机构地区:[1]广州地理研究所/广东省地理空间信息技术与应用公共实验室,广东广州510070 [2]华南师范大学地理科学学院,广东广州510631 [3]中国科学院地球环境研究所黄土与第四纪地质国家重点实验室,陕西西安710061 [4]地质出版社,北京100083 [5]广西师范学院地理科学与规划学院,广西南宁530001
出 处:《地理科学》2016年第6期926-934,共9页Scientia Geographica Sinica
基 金:国家自然科学基金重大项目(41290250);国家自然科学基金(41471159)资助~~
摘 要:对巴丹吉林沙漠东南缘查格勒布鲁剖面该层段的CGS3a层段(Chagelebulu Section 3a)139个样品的主元素——Si O2、Al2O3、TOFE(Fe2O3+Fe O)进行分析,划分出与地层旋回对应的5.5个化学元素旋回。研究认为:沙丘砂和黄土中Si O2呈现的峰和Al2O3、TOFE、(TOFE+Al2O3)/Si O2和CIA呈现的谷是类似于现代干冷的冬季风在过去多次作用的结果,而嗣后的湖相Si O2呈现的谷和Al2O3、TOFE、(TOFE+Al2O3)/Si O2和CIA的呈现的峰是类似于现代暖湿的夏季风在过去多次作用的结果。即35 000~25 000 a B.P.该沙漠经历了5次冬季风和6次夏季风交替的气候波动,这些气候事件与GRIP冰芯氧同位素记录的D/O(Dansgaard/Oeschger)事件相对应,Heinrich事件也在其中有很好体现。CGS3a层段所记录的千年尺度的气候波动可能是受到了北大西洋气候突变的影响。The CGS3 a segment of the Chagelebulu section in the southeastern of Badain Jaran Desert, records five and a half sedimentary cycles consisting of alternations between dune sands or loess and overlying fluviolacustrine during 35 000-25 000 a B.P. Based on the analysis of primary chemical elements(139 samples) —Si O2, Al2O3, TOFE(Fe2O3+Fe O), we found that:1) The variation of the primary chemical element content shows five and a half chemical element cycles, which are approximately consistent with the sedimentary cycles. 2)Among Si O2, Al2O3, TOFE,(TOFE + Al2O3)/Si O2 and CIA, Si O2 has the highest content in the CGS3a(range:44.98%-90.02%, average: 65.96%), followed by Al2O3(range: 5.17%-15.37%, average: 11.87%), and then TOFE(range: 1.40%-6.90%, average: 4.19%),(TOFE + Al2O3)/Si O2(range: 0.07-0.47, average:0.27) and CIA(range: 39.66-68.26, average: 58.97). 3) The contents of Si O2, Al2O3, and TOFE significantly differ among the different sedimentary facies. The average Si O2 content is higher in the dune sands than in the fluviolacustrine and loess, whereas the average Al2O3, TOFE,(TOFE+Al2O3)/Si O2 and CIA contents are higher in the fluviolacustrine and loess than in the dune sands. This study suggests that the peaks of Si O2 contents and the valleys of Al2O3, TOFE,(TOFE+Al2O3)/Si O2, and CIA contents in the dune sands and loess represent the dominant periods of East Asian winter monsoon, the valleys of Si O2 contents and the peaks of Al2O3, TOFE,(TOFE+Al2O3)/Si O2, and CIA contents in the fluviolacustrine reflect the dominant periods of East Asian summer monsoon.Therefore, we suggest that the CGS3 a segment experienced at least five cold-dry climates and six warm-humid climates during 35 000-25 000 a B.P. Of these, the warm climate fluctuations(23LS, 25 LS, 27 LS, 29 LS, 31 LS,33LS) correspond well to the Dansgaard-Oeschger events(D/O3-D/O8, ie, 25 000 a B.P., 26 000 a B.P., 29 000 a B.P., 31 000 a B.P., 32 000 a B.
关 键 词:巴丹吉林沙漠 查格勒布鲁剖面 CGS3a层段 主元素 季风环境变化
分 类 号:P532[天文地球—古生物学与地层学]
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