The architecture of the porphyry-metal system as a prospecting stratagem in the Southern Rocky Mountains

Abstract

A model of the porphyry-metal system characteristic of the consanguineous Cretaceous and Tertiary igneous rocks and associated ores of the southern Rocky Mountains is constructed from the bits and pieces exposed in the Colorado mineral belt and the San Juan volcanic field. Hydrothermally altered rocks in a part of the areas of mineralized rock associated with the Platoro caldera are matched against the model, to locate and to characterize latent mineral deposits for optimal prospecting and exploration. The latent deposits are two stockwork molybdenite deposits (porphyry-molybdenum) and one or two copper-gold-silver chimney deposits.

Postcaldera intrusive magmatism at the Platoro caldera complex, Southern Rocky Mountain volcanic field, Colorado, USA

“…For the amphibole-bearing intrusions of the Platoro magmatic systemthe Bear Creek monzonite, Cataract Creek monzonite, Lake Annella andesite porphyry, hornblende dacite dikes, and sanidine dacite dikes-amphibole is commonly euhedral and commonly intergrown with plagioclase, suggesting it crystallized early. The H 2 O contents of these magmas were likely >4-6 wt%, as required to stabilize amphibole (Naney, 1983;Richards, 2011;Richards et al, 2012;Blatter et al, 2017). Plagioclase-amphibole thermometry for these units constrains the temperature range for their magma storage to be between 960 and 850 °C for the Lake Annella and Bear Creek intrusions and between 880 and 820 °C for the Cataract Creek monzonite and Ranger Creek hornblende dacite dike.…”

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

“…Jones (1992) examined the gold distribution in known gold-bearing porphyry copper systems and defined four categories of gold-bearing porphyry copper systems: (1) a central copper-gold zone; (2) an intermediate gold zone; (3) a distal gold zone; and (4) multiple gold zones. The intermediate gold zone consists of gold mineralization in an intermediate position between the central copper zone and the lead-zinc zone of porphyry copper districts that mostly occur within the pyrite halo (e.g., Neuerburg, 1978;Sillitoe, 1983Sillitoe, , 1988Sillitoe and Bonham, 1990).…”