HR: 1340h
AN: GP43C-1492    [Abstracts]
TI: Chronology of the Final Marine Regression in the Eastern Ebro Basin: Late Eocene to Early Oligocene Tectonosedimentary Evolution. (NE Spain)
AU: * Costa, E
EM: elicosta@ub.edu
AF: Grup de Geodinamica i Analisi de Conques, Dpt. Estratigrafia, P. i GCM Facultat de Geologia Marti i Franques s n, Barcelona, 08028, Spain
AU: Garces, M
EM: mgarces@ub.edu
AF: Grup de Geodinamica i Analisi de Conques, Dpt. Estratigrafia, P. i GCM Facultat de Geologia Marti i Franques s n, Barcelona, 08028, Spain
AU: Saez, A
EM: a.saez@ub.edu
AF: Grup de Geodinamica i Analisi de Conques, Dpt. Estratigrafia, P. i GCM Facultat de Geologia Marti i Franques s n, Barcelona, 08028, Spain
AU: Lopez-Blanco, M
EM: m.lopezblanco@ub.edu
AF: Grup de Geodinamica i Analisi de Conques, Dpt. Estratigrafia, P. i GCM Facultat de Geologia Marti i Franques s n, Barcelona, 08028, Spain
AU: Beamud, E
EM: betbeamud@ub.edu
AF: Laboratori de Paleomagnetisme UB-CSIC, ICT Jaume Almera Sole i Sabaris s n, Barcelona, 08028, Spain
AU: Gomez-Paccard, M
EM: mgomezpaccard@ub.edu
AF: Grup de Geodinamica i Analisi de Conques, Dpt. Estratigrafia, P. i GCM Facultat de Geologia Marti i Franques s n, Barcelona, 08028, Spain
AU: Cabrera, L
EM: lluis.cabrera@ub.edu
AF: Grup de Geodinamica i Analisi de Conques, Dpt. Estratigrafia, P. i GCM Facultat de Geologia Marti i Franques s n, Barcelona, 08028, Spain
AB: The Ebro Basin is a triangular shaped foreland basin surrounded by three alpine ranges: the Pyrenees to the north, the Iberian Range to the SW and the Catalan Coastal Range to the SE. During the early Paleocene started the development of the Ebro Basin by flexural subsidence related to the growth of its margins as a consequence of the continental collision of Iberia and Europe. Connection of the Ebro Basin with the open sea was maintained until late Eocene, when ongoing convergence along the Pyrenean margin lead to the final closure of its western connection with the Atlantic Ocean. Since then, a long endorheic period of uninterrupted continental sedimentation leads to the accumulation of a thick sequence composed by alluvial and lacustrine facies. In foreland basins, tectonics plays a fundamental role in the sedimentation, by generating relief in the margins and accommodation space in the basin. Therefore, it is generally assumed that the main sedimentary breaks have a tectonic origin. The tectonic control on the sedimentation has been successfully established along the margins of the Ebro Basin through the study of the geometries of the syntectonic sediments. However, away from the margins, in distal alluvial and lacustrine environments some other factors related to the climate can also exert control on the sedimentation. In order to interpret the sedimentary record of the Ebro Basin in terms of tectonosedimentary and paleoclimatic evolution, we have sampled two magnetostratigraphic sections (1000 m and 600 m, thick) on Eocene-Oligocene continental sequences. Samples were collected at 2-5 m stratigraphic intervals. Stepwise thermal demagnetisation of the NRM of up to 2 samples per site has yielded a local magnetic polarity stratigraphy. Unambiguous correlation with the geomagnetic polarity time scale was feasible based on the presence of late Eocene to early Oligocene mammal fossil localities and previous magnetostratigraphic studies spanning the complete Oligocene stratigraphic record. Conclusions of this study provide reliable age constraints for the marine-continental transition and helps understanding the Late Eocene to Early Oligocene tectonosedimentary evolution of the eastern Ebro Basin.
DE: 1165 Sedimentary geochronology
DE: 1520 Magnetostratigraphy
DE: 1527 Paleomagnetism applied to geologic processes
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting