新疆准噶尔东北缘玉依塔斯斑岩Cu-Au-Mo矿床成岩成矿时代及成矿潜力OA

The Yuyitasi is a newly discovered,medium-sized porphyry-type Cu-Au-Mo deposit located in the northeast-ern Junggar region,with orebodies hosted by Early Devonian quartz diorite and diorite.Geochronological study was conducted on the main intrusions and strata of the district.Systematic LA-ICP-MS U-Pb dating of zircons yields ages of(426.2±1.6)Ma for tuff,(409.1±3.3)Ma for pyroxene diorite,(396.8±3.0)Ma for mineralized quartz diorite,(387.6±4.2)Ma for diorite,and(388.0±10)Ma for granite,indicating a multi-stage magmatic em-placement history.The emplacement age of the ore-bearing quartz diorite is consistent with the Re-Os age dating of molybdenite from the deposit((395.7±5.6)Ma).Geochemically,the mineralized quartz diorite is enriched in large-ion lithophile elements and depleted in high-field-strength elements,displaying a typical island-arc affinity and suggesting that the porphyry Cu-Au-Mo mineralization at Yuyitasi formed in an Early-Middle Devonian is-land-arc setting.Compositional variations among the intermediate-felsic intrusions are chiefly controlled by dif-ferent degrees of partial melting in the source.Whole-rock Dy/Yb decreases markedly with increasing SiO2,indi-cating fractional crystallization of amphibole at source area during magmatic evolution and providing a plausible explanation for the adakitic signature of the ore-forming magma.Taken together with the regional magmatic-tec-tonic framework and metallogenic conditions,these results suggest that the area surrounding the Yuyitasi still holds significant potential for discovering large porphyry Cu-Au-Mo deposits.