Lithologic mapping test for gravity and magnetic anomalies: A case study of gravity–magnetic anomaly profile in the eastern segment of the China–Mongolia border

Abstract

An inversion calculation is usually needed to map lithologies with gravity–magnetic anomalies. A lithological-physical property correspondence can be established by combining data of regional rock density and magnetic susceptibility to build topological equations. In this study, topological calculations were performed using inversion data and combined with physical property data to interpret and map lithologies. Gravity–magnetic profiles from the eastern segment of the China–Mongolia border were used (Jining–Bainaimiao–Ha'ernaode geological–composite geophysical profile) in this paper. Based on gravity–magnetic anomaly inversion, the rock density and magnetic susceptibility data of Bainaimiao and Jining were adopted for lithological inversion. Distribution characteristics of four major types of magmatic rocks within 50km of the lower half space were obtained, and results of lithologic mapping and tectonic framework were analyzed. The position of convergence between the North China Plate and Siberian Plate was confirmed. Two tectonic stages were identified, namely, interplate squeezing and intraplate deformation. Regional gravity–magnetic field properties were analyzed to discuss the orientation and date of andesites and diorites in the northern part of the survey line. We believe that they have a northeast–southwest orientation similar to gravity–magnetic anomalies of Erenhot–Xilinhot. They resemble the igneous rock near Erenhot because they both indicate magmatic intrusion during the early Carboniferous.