10Be records of the Matuyama-Brunhes polarity reversal in the northeastern Chinese loess Plateau

Abstract

The precise stratigraphic position of the Matuyama-Brunhes (M-B) geomagnetic polarity reversal within Chinese loess sequences and its asynchrony with marine records have been long debated. This uncertainty limits our ability to establish a reliable geochronology for Chinese loess sequences and precise land-sea correlation of paleoclimate records. Here we present the high-resolution ¹⁰Be results across the M-B boundary for the Fanshan loess profile in the northeastern Chinese Loess Plateau, for which previous high-stratigraphic-resolution paleomagnetic measurements failed to detect the exact position of the M-B boundary. A major enhancement of the ¹⁰Be content (representing an increased atmospheric ¹⁰Be production rate) in the upper part of paleosol S7 unambiguously represents the M-B boundary. The estimated age of 773 ± 3 ka for this boundary is consistent with ¹⁰Be-inferred age of the M-B boundary in the EPICA Dome C ice core, marine sediment cores, and in the classic Luochuan loess sequence. These findings confirm the robustness of ¹⁰Be in constraining geomagnetic reversals in Chinese loess sequences, after the effects of climate on ¹⁰Be records have been successfully removed.