Late Miocene-early Pleistocene paleoclimate history of the Chinese Loess Plateau revealed by remanence unmixing

Abstract

Previous studies show that the Quaternary loess sequence and the late Miocene-Pliocene red clay sequence on the Chinese Loess Plateau (CLP) share similar magnetic properties despite their being deposited under different climate conditions. To solve this paradox, we apply a novel remanence unmixing technique and demonstrate that loess and red clay on the central CLP contain a similar low-coercivity pedogenic component, but their high-coercivity components differ dramatically, reflecting different oxidation and temperature conditions. We infer that temperatures on the Chinese Loess Plateau cooled from the late Miocene to the Quaternary, in a manner similar to sea surface temperature records for the same time interval. This coherency between marine and terrestrial records argues for a CO2 forcing on long-term paleoclimatic variations.