摘要
对2009年9月23日悉尼特强沙尘暴和2010年4月兰州沙尘暴样品进行了磁学参数和粒度测量。结果表明:悉尼尘暴样品中磁性矿物含量远远低于兰州样品。磁性矿物种类略有不同,兰州样品主要含有磁铁矿、磁赤铁矿,可能含有赤铁矿;悉尼样品除了上述矿物外,还含有针铁矿。悉尼样品比兰州样品的磁性矿物颗粒要细。悉尼样品的粒度分布曲线呈现四峰态,粒度曲线呈现宽扁形态;兰州样品呈现三峰态,粒度曲线则呈窄高的形态。沙尘暴样品与源区样品磁学性质的大相径庭及粒度曲线的多峰态分布都说明了沙尘暴物源的非惟一性。此外,将兰州沙尘暴样品与九州台黄土-古土壤样品的粒度进行了比较,结果显示,1～10μm组分含量的增加及10～20μm组分含量的减少主要与不稳定矿物的物理化学风化过程有关,0.02～1μm组分含量增加的主要原因是新矿物的生成及不稳定矿物的风化。沙尘暴样品与黄土-古土壤样品的粒度分布曲线具有一定的相似性,说明现代沙尘暴事件是地质时期风尘活动的持续,现代风积作用仍在继续。
Measurements of magnetic properties and particle size were carried out for sand-storm samples collected in Sydney on September 23, 2009 and in Lanzhou in April 2010. The results showed that the mag- netic content of Lanzhou sample was much higher than that of Sydney sample. Both samples differed slightly in mineralogy. Lanzhou sample contained maghemite, hematite and possibly hematite. Besides these miner- als, Sydney sample likely contained goethite. The magnetic grain size of Sydney sample was finer than that of Lanzhou sample. As to particle-size distribution, Sydney sample showed a wide and flat curve with four peaks, while Lanzhou sample displayed a narrow curve with three peaks. The great difference in magnetic properties between storm samples and source samples and the multi-peak particle-size distribution curves were all indicative of multisource storms. Furthermore, a comparison of particle size between Lanzhou storm sample and Jiuzhoutai loess samples was made. The results showed that the increase of 1 10 μm component and the decrease of 10--20 μm component were caused by the physical and chemical weathering of unstable minerals, while the increase of 0.02 1 μm component was mainly contributed to the formation of new minerals and the weathering of unstable minerals. The certain similarity of particle size distribution curves between Lanzhou sand-storm sample and loess-paloesol sample, implied a linkage between modern storm events and geological eolian activities.
出处
《中国沙漠》
CSCD
北大核心
2013年第1期231-238,共8页
Journal of Desert Research
基金
国家自然科学基金项目(40830105
41072124
41021091)
教育部博士点基金项目(20070730026)
甘肃省自然科学基金项目(0710KJZA024)资助
关键词
悉尼
兰州
沙尘暴
粒度
磁学性质
沙尘物源
Sydney
Lanzhou
sand storm
particle size
magnetic properties
source of dust
