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1.
萨拉乌苏河流域米浪沟湾末次冰期早冰阶时期记录了5.5个由古沙丘砂与河流相、湖沼相构成的沉积旋回。对各沉积旋回的粒度及微量元素分析表明,河流相和湖沼相的平均粒径Mz、分选系数σ和SC/D的值明显高于古沙丘砂,河湖相中的微量元素Mn、P、Rb、Zr、V、Ni含量普遍较古沙丘砂含量高,而Ba、Co等则呈现相反的变化;这些气候代用指标的波动构成了与沉积旋回相对应的5.5个粒度及微量元素变化旋回,指示了该地末次冰期早冰阶至少经历了6次冷干和5次暖湿的气候波动,其中若干次气候回暖事件和冷干事件可与格陵兰冰芯和葫芦洞石笋等记录的D/O事件和Heinrich事件相对应。米浪沟湾剖面地层记录的千年尺度气候波动既是对东亚季风环流演变历史的体现,同时也是对全球气候变化的响应。  相似文献   

2.
 毛乌素沙漠东南缘萨拉乌苏河流域米浪沟湾剖面MGS1层段含有11个由古沙丘砂与河湖相或古土壤构成的沉积旋回。通过对该层段粒度和CaCO3的分析,发现其河湖沼相和古土壤的平均粒径、分选系数、偏度和峰态的值明显高于古沙丘砂;CaCO3含量在古沙丘砂及其上覆的河湖相和古土壤中依次变化于0.07%~0.32%（平均值为0.16%）、0.05%~1.50%（0.27%）和0.06%~1.42%（0.64%）,并与平均粒径呈显著相关（相关系数0.8）;构成与沉积旋回波动韵律相同的11个峰谷交替的粒度和CaCO3旋回,指示了全新世气候冷、暖的变化过程和东亚冬夏季风千年尺度交替变化的气候旋回。这些旋回中的冬季风主导时期可与北大西洋8 200、5 000、4 000、2 700、1 400 a BP等寒冷事件进行对比,和中国若干地点的气候波动具有良好对应关系,可能表明全新世东亚季风在全球大气、海洋、陆地和全球冰量变化的共同作用下,表现为干冷冬季风和暖湿夏季风的相互交替的千年尺度的气候变化特征。  相似文献   

3.
测定、分析毛乌素沙漠东南缘萨拉乌苏河流域米浪沟湾剖面MGS2层段的粒度与CaCO3,发现该层段不同沉积相粒度Mz和σ呈现峰谷变化,CaCO3含量在沙丘砂及其上覆的河流相和湖沼相中依次变化于0-2.94%(平均值0.39%)、0.14%-2.68%(1.43%)和0.39%-15.57%(8.82%),并与Mz呈显著相关,构成与沉积旋回波动韵律相同的5.5个峰谷交替的粒度与CaCO3旋回。研究表明,毛乌素沙漠冬季风盛行时期沙丘砂强烈堆积,CaCO3发生迁移;夏季风盛行时期河流相和湖沼相发育,粉砂和粘土含量增加,CaCO3相对聚集。这些旋回代表东亚冬夏季风千年尺度交替变化的气候旋回。  相似文献   

4.
萨拉乌苏河流域末次间冰期 古土壤化学风化与古气候   总被引：7，自引：0，他引：7  
内蒙萨拉乌苏河流域米浪沟湾剖面末次间冰期发育5 层古土壤。对这5 层古土壤的形 态特征、粒度、扫描电镜及化学风化等分析结果表明: (1) 这些古土壤具有与华北现代褐土相 似的形态特征; (2) 粘化率中部高和石英颗粒表面硅质溶蚀-沉淀现象表明古土壤层中发生过 风化成壤作用; (3) 用K2O/Na2O、Al2O3/Na2O、MnO/Al2O3、CIA 及A-CN-K 图解与华北现代 褐土作对比分析, 发现它们的化学风化特征极为相似; (4) 用气温及降水量与CIA 值的回归 关系方程, 得出5 层古土壤发育时期的水热状况确与华北现代的暖温带半湿润季风性气候大 致相同或更显暖湿。形态特征、粒度、石英颗粒表面特征和化学风化特征等多个方面具备了 与现代华北褐土类似的化学风化成壤特征, 证明这些古土壤是在与华北相似的暖温带半湿润 季风性气候条件下形成的。  相似文献   

