Contrasting timescales of metal fluxes in porphyry copper systems from coupled physicochemical processes of magmas, rocks and fluids
Year: 2025
Type: article
Abstract: Volatile degassing from hydrous magma reservoirs controls the formation of porphyry copper deposits. Geochemical studies suggest that water-rich magmas may be more prone for ore formation, with fluid-melt partitioning potentially producing particularly metal-rich fluid stages. However, the coupled physicochemical processes at the magmatic-hydrothermal transition remain elusive, because they depend on non-linear properties of magmas, fluids and rocks. For this study, we further developed a numerical model for magma convection, volatile degassing, hydraulic fracturing and fluid flow by modifying its permeability response to brecciation and introducing chemical fluid-melt partitioning. We investigate the role of intrusion depth, water content and distribution coefficients on degassing and ore formation. The results show how magmas can self-organize into distinct degassing stages with contrasting timescales of metal fluxes. Depth and water content control the amount of fluids released by an initial short-lived tube-flow outburst event, leading to brecciation and a first mineralization event in shallow porphyry-epithermal levels for high distribution coefficients. Further cooling leads to continuous fluid release at lower rates, producing a second mineralization event at deeper levels. Our results suggest that near-saturated water contents of voluminous magma reservoirs in combination with low fluid-melt distribution coefficients support the formation of large porphyry deposits.
Source: Scientific Reports
Authors: Yulia Gruzdeva, Philipp Weis
Institutions: University of Potsdam, GFZ Helmholtz Centre for Geosciences
Language: English
Subfield: Geophysics
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,690
Funder: Deutsche Forschungsgemeinschaft
OpenAlex ID: W4413257342