Tectonomagmatic controls of porphyry-type deposits linked to the Late Paleozoic Gondwanide magmatic arc: insights from the Permian Tres Amigos Prospect, Western Precordillera, Argentina

Abstract

Assessing the timescales and controls of porphyry-type deposits, which are the main source of Cu for the energy transition, is fundamental to develop exploration strategies. The Tres Amigos porphyry prospect (267.4 ± 4.3 Ma), located in the Western Precordillera of Argentina, is part of the Permian copper metallogenic belt, which is highly prospective for copper exploration given its vast extension and the presence of numerous occurrences related to porphyry Cu deposits. A new K–Ar age of 267.4 ± 4.3 Ma constrains the timing of the Tres Amigos magmatic-hydrothermal system. The geochemistry of magmatism genetically related to mineralization reveals an arc affinity and an adakite-like signature with source magmas evolving under progressive crustal thickening conditions, which resulted in a relatively high-pressure (amphibole) residual mineralogy in the source. Mineralizing magmas have a hydrous and oxidant character, typical of fertile suites worldwide. On the other hand, structural information reveals an association with orogen-parallel dextral strike-slip-dominated transpression. These characteristics are consistent with the Permian transpressional regime in the Andean region, which triggered crustal thickening and consequent development of fertile magmas. Comparisons with other Permian porphyry Cu-type deposits indicate along-strike tectonic segmentation of the margin at 31 S, implying major differences in arc magma fertility. In this context, the segment south of 31 S may have the largest economic potential of the Permian belt.