5.
 位于鄂尔多斯高原萨拉乌苏河米浪沟湾剖面是重建毛乌素沙地晚更新世以来古气候的理想地点。其末次间冰阶(MIS3)层序含4种沉积相,划分为19个沉积单元,构成9.5个风成的砂丘砂与河流相、湖相和古土壤交替的沉积旋回。主元素分析结果显示,该剖面MIS3层序中河流相、湖相和古土壤的Al2O3、TOFE、CaO、MgO、K2O、Na2O、TiO2含量明显高于古风成砂, 而SiO2则相反, 构成与沉积旋回相应的9.5个元素波动旋回。这些元素旋回指示了该地末次间冰阶至少经历了10次温湿(W事件)和9次冷干(C事件)气候波动,且可划分为MIS3e(58.90~49.50 ka BP)、MIS3d(49.50~40.70 ka BP)、MIS3c(40.70~36.90 ka BP)、MIS3b(36.90~27.00 ka BP)和MIS3a(27.00~22.30 ka BP)等5个亚段。其中, 19次冷/暖波动可与格陵兰GRIP冰芯δ18O冰段/间冰段大致对应, 5个亚段与我国古里雅冰芯和V23-81冷性浮游有孔虫数代表的北大西洋地区气候也具有较好的可比性。  相似文献   

6.
萨拉乌苏河流域150 ka BP以来的粒度旋回   总被引：18，自引：1，他引：18  
萨拉乌苏河流域米浪沟湾地层剖面150kaBP以来古流动砂丘砂与河湖相和古土壤在粒度上具有多次显著的粗细韵律交替变化，粒度参数-Mz、σ、Sk、Kg和SC/D亦随之响应为多波动峰谷交替的态势，同时，粒度特征值-φ5、φ16φ、φ25、φ50、φ84、φ9相应地表现为非常有节奏地跳动，据此，将米浪沟湾剖面划分为27个粒度粗细沉积旋回，并认为其是150kaBP以来在东亚冬夏古代季风交替影响下沙漠演变的一个颇为完整的气候-地质过程记录。  相似文献   

7.
萨拉乌苏河流域与MIS2相同时代的MGS2地层段记录了5.5个由风成砂与河流相或湖沼相构成的沉积旋回,通过对各沉积旋回的主要氧化物分析表明：河湖相中Al2O3、TOFE、K2O、MgO、CaO、Na2O、TiO含量通常明显高于风成砂,而SiO2含量则呈现相反的变化,构成了与沉积旋回相对应的5.5个主要氧化物变化旋回。结合各主要氧化物的化学迁移特性和剖面所在区域的地貌特征进行分析,认为该剖面的主要氧化物变化旋回是气候波动的反映,一个主要氧化物含量变动旋回指示了一个干冷-暖湿旋回,也即一个冬夏季风先后演替的气候旋回。MGS2持续的时间仅为12 ka,一个冬夏季风环境的变化大致平均仅需要2 ka,一个冬季风或者夏季风环境的平均持续时间大约1 ka。显然,这是一个千年尺度的环境变化。研究还表明,MGS2气候波动与晚冰期气候变化以及相关的Heinrich事件具有良好的对应关系。可以推断,MGS2记录的千年尺度环境变化是全球环境变化在本区域的反映。  相似文献   

