Petrogeochemical evolution of calcalkaline, shoshonitic and adakitic magmatism associated with Kerman Cenozoic arc porphyry copper mineralization, southeastern Iran: A review

Whole geochemical data are used to assess the petrogeochemical evolution and ore potentiality of different magmatic phases in the Kerman Cenozoic copper arc. There are at least five Eocene to Pliocene-Pleistocene volcano-plutonic magmatic episodes, marking the transitional from the continental arc calcalkaline, shoshonitic and adakitic to syn- to post-collisional alkaline magmatism. One of the most important episodes of the magmatism is linked to the Oligo-Miocene granodioritic-quartz monzonitic-granitic rocks of the Jebal-e-Barez type (second magmatic phase) that crosscut the first phase of Eocene volcanic rocks. The Jebal-e-Barez type granitoids mark the first phase of economic porphyry copper deposits (Sarcheshmeh and Meiduk). These granitoids and the Eocene volcanic rocks are enriched in K2O, LILE and LREE, indicating a high-K calcalkaline and shoshonitic magmatism of continental arc setting. The high copper contents (0.27–0.82% Cu) and low gold values (60–82 ppb) reflect the development of mineralizing systems with this continental arc setting. The Middle-Upper Miocene Kuh-e-Panj pelean dacitic (third magmatic phase) and their cogenetic granitoid rocks (fourth magmatic phase) are enriched in LILE, LREE, Sr, depleted in Y and Yb, and on Sr/Y-Y diagram illustrate a continental arc adakitic affinity. The Upper Miocene Kuh-e-Panj type porphyritic granitoids intrude into the pelean type dacitic volcanism and form the second phase of low grade (0.1–0.46% Cu) porphyry copper ores. The fifth phase of magmatism is related to the Pliocene-Pleistocene syn-to post-collisional K-rich alkaline basaltic lavas and lamprophyric dikes that formed by partial melting of the K-rich metasomatized mantle. Hydrothermally altered granitoids from different mines are depleted in Y, Yb, Zr, P, Ti and REE, thus show pseudoaffinity to the syn-post-collisional, adakitic or island arc calcalkaline-tholeiitic affinity. The low copper grade in nonproductive granitoids or weakly mineralized porphyry copper deposits may had been related to several factors; the interaction of primary garnitoid magma with organic-rich sedimentary basement host rocks that led to the low oxygen fugacity (below FMQ), Ca-enriched meteoric waters of low salinity, low fracture density in the porphyry stock and vapour transport of hydrothermal copper complexes to the distal part of the porphyry system. [Display omitted] •The Kerman Cenozoic porphyry copper arc includes five magmatic phases.•The arc displays calc