the deep electrical properties in the study area. The “concave structure” in the resistivity model is the main geophysical marker for delineating the Mn-ore body. In the metallogenic structure of Mn ore, a “funnel-shaped structure” of the strata was found, which provided favorable space for the percolation and enrichment of Mn deposits. The results of this study will be helpful in improving geophysical prospecting techniques for sedimentary Mn deposits in southern China.