8.
萨拉乌苏地区位于毛乌素沙漠东南部,属于东亚季风的北部边缘区。由于萨拉乌苏地区还拥有我国非常重要的旧石器考古遗址,该地区的气候变化广受国内外学者的关注。通过野外考察发现,在萨拉乌苏河谷酒坊台地区的上部地层中,广泛沉积有两层湖相沉积物。在米浪沟湾选择剖面,共采集了8个光释光样品,以此来恢复湖泊发育的年代及环境变化。根据地层沉积相对比和年代学结果,得出在约40~30 ka毛乌素沙漠东南边缘地区发育有古湖泊,说明当时的有效湿度较高。通过区域对比,发现毛乌素沙漠和其他亚洲季风区在氧同位素3阶段(MIS3)晚期都有古湖形成或高湖面记录,说明这些湖泊的演化过程存在一定的等时性,反映当时亚洲夏季风的增强及有效湿度的增加。  相似文献   

9.
The Salawusu Formation of Milanggouwan section in Salawusu River Valley includes 7 layers of paleo-mobile dune sands, and 4 layers of paleo-fixed and semi-fixed dune sands. Their structures have been observed and their grain size, surface textural features and several main chemical elements have been analyzed. The results showed that： 1） Some of the aeolian structural characteristics of these dune sands are similar to that of the recent dune sands. 2） They are also similar to the recent dune sands in grain size components, and parameters of Mz,σ, Sk and Kg, as well as in several main chemical components. 3） The scattergrams of Mz-σ and SiO2-Al2O3＋TOFE and the probability curves of grain size showed that these paleo-dune sands are different from paleosols and fluvio-lacustrine facies, but are consistency with recent dune sands. 4） Quartz sands have well roundness and surface textural features such as dish-shaped pits, crescent-shaped pits, pockmarked pits, upturned cleavage plates, siliceous precipitates and siliceous crevasses, indicating that they had been carried for a long time by the wind. As the 11 layers of paleo-dune sands possess the aeolian characteristics in structure, grain size, surface textural features and chemical elements, the origin of their formation should be attributed to eolation.  相似文献   

10.
萨拉乌苏河地区晚更新世环境演化   总被引：10，自引：0，他引：10  
对萨拉乌苏河地区上更新统地层作进一步划分的基础上,本文论述本区晚更新世前期萨拉乌苏组沉积时的古地理环境为暖湿的森林草原.后期城川组主要形成于干冷的荒漠草原-荒漠环境,期间经历了一系列温凉湿润的灌丛草原-疏林草原、森林草原等环境的交替演化过程.  相似文献   

11.
The Salawusu Formation of Milanggouwan section in Salawusu River Valley in-cludes 7 layers of paleo-mobile dune sands, and 4 layers of paleo-fixed and semi-fixed dune sands. Their structures have been observed and their grain size, surface textural features and several main chemical elements have been analyzed. The results showed that: 1) Some of the aeolian structural characteristics of these dune sands are similar to that of the recent dune sands. 2) They are also similar to the recent dune sands in grain size components, and parameters of Mz, σ, Sk and Kg, as well as in several main chemical components. 3) The scattergrams of Mz-σ and SiO2–Al2O3+TOFE and the probability curves of grain size showed that these paleo-dune sands are different from paleosols and fluvio-lacustrine facies, but are consistency with recent dune sands. 4) Quartz sands have well roundness and surface textural features such as dish-shaped pits, crescent-shaped pits, pockmarked pits, upturned cleavage plates, siliceous precipitates and siliceous crevasses, indicating that they had been carried for a long time by the wind. As the 11 layers of paleo-dune sands possess the aeolian characteristics in structure, grain size, surface textural features and chemical elements, the origin of their formation should be attributed to eolation.  相似文献   

12.
The palaeo-mobile dune sands and fluvio-lacustrine facies with palaeosols in Milanggouwan stratigraphic section of the Salawusu River valley situated at the southeast of the Mu Us Desert experienced abundant remarkable alternative changes of coarse and fine rhythms in grainsize since 150 ka BP, and the grain-size parameters — Mz,σ, Sk, Kg and SC/D also respond to the situation of multi-fluctuational alternations between peak and valley values. Simultaneity the grainsize eigenvalues — Φ5, F16, Φ25, Φ50, Φ75, Φ84 and Φ95 are respondingly manifested as greatly cadent jumpiness. Hereby, the Milanggouwan section can be divided into 27 grain-size coarse and fine sedimentary cycles, which can be regarded as a real and integreted record of climate-geological process of desert vicissitude resulted from the alternative evolvement of the ancient winter and summer monsoons of East Asia since 150 ka BP.  相似文献   

