TY - GEN
T1 - Architecture and depositional development of the Eocene deep-marine Morillo and Coscojuela Formations, Ainsa Basin, Spain – Implications for slope erosion and collapse as a result of flow deflection
AU - Pohl, F.
AU - McCann, Tom
PY - 2014/9
Y1 - 2014/9
N2 - The Ainsa Basin is the central part of the deep marine Graus/Tremp – Ainsa – Jaca Basin complex in N Spain. Formed as a result of thrust activity related to the evolution of the Pyrenees the Ainsa Basin contains a 4000 m thick, Eocene age deep-marine succession of the San Vicente Group that comprises individual sandbodies (up to 24), separated by marls (Mutti et al., 1984; Sutcliffe and Pickering, 2009). The depositional record within the basin is a complex one, and neither the precise number of preserved deep-marine channel sandbodies present nor the actual depositional processes involved, are always clear (e.g. Das Gupta and Pickering, 2008; McCann and Arbués, 2012; Labourdette et al., 2008).The aim of the present study is to explore the depositional architecture of one of the deep-marine channel complexes which we consider to be key to our understanding of the late evolution of the depositional succession within the Ainsa Basin. Detailed analysis of nine outcrops (> 900 m sediment profiles) from the Morillo Formation of the San Vicente Group, from the upper part of the basin succession revealed that sediment transport was to the NW. Additionally, a range of environments were recognized including channels, lobes and pelagic units. The overlying Coscojuela Formation, which partly cuts into the Morillo Formation, shows W-directed palaeocurrents in its proximal reaches, with flows being deflected to the N parallel to the basin slope. Destabilisation of the adjacent carbonate platform resulted in significant input of carbonate material into the flow. Thus, the final phases of sedimentation within the Aínsa Basin were more complex than previously suspected probably as a result of a combination of factors, including, tectonic activity resulting in basin narrowing due to anticlinal growth, as well as encroachment and/or destabilisation of the adjacent regional carbonate platforms.
AB - The Ainsa Basin is the central part of the deep marine Graus/Tremp – Ainsa – Jaca Basin complex in N Spain. Formed as a result of thrust activity related to the evolution of the Pyrenees the Ainsa Basin contains a 4000 m thick, Eocene age deep-marine succession of the San Vicente Group that comprises individual sandbodies (up to 24), separated by marls (Mutti et al., 1984; Sutcliffe and Pickering, 2009). The depositional record within the basin is a complex one, and neither the precise number of preserved deep-marine channel sandbodies present nor the actual depositional processes involved, are always clear (e.g. Das Gupta and Pickering, 2008; McCann and Arbués, 2012; Labourdette et al., 2008).The aim of the present study is to explore the depositional architecture of one of the deep-marine channel complexes which we consider to be key to our understanding of the late evolution of the depositional succession within the Ainsa Basin. Detailed analysis of nine outcrops (> 900 m sediment profiles) from the Morillo Formation of the San Vicente Group, from the upper part of the basin succession revealed that sediment transport was to the NW. Additionally, a range of environments were recognized including channels, lobes and pelagic units. The overlying Coscojuela Formation, which partly cuts into the Morillo Formation, shows W-directed palaeocurrents in its proximal reaches, with flows being deflected to the N parallel to the basin slope. Destabilisation of the adjacent carbonate platform resulted in significant input of carbonate material into the flow. Thus, the final phases of sedimentation within the Aínsa Basin were more complex than previously suspected probably as a result of a combination of factors, including, tectonic activity resulting in basin narrowing due to anticlinal growth, as well as encroachment and/or destabilisation of the adjacent regional carbonate platforms.
M3 - Conference contribution
BT - GeoFrankfurt 2014, Frankfurt, Germany.
ER -
