Search results for "Eclogitization"
showing 4 items of 4 documents
Widening of Hydrous Shear Zones During Incipient Eclogitization of Metastable Dry and Rigid Lower Crust—Holsnøy, Western Norway
2021
The partially eclogitized crustal rocks on Holsnøy in the Bergen Arcs, Norway, indicate that eclogitization is caused by the interplay of brittle and ductile deformation promoted by fluid infiltration and fluid‐rock interaction. Eclogitization generated an interconnected network of millimeter‐to‐kilometer‐wide hydrous eclogite‐facies shear zones, which presumably caused transient weakening of the mechanically strong lower crust. To decipher the development of those networks, we combine detailed lithological and structural mapping of two key outcrops with numerical modeling. Both outcrops are largely composed of preserved granulite with minor eclogite‐facies shear zones, thus representing th…
Coeval high-pressure metamorphism, thrusting, strike-slip, and extensional shearing in the Tauern Window, Eastern Alps
2008
[1] Recent findings for a young (31.5 ± 0.7 Ma) age of high-pressure metamorphism at ∼90 km depths in the Eclogite Zone of the Tauern Window, Eastern Alps, prompt the question about the timing of the structural development of the Tauern Window and its relation to high-pressure metamorphism. We show that all major structures in the Tauern Window, resulting from strong N-S lithospheric shortening and simultaneous minor E-W extension, began developing coevally with high-pressure metamorphism in the Eclogite Zone. Large-scale strike-slip shear zones started to form at ∼32–30 Ma and facilitated the spatial accommodation of simultaneous shortening and extension. At least some of the strike-slip a…
Diffusion versus recrystallization processes in Rb–Sr geochronology: Isotopic relics in eclogite facies rocks, Western Gneiss Region, Norway
2008
Abstract Rb–Sr and U–Pb isotopic data for granulite facies rocks, forming textural relics with respect to eclogite facies metamorphism in the Western Gneiss Region (WGR) of Norway, highlight the importance of textures and mineral reaction kinetics for the interpretation of geochronological data. Studied rocks from Bardsholmen, southern WGR, were subjected to granulite facies metamorphism at 955 ± 3 Ma (U–Pb, zircon). Later on, they experienced a subduction-related, kinetically stranded eclogitization ( T > 650 °C at ∼20 kbar) at 404 ± 2 Ma (Rb–Sr multimineral internal isochron data), followed by exhumation through amphibolite facies conditions. Full conversion of granulite to eclogite was …
Shear heating induced lithospheric-scale localization: Does it result in subduction?
2012
Abstract Even though it is a well-established fact that the Earth is currently in a plate-tectonics mode, the question on how to “break” lithospheric plates and initiate subduction remains a matter of debate. Here we focus on shear heating as a potential mechanism to cause lithospheric shear localization and subsequent subduction initiation in oceanic plates. It is shown that shear heating under some conditions (i) facilitates the formation of a lithospheric-scale shear zone and (ii) is capable of stabilizing a lithospheric-scale shear zone, thus creating the necessary condition for subduction initiation to occur. Furthermore, we demonstrate that not only the localization process is of impo…