Siliciclastic sediment volumes and rates of the North Pyrenean retro‐foreland basin. (30th March 2022) - Ortiz, Alexandre
Abstract: Sediment accumulation rates in foreland basins result from a complex interplay between surface and deep processes in both the exhumed relief domain and sedimentary basins. The growth and decay of a mountain belt during orogenic and post‐orogenic phases have been largely studied, thanks to thermochronological and structural studies. The sedimentary response of the orogenic phases in the preserved sediments of the surrounding basins is well known in terms of sedimentary filling patterns and architecture, but much less better quantified. Here, we performed a measurement of the siliciclastic sediment volumes of the Pyrenean retro‐foreland basin—the Aquitaine Basin and the Bay of Biscay during Cenozoic times—for a better understanding of the erosion and the sediment transfer and deposition during the convergence (syn‐orogenic) to post‐convergence (post‐orogenic) periods of the Pyrenees Mountain. The measurement of the compacted siliciclastic sediment is based on sediment thickness (isopach) maps of known lithologies, derived from the interpretation of 40, 000 kms of seismic profiles. Thanks to the siliciclastic sediment volumes quantification and a well‐known retro‐foreland basin tectono‐sedimentary evolution, we bring quantitative results as: The amount of preserved sediments is of 51, 500 ± 16, 800 km 3 for the Cenozoic. The siliciclastic sediment rate curve during Cenozoic shows two major increases around 26.0 and 2.5 Ma. The 26.0 Ma increase is clearly related to the erosion of the Pyrenees of tectonic origin. The major 2.5 Ma one would be mainly related to a climatic forcing. The mass balance between the Aquitaine Platform and the deepest domains changes through time in favour of the deep domain. This might be explained by the ratio between subsidence that created accommodation space and the sediments feed by the mountain belt and stored in the Aquitaine Platform. Abstract : We performed a measurement of the siliciclastic sediment volumes of the Pyrenean retro‐foreland basin—the Aquitaine Basin and the Bay of Biscay during Cenozoic times—for a better understanding of the erosion and the sediment transfer and deposition during the convergence (syn‐orogenic) to post‐convergence (post‐orogenic) periods of the Pyrenees Mountain.