Petrogenesis and Mo mineralization of a granitic complex, Da Hinggan Mountains, NE China: insights from zircon U-Pb dating, major and trace element geochemistry, and Sr-Nd-Pb isotopes

Abstract

Abundant Cu and Mo deposits are spatially related to granitic complexes in the Nuomin area, eastern Da Hinggan Mountains, China. The petrogenesis of these deposits is investigated using data from zircon U–Pb dating, whole-rock major and trace element geochemistry, and Sr–Nd–Pb isotopic compositions. The results show that the fine-grained biotite monzogranite and medium-grained biotite syenogranite formed in a Late Jurassic (155.7 ± 3.6 Ma) collision environment, characterized by fluid–melt interaction and plagioclase differentiation. These rocks belong to the high-K calc-alkaline, K-peraluminous series, indicating that the parent magma evolved from the low-temperature partial melting of lower crust, with geochemistry consistent with Neoproterozoic oceanic crust. The monzonitic diorite porphyrite, monzonite porphyry (with a crystallization age of 130.64 ± 0.74 Ma) and quartz monzonite porphyry belong to the high-K calc-alkaline, sodic, quasi-aluminous series. The results indicate petrogenesis in a post-collisional or late-orogenic tectonic environment, characterized by interactions with CO2-rich fluid and the fractional crystallization of amphibole, biotite and apatite. The parent magma formed from the partial melting of residual Neoproterozoic oceanic crust. The circulation of mineralized fluids was related to the petrogenesis of the monzonitic diorite porphyrite, monzonite porphyry and quartz monzonite porphyry. Copyright © 2015 John Wiley & Sons, Ltd.