| 晚第三纪中国西北干旱化的发展及其与北极冰盖形成演化和青藏高原隆升的关系 |
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| 引用本文： | 郭正堂,彭淑贞,郝青振,陈习慧,刘东生.晚第三纪中国西北干旱化的发展及其与北极冰盖形成演化和青藏高原隆升的关系[J].第四纪研究,1999,19(6):556-567. |
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| 作者姓名： | 郭正堂 彭淑贞 郝青振 陈习慧 刘东生 |
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| 作者单位： | 中国科学院地质与地球物理研究所, 北京 100029 |
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| 基金项目： | 国家自然科学基金49725206;国家重点基础科研规划青藏专项经费资助项目 |
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| 摘 要： | 对甘肃酉峰晚第三纪红土标准剖面的研究揭示出,该区红土下部(６．２ＭａＢ．Ｐ．前)是红化的土壤物质与其它物质一起经水流搬运(坡积作用为主)再堆积的产物；中部(６．２～３．４ＭａＢ．Ｐ．)未发现再搬运的痕迹,是风尘堆积经风化和频繁地下水位波动作用所形成,不具明显的土壤发生学层次,其中的碳酸盐富积层不是成壤碳酸盐,而与地下水作用密切相关；上部(３４～２．６ＭａＢ．Ｐ．)是典型的风尘堆积－土壤序列。由于中国西北和中亚干旱区的存在是黄河中游风尘堆积的前提条件,该区风尘物质的堆积起始于６．２ＭａＢ．Ｐ．前后标志着源区干旱化的加剧,并已达到相当高的程度。对整个序列的分析表明,源区干旱化程度在６．２～５．４ＭａＢ．Ｐ．期间较高,此后降低,在３．４ＭａＢ．Ｐ．和２．６ＭａＢ．Ｐ．又两次显著增强。上述历史与北极冰盖的起源和演化历史具有高度的一致性,若干重大转变与青藏高原隆升也有时代上的耦合性。本文认为,北极冰盖的形成演化和高原隆升都是中国西北和中亚地区干旱化发展的重要驱动因素,二者对西伯利亚高压的形成和发展的影响及高原对暖湿气流的阻挡可能是导致于旱化的重要途径。
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| 关 键 词： | 第三纪 干旱化 季风 青藏高原 红土 |
| 收稿时间： | 1999-09-16 |
| 修稿时间： | 1999-09-17 |
LATE TERTIARY DEVELOPMENT OF ARIDIFICATION IN NORTHWESTERN CHINA: LINE WITH THE ARCTIC ICE-SHEET FORMATION AND TIBETAN UPLIFTS |
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| Institution: | Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029 |
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| Abstract: | The Xifeng red-earth sequence, a type section for the eastern loess region, isstudied based on thin section analyses, sedimentological, and geochemical to addressits origin and climatic implication. The result shows that this formation consists ofthree parts. The lower Part (> 6.2 Ma B. P.) is a fluvial-alluvial deposit; themiddle part (from 6.2 to 3.4 Ma B. P.) was derived from eolian dust deposition, asstated in earlier study, but significanhy affected by weathering processes andgroundwater oscillations. The upper part (from 3.4 to 2.6 Ma B. P.) is a typicaleolian formations, similar to the Quaternary loess-soil sequence. Since eolian dustdeposits at the middle Reaches of the Huanghe River was mainly transported from thedesert in northwestem China, we interpret the eolian origin of the red-earthformation started at 6.2 Ma B. P. as an indication of the strengthening of thearidification on the Asian continent.Variations of the eolian grain-size in the middle and upper part of the sequenceindicate that continental aridity were stronger from 6.2 to 5.4 Ma B. P., weaker from 5.2to 3.4 Ma B. P. and then significantly sdtrengthened at 3.4 Ma B. P. and 2.6 Ma B. P.,respectively. These changes are highly consistent with the North Pacific eolian record. amarine record of Asian continental climate, and also coupled with the Arctic ice-sheetdevelopment. These results suggest that the Asian aridification were strongly forced bythe Arctic ice-sheet development, probably through the strengthening of the Siberian High.The aridification occurred at 3.4 Ma B. P. and 2.6 Ma B. P. were also synchronouswith intense-uplift of the Qinghai-Xizang Plateau. suggesting a causal link. |
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| Keywords: | Tertiary aridification monsoon Qinghai-Xizang Plateau red-eartj |
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