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Magmas, ore deposits and geodynamic evolution at a convergent margin: the case of Ecuador

English title Magmas, ore deposits and geodynamic evolution at a convergent margin: the case of Ecuador
Applicant Chiaradia Massimo
Number 137663
Funding scheme Project funding
Research institution Département des sciences de la Terre Université de Genève
Institution of higher education University of Geneva - GE
Main discipline Geochemistry
Start/End 01.01.2012 - 31.12.2013
Approved amount 156'618.00
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Keywords (8)

magmatic processes; adakite-like; geochronology; radiogenic isotopes; subduction; Ecuador; Peru; porphyry systems

Lay Summary (English)

Lead
Lay summary
In the past years (SNF Projects N. 200021-109636 and 200020-117616, first year of the current project 200020-126896) we have investigated the link between changes in magma chemistry (in particular the development of adakite-like signatures) and geodynamic setting at convergent continental margins of Ecuador and Peru, and how these could influence the formation of porphyry-type deposits. The main results of our previous and current investigations can be summarized as follows: (i) in the investigated cases adakite-like rocks are formed by magmatic evolution at variably deep crustal levels and under hydrous conditions, favoring the stability of amphibole ± garnet but not that of plagioclase; (ii) porphyry-type deposits form in association with adakite-like rocks during a few Ma (~1-3 Ma) towards the end of a several Ma (~6-15 Ma) long transition from normal to adakite-like magmatism; (iii) increased compression with or without attending crustal thickening is held responsible to have caused a shift of the locus of magmatic evolution from shallow crustal levels (normal arc rocks) to deeper ones (adakite-like signatures); (iv) increased compression might be related to subduction of aseismic ridges and/or any other topographic high (e.g., oceanic plateau) which increase the coupling between subducting and overriding plates, although other changes at the subduction zone (e.g., subduction obliquity, plate relative velocity) may also play a role.
After having verified in the previous years the occurrence of such an “empirical” link between porphyry-type deposit and transition from normal to adakite-like signatures, in the current project (N. 200020-126896) and its extension we want to investigate in detail three processes which can potentially play a role in this connection: (1) longevity of magmatic reservoirs with adakite-like signatures; (2) temporal frequency of magmatic pulses in mineralized and non-mineralized magmatic systems with adakite-like signatures; (3) specialization of adakite-like magmas in terms of volatiles (S, Cl) and metals.
To do this we study both ancient mineralized systems (subproject A: PhD project of Mr. Cyril Chelle-Michou) and recent or active non-mineralized volcanic systems (subproject B: carried out by the applicant), both characterized by adakite-like signatures, using a range of state-of-the-art analytical tools (whole rock major and trace element geochemistry, whole rock isotope (Sr, Nd, Pb) geochemistry, mineral chemistry by microprobe and LA-ICP-MS, high-precision ID-TIMS and LA-ICP-MS U/Pb dating of zircons, Hf isotope geochemistry of zircons). The ancient mineralized system investigated is the Coroccohuayco magmatic system which displays a magmatic evolution through time (from about 42 to 35 Ma) characterized by a transition from normal to adakite-like rocks. Coroccohuayco belongs to the world-class Tintaya skarn and porphyry district and therefore is suitable to try to answer the above questions.
The recent to active volcanic systems investigated are the Quaternary adakite-like rocks of Ecuador. The advantage of studying the Quaternary volcanoes of Ecuador in the frame of this project is twofold: (i) well-constrained knowledge of the geodynamic setting; (ii) opportunity to work on fresh volcanic rocks and glasses on which study the behaviour of metals and volatiles under the adakitic regime. The combination of the information obtained on the young rocks with that obtained on the ancient mineralized system will be a powerful tool to elucidate the effective role of adakite-like magmas in the generation of porphyry-type deposits.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Copper enrichment in arc magmas controlled by overriding plate thickness
Chiaradia Massimo (2014), Copper enrichment in arc magmas controlled by overriding plate thickness, in Nature Geoscience, 7, 43-46.
How accurately can we date the duration of magmatic-hydrothermal events in porphyry systems?
Chiaradia M. Schaltegger U. Spikings R. Wotzlaw J.-F. Ovtcharova M. (2013), How accurately can we date the duration of magmatic-hydrothermal events in porphyry systems?, in Economic Geology, 108(4), 565-584.
Metallogenic features of Miocene porphyry Cu and porphyry-related mineral deposits in Ecuador revealed by Re-Os, Ar-40/Ar-39, and U-Pb geochronology
Schutte P, Chiaradia M, Barra F, Villagomez D, Beate B (2012), Metallogenic features of Miocene porphyry Cu and porphyry-related mineral deposits in Ecuador revealed by Re-Os, Ar-40/Ar-39, and U-Pb geochronology, in MINERALIUM DEPOSITA, 47(4), 383-410.
Why large porphyry Cu deposits like high Sr/Y magmas?
Chiaradia Massimo, Ulianov Alexey, Kouzmanov Kalin, Beate Bernardo (2012), Why large porphyry Cu deposits like high Sr/Y magmas?, in Scientific Reports, 2(685), 1-7.
Quaternary sanukitoid-like andesites generated by intracrustal processes (Chacana caldera complex, Ecuador): implications for Archean sanukitoids
Chiaradia Massimo, Müntener Othmar, Beate Bernardo, Quaternary sanukitoid-like andesites generated by intracrustal processes (Chacana caldera complex, Ecuador): implications for Archean sanukitoids, in Journal of Petrology, 1.

