Résumé
We measured planktonic foraminifer stable isotopes in samples from Integrated Ocean Drilling Program Hole U1322B in the northern Gulf of Mexico. Among the 97 samples measured, 35 lie in sediment intervals visibly affected by turbidites and 12 are considered affected either by freshwater discharges or by diagenetic overprinting across boundaries between slumped and in situ sediment intervals. Samples affected by freshwater show very light delta (super 18) O values, whereas those with sudden delta (super 18) O increases are likely influenced by diagenesis. The remaining 50 measurements appear to represent true hemipelagic delta (super 18) O records useful for establishing a preliminary oxygen isotopic stratigraphy for the site. Comparison between isotopic results from Hole U1322B and other similar records from the region indicates that the sediment sequence recovered in Hole U1322B was mainly deposited during marine isotopic Stages (MIS) 1, 2, 3, and 4, separable at 23 (MIS 1/2), 89, and 200 meters below seafloor (MIS 3/4), respectively.