检索结果-南通市图书馆

Evolution of the North Atlantic Current and Barents Ice Sheet as revealed by grain size populations in the northern Norwegian Sea during the last 60 ka

引用

Acta Oceanologica Sinica 2021年第10期40卷 106-117页

作者： Weiguo Wang Mengwei Zhao Yanguang Liu Min Jiang Chengqiang Wu Yang Liu Third Institute of Oceanography Ministry of Natural ResourcesXiamen 361005China Pilot National Laboratory for Marine Science and Technology(Qingdao) Qingdao 266237China First Institute of Oceanography Ministry of Natural ResourcesQingdao 266061China School of Earth Sciences Lanzhou UniversityLanzhou 730000China

The grain size distribution of bulk sediment samples was decomposed in a core to reconstruct paleoceanographic evolution over the past 60 ka in the northern Norwegian Sea.The results show that sediments consisted of 3–4 grain populations derived from the North Atlantic Current(NAC)and Barents Ice Sheet(BIS).The grain size data suggest three palaeoceanographic evolution stages:(1)an environment affected by BIS and NAC and changed with the interstadial/stadial transition in phase with the Greenland ice-core record at 60–31 ka BP,during which discharge of icebergs and the content of the coarsest population containing ice-rafted debris(IRD)in the sediments increased significantly during stadial,while the fine silt population containing volcanic glasses increased with the enhancement of NAC during the interstadial;(2)an extreme environment controlled by BIS at31–13 ka BP.BIS reached to its maximum at about 31 ka BP and the turbid plumes that formed at the leading edge of BIS contributed to a significant increase in the clayey population in sediments.Icebergs drained into the northern Norwegian Sea with periodical calving of the BIS at 31–19 ka BP.Subsequently,the ablation of the BIS discharged massive floods with clayey sediments and icebergs into the Norwegian Sea at 19–13 ka BP,resulting in a constant increase in clay and IRD in sediments;and(3)a marine environment similar to the present one under the strong influence of NAC following the complete melting of the BIS after 13 ka BP,NAC is the dominant transport agent and no IRD occurred in sediments.The fine silt populations containing volcanic glasses transported by NAC significantly increased.

关键词： Norwegian Sea sediments grain size population North Atlantic Current Barents Ice Sheet paleoceanography last glacial

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A Late Quaternary Climate Record Based on Multi-Proxies Analysis from the Jiaochang Loess Section in the Eastern Tibetan Plateau,China

引用

Acta Geologica Sinica(English Edition) 2007年第6期81卷 1087-1096页

作者： BAI Song TANG Ya WANG Chengshan HUANG Chengmin Department of Environmental Science and Engineering School of Architecture and Environment Sichuan University Chengdu 610065 China University of Geosciences Beijing 100083 China

We compared the stable carbon isotopic records from a loess transect of the Jiaochang in the eastern Tibetan Plateau, spanning the last -21,000 years, with multiproxy data for pedogenesis, including magnetic susceptibility, clay fraction, Fed/Fet ratio, carbonate and total organic carbon content, in order to probe the mechanisms of δ^13C values of organic matter and Late Quaternary climate variations in the eastern Tibetan Plateau. Our results indicate that there is no simple relationship between δ^13C of organic matter and summer monsoon variations. The change in δ^13C values of organic matter （in accordance with the ratios of C3 to C4 plants） results from the interaction among temperature, aridity and atmospheric pCO2 level. Drier climate and lower atmospheric pCO2 level contribute to positive carbon isotopic excursion, while negative carbon isotopic excursion is the result of lower temperature and increased atmospheric pCO2 level. Additionally, our results imply that the Tibetan monsoon may play an important role in climate system in the eastern Tibet Plateau, which specifically reflects frequently changing climate in that area. The results provide new insights into the forcing mechanisms on both the δ^13C values of organic matter and the local climate system.

