Late Cretaceous exhumation history of an extensional extruding wedge (Graz Paleozoic Nappe Complex, Austria) |
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| Authors: | Krenn Kurt Fritz Harald Mogessie Aberra Schaflechner Johannes |
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| Institution: | 1. Institute of Earth Sciences, Department of Mineralogy and Petrology, University of Graz, Universit?tsplatz 2, Graz, Austria
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| Abstract: | Late Cretaceous structures within the eastern Graz Paleozoic Nappe Complex define an extruding wedge with north-eastward directed
thrusting in eastern portions and strike-slip shear along the margins. Stacking structures are overprinted by south-westward
directed extension with low-grade metamorphic rocks in the hangingwall and high-grade basement rocks in the footwall. Pressure–temperature
and structural data are obtained from successively opening quartz veins that record various stages of progressive deformation
and metamorphism. Fluid inclusion data and related structures show that during extension isothermal decompression from ca.
550°C and 8 kbar down to ca. 450°C and 2 kbar was related to exhumation of rocks from deep crustal levels. The data point
to a high geothermal gradient and explain condensed paleo-isotherms due to ductile normal faulting in the eastern areas of
the Graz Paleozoic Nappe Complex. The investigated Late Cretaceous structural elements suggest that the Graz Paleozoic Nappe
Complex decoupled from the surrounding basement units and operated as a large-scale extension–extrusion corridor that evolved
prior to Miocene extrusion tectonics in the Eastern Alps. |
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| Keywords: | Graz Nappe Complex Eastern Alps Late Cretaceous extension Extrusion Fluid inclusions |
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