Expedition 303 summary

Abstract

Expedition 303 was designed to sample and study strategic sites that record components of North Atlantic Pliocene–Quaternary climate, including the composition and structure of surface or bottom waters and detrital-layer stratigraphy indicative of ice sheet instability. The sites are distributed from the mouth of the Labrador Sea (Eirik Drift and Orphan Knoll) to the central Atlantic in the region of the Charlie Gibbs Fracture Zone. The sites have important climate or paleoceanographic records, adequate sedimentation rates in the 5–20 cm/k.y. range for high-resolution studies, and the potential for stratigraphies based on relative geomagnetic paleointensity and oxygen isotope data. The sites contain distinct records of millennial-scale environmental variability (in terms of ice sheet–ocean interactions, deep circulation changes, or sea-surface conditions). They provide the requirements for developing millennial-scale stratigraphies (through geomagnetic paleointensity, oxygen isotopes, microfossils, and regional environmental patterns). They also document the details of geomagnetic field behavior over the last few million years. The ultimate objective is to generate a chronostratigraphic template for North Atlantic climate proxies and to allow their correlation at a sub-Milankovitch scale and their export to other parts of the globe. The lack of such a chronostratigraphic template has been a major obstacle to the study of sub-Milankovitch–scale climate history. A total of 4656 m of high-quality core was recovered from sites with mean sedimentation rates reaching 20 cm/k.y. In the coming years, we expect research on these cores to break new ground in Late Pliocene–Quaternary paleoclimatology, paleoceanography, and paleomagnetism.