Geological characteristics, magmatic geochemistry and petrogenic chronology of the Bagong Pb polymetallic ore spot in Ritu County, Tibet

The Bagong Pb polymetallic ore spot is located in the west of the Bangong Co-Nujiang metallogenic belt, and its tectonic unit belongs to Ritu-Duolong early Cretaceous magma arc belt. Preliminary estimation of Cu+Pb+Zn 334₁ resources is 94900 tons. Based on the results of investigation and evaluation of Cu-Pb-Zn polymetallic ore resources in the eastern Aiyongcuo area in Ritu County of Tibet, The authors investigated their geological characteristics, genesis and prospecting significance. Samples of rare earth elements, trace elements, silicate and isotopes were systematically collected and studied through large scale mapping, and the pluton which is exposed in the ore spot consists of diabase, quartz monzodiorite, granodiorite porphyry and granite porphyry. Among them, granule porphyry formed on active continental margin in early Cretaceous((112.7±0.68)Ma) seems to be most closely related to mineralization. The ore-controlling factors are mainly composed of strata, magma and structure. The metallogenic wall rocks mainly include altered tuff sandstone, altered agglomerate, altered diabase and sericite-chlorite altered rock. The ore-controlling structure mainly includes NWW-, nearly EW- and NW-trending faults. The orebody exhibits disseminated, lentoid, stockwork and aggregation forms. The authors preliminarily hold that the origin of the Bagong Cu-Pb-Zn polymetallic ore spot is of medium and low temperature hydrothermal fracture filling type. The discovery of this ore spot provides a new prospecting clue for BangongNujiang junction zone and the volcanic-magma arc on both sides of the junction zone. In addition, the prospecting direction is further expanded in this area.