A three-dimensional model of near-surface shear-wave velocity in the deep alluvial basin underlying the metropolitan area of Las Vegas, Nevada （USA）, is being developed for earthquake site response projections. The ...A three-dimensional model of near-surface shear-wave velocity in the deep alluvial basin underlying the metropolitan area of Las Vegas, Nevada （USA）, is being developed for earthquake site response projections. The velocity dataset, which includes 230 measurements, is interpolated across the model using depth-dependent correlations of velocity with sediment type. The sediment-type database contains more than 1 400 well and borehole logs. Sediment sequences reported in logs are assigned to one of four units. A characteristic shear-wave velocity profile is developed for each unit by analyzing closely spaced pairs of velocity profiles and well or borehole logs. The resulting velocity model exhibits reasonable values and patterns, although it does not explicitly honor the measured shear-wave velocity profiles. Site response investigations that applied a preliminary version of the velocity model support a two-zone ground-shaking hazard model for the valley. Areas in which clay predominates in the upper 30 m are predicted to have stronger ground motions than the rest of the basin.展开更多
The man-induced sediment disaster includes material erosion, transportation and accumulation by human activities. It possesses special attribute in sociology and disaster science. In accordance with human activities, ...The man-induced sediment disaster includes material erosion, transportation and accumulation by human activities. It possesses special attribute in sociology and disaster science. In accordance with human activities, geomorphologic location, behavior and particular, the man-induced sediment disaster can be divided into 4 types: the drainage network, slope and gully, channel and plain-estuary-coastline. Each type includes erosion, transportation, accumulation, complexity and cascading. Based on human activity, geomorphology, sediment mechanics and catastrophology, the man-induced sediment disaster is characterized as follows: (1) accelerating tendency with geographical zoning back-ground; (2) non-order characters by blind action without special technical training; (3) gradually and sharply changing with human environment vibration; and (4) complexity and non-linear figure, etc. One of the reasons leading to man-induced sediment disaster is human environment vibration.展开更多
The sediment hosted disseminated gold deposits in the Qinling region are of sedimentation slight metamorphic origin superimposed by hydrothermal reworking at moderate low temperatures and are well comparable with the ...The sediment hosted disseminated gold deposits in the Qinling region are of sedimentation slight metamorphic origin superimposed by hydrothermal reworking at moderate low temperatures and are well comparable with the typical Carlin gold deposits in the United States. In view of the confusing concept concerning the \!sediment hosted" and \!Carlin type" gold deposits, the authors propose that the term \!sediment hosted gold deposit" should be used in a broad sense which encompasses at least the four subtypes, i.e., the Carlin type, the metamorphic fine clastic type, the hydrothermal sedimentary type and the vein type. In other words, the \!Carlin type" should not be used as a synonym for \!sediment hosted" but is recommended as a subtype under the general category of \!sediment hosted gold deposits".展开更多
Through the scientific investigation on Lushan for a long time,detailed studies have been carried out on the geologic stratum section of Late Quaternary in Dajiaochang. The series age data of complete stratigraphic se...Through the scientific investigation on Lushan for a long time,detailed studies have been carried out on the geologic stratum section of Late Quaternary in Dajiaochang. The series age data of complete stratigraphic section and full time formation since 400 kaBP were based on the results of the analyses using the dating methods with various instruments such as the ancient geomagnetism,electronics spin resonance(ESR),36Cl and luminescence dating,etc. Corresponding to these data,it identified the paleomagnetic polarity events including Biwa-Ⅲ event(320 kaBP),Biwa-Ⅱevent(260 kaBP),Biwa-Ⅰevent(180 kaBP,scarcity due to the disturbance of the iron dish),Blake event(100 kaBP) and Laschamp event(20 kaBP,didn’t grow due to the activities of the surface), etc. Combined with the sequence stratigraphy,layer type characteristics and its sediment environment,the stratigraphic can be divided into 4 stages of development respectively:Stage Ⅰis the climate period of glacial epoch(200~400 kaBP);stage Ⅱis the climate period of interglacial epoch(100~200 kaBP);stage Ⅲis the climate period of periglacial epoch(10~100 kaBP);stage Ⅳis the climate period of postglacial epoch(0~10 kaBP).展开更多
The geology, sediment and soil studies are important due to its significant impacts on agriculture, mining, constructions materials, industries, environment, ground water percolation, air pollution, surface and ground...The geology, sediment and soil studies are important due to its significant impacts on agriculture, mining, constructions materials, industries, environment, ground water percolation, air pollution, surface and ground water pollutions, earthquakes and geo-hazards in Afghanistan. In this research, we studied petrography, Sediment, tectonic structures, soil fraction selection by using hydrometer, sieving analysis, and geological mapping. Results show different kinds of metamorphic rocks of low grade and medium grade metamorphisms, Garnete mica Schist, Garnete Schist, Quarsite, different types of minerals among rocks. Further, type of sediment consisting residual angular (Autochthonous) and rounded (Allochthonous) transported by water, among sediments consisting Garnete, Gneiss, Schist, Quarsite, Biotite and consisting different type of sizes boulders, Cobble, Granule, Sand, Silt. Hydrometer analysis shows different types of soil clayey loam, sandy loam, silty loam. Moreover, Geological mapping shows complex tectonic structures like joints, cracks, faults, folds, anticline and syncline. The obtained<i> </i><span style="font-family:Verdana;">results suggest that the petrography, sediments and soil researches can be used efficiently for catchments of the Kabul Basin and other basins in Afghanistan.</span>展开更多
基金supported by the U.S. Department of Energy(Contract No. DE-FG52-03NA99204)
文摘A three-dimensional model of near-surface shear-wave velocity in the deep alluvial basin underlying the metropolitan area of Las Vegas, Nevada （USA）, is being developed for earthquake site response projections. The velocity dataset, which includes 230 measurements, is interpolated across the model using depth-dependent correlations of velocity with sediment type. The sediment-type database contains more than 1 400 well and borehole logs. Sediment sequences reported in logs are assigned to one of four units. A characteristic shear-wave velocity profile is developed for each unit by analyzing closely spaced pairs of velocity profiles and well or borehole logs. The resulting velocity model exhibits reasonable values and patterns, although it does not explicitly honor the measured shear-wave velocity profiles. Site response investigations that applied a preliminary version of the velocity model support a two-zone ground-shaking hazard model for the valley. Areas in which clay predominates in the upper 30 m are predicted to have stronger ground motions than the rest of the basin.
