| Response of grain size of Quaternary gravels to climate and tectonics in the northern Tibetan Plateau |
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| 作者姓名： | FU KaiDao FANG XiaoMin GAO JunPing HAN WenXia & LI LiLi MOE National Laboratory of Western China's Environmental Systems & College of Resource and Environment Lanzhou University Lanzhou China Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China |
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| 作者单位： | FU KaiDao1，FANG XiaoMin2，1，GAO JunPing1，HAN WenXia1 & LI LiLi 1 MOE National Laboratory of Western China's Environmental Systems & College of Resource and Environment，Lanzhou University，Lanzhou 730000，China; 2 Institute of Tibetan Plateau Research，Chinese Academy of Sciences，Beijing 100085，China |
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| 基金项目： | 国家自然科学基金;国家重点基础研究发展计划(973计划);中国科学院院长基金 |
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| 摘 要： | The widely distributed thick gravel deposits along the rim of the Tibetan Plateau have been long thought to be the product of rapid tectonic uplift of the plateau. However, this has been challenged by recent works that suggest these thick gravels may be the result of climate change. In this paper we carried out a detailed field measurement of gravel grain sizes from the Jiuquan and Gobi Gravel Beds in the top of the Laojunmiao section in the Jiuxi Basin in the northern margin of Qilian Mts. (northern Tibetan Plateau). The results suggest that the grain sizes of the Jiuquan and Gobi Gravel Beds over the last 0.8 Ma are characterized by nine coarse-fine cycles having strong 100-ka and 41-ka periodicities that correlate well with the loess-paleosol monsoon record and isotopic global climatic record from deep sea sediments as well as by a long trend of coarsening in gravel grain size. The coarse gravel layers were formed during the warm-humid interglaciations while the fine layers correspond to the cold-dry glaciations. Because the paleoclimate in NW China began to get dramatically drier after the mid-Pleistocene, we think the persistent coarsening of gravel grain size was most probably caused by the rapid uplift of the northern Tibetan Plateau, and that the orbital scale cyclic variations in gravel grain size were driven by orbital forcing factors that were superimposed on the tectonically-forced long-term coarsening trend in gravel size. These findings also shed new light on the interaction results of climate and tectonics in relation to the uplift of the Tibetan Plateau.
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| 收稿时间： | 24 January 2006 |
| 修稿时间： | 29 May 2006 |
Response of grain size of Quaternary gravels to climate and tectonics in the northern Tibetan Plateau |
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| FU KaiDao,FANG XiaoMin,,GAO JunPing,HAN WenXia & LI LiLi MOE National Laboratory of Western China''''s Environmental Systems & College of Resource and Environment,Lanzhou University,Lanzhou ,China, Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing ,China.Response of grain size of Quaternary gravels to climate and tectonics in the northern Tibetan Plateau[J].Science in China(Earth Sciences),2007,50(1):81-91. |
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| Authors: | Fu KaiDao Fang XiaoMin Gao JunPing Han WenXia Li Lili |
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| Institution: | 1. MOE National Laboratory of Western China's Environmental Systems & College of Resource and Environment, Lanzhou University, Lanzhou 730000, China
2. Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China;MOE National Laboratory of Western China's Environmental Systems & College of Resource and Environment, Lanzhou University, Lanzhou 730000, China |
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| Abstract: | The widely distributed thick gravel deposits along the rim of the Tibetan Plateau have been long thought to be the product of rapid tectonic uplift of the plateau. However, this has been challenged by recent works that suggest these thick gravels may be the result of climate change. In this paper we carried out a detailed field measurement of gravel grain sizes from the Jiuquan and Gobi Gravel Beds in the top of the Laojunmiao section in the Jiuxi Basin in the northern margin of Qilian Mts. (northern Tibetan Plateau). The results suggest that the grain sizes of the Jiuquan and Gobi Gravel Beds over the last 0.8 Ma are characterized by nine coarse-fine cycles having strong 100-ka and 41-ka periodicities that correlate well with the loess-paleosol monsoon record and isotopic global climatic record from deep sea sediments as well as by a long trend of coarsening in gravel grain size. The coarse gravel layers were formed during the warm-humid interglaciations while the fine layers correspond to the cold-dry glaciations. Because the paleoclimate in NW China began to get dramatically drier after the mid-Pleistocene, we think the persistent coarsening of gravel grain size was most probably caused by the rapid uplift of the northern Tibetan Plateau, and that the orbital scale cyclic variations in gravel grain size were driven by orbital forcing factors that were superimposed on the tectonically-forced long-term coarsening trend in gravel size. These findings also shed new light on the interaction results of climate and tectonics in relation to the uplift of the Tibetan Plateau. |
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| Keywords: | Tibetan Plateau Jiuxi Basin gravels grain sizes climate changes tectonics |
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