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Damped fluctuations in Chinese loess grain size
Author(s) -
Xiong S. F.,
Ding Z. L.,
Jiang W. Y.,
Yang S. L.,
Liu T. S.
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2003gl018187
Subject(s) - loess , geology , paleosol , pleistocene , isotopes of oxygen , aeolian processes , interglacial , glacial period , grain size , paleontology , paleoclimatology , climate change , early pleistocene , plateau (mathematics) , tectonic uplift , physical geography , climatology , geomorphology , tectonics , oceanography , geochemistry , geography , mathematical analysis , mathematics
The sediment record of the loess‐paleosol sequence in the Chinese Loess Plateau reveals a strong relationship between grain size fluctuations and glacial‐interglacial cycles documented by marine oxygen isotope variations. However, on tectonic time scales, differences between the loess‐paleosol grain size record and the marine oxygen isotope record can be identified. Analytical results from the Baishui, Jingchuan and Lingtai sections show that the grain size of eolian loess, superimposed on a coarsening trend, has two abrupt shifts at about 2.55 and 1.25 Ma, which are followed by significantly damped fluctuations in grain size. This is different from the global oxygen isotope record which demonstrates higher amplitude variations since the late Pliocene‐early Pleistocene and lacks analogs of the abrupt shifts. We propose that the progressive uplift of the Tibetan plateau may have forced the regional environmental system across two thresholds at the late Pliocene‐early Pleistocene and the middle Pleistocene, respectively, inducing two pulses of climatic and environmental changes over north‐western China which are superimposed on the global cooling trend and orbital climate changes.