GPS在易门1∶5万水系沉积物测量质量监控中应用   总被引：1，自引：0，他引：1  

常旭坤 《云南地质》2010,29(4):461-462,428

GPS的单点绝对定位及航迹功能应用到水系沉积物地球化学测量野外施工质量监控,能有效避免人为因素导致点位失真、采样随机性大等问题,提高野外定点精度,并可及时了解野外进度及采样点的到位情况。  相似文献   

Petrology,structure and age of the Rough Point sill,Donegal     

R. Elsdon 《Geological Journal》1986,21(2):151-168

The Rough Point sill, which is one of the thickest of a large number of sills intruded into the Appin Group metasediments of the Dalradian sequence in north Donegal, contains a number of internal features including mafic:felsic banding, pegmatite bands and significant variations in grain size. There are also appreciable variations in mineralogy, particularly the proportions of plagioclase and amphibole, and in the major and trace element chemistry. Together these features indicate that the sill is, like the metasediments which it intrudes, inverted, and is therefore older than the Caledonian F₂ structures which caused the inversion. Disruption of the sediments at the sill contact is also earlier than the F₂ event. The timing of the basic magmatic episode together with the geochemistry of the sill invite comparison with the metadolerites of the southwest Highlands of Scotland.  相似文献   

Sedimentation in a meandering gravel-bed river: The River Tywi,South Wales     

Simon A. Smith 《Geological Journal》1989,24(3):193-204

Previous studies of meandering gravel-bed rivers have illustrated a wide range of bar types. The River Tywi of South Wales shows that significant variations of accretionary style can also occur within a single river. There is a downstream decrease in the proportion of lateral bars to point bars and changes in the morphological characteristics of these point bars. Three types are recognized: simple, linguoid and multi-unit point bars. Sedimentation on the concave sides of meander bends is locally important. The changes of bar type are accompanied by different styles of channel behaviour. The River Tywi is interpreted to have deposited multilateral gravel sheets, composed of partially reworked and abandoned bars and dissected by palaeochannels and sloughs. Bar deposits consist of parallel-bedded gravel, inclined laterally-accreted gravel, local angle-of-repose foresets and inclined lenses of heterolithic beds. The proportion of the various sedimentary structures and the geometry of the abandoned bars varies along the Tywi valley because of the patterns of bar distribution and channel behaviour. The deposits of this river have strong affinities with Tertiary sequences in the Italian Apennines, previously interpreted as the deposits of meandering gravel-bed rivers. This type of river is not readily distinguished from ‘Scott type’ braided streams in the geological record, unless exposures are particularly good. In this respect, the presence of abundant, inclined heterolithic wedges and lenses may be a useful diagnostic criterion.  相似文献