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Geochemical, mineralogical and sedimentological studies on the Taklimakan Desert sands 总被引：7，自引：0，他引：7
Major-element composition, mineral composition and grain-size distribution have been studied for Quaternary aeolian sediments from the Taklimakan Desert, north-western China, together with the variation of chemical and mineralogical compositions of different grain-size fractions. Aeolian sediments from the Taklimakan Desert have higher ratios of feldspar/quartz and calcite/quartz, finer grain size, poorer roundness of quartz and feldspar grains and lower abundances of frosted quartz, than found in aeolian sediments from other deserts such as the Saudi Arabian Desert. In spite of these immature mineralogical and sedimentological features, the aeolian sediments from the Taklimakan Desert show low regional variations in major-element and mineral compositions and are homogenized. These observations confirm that two processes, glacial activity within surrounding mountains and aeolian activity at the Tarim Basin, are important in the homogenization of the Taklimakan Desert sands. Taklimakan Desert sediments are constantly and effectively supplied from basement rocks in the surrounding mountains by glacial erosion. The supplied sediments are further homogenized by aeolian activity in the desert and are partly blown away, serving as the source of Chinese aeolian loess. Compositional differences are observed between loess (mainly 10–40 μm particles) and the <45 μm fraction of the Taklimakan Desert sediments, as well as between loess and whole rock of the Taklimakan Desert sediments. These observations provide constraints for precise modelling of loess formation, and for assessment of the chemical composition of the upper continental crust based on the chemical composition of aeolian loess. 相似文献
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Earthquake-induced jumping of Bell Houses evidenced in epicentral areas of two earthquakes is discussed here. The earthquakes are the 1995 Hyogoken-nanbu, Japan earthquake and the 1909 Anegawa, Japan earthquake. Site-investigation was conducted to estimate vibration characteristics of the House and the ground. A series of shaking-table experiments, using models of a Bell House, demonstrated that the jumping followed by remarkable displacement can take place even by horizontal ground motion alone, when the strong motion is abruptly applied in the direction diagonal to the framework of the Bell House. The jumping process in the model experiment seems to be consistent with observations at real Bell Houses. © 1997 John Wiley & Sons, Ltd. 相似文献
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