Full-Text Search:
Home|Journal Papers|About CNKI|User Service|FAQ|Contact Us|中文
《Earth Science(Journal of China University of Geosciences)》 2007-05
Add to Favorite Get Latest Update

Environmental Evolution of Late Pleistocene Loess Deposits at Lintao County,Gansu Province

ZENG Fang-ming1, XIANG Shu-yuan1, LU Yu-lin2, MA Xin-min3, LU Jing-fang1 1.Faculty of Earth Sciences,China University of Geosciences,Wuhan 430074,China 2.Institute of Geology and Geophysics,Chinese Academic of Sciences,Beijing 100029,China 3.Northwest Branch of the Research Institute of Petroleum Exploration and Development,PetroChina,Lanzhou 730020,China  
According to the comprehensive analysis of granularity and magnetic susceptibility of late Pleistocene loess-paleosol sequence at Tawan, Lintao County, Gansu Province, the climate change in this area can be divided into seven phases. (1) 1-8.5 m above the bottom (92.4-78.8 kaBP): the average value of particle diameter and magnetic susceptibility was 24.42 μm and 716.8×10-6 SI, and the annual average temperature and precipitation reached to 7.8 ℃ and 500 mm, being the highest of the seven phases, indicating warm and wet climate. (2) 8.5-14.8 m above the bottom (78.8-65.3 kaBP): the average value of particle diameter and magnetic susceptibility was 26.83 μm and 442.3×10-6 SI, and the annual average of temperature and precipitation was about 5.2 ℃ and 370 mm. The climate was tepid and dry. (3) 14.8-20.3 m above the bottom (65.3-57.3 kaBP): the mean of particle diameter and magnetic susceptibility was 25.94 μm and 320.7×10-6 SI, and the annual average temperature and precipitation was about 3.5 ℃ and 280 mm. The climate changed to be mild-dry and slightly cool. (4) 20.3-24.9 m above the bottom (57.3-47.7 kaBP): the average value of particle diameter and magnetic susceptibility was 25.23 μm and 516.4×10-6SI, and the annual average temperature and precipitation reached 6.0 ℃and 410 mm. It was mild-dry and slightly wet. (5) 24.9-29.4 m above the bottom (47.7-40.9 kaBP): the mean of particle diameter and susceptibility was 25.46 μm and 299.4×10-6 SI, and the annual average temperature and precipitation was 3.1 ℃ and 270 mm. The climate was mild-dry and slightly cool. (6) 29.4-34.2 m above the bottom (40.9-32.4 kaBP): the average value of particle diameter and susceptibility was 21.46 μm and 405.5×10-6 SI, and the annual average temperature and precipitation was about 4.7 ℃ and 350 mm. It was mild-dry and slightly wet. (7) 34.2-39 m above the bottom (after 32.4 kaBP): the average value of particle diameter and susceptibility was 188.89 μm and 381.1×10-6 SI, and the annual average temperature and precipitation was about 4.4 ℃ and 330 mm. The climate was warm and dry. There shows a high comparability between these climate changes in the studied area and the regional environmental evolution. PhaseⅠcorresponds to the warm MIS(marine isotope stage)5 ; PhaseⅡandⅢ correspond to the cooling MIS4; Phase Ⅳ,Ⅴand Ⅵ correspond to the warm MIS3 ; Phase Ⅶ corresponds to the cooling MIS2. Compared with adjacent areas, like Jiuzhoutai in Lanzhou Province and core RM in Zoige, the climate is obvious warmer and wetter in Linxia during the same period.
【Fund】: 中国地质调查局综合研究项目(No1212010610103);; 中国地质调查局区调项目(No200413000007)
【CateGory Index】: P534.631
Download(CAJ format) Download(PDF format)
CAJViewer7.0 supports all the CNKI file formats; AdobeReader only supports the PDF format.
©2006 Tsinghua Tongfang Knowledge Network Technology Co., Ltd.(Beijing)(TTKN) All rights reserved