The Balfour Formation was subdivided into five members based on lithological variation that is characterized by alternating sandstone-and mudstone -dominated members.The sandstone dominated Oudeberg and Barberskrans m...The Balfour Formation was subdivided into five members based on lithological variation that is characterized by alternating sandstone-and mudstone -dominated members.The sandstone dominated Oudeberg and Barberskrans members are composed of lithofacies that range from intraformational conglomerates to fine-grained sediments,whereas the mudstone dominated members(Daggaboersnek, Elandsberg and Palingkloof) are dominated by the fine-grained facies(Fm and F1).Petrography,geochemistry and palaeocurrent analysis indicated that the source rock of the Balfour Formation was to展开更多
By taking the Yong River for example in this paper, based on the multiple measured data during 1957 to 2009, the change process of runoff, tide feature, tidal wave, tidal influx and sediment transport are analyzed. Th...By taking the Yong River for example in this paper, based on the multiple measured data during 1957 to 2009, the change process of runoff, tide feature, tidal wave, tidal influx and sediment transport are analyzed. Then a mathematical model is used to reveal the influence mechanism on hydrodynamic characteristics and sediment transport of the wading engineering groups such as a tide gate, a breakwater, reservoirs, bridges and wharves, which were built in different periods. The results showed the hydrodynamic characteristics and sediment transport of the Yong River changed obviously due to the wading engineering groups. The tide gate induced deformation of the tidal wave, obvious reduction of the tidal influx and weakness of the tidal dynamic, decrease of the sediment yield of flood and ebb tide and channel deposition. The breakwater blocked estuarine entrances, resulting in the change of the tidal current and the reduction of the tidal influx in the estuarine area. The large-scale reservoirs gradually made the decrease of the Yong River runoff. The bridge and wharf groups took up cross-section areas, the cumulative affection of which caused the increase of tidal level in the tidal river.展开更多
Settling velocity is a fundamental parameter in sediment transport dynamics. For uniform particles, there are abundant formulas for calculation of their settling velocities. But in natural fields, sediment consists of...Settling velocity is a fundamental parameter in sediment transport dynamics. For uniform particles, there are abundant formulas for calculation of their settling velocities. But in natural fields, sediment consists of non-uniform particles. The interaction among particles is complex and should not be neglected. In this paper, based on the analysis of settling mechanism of non-cohesive and non-uniform particles, a theoretical model to describe settling mechanism is proposed. Besides suspension concentration and upward turbulent flow caused by other particles, collision among particles is another main factor influencing settling velocity. By introducing the collision theory, equations of fall velocity before collision, collision probability, and fall velocity after collision are established. Finally, a formula used to calculate the settling velocity of non-cohesive particles with wide grain gradation is presented, which agrees well with the experimental data.展开更多
The settling of sediments is an accelerative process in which the concentration of the main sediments zone will heavily influence settling velocity, but the explicit relationship between the concentration and settling...The settling of sediments is an accelerative process in which the concentration of the main sediments zone will heavily influence settling velocity, but the explicit relationship between the concentration and settling velocity has not been reported in literature. Here a theoretical function was built for the time dependent concentration and time dependent settling velocity of sediments ; then the entire settling process reflecting concentration was shown on the basis of sediments instant-settlement theory and mathematical method. Agreement of computed results and experimental data was found. Several governing parameters, including particle size,particle density,inltial suspended sediments concentration and suspension height, were discussed with a series of calculated velocity curves. The research indicated that (1) the presented concentration-velocity time relationship is rational, (2) settling process of the sediments group with variation of concentration consists of acceleration stage, uniform motion stage and deceleration stage, and (3) particle size, particle density and initial suspended sediments concentration have more influence on the settling velocity than the suspension height and water temperature.展开更多
Methodological problems of climatic reconstruction for different periods of Holocene are discussed on the basis of a multiple group biological analysis on peat-sapropel sediments.The possibility of biological analysis...Methodological problems of climatic reconstruction for different periods of Holocene are discussed on the basis of a multiple group biological analysis on peat-sapropel sediments.The possibility of biological analysis is exemplified by the paleoclimatic reconstruction for Carpathian and Altai Mountain ranges.For the "Skolevsky Beskidy" national park of Carpaty the paleoclimatic scenarios have been drown up aiming at the more precise definition of climatic conditions for the period of mass mountain slope terracing.The stability of terrace systems of various designs in the current climatic conditions has been assessed.It is shown that during periods of humid climate the terraces,whose designs have been focused on drainage,were built.In periods of dry and warm climate the terrace systems capable of accumulating water were built.Both these types of terrace systems are destroyed in nowadays.Only those terrace systems are stable which were adjusted by their builders to contrast variations of precipitation.For Western Altais the paleoclimatic scenario has been done to forecast the safety of the Bronze Age kurgans(burial earth mounds) with permafrost inside the construction.In the Altay region during the Holocene it has revealed two periods of sharp cooling,the peaks of which occurred in the intervals 4500-4300 and 2500-2300 years ago,and two periods of pronounced climatic drying 4900-4700 and 130-70 years ago.Depletion of the algae composition in the layer corresponding to the last period of drying climate indicates a very sharp change in the parameters of moisture and turning the lake into a dry swamp.Periods of cold weather may have contributed to the formation of special ritual traditions of the Sakan tribes that require the frozen ground to bury the dead.The later climate fluctuations identified have not affected the safety of permafrost in burial mounds constructed in the V-III cc BC.展开更多
