腾格里沙漠南缘地处中国西北沙漠与黄土交错带,也是东亚冬季风与夏季风交替控制的过渡地带,其对全球气候变化十分敏感,是研究古气候与古生态的理想地点。选择该区域一典型剖面即＂土门剖面＂（TMS）为代表,通过野外考察、采样和室内采...腾格里沙漠南缘地处中国西北沙漠与黄土交错带,也是东亚冬季风与夏季风交替控制的过渡地带,其对全球气候变化十分敏感,是研究古气候与古生态的理想地点。选择该区域一典型剖面即＂土门剖面＂（TMS）为代表,通过野外考察、采样和室内采用X-射线荧光光谱仪进行主量元素测试,探讨了以该剖面主元素氧化物为气候代用指标指示的腾格里沙漠沙漠南缘末次间冰期5e（MIS5e）的古气候变化。年代相当于MIS5e的土门剖面末次间冰期5e层段（TMS5e）由16层风成砂、11层湖积黄土和5层湖相构成,记录了14.5个风成砂与湖相或和湖积黄土构成的沉积旋回与元素旋回。分析结果显示,该层段8种主量元素的含量高低依次为：SiO2〉Al2O3〉CaO〉TOFE（Fe O＋Fe2O3）〉K2O〉MgO〉Na2O〉TiO2,平均值依次为64.11%、11.31%、5.15%、4.08%、2.37%、2.26%、2.01%、0.41%。这些主量元素在TMS5e层段的垂直方向上呈两组镜像对称变化：一组为SiO2,其含量在风成砂层位显峰态,而在湖相和湖积黄土层位显谷态;另一组为Al2O3、TOFE、CaO、Mg O、Na2O、K2O、TiO2,它们在风成砂层位呈谷态,在湖相和湖积黄土层位显谷态。土门剖面TMS5e层段的主元素氧化物指示的MIS5e腾格里沙漠南缘的气候是不稳定的,经历了14.5次暖湿与冷干交替的气候波动,且可划分为TMS5e5（139~129.30 ka BP）、TMS5e4（129.30~124 ka BP）、TMS5e3（124~119.50 ka BP）、TMS5e2（119.5~116.5 ka BP）和TMS5e1（116.5~113.70 ka BP）等5个亚段,其在时代上与末次间冰期5e GRIP冰芯δ18O记录的5个阶段具有遥相关关系。该研究深化了对我国西北季风边缘区MIS5e古气候状况的了解,也为国际上仍有争议的＂MIS5e气候是不稳定＂的理论观点提供了有力的地质证据。展开更多
The TMS5e sequence from the Tumen section, at the southern edge of Tengger Desert in the northwestern China, is synchronous with Marine Isotope Stage 5e （MIS5e）. It consists of 16 layers of aeolian dune sands, 11 la...The TMS5e sequence from the Tumen section, at the southern edge of Tengger Desert in the northwestern China, is synchronous with Marine Isotope Stage 5e （MIS5e）. It consists of 16 layers of aeolian dune sands, 11 layers of lacustrine loess-like facies, and 5 layers of lacustrine facies. The results of grain-size analysis shows that the pa- laeo-mobile dune sands, palaeo-fixed to semi-fixed dune sands and loess-like sandy loams are mainly composed of sands, ranging from 70% to 96%; their silt contents ranged from 4% to 20%, and their clay contents ranged from 1% to 5%; the climate under which the aeolian dune sands were deposited is similar to that under which modern mobile dune sands form, which is caused by the dominance of the cold, dry East Asian winter monsoon. In contrast, the lacustrine loess-like facies and lacustrine facies had a lower sand contents than those of the three aeolian dune sands, but have higher silt and clay contents, most of their sand content ranged from 30% to 60%, their silt contents ranged from 35% to 55%, and their clay contents ranged from 6% to 20%. The lacustrine loess-like facies and lacustrine facies formed under the influence of the warm, humid East Asian summer monsoon based on their similarity with modern sediments. The grain-size indicator Mz （mean grain diameter） and the SC/D value in the TMS5e sequence indicate climatic insta- bility at the southern edge of the Tengger Desert during MIS5e, with at least 14 fluctuations between a warm, humid climate and a cold, dry climate, divided into five stages： TMS5e5 （139 kyr to 129.3 kyr B.P.）, TMS5e4 （129.3 kyr to 124 kyr B.P.）, TMS5e3 （124 kyr to 119.5 kyr B.P.）, TMS5e2 （119.5 kyr to 116.5 kyr B.P.）, and TMS5el （116.5 kyr to 113.7 kyr B.P.）. These correspond roughly to MIS5e5, MIS5e4, MIS5e3, MIS5e2, and MIS5el, respectively, in the GRIP ice core data.展开更多
