Tectono-thermal history of an exhumed thrust-sheet-top basin : an example from the south Pyrenean thrust belt
Labaume, Pierre (Université de Montpellier. Laboratoire Géosciences Montpellier)
Meresse, Florian (Université de Montpellier. Laboratoire Géosciences Montpellier)
Jolivet, Marc (Université de Montpellier. Laboratoire Géosciences Montpellier)
Teixell Cácharo, Antonio (Universitat Autònoma de Barcelona. Departament de Geologia)
Lahfid, Abdeltif (Bureau de Recherches Géologiques et Minières)

Data:	2016
Resum:	This paper presents a new balanced structural cross-section of the Jaca thrust-sheet-top basin of the southern Pyrenees combined with paleo-thermometry and apatite fission track (AFT) thermochronology data. The cross-section, based on field data and interpretation of industrial seismic reflection profiles, allows refinement of previous interpretations of the south-directed thrust system, involving the identification of new thrust faults, and of the kinematic relationships between basement and cover thrusts from the middle Eocene to the early Miocene. AFT analysis shows a southward decrease in the level of fission track resetting, from totally reset Paleozoic rocks and lower Eocene turbidites (indicative of heating to Tmax>~120°C), to partially reset middle Eocene turbidites and no/very weak resetting in the upper Eocene-lower Oligocene molasse (Tmax<~60°C). AFT results indicate a late Oligocene-early Miocene cooling event throughout the Axial Zone and Jaca Basin. Paleo-maximum temperatures determined by vitrinite reflectance measurements and Raman spectroscopy of carbonaceous material reach up to ~240°C at the base of the turbidite succession. Inverse modelling of AFT and vitrinite reflectance data with the QTQt software for key samples show compatibility between vitrinite-derived Tmax and the AFT reset level for most of the samples. However, they also suggest that the highest temperatures determined in the lowermost turbidites correspond to a thermal anomaly rather than burial heating, possibly due to fluid circulation during thrust activity. From these results, we propose a new sequential restoration of the south Pyrenean thrust system propagation and related basin evolution.
Ajuts:	Ministerio de Economía y Competitividad CGL2010-15416 Ministerio de Economía y Competitividad CGL2014-54180-P Ministerio de Educación y Ciencia CSD2006-00041
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Publicat a:	Tectonics, Vol. 35, Issue 5 (May 2016) , p. 1280-1313, ISSN 1944-9194

DOI: 10.1002/2016TC004192

34 p, 7.7 MB

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