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排序方式: 共有435条查询结果,搜索用时 15 毫秒
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NIGEL R. J. POOLTON LARS BØTTER-JENSEN ANN G. WINTLE PETER J. YPMA KAREN LUISE KNUDSEN VAGN MEJDAHL BARBARA MAUZ HENRIK E. CHRISTIANSEN JØRGEN JAKOBSEN FINN JØRGENSEN FINN WILLUMSEN 《Boreas: An International Journal of Quaternary Research》1996,25(3):195-208
This article describes the development and performance of an integrated optical sensor system that has been designed for rapid analysis of split sediment cores. The primary aim of the system is to obtain information based on optically stimulated luminescence (OSL) techniques; these provide a record of the accrued radiation dose of material since deposition. Particularly after suitable normalization, the luminescence signal recorded along the length of the core will provide information on the relative age of the sediment. Two wavelengths of stimulation are used (infra-red and green) and these probe the feldspar, and combined feldspar and quartz components of the sediment respectively; the ratio of the two signals can thus provide some indication of relative changes in the silicate mineralogy. A secondary use of the system is for optical reflectance measurements. With the addition of a monochromator, optical reflectance spectroscopy can be applied to obtain additional information on down-core mineralogical changes. In this article we describe technical aspects of the sensor system, discuss measurement techniques and consider the relevance of data obtained. Two examples of sediment cores are presented, which demonstrate the applicability of the instrument. 相似文献
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Geology in the Falkland Islands 总被引:2,自引:0,他引:2
RICHARD CLARK EMMA EDWARDS STEPHEN LUXTON TOM SHIPP & PETER WILSON 《Geology Today》1995,11(6):217-223
In the next few years we are likely to hear and learn much about the offshore geology of the Falkland Islands as exploratory drilling for hydrocarbons begins. The offshore geology may become better known than the onshore, of which there has been little detailed investigation in the 200+ years since settlements were established. Here we outline the history of geological investigations and present information gathered during recent fieldwork. 相似文献
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JEF VANDENBERGHE PETER VAN DEN BROEK 《Boreas: An International Journal of Quaternary Research》1982,11(4):299-315
In three excavations in the southern Netherlands and northern Belgium, the Weichselian convolutions in fine sand, silt and clay deposits were investigated, and an attempt was made towards a semi-quantitative approach to some sediment parameters. This, together with a detailed field survey, enabled interpretation of the deformations as forms of periglacial loadcasting. They originated from the time of permafrost degradation when large quantites of water were available. The amplitude of the involutions can be related to the depth of the permafrost table at that time. During the weichselian, two periods occurred in which this involution process could have been active 相似文献
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Two-dimensional turbulence properties of the ECMWF reanalyses 总被引:1,自引:0,他引:1