Stable isotopic signatures of Tertiary lake carbonates, eastern Ebro Basin, Spain
Abstract The Tertiary Ebro Basin, Spain, was a region of internal drainage fed by rivers emanating from the fringing Pyrenees, Catalanides and Iberian chains. The stable isotopic composition of bulk carbonates deposited in diverse late Eocene to Oligocene lakes within the eastern part of this endorheic region are investigated. Carbon and oxygen isotopes fall into several distinct hydrographic provinces which are partly palaeogeographical and partly biostratigraphical. The isotopic signatures of the lake carbonates primarily reflect the nature of the river input (duration, seasonality, catchment geology) and autochthonous processes within the lake (biological productivity, evaporation) but diagenetic changes may further complicate interpretations. Seasonal changes in precipitation rates are picked out by light-dark variations in single lithological cycles.