The Austroalpine Campo basement outcrops south of the Cretaceous Vinschgauer shear zone (VSZ). This shear zone separates the Austrolapine Ötztal basement in the North from the Campo basement in the South. In the Martell Valley, a tributary valley of the Vinschgau Valley, the Campo crystalline basement is characterized by a thrust system traditionally called “Zebrù Schuppenzone” (in Italian “scaglia dello Zebrù”). In this master thesis I have focused my field and analytical work on the Zebrù Schuppenzone SW of the Zufrittsee (Lago di Gioveretto). Specifically, I have studied oriented samples from an exceptionally well exposed outcrop that allowed to discriminate the overprinting relationships within a discrete shear zone, here called the Zebrù shear zone (ZSZ), hosted within the polymetamorphic metasedimentary metamorphic basement, already in the field. To study the ZSZ a combined approach of microstructural and microchemical analysis was applied. To this aim, thin sections cut parallel to the 195/40 plunging stretching lineation contained within a S/40° dipping mylonitic foliation have been studied firstly under the petrographic microscope. This analysis allowed the recognition of fine-grained mineral aggregates pseudomorphic of high-pressure phases within the mylonites of the ZSZ. Energy dispersive spectroscopy (EDS) mapping and standardized micro-analysis suggest that these pseudomorphs are the product of blueschist metamorphic leftovers within the Austroalpine basement and formed reasonably during the closure of Meliata Ocean in the Early Creataceous. The overprinting of the blueschist facies metamorphic remnants within the ZSZ has occurred during exhumation of the high pressure-low temperature rocks along the ZSZ. The overprinting occurred under low greenschist facies metamorphic conditions in the neo-Alpine. This is documented by stability calculations of mineral phases as well as by EBSD analysis of quartz and albite crystals and the resulting rheological constraints.
The Austroalpine Campo basement outcrops south of the Cretaceous Vinschgauer shear zone (VSZ). This shear zone separates the Austrolapine Ötztal basement in the North from the Campo basement in the South. In the Martell Valley, a tributary valley of the Vinschgau Valley, the Campo crystalline basement is characterized by a thrust system traditionally called “Zebrù Schuppenzone” (in Italian “scaglia dello Zebrù”). In this master thesis I have focused my field and analytical work on the Zebrù Schuppenzone SW of the Zufrittsee (Lago di Gioveretto). Specifically, I have studied oriented samples from an exceptionally well exposed outcrop that allowed to discriminate the overprinting relationships within a discrete shear zone, here called the Zebrù shear zone (ZSZ), hosted within the polymetamorphic metasedimentary metamorphic basement, already in the field. To study the ZSZ a combined approach of microstructural and microchemical analysis was applied. To this aim, thin sections cut parallel to the 195/40 plunging stretching lineation contained within a S/40° dipping mylonitic foliation have been studied firstly under the petrographic microscope. This analysis allowed the recognition of fine-grained mineral aggregates pseudomorphic of high-pressure phases within the mylonites of the ZSZ. Energy dispersive spectroscopy (EDS) mapping and standardized micro-analysis suggest that these pseudomorphs are the product of blueschist metamorphic leftovers within the Austroalpine basement and formed reasonably during the closure of Meliata Ocean in the Early Creataceous. The overprinting of the blueschist facies metamorphic remnants within the ZSZ has occurred during exhumation of the high pressure-low temperature rocks along the ZSZ. The overprinting occurred under low greenschist facies metamorphic conditions in the neo-Alpine. This is documented by stability calculations of mineral phases as well as by EBSD analysis of quartz and albite crystals and the resulting rheological constraints.
Metasediments exhumed along the Zebrù shear zone in the Martell Valley (South Tyrol) record eo-Alpine blueschist facies metamorphism
OSTI, RUDI
2023/2024
Abstract
The Austroalpine Campo basement outcrops south of the Cretaceous Vinschgauer shear zone (VSZ). This shear zone separates the Austrolapine Ötztal basement in the North from the Campo basement in the South. In the Martell Valley, a tributary valley of the Vinschgau Valley, the Campo crystalline basement is characterized by a thrust system traditionally called “Zebrù Schuppenzone” (in Italian “scaglia dello Zebrù”). In this master thesis I have focused my field and analytical work on the Zebrù Schuppenzone SW of the Zufrittsee (Lago di Gioveretto). Specifically, I have studied oriented samples from an exceptionally well exposed outcrop that allowed to discriminate the overprinting relationships within a discrete shear zone, here called the Zebrù shear zone (ZSZ), hosted within the polymetamorphic metasedimentary metamorphic basement, already in the field. To study the ZSZ a combined approach of microstructural and microchemical analysis was applied. To this aim, thin sections cut parallel to the 195/40 plunging stretching lineation contained within a S/40° dipping mylonitic foliation have been studied firstly under the petrographic microscope. This analysis allowed the recognition of fine-grained mineral aggregates pseudomorphic of high-pressure phases within the mylonites of the ZSZ. Energy dispersive spectroscopy (EDS) mapping and standardized micro-analysis suggest that these pseudomorphs are the product of blueschist metamorphic leftovers within the Austroalpine basement and formed reasonably during the closure of Meliata Ocean in the Early Creataceous. The overprinting of the blueschist facies metamorphic remnants within the ZSZ has occurred during exhumation of the high pressure-low temperature rocks along the ZSZ. The overprinting occurred under low greenschist facies metamorphic conditions in the neo-Alpine. This is documented by stability calculations of mineral phases as well as by EBSD analysis of quartz and albite crystals and the resulting rheological constraints.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/69581