New paper about pluton emplacement: La Gloria Pluton (El Alfalfal), Colorado River, Cajón del Maipo, Central Chile
We presentin the first paper resulting from our research project entitled ‘The role ofshallow magma reservoirs during formation of giant ore deposits’. The paper was published in the prestigiousjournal ‘Geology‘ with the title ‘Lateral magma propagation during theemplacement of La Gloria Pluton, central Chile’. Authors belongs to GeoExpedition (Chile), ETHZürich (Switzerland) and University of Chile (Chile).
The paper is about the emplacement of La Gloria Pluton (commonly known as Alfalfal by local climbers) and include new U-Pb zircon ages and combines them with previous data of mineral and magnetic anisotropies. Results indicate that crystallization occurred mostly within an interval between 11.3–10.2 Ma, with a pattern of decreasing ages along the pluton axis from south to north. The progression of zircon ages can be explained either by gradual northwestward migration of the feeder zone that supplied magma to the shallow pluton or, more likely, by shallow lateral magma propagation southeastward from a fixed feeder zone located beneath the northern margin of the pluton. The age progression, together with existing data of subhorizontal mineral and magnetic lineations in the LGP parallel to the pluton axis, indicate lateral propagation of magma during reservoir construction along the hinge of an anticline of the volcanic host sequences. In addition to controlling the position of possible volcanic output, such horizontal migration of silicic magmas in the upper crust significantly increases the surface footprint over which fluids are exsolved and outgas, strongly decreasing the potential for magmatic–hydrothermal ore formation above laterally emplaced laccoliths in the shallow crust.