Paleomagnetism of late Quaternary marine sediments from Santa Catalina Basin, California continental borderland

Abstract

Paleomagnetic secular variation (PSV) records have been recovered from three marine sediment cores from Santa Catalina basin, California continental borderland, in order to more accurately date these late Quaternary sediments. The PSV records are not high in resolution due to low sedimentation rates coupled with a 3‐cm sampling interval and some inherent smoothing of the PSV signal during remanence lock‐in. However, the PSV waveforms are sufficiently clear to permit their correlation among the three separate cores. These PSV records can also be correlated with four independent PSV calibration curves from western North America that have detailed radiocarbon age control. The four calibration curves are developed in this paper to improve the dating and regional comparison of PSV records from western North America. The PSV correlations establish time‐depth curves for the three cores which indicate that the sediments are all younger than about 11,000 years B.P. The relative accuracy of the time‐depth curves is approximately 200 years, which represents an order‐of‐magnitude improvement in the chronology of these sediments. Sedimentation rates derived from the three time‐depth curves indicate a constant rate of 20–25 cm/kyr for the last 6700 years throughout Santa Catalina basin, and more variable rates (but constant within each core) of 13–86 cm/kyr prior to 6700 years B.P. In all three cores, the change in sedimentation rate corresponds to a subtle but distinct change in lithology. These changes probably indicate a major shift in paleoceanographic processes within Santa Catalina basin 6700 years B.P.