Delineation of sedimentary bauxite deposits in Shaanxi Province using the gravity and transient electromagnetic methods

Abstract

In this study, a proposed method integrating gravity and transient electromagnetic (TEM) surveys was used for bauxite prospection in Shaanxi Province, China. Although the gravity method enables the identification of interfaces related to mineralization, it is unsuitable for determining the location and burial depth of such an interface. Conversely, the TEM method can accurately detect the burial depth and location of an interface, and thus, its integration with the gravity method can enable the determination of burial depth and shape for interfaces related to the mineralization of bauxite ore bodies. To verify the effectiveness of the integrated approach, gravity and TEM surveys were first conducted in an area in Puxian County, Shaanxi Province, China, which hosts known bauxite deposits. Next, Ordovician limestones associated with depressions were delineated using high-precision gravity survey, and interfaces likely to be related to mineralization were identified. These potential regions were verified using TEM data, and their locations were evaluated. Bauxite ore was identified on the interfaces between limestone and the basal surface of overlying strata, and this was validated using drilling results. This integrated approach was then extended to an unexplored area in Heyang County, Shaanxi Province, and could be applicable to other sedimentary bauxite deposits in the North China Craton.