Stochastic modelling of deep magmatic controls on porphyry copper deposit endowment

Chiaradia, Massimo; Caricchi, Luca

doi:10.1038/srep44523

Cited by 140 publications

(141 citation statements)

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“…Various Miocene large Cu-Mo±Au porphyry deposits (e.g., Junin/Llurimagua Cu-Mo deposit and the Cascabel thickness ranging from 50 to 70 km (Feininger andSeguin, 1983, Guillier et al, 2001). Such features are similar to those of magmatic systems typically associated with large porphyry Cu deposits (Loucks, 2014, Chiaradia andCaricchi, 2017) and the temporal and spatial proximity of Miocene deposits to the Quaternary arc rocks investigated lend support to the possibility that processes leading to the formation of porphyry type deposits under 370 the Quaternary arc of Ecuador could be currently ongoing. Therefore, the Quaternary arc rocks of Ecuador can be used as a proxy of a potentially fertile typical Andean subduction-related magmatic environment.…”

Section: Comparison With Ecuadorsupporting

confidence: 59%

Magmatic sulphides in high-K calc-alkaline to shoshonitic and alkaline rocks

Georgatou

Chiaradia

2019

Preprint

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Abstract. We investigate in both mineralised and barren systems the occurrence and chemistry of magmatic sulphides and their chalcophile metal cargo behaviour during evolution of compositionally different magmas in diverse geodynamic settings. The investigated areas are: (a) the Miocene Konya magmatic province (hosting the Doganbey Cu-Mo and Inlice Au-epithermal deposits) (Post-Subduction) and (b) the Miocene Usak basin (Elmadag, Itecektepe and Beydagi volcanoes, the latter associated with the Kisladag Au porphyry) in Western Turkey (Post-Subduction). For comparison we also investigate (c) the barren Plio-Quaternary Kula volcanic field, west of Usak (Intraplate) and finally we discuss and compare all the above areas with the already studied (d) Quaternary Ecuadorian volcanic arc (host to the Miocene Llurimagua Cu-Mo and Cascabel Cu-Au porphyry deposits) (Subduction). The volcanism of the studied areas displays a wide range of SiO2 spanning from basalts to andesites/dacites and from high K-calc-alkaline to shoshonitic series. Multiphase magmatic sulphides occur in different amounts in all investigated areas and based on textural and compositional differences, they can be classified in different types, which crystallised at different times (early versus late saturation). A decrease in the sulphide Ni/Cu (proxy for mss-monosulphide solid solution/iss-intermediate solid solution) ratio is noted with magmatic evolution. Starting with an early stage, saturating Ni-richer/Cu-poorer sulphides hosted by early crystallising minerals e.g. olivine/pyroxene, leading up to a later stage, producing Cu-richer sulphides hosted by magnetite. The most common sulphide type resulting from an early saturating stage is composed of a Cu-poor/Ni-rich (pyrrhotite/mss) and one/two Cu-rich (cubanite, chalcopyrite/iss) phases making up 84 and 16 area % of the sulphide, respectively. Our results suggest that independently of the magma composition, geodynamic setting and whether or not the system has generated an ore deposit on the surface, sulphide saturation occurred in variable degrees in all studied areas and magmatic systems and is characterised by a similar initial metal content of the magmas. However not all studied areas present all sulphide types and the sulphide composition is dependent on the nature of the host mineral. In particular sulphides, resulting from the late stage, consisting of Cu-rich phases (chalcopyrite ,bornite, digenite/iss) are hosted exclusively by magnetite and are found only in magmatic provinces associated with porphyry Cu (Konya and Ecuador) and porphyry Au (Beydagi) deposits.

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Section: Comparison With Ecuadorsupporting

confidence: 59%

Magmatic sulphides in high-K calc-alkaline to shoshonitic and alkaline rocks

Georgatou

Chiaradia

2019

Preprint

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“…During extensive fractionation of hydrous magmas in the lower crust, amphibole (±garnet) is stabilized in the fractionating assemblage and plagioclase is suppressed (Müntener et al, 2001), resulting in melts with elevated Sr, an absence of strong negative Eu anomalies (both elements being compatible in plagioclase), and depleted Y (compatible in amphibole and garnet). Such magma evolution is promoted in strongly compressional, thickened arc crust and is commonly associated with porphyry Cu ore deposits because impeded magma ascent from the lower crust facilitates volatile accumulation and enrichment in ore-forming components (Chiaradia, 2015;Chiaradia and Caricchi, 2017). The high Sr/Y values that result can be used to provide insights into arc magma evolution (Macpherson et al, 2006;Rodriguez et al, 2007), evaluate whether a magmatic system has the potential to form a porphyry-related ore deposit in exploration (i.e., is "metallogenically fertile"; Richards, 2011;Loucks, 2014) and track crustal thickness (Chapman et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Multi-stage arc magma evolution recorded by apatite in volcanic rocks

