Notícies

Publicació de l'article "Dating the northern deposits of the Ebro foreland basin; implications for the kinematics of the SW Pyrenean front"

La Dra. Bet Beaumud, responsable de la Unitat de Paleomagnetisme dels CCiTUB i de l'Institut de Ciències de la Terra-Jaume Almera (ICTJA-CSIC), ha participat en la publicació de l’article "Dating the northern deposits of the Ebro foreland basin; implications for the kinematics of the SW Pyrenean front.” a la revista Tectonophysics. Aquest article és el resultat d'una col·laboració entre la Unitat de Paleomagnetisme, el professor M. Garcès del Departament de Dinàmica de la Terra i de l'Oceà de la Universitat de Barcelona, i investigadors de la Universitat Autònoma de Madrid, la Universitat Autònoma de Barcelona, la Universitat de Zaragoza, l'Institut Universitari d'Investigació en Ciencies Ambientals d'Aragó i l'Institut Geológic i Miner d'Espanya.

El resum de l'article és el següent:

"Dating the sedimentary infill of the northern margin of the Ebro foreland basin informs about the orogen-basin evolution. A magnetostratigraphic section of ~5 km-thick combines new magnetostratigraphic results from the syntectonic alluvial Uncastillo Fm (Upper Oligocene-Lower Miocene, 1 km-thick, the Fuencalderas section) with previous (3.3 km-thick) and new (0.7 km-thick) magnetostratigraphic data from the underlying fluvial Campodarbe Fm (Luesia and San Marzal sections, Eocene-Oligocene). This composite section allows dating the entire basin infill in this sector, therefore bracketing the timing of the deformation in the southern margin of the Pyrenees after considering previous kinematic studies. Deformation recorded by the continental deposits spans from syn-Gavarnie nappe activity (Broto and Fiscal basement thrust sheets) from 31.3 to 24.55 Ma, Rupelian-Chattian (Oligocene) to the syn-Guarga thrust activity, from 24.55 to 21.2 Ma Chattian-Aquitanian (Oligocene-Miocene). The Accumulation rates vary from ca. 22 to ca. 39 cm/kyr between the genetic stratigraphic units in the Uncastillo Fm through the section. These rates are close to those of the underlying deposits of the Campodarbe Fm (average of ca. 36 cm/kyr). Deformation for the latest Pyrenean front (syn-Guarga thrust) is younger than previously assigned in ~5.4. ~1.5 and ~1.1 Myr of the beginning of the Punta Común thrust sheet (from 29.4 Ma to 24 Ma), Lower Riglos thrust sheet system (from 24 to 22.5 Ma) and the Upper Riglos thrust system (22.5 to 21.4 Ma) respectively. Other significant changes in accumulation rate and its derivative also indicate variations in the tectonic activity ca. 33 and 28 Ma. "

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