title: Structure and evolution of a rocksalt-mudrock-tectonite: The haselgebirge in the Northern Calcareous Alps.
abstract: The Northern Calcareous Alps are part of the Eastern Alps in Austria and Germany. The Mesozoic units of this fold-and-thrust belt were detached, thrusted and stacked along the evaporitic Haselgebirge Formation. Exposed in salt mines, rocksalt and mudrock form a two component tectonite: The rock type "haselgebirge" consists of 10-70 wt % halite with silt- to gravel- or block-sized components within a halite matrix, and the "kerngebirge" with >70 wt % halite. All rock types studied are fault rocks. By use of a temperature-independent subgrain size piezometer, the paleo-differential stress of halite was calculated at ca. 2.5 MPa in Altaussee and ca. 4.5 MPa in Berchtesgaden. Including data from a grain-size piezometer, temperatures were estimated at ca. 150 ± 20 °C and 110 ± 10 °C. This implies very high strain rates, which are about 10-10-10-9s-1. During the tectonic movement, the halite deformed, recrystallized, and crystallized as veins in mudrock fractures. We interpret high overpressure of the pore fluid to have significantly contributed to fracturing of the mudrock.
authors.affiliation: Fachbereich für Geographie und Geologie, Universität Salzburg, Hellbrunnerstraße 34, 5020 Salzburg, Austria.
authors.forename: Christoph
authors.initials: C
authors.lastname: Leitner
authors.affiliation: Fachbereich für Geographie und Geologie, Universität Salzburg, Hellbrunnerstraße 34, 5020 Salzburg, Austria.
authors.forename: Franz
authors.initials: F
authors.lastname: Neubauer
authors.affiliation: Geologie-Endogene Dynamik, RWTH Aachen, Lochnerstraße 4-20, 52056 Aachen, Germany.
authors.forename: János L
authors.initials: JL
authors.lastname: Urai
authors.affiliation: Exxon Mobil Upstream Research Company, Carbonate Reservoir Performance Prediction, 3319 Mercer Street, Houston, TX 77027, USA.
authors.forename: Johannes
authors.initials: J
authors.lastname: Schoenherr
keywords: Alps; Halite; Haselgebirge; Hydrofracturing of mudrock; Northern Calcareous Alps; Rocksalt