基金Joint project by National Natural Science Foundation of China and the Ministry of Water Resources,No.59890200National Natural Science Foundation of China, No.48870008
文摘The man-induced sediment disaster includes material erosion, transportation and accumulation by human activities. It possesses special attribute in sociology and disaster science. In accordance with human activities, geomorphologic location, behavior and particular, the man-induced sediment disaster can be divided into 4 types: the drainage network, slope and gully, channel and plain-estuary-coastline. Each type includes erosion, transportation, accumulation, complexity and cascading. Based on human activity, geomorphology, sediment mechanics and catastrophology, the man-induced sediment disaster is characterized as follows: (1) accelerating tendency with geographical zoning back-ground; (2) non-order characters by blind action without special technical training; (3) gradually and sharply changing with human environment vibration; and (4) complexity and non-linear figure, etc. One of the reasons leading to man-induced sediment disaster is human environment vibration.
文摘The sediment hosted disseminated gold deposits in the Qinling region are of sedimentation slight metamorphic origin superimposed by hydrothermal reworking at moderate low temperatures and are well comparable with the typical Carlin gold deposits in the United States. In view of the confusing concept concerning the \!sediment hosted" and \!Carlin type" gold deposits, the authors propose that the term \!sediment hosted gold deposit" should be used in a broad sense which encompasses at least the four subtypes, i.e., the Carlin type, the metamorphic fine clastic type, the hydrothermal sedimentary type and the vein type. In other words, the \!Carlin type" should not be used as a synonym for \!sediment hosted" but is recommended as a subtype under the general category of \!sediment hosted gold deposits".
基金Open Foundation for State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,Chinese Academy of Sciences(No.SKLLQG0701)Hunan Province Key Subject Construction Item(No.ZRDL0701)Open Foundation for State Key Laboratory of Continental Dynamics,Northwest University(No.DL2006001)
文摘Through the scientific investigation on Lushan for a long time,detailed studies have been carried out on the geologic stratum section of Late Quaternary in Dajiaochang. The series age data of complete stratigraphic section and full time formation since 400 kaBP were based on the results of the analyses using the dating methods with various instruments such as the ancient geomagnetism,electronics spin resonance(ESR),36Cl and luminescence dating,etc. Corresponding to these data,it identified the paleomagnetic polarity events including Biwa-Ⅲ event(320 kaBP),Biwa-Ⅱevent(260 kaBP),Biwa-Ⅰevent(180 kaBP,scarcity due to the disturbance of the iron dish),Blake event(100 kaBP) and Laschamp event(20 kaBP,didn’t grow due to the activities of the surface), etc. Combined with the sequence stratigraphy,layer type characteristics and its sediment environment,the stratigraphic can be divided into 4 stages of development respectively:Stage Ⅰis the climate period of glacial epoch(200~400 kaBP);stage Ⅱis the climate period of interglacial epoch(100~200 kaBP);stage Ⅲis the climate period of periglacial epoch(10~100 kaBP);stage Ⅳis the climate period of postglacial epoch(0~10 kaBP).
文摘The geology, sediment and soil studies are important due to its significant impacts on agriculture, mining, constructions materials, industries, environment, ground water percolation, air pollution, surface and ground water pollutions, earthquakes and geo-hazards in Afghanistan. In this research, we studied petrography, Sediment, tectonic structures, soil fraction selection by using hydrometer, sieving analysis, and geological mapping. Results show different kinds of metamorphic rocks of low grade and medium grade metamorphisms, Garnete mica Schist, Garnete Schist, Quarsite, different types of minerals among rocks. Further, type of sediment consisting residual angular (Autochthonous) and rounded (Allochthonous) transported by water, among sediments consisting Garnete, Gneiss, Schist, Quarsite, Biotite and consisting different type of sizes boulders, Cobble, Granule, Sand, Silt. Hydrometer analysis shows different types of soil clayey loam, sandy loam, silty loam. Moreover, Geological mapping shows complex tectonic structures like joints, cracks, faults, folds, anticline and syncline. The obtained<i> </i><span style="font-family:Verdana;">results suggest that the petrography, sediments and soil researches can be used efficiently for catchments of the Kabul Basin and other basins in Afghanistan.</span>
