An absolutely dated record of climate change over the last three glacial--interglacial cycles from Chinese loess deposits.

Chinese loess-paleosol sequences have long been regarded as the continental counterpart of deep-sea sediments in terms of their record of the Quaternary glacial--interglacial cycles. However, absolute chronologies for loess-paleosol sequences older than ca. 130 ka on the Chinese Loess Plateau are scarce. We conducted the first high-resolution luminescence dating, extending back to 350 ka, of the classical Luochuan loess section of the central Chinese Loess Plateau. Bacon age-depth modeling of the luminescence ages was used to obtain an age framework. The results indicate that on orbital timescales, loess accumulation at Luochuan was continuous over the last three glacial--interglacial cycles. The new age framework resolves discrepancies between orbitally tuned age models at several boundaries and provides new evidence supporting the reassignment of the Marine Isotope Stage 8/9 boundary age from 300 ka to ca. 280 ka. Our results also suggest that published astronomical timescales for the loess deposits of the Chinese Loess Plateau over the last ~2.6 m.y. are probably broadly reliable, as are the related regional and global climatic interpretations. [ABSTRACT FROM AUTHOR]