全部 标题 作者
关键词 摘要

OALib Journal期刊
ISSN: 2333-9721
费用:99美元

查看量下载量

相关文章

更多...

EVOLUTION OF NATURAL ENVIRONMENT IN CHINA SINCE THE LAST GLACIAL PERIOD AND ITS POSITION IN THE GLOBAL CHANGE
末次冰期以来中国自然环境变迁及其与全球变化的关系

Keywords: 冰期,更新世,全球变化,气候,变化

Full-Text   Cite this paper   Add to My Lib

Abstract:

At the acme of the last glacial period,glaciers in western China obviously advanced andwere 2—5 times longer than modern ones.In southeastern Qinghai-Xizang Plateau and west-ern Sichuan Province,ice caps were formed locally,and glaciers were 5—10 times longerthan that at present.Snowlines at that time were lower than those of today:100—500m lowerin the hinterland of Qinghai-Xizang Plateau,600—800m lower in the Tianshan Mountainsand Altay Mountains,600—800m lower in the Qilianshan Mountains,400—600m lower inthe Hengduangshan Mountains,300—450m lower at the north slope of the Himalayan,400—1000m lower in the Nyaninqentanglha Range,600—1000m lower in the western Kunlun-shan Mountains and 900—1080m lower in the Karakorumshan Mountains.The lower limit ofthe permafrost area on the north margin of Qinghai-Xizang Plateau dropped at that time tothe elevation of 2400m,about 2000m lower than that at present.The southern boundary ofthe permafrost area in the plain-hilly region in the east was near 33°20′—33°40′N,shiftingsouthward for 16—17 degrees of latitude as compared with the modern one,In the sporo-pollen assemblage of the strata,the coniferous forest stage dominated by Picea and Abies rep-resents a relatively warm stage of the glacial period,and the subsequent herb stage reflectsthe features of the climax of the glacial period.During the late glacial period the climatic oscillation was not remarkable in China,buta noticeable event (i.e.the abrupt fall of the sea level) took place at 10800 a B.P.At 8000—6000 a B.P.,a high-temperature event occurred,marking the stage of vigorous developmentfor agriculture,animal husbandry and culture,and the sea level was 2—5m higher than thatat present.At 5600—5000 a B.P.,a short period of low temperature appeared,leading to thesudden advance of the retreating glac(?)ers and the fallback of the sea level.Thereafter theclimate on the whole turned cold.The occurrence of a Neoglaciation period at 3000 a B.P.resulted in the multistage advance of glaciers in western China.A Little Ice Age period inthe 16th—19th century,i.e.the cold period of the Ming and Qing Dynasties (1550—1850),represented the coldest time since 5000 a B.P.,during which the advance of glaciers left threeramparts of terminal moraine.The migration and even extinction of some mammals in eastern China were the result ofa combination of natural environment changes and human activities.The evolution of natural environment in China since the last glacial period is part ofthe global change,but it has characteristics of its own.The accidents in the environmentalevolution mostly happened on the background of cosmic variation,for instance,the supernovaoutburst,the change in intensity of solar activity and the alteration of parameters of Earthrevolution orbit.

Full-Text

Contact Us

service@oalib.com

QQ:3279437679

WhatsApp +8615387084133