Mineral exploration model for Lhasa Area, eastern Gangdese metallogenic belt: Based on knowledge-driven compositional data analysis and catchment basin division

Abstract

With the reduction in outcrop mines, the finding of hidden deposits has become more difficult than ever before. Traditional geochemical single element anomalies extraction, especially the ore-forming elements, are facing issues in judging regional potential mineralization, while in contrast approaches to examine geochemical association can provide more information. Along these lines, in this work, the geological knowledge and geochemical information were integrated not only to promote the understanding of regional metallogenic regularity by studying the underlying geochemical association but also to point out the important regional prospecting indicators. From our analysis, the following milestones were obtained: i) It was proposed that the main metallogenic period in the Lhasa area is concentrated in two different stages of Paleogene syn-collision and Miocene post-collision, causing three types of deposits formed, namely, porphyry deposit, skarn deposit, and hydrothermal vein deposit. Cu, Mo, Pb, and Zn were identified as the main ore-forming elements, whereas W and Au deposit were detected in some local areas, and the ore-controlling geological conditions of the aforementioned three types were simultaneously summarized; ii) Combining the existing geological knowledge with geochemical data, nine groups of compositional balances related to mineralization were selectively obtained as geochemical associations, which effectively identified the distribution of the main geological units and the mineralization range; iii) The division of the fourth-level catchment basin and the second-level catchment basin was described as an effective method to delineate the boundary of the regional mineral targets and deepen the understanding of the metallogenic regularity; iv) Based on the established regional mineral exploration model, the exploration targets of three skarn PbZn, the porphyry-skarn CuMo exploration targets of Qulong–Jiama, and the hydrothermal vein Pb-Zn-Ag/Au exploration target of Riwuduo–Nongruri were delineated.