Journal of University of Chinese Academy of Sciences >
Magnetostratigraphy and Sedimentology of the Eolian Deposits Since the Late Miocene in Northern China and the Paleoclimatic Implications
Received date: 2002-02-20
Online published: 2002-03-18
In this study, two thick loess-red clay sequences located at Lingtai and Jingchuan, the Chinese Loess Plateau, are studied with emphases on magnetostratigraphy and sedimentology. Paleomagnetic measurements show that the Jingchuan red clay has a basal age of 8.0 Ma, which is one million years older than the previously studied Lingtai section. Field observations and grain size analyses both suggest an eolian origin of the red clay sediments at Lingtai and Jingchuan, thus extending available records of the eolian deposits in the Loess Plateau from 2.6 Ma back to 7.0～8.0 Ma. Correlation of five red clay sections in the Loess Plateau suggests that the Lingtai red clay sequence has a relatively continuous nature of sedimentation and can be regarded as the type-section of the Tertiary red clay deposits in northern China. On the basis of spatial changes in the grain size of one northwest-southeast loess transect, several semiquantitative models of grain size parameters versus the minimum distance from the source region to depositional areas were developed. According to these models, the estimated southeastern margin of the desert in northern China during the Tertiary red clay development is similar to that of the present Badain Jaran desert. To reconstruct the long-term East-Asia monsoon history from the celebrating eolian red clay-loess deposits, the ratios of CBD-extractable Fe2O3 to totalFe2O3 concentrations in the Lintai red clay-loess sequence, the proxy indicator for the summer monsoon changes, were measured. The LingtaiFe2O3 ratio record indicates that the East-Asia summer monsoon has experienced a non-linear evolution over the past seven million years. The strongest East Asia summer monsoon may occur between 4.1 and 4.8 Ma, which may be causally related to the relatively small ice volume and high global temperature during the early Pliocene.
Key words： loess; red clay; eolian deposits; grain size; paleomonsoon
YANG Shi-Ling , DING Zhong-Li . Magnetostratigraphy and Sedimentology of the Eolian Deposits Since the Late Miocene in Northern China and the Paleoclimatic Implications[J]. Journal of University of Chinese Academy of Sciences, 2002 , 19(2) : 202 -208 . DOI: 10.7523/j.issn.2095-6134.2002.2.019
[1] Liu T S.Loess and the Environment.Beijing :China Ocean Press, 1985。251
[2] Kukla G.Loess Stratigraphy in Central China.Quat Sci Rev, 1987, 6:191～ 219
[3] Ding Z L, Xiong S F, Sun J M, Yang S L, Gu Z Y, Liu T S.Pedostratig raphy and Paleomagnetism of a ～ 7.0 Ma Eolian Loess-red Clay Sequence at Lingtai, Loess Plat eau, North-cen tral China and t he Implications for Paleomonsoon Evolution.Palaeogeogr, Palaeoclimatol,Palaeoecol, 1999, 152 :49 ～ 66
[4] Ding Z L, Yang S L, Hou S S, Wang X, Chen Z, Liu T S.Magnetostratigraphy and Sedimentology of the Jingchuan Red Clay Section and Correlation of the Tertiary Eolian Red Clay Sediments of the Chinese Loess Plat eau.J G eophys Res, 2001, 106 :6399 ～ 6407
[5] Ding Z L, Sun J M, Liu T S, Zhu R X, Yang S L, Guo B.Wind-blown Origin of the Pliocene Red Clay Formation in the Central Loess Plat eau, China.Eart h Planet S ci Let t, 1998, 161 :135 ～ 143
[6] Ding Z L, Sun J M, Yang S L, Liu T S.Preliminary Magnetostratigraphy of a Thick Eolian Red Clay-loess Sequence at Lingtai, the Chi-nese Loess Plat eau.Geophys Res Let t, 1998, 25 :1225 ～ 1228
[7] Sun D H, An Z S, Shaw J, Bloemendal J, Sun Y B.Magnetostratigraphy and Palaeoclimatic Significance of Late Tertiary Aeolian Se-quences in the Chinese Loess Plat eau.Geophys J In t, 1998, 134 :207 ～ 212
[8] Liu X M, Xu T C, Liu T S.T he Chinese Loess in Xifeng, II.A study of Anisotropy of Magnetic Susceptibility of Loess from Xifeng.J Geophys, 1988, 92 :349 ～ 353
[9] Lu H Y, Vandenberghe J, An Z S.Aeolian Origin and Palaeoclimatic Implications of theRed Clay(North China)as Evidenced by Grain-Size Di stribution.J Q uat S ci, 2001, 16 :89 ～ 97
[10] Mo D W, Derbyshire E.The Depositional Environment of the Late Pliocene "Red Clay", Jing-Le Basin, Shanxi Province, China.Sed G eol, 1991, 70 :33 ～ 40
[11] Guo Z T, Peng S Z, Hao Q Z, Biscaye P E, Liu T S.Origin of the Miocene-Pliocene Red-Earth Formation at Xifeng in Northern China and Implicat ions for Paleoenvi ronment s.Palaeogeogr, Palaeoclimat ol, Palaeoecol, 2001, 170 :11 ～ 26
[12] Sun J M, Ding Z L, Liu T S.Desert Distributions during the Glacial Maximum and Climatic Optimum:Example of China.Episodes,1998, 21 :28 ～ 31
[13] YANG Sh-iLing.Magnetostratigraphy andSedimentology of the Eolian Deposits in Northern China Since the Late Miocene:[Ph.D.Dis-sert at ion].Beiji ng :Inst itut e of G eology and G eophysi cs, Chinese A cademy of S ciences, 2001, 169 (in Chinese wi th English abst ract)
[14] YANG Shi-Ling, HOU Sheng-Shan, WANG Xu, CHEN Zhuo, XIONG Shang-Fa, DING Zhong-Li.Completeness and Continuity of the Late Tertiary Red Clay S equence in N orthern China:Evidence f rom t he Correlat ion of M agnetost ratigraphy and Pedost rat igraphy bet ween Jingchuan and Lingtai.Q uat Sci, 2000, 20(5):423～ 434 (in Chinese wit h English abst ract)
[15] Guo Z, Biscaye P, Wei L, Chen X, Peng S, Liu T.Summer Monsoon Variations over the Last 1.2 Ma from the Weathering of Loess-Soil Sequences in China.Geophys Res Let t, 2000, 27 :1751 ～ 1754
[16] Ding Z L, Yang S L, Sun J M, Liu T S.Iron Geochemistry of Loess and Red Clay Deposits in the Chinese Loess Plateau and Implications for Long-Term Asian Monsoon Evolution in the Last 7.0 M a.Earth Planet S ci Lett, 2001, 185 :99 ～ 109
[17] YANG Shi-Ling, DING Zhong-Li.Seven Million-Year Iron Geochemistry Record from a Thick Eolian Red Clay-LoessSequence in Chinese Loess Plateau and the Implications for Paleomonsoon Evolution.Chin SciBull, 2001, 46 :337 ～ 341
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