Aeolian deposits at the southeastern margin of the Tengger Desert (China): Implications for surface wind strength in the Asian dust source area over the past 20,000years
Aeolian deposits at the southeastern margin of the Tengger Desert (China): Implications for surface wind strength in the Asian dust source area over the past 20,000years
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DOI：
10.1016/j.palaeo.2009.12.005
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发表时间：
2010-02
期刊：
影响因子：
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通讯作者：
M. Qiang;Fahu Chen;Zhen-Ting Wang;Guang-ming Niu;Lei Song
中科院分区：
文献类型：
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作者：
M. Qiang;Fahu Chen;Zhen-Ting Wang;Guang-ming Niu;Lei Song
独立的粉尘源数据在理解地质时期大气粉尘负荷的变化方面发挥着重要作用。腾格里沙漠东南缘（香山剖面）风沙沉积物的主要元素组成和粒度特征表明，该沉积物是沙尘暴过程中风沙物质从沙尘源区（沙漠）向沙尘沉积区（黄土高原）输送的中间产物。利用XS剖面的40μm以上和63-178μm的组分以及SiO_2/TiO_2比值作为代用指标，重建了近20 kyr的地面风场。结果表明，19.1 ~ 11.4kyr，地面风强得多，波动剧烈。全新世开始后，风逐渐减弱，并在4.0 - 3.5kyrBP之间达到最小值。2.5kyrBP后，地面风急剧增加。亚洲沙尘源区的地面风与中国黄土沉积记录的冬季风强度变化基本一致。此外，从19.1到11.4 kyr的更强的地面风与格陵兰冰芯确定的高矿物尘埃浓度相一致，除了Bölling-Allerød时期（B/A），当时大气尘埃可能已经被增强的全球水文循环冲洗掉，尽管尘埃仍然从源区排放。这表明，在晚冰期，沙尘源区较强的地面风可以增强大气沙尘负荷。在全新世减弱的地面风制度可能大大有助于减少尘埃浓度的远程尘埃记录。研究区42.5kyrBP以来的古环境变化与邻近记录基本一致。然而，42.5-19.1kyrBP可能的温暖和潮湿仍然需要验证。
Independent dust provenance data play an important role in understanding changes in the atmospheric dust loading over geological time. Major elemental compositions and grain-size characteristics of the aeolian deposits (Xiangshan (XS) section) at the southeastern margin of the Tengger Desert in northwestern China demonstrate that the deposits are an intermediate product of the transportation of aeolian materials from the dust source area (deserts) to the dust depositional regions (Chinese Loess Plateau) that were likely formed by dust storm processes. The >40μm and 63–178μm fractions and the ratio of SiO2/TiO2of the XS section were used as proxies to reconstruct the surface wind regime over the last 20kyr. The results show that the surface winds were much stronger and fluctuate acutely from 19.1 to 11.4kyr. The winds gradually attenuated after the beginning of the Holocene and reached a minimum between 4.0 and 3.5kyrBP. A sharp increase in surface winds occurred after 2.5kyrBP. The surface winds in the Asian dust source area are largely consistent with the changes in winter monsoon strength documented by the Chinese loess deposits. Also, the stronger surface winds from 19.1 to 11.4kyr coincide with the high mineral dust concentration determined from the Greenland ice core, except for the period of Bölling–Allerød (B/A), when the atmospheric dust may have been washed out by enhanced global hydrological cycles although dust was still emitted from source areas. This suggests that the stronger surface winds in dust source areas can enhance the atmospheric dust loadings during the late glacial. The weakening surface wind regime during the Holocene may have greatly contributed to the decrease in dust concentration of the remote dust records. The paleo-environmental changes in the study area since 42.5kyrBP are broadly in agreement with other adjacent records. However, the possible warm and humid spell of 42.5–19.1kyrBP still requires verification.