Project

Back to overview

Nucleation and Crystal Growth in Metamorphic Environments: Integrated Geochemical and X-Ray Tomography Study of Bündnerschiefers of the Zermatt-Saas Zone, European Alps.

English title Nucleation and Crystal Growth in Metamorphic Environments: Integrated Geochemical and X-Ray Tomography Study of Bündnerschiefers of the Zermatt-Saas Zone, European Alps.
Applicant Baumgartner Lukas P.
Number 125261
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 Mineralogy
Start/End 01.04.2009 - 31.08.2012
Approved amount 207'110.00
Show all

Keywords (12)

growth kinetics; age dating; metamorphism; petrology; Alps; contact; thermal models; deformation; thermometry; barometry; trace element; EBSD

Lay Summary (English)

Lead
Lay summary
The research is part of the ProDoc initiative "Adamello 4D". The overall project strives to develop insights into the 4D evolution - that is 3 spatial coordinates and the temporal dimension -of the Adamello batholith. The Adamello is the largest intrusive complex exposed in the Alps today. This research project is charged to compile the existing metamorphic and structural data, and to complement the data set with new structural, metamorphic, mineralogical and petrological data to obtain a) a batholith scale thermal model and b) detailed, e.g. small scale thermo-mechanical models for the dynamic evolution of the contact aureole. It consists of two sub-projects, each liked to a PhD project.Project A) will study in detail the metamorphic history of the North-Western and North to Central Eastern contacts, where pre-Hercynian basement rocks are in contact with the intrusives of the batholith. Project B) will focus on the silicico-clastic sedimentary sequences of the Permo-Triassic in contact with the batholith in the south. Pelitic and semi-pelitic units were selected for this study, since they permit the best possible thermal estimates to be obtained. The proposed work will complement previous work (e.g. Stipp et al., 2002; Stipp et al, 2004, and references therein), which showed that syn- and post contact metamorphic deformation did occur along the Tonale line. The metamorphic paragenesis (including sillimanite, garnet, biotite and cordierite) are well suited for thermo-barometry using standard exchange thermometers and barometers. These will be complemented by the use of newly calibrated trace element exchange thermometers and stable isotope thermometry. Finally detailed deformation studies using texture analysis (field, EBSD, microscopy) will allow us to assess intensity and relative timing of deformation during emplacement of the batholith.The results will be used to obtain thermo-mechanical models for the emplacement of the intrusion(s) and the time-temperature evolution of the thermal aureole in collaboration with the other ProDoc projects.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Stable isotope composition of minerals of minerals during net transfer reactions in a contact aureole: Wollastonite growth at the northern Hunter Mountain Batholith (Death Valley National Park, USA)
Skora Susanne, Baumgartner Lukas P., Vennemann Torsten (2012), Stable isotope composition of minerals of minerals during net transfer reactions in a contact aureole: Wollastonite growth at the northern Hunter Mountain Batholith (Death Valley National Park, USA), in Chemical Geology, 289, 197-209.

Collaboration

Group / person Country
Types of collaboration
Dr. Tom Lapen/ University of Texas, Huston United States of America (North America)
- Publication
Dr. Clark Johnson/ University of Wisconsin, Madison United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Australian National University, Canberra Australia (Oceania)
- Publication
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
International Geological Congress 05.08.2012 Brisbane, Australia
AGU Fall Meeting 2011 05.12.2011 San Francisco, USA


Associated projects

Number Title Start Funding scheme
111868 Nucleation and Crystal Growth in Metamorphic Environments: An Integrated geochemical and X-Ray Tomography Study 01.04.2006 Project funding (Div. I-III)

Abstract

1.AbstractMineral assemblages contain not only information on their pressure, temperature and fluid composition history but also information on the nucleation and growth history. The formation of new metamorphic minerals requires non-equilibrium processes: nucleation, growth, and transport of constituents and heat from and to the mineral-growth site. We have started a comprehensive study of the kinetics of crystal growth in the realm of two subsequent National Science Foundation project (total of 5 years). Work started with the installation of a µX-ray tomography facility, which is now fully operational. Project A) request funding for 5 months to complete a Ph.D. project. This student (Bastien Darbellay) started his Ph.D. project on 1.9.2005. This part of the request is dedicated to finance the final months of the 4th year of his Ph.D. A continuation of the project is proposed with 2 PhD students. One to start in 1.4. 2009 (Caroline de Meyer), the other on 1.4.2010 (NN).Project A: Mineral growth in sedimentary rocks of the Zermatt-Saas zone (ZSZ):The Lu/Hf and Sm/Nd dating of garnets in high-pressure rocks have yielded crucial data for the development of models of subduction and exhumation of the ZSZ rocks in the Western Alps. In our previous work we have demonstrated that there are differences in ages obtained for the same minerals from the same rocks in the Zermatt-Saas Fee zone of the western Swiss Alps for Lu/Hf and Sm/Nd (Amato et al., 1999; Lape et al., 2003; Skora et al., in prep), using meta-mafic eclogites. We explained the age differences as the result of prograde mineral growth in an environment of diffusion limited REE incorporation (publ:??, Abstract ??). These results allow us to propose that the Zermatt-Saas zone is composed of slices of subducted oceanic crust which underwent metamorphism at different times. While dating has proven to be difficult but highly productive we have found that calculations of P-T-paths were very unsatisfactory due to missing thermo-data for Fe3+ in amphiboles and pyroxenes. The eclogites are highly oxidized rocks due to extended spilitization We propose to focus in the current proposal on the sedimentary rocks that are found intercalated in the ZSZ. Garnet growth kinetics and growth reactions will be investigated in these mostly carbonate bearing sediments to establish a P-T path. These data will be combined with Rb-Sr micro analysis and Ar-Ar analysis (including in-situ analysis) obtained from mica included in garnet to establish the timing of the prograde P-T path. These mica are chosen since we believe that they are the most likely to retain Rb/Sr and Ar/Ar chronology (see also Meffan-Main et al., 2004). Investigation of garnet growth mechanism will permit us to establish relative controls on garnet kinetics in these carbonate bearing rocks. I propose to also use the new dating evolving SIMS for epidote-minerals. Project B:Mineral growth and size of equilibrium domains in Sesia zone eclogites: This project is well advanced. In fact The PhD student, Bastien Darbellay will then be in the second half of his 4th year. Funding is sought for the remaining 5 months to finish publication of results and defense of his thesis. The focus of the study was to establish the equilibrium domain of trace and REE, as well as understanding zoisite and garnet growth in these spectacular rocks. Two manuscripts are currently prepared (Darbellay et al., a,b), one on atoll garnet growth, the other on hour glass textures in zoisite. Work on equilibrium domains is currently continuing and I propose to extend the study of project B) to include eclogites from the internal Sesia zone. Further on we are developing the model of Wilbur and Ague (2006a,b) further to include multiple elements to evaluate the relationship between garnet external form and zoning during a growth event.This proposal requests funding for the following items: 1) 5 months salary for a finishing Ph.D. student; 2) 3 years of Ph.D. student salary (project A, PhD 1) and 2 years of PhD student salary for project A, including field expenses and analytical costs.
-