Thermal effects of exhumation of a metamorphic core complex on hanging wall syn-rift sediments: An example from the Rechnitz Window, Eastern Alps

István Dunkl, Bernhard Grasemann, Wolfgang Frisch

    Veröffentlichungen: Beitrag in FachzeitschriftArtikelPeer Reviewed

    Abstract

    The removal of overburden by tectonic processes displaces the rock masses and their temperature with respect to the surface. Consequently high cooling rates and increased heat flow have been reported from rapidly exhuming terrains. Previous studies were mainly focused on the greenschist- and amphibolite-facies tectono-thermal evolution of the footwall. A two-dimensional numerical thermal model presented in this study concentrates on the thermal history of the hanging wall and the footwall blocks and evaluates the variation of the near-surface heat flow above an evolving metamorphic core complex. Based on structural, thermobarometric and geochronological constraints from the Rechnitz core complex of the Eastern Alps the modelling suggests that rapid movement along the extensional fault took place between 22 and 17 Ma. During this period the heat flow reached values of 140-150 mW/m2 in the hanging wall in a 10-15-km-wide zone parallel to the fault trace. The increased heat flow caused the high coal rank in the Miocene syn-rift sediments deposited on the hanging wall. Apatite fission track geochronology of the thermally overprinted sedimentary deposits gives the time at which the bottom of the syn-rift sediment pile passed through 110°C (13.6 ± 0.9 Ma). The vitrinite reflectance data (R(r): 0.67-1.04%) suggest significant burial of the margin of the hanging wall at the time of core complex formation. Considering the coal rank data and the thermal conductivity of the sedimentary deposits by modelling of the organic maturation we calculate syn-rift (Early-Middle Miocene) burial of the hanging wall margin of the Rechnitz core complex to be 1100-1600 m. This value shows the importance of the post-Middle Miocene erosion of the region, which was related to the inversion of the Pannonian basin.

    OriginalspracheEnglisch
    Seiten (von - bis)31-50
    Seitenumfang20
    FachzeitschriftTectonophysics
    Jahrgang297
    Ausgabenummer1-4
    DOIs
    PublikationsstatusVeröffentlicht - 20 Nov. 1998

    ÖFOS 2012

    • 105106 Geodynamik

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