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Tracing the invisible path of fluids in the crust with microscale oxygen isotope measurements in key metamorphic minerals

English title Tracing the invisible path of fluids in the crust with microscale oxygen isotope measurements in key metamorphic minerals
Applicant Rubatto Daniela
Number 166280
Funding scheme Project funding (Div. I-III)
Research institution Institut für Geologie Universität Bern
Institution of higher education University of Berne - BE
Main discipline Geochemistry
Start/End 01.04.2016 - 31.08.2020
Approved amount 833'393.00
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All Disciplines (3)

Discipline
Geochemistry
Mineralogy
Geochronology

Keywords (6)

metamorphic fluids; white mica ; accessory minerals ; subduction; garnet; oxygen isotopes

Lay Summary (Italian)

Lead
I fluidi ricchi in acqua hanno un ruolo critico durante i processi metamorfici nella crosta e la parte superiore del mantello terrestre. Essi influenzano direttamente processi fondamentali quali il trasporto degli elementi, la cinetica delle reazioni ed il trasferimento di calore. Comprendere i flussi, le sorgenti e l’interazione di tali fluidi con i minerali è dunque fondamentale per ricostruire questi processi geologici e la struttura del nostro pianeta. Questo progetto propone un approccio multidisciplinare per investigate l’interazione tra fluidi e minerali nella crosta terrestre.
Lay summary

L'obiettivo di questa ricerca è di sviluppare strumenti e conoscenza per la ricostruzione dei percorsi pressione-temperatura-tempo e fluidi in rocce metamorfiche. L’approccio proposto include analisi degli isotopi dell’ossigeno e modellizzazione termodinamica. Miriamo a stabilire e calibrare metodi robusti per l’analisi degli isotopi dell’ossigeno in alcuni minerali chiave usando la microsonda ionica, che permette accurate analisi alla microscala. Inoltre integreremo l'evoluzione degli isotopi dell’ossigeno nei pacchetti termodinamici comunemente usati per la modellazione delle rocce metamorfiche. Le metodologie sviluppate saranno poi testate su rocce naturali e combinati con l’analisi delle zonature chimiche e la geocronologia per ricostruire il passaggio ed il ruolo dei fluidi.

Questa ricerca permetterà di espandere l’uso degli isotopi dell’ossigeno come traccianti dei fluidi nella crosta terrestre a nuovi minerali e svariate situazioni geologiche. Questo lavoro si colloca all’interno del largo investimento tecnologico che la Svizzera ha fatto in microanalitica e assicurerà sviluppo di conoscenza avanzata per mantenere la ricerca svizzera all’avanguardia nel settore della geochimica.

Direct link to Lay Summary Last update: 29.03.2016

Responsible applicant and co-applicants

Employees

Associated projects

Number Title Start Funding scheme
177026 Re-equiping the noble gas laboratory to perform state of the art science, University of Geneva 01.03.2018 R'EQUIP
170722 A new state-of-the-art Laser Ablation ICP-MS facility with emphasis on mapping and technique development 01.01.2017 R'EQUIP
170738 New Ionpolisher for high-end surface preparation of composite materials 01.12.2016 R'EQUIP

Abstract

This project requests funds for establishing a new research group in geochemistry of metamorphic rocks with emphasis on oxygen isotopes at the microscale. The project involves a main investigator, a postdoctoral researcher and two PhD students. The aim is to develop tools and knowledge for reconstructing pressure-temperature-time-fluid paths in metamorphic terranes that underwent complex evolutions and where the role of fluids is crucial for element transport and reaction kinetics. Within the course of this project we will establish new protocols and standards for the analyses of oxygen isotopes by ion microprobe in key metamorphic minerals such as garnet, monazite and apatite. This methodology will also be expanded in an exciting novel direction (postdoctoral project) by investigating white mica: (i) its capacity to record and preserve oxygen isotope signatures over metamorphic stages and (ii) the possibility to use this common hydrous mineral, which is also a thermochronometer, to trace fluid signatures in crustal rocks. The proposed research project will integrate the evolution of oxygen isotopic signatures in metamorphic systems into thermodynamic packages (Perple_X and Theriak/Domino) that are commonly used for modeling metamorphic assemblages over changing pressure and temperature. Combination of modeling and measurements on natural samples will be crucial to identify open versus closed system behavior. The oxygen isotope analyses will be supported and combined with textural investigations at the microscale to identify metamorphic stages, major and with trace element analyses to characterize mineral zoning and interaction with fluids and, whenever possible, with geochronology of mineral zones to constrain the timing. This combined approach will ensure significant advances in microanalytical techniques and develop a new field of research that harvests the wealth of information on fluids and their evolution over time recorded in zoned minerals. The methodology will be tested on selected samples and applied to two field areas (PhD projects) that expose rocks recording subduction processes in both oceanic and continental crust and where evidence of significant fluid alteration and interaction exists.
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