Detailed paleomagnetic and rock magnetic variability within three high-resolution study intervals from Site 1233
We carried out a detailed rock magnetic and paleomagnetic study of deep-sea sediments from selected intervals of Site 1233 in order to assess whether they contain reproducible evidence for submillennial-scale environmental, climatic, and geomagnetic field variability. Three 1.5-m sediment intervals from oxygen isotope Stages 1, 2, and 3 were sampled using continuous U-channels; replicate sediment sequences were collected from two or three holes in each interval to test for reproducibility. Rock magnetic and paleomagnetic measurements were made at 1-cm intervals. Rock magnetic results identify distinctive centennial (~150-300 yr)- and millennial-scale variability that is probably continuous over the entire Site 1233 record. They also show evidence for intermittent multidecadal-scale rock magnetic variability. The rock magnetic variability allows us to modify the meters composite depth (mcd) correlation in each of the three high-resolution intervals to permit correlations between holes at ~5-cm resolution. Paleomagnetic results indicate that there is also a reproducible pattern of paleomagnetic secular variation at the centennial to millennial scale. The centennial-scale variability is dominated by ~5°-10° oscillations in both inclination and declination with an average interval of ~200-300 yr. Deconvolution studies and paleomagnetic secular variation (PSV) correlations between holes both suggest that the PSVs are real and not caused by similar-scale rock magnetic variability. The paleomagnetic results also document distinctive, larger-amplitude multicentennial- and millennial-scale directional variability that is consistent with preliminary shipboard paleomagnetic studies.
Helmholtz Research Programs > MARCOPOLI (2004-2008) > POL6-Earth climate variability since the Pliocene