Ph.D. project 2009-2012, Fully funded (1,757.00 € gross monthly income)

The aim of this Ph.D. project is to use a multidisciplinary approach combining petrologic, geochemical and thermochronologic source-area indicators, in order to reconstruct the evolution of erosion and sediment routing in the western Alps during Oligocene and Miocene times.

The record of this evolution is preserved in the pro- and retro-side basins of the western Alps in France and Italy. Several studies on heavy minerals and index minerals have been done in these basins to discriminate sediment source areas, but still some confusion exists concerning the provenance of certain heavy minerals. For example, on the basis of new studies on metamorphic rocks in the western Alps it is now possible to discriminate between sillimanite, staurolite, kyanite, andalousite, glaucophane and Na-clinopyroxene derived from the internal and external western Alps. However, serpentine group minerals can be derived from two main sources. The first is an ophiolitic source such as the Chenaillet ophiolite that escaped Alpine metamorphism. This potential source is characterized by chrysotile and lizardite serpentine minerals. The second potential serpentine source in the western Alps are metamorphic rocks in the Piedmont, Schistes Lustrés, and Monviso units, which are dominated by antigorite minerals. By using combined XRD and Raman spectrometry the mineralogy of detrital serpentine group minerals will be determined precisely, in order to discriminate metamorphic and non-metamorphic sources. This is done to test the hypothesis that the metamorphic rocks of the internal western Alps were exhumed successively, which means that younger molasse sediments contain detritus from more deeply exhumed rocks of the internal Alps than older molasses sediments. In addition, fission-track analysis of bedrock and detrital apatite and zircon, and 40Ar/39Ar thermochronology of white mica are excellent tools for studying the cooling history of orogenic sediment source areas. Because the three systems have different closure temperatures, they are sensitive to upper crustal exhumation processes, such as erosion and normal faulting, on different time scales. Because of volcanic activity in the Alps at around 30 Ma it will be crucial to supplement fission-track dating of detrital zircon with U-Pb analysis on the same individual grains (double-dating) to clearly identify zircon of volcanic origin which may bias the erosional exhumation signal.

Therefore, source area characterization using a multidisciplinary petrologic, geochemical and thermochronologic approach on detrital and bedrock samples is the overall theme of this three-year Ph.D. project. This project will be supported by Master student projects which will be focused on certain minor aspects of the Ph.D. project. This project is financially supported through an ANR research fund.

Starting date is September 1^st 2009.

For further or to apply please send a letter of motivation, CV and name and addresses of two references to Matthias Bernet matthias.bernet@ujf-grenoble.fr.

Application deadline June 26^th 2009