13.
The components of the primary elements in the dune sands for the MGS1 subsec-tion of the Milanggouwan section in the Salawusu River valley, compared with those of mod-ern dune sands, show that they were caused by East Asian winter monsoon in the Mu Us desert during Holocene. The examined ages for the 11 layers of dune sands, based on the average sedimentary rate, are: 0 to 960, 1350–2240, 2470 to 3530, 4000 to 4180, 4290 to 4350, 4380 to 4760, 5040 to 5920, 6570 to 8270, 9020 to 9700, 9880 to 10160 and 10580 to 11080 a BP, respectively. The climatic events indicated by these dune sands are consistent with those records in the Huguangyan volcanic lake, Zoige peat bog, Hulu cave and Dunde ice core, particularly with the climatic fluctuations of the North Atlantic since 11 000 a BP. Among them, patterns from B0 to B8 correspond to the peak values of 0MD, 2D, 4D, 6D+8D+10D, 12D, 14D, 16D, 18D and 20D respectively. It might be caused by the North Atlantic ice age induced by the heat circulation, which strengthened the polar high pressure and Siberian-Mongolian high pressure and further led to the dominance of the winter mon-soon over China’s desert area.  相似文献   

14.
Grain-size cycles in Salawusu River valley since 150 ka BP   总被引：1，自引：2，他引：1  
Situated at the southeast Mu Us Desert on the Ordos Plateau of China, the Salawusu River valley, contains abundant environmental vicissitude information of the East Asia Monsoon since Late Quaternary and serves as an excellent site for researches of sedimentology and climatology etc. As early as 1924, the French paleontologists Teilhard de Chardin et al. found the Upper-Pleistocene Salawusu Formation and drew an outline of the 搃deal section through the loessic lands of N and the SE co…  相似文献   

15.
The components of the primary elements in the dune sands for the MGS1 subsection of the Milanggouwan section in the Salawusu River valley, compared with those of modern dune sands, show that they were caused by East Asian winter monsoon in the Mu Us desert during Holocene. The examined ages for the 11 layers of dune sands, based on the average sedimentary rate, are： 0 to 960, 1350-2240, 2470 to 3530, 4000 to 4180, 4290 to 4350, 4380 to 4760, 5040 to 5920, 6570 to 8270, 9020 to 9700, 9880 to 10160 and 10580 to 11080 a BP, respectively. The climatic events indicated by these dune sands are consistent with those records in the Huguangyan volcanic lake, Zoige peat bog, Hulu cave and Dunde ice core, particularly with the climatic fluctuations of the North Atlantic since 11 000 a BP. Among them, patterns from B0 to B8 correspond to the peak values of 0MD, 2D, 4D, 6D＋8D＋10D, 12D, 14D, 16D, 18D and 20D respectively. It might be caused by the North Atlantic ice age induced by the heat circulation, which strengthened the polar high pressure and Siberian-Mongolian high pressure and further led to the dominance of the winter monsoon over China＇s desert area.  相似文献   

16.
分析滴哨沟湾剖面全新统DGS1段的粒度数据,认为流动沙丘砂、泥炭、砂质古土壤、古固定-半固定沙丘砂到湖沼相和次生黄土的颗粒总体上变细,分选变差。结合腹足类动物化石和湖沼相地层中石英砂粒表面电镜扫描,认为DGS1粒度结果实际上是全新世以来多次冬夏季风的交互演替过程的气候-地质记录。据此,将DGS1粒度信号记录的全新世气候分为4个阶段——全新世早期好转期、全新世鼎盛期、大暖期向寒冷期转变波动期和降温不稳定的沙漠化频繁变化时期。  相似文献   

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