文摘腾格里沙漠南缘地处中国西北沙漠与黄土交错带,也是东亚冬季风与夏季风交替控制的过渡地带,其对全球气候变化十分敏感,是研究古气候与古生态的理想地点。选择该区域一典型剖面即＂土门剖面＂（TMS）为代表,通过野外考察、采样和室内采用X-射线荧光光谱仪进行主量元素测试,探讨了以该剖面主元素氧化物为气候代用指标指示的腾格里沙漠沙漠南缘末次间冰期5e（MIS5e）的古气候变化。年代相当于MIS5e的土门剖面末次间冰期5e层段（TMS5e）由16层风成砂、11层湖积黄土和5层湖相构成,记录了14.5个风成砂与湖相或和湖积黄土构成的沉积旋回与元素旋回。分析结果显示,该层段8种主量元素的含量高低依次为：SiO2〉Al2O3〉CaO〉TOFE（Fe O＋Fe2O3）〉K2O〉MgO〉Na2O〉TiO2,平均值依次为64.11%、11.31%、5.15%、4.08%、2.37%、2.26%、2.01%、0.41%。这些主量元素在TMS5e层段的垂直方向上呈两组镜像对称变化：一组为SiO2,其含量在风成砂层位显峰态,而在湖相和湖积黄土层位显谷态;另一组为Al2O3、TOFE、CaO、Mg O、Na2O、K2O、TiO2,它们在风成砂层位呈谷态,在湖相和湖积黄土层位显谷态。土门剖面TMS5e层段的主元素氧化物指示的MIS5e腾格里沙漠南缘的气候是不稳定的,经历了14.5次暖湿与冷干交替的气候波动,且可划分为TMS5e5（139~129.30 ka BP）、TMS5e4（129.30~124 ka BP）、TMS5e3（124~119.50 ka BP）、TMS5e2（119.5~116.5 ka BP）和TMS5e1（116.5~113.70 ka BP）等5个亚段,其在时代上与末次间冰期5e GRIP冰芯δ18O记录的5个阶段具有遥相关关系。该研究深化了对我国西北季风边缘区MIS5e古气候状况的了解,也为国际上仍有争议的＂MIS5e气候是不稳定＂的理论观点提供了有力的地质证据。
基金Foundation item:Under the auspices of State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,Chinese Academy of Sciences (No.SKLLQG0901,SKLLQG1013)Research Fund for the Doctoral Program of Higher Education of China (No.20094407120004)
文摘The TMS5e sequence from the Tumen section, at the southern edge of Tengger Desert in the northwestern China, is synchronous with Marine Isotope Stage 5e （MIS5e）. It consists of 16 layers of aeolian dune sands, 11 layers of lacustrine loess-like facies, and 5 layers of lacustrine facies. The results of grain-size analysis shows that the pa- laeo-mobile dune sands, palaeo-fixed to semi-fixed dune sands and loess-like sandy loams are mainly composed of sands, ranging from 70% to 96%; their silt contents ranged from 4% to 20%, and their clay contents ranged from 1% to 5%; the climate under which the aeolian dune sands were deposited is similar to that under which modern mobile dune sands form, which is caused by the dominance of the cold, dry East Asian winter monsoon. In contrast, the lacustrine loess-like facies and lacustrine facies had a lower sand contents than those of the three aeolian dune sands, but have higher silt and clay contents, most of their sand content ranged from 30% to 60%, their silt contents ranged from 35% to 55%, and their clay contents ranged from 6% to 20%. The lacustrine loess-like facies and lacustrine facies formed under the influence of the warm, humid East Asian summer monsoon based on their similarity with modern sediments. The grain-size indicator Mz （mean grain diameter） and the SC/D value in the TMS5e sequence indicate climatic insta- bility at the southern edge of the Tengger Desert during MIS5e, with at least 14 fluctuations between a warm, humid climate and a cold, dry climate, divided into five stages： TMS5e5 （139 kyr to 129.3 kyr B.P.）, TMS5e4 （129.3 kyr to 124 kyr B.P.）, TMS5e3 （124 kyr to 119.5 kyr B.P.）, TMS5e2 （119.5 kyr to 116.5 kyr B.P.）, and TMS5el （116.5 kyr to 113.7 kyr B.P.）. These correspond roughly to MIS5e5, MIS5e4, MIS5e3, MIS5e2, and MIS5el, respectively, in the GRIP ice core data.