文摘The Balfour Formation was subdivided into five members based on lithological variation that is characterized by alternating sandstone-and mudstone -dominated members.The sandstone dominated Oudeberg and Barberskrans members are composed of lithofacies that range from intraformational conglomerates to fine-grained sediments,whereas the mudstone dominated members(Daggaboersnek, Elandsberg and Palingkloof) are dominated by the fine-grained facies(Fm and F1).Petrography,geochemistry and palaeocurrent analysis indicated that the source rock of the Balfour Formation was to
基金financially supported by the National Science Foundation for Distinguished Young Scholars of China(Grant No.51125034)the National Natural Science Foundation of China(Grant Nos.51279046 and 50909037)the Fundamental Research Funds for the Central Universities(Grant No.2010B01114)
文摘By taking the Yong River for example in this paper, based on the multiple measured data during 1957 to 2009, the change process of runoff, tide feature, tidal wave, tidal influx and sediment transport are analyzed. Then a mathematical model is used to reveal the influence mechanism on hydrodynamic characteristics and sediment transport of the wading engineering groups such as a tide gate, a breakwater, reservoirs, bridges and wharves, which were built in different periods. The results showed the hydrodynamic characteristics and sediment transport of the Yong River changed obviously due to the wading engineering groups. The tide gate induced deformation of the tidal wave, obvious reduction of the tidal influx and weakness of the tidal dynamic, decrease of the sediment yield of flood and ebb tide and channel deposition. The breakwater blocked estuarine entrances, resulting in the change of the tidal current and the reduction of the tidal influx in the estuarine area. The large-scale reservoirs gradually made the decrease of the Yong River runoff. The bridge and wharf groups took up cross-section areas, the cumulative affection of which caused the increase of tidal level in the tidal river.
文摘Settling velocity is a fundamental parameter in sediment transport dynamics. For uniform particles, there are abundant formulas for calculation of their settling velocities. But in natural fields, sediment consists of non-uniform particles. The interaction among particles is complex and should not be neglected. In this paper, based on the analysis of settling mechanism of non-cohesive and non-uniform particles, a theoretical model to describe settling mechanism is proposed. Besides suspension concentration and upward turbulent flow caused by other particles, collision among particles is another main factor influencing settling velocity. By introducing the collision theory, equations of fall velocity before collision, collision probability, and fall velocity after collision are established. Finally, a formula used to calculate the settling velocity of non-cohesive particles with wide grain gradation is presented, which agrees well with the experimental data.
文摘The settling of sediments is an accelerative process in which the concentration of the main sediments zone will heavily influence settling velocity, but the explicit relationship between the concentration and settling velocity has not been reported in literature. Here a theoretical function was built for the time dependent concentration and time dependent settling velocity of sediments ; then the entire settling process reflecting concentration was shown on the basis of sediments instant-settlement theory and mathematical method. Agreement of computed results and experimental data was found. Several governing parameters, including particle size,particle density,inltial suspended sediments concentration and suspension height, were discussed with a series of calculated velocity curves. The research indicated that (1) the presented concentration-velocity time relationship is rational, (2) settling process of the sediments group with variation of concentration consists of acceleration stage, uniform motion stage and deceleration stage, and (3) particle size, particle density and initial suspended sediments concentration have more influence on the settling velocity than the suspension height and water temperature.
基金supported by the Russian Foundation for Basic Research (Grant No 08-05-92223)
文摘Methodological problems of climatic reconstruction for different periods of Holocene are discussed on the basis of a multiple group biological analysis on peat-sapropel sediments.The possibility of biological analysis is exemplified by the paleoclimatic reconstruction for Carpathian and Altai Mountain ranges.For the "Skolevsky Beskidy" national park of Carpaty the paleoclimatic scenarios have been drown up aiming at the more precise definition of climatic conditions for the period of mass mountain slope terracing.The stability of terrace systems of various designs in the current climatic conditions has been assessed.It is shown that during periods of humid climate the terraces,whose designs have been focused on drainage,were built.In periods of dry and warm climate the terrace systems capable of accumulating water were built.Both these types of terrace systems are destroyed in nowadays.Only those terrace systems are stable which were adjusted by their builders to contrast variations of precipitation.For Western Altais the paleoclimatic scenario has been done to forecast the safety of the Bronze Age kurgans(burial earth mounds) with permafrost inside the construction.In the Altay region during the Holocene it has revealed two periods of sharp cooling,the peaks of which occurred in the intervals 4500-4300 and 2500-2300 years ago,and two periods of pronounced climatic drying 4900-4700 and 130-70 years ago.Depletion of the algae composition in the layer corresponding to the last period of drying climate indicates a very sharp change in the parameters of moisture and turning the lake into a dry swamp.Periods of cold weather may have contributed to the formation of special ritual traditions of the Sakan tribes that require the frozen ground to bury the dead.The later climate fluctuations identified have not affected the safety of permafrost in burial mounds constructed in the V-III cc BC.