Nathwani

Loader

Wilkinson

et al. 2020

Geology

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Protracted magma storage in the deep crust is a key stage in the formation of evolved, hydrous arc magmas that can result in explosive volcanism and the formation of economically valuable magmatic-hydrothermal ore deposits. High magmatic water content in the deep crust results in extensive amphibole ± garnet fractionation and the suppression of plagioclase crystallization as recorded by elevated Sr/Y ratios and high Eu (high Eu/Eu*) in the melt. Here, we use a novel approach to track the petrogenesis of arc magmas using apatite trace element chemistry in volcanic formations from the Cenozoic arc of central Chile. These rocks formed in a magmatic cycle that culminated in high-Sr/Y magmatism and porphyry ore deposit formation in the Miocene. We use Sr/Y, Eu/Eu*, and Mg in apatite to track discrete stages of arc magma evolution. We apply fractional crystallization modeling to show that early-crystallizing apatite can inherit a high-Sr/Y and high-Eu/Eu* melt chemistry signature that is predetermined by amphibole-dominated fractional crystallization in the lower crust. Our modeling shows that crystallization of the in situ host-rock mineral assemblage in the shallow crust causes competition for trace elements in the melt that leads to apatite compositions diverging from bulk-magma chemistry. Understanding this decoupling behavior is important for the use of apatite as an indicator of metallogenic fertility in arcs and for interpretation of provenance in detrital studies.

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“…Recent precise geochronological studies of porphyry deposits worldwide have indicated that deposits may form within tens of thousands of years (e.g., Henry et al, 1997;Shinohara and Hedenquist, 1997;Pollard et al, 2005;von Quadt et al, 2011;Chiaradia et al, 2013;Buret et al, 2016Buret et al, , 2017 or several million years (e.g., Ballard et al, 2001;Maksaev et al, 2006;Harris et al, 2008;Sillitoe and Mortensen, 2010;Barra et al, 2013;Deckart et al, 2013, 2014, andreferences therein;Leng et al, 2013). These longlived magmatic-hydrothermal events are typically attributed to episodic buildup and evolution of the underlying more voluminous pluton that feeds the upper crustal porphyritic intrusive complex (e.g., Sillitoe, 2010;Sillitoe and Mortensen, 2010;Chelle-Michou et al, 2014;Chiaradia and Caricchi, 2017;Leng et al, 2018).…”

Section: Formation and Duration Of The Pulang Porphyry Systemmentioning

confidence: 99%

Quantifying Exhumation at the Giant Pulang Porphyry Cu-Au Deposit Using U-Pb-He Dating

et al. 2018

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The Triassic Pulang porphyry Cu-Au deposit, located in the South Yidun terrane, is the oldest and one of the largest porphyry deposits in the southeastern Tibetan Plateau. The mineralization occurs mostly in the potassic alteration zone of the Pulang intrusive complex. U-Pb-He triple dating, namely apatite (U-Th)/He, zircon U-Pb, and zircon (U-Th)/He dating, together with inverse thermal modeling, reveals that the Pulang complex was emplaced at a paleodepth of ~5.0 to 6.5 km at 215 ± 2 Ma. The deep-level emplacement of the complex, coupled with the episodic replenishment of the magma chamber, gave rise to the establishment of a prolonged magmatic-hydrothermal system at Pulang. Although a range of single-grain zircon and apatite (U-Th)/He ages were obtained on each sample, the weighted mean zircon and apatite (U-Th)/He ages vary systematically with elevation, defining a multistage cooling/denudation history at Pulang. Specifically, three phases of cooling were recognized from inverse thermal modeling, including rapid cooling (80°-120°C/m.y.) in the Late Triassic, moderate cooling (3°-5°C/m.y.) from the Late Triassic to Early Cretaceous, and a protracted slow cooling period (<1°C/m.y.) from the Early Cretaceous to the present day. The first phase of cooling can be mainly attributed to magmatic cooling, whereas the later two phases of cooling were predominantly controlled by uplift and denudation processes. Moreover, the remarkable decrease in the cooling rate from the second to the third phase can be linked to a decreasing erosion rate during the third phase, supported by age-elevation relationships. Overall, our results indicate that the Pulang complex experienced two stages of exhumation at 33 to 45 m/m.y. and 5 to 17 m/m.y. Based on these data, we estimate that approximately 558-to 1,099-m thickness of materials have been removed from the Pulang complex during uplift and erosion, including a large volume of ore. The long time span (>50 m.y.) of extremely slow cooling and erosion at Pulang could be related to the formation and preservation of a peneplain on the southeastern Tibetan Plateau since the Late Cretaceous. A relict peneplain thus signifies a favorable tectonic environment for the preservation of ancient porphyry systems worldwide.

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Stochastic modelling of deep magmatic controls on porphyry copper deposit endowment

Cited by 140 publications

References 43 publications

Magmatic sulphides in high-K calc-alkaline to shoshonitic and alkaline rocks

Magmatic sulphides in high-K calc-alkaline to shoshonitic and alkaline rocks

Multi-stage arc magma evolution recorded by apatite in volcanic rocks

Quantifying Exhumation at the Giant Pulang Porphyry Cu-Au Deposit Using U-Pb-He Dating

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