Terrigenous Eolian Grain-Size through the Initial Eocene Thermal Maximum: Results from the South Atlantic (ODP Site 1263) and North Pacific (ODP Site 1209)

The grain-size of terrigenous material chemically extracted from open-ocean marine sediments has been used as a proxy for zonal wind strength and atmospheric circulation intensity. The several available coarse temporal resolution eolian grain-size records through the early Paleogene all depict a general fining through the Paleocene Eocene (P-E) transition. This finding has been interpreted to represent a profound global decline in the intensity of atmospheric circulation that coincided with rising Earth surface temperatures. However, the P-E transition is complicated, comprising both long-term (e.g. general transition from the relatively cool Late Paleocene to the warmer Early Eocene Climatic Optimum) and rapid fluctuations (e.g. the Initial Eocene Thermal Maximum and subsequent ancillary transient hyperthemals) in global climate, implying a need for high-temporal resolution early Paleogene records of eolian grain-size from various locations. We present preliminary work from ODP Sites 1263 and 1267 (Walvis Ridge, South Atlantic) that indicate the applicability of Site 1263 sediments for eolian analysis as well as initial Site 1263 and Site 1209 (Shatsky Rise, North Atlantic) eolian grain-size results through the IETM.