Intracrystalline deformation of calcite in the upper brittle crust

H. Bauer, A. Rogowitz, B. Grasemann, K. Decker

Publications: Contribution to journalArticlePeer Reviewed

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 °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 °C.

Original languageEnglish
Pages (from-to)375-378
Number of pages4
JournalGeology
Volume46
Issue number4
DOIs
Publication statusPublished - 1 Apr 2018

Austrian Fields of Science 2012

  • 105106 Geodynamics
  • 105124 Tectonics

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