绿洲、沙漠及戈壁边界层特征对比分析   总被引：4，自引：0，他引：4  

朱平  蒋瑞宾 《气象》1996,22(3):48-50

利用黑河实验所取得的资料，对比分析了绿洲、沙漠及戈壁边界层中风、温、湿分布规律，从而为研究西北地区不同下垫面所造成的气候特点对生态环境的影响、土地的开发腹及人工改造自然环境等工作提供依据。  相似文献   

台风涡旋的结构及其与台风运动的关系     

李小凡 《热带气象学报》1996,12(4):314-323

用ＦＳＵ区域模式讨论台风涡旋结构及其与运动的关系，台风涡旋的运动在无基本环流和β平面条件下取决于轴不对称环流。而不对称环流的发展源自于从对称环流动能的转换。其率取决对称环流，不对称环流和地球涡度经向梯度三者的相互作用。由于不对称环流动能产生率随高度不变，故台风作为一个统一体以相同的移速移动。不对称环流的径向结构取决于对称环流的径向结构。  相似文献   

四川及邻区地壳垂直形变特征与地震的关系   总被引：6，自引：0，他引：6  

吕弋培  廖华 《四川地震》1996,(4):109-116

对四川及邻区五十年代至八十年代的精密水准复测资料进行处理，绘制了四川及邻区的地壳重直形变速率图、垂直形变速率梯度图和垂直形变速率梯度矢量分布图。结合研究区内构造特征，对上述图件进行分析。指出数处呈四象限分布的图像，结合地震活动进行解释，确定了研究区未来的地震危险区。  相似文献   

冀北东坪式金矿找矿远景区的岩石磁学研究     

郭友钊  李习安  董刚  梅新忠  董杰  李磊 《黄金地质》2001,7(2):29-34

通过区域成岩学与岩石磁学的融合，以东坪式大型金矿为例，根据岩石磁学的定量化数据，分析与东坪式金矿成矿有直接成因联系的矿性侵入岩、海西期岩体的磁化率、Q值异常，并以大型的东坪、金厂峪、峪耳崖金矿为已知条件，得到冀北地区东坪式大型金矿主要分布在矿性岩磁性梯度带的初步结论。  相似文献   

苏北高压变质带及其与北侧超高压变质带的关系   总被引：13，自引：1，他引：13       下载免费PDF全文

于津海  王赐银  林黎明 《地质学报》2001,75(1):82-90

在苏北超高压变质带以南存在一条与之平行的高压变质带。带内由东南向西北可进一步划分出蓝闪石-黑硬绿泥石带,石榴石-绿帘石带和蓝晶石-黄玉带三个变质亚带。从蓝门石-黑硬绿泥石带到蓝晶石-黄玉带变质温压逐渐升高,其峰期地热梯度为15±3℃/km,属于高压变质相系。北侧超高压变质带的典型矿物组合是石榴石+绿辉石+柯石英+金红石,地热梯度为9±2℃/km。高压变质带峰期变质与北侧超高压带峰期变质的地热梯度明显不同,而与超高压变质体的退变质地热梯度相吻合。结合同位素年代学资料,本文指出本区的高压变质作用与北侧的超高压变质作用不是同时发生,而是与超高压变质体的退变质作用同时发生于中生代的印支期。含柯石英榴辉岩的超高压峰期变质早于印支期,并经两次抬升出露于地表。  相似文献   

通过比降观测浅析三姓浅滩的水文特性     

续庆义  李振波  朱洪刚 《测绘与空间地理信息》2001,24(4):47-48

通过把比降测量的观测成果进行科学的分析 ,得出泥沙淤积的原因 ,并提出了有关的航道测量、整治工程的一些建议  相似文献   

应用流体包裹体研究内蒙古巴彦浩特盆地热演化史   总被引：7，自引：3，他引：7  

严永新  李亚玉  胡峻卿  林学庆  田云 《现代地质》2002,16(3):288-291

通过巴彦浩特盆地石炭系流体包裹体的研究认为 ,不同时代的样品尤其是中晚期包裹体的均一温度与埋藏深度之间存在良好的线性关系。有机质生烃在纵向上可以划分为未熟、低成熟、成熟及高成熟 4个阶段 ,时代上自侏罗系、下至奥陶系 ,跨度较大 ,却经历了相同的地热温度场。本区地温梯度较低 ,仅为 2 8～ 30℃ /km ,所有的升温热事件都发生在中侏罗世以后 ,主要勘探目的层石炭系烃源岩的成熟度处于液态窗阶段 ,有机质成熟、开始生烃的上限时间是侏罗纪以后 ,因此勘探目标应该以寻找晚期成藏为主  相似文献   

