ISSN:
0016-7835
Keywords:
Key words Low-temperature metamorphism
;
K-Ar dating
;
Fission track dating
;
Illite 'crystallinity'
;
Carpathians
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
Notes:
Abstract K-Ar ages of illite-muscovite and fission track ages of zircon and apatite were determined from various lithotypes of the Bükkium, which forms the innermost segment of the Western Carpathians. The stratigraphic ages of these Dinaric type formations cover a wide range from the Late Ordovician up to the Late Jurassic. The grade of the orogenic dynamo-thermal metamorphism varies from the late diagenetic zone through the 'anchizone' up to the 'epizone' (chlorite, maximally biotite isograd of the greenschist facies). The K-Ar system of the illite-muscovite in the 〈2 μm grain-size fraction approached equilibrium only in 'epizonal' and high-temperature 'anchizonal' conditions. The orogenic metamorphism culminated between the eo-Hellenic (160–120 Ma) phase connected to the beginning of the subduction in the Dinarides, and the Austrian (100–95 Ma) phase characterized by compressional crustal thickening. No isotope geochronological evidence was found for proving any Hercynian recrystallization. The stability field of fission tracks in zircon was approached using the thermal histories of the different tectonic units. A temperature less than 250° C and effective heating time of 20–30 Ma had only negligible effects on the tracks, whereas total annealing was reached between 250 and 300° C. Apatite fission track ages from the Paleozoic and Mesozoic formations show that the uplift of the Bükk Mountains occurred only in the Tertiary (not earlier than ca. 40 Ma ago). Thermal modeling based on apatite fission track length spectra and preserved Paleogene sediment thickness data proved that the Late Neogene burial of the recently exhumed plateau of the Bükk Mountains exceeded 1 km.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00260444
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