Geochemical Characteristics and Zircon U-Pb Age of Medium-Fine Grained Granite of Aikengdelesite Cu-Mo deposit in East Kunlun and It’s Geological Implications

Indosinian is one of the important tectonic evolution and magmatic activity period of the East Kunlun orogenic belt, thus, the intrusive rocks of this period are critical to discuss the relationship between the tectonic evolution and the polymetallic mineralization of the East Kunlun orogenic belt. There is close relationship between the medium-fine grained granite and copper & molybdenum mineralization in Aikengdelesite Cu-Mo ore district from subduction-accretionary complex belt in southern slope of the East Kunlun orogenic belt. An comprehensive study of the geochemical characteristics, zircon U-Pb age, magma source and diagenetic tectonic environment were carried out for the medium-fine grained granite in Aikengdelesite Cu-Mo ore district, aiming to provide new evidence for the Late Paleozoic to Early Mesozoic tectonic evolution and polymetallic mineralization of the East Kunlun. The studied medium-fine grained granite is calc-alkaline series rock, with high SiO₂ (72.43% to 73.83%), high Al₂O₃ (13.10% to 13.60%) and weakly negative Eu anomaly, and is relatively enriched in LREE, Rb, Ba, Th, U and K, but relatively depleted in HREE, Nb, Ta, Ti, Sr and P. LA-ICP-MS zircon U-Pb analysis of the medium-fine grained granite yielded an Late Permian age of (253.7±1.9) Ma. The medium-fine grained granite was formed in a continental arc environment of active continental margin and related to the partial melting of lower crust.