Dynamics of iron and calcium carbonate redistribution and palaeohydrology in middle Eocene alluvial paleosols of the southeast Ebro Basin margin (Catalonia, northeast Spain)

Abstract

Abstract Paleosols in the alluvial middle Eocene of the Ebro Basin exhibit both the redistribution of iron (groundwater and surface-water gley) and calcium carbonate. The hydrological dynamics are reconstructed through gley features and location of carbonate accumulation. Together, these allow a sophisticated analysis of the (seasonal) palaeohydrology of ancient sedimentary environments. This analysis is performed on paleosols developed in marginal and distal floodplain and delta plain deposits derived from the southeast Ebro Basin margin. The most proximal part of the floodplain sediments had moderate, mainly vadose calcite redistribution with surface-water gleying, and fairly deep groundwater. The more distal sediments have stronger calcite redistribution, both of vadose and surface-water gley environments. These were frequently overprinted by groundwater-related calcite, indicating shallow and fluctuating groundwater. In the most distal alluvial sediments, both calcite redistribution and further soil formation were weak, while groundwater was shallow.