The Paleoclimate Records of Nabkhas Around Ebinur Lake in Northern Xinjiang Since Last Glaciation
|School||Xinjiang Normal University|
|Keywords||nabkha climatic revolution Holocene Last Glaciation Ebinur Lake|
Ebinur Lake is a typical and enclosed extinct rump lake, which located in the inland of Asia and Europe mainland.It is sensitive and fragile to the globle and regional climate change.This article is aimed to make a primary research on climatic environment and evolution regulation since Last Glaciation in Ebinur Lake, Applied the method of eolian geomorphology and Quaternary geology, based on nabkhas around Ebinur lake, investigated the morphological character、types、distribution、sedimentary structure of Nabkha selected several typical sand hill section for systematical sampling and testing and analyzing, combined historical documentaries as well as observational records of modern meteorological phenomenon since Last Glaciation,and it based on OSL dating method of sand of storm layer in nabkhas. It also comprehensively analyzed developmental phrase of lake shore terrace as well as deposit phrase of lake shore shallow shoal. The data that employed in this article are mainly concentrated on two periods:Last Glaciation and late Holocene , as lack of sand of storm layer of OSL dating method in early and middle period of Holocene(9000-5000 years up to now)the main researching achievements are as follows:(1)Ebinur Lake, and its surrounding areas not only possessed relict nabkhas that experienced more than 10,000 years’development,and now they are suffering from deflation slowly,but also active ones that experienced more than several hundred or decade years’of development, and still keep active. The developmental phrases of nabkhas around Ebinur Lake are mainly concentrated on two periods: Last Glaciation and the late Holocene. Most sand drift in Last Glaciation were suffered from severe deflation, only those deflation relicts were left to be bases of shrub sand drift development in late Holocene, the development of nabkhas in late Holocene was under a cold and wet circumstance during neoglaciation and little ice age.(2)Researching area’s climate change since late glacial age, particularly the regional temperature change was coordinated with global climate change, which indicates that the researching area responses to global change,it is driven by the solar radiation change.But the regional precipitation or relative moisture change owns obvious regional characteristics, namely, it is quite wet in Last Glaciation and the late Holocene, however, during great warm period, the precipitation or relative moisture is quite low in the early or middle Holocene.(3)Making a comprehensive comparison and analysis, such as based on concentric distribution time-interval of sand storm layer in nabkhas、the changes of Ebinur Lake depth、developmental age of lake shore terrace、the characteristics of changes of lake shore deposit, the characteristics of climate changes in Ebinur Lake since late glacial age,it is based to sand of storm layer of OSLdating material as well as the expremental results of representative index.Around 18000-9000, the climate was cold and wet, the temperature picked up obviously amid severe fluctuation, 9000-4000, the climate was droughty, the wind was strong, it is quite ordinary to see deflation intermit sedimentary structure, from the year 4000 to now, the climate is cold and wet, and nabkhas generally enjoins continued development, represented by climate change mode of subtropical westerlies.