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Intracrystalline deformation of calcite in the upper brittle crust

Helene Bauer, A. Rogowitz, Bernhard Grasemann and K. Decker
Intracrystalline deformation of calcite in the upper brittle crust
Geology (Boulder) (April 2018) 46 (4): 375-378

Abstract

This study presents unexpected microstructures in carbonate fault rocks that formed in the Salzach-Ennstal-Mariazell-Puchberg fault (Austria), which accommodated lateral extrusion of the Eastern Alps in the Oligocene and Miocene. The investigated eastern part of the sinistral strike-slip fault exposes a shallow crustal, brittle segment. Deformation mechanisms in the carbonate fault rocks involve cataclasis, fracturing, pressure solution-assisted creep, and intracrystalline creep. Besides deformation twinning, intracrystalline deformation of calcite includes dislocation activity present as undulose extinction and development of low-angle grain boundaries. Intracrystalline deformation under these conditions proves the existence of very low-temperature (<150 degrees C) ductile deformation in calcite. Because intracrystalline deformation in calcite is restricted to centimeter-scale secondary shear zones, and evidence for both internal and external heat sources is lacking, we speculate that intracrystalline deformation typical of higher metamorphic shear zones in marbles can operate under temperature conditions <150 degrees C.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 46
Serial Issue: 4
Title: Intracrystalline deformation of calcite in the upper brittle crust
Affiliation: University of Vienna, Department for Geodynamics and Sedimentology, Vienna, Austria
Pages: 375-378
Published: 201804
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 28
Accession Number: 2018-043950
Categories: Sedimentary petrologyStructural geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2018121
Illustration Description: illus. incl. geol. sketch map
N47°00'00" - N48°00'00", E14°00'00" - E15°30'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 2018
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