Zircon petrochronology reveals the temporal link between porphyry systems and the magmatic evolution of their hidden plutonic roots (the Eocene Coroccohuayco deposit, Peru)

Chelle-Michou, Cyril; Chiaradia, Massimo; Ovtcharova, Maria; Ulianov, Alexey; Wotzlaw, Jörn‐Frederik

doi:10.1016/j.lithos.2014.03.017

Cited by 127 publications

(71 citation statements)

References 72 publications

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“…These observations suggest that the pressure and temperature estimates using the empirical formulation of Ridolfi and Renzulli (2012) represent reasonable values for the porphyries. The increase in oxygen fugacity from the gabbrodiorite complex to the porphyries is supported by a mineralogical change of the Ti phase from ilmenite to titanite and by the increasing zircon Ce anomaly (Chelle-Michou et al 2014, 2015a. Finally, the estimated melt H 2 O concentration is consistent with the facts that basic to silicic arc magmas are hydrous and that magmatic water saturation at 250-100 MPa is around 6-4 wt% (e.g., Baker and Alletti 2012).…”

Section: Amphibolesupporting

confidence: 73%

“…This calc-alkaline batholith represents the plutonic root of the subduction-related Eocene magmatic arc and is emerging as an important Cu-Au metallogenic province. Magmatism and hydrothermal activity at Coroccohuayco is polyphased, and lasted from 41 to 35 Ma (Chelle-Michou et al 2014, 2015b. The geochemical and petrological features of the Coroccohuayco magmatic suite have previously been described in Chelle-Michou et al (2015a) and are summarized below.…”

Section: Geological Backgroundmentioning

confidence: 97%

“…Geochemical modeling has suggested Amp amphibole, ap apatite, bio biotite, mt magnetite, pl plagioclase, qtz quartz, ttn titanite that the chemistry of the porphyries results from a longlived evolution within a deep crustal hot zone dominated by crystal fractionation, followed by crustal assimilation in the mid to upper crust. High-precision U-Pb zircon dating of the rhyodacite revealed that it resulted from the remelting of a proto-pluton emplaced at 36.1 Ma (Chelle-Michou et al 2014). It has been inferred that this melting event was contemporaneous with the emplacement of the porphyries and was triggered by the emplacement and degassing of a large pluton in the upper crust (Chelle-Michou et al 2014, 2015a.…”

Section: Geological Backgroundmentioning

confidence: 99%

“…High-precision U-Pb zircon dating of the rhyodacite revealed that it resulted from the remelting of a proto-pluton emplaced at 36.1 Ma (Chelle-Michou et al 2014). It has been inferred that this melting event was contemporaneous with the emplacement of the porphyries and was triggered by the emplacement and degassing of a large pluton in the upper crust (Chelle-Michou et al 2014, 2015a.…”

Section: Geological Backgroundmentioning

confidence: 99%

“…This is consistent with previous results showing that this rock was emplaced as a result of proto-pluton remelting under near-zircon saturated conditions (this rock contains mostly antecrystic zircon and very little autocrystic ones; Chelle-Michou et al 2014). Chelle-Michou et al (2014) proposed that this remelting event was the consequence of the establishment of a longlived and large thermal anomaly in the crust culminating with the emplacement of a large volume dacitic magma that sourced the ore-forming fluids of the Coroccohuayco deposit. Under these conditions, melting of a calc-alkaline proto-pluton or of the surrounding crust (sediments, volcanic rocks, older pluton) would have produced a peraluminous interstitial liquid (A/CNK > 1, where A/CNK is the Al 2 O 3 / [CaO + Na 2 O + K 2 O] molar ratio) (Patiño Douce 1997).…”

Section: Apatitementioning

confidence: 99%

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Amphibole and apatite insights into the evolution and mass balance of Cl and S in magmas associated with porphyry copper deposits

Chelle-Michou

Chiaradia

2017

Contrib Mineral Petrol

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Chlorine and sulfur are of paramount importance for supporting the transport and deposition of ore metals at magmatichydrothermal systems such as the Coroccohuayco Fe-Cu-Au porphyry-skarn deposit, Peru. Here, we used recent partitioning models to determine the Cl and S concentration of the melts from the Coroccohuayco magmatic suite using apatite and amphibole chemical analyses. The pre-mineralization gabbrodiorite complex hosts S-poor apatite, while the syn-and post-ore dacitic porphyries host S-rich apatite. Our apatite data on the Coroccohuayco magmatic suite are consistent with an increasing oxygen fugacity (from the gabbrodiorite complex to the porphyries) causing the dominant sulfur species to shift from S 2− to S 6+ at upper crustal pressure where the magmas were emplaced. We suggest that this change in sulfur speciation could have favored S degassing, rather than its sequestration in magmatic sulfides. Using available partitioning models for apatite from the porphyries, pre-degassing S melt concentration was 20-200 ppm. Estimates of absolute magmatic Cl concentrations using amphibole and apatite gave highly contrasting results. Cl melt concentrations obtained from apatite (0.60 wt% for the gabbrodiorite complex; 0.2-0.3 wt% for the porphyries) seems much more reasonable than those obtained from amphibole which are very low (0.37 wt% for the gabbrodiorite complex; 0.10 wt% for the porphyries). In turn, relative variations of the Cl melt concentrations obtained from amphibole during magma cooling are compatible with previous petrological constraints on the Coroccohuayco magmatic suite. This confirms that the gabbrodioritic magma was initially fluid undersaturated upon emplacement, and that magmatic fluid exsolution of the gabbrodiorite and the pluton rooting the porphyry stocks and dikes were emplaced and degassed at 100-200 MPa. Finally, mass balance constraints on S, Cu and Cl were used to estimate the minimum volume of magma required to form the Coroccohuayco deposit. These three estimates are remarkably consistent among each other (ca. 100 km 3 ) and suggest that the Cl melt concentration is at least as critical as that of Cu and S to form an economic mineralization.

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Section: Amphibolesupporting

confidence: 73%

Section: Geological Backgroundmentioning

confidence: 97%

Section: Geological Backgroundmentioning

confidence: 99%

Section: Geological Backgroundmentioning

confidence: 99%

Section: Apatitementioning

confidence: 99%

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Amphibole and apatite insights into the evolution and mass balance of Cl and S in magmas associated with porphyry copper deposits

Chelle-Michou

Chiaradia

2017

Contrib Mineral Petrol

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Radiometric Dating Applied to Ore Deposits: Theory and Methods

Chiaradia

2023

Isotopes in Economic Geology, Metallogenesis and Exploration

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Metallic ore deposits have contributed to the development of the human society since pre-historic times and nowadays are one of the pillars of unprecedented technological developments. In order to understand how metallic ore deposits form and thus construct genetic models that may serve as exploration guides, determining the age of an ore deposit is one of the most important pieces of information needed. More recently it has also become evident that determining the temporal duration of mineralizing events can offer valuable information on how certain deposits form and thus improve genetic models. Radiometric dating of ore minerals or of other minerals that are demonstrably associated in space and time with mineralization is the most accurate and precise tool to date an ore deposit. This Introductory Chapter summarizes basic concepts on why ore deposit dating is important and how this can be achieved through different methods. It illustrates basic differences among different methods and serves as an introduction to the more detailed descriptions of specific dating methods presented in the following Chapters.

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U–Pb Dating of Mineral Deposits: From Age Constraints to Ore-Forming Processes

Chelle-Michou

Schaltegger

2023

Isotopes in Economic Geology, Metallogenesis and Exploration

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The timing and duration of ore-forming processes are amongst the key parameters required in the study of mineral systems. After more than a century of technical developments, innovations and investigation, the U–Pb system arguably is the most mature radioisotopic system in our possession to conduct absolute dating of a wide range of minerals across geological environments and metallogenic processes. Here, we review the basics of U–Pb geochronology, the key historic developments of the method, and the most commonly used analytical techniques (including data reduction, Pb-correction, uncertainty propagation and data presentation) and minerals while pointing out their respective advantages, weaknesses and potential pitfalls. We also highlight critical aspects that need to be considered when interpreting a date into the age of a geological process (including field and petrographic constraints, open-system behavior, handling and interpretation of uncertainties). While U–Pb geochronology is strongly biased toward zircon dating, we strive to highlight the great diversity of minerals amenable to U–Pb dating (more than 16 mineral species) in the context of mineral systems, and the variety of geological events they can potentially date (magmatism, hydrothermal activity, ore-formation, cooling, etc.). Finally, through two case studies we show (1) how multi-mineral geochronological studies have been used to bracket and decipher the age of multiple geological events associated with the world-class Witwatersrand gold province, and (2) how rather than the absolute age, the duration and rate of the mineralizing event at porphyry copper deposits opens new avenues to understand ore-forming processes and the main controls on the size of such deposits. The improving precision, accuracy and spatial resolution of analyses in tandem with high-quality field and petrographic observations, numerical modelling and geochemical data, will continue to challenge paradigms of ore-forming processes and contribute significant breakthroughs in ore deposit research and potentially to the development of new exploration tools.

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Zircon petrochronology reveals the temporal link between porphyry systems and the magmatic evolution of their hidden plutonic roots (the Eocene Coroccohuayco deposit, Peru)

Cited by 127 publications

References 72 publications

Amphibole and apatite insights into the evolution and mass balance of Cl and S in magmas associated with porphyry copper deposits

Amphibole and apatite insights into the evolution and mass balance of Cl and S in magmas associated with porphyry copper deposits

Radiometric Dating Applied to Ore Deposits: Theory and Methods

U–Pb Dating of Mineral Deposits: From Age Constraints to Ore-Forming Processes

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