Texas A&M University, United States

During Ocean Drilling Program Leg 202, detailed shipboard paleomagnetic measurements at Sites 1233 and 1234 identified a reproducible high-resolution record of paleomagnetic secular variation (PSV) at each site. These records also contained evidence for three magnetic field excursions. This paper summarizes the complete paleomagnetic record from Site 1233 and the paleomagnetic record for the uppermost 30 meters from Site 1234. We also establish a detailed PSV correlation between the two sites, located approximately 500 km apart. Twenty-seven accelerator mass spectrometry radiocarbon dates permit us to develop time-depth plots and detailed PSV time series for the last approximately 50,000 yr at both sites. Based on our chronostratigraphy, the most recent excursions occur at approximately 35,000 cal. yr before present (BP) (Excursion 3alpha ) and approximately 41,000 cal. yr BP (Excursion 3beta ). The excursions were named for the oxygen isotope stages within which they occur. These two excursions are not significantly different in age from the Mono Lake Excursion and Laschamp Excursion. A third, older excursion, which has not yet been adequately dated, also occurs at Site 1233.