A revised chronology of the Ripoll Basin (NE Spain). Towards an integrated chronostratigraphy of the south-Pyrenean Foreland.

Although the Cenozoic stratigraphy has been widely studied in the Pyrenees, there are still strategic locations lacking a robust dating. Assessing a detailed chronostratigraphic framework is crucial to understand the processes driving the basin evolution and constitute an essential part of the Source to Sink approach. The Early-Eocene represents a crucial stage of the South Pyrenean foreland basin evolution, during which the emplacement of the Southern Pyrenean thrust units lead to basin partitioning and a diversification of the sediment routing systems. To understand sediment transfer across the Eastern and Central South Pyrenean foreland, fine timelines are needed to assess interbasinal correlations and to decipher the linkage between adjacent sedimentary systems and sub-basins.  Here we applied magnetostratigraphy to the 5km thick sedimentary succession that filled the Ripoll basin, as part of the subsiding south-pyrenean trough, aiming at improving the reliability of the dating achieved by earlier studies (Burbank et al., 1992). An increased sampling resolution of the targeted sections allowed a more refined characterization of the local magnetostratigraphy. Integration with marine (shallow-benthic foraminefera) and continental (charophytes, mammals) biostratigraphic data provided a preferred correlation with the Geomagnetic Polarity Timescale (GPTS) that challenges earlier studies. Implications of the new age model for the thrust-belt kinematics, subsidence and the sedimentary evolution of the basin are discussed.

References :

Burbank, D. W., Puigdefàbregas, C., & Muñoz, J. A. (1992). The chronology of the Eocene tectonic and stratigraphic development of the eastern Pyrenean foreland basin, northeast Spain. Geological Society of America Bulletin,104, 1101–1120.