TECTONO-MAGMATIC EVOLUTION AND DISTRIBUTION OF PORPHYRY CU SYSTEMS IN THE CENTRAL TETHYS REGION OF TURKEY, THE CAUCASUS, IRAN, AND SOUTHERN PAKISTAN
Integration of these data with the location of 41 identified porphyry Cu deposits—including the giant Reko Diq (Pakistan), and world-class Sar Cheshmeh (Iran), Sungun (Iran), and Kadjaran (Armenia) systems—and 317 porphyry Cu prospects shows that magmatism can be explained in terms of plate tectonic principles, including post-subduction processes, which also played a key role in porphyry generation. However, uplift and burial events also contributed to observed metallogenic patterns.
Twenty six partially overlapping Late Triassic to recent magmatic belts were recognized as permissive for porphyry mineralization. About 65% of all porphyry sites occur in only 5 belts, which also host most of the known Cu resources. 60% are related to continental arcs; 20% to island arcs or backarcs; and 20% to post-collisional settings. Of the known porphyry Cu deposits, sub-equal fractions are distributed among these three settings. As elsewhere around the world, the largest deposits occur in either compressional continental arc or extensional post-collisional environments.
Distribution of known porphyry occurrences is also related to the level of erosion currently exposed by the interaction of exhumation and burial processes. Magmatic belts with numerous known porphyries exhibit sub-equal areas of coeval plutonic and volcanic units and lesser cover rocks. Belts with fewer known porphyries display either high or low volcanic-to-plutonic ratios and/or greater cover, pointing to crustal levels that are too shallow or too deep for exposure of porphyry-related mineralization.
This study contributes to the understanding of the distribution and nature of magmatism and associated porphyry mineralization in the Central Tethys, a region that is receiving renewed attention. It also provides an improved framework for establishing comparisons with other porphyry belts worldwide.