Geochemical Characteristics and Zircon U-Pb Geochronology of Diabase in the Jinchanghe Mining Area, Western Yunnan, SW China: Implications for Tectonic and Magmatic Evolution of the Baoshan Block

Abstract

The Jinchanghe Fe-Cu-Pb-Zn polymetallic deposit is located in the northern Baoshan block in the Sanjiang metallogenic belt, southwestern China, and is one of the major large-scale Pb-Zn polymetallic deposits. This region is characterized by numerous diabase intrusions; however, research work is limited. This study elucidated systematic geochemistry and chronology of the diabase closely associated with orebodies in Jinchanghe to provide constraints for magma evolution. The results indicated that the Jinchanghe diabase was enriched in CaO, MgO, and Al2O3 and depleted in TiO2 and P2O5. Large ion lithophile elements were depleted, while for high field strength elements, the ratio of LREEs but depleted in HREEs. The zircon U-Pb dating results suggested that the diabase age could be divided into two stages, indicating the occurrence of two-stage tectonic-magmatic events in the Late Triassic and Early Cretaceous. The results also suggested that the metallogenic age of the Jinchanghe deposit is the Early Cretaceous. Moreover, the age was closely related to the collision after the closure of the mid-Tethys Ocean in the Early Cretaceous. Therefore, the results of this study provide new evidence for the tectonic-magmatic evolution and mineralization of the Baoshan block.

Sources and Ore-Forming Environment of the Jinchanghe Pb-Zn Polymetallic Skarn Deposit, Baoshan Block, SW China: Constraints from Cu-S Isotopic and Trace Elemental Compositions of Sulfides

“…These faults do not show any relationship with the mineralization. Isotopic U-Pb dating of garnet from the Jinchanghe skarn deposit yielded an age of 520 to 496 Ma [6], probably implying that the formation of the Jinchanghe skarn Pb-Zn polymetallic deposit was the result of the subduction of Proto-Tethys Ocean. Extensive hydrothermal activity has led to significant alteration of the wall rocks of Jinchanghe deposit, showing vertical zonation.…”

“…The Jinchanghe large scale Pb-Zn polymetallic deposit is one of the typical distal skarn deposits in the Sanjiang metallogenic belt, southwest China [1][2][3]. Previous studies about the Jinchanghe deposit mainly focused on deposit geology [3,4], timing of mineralization [5,6], ore-forming fluid [3,7] and isotopic geochemistry [3,4,8], providing some reliable evidence for revealing the formation and evolution processes of this deposit. However, the studies about the sources of ore-forming metals and trace elemental geochemistry of sulfides are still insufficient, which hinders the further understanding of the sources and mineralization processes of the Jinchanghe skarn Pb-Zn polymetallic deposit.…”