Application of Singular Value Decomposition (SVD) to the Extraction of Gravity Anomalies Associated with Ag-Pb-Zn-W Polymetallic Mineralization in the Bozhushan Ore Field, Southwestern China

Abstract

The Bozhushan Ore Field, located at the western margin of the South China Block, is an important area for Ag-Pb-Zn-W polymetallic mineralization which may be associated with the Late Cretaceous granitic magmaism. In this paper, the singular value decomposition (SVD) was effectively applied to decompose gravity data at scale of 1: 50 000 within the Bozhushan Ore Field to extract deep ore-finding information. Two gravity anomaly images displaying different scales of the ore-controlling factors were obtained. (1) The low-pass filtered image may reflect the deeply buried geological structures, hidden intrusions and concealed ore bodies. The negative gravity anomaly may reflect the overall distribution of granite bodies in the Bozhushan Ore Field. One negative gravity anomaly area may correspond to the exposed part of the Baozhushan granitic intrusion and the other corresponds to the concealed part of the granitic intrusion. The granitic intrusions are the main ore-controlling factors in this ore district. (2) The band-pass filtered image depicts the shallow concealed geological structures and geological bodies within this study area. There are two obvious negative gravity anomalies, which may be created by the hidden granites at different depths at both northwestern and southeastern sides of the exposed granitic intrusion. Thus the two negative gravity anomalies are favorable prospecting areas for various type of polymetallic ore deposits at depth. The gravity anomalies extracted by using the SVD exactly reflect the distribution of the ore deposits, structures and intrusions, which will give new insights for further mineral exploration in the study area.