| 22-Ma eolian deposits in China and long-term climate changes |
| |
| 作者姓名： | Zhengtang GUO Qingzhen HAO William Ruddiman Shuzhen PENG Tungsheng LIU |
| |
| 作者单位： | [1]Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China [2]Institute of Earth Environment, Chinese Academy of Sciences, Xi＇an 710075, China [3]Department of Environmental Science, Clark Hall University of Virginia, Charlottesville, Virginia 22903, USA |
| |
| 摘 要： | The history of eolian dust deposition in northern China has been traced back to 22 million years ago （Ma） and the combination of different eolian formations provides a nearly continuous terrestrial climate record since the early Neogene. The spatial distribution of environmental indicators define a roughly EW zonal climate pattern in Asia throughout the Paleogene, attributable to a circulation pattern dominated by a Planetary Wind System （PWS）. A major rearrangement occurred near the Miocene/Oligocene boundary, characterized by a replacement of the zonal PWS by a monsoon circulation similar to that of the present day. This event is also marked by the onset of loess deposition in northern China. The Asian summer monsoon was likely rather weak during the Paleogene. The loess deposition and formation of numerous well-developed paleosols since the Early Miocene indicate that the following features of the modem-day circulation already existed 22 Ma ago： sizeable deserts in the Asian inlands as dust sources, the winter monsoon as dust carrier, and an energetic summer monsoon as a supply of moisture. Uplift of the Himalayan-Tibetan complex and changes in land-sea distribution were likely responsible for these joint changes in circulation and aridity. From 22 to 6 Ma, loess accumulation rates were much lower, suggesting moderate levels of ar/dity and winter monsoon strength. Evolution of the aridity was not strongly correlative with the cooling trends indicated by marine oxygen isotope records, suggesting a smaller impact of global cooling on drying of the Asian interior during this time interval. However, the general aridification history since about 6 Ma matches the ongoing high-latitude cooling and the consequent expansion of Arctic sea-ice/ice sheets. Some increases in aridification also coincide with proposed uplift of portions of the Tibetan Plateau.
|
| 关 键 词： | 黄土 古土壤 荒漠化 新生代 土壤 |
22-Ma eolian deposits in China and long-term climate changes |
| |
| Zhengtang GUO Qingzhen HAO William Ruddiman Shuzhen PENG Tungsheng LIU.22-Ma eolian deposits in China and long-term climate changes[J].Chinese Journal of Geochemistry,2006,25(B08):281-281. |
| |
| Abstract: | |
| |
| Keywords: | loess paleosol Asian monsoon Cenozoic desertification |
| 本文献已被 维普 等数据库收录！ |
|
