| 北京邻区1.2Ma以来黄土沉积及其对东部沙漠扩张的指示 |
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| 引用本文： | 熊尚发,丁仲礼,刘东生.北京邻区1.2Ma以来黄土沉积及其对东部沙漠扩张的指示[J].海洋地质与第四纪地质,1999,19(3):67-73. |
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| 作者姓名： | 熊尚发 丁仲礼 刘东生 |
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| 作者单位： | 中国科学院,地质研究所,北京100029 |
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| 摘 要： | 远离黄土高原主体的北京邻区延－怀－涿盆地沉积了总厚度超过１００ｍ的厚层黄土，其底部可见Ｌ１５，对应的年龄约为１．２Ｍａ。对剖面进行的粒度分析揭示，在０．２５Ｍａ（氧同位素８阶段）前后，黄土层的中值粒径发生了突变，从平均２０～３０μｍ变为４５～６０μｍ，相应粗颗粒（＞６５μｍ）比例也大幅增加，从１５％～２５％增至４０％～５０％。这一变化是以往在远离沙漠源区的黄土沉积中所未见的，表明我国北部沙漠和戈壁干旱化程度和范围在这一时间发生了重大的变化，从而使北京黄土沉积区和源区的距离出现了突变。
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| 关 键 词： | 黄土 粒度 沙漠扩张 北京邻区 |
| 修稿时间： | 1999-03-05 |
LOESS DEPOSITS IN BEIJING REGION SINCE LAST 1.2 Ma AND DESERT EXPANSION OVER NORTHERN CHINA |
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| XIONG Shangfa,DING Zhongli,LIU Tungsheng.LOESS DEPOSITS IN BEIJING REGION SINCE LAST 1.2 Ma AND DESERT EXPANSION OVER NORTHERN CHINA[J].Marine Geology & Quaternary Geology,1999,19(3):67-73. |
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| Authors: | XIONG Shangfa DING Zhongli LIU Tungsheng |
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| Abstract: | The analyses of a loess sequence in Beijing exhibit an abrupt shift in grain size in 0 25MaBP.This shift is not documented in previous studies on the sections far from the dust source areas,implying an expansion of desert boundary over northern China near Beijing region during this period.It is difficult to explain this expansion of desert in terms of orbital forcing or ice volume forcing. |
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| Keywords: | loess grain size desert expansion near Beijing |
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