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.

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. [ABSTRACT FROM AUTHOR]