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Loess and red clay on the Chinese Loess Plateau have produced a detailed history of the East Asia monsoon for the past eight million years. Recently, a well-conserved red clay sequence was discovered at Shilou on the eastern edge of Chinese Loess Plateau, extending the monsoon history back to approximately 11 Ma. By comparing lithologic features, particle size distribution, magnetic susceptibility and deposition rate of Shilou red clay sequence, the paleomonsoon evolution from 11 to 2.6 Ma can be divided into four stages: largely fluctuated stage (11.0-8.0 Ma), relatively strengthened period (8.0-6.5 Ma), extremely changed stage (6.5-4.9 Ma) and further intensified period (4.9-2.6 Ma). The new evidence indicates that variation of paleomonsoon has close relationship with uplifting of the Tibetan Plateau and ongoing global cooling and the consequent expansion of ice sheets during 11.0-2.6 Ma. [ABSTRACT FROM AUTHOR]

Abstract: Older red clay deposits on the Chinese Loess Plateau contain information of early paleomonsoon evolution and tectonic history of the Ordos platform and the Tibetan Plateau. A well-conserved eolian red clay sequence was recently discovered at Shilou, on the Eastern Chinese Loess Plateau. Paleomagnetic measurements demonstrate that polarity zones recorded in the Shilou red clay profile correspond well with polarity zones between C2An.1n and C5n.2n of the GPTS, and the basal age of the study profile is approximately 11.0Ma. Field observation, grain-size frequency distribution and quartz grain morphology suggest a wind-blown origin for this sequence. This indicates that the Eastern Loess Plateau began to accumulate dust deposits at 11Ma ago, implying earlier establishment of the East Asian paleomonsoon probably owing to uplifting of the Tibetan Plateau and ongoing global cooling. It also demonstrates that the Eastern Loess Plateau belonging to the Ordos platform was slowly uplifted and suffered from erosion in the early Neogene, and has no conserved eolian deposits older than 11Ma as in the Western Chinese Loess Plateau. [Copyright &y& Elsevier]