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| Format: | Artículo científico |
| Language: | en |
| Published: |
Universitat de Barcelona
2007
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| Online Access: | https://www.redalyc.org/articulo.oa?id=50550101 |
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Table of Contents:
- The Upper Oligocene of Montgat (Catalan Coastal Ranges, Spain): new age constraints to the western editerranean Basin opening E. Roca D. Parcerisa D. Gómez-Gras J. Madurell J. Agustí Ciencias de la Tierra Chattian Compression Micromammal Alluvial fan Catalan Coastal Ranges The Oligocene deposits of Montgat are integrated in a small outcrop made up of Cenozoic and Mesozoic rockslocated in the Garraf-Montnegre horst, close to the major Barcelona fault. The Oligocene of Montgat consists ofdetrital sediments of continental origin mainly deposited in alluvial fan environments; these deposits are foldedand affected by thrusts and strike-slip faults. They can be divided in two lithostratigraphic units separated by aminor southwest-directed thrust: (i) the Turó de Montgat Unit composed of litharenites and lithorudites withhigh contents of quartz, feldspar, plutonic and limestone rock fragments; and (ii) the Pla de la Concòrdia Unitcomposed of calcilitharenites and calcilithorudites with high contents of dolosparite and dolomicrite rock fragments.The petrological composition of both units indicates that sediments were derived from the erosion of Triassic(Buntsandstein, Muschelkalk and Keuper facies), Jurassic and Lower Cretaceous rocks (Barremian to Aptianin age). Stratigraphic and petrological data suggest that these units correspond to two coalescent alluvialfans with a source area located northwestwards in the adjoining Collserola and Montnegre inner areas. Micromammalfossils (Archaeomys sp.) found in a mudstone layer of the Pla de la Concòrdia Unit assign a Chattianage (Late Oligocene) to the studied materials. Thus, the Montgat deposits are the youngest dated depositsaffected by the contractional deformation that led to the development of the Catalan Intraplate Chain. Takinginto account that the oldest syn-rift deposits in the Catalan Coastal Ranges are Aquitanian in age, this allows toprecise that the change from a compressive to an extensional regime in this area took place during latestOligocene-earliest Aquitanian times. This age indicates that the onset of crustal extension related to the openingof the western Mediterranean Basin started in southern France during latest Eocene-early Oligocene and propagatedsouthwestward, affecting the Catalan Coastal Ranges and the northeastern part of the Valencia troughduring the latest Chattian-earliest Aquitanian times. 2007 artículo científico 1695-6133 https://www.redalyc.org/articulo.oa?id=50550101 en http://www.redalyc.org/revista.oa?id=505 Geologica Acta: an international earth science journal application/pdf Universitat de Barcelona Geologica Acta: an international earth science journal (España) Num.1 Vol.5