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The tectonometamorphic evolution of the Apuseni Mountains during the Cretaceous : investigations on the interplay between tectonics and surface processes in the build-up of a source area / Martin Kaspar Reiser
VerfasserReiser, Martin Kaspar
Begutachter / BegutachterinnenWillingshofer, Ernst ; Kounov, Alexandre
Betreuer / BetreuerinnenFügenschuh, Bernhard
Umfang156 S. : zahlr. Ill., graph. Darst., Kt.
HochschulschriftInnsbruck, Univ., Diss., 2015
Datum der AbgabeFebruar 2015
Schlagwörter (DE)Apuseni Mountains / Thermochronology / Geochronology / Fission / Tectonics / Tisza / Dacia / Cretaceous / Source-to-Sink / Biharia
Schlagwörter (GND)Kreide / Westsiebenbürgisches Gebirge / Theiß / Dakien / Geochronologie / Tektonik
URNurn:nbn:at:at-ubi:1-2287 Persistent Identifier (URN)
 Das Werk ist frei verfügbar
The tectonometamorphic evolution of the Apuseni Mountains during the Cretaceous [9.7 mb]
Zusammenfassung (Deutsch)

New structural, thermobarometric and geochronological data allow integrating kinematics, timing and intensity of tectonic phases into a geodynamic model of the Apuseni Mountains, which provides new constraints for the evolution of the Alps-Carpathians-Dinaride system of orogens. Similarities in the tectonometamorphic evolution of the Tisza and Dacia Mega-Units suggest a parallel evolution during the Cretaceous, without the inevitable need of a separating ocean between these two units. New geochronological and structural data prove a Late Jurassic emplacement of the South Apuseni Ophiolites on top of the Biharia Nappe System (Dacia Mega-Unit), situated in an external position at the European margin. Ongoing NE-directed movement during the Early Cretaceous caused in-sequence nappe stacking and regional metamorphic overprinting under amphibolite-facies conditions in the Tisza and Dacia Mega-Units. Syn- to post-tectonic sediments, unconformably overlying the ophiolites on top of the Biharia Nappe System, indicate a position of the ophiolites at or close to the surface from late Early Cretaceous times on. A lateral, E-directed trend from Variscan to Alpine ages, as well as thermochronological data and P-T estimates from the Bihor Nappe constrain differential exhumation of basement units by some 812 km following Early Cretaceous nappe stacking. E-directed exhumation along a low-angle detachment is supported by stretching lineation and kinematic data from the contact area between Biharia s.str., Bihor and Codru Nappes. Partial tectonic omission of the Codru Nappe in the eastern Apuseni Mountains is most likely linked to this exhumation. NW-directed thrusting during the Turonian Phase overprinted previous structures under greenschist-facies conditions and reset zircon fission track ages in all but the stratigraphically highest nappes of the eastern Apuseni Mountains. Non-reset late Early Cretaceous zircon fission track ages and less intense overprinting of structural features from previous tectonic events constrain a decreasing effect of Turonian Phase deformation towards the western part of the Apuseni Mountains. Thus, NW-SE trending nappe contacts in the western Apuseni Mountains represent the situation after Early Cretaceous nappe stacking. Late Cretaceous extension reactivated former thrust contacts as brittle normal faults which act as master faults of half graben basins. SantonianMaastrichtian post-tectonic sediments fill these basins and seal the nappe contacts. The last episode of tectonic activity during the Late Cretaceous (”Laramian Phase”) is evidenced through general uplift and inversion of sedimentary basins. Multiple reactivations of Early Cretaceous tectonic contacts underline the importance of inherited structures for the tectonometamorphic evolution of the Apuseni Mountains. The spatial and temporal relationship between the basement and the stratigraphic record in sedimentary basins throughout the Cretaceous indicates a close interaction between tectonics, erosion and deposition.

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