重力数据处理中几种断裂构造识别方法的组合应用     

郇恒飞  郭灿文  孙守亮  李永飞  高铁  王洋 《地质与资源》1992,29(5):467-475

  相似文献   

STUDY ON DYNAMIC RESPONSE AND INSTABILITY OF SOIL-ROCK MIXTURE DEPOSIT WITH DIFFERENT STONE CONTENTS AND SLOPE GRADIENTS          下载免费PDF全文

HAN Pei-feng  FAN Xiao-yi  TIAN Shu-jun  WEN Hua  ZHANG You-yi 《地震地质》1979,42(1):212-225

Soil-rock mixture deposit is an extremely heterogeneous loose rock-soil deposit formed since Quaternary, which is composed of blocks, fine-grained soil and pore with a certain engineering scale and high strength and has a certain stone content. These soil-rock mixtures accumulated on slopes have been completely destroyed and their mechanical strength is very low. They are widely distributed in the mountainous areas of Southwest China, which poses a great threat to the engineering. Earthquakes occur frequently in Southwest China, and the instability of soil-rock mixture deposit under seismic load is one of the important factors causing the damage to this type of deposit. The dynamic response of soil-rock mixture deposit under seismic load is an important index to study its instability mechanism under seismic load. Based on indoor shaking table model test, the influence of rock content and slope gradient on dynamic response characteristics of soil-rock mixture deposit was studied. In model tests, rock content is 30%, 40% and 50%respectively, and slope gradient varies from 20°, 30° and 40°. Two different seismic loading frequencies and three different excitation strengths were given. The peak acceleration(PGA)amplification coefficients in horizontal and vertical directions of soil-rock mixture deposit were analyzed under the change of rock content and slope gradient. The permanent displacement and deformation law of the top and foot of the slope of soil-rock mixture deposit were analyzed by model test. The experimental results show that the dynamic acceleration response characteristics of the soil-rock mixture deposits at the top and foot of the slope are different under different slope gradients and rock content conditions, and the horizontal PGA amplification coefficients of the soil-rock mixture deposits are also different. With the same seismic frequency and excitation intensity, the horizontal PGA amplification coefficient increases with increased slope gradient, and the rate gets faster. With the increase of stone content, the magnification coefficient of horizontal PGA decreases, and the higher the stone content, the slower the decrease rate of horizontal PGA magnification coefficient. When the slope gradient of soil-rock mixture deposit increases, the corresponding horizontal and vertical PGA amplification coefficients increase with the same seismic frequency and excitation intensity. The amplification coefficients of PGA in the vertical direction are different, but the overall magnification is weaker than that in the horizontal direction. The vertical PGA amplification coefficients of the foot, middle and lower parts of the slope are larger, while the vertical PGA amplification coefficients of the upper and middle parts of the slope tend to decrease. The higher the frequency of seismic wave is, the smaller the vertical PGA amplification coefficient corresponding to the same elevation will be, which indicates that the vertical PGA amplification coefficient is negatively correlated with the elevation. The variation trend of PGA magnification coefficient of soil-rock mixed deposit in vertical direction is different with the change of stone content. Under the same excitation intensity, the larger the slope gradient is, the larger the permanent displacement at the top of the slope will be, and the larger the rock content, the smaller the corresponding displacement at the top of the slope. The permanent displacement of the top of the slope is obviously larger than that of the foot of the slope, which indicates that the magnification effect of the top of the slope is obvious. After the vibration process and sliding of the landslide, the large-sized particles in the soil-rock mixture deposit move downward faster and slip on the surface of the deposit body. There was a very obvious phenomenon of particle sorting in the pile-up at the foot of the landslide body. The results of this study are of practical significance for the analysis of the dynamic response law of soil-rock mixture deposit under seismic load due to the change of rock content and slope gradient.  相似文献   

天山北坡雪岭云杉树轮宽度年表梯度特征分析     

喻树龙  李淑娟  姜盛夏  张同文  张瑞波  秦莉  尚华明  张合理 《沙漠与绿洲气象(新疆气象)》2020,14(2):1-9

在天山北坡不同区域间隔海拔高度100 m左右采集5个树轮梯度年表,分析树木径向生长沿海拔高度变化的规律。结果发现:在树轮年表特征中,平均轮宽、树龄和敏感度等存在海拔梯度变化,平均轮宽和敏感度随海拔升高而降低,而平均树龄则与海拔高度呈正相关。高海拔采样点在同一区域和不同区域间一致性最好,低海拔采样点次之,而森林中部最差,东部和中部低海拔区域采样点的一致性要好于西部,坡向、坡度等小生境的差异也是影响树轮生长垂直变化规律的重要因素。存在同时影响不同海拔高度树轮生长的环境要素,西部和中部高海拔树木对该要素的响应更显著,在更为干旱的天山北坡中部和东部,对树木径向生长的影响较大的环境因子要多于西部伊犁地区。  相似文献