Review of Mesozoic multiple magmatism and porphyry Cu-Mo (W) mineralization in the Yidun Arc, eastern Tibet Plateau

The Yidun Arc was formed in response to the westward subduction of Garze-Litang Ocean (a branch of Paleotethys) in the Late Triassic, where abundant porphyry Cu-Mo deposits (221-213 Ma) developed along the regional NW-SE sinistral faults and emplaced in the southern portion of the arc. The ore related porphyries are mostly metaluminous or slightly peraluminous, belonging to shoshonitic high potassium calc-alkaline I-type granites, with epsilon(Hf)(t) values of -6.64 to +4.12. The ore-bearing magmas were probably derived from the partial melting of subduction-metasomatic-enriched mantle, with the contamination of underplated mafic materials. The Late Cretaceous (88-80 Ma) highly fractionated I type granite belt and related porphyry Cu-Mo deposits and magmatic-hydrothermal Cu-Mo-W deposits occur along approximately N-S-trending faults in the Yidun Arc. This belt extended across the Yidun Arc and Garze-Litang suture zone to the north and across the Yangtze Craton to the south, intruding the Late Triassic porphyry belt. The ore-related porphyries are characterized by high silica and high total alkalis, with enrichment in large ion lithophile elements (LILEs; Rb, U and IC) and depletion in high field strength elements (HFSE; Nb, Ta, P and Ti) and Ba. They have lower epsilon(Hf)(t) values varying from -9.55 to -2.75, and significant negative Eu anomalies, indicating that the ore-bearing porphyritic magmas originated from ancient middle-upper crust. Two-stage magmatism and mineralization were superimposed in the Xiangcheng-Shangri-La district. Some ore deposits comprise two episodes of magmatism and associated mineralization such as both 207 +/- 3.0 Ma granodiorite and 82.1 +/- 1.2 Ma monzogranite intruded in the Xiuwacu deposit, causing Cu-Mo-W polymetallic mineralization. To date, 11 Late Triassic porphyry Cu deposits (e.g. the Pulang giant deposit with 5.1 Mt Cu), and five Late Cretaceous porphyry Cu-Mo (W) deposits (e.g. Tongchanggou Mo deposit with 0.59 Mt Mo) have been evaluated in the XiangchengShangri-La district. The continuity and inheritance of multiphase magmatism and the new understanding of superimposed mineralization will help to guide future exploration. (C) 2017 Elsevier B.V. All rights reserved.