Application of tectonic primary halos in the exploration of deep concealed ore bodies: A case study of the Niuxingba plumbum-zinc-gold-silver deposit in Yinkeng, southern Jiangxi

The Niuxingba plumbum-zinc-gold-silver deposit (the Niuxingba deposit) occurs in the Yinkeng ore field at the intersection of the EW-trending Nanling metallogenic belt and the NNE-striking Wuyishan metallogenic belt. It is a typical hydrothermal vein deposit under the strict control of fault structures, with ore bodies occurring as vein groups. To predict the deep prospecting potential of the No. V31 major ore belt (body) of the Niuxingba deposit, this study systematically investigated the axial (vertical), transverse, and longitudinal geochemical characteristics and zoning of tectonic primary halos of the ore belt (body) based on the geological characteristics of the deposit. Then, this study determined the axial zoning sequence and the geological-geochemical model of tectonic primary halos. It was confirmed that this model was correct, reasonable, and reliable using the multivariate statistical method. The results of the geological-geochemical model show that: ① the front halo of the Niuxingba deposit has F as the indicator element; ② the near-ore halo has two types of indicator elements: the gold mineralization-related As-Au element association in the middle and upper parts of the ore body and the Pb-Zn-Ag mineralization-related Hg-Zn-Pb-Ag-Cu-Bi-Sb element association in the middle part of the ore body; ③ the rear halo has the Mo-Cr-Co-Ni element association as indicator elements; ④ the anomaly centers of the front, near-ore, and rear halos are about 200~300 m apart axially, suggesting significant coexistence of front and rear halos and the presence of inflection points of the near-ore halo broken line. Furthermore, the transformation of low-moderate-temperature Pb-Zn-Ag-Au mineralization into moderate-high-temperature Cu-Zn mineralization occurs eastward. These characteristics indicate that the No. V31 main ore belt (body) has a pitch direction of east and a large extension toward the deep part (to an elevation of -200 m at least), implying that blind ore bodies may occur. As verified by deep drilling in the eastern concealed area (the lowest ore-controlled elevation of the No. 367 survey line: -165 m), the eastern deep part of the No. V31 ore belt (body) has a high potential for increasing reserves.