The role of incremental magma chamber growth on ore formation in porphyry copper systems

Korges, Maximilian; Weis, Philipp; Andersen, Christine

doi:10.1016/j.epsl.2020.116584

Cited by 29 publications

(17 citation statements)

References 43 publications

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“…We envisage this extended time period as a necessary priming phase, where growth and recharge of the lower crustal magma reservoir allowed a sufficient volume of hydrous melt (> 800 km 3 ) to accumulate at depth (Rohrlach and Loucks 2005;Chiaradia and Caricchi 2017). Such magmas would be rapidly and episodically transferred to upper crustal levels (< 500 Kyr; Chelle Michou et al 2017), where cooling and degassing would allow efficient migration and accumulation of a magmatic volatile phase at apices of the batholith (Huber et al 2012;Parmigiani et al 2016;Korges et al 2020). Laterally focused fluid outbursts from the roof of the batholith would provide the source of melt and fluid to initiate and sustain the magmatic-hydrothermal system at Quellaveco (Lamy-Chappais et al 2020).…”

Section: Long-lived Magmatic Evolution Culminating In Porphyry Cu-mo Mineralisationmentioning

confidence: 99%

From long-lived batholith construction to giant porphyry copper deposit formation: petrological and zircon chemical evolution of the Quellaveco District, Southern Peru

Nathwani

Simmons

Large

et al. 2021

Contrib Mineral Petrol

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Porphyry Cu ore deposits are a rare product of arc magmatism that often form spatiotemporal clusters in magmatic arcs. The petrogenetic evolution of igneous rocks that cover the temporal window prior to and during porphyry Cu deposit formation may provide critical insights into magmatic processes that are key in generating these systems. This study documents the magmatic evolution of the Palaeocene–Eocene Yarabamba Batholith, Southern Peru, that was incrementally assembled between ~ 67 and ~ 59 Ma and hosts three, nearly contemporaneous, giant porphyry Cu–Mo deposits that formed at 57–54 Ma (Quellaveco, Toquepala and Cuajone). Whole-rock geochemistry, U–Pb geochronology and zircon trace element chemistry are reported from Yarabamba rocks that span the duration of plutonic activity, and from six porphyry intrusions at Quellaveco that bracket mineralisation. A change in whole-rock chemistry in Yarabamba intrusive rocks to high Sr/Y, high La/Yb and high Eu/Eu* is observed at ~ 60 Ma which is broadly coincident with a change in vector of the converging Nazca plate and the onset of regional compression and crustal thickening during the first stage of the Incaic orogeny. The geochemical changes are interpreted to reflect a deepening of the locus of lower crustal magma evolution in which amphibole ± garnet are stabilised as early and abundant fractionating phases and plagioclase is suppressed. Zircons in these rocks show a marked change towards higher Eu/Eu* (> 0.3) and lower Ti (< 9 ppm) compositions after ~ 60 Ma. Numerical modelling of melt Eu systematics and zircon-melt partitioning indicates that the time series of zircon Eu/Eu* in these rocks can be explained by a transition from shallower, plagioclase-dominated fractionation to high-pressure amphibole-dominated fractionation at deep crustal levels from ~ 60 Ma. Our modelling suggests that any redox effects on zircon Eu/Eu* are subordinate compared to changes in melt composition controlled by the fractionating mineral assemblage. We suggest that growth and intermittent recharge of the lower crustal magma reservoir from ~ 60 Ma produced a significant volume of hydrous and metallogenically fertile residual melt which ascended to the upper crust and eventually generated the three giant porphyry Cu–Mo deposits at Quellaveco, Toquepala and Cuajone from ~ 57 Ma. Our study highlights the importance of high-pressure magma differentiation fostered by strongly compressive tectonic regimes in generating world-class porphyry Cu deposits.

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Section: Long-lived Magmatic Evolution Culminating In Porphyry Cu-mo Mineralisationmentioning

confidence: 99%

From long-lived batholith construction to giant porphyry copper deposit formation: petrological and zircon chemical evolution of the Quellaveco District, Southern Peru

Nathwani

Simmons

Large

et al. 2021

Contrib Mineral Petrol

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“…Quantifying the dynamic behavior of mass and heat transfer in porphyry systems can be approached by numerical simulations using models that can handle high-temperature multi-phase flow of H 2 O-NaCl fluids in porous media 28 . These numerical models can simulate the evolution of the mineralization and have provided insightful results for specific ore-forming processes 26,29 , but still rely on some simplifications. In particular, capabilities for full reactive-transport modeling including chemical speciation, pH and redox conditions as well as the role of ligand complexing for metal transport in the formation of high-temperature ore deposits are still under development.…”

