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A subduction factory revealed: The Famatinian arc section, Argentina

English title A subduction factory revealed: The Famatinian arc section, Argentina
Applicant Bachmann Olivier
Number 173428
Funding scheme Bilateral programmes
Research institution Institut für Geochemie und Petrologie ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Geochemistry
Start/End 01.11.2017 - 31.10.2020
Approved amount 206'990.00
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All Disciplines (2)

Discipline
Geochemistry
Geology

Keywords (4)

Silicic magma; Magmatic differentiation; Plutonic/volcanic link; Crustal growth

Lay Summary (French)

Lead
Les zones de subduction (marges convergentes) sont des point clefs de notre planète, pour les raisons suivantes : (1) ce sont de véritables fabriques de croûte continentale, menant à la distillation de roches peu denses qui « flottent » à la surface du manteau terrestre ; (2) elles produisent un grandes partie des ressources minières d’importance stratégique pour notre société, (3) elles concentrent certains des plus dangereux phénomènes naturels qui secouent notre croûte continentale, tels les tremblements de terres et les grandes éruptions volcaniques. Mieux comprendre ces zones de subduction est donc un des buts principaux des géosciences.
Lay summary

Notre principal objectif est de contribuer à une meilleure compréhension des processus magmatiques ayant lieu en zones de subduction. Plus précisément, nous souhaitons étudier les roches volcaniques (émises à la surface de la terre) et plutoniques (cristallisant en profondeur dans la croûte terrestre) de l’arc Famatinien (Argentine), d’âge ordovicien (~470 Ma) afin d’y (i) établir une chronologie précise de la mise en place des magmas en utilisant les échantillons ramenés du terrain, et (ii) produire une base de données géochimique et pétrologique permettant d’interpréter les conditions de formation des magmas au cours du temps et à différentes profondeurs. Nous comparerons ensuite ces résultats à des simulations numériques de mise en place des magmas dans la croûte afin de mieux cerner les processus physiques contrôlant la croissance crustale, le dégazage des magmas, et le lien entre plutons et volcans.

Contexte scientifique et social du projet de recherche

Notre travail générera des informations inédites et essentielles quant aux processus actifs dans les zones de subduction. Ces informations géochimiques et géochronologiques sur les roches de l’arc Famatinien, couplé aux simulations numériques, pourront être comparées à d’autres zones de subduction exhumées, ainsi qu’aux zones de subduction actuelles, et permettront de mieux contraindre les phénomènes uniques prenant place au cœur de ces zones de convergence de plaques tectoniques.

 

Direct link to Lay Summary Last update: 19.05.2017

Responsible applicant and co-applicants

Employees

Name Institute

Collaboration

Group / person Country
Types of collaboration
Dr. Jörn Wotzlaw/ETHZ Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Dr. Matthieu Galvez/ETHZ Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Dr. Marcel Guillong/ETHZ Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
Dr. Ozge Karakas/ETHZ Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Axel Schmitt / Uni Heidelberg Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Prof. James Connolly / ETHZ Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Giuliano Camilletti / Universidad de Rio Cuarto Argentina (South America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Hutton Conference Talk given at a conference Timescales and processes within transcrustal magmatic systems 08.09.2019 Nanjing, China Cornet Julien; Bachmann Olivier;
Granite School Poster Characterizing an arc magmatic column: Insights from zircon geochemistry and high precision geochronology of the Famatinian arc, Argentina 08.07.2019 Roscoff, France Cornet Julien; Otamendi Juan; Bachmann Olivier;
Granite School Talk given at a conference Granites and yet more granites seventy(+) years on 08.07.2019 Roscoff, France Cornet Julien; Bachmann Olivier;


Communication with the public

Communication Title Media Place Year
Talks/events/exhibitions Supervulkane; Eine Bedrohung für die Menschheit German-speaking Switzerland 2019

Awards

Title Year
Joan Simpson Medal and AGU Fellow 2018

Associated projects

Number Title Start Funding scheme
178928 Dynamics of magma reservoirs in the earth’s crust; focusing on the role of volatile elements 01.04.2018 Project funding (Div. I-III)
165501 Towards a quantitative understanding of caldera-forming events 01.04.2016 Project funding (Div. I-III)

Abstract

The primary objective of this project is to investigate the P-T conditions and pathways along which the magmas evolve while they ascend from the deep crustal levels to feed the upper crustal batholiths and erupt as volcanic successions. We propose a multidisciplinary study combining field mapping, petrography, mineral chemistry (phase-forming and trace elements), whole rock (element and isotopic) geochemistry, geochronology, and thermal modeling in the central segment of the Famatinian arc to test the hypothesis that the Ordovician arc crust exposes from the deep-seated plutonic levels throughout the upper-crustal batholiths to the volcano-sedimentary succession. The central segment of the Famatinian arc (between 28 - 32º S) is a superb natural example to investigate the generation of an arc crustal column because along-strike changes in the degree of exhumation allow us to observe from the lower crust to the Ordovician paleo-surface (see figure 1). The exposure of co-magmatic and coeval lower- to mid-crustal plutonic roots, sub-volcanic shallow systems and volcanic deposits provides a unique opportunity to assess the geochemical relationship between magmas, which have crystallized at depth in the crust and those which have ascended to reach the surface. The major questions that will be addressed are: 1-What are the compositions of magmas crossing the mantle - crustal boundary zone, and what are the processes occurring in the deep crust during the development of arc magmatic columns?2-What are the processes controlling igneous differentiation in an arc crust, in particular related to the formation of intermediate magmas, fueling the scientific debate about the rate and mechanism of continental growth at convergent margins?3-What are the dominant links between volcanic and plutonic lithologies in the Famatinian arc and what control their respective volumes and compositions?This project will contribute to society in several important ways, as the “subduction factory” remains a major topic in Geosciences for several reasons: 1) they contain the largest ore deposits; 2) they generate most of the volcanic hazards on our planet; and 3) they appear to be the engine of continental crustal construction through the geologic history of the Earth. The research involves the collaboration of researchers from Switzerland (ETHZ) and Argentina (Universidad Nacional de Río Cuarto). It will involve postdoctoral students, graduate and undergraduate students in carrying out the research plans. This research will greatly strengthen bi-national collaboration between scientists from both countries.
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