A record of the Blake Event during the last interglacial paleosol in the western Loess Plateau of China

Abstract

A high-resolution record of the Blake Event has been obtained from a 40 m well dug in a loess section at Jiuzhoutai in the City of Lanzhou in the western Loess Plateau of China. The paleomagnetic signal is principally carried by magnetite both in loess and paleosols. The Blake Event is located at the boundary between paleosol S1-c of the last interglacial (equivalent to MIS 5e in deep-sea records) and loess L2-2 (MIS 5d), and is characterized by a triple feature consisting of two short reversed intervals separated by a short normal interval. The directional changes are abrupt, as previously revealed in other records, and suggest geocentric dipole field behavior before, after and during the event, but not necessarily during NR or RN transitions. The age and duration of the event are estimated as between 119.97 and 114.47 kyr BP and 5.5 kyr, respectively, from thermoluminescence dating and astronomically tuned climate stratigraphy based on high-resolution magnetic susceptibility.