--> Abstract: Miocene Tectonics, Relief, Surface Geology, and Sedimentation in the Eastern Alps, by W. Frisch, J. Kuhlemann, I. Dunkl, and A. Brugel; #90942 (1997).

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Abstract: Miocene tectonics, relief, surface geology, and sedimentation in the Eastern Alps

FRISCH, W., J. KUHLEMANN, I. DUNKL, and A. BRUGEL

The Miocene tectonics of the Eastern Alps is governed by frontal thrusting, strike-slip movement in a complex block puzzle, pull-apart of the upper-plate (Austroalpine) rigid orogenic lid enabling metamorphic domes to rise under the formation of large-sized lower-plate (Penninic) tectonic windows, and heterogeneous uplift and erosion. Vertical and N-S horizontal shortening is compensated by E-W horizontal extension in connection with subduction rollback in the Pannonian basin. Exhumation and erosion (circum-orogenic basin sediment accumulation) rates indicate that denudation of the Penninic windows was fundamentally a tectonic process. Early to Middle Miocene average erosion is estimated to have been in the order of 0.2 mm per year in the mountainous areas, while tectonic denudation above the Tauern window attained an average of 1.5 to 2 mm per year, with short-term higher values.

The sedimentary records in the intramontane and circum-orogenic basins give valuable information about exhumation, evolution of relief and drainage pattern, and exposed lithologic units in the hinterland. Marker pebble and fission track analyses from sand fractions and pebble populations are the main tools for the reconstruction of paleogeologic and paleotopographic maps. Fission track ages from the foreland molasse allow to define areas of Late Cretaceous/Early Tertiary and of Oligo-Miocene denudation. Apatite ages only 3-4 Ma older than the sedimentation indicate rapid exhumation in the hinterland. Petrologic, chemical and geochronologic evidences from molasse pebbles indicate the first appearance of the Penninic contents of the Tauern window.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria