Evidence for the Kamikatsura and Santa Rosa excursions recorded in eolian deposits from the southern Chinese Loess Plateau

A detailed paleomagnetic investigation of a loess-paleosol sequence in Baoji, southern Chinese Loess Plateau, reveals two distinct geomagnetic excursions accompanied by inferred relative paleointensity minima in the late Matuyama Chron. Rock magnetic experiments demonstrate that the sediments of the excursion intervals, in loess unit L9, have the same magnetic properties as those from surrounding normal and reversed polarity intervals. Assuming constant sedimentation rate between the Jaramillo-Matuyama and Matuyama-Brunhes magnetic polarity boundaries, the midpoint ages and durations for these two excursions are estimated at 0.89 Ma and 16 kyr, and 0.92 Ma and 7 kyr, respectively. In addition, these two events are separated by an interval with fully reversed polarity that had a duration of 16 kyr. These estimates are supported by paleoclimatologically inferred age constraints. The two excursions are probably correlated with the Kamikatsura and Santa Rosa excursions, respectively.