La cuenca neógena de Fortuna, Cordilleras Béticas: magnetoestratigrafía y evolución tectonosedimentaria

• M. Garcés ^[1] ; W. Krijgsman ^[2] ; J. Agustí ^[3]
  1. [1] Instituto de Ciencias de la Tierra Jaume Almera

     Instituto de Ciencias de la Tierra Jaume Almera

     Barcelona, España

     
  2. [2] Paleomagnetic Laboratory Fort Hoofddijk
  3. [3] Institut de Paleontología Miquel Crusafont

  Mostrar afiliaciones +
• Localización: Geotemas (Madrid), ISSN 1576-5172, Nº. 2, 2000 (Ejemplar dedicado a: IV Congreso del Grupo Español del Terciario (Tremp, 19-21 septiembre, 2000)), págs. 81-85
• Idioma: español
• Enlaces
  • Texto Completo Ejemplar
• Resumen

  • The Fortuna basin is an elongated trough which developed on a NE-SW trending shear zone at the boundary between the External and Internal Zones of the eastern Betics. The depositional history of the Fortuna basins is marked by a regressive sequence from open marine marls, via diatomites and evaporites, to continental sediments. Based on facies similarities, these evaporites have often been correlated to the well-known Mediterranean evaporites of the Messinian salinity crisis, although this correlation was never substantiated by reliable chronological data. In this paper we present a new magnetochronology for the late Tortonian to Pliocene deposits of the Fortuna basin. The derived paleogeographic and geodynamic scenario challenges previous interpretations of the Fortuna basin sedimentary record. The early (~8 Ma) progressive isolation of the Fortuna basin from the open Mediterranean basin occurred in relation to a late Tortonian tectonic uplift of the Internal Zones of the Betic chain. Rising of an eastern margin caused rapid sedimentation and continentalisation of the basin. The onset of the basin confinement is marked by the development of restricted marine environments and the deposition of the well known evaporitic and diatomitic formations (7.9 to 7.6 Ma). Tectonic subsidence in the basin continued from late Tortonian up to the lower Pliocene leading to the accumulation of more than I km of continental deposits. Folding of these sediment sequences and localised counterclockwise block rotations evidence a phase of compression and left-lateral shear along the southeastern basin margin, announcing the end of the sedimentation and subsequent uplift of both the basin and its margins.