Collaboration

Group / person Country
Types of collaboration
Bernardo Beate, Escuela Politecnica Nacional, Quito, Ecuador Ecuador (South America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. François Bussy, University of Lausanne, Switzerland Switzerland (Europe)
- Research Infrastructure
Prof. Jaime D. Barnes, University of Texas United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. Othmar Müntener, University of Lausanne, Switzerland Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
SEG 2012 Conference Talk given at a conference The Eocene Coroccohuayco and Tintaya copper porphyry-skarn deposits, Peru: 5 Ma of favorable tectono-magmatic evolution 23.09.2012 Lima, Peru Chelle-Michou Cyril;
SEG 2012 Conference Individual talk Metallogeny in the Northern Andes of Ecuador 22.09.2012 Lima, Peru Chiaradia Massimo;
Gordon Conference on Geochemistry of Mineral Deposits Poster Evolution of the Coroccohuayco magmatic suite (Peru) revealed by LA-ICP-MS and CA-ID-TIMS zircon U-Pb geochronology 15.07.2012 Handover, NH, United States of America Chelle-Michou Cyril;
Goldschmidt Conference 2012 Talk given at a conference Zircon as a probe of oxygen fugacity: observations and limitations from natural samples 24.06.2012 Montreal, Canada Chelle-Michou Cyril;


Associated projects

Number Title Start Funding scheme
126896 Magmas, ore deposits and geodynamic evolution at a convergent margin: the case of Ecuador 01.01.2010 Project funding
177026 Re-equiping the noble gas laboratory to perform state of the art science, University of Geneva 01.03.2018 R'EQUIP
149147 Magmas, ore deposits and geodynamic evolution at convergent margins 01.02.2014 Project funding
126896 Magmas, ore deposits and geodynamic evolution at a convergent margin: the case of Ecuador 01.01.2010 Project funding
149147 Magmas, ore deposits and geodynamic evolution at convergent margins 01.02.2014 Project funding

Abstract

The present proposal is for a 2-year extension of the SNF project. N. 200020-126896 “Magmas, ore deposits and geodynamic evolution at a convergent margin: the case of Ecuador”. Funds are asked for a 2-year extension of the PhD student salary, fieldwork and attendance to conferences by the PhD student and the applicant, as well as for analytical work. The PhD student, Mr. Cyril Chelle-Michou, was engaged for this project from 1 January 2010.In the past years (SNF Projects N. 200021-109636 and 200020-117616, first year of the current project 200020-126896) we have investigated the link between changes in magma chemistry (in particular the development of adakite-like signatures) and geodynamic setting at convergent continental margins in Ecuador and Peru, and how these could influence the formation of porphyry-type deposits. The main results of our previous and current investigations can be summarized as follows: (i) in the investigated cases adakite-like rocks are formed by magmatic evolution at variably deep crustal levels and under hydrous conditions, favoring the stability of amphibole ± garnet but not that of plagioclase; (ii) porphyry-type deposits form in association with adakite-like rocks during a few Ma (~1-3 Ma) towards the end of a several Ma (~6-15 Ma) long transition from normal to adakite-like magmatism; (iii) increased compression with or without attending crustal thickening is held responsible to have caused a shift of the locus of magmatic evolution from shallow crustal levels (normal arc rocks) to deeper ones (adakite-like signatures); (iv) increased compression might be related to subduction of aseismic ridges and/or any other topographic high (e.g., oceanic plateau) which increase the coupling between subducting and overriding plates, although other changes at the subduction zone (e.g., subduction obliquity, plate relative velocity) may also play a role.After having verified in the previous years the occurrence of such an “empirical” link between porphyry-type deposit and transition from normal to adakite-like signatures, in the current project (N. 200020-126896) and its extension we want to investigate in detail three processes which can potentially play a role in this connection: (1) longevity of magmatic reservoirs with adakite-like signatures; (2) temporal frequency of magmatic pulses in mineralized and non-mineralized magmatic systems with adakite-like signatures; (3) specialization of adakite-like magmas in terms of volatiles (S, Cl) and metals.To do this we study both ancient mineralized systems (subproject A: PhD project of Mr. Cyril Chelle-Michou) and recent or active non-mineralized volcanic systems (subproject B: carried out by the applicant), both characterized by adakite-like signatures. The ancient mineralized system investigated is the Coroccohuayco magmatic system which displays a magmatic evolution through time (from about 42 to 35 Ma) characterized by a transition from normal to adakite-like rocks. Coroccohuayco belongs to the world-class Tintaya skarn and porphyry district and therefore is suitable to try to answer the above questions.The recent to active volcanic systems investigated are the Quaternary adakite-like rocks of Ecuador. The advantage of studying the Quaternary volcanoes of Ecuador in the frame of this project is twofold: (i) well-constrained knowledge of the geodynamic setting; (ii) opportunity to work on fresh volcanic rocks and glasses on which study the behaviour of metals and volatiles under the adakitic regime. The combination of the information obtained on the young rocks with that obtained on the ancient mineralized system will be a powerful tool to elucidate the effective role of adakite-like magmas in the generation of porphyry-type deposits.
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