Petrology of the Miocene igneous rocks in the Altar region, main Cordillera of San Juan, Argentina. A geodynamic model within the context of the Andean flat-slab segment and metallogenesis

Phyllosilicates geochemistry and distribution in the Altar porphyry Cu-(Au) deposit, Andes Cordillera of San Juan, Argentina: Applications in exploration, geothermometry, and geometallurgy

“…These sequences were assigned to Abanico, Coya-Machalí, and Cura-Mallín formations (e.g., Jordan et al, 2001;Charrier et al, 2002;Kay et al, 2005;Farías et al, 2008). During the early Miocene , this segment had a subducted slab geometry similar to that currently observed in the normal-slab segment at 35°S, and a crustal thickness of 35-40 km Maydagán et al, 2011). (Kay and Mpodozis, 2002).…”

“…The Altar porphyry Cu-(Au) deposit (31°29′ S, 70°28′ W), located in the Cordillera Principal of SW San Juan Province, Argentina, is a large copper deposit (995 Mt, 0.35% Cu, 0.083 g/t Au; Marek, 2014) and is one of the few examples in the world in which it is possible to observe the transition between the epithermal high sulfidation siliceous ledges and the associated porphyry deposit. Maydagán et al (2011Maydagán et al ( , 2014 conducted the first geological mapping, geochronologic and geochemical investigation of the Altar magmatic rocks. A subsequent study of the different generations of Altar veins based on cathodoluminescence (CL) imaging, trace elements in quartz, and fluid inclusion microthermometry permitted differentiate quartz generations precipitated during different mineralization and alteration events and relate sulfides to a specific generation of quartz (Maydagán et al, 2015).…”

Chlorite, white mica and clay minerals as proximity indicators to ore in the shallow porphyry environment of Quebrada de la Mina deposit, Argentina

“…In the study area, the oldest exposed rocks comprises a late Carboniferous tonalitic batholith dated at 297 Ma (Maydagán, 2012) and Cretaceous volcanic and sedimentary rocks present along the Argentinian-Chilean boundary (Mpodozis et al, 2009). The QDM district is hosted by early Miocene volcanic rocks (Maydagán et al, 2011) which are equivalent to the Abanico Formation in Chile (Klohn, 1960), the Pachón Formation in the vicinity of the Los Pelambres deposit, the Coya Machalí Formation in the El Teniente area (Charrier et al, 2002) and the Doña Ana Group of the El Indio belt (Kay and Mpodozis, 2002).…”

SULFIDE COMPOSITION AND ISOTOPIC SIGNATURE OF THE ALTAR Cu-Au DEPOSIT, ARGENTINA: CONSTRAINTS ON THE EVOLUTION OF THE PORPHYRY-EPITHERMAL SYSTEM

“…The Altar lower volcanic complex is composed of basaltic andesite and andesite-dacite lava flows, lapilli tuff, and pyroclastic breccia, and grades upwards to an upper unit of compacted and thick massive tuff (rhyolite). The lower volcanic complex is part of an early Miocene magmatic arc (20.8 Ma ± 0.3 Ma and 21.6 ± 1.2 Ma; U-Pb ages, Maydagán et al 2011, Maydagán 2012) formed above a normal subduction zone whose magmas underwent fractional crystallization and crustal contamination. Porphyritic andesite-dacite intrusions and breccias of the Altar upper subvolcanic suite intrude the volcanic rocks of the lower volcanic complex (Fig.…”

“…1B) and represent a late-middle Miocene magmatic arc (11.75 ± 0.24 to 8.9 ± 0.4 Ma U-Pb ages, Maydagán et al 2013a) formed above a shallow subduction zone. They comprises a pre-mineralization porphyry, three mineralized intrusions and associated breccias, two post-mineralization porphyries, and a late post-mineralization matrix-supported breccia (Maydagán et al 2011, Maydagán et al 2013a). These three mineralized intrusions and breccias formed two magmatic hydrothermal centers with mineralization located in the east valley (the oldest) and the central ridge (the youngest; Fig.…”