Constructing the deep-spreading pattern of tectono-geochemical anomalies and its implications on the Huangshaping W–Sn–Pb–Zn polymetallic deposit in southern Hunan, China

Abstract

Huangshaping large W–Mo–Pb–Zn polymetallic deposit is a typical representative of the Cu–Sn metallogenic system in Nanling Range, South China. This deposit located in the superimposed tectonic setting of the Qinzhou–Hangzhou and Nanling metallogenic belts. Skarn-type W–Sn orebodies and hydrothermal vein-type Pb–Zn–Cu orebodies located in the faults and contact zone between late Jurassic porphyry and late Paleozoic limestone. Many studies have been conducted on the geological and geochemical characteristics of the deposit, but the comprehensive understanding of the deep-spreading pattern of the tectono-geochemical anomalies remains unclear. The geochemical data of tectonites in deep level adits (−136 m, −176 m, −256 m and −296 m) were studied the distribution characteristics of ore-forming trace elements and the depth index of tectonic geochemical anomalies. Finally, four element combination anomalies were extrated from the cluster analysis and factor analysis. They are generally consistent with the known Cu–Pb–Zn and W–Sn–Mo–Bi metallogenic systems. In addition, from altered porphyry to limestone of the Shidengzi Formation, the plane and profile anomaly contour maps delineated by different factors have regular variation characteristics. High anomalous values usually occur in the part where ore-forming porphyry changes from convex to concave. Comprehensive study trace element combination anomalies shows that the connection line of high value anomalous zones corresponds to the swelling and shrinking characteristics of porphyry, showing periodic wave-like changes. Thus, the deep index and deep-spreading pattern of ore-controlling structure were constructed. The length, width and height of the deep-seated orebodies indicated by the main anomalies are evaluated. The anomalous vertical variation indicates the migration of ore-forming fluid from SE to NW to the shallow. The strike of orebodiesy are consistent with the ore-controlling faults and dip to SE. Overall, the tectonic geochemical anomalies are consistent with the locations where the orebodies were identified, indicating that the method is feasible and effective. This study has an important significance for the layout of deep-prospecting and exploration projects in the Huangshaping deposit and even in southern Hunan.