The mineralization of the Kalatage arc, Eastern Tianshan, NW China: Insights from the geochronology of the Meiling Cu-Zn(-Au) deposit

Abstract

The Kalatage area, located in the middle of the Dananhu arc in the Eastern Tianshan, NW China, contains abundant and different types of mineralization, e.g. volcanogenic massive sulfide (VMS) Cu-Zn deposits, porphyry Cu (-Au) deposits and volcanic hydrothermal vein Cu (-Au) deposits, represents an integral component of the Central Asian Orogenic Belt (CAOB). The Meiling hydrothermal Cu-Zn (-Au) deposit is located in the core of the Kalatage area and can be studied to better understand the processes of Paleozoic Cu mineralization in the Kalatage area. This deposit hosted in the intermediate-felsic volcanic, volcanoclastic and subvolcanic rocks. The subvolcanic rocks controlled the Cu mineralization and the distributions of the orebodies. The alteration developed along the volcanic structures, where the NW-SE, NNW-SSE, NE-SW and E-W-trending faults controlled the distribution of ores. The ores mainly occur as quartz sulfide veins and stockwork quartz sulfide veins, which contain pyrite, chalcocite, chalcopyrite, sphalerite, quartz, sericite, and/or minor calcite/gypsum/barite. Here, we report new zircon U-Pb, sericite Ar-Ar and sulfide Rb-Sr ages to constrain the geochronological framework of the Meiling deposit. The mineralization-related quartz porphyry yields a weighted mean age of 298.7 ± 2.9 Ma; the sericite from the phyllic alteration zone of the M2 orebody yields a plateau age of 265 ± 17 Ma and a consistent inverted isochron age of 261 ± 10 Ma; and the syngenetic sulfides of the M1 and M12 orebodies yield Rb-Sr isochron ages of 299 ± 3 Ma and 301 ± 4 Ma, respectively. All of these ages indicate that the metallogenic epoch of the Meiling deposit occurred in the late Carboniferous (300 Ma). Furthermore, combined with the mineralization ages of the early Silurian Honghai VMS deposit and the middle Devonian Yudai porphyry deposit, our data suggest that the the Kalatage island arc is a long-lived arcs and controls to formed the VMS-type deposit in the immature arc during the Early Silurian, the adakitic intrusions related porphyry-type deposit in the mature arc during the Middle Devonian, and the subvolcanic intrusions related volcanic hydrothermal vein-type Cu(Zn/Au) deposits in the shallow crust of the mature arc during the late Carboniferous.