Tectono-sedimentary evolution within the Tremp, Ainsa and Jaca basins northern Spain
Final Report Abstract
The N/NW-trending Ainsa Basin contains a thick, deep-marine succession comprising individual sandbodies (up to 24), separated by thick marls and arranged into four unconformity-bounded depositional units. Petrological analysis suggested that additional, intra-unit boundaries were also present, and that these marked a changeover from a carbonate-poor to a carbonate-rich succession within the basin succession. At least in terms of the fragments which are present within the sandstone bodies. A stratigraphic study examining the geochemistry of the basin, and examining both the sandstone bodies as well as the intercalated marl units, confirmed the marked increase in carbonate at the time of the transition from the Ainsa sandbody to the Morillo sandbody (both within the San Vicente 3 tectonostratigraphic unit). Examination of both bodies revealed the presence of a sandstone unit which had not been previously recognised (i.e. Coscojuela system), and integrated its evolution into broader changes (both tectonic and depositional) which were taking place within the basin at the time of its deposition. Thus, the Morillo system was redefined as a high energy turbiditic system which evolved over time to a channelized lobe deposition predominated. This is erosively overlain by the Coscojuela system which contains clasts derived from the adjacent carbonate slope possibly as a result of flow defiection. This may have been as a result of flow interaction with the slope itself, resulting in possible slope erosion or destabilisation and partial collapse of the carbonate platform. It is also possible that the change in provenance signalled basin narrowing related to the onset of deltaic sedimentation, and the final closure of the Ainsa Basin.
Publications
- 2012. Deep-marine sandstone provenance, Ainsa Basin, Southern Pyrenees, Spain. Zeitschrift der deutschen Gesellschaft für Geowissenschaften, 185-201
McCann, T. & Arbues, P.
