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Fission-track constraints on the thermal and tectonic evolution of the Apuseni Mountains (Romania).
- Source :
-
International Journal of Earth Sciences . Jan2013, Vol. 102 Issue 1, p207-233. 27p. 2 Color Photographs, 3 Diagrams, 1 Chart, 7 Graphs, 3 Maps. - Publication Year :
- 2013
-
Abstract
- New zircon and apatite fission-track (FT) data, including apatite thermal modelling, are combined with an extensive literature survey and reconnaissance-type structural fieldwork in the Eastern Apuseni Mountains. This leads to a better understanding of the complex structural and thermal history of a key area at the boundary between two megatectonic units in the Balkan peninsula, namely the Tisza and Dacia Mega-Units. Following Late Jurassic obduction of the Transylvanian ophiolites onto a part of the Dacia Mega-Unit, that is, the Biharia nappe system, both units were buried to a minimum of 8 km during late Early Cretaceous times when these units were underthrust below the Tisza Mega-Unit consisting of the present-day Codru and Bihor nappe systems. Tisza formed the upper plate during Early Cretaceous ('Austrian') east-facing orogeny. Turonian to Campanian zircon FT cooling ages (95-71 Ma) from the Bihor and Codru nappe systems and the Biharia and Baia de Arieş nappes (at present the structurally lowest part of the Dacia Mega-Unit) record exhumation that immediately followed a second Cretaceous-age (i.e. Turonian) orogenic event. Thrusting during this overprinting event was NW-facing and led to the overall geometry of the present-day nappe stack in the Apuseni Mountains. Zircon FT ages, combined with thermal modelling of the apatite FT data, show relatively rapid post-tectonic cooling induced by a third shortening pulse during the latest Cretaceous ('Laramian' phase), followed by slower cooling across the 120°-60 °C temperature interval during latest Cretaceous to earliest Paleogene times (75-60 Ma). Cenozoic-age slow cooling (60-40 Ma) was probably related to erosional denudation postdating 'Laramian' large-scale updoming. [ABSTRACT FROM AUTHOR]
- Subjects :
- *STRUCTURAL geology
*ZIRCON
*PALEOGENE
*CRETACEOUS Period
Subjects
Details
- Language :
- English
- ISSN :
- 14373254
- Volume :
- 102
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- International Journal of Earth Sciences
- Publication Type :
- Academic Journal
- Accession number :
- 84739925
- Full Text :
- https://doi.org/10.1007/s00531-012-0800-5