Calibrating the Consequences of Eocene Hyperthermal Events: A Bathyal Case-Study from the Western Tethys

The gradual warming trend of the early Paleogene culminated in the early Eocene Climatic Optimum (EECO; between 53.26 - 49.14 Ma), and it was followed by gradual cooling. Superimposed on these gradual trends, multiple hytherthermal events have been identified globally as perturbations of the global carbon cycle associated with rapid warming. Their different duration, magnitude and rate of warming led to different responses in sedimentation patterns and ecosystems. The micropaleontological (benthic foraminifera) and geochemical (stable isotopes, multi-elemental analysis) response to early Eocene hyperthermals is analysed in the lower bathyal Alamedilla section, in the western Tethys (Betic Cordilleras, SE Spain). The Paleocene-Eocene Thermal Maximum (PETM), the Eocene Thermal Maximum-3 (ETM3, also known as the K event, 52.4 Ma), and possibly the L event have been identified at Alamedilla. These events are marked by negative excursions in bulk sediment carbon and oxygen isotopes, decreased %CaCO3, increased Mg/Ca ratios, and changes in benthic foraminiferal assemblages. Only the PETM, the largest hyperthermal, caused significant extinction among benthic foraminifera, while smaller hyperhermals triggered assemblage changes. The consequences of these minor hyperthermal events vs. the PETM on deep-sea biota at the same site will allow us to analyse the possible relationship between the magnitude of each event and its consequences, with implications to predict the consequences of rapid warming events.