关键词： eastern Tibetan Plateau Jiaochang loess carbon isotope last glacial Late Quaternary

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Aeolian Facies Belts in the Taklimakan Desert

引用

Acta Geologica Sinica(English Edition) 1995年第3期69卷 317-328页

作者： Li Baosheng, Dong Guangrong, Zhang Jiasheng, Li Sen,Jin Heling, Chen Huizhong, Wen Xiangle, Wang Yao, Lanzhou Desert Research Institute, Chinese Academy of Sciences, Lamhou, Gansuand Zhu YizhiXi’an Open Laboratory of Loess and Quaternary Geology, Chinese Academy of Sciences, Xi’an, Gansu Fei Zhenbi Lanzhou Desert Research Institute Chinese Academy of Sciences Lanzhou Gansu China

At least at the beginning of the last glacial epoch, the facies belts of dune sand, sandy loam and loess formed by winds had existed in the Taklimakan desert and areas south of it. There were no appreciable changes in the NE and NW wind systems and their wind fqrces that deposited dune sand, sandy loam and loess in the global cold stage since the last glacial epoch (accordingly no marked shifts of the boundaries of these aeolian facies belts took place. In the global warm stage since then, the climate in the Taklimakan desert and areas south of it became warm and dry, resulting in ablation of substantial volumes of ice and snow in their surrounding mountains and thus forming alluvial and diluvial deposits in the region. The alluvial-diluvial actions, however, failed to change the general framework of aeolian facies belts.

关键词： Taklimakan desert sandy loam belt loess belt last glacial depositional environment

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Variability of snail growing season at the Chinese Loess Plateau during the last 75 ka

Variability of snail growing season at the Chinese Loess Pla...

引用

中国科学院地质与地球物理研究所2012年度（第12届）...

作者： HUANG LinPei WU NaiQin GU ZhaoYan CHEN XiaoYun Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of Sciences Graduate University of Chinese Academy of Sciences

Knowledge of seasonal climate change is one of the key issues facing Quaternary paleoclimatic studies and estimating seasonal climate change is difficult,especially changes such as seasonal length on glacial-mterglacial timescales.The stable isotope composition from seasonal land snail shells provides the potential to reveal seasonal climatic features.Two modern land snail species, cold-aridiphilous Pupilla aeoli and thermo-humidiphilous Punctum orphana,were collected from different climatic zones in 18 localities across the Chinese Loess Plateau,spanning 11 degrees of longitude and covering a range of 1000 km.The duration of the snail growing season(temperature≥10℃) was shorter(202±6 d) in the eastern Loess Plateau compared with in the western Loess Plateau(162±7 d).TheδC of P.aeoli shells was -9.1‰to -4.7‰and -5.0‰to 0.3‰forδO.For P.orphana,theδC ranged from -9.1‰to -1.9‰and -8.9‰to -2.9‰forδO.Both theδC andδO differences between the two snail species were reduced from the east to the western Loess Plateau(2.8‰to 0.2±l.l‰forδC and 4.7‰to 2.9±1.3‰forδO).These isotopic differences roughly reflect the difference in the growing season lengths between the east and west Loess Plateau indicating that the duration of the snail growing season shortens by 15 d or 19 d if the difference decreases by l‰inδC or S O,respectively. Thus,the difference inδC andδC between both snail species can be used to reveal the length of the snail growing season in the past.Based on our investigation,the length of the snail growing seasons from the Xifeng region during the last 75 ka was reconstructed.During the mid-Holocene(8-3 ka),the mean isotopic difference from both snail species reached maximum values of 2.6±0.7‰and 2.1±1 A‰forδC andδC,respectively.This was followed by MIS 3 that ranged from 2.5±0.4‰forδC and 1.6±0.8‰forδC.The last glacial Maximum changed by only 0.2‰and 0.4‰forδC andδC,respectively. Therefore,we estimate that the duration of the snail growing seasons to be～200±10 d during the mid-Holocene,190±6 d in MIS 3 and 160±3 d

关键词： land snail stable carbon and oxygen isotopes last glacial snail growing season Xifeng loess sequence

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：