Mineralogical and morphological properties of individual dust particles in ice cores from the Tibetan Plateau
Mineralogical and morphological properties of individual dust particles in ice cores from the Tibetan Plateau
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DOI：
10.1017/jog.2016.8
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发表时间：
2016-02
影响因子：
3.4
通讯作者：
Guangjian Wu;Xuelei Zhang;Chenglong Zhang;Tianli Xu
中科院分区：
文献类型：
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作者：
Guangjian Wu;Xuelei Zhang;Chenglong Zhang;Tianli Xu
摘要利用场发射扫描电子显微镜和能量色散X射线能谱仪（FESEM-EDS），分析了青藏高原北方（敦德）、西部（慕士塔格塔）和东南部（帕隆-藏博）冰芯中单个不溶性尘埃颗粒的矿物学和形态学特征，以揭示长距离传输的亚洲尘埃的类似物。结果表明，沙尘颗粒物主要由石英（17- 36%，数量丰度）、粘土（37-48%）和长石（12-18%）组成。伊利石和高岭石是主要的粘土种类，而很少观察到高岭石。对于这三个地点，矿物组合的区域差异显着，特别是石英、绿泥石和白云母物种的丰度，反映了这些尘埃颗粒的区域来源及其源区的气候状况。粘土中的氧化物比值反映了不同源区颗粒的风化强度，青藏高原西部和北方的K2 O/（SiO2 + Al 2 O3）值较高。单个颗粒的纵横比和圆度分布分别为1.48和1.53。长径比与圆度之间没有显著的相关性，石英和长石颗粒的长径比分布较窄。白云母颗粒的粒度较粗，而白云母颗粒的粒度较细。
ABSTRACT Using a field emission scanning electron microscope and energy-dispersive X-ray spectrometer (FESEM−EDS), individual insoluble dust particles in ice cores recovered from the northern (Dunde), western (Muztagata) and south-eastern (Palong-Zangbo) Tibetan Plateau were analysed in order to reveal the mineralogical and morphological characteristics of the analogue of long-range transported Asian dust. The results reveal that the dust particles are mainly composed of quartz (17–36%, number abundance), clay (37–48%) and feldspar (12–18%). Illite and chlorite are the dominant clay species, while kaolinite is rarely observed. For the three sites, regional differences in the mineral assemblages are significant, in particular the abundance of quartz, chlorite and muscovite species, reflecting the regional provenance of these dust particles and the climatic regime in their source areas. Oxide ratios in clays indicate different weathering strengths of the particles in their source regions, with a higher K2O/(SiO2 + Al2O3) in the western and northern Tibetan Plateau. The individual particles have modes of 1.48 and 1.53 in the aspect ratio and circularity distribution respectively. No significant relationship between aspect ratio and circularity was found. Quartz and feldspar particles have a narrow aspect ratio distribution. Muscovite particles have the coarsest grain size, while chlorite particles have the finest.