GEO3BCN&UB Seminars

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ABSTRACT

 

At convergent plate margins part of the continental crust can be buried at great depth (i.e. subducted), exhumed back to the surface and accreted to a newly-formed orogen. During this process a pre-existing crust, comprising, for example, remnants of an older orogen, is recycled. Pervasive metamorphic transformations at high-pressure (HP) or even ultra-high-pressure (UHP) conditions overprint the pre-subduction rock record. However, an attentive investigation can reveal mineralogical, structural and isotopic relicts of the older geologic history, despite pervasive HP re-equilibration. In this seminar we will use petrological and geochronological evidence to reconstruct the polymetamorphic history of the renowned (U)HP Dora-Maira Massif (Western Alps). This allows us to investigate how pre-subduction characters (such as H 2 O content) affect the response of rocks to HP re-equilibration during subduction.