Genesis and geodynamic background of the ore-bearing granodiotite porphyry of the Jilongshan copper-gold deposit in Jiurui district, Hubei Province

Abstract

Jilongshan copper-gold deposit is located in the Jiurui metallogenic district in the middle and lower Yangtze River metallogenic belt. Cu-Au mineralization of Jilongshan deposit is closely related to granodiotite porphyry. The petrogenesis of the rock is still controversially discussed. In this study, we report the U-Pb zircon chronology, major and trace geochemistry, Sr-Nd-Hf isotopic compositions of the ore-related granodiorite porphyry in Jilongshan. LA-ICP-MS zircon U-Pb geochronology of Jilongshan granodiorite porphyry is 140±1 Ma(MSWD=1.02). Geochemical results show that Jilongshan granodiorite porphyry has a relatively high content of SiO2 (62.33%~63.90%) and Al2O3 (15.24%~15.74%), and alkalis(w(K2O + Na2O) is 6.99%-7.73%). The trace elements are characterized by the relative enrichment of Rb, Ba, K, Sr, depletion of Ta, Nb. The REE characteristics show rightist features with relatively LREE enrichment with (La/Yb)N ratio of 10.55~15.95, and no obvious negative Eu anomaly. The ziron Hf isotope analysis shows low εHf (t) values, and low εNd (t) (-8.2~-9.7). These data suggested that the Jilongshan granodiorite porphyry may be derived from partial melting of enriched lithospheric mantle, mixed with ancient crustal material to a certain extent.

Keywords

• jilongshan skarn cu-au deposit
• granodiorite porphyry
• u-pb zircon age
• isotopic geochemical
• jiurui metallogenic district