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confidence: 99%

Hydrological controls on base metal precipitation and zoning at the porphyry-epithermal transition constrained by numerical modeling

Stoltnow

Weis

Korges

2023

Sci Rep

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Ore precipitation in porphyry copper systems is generally characterized by metal zoning (Cu–Mo to Zn–Pb–Ag), which is suggested to be variably related to solubility decreases during fluid cooling, fluid-rock interactions, partitioning during fluid phase separation and mixing with external fluids. Here, we present new advances of a numerical process model by considering published constraints on the temperature- and salinity-dependent solubility of Cu, Pb and Zn in the ore fluid. We quantitatively investigate the roles of vapor-brine separation, halite saturation, initial metal contents, fluid mixing and remobilization as first-order controls of the physical hydrology on ore formation. The results show that the magmatic vapor and brine phases ascend with different residence times but as miscible fluid mixtures, with salinity increases generating metal-undersaturated bulk fluids. The release rates of magmatic fluids affect the location of the thermohaline fronts, leading to contrasting mechanisms for ore precipitation: higher rates result in halite saturation without significant metal zoning, lower rates produce zoned ore shells due to mixing with meteoric water. Varying metal contents can affect the order of the final metal precipitation sequence. Redissolution of precipitated metals results in zoned ore shell patterns in more peripheral locations and also decouples halite saturation from ore precipitation.

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“…In contrast, homogenization by magma convection could produce fluids that chemically (e.g., salinity, metal contents) evolve with time according to different crystallization stages (Cline & Bodnar, 1991). For this study, we used a dry rhyolitic magma, but our newly developed coupled model can be extended by adding existing modeling capabilities for magmatic volatile release and incremental magma emplacement (Korges et al, 2020; Weis et al, 2012) to capture these processes.…”

Section: Discussionmentioning

confidence: 99%

Heat Transfer From Convecting Magma Reservoirs to Hydrothermal Fluid Flow Systems Constrained by Coupled Numerical Modeling

Andersen

Weis

2020

Geophysical Research Letters

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Magma flow, heat conduction, and hydrothermal fluid flow control the heat transfer through the upper crust. Magmatic-hydrothermal activity is essential for the utilization of geothermal energy, formation of ore deposits, and predictions of volcanic hazards, but the interplay between magmatic and hydrothermal processes is not well constrained due to the lack of adequate scientific tools. Simulation results from our novel coupled numerical model resolving both magma (Navier-Stokes) and hydrothermal (Darcy) flow quantify the influence of magma convection and rock permeability on energy transfer. Convection of a hot-dry rhyolitic magma has an accelerating effect of up to 15% on the cooling of the reservoir by enhancing the heat transfer toward the magma-hydrothermal interface. However, at high permeabilities and high brittle-ductile transition temperatures, magma flow can also have a secondary decelerating effect, because it prevents efficient permeability creation and entrainment of hydrothermal fluids at the edges of the magma reservoir. Plain Language Summary Magmatic bodies intruded into the Earth's crust at several kilometers depth provide a heat source that drives fluid circulation through permeable rocks. These hydrothermal systems lead to constant degassing of high-temperature fluids in volcanic systems during and between eruption events and can form geothermal resources and ore deposits. At low crystallinities, magma moves within the reservoir. Thus, heat transfer in magmatic-hydrothermal systems occurs by coupled processes of two distinct flow regimes-magma and hydrothermal fluid. Until now, numerical models have focused either on the magmatic or the hydrothermal system. We have developed a fully coupled model that can simulate both processes simultaneously and the interplay between them. We find that rock permeability and thereby the vigor of hydrothermal fluid flow are the primary control on the cooling rates of magmatic intrusions. Magma convection can accelerate this process by up to 15% by efficiently transporting heat toward the magma-hydrothermal interface, where it can be picked up by fluids and transported toward the Earth's surface. However, this process can be counteracted by a secondary deceleration effect that prevents fracturing at high temperatures and thus cooling down of the edges of the magma chamber by hydrothermal fluids.

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The role of incremental magma chamber growth on ore formation in porphyry copper systems

Cited by 29 publications

References 43 publications

From long-lived batholith construction to giant porphyry copper deposit formation: petrological and zircon chemical evolution of the Quellaveco District, Southern Peru

From long-lived batholith construction to giant porphyry copper deposit formation: petrological and zircon chemical evolution of the Quellaveco District, Southern Peru

Hydrological controls on base metal precipitation and zoning at the porphyry-epithermal transition constrained by numerical modeling

Heat Transfer From Convecting Magma Reservoirs to Hydrothermal Fluid Flow Systems Constrained by Coupled Numerical Modeling

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