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Origin and growth of Alpine fissure minerals: fluid-mineral interaction and implications for the Alpine metamorphism

English title Origin and growth of Alpine fissure minerals: fluid-mineral interaction and implications for the Alpine metamorphism
Applicant Vennemann Torsten
Number 143885
Funding scheme Project funding (Div. I-III)
Research institution Institut de Minéralogie et Géochimie Université de Lausanne
Institution of higher education University of Lausanne - LA
Main discipline Geochemistry
Start/End 01.10.2012 - 30.09.2015
Approved amount 206'472.00
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All Disciplines (3)

Discipline
Geochemistry
Mineralogy
Geology

Keywords (6)

Trace Elements; Chemical Composition; Oxygen; Thermometry; Isotopes; Mineralogy

Lay Summary (English)

Lead
Lay summary

This project is aimed at both complementing the existing knowledge on oxygen isotope fractionation and trace element incorporation in minerals formed at "low" temperatures in a natural context of Alpine-type veins and link the interpretation of mineral-mineral fractionations and zonation to the retrograde path of the Alpine regional metamorphism in the western Swiss Alps and the fluid flow active in the upper-crust during the Neogene. Late-Alpine extension veins will be investigated from the non-metamorphic diagenetic zone of the Molasse plateau to the high-grade epizone and mesozone of the Penninic Nappes following the Rhône valley. Veins containing datable minerals (muscovite, biotite, apatite, titanite, brookite, monazite,...) will be selected. Together with a detailed investigation of metamorphism in the wall rocks to the veins, this will permit P-T-t-x reconstructions for the late-Alpine metamorphism and add to the existing data for a better understanding of the regional Alpine metamorphism. In contrast to some previous studies, the approach focuses on choosing veins with coexisting minerals such as quartz, albite, chlorite, and orthoclase and to conduct parallel in-situ (ion-probe and laser-ablation) and some bulk analysis of the isotope and trace element compositions of vein and matrix wall rock minerals so as to characterize their conditions of formation within the metamorphic context. For quartz, different habitus of different generations (5-10) found in various geological contexts will also be selected for trace element and isotopic measurements. Albite crystals are also widespread in the Alpine fissures of the western Alps and their suitability for these types of studies has already been demonstrated with preliminary work on these veins. Both lamellar and macromosaic types of quartz will be analysed. The goal is to characterize a possible evolution of the fluid-mineral equilibrium from the perturbed and fast growth of "skeletal" Bambauer's quartz to the unperturbed and slow growth environment of the "normal" Friedlander's quartz found in the external crystalline massifs. Factors controlling the habitus and crystallization mechanisms of quartz will be evaluated.  Part of the study will also be dedicated to the mineral inclusions in quartz as indicators of metamorphism relative to the minerals in the host rocks. The analytical approach concentrates on macro- and microscopic analyses, cathodoluminescence, studies of fluid inclusion compositions and microthermometric studies thereof.


Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Name Institute

Collaboration

Group / person Country
Types of collaboration
Baumgartner, Lukas Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Putlitz, Benita Switzerland (Europe)
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
American Geophysical Union Annual Meeting 2014 Poster SIMS investigations on growth and sector zoning in natural hydrothermal quartz: isotopic and trace element analyses 14.12.2014 San Francisco, United States of America Vennemann Torsten; May Eric;
European Geoscience Union Annual Meeting 2014 Poster Isotopic investigations on albite-quartz alpine-type extensive veins from Western Swiss Alps 27.04.2014 Vienna, Austria May Eric;
Swiss Geoscience Meeting 2013 Poster Geochemical study of mineral paragenesis from Alpine-type veins in the Western Swiss Alps 15.11.2013 Lausanne, Switzerland Vennemann Torsten; Meisser Nicolas; May Eric;


Knowledge transfer events

Active participation

Title Type of contribution Date Place Persons involved
Alpine vein mineralogy - field trip for Pangea, student organisation at Lausanne 12.09.2014 Valais, Switzerland Meisser Nicolas; May Eric;


Associated projects

Number Title Start Funding scheme
116550 Experimental determination of exchange mechanism and hydrogen isotope fractionation between chlorite and water 01.04.2007 Project funding (Div. I-III)
140498 Chlorite as a key mineral for geothermometry: Empirical verifications of thermodynamic models for Fe-Mg aluminous chlorite and calibration of the oxygen isotope fractionation between chlorite, quartz and calcite 01.05.2012 Project funding (Div. I-III)
164032 CLUMPING LAUSANNE: A REQUEST FOR A REGIONAL FACILITY TO MEASURE CLUMPING IN CARBONATES 01.01.2016 R'EQUIP
111757 Controls on mineral-fluid oxygen isotope fractionations in geologic systems 01.04.2006 Project funding (Div. I-III)
124787 Faults and fluids: deep penetration of meteoric waters into the Alps during their exhumation 01.05.2009 Project funding (Div. I-III)

Abstract

Measurements of stable isotope and trace element content in minerals are widely used methods that allow for a better understanding of the conditions of formation of minerals in a range of different geological environments. In this context oxygen isotope equilibrium between minerals and fluids has been demonstrated on the basis of experimental, theoretical, and empirical calibrations describing isotopic fractionation in high-temperature environments. For many "low-temperature" geological processes (below about 400°C), however, the establishment of an equilibrium is still controversial. Slow diffusivity and isotopic and chemical exchange rates as well as possible surface effects during mineral precipitation at relatively low temperatures are complicating factors in low-temperature environments. The funding requested in this proposal is aimed at both complementing the existing knowledge on oxygen isotope fractionation and trace element incorporation in minerals formed at "low" temperatures in a natural context of Alpine-type veins and link the interpretation of mineral-mineral fractionations and zonation to the retrograde path of the Alpine regional metamorphism in the western Swiss Alps and the fluid flow active in the upper-crust during the Neogene. Late-Alpine extension veins will be investigated from the non-metamorphic diagenetic zone of the Molasse plateau to the high-grade epizone and mesozone of the Penninic Nappes following the Rhône valley. Veins containing datable minerals (muscovite, biotite, apatite, titanite, brookite, monazite,...) will be selected. Together with a detailed investigation of metamorphism in the wall rocks to the veins, this will permit P-T-t-x reconstructions for the late-Alpine metamorphism and add to the existing data for a better understanding of the regional Alpine metamorphism. In contrast to some previous studies, the approach focuses on choosing veins with coexisting minerals such as quartz, albite, chlorite, and orthoclase and to conduct parallel in-situ (ion-probe and laser-ablation) and some bulk analysis of the isotope and trace element compositions of vein and matrix wall rock minerals so as to characterize their conditions of formation within the metamorphic context. For quartz, different habitus of different generations (5-10) found in various geological contexts will also be selected for trace element and isotopic measurements. Albite crystals are also widespread in the Alpine fissures of the western Alps and their suitability for these types of studies has already been demonstrated with preliminary work on these veins. Both lamellar and macromosaic types of quartz will be analysed. The goal is to characterize a possible evolution of the fluid-mineral equilibrium from the perturbed and fast growth of "skeletal" Bambauer's quartz to the unperturbed and slow growth environment of the "normal" Friedlander's quartz found in the external crystalline massifs. Factors controlling the habitus and crystallization mechanisms of quartz will be evaluated. Part of the study will also be dedicated to the mineral inclusions in quartz as indicators of metamorphism relative to the minerals in the host rocks. The analytical approach concentrates on macro- and microscopic analyses, cathodoluminescence, studies of fluid inclusion compositions and microthermometric studies thereof.
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