Climate Evolution Since Late Mid-Pleistoncene On The North Of Tengger Desert

Quaternary’s climate change is very important to the study of the future globalclimate, especially the climate of monsoon’s boundary zone in North China because ofits sensitivity to the climate changes. We get sediment samples with high-resolutionfrom the shallow drilling which is at the north of Tengger Desert, and from the sections.Basis of the analysis on magnetic susceptibility, granularity and pollen records,with OSL age determination test, the climate evolution from the late Pleistocene at thenorth of Tengger Desert can be divided into5stages as follows:1. The late part of Middle Pleistocene (145.1-138.9ka B.P.). Cold and dry,hydrodynamic conditions was not stable, and a large number of shrubs existed.2. Early Late Pleistocene (138.9-125.1ka B.P.). Warm and dry, the lake narrowed,the vegetation was dominated by herbs, classic desert steppe. There might be a shorttime dry event at the late part of this period.3. The late part of Late Pleistocene (125.1-about50ka B.P.). Warm and less dry,the lake expanded, the climate began to turn wet, desert steppe.4. The end of Late Pleistocene (about50ka-14.2ka B.P.). Cool and dry, the lakeexpanded, variety of vegetation types, the cool environment at upstream brought asignificant increase of percentage of Picea pollen. This period matches the high waterlevel period of Zhuye Lake in MIS3.5. To the Holocene till now (14.2-0ka B.P.). Climate fluctuation stage, the climateturned to cold and dry quickly at first, then getting warm and wet. A dry event occurredat this period. The main trend of the climate after the middle Holocene was drying. Thelake began to dry up.The climate evolution of study area is matched with previous studies and the globalclimate background, it also has Particularity in many respects. And because theconclusion depends on the way of sample handling and personal understanding to thedata, there may be some other opinions about the climate evolution.