Chlorite and epidote chemistry of the Yandong Cu deposit, NW China: Metallogenic and exploration implications for Paleozoic porphyry Cu systems in the Eastern Tianshan

摘要

The Yandong porphyry Cu deposit in the Eastern Tianshan terrane is the largest in Xinjiang, NW China (metal reserve: 2.3 Mt Cu @ 0.67%). Three periods and six alteration and mineralization stages were identified in this study, i.e., Porphyry period (including Stage I: propylitic alteration; II: quartz-magnetite alteration; III: phyllic alteration and early mineralization); overprinting period (including Stage IV: overprinting mineralization and Stage V: late vein) and supergene period (Stage VI: supergene mineralization). Stage IV was the main Cu mineralization stage at the Yandong Cu deposit, which is characterized by the mineral assemblage of chalcopyrite + chlorite + anhydrite + calcite.