Two-dimensional geoelectrical structure of the Songtao manganese deposits in Guizhou Province, China

An audio frequency magnetotelluric (AMT) survey was conducted on the Songtao manganese deposits area in Guizhou, China, with the objective of identifying the distribution and the tectonic environment of the deposits. Using the Groom-Bailey decomposition approach in geoelectrical dimensionality analysis and the nonlinear conjugate gradient technique subsequently in inverse modeling for 202 AMT soundings, we show that AMT produces high-resolution electrical resistivity estimates for different kinds of formation. The resulting two dimensional (2D) geoelectrical structures clearly display that the manganese deposits are located at the depth about 2 km with low resistivity values (25-40 Ω·m). These deposits were formed in the lower DaTangPo formation of the NanHua system. Further, the spatial distribution and the main tectonic features of the manganese deposits are in good agreements with the geology and drilling data. Moreover, the results demonstrate the destruction and control of the concealed structure to manganese hosting rocks, and provide geophysical constraints for the further study of the manganese deposits in this area.