| 青藏高原中部色林错湖泊沉积物色度反映末次冰盛期以来区域古气候演化 |
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| 引用本文： | 杜丁丁,Muhammad Saleem Mughal,Dembele Blaise,张成君.青藏高原中部色林错湖泊沉积物色度反映末次冰盛期以来区域古气候演化[J].干旱区地理,2019,42(3):551-558. |
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| 作者姓名： | 杜丁丁 Muhammad Saleem Mughal Dembele Blaise 张成君 |
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| 作者单位： | 东华理工大学地球科学学院,江西南昌,330013;兰州大学地质科学与矿产资源学院;甘肃省西部矿产资源重点实验室,甘肃兰州730000 |
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| 基金项目： | 国家自然科学基金项目(41173015, 41571177)；中央高校基本科研业务费专项资金资助(862457, lzujbky-2017-it26) |
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| 摘 要： | 色林错湖位于青藏高原内部，是西藏第一大咸水内陆湖。研究区剖面选自色林错第三湖泊阶地，利用常用气候替代指标色度，结合粒度、碳酸盐含量［CaCO3（%）］、矿物分析和全有机质（TOC）等进行对比分析，同时采用14C测年方法对剖面进行准确的年代划分，初步探讨了末次冰盛期以来色林错湖泊沉积物色度增强机制的差异性。研究表明： a*、b*与中粗粒砂、磁化率具有较好的相关性；亮度L*与CaCO3（%）具较好相关性；因而沉积物色度变化可反应区域古气候变化。同时对湖泊沉积物矿物分析发现，影响色度变化的制色矿物主要是针铁矿，且以还原环境为主。红度a*高值与亮度L*低值对应气候暖湿气候环境，沉积物粒度较粗，碳酸盐含量低，有机质含量高，磁化率较高值；反之，红度a*低值，L*高值，粒度较细，碳酸盐含量高，有机质含量低，磁化率低值，对应干冷气候。在17.4～15.5 cal ka BP阶段，对应干冷的气候特点；在15.5～10.4 cal ka BP阶段，对应温暖湿润的气候；在10.4～5.2 cal ka BP阶段，整体属于温暖湿润的气候特点；其中，在9.7～9.4 cal ka BP和8.75～8.5 cal ka BP为两个重要的冷事件，属于干湿的气候特点；在5.2～1.2 cal ka BP阶段，反映了干冷的气候特征；在4.3～4.0 cal ka BP，3.3～3.0 cal ka BP和2.4～1.75 cal ka BP，反映了干旱温暖的气候特点；在1.2 cal ka BP以后，色林错湖湖水迅速下降。
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| 关 键 词： | 色度 粒度 古气候环境 色林错湖泊 |
| 收稿时间： | 2018-10-19 |
Paleoclimatic changes reflected by diffuse reflectance spectroscopy since LastGlacial Maximum from Selin Co Lake sediments,central Qinghai-Tibetan Plateau |
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| DU Dingding,Muhammad Saleem Mughal,Dembele Blaise,ZHANG Chengjun.Paleoclimatic changes reflected by diffuse reflectance spectroscopy since LastGlacial Maximum from Selin Co Lake sediments,central Qinghai-Tibetan Plateau[J].Arid Land Geography,2019,42(3):551-558. |
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| Authors: | DU Dingding Muhammad Saleem Mughal Dembele Blaise ZHANG Chengjun |
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| Abstract: | The Selin Co Lake is located in the central QinghaiTibetan Plateau,China,which is a sensitive region to climate. Meanwhile,the area is less influenced by human activities.In recent years,the region became a hotspot for the paleoenvironmental research community.In this paper,the profile is selected in the third terrace of the lakeshore and 122 samples were collected there.By using 14C dating method,we get the exact age of the profile.The combination of many different methods,such as TOC,X ray diffraction (XRD),CaCO3 (%),magnetic susceptibility and grain size,were used to investigate the paleoenvironment.Three components were considered in this investigation including red (a*),yellow (b*) and brightness (L*).The a* and b* are mainly related to the value of goethite and the a* in sediment is primarily related to wetwarm climate,which can be used to monitor paleoclimatic changes in the area.The L* has a good correlation with TOC and CaCO3(%); and almost has correlation with magnetic susceptibility and grain size.If the grain size of the lake sediment became coarser,magnetic susceptibility was bigger,the organic content went higher,and the CaCO3(%) got decreased,all these indicated the climate was in the warmwet condition which was reflected by a higher a* value and a lower L* value; otherwise,the climate was in the colddry condition which was reflected by a lower a* value and a higher L* value.Therefore,the paleoclimatic changes were divided into 5 stages: The colddry climatic period from 13.33 to 12.23 ka BP,the significant colddry climatic period from 12.23 to 10.07 ka BP when the Younger Dryas event occurred,the Holocene Megathermal period from 10.68 to 8.70 ka BP when the values of a* and b* kept higher and the value of L* sustained a dropping trend, the warmwet climatic period from 8.70 to 3.93 ka BP and the colddry climatic period from 3.93 to 0 ka BP. The result was very similar to the monsoon changes in Qinghai Tibetan Plateau. |
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| Keywords: | Hue grain size paleoclimate and paleo environment Selin Co Lake |
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