A high-resolution micromorphological record of changing landscapes and climates on the western Loess Plateau of China during oxygen isotope stage 5

作者：Kemp RA^*; Derbyshire E; Meng XM

来源：Palaeogeography, Palaeoclimatology, Palaeoecology, 2001, 170(1-2): 157-169.

DOI：10.1016/S0031-0182(01)00236-X

• micromorphology
• palaeoclimate
• Loess
• palaeosols

The micromorphological characteristics of a continuous set of black samples from 24-38 m depth in a well section on Jiuzhoutai Mountain, Lanzhou, China, are described. The shape of the magnetic susceptibility curve, together with previously published radiocarbon, luminescence and geomagnetic dates, indicates that this sample set encompasses the whole of the last interglacial (S1) palaeosol complex, and extends into the overlying and underlying loess (L1 and L2) units. Seven pedosedimentary units are recognised on the basis of trends in the bulk properties and the key micromorphological indicators (excrements, textural concentrations, shell fragments, and calcite and gypsum features). High rates of loess deposition, with significant cryogenic activity, gypsum precipitation and only weak bioturbation, characterised Oxygen Isotope Stage (OIS) 6 and OIS 4 at Lanzhou. Depositional rates were moderately high in OIS 5d and 5b, with slightly higher bioturbation and no significant cryogenesis or gypsum precipitation. OIS 5e, 5c and 5a were marked by low rates of accretion, more extensive bioturbation and limited leaching. This reconstruction reflects the pedosedimentary responses to fluctuating dominances of monsoonal controls during this period of global climatic change. Comparison of earlier micromorphological results from sites to west and east of Lanzhou along a dry to humid climatic gradient indicate a clear regional pattern with reduced loess accumulation rates and enhanced bioturbation and leaching in the humid east (Tianshui and Xian). Clay translocation occurred only in OIS 5e at Xian, the warmest and most humid site on the transect.

• 出版日期2001-6-1