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Earth Sciences at the University of Fribourg

Bern-Fribourg Master in Earth Sciences


Details of Master Thesis Topic (Module D):
Subduction zone history of an oceanic slab unit in the tectonic accretionary channel of the Alps

Master Thesis title: Subduction zone history of an oceanic slab unit in the tectonic accretionary channel of the Alps
Description:Along the subduction plate interface melange series occur that contain fragments of subducted hydrous oceanic lithosphere, its sedimentary cover, and mantle wedge material, all variably modified in response to fluid-rock interaction during the subduction cycle. The fate of such fragments during subduction and exhumation has remained controversial, however, with models proposing that such fragments remain coherent during the entire cycle and models proposing that the units we now find exposed are the product of late amalgamation during exhumation along the plate interface. This project will investigate in detail one body (to be identified) of hydrous mantle rocks associated with basaltic eclogite and ±sediments from the Central Alps (Ticino) to decipher its metamorphic history during the subduction cycle and to constrain the trace element inventory of the different rock units. Such results are essential to our better understanding of subduction zone geochemical cycling and geodynamics.

Sample materials will be collected and detailed outcrop mapping will be performed during field work in the Central Alps; hence, safe mountaineering in steep, pathless terrains is of advantage. Petrographic characterization of thin sections forms the basis for electron probe and laser ablation-ICP-MS measurements and chemical mapping to constrain the petrochemistry of the diverse fragment constituents. Continuing research can focus either on mineral stabilities and transformations employing modelling, on dating subduction metamorphism, or on chemical interactions between different rocks in the oceanic fragment – to be decided according to student’s interests.
Advisors:Prof. Thomas Pettke, Prof. Jörg Hermann
Specialities:EM, GEOL
University: BE

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