关键词: 早白垩世；地球化学；侵入岩；岩石成因')">早白垩世；地球化学；侵入岩；岩石成因, 俯冲；勃利双兴铜矿床

Abstract:

Cu polymetallic deposits are developed in the Bolishuangxing area, Heilongjiang Province. The ore-forming rock masses (granodiorite and granodiorite porphyry) are closely related to Cu deposits. In order to determine its mineralization era and geodynamic background, based on field survey work, this paper investigate the petrographic, chronological, and geochemical characteristics of intrusive rocks in Cu deposits of Bolishuangxing area, and explores the formation age, petrogenesis, and tectonic background of the intrusive rocks in the study area.The results show that the LA-ICP-MS zircon U-Pb products of Late Mesozoic Early Cretaceous magmatic activity (granodiorite at (120.94 ± 0.70)Ma, granodiorite porphyry at (120.88 ± 0.61)Ma ), which indicates that the formation time in Cu deposits of Bolishuangxing area was approximately 120.9 Ma, consistent with the peak period of mineralization in the region. Research on rock geochemistry shows that granodiorite and granodiorite porphyry contain(w(SiO₂)(61.04%-67.08%), w(Al₂O₃)(14.07%-15.86%), w(Na₂O+K₂O)(6.40%-7.15%),w(TFeO)(4.52%-6.69%), w(CaO)(2.30%-4.43%), δEu(0.74-1.27)), the europium anomaly is not obvious. They are enriched in light rare earth elements and large ion lithophile elements(Rb, Ba, Sr, etc.), and relatively deficient in heavy rare earth elements and high field strength elements (Nb,Ta,Zr, etc.). The magma source area is partial melting of newly enriched lower crustal material, showing I-type granite characteristics. Based on relevant research results, it is considered that the geodynamic setting of the formation of granodiorite and granodiorite porphyry in the study area is an extensional environment formed by the subduction and retreat of the ancient Pacific plate towards the Eurasian continent.

Key words: Early Cretaceous')">Early Cretaceous, geochemistry, rocks')">intrusive rocks, petrogenesis, sbduction, deposits of Bolishuangxing area')">Cu deposits of Bolishuangxing area