Climate variability and its magnetic response recorded in a lacustrine sequence in Heqing basin at the SE Tibetan Plateau since 900 ka
Climate variability and its magnetic response recorded in a lacustrine sequence in Heqing basin at the SE Tibetan Plateau since 900 ka
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青藏高原东南部鹤庆盆地900ka以来湖泊序列记录的气候变化及其磁响应
DOI：
10.1093/gji/ggv033
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发表时间：
2015-04
影响因子：
2.8
通讯作者：
Zhu, Xiuhua
中科院分区：
文献类型：
--
作者：
Gleixner, Gerd;Wang, Sumin;Yang, Xiangdong;Zhu, Xiuhua
鹤庆盆地的湖相沉积为青藏高原东南部季风区长期高分辨率的古气候研究提供了良好的档案。在这项研究中，我们调查的气候意义的磁参数分析过去的气候变化。为此，我们进行了全面的时间序列和统计分析，以前公布的代理数据从168米长的钻芯（Core-HQ），跨越10900 -30 ka，主要包括磁性参数和碳酸盐含量（CC）。此外，我们还研究了主要形成于石灰岩基岩上的集水区现代土壤的磁性。主要调查结果如下：（1）现代土壤和沉积物中均含有磁铁矿（Mt）、磁赤铁矿（Mgh）和赤铁矿（Ht）的混合物，但土壤的磁浓度高一个数量级：（2）土壤中以Mt/Mgh的超顺磁性（SP）组分为主，而在Core-HQ中SP组分的贡献一般很低;（3）土壤中还存在较大的Mt/Mgh和Ht粒级。我们解释的变化的磁浓度和CC在核心HQ的增加风运输的土壤和减少地表水运输的碳酸盐和土壤在不太潮湿的时期。集水区磁铁矿的低温氧化是反映风化条件的另一个关键过程，可能对湿度敏感; LTO的程度可以通过磁性参数ARM/SIRM和S-比率进行半量化。结合CC、ARM/SIRM和S比值，我们得到了风化强度（WI）。沿着Core-HQ的WI指数变化表明，在100-kyr偏心率尺度上，在下部，特别是在630-380 ka，其次是一个长期（320-80 ka）的持续较弱的风化（干燥？）低变化的条件下，和更强的风化（潮湿？）80 ka的条件下。我们认为，印度夏季风的影响减少占该地区的水分供应和较低的气候变率。
The lacustrine deposits in Heqing basin provide an excellent archive for long-term high-resolution palaeoclimate studies in the monsoon-dominated southeastern Tibetan Plateau region. In this study, we investigate the climatic significance of magnetic parameters for analysing the variability of the past climate. For this, we performed comprehensive time-series and statistical analysis on previously published proxy data from a 168-m-long drill core (Core-HQ) that spans ∼900–30 ka, comprising mainly magnetic parameters and carbonate content (CC). Moreover, we investigated magnetic properties of modern soil in the catchment that predominantly formed on limestone bedrock. Key findings are: (1) modern soils and sediments of Core-HQ both contain a mixture of magnetite (Mt), maghemite (Mgh) and hematite (Ht), but magnetic concentration of the soils is one order higher; (2) a superparamagnetic (SP) fraction of Mt/Mgh dominates in the soils whereas in Core-HQ the SP contribution is generally very low; (3) a larger grain-size fraction of Mt/Mgh and Ht is also present in the soils. We explain variations of magnetic concentration and CC in Core-HQ by an increased wind transport of soil and a decreased surface water transport of carbonate and soil in less humid periods. Low-temperature oxidation of magnetite in the catchment is as another crucial process that reflects weathering conditions and is likely sensitive to humidity; the degree of LTO can be semi-quantified by the magnetic parameters ARM/SIRM andS-ratio. Combining CC, ARM/SIRM andS-ratio values, we derive a weathering intensity (WI). The WI index variation along Core-HQ shows strong fluctuations on a 100-kyr eccentricity scale in the lower part, especially during ∼630–380 ka, followed by a long period (∼320–80 ka) of persistently weaker weathering (drier?) conditions with low variability, and a rapid return of much stronger weathering (wetter?) conditions at ∼80 ka. We suggest that a reduced influence of the Indian summer monsoon accounts for less moisture supply to the region and lower climatic variability.
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DOI：
10.1016/j.palaeo.2010.12.007
发表时间：
2011-02
期刊：
Palaeogeography, Palaeoclimatology, Palaeoecology
影响因子：
--
作者：
Tatsuya Hayashi
通讯作者：
Tatsuya Hayashi
结合磁性地层学、放射性碳测年和碳酸盐循环性的年龄微调：鹤庆盆地（中国云南）覆盖过去 1 Myr 的湖泊沉积物示例
影响因子：
3
作者：
Shouyun Hu
通讯作者：
Shouyun Hu
影响因子：
3
作者：
R. Fujii;H. Sakai
通讯作者：
R. Fujii;H. Sakai
DOI：
10.3402/tellusb.v64i0.18703
发表时间：
2012-01
期刊：
Tellus B: Chemical and Physical Meteorology
影响因子：
--
作者：
W. An;Xiaohong Liu;S. Leavitt;Jiawen Ren;Weizheng Sun;Wenzhi Wang;Yu Wang;Guobao Xu;Tuo Chen-Tu
通讯作者：
W. An;Xiaohong Liu;S. Leavitt;Jiawen Ren;Weizheng Sun;Wenzhi Wang;Yu Wang;Guobao Xu;Tuo Chen-Tu
影响因子：
5
作者：
A. White;A. Blum;T. Bullen;D. Vivit;M. Schulz;J. Fitzpatrick
通讯作者：
A. White;A. Blum;T. Bullen;D. Vivit;M. Schulz;J. Fitzpatrick