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11.
突出山铜铁矿床赋存于上石炭统底坎尔组火山岩中, 地质特征表明矿床成因为火山热液交代型。矿区玄武岩具有高Al、Na, 贫K、P、Ti的特点, 属于钙碱性系列火山岩。岩石具有轻稀土元素、大离子亲石元素相对富集和高场强元素相对亏损的特点。微量元素特征表明岩石与俯冲带流体作用有关, 经历了橄榄石(±辉石)和铬铁矿的结晶分异作用, 形成于石炭纪弧后盆地环境, 指示铁矿床的成矿环境为弧后盆地环境。矿区闪长岩和钾长花岗岩的锆石LA-ICP-MS U-Pb谐和年龄分别为326.2±1.6 Ma与318.2±2.5 Ma, 均为石炭纪岩浆活动的产物。根据闪长岩、钾长花岗岩、矿体与底坎尔组火山岩的穿插关系, 限定矿床的铁成矿作用时间为底坎尔组火山岩的形成时代, 早于闪长岩的形成时代(326 Ma), 而铜成矿作用时间与闪长岩的形成时代相近或稍晚。 相似文献
12.
阿尔金奇克山东斜长角闪岩岩石地球化学分析显示:岩石SiO_2和Al_2O_3含量较高,分别为46.99%~51.01%和13.85%~15.82%,MgO和FeO~T值为7.00%~7.71%和12.4%~13.5%,属拉斑系列岩石;主量元素MgO对SiO_2、Al_2O_3、CaO、FeO~T关系图及微量元素Cr-Rb和Rb/Nb-Rb/Zr关系图,显示岩石演化过程中曾发生部分熔融和分离结晶作用;轻稀土元素微富集指示岩浆可能经历了10%~20%部分熔融和低程度分离结晶的演化。锆石Lu-Hf同位素特征表明原岩是由较球粒陨石稍分异的地幔岩浆形成,岩浆的液相线温度为1175~1251℃。微区定年揭示其岩石原岩年龄为718±22Ma,变质年龄为502±14Ma。综合分析认为岩石非新太古代产物,而是形成于新元古代Rodinia超大陆汇聚作用之后的伸展期,早古生代经历了阿尔金南缘峰期变质作用,表明此时阿尔金原古特提斯洋已经闭合。 相似文献
13.
Xiqiang Wang Rensheng Chen Guohua Liu Chuntan Han Yong Yang Yaoxuan Song Junfeng Liu Zhangwen Liu Xiaojiao Liu Shuhai Guo Lei Wang Qin Zheng 《水文研究》2019,33(1):66-75
The increase in low flows (winter discharge and minimum monthly discharge), caused primarily by permafrost degradation, is common in high‐latitude permafrost regions, whereas the dynamics of low flows in high‐altitude permafrost regions remain largely unknown. Long‐term discharge data from 28 unregulated catchments in western China were analysed, and the findings showed that winter discharge/minimum monthly discharge significantly increased (p ≤ 0.1) in 82/82%, 55/64%, and 0/0% of the catchments in the higher‐latitude mountain permafrost regions (Tienshan Mountains), mid‐latitude mountain permafrost regions (Qilian Mountains), and mid‐ to low‐latitude plateau permafrost regions (the source regions of the Yangtze and Yellow rivers), respectively. The differences in permafrost type and the distribution of permafrost and alpine cold desert (which is similar to tundra) were found to be the main causes for the different responses in the low flows. The rate of change of low flows (winter discharge and minimum monthly discharge) was negatively and linearly correlated with permafrost coverage when coverage was less than 40% of the catchment area, whereas the low flows changed only slightly when the permafrost coverage exceeded 40%. A significant thickening of the active layer increased the low flows in the lower permafrost‐covered catchments, which are dominated by warm permafrost. However, in the higher permafrost‐covered catchments with cold permafrost and a cold climate, only an increase in permafrost temperature (without a notable thickening of the active layer) occurred, resulting in non‐significant changes in low flows. 相似文献
14.
中国积雪时空变化分析 总被引：3，自引：0，他引：3
结合2001—2010年Aqua与Terra卫星MODIS积雪影像,分析了新疆、青藏高原和东北-内蒙地区积雪的空间稳定性,并探讨了这三大积雪区积雪季节和年际变化特征。结果表明,三大积雪区中新疆积雪空间稳定性最好,东北-内蒙地区次之,青藏高原较差,其稳定性指数分别为0.58、0.38和0.29。三大积雪区积雪年内分配存在显著的季节特征,2001—2010年新疆和东北-内蒙积雪区积雪面积最大值一般出现在1月,偶尔出现在12月,到7月和8月积雪面积很小;青藏高原积雪面积最大值则有可能出现在11—2月,其中以11月出现频率最高,10—3月的积雪面积差异相对其他两个积雪区的变化较小。从年际变化上看,2002年以来三大积雪区及全国稳定积雪面积无明显变化。 相似文献
15.
The probability distribution of the wet season hourly precipitation is the important basis for the study of the precipitation distribution, especially in mountainous areas. Hulu watershed is the study area located in the upper reaches of Heihe River, Qilian Mountains. By adopting the maximum likelihood estimation, the shape parameter α and scale parameter β of 6 stations were obtained with observed wet season (May to September) half hourly data, and different intensity precipitation probability density distribution, cumulative probability density and probability of precipitation and elevation and precipitation relationship were analyzed. The shape parameter α and scale parameter β is significantly negatively correlated, shape parameter α and average hourly precipitation distribution is consistent. Local topography is also an important factor to affect the precipitation redistribution and the probability distribution of precipitation in Hulu watershed. In addition to the increase of precipitation events, the probability of 1~3 mm mm/h precipitation increases with the altitude, which is the main reason for the increase of precipitation with altitude. 相似文献
16.
Land surface temperature on alpine mountainous cold regions, which is one of basic parameters of the regional hydrological and meteorological conditions, directly affects glacial recession, snow melt, distribution and freezing thawing process of permafrost, evapotranspiration, vegetation growth, and various underlying surface change process, and then changes the regional hydrological and ecological environment, becomes the important parameter of the research on land surface process and the study of eco-hydrological process. This paper tried to provide an overview of research on land surface temperature, and to introduce its influence factors and the ways to obtain land surface temperature data in high mountainous cold region. Relative to low elevation plain, the land surface temperature was significantly affected by local altitude, terrain and plant cover. There were some methods to obtain land surface temperature, such as measurement in situ, retrieval based on remote sensing and calculation by land surface process models, but there were some limitations while used on alpine mountainous cold regions. Land surface temperature data from meteorological stations were only about level bare ground, and the influence of terrain or vegetable cover was not considered. Therefore, the data could not represent the information of region scale on mountainous area. Land surface temperature retrieval from remote sensing data, because of calculation theory, ground observation verification and spatiotemporal resolution, made it difficult to fulfill research on hydrology, land surface process and eco-hydrological process in alpine mountainous area. Land surface process models estimated land surface temperature in the experimental sites with high accuracy, but reduced the accuracy while upscale to the region scale on the mountainous cold area, because of the error from input control meteorological, soil and plant variables, and the error of ground observation site verification. The future research on land surface temperature on alpine mountainous cold regions should strengthen field observations and improve data accuracy, to build a physical land surface temperature estimation method with topographic and vegetation parameters, and to contribute to research on land-atmosphere-water process in alpine mountainous regions. 相似文献