Podrobnosti záznamu

    Extreme ductile deformation of fine-grained salt by coupled solution-precipitation creep and microcracking: Microstructural evidence from perennial Zechstein sequence (Neuhof salt mine, Germany)
    Desbois, Guillaume
    Lexa, Ondrej
    Schwedt, Alexander
    Urai, Janos L.
    Závada, Prokop
Typ dokumentu
    článek v periodiku
Zdrojový dokument - seriál
    Journal of Structural Geology
    Roč. 37, č. April
Výraz tezauru
    Fluid inclusion trails
    Griffith crack
    Perennial lake
    Rock salt
    Salt rafts
    Solution-precipitation creep
Klíčové slovo
Abstrakt (anglicky)
   Microstructural study revealed that the ductile flow of intensely folded fine-grained salt exposed in an underground mine (Zechstein-Werra salt sequence, Neuhof mine, Germany) was accommodated by coupled activity of solution-precipitation (SP) creep and microcracking of the halite grains. The grain cores of the halite aggregates contain remnants of sedimentary microstructures with straight and chevron shaped fluid inclusion trails (FITs) and are surrounded by two concentric mantles reflecting different events of salt precipitation. Numerous intra-granular or transgranular microcracks originate at the tips of FITs and propagate preferentially along the interface between sedimentary cores and the surrounding mantle of reprecipitated halite. These microcracks are interpreted as tensional Griffith cracks. Microcracks starting at grain boundary triple junctions or grain boundary ledges form due to stress concentrations generated by grain boundary sliding (GBS). Solid or fluid inclusions fre
   quently alter the course of the propagating microcracks or the cracks terminate at these inclusions. Because the inner mantle containing the microcracks is corroded and is surrounded by microcrack-free outer mantle, microcracking is interpreted to reflect transient failure of the aggregate. Microcracking is argued to play a fundamental role in the continuation and enhancement of the SP GBS creep during halokinesis of the Werra salt, because the transgranular cracks (1) provide the ingress of additional fluid in the grain boundary network when cross-cutting the FITs and (2) decrease grain size by splitting the grains. Described readjustments of the microstructure and mechanical and chemical feedbacks for the grain boundary diffusion flow in halite-brine system are proposed to be comparable to other rock-fluid or rock-melt aggregates deforming by the grain boundary sliding (GBS) coupled deformation mechanisms.
    UK Praha, Přírodovědecká fakulta
Kód přispěvatele
    UK, PřF
Zdrojový formát
Datum importu
    27. 4. 2014