浙东与火山岩有关的非金属超大型矿床地球化学及同位素年代学研究   总被引：3，自引：0，他引：3  

任胜利  周新华 《矿物岩石地球化学通报》1997,(1)

浙东与火山岩有关的非金属超大型矿床地球化学及同位素年代学研究任胜利周新华（中国地质大学，北京１０００８３）（中国科学院地质研究所，北京１０００２９）收稿日期：１９９６－９－２３；修改稿：１９９６－１０－２２第一作者简介：任胜利男１９６５年生博士后地球...  相似文献   

超大型稀有稀土矿床的某些特征   总被引：2，自引：0，他引：2  

林德松 《矿产与地质》1997,11(1):14-19

稀有稀土超大型矿床的储量为大型矿床储量的５倍以上（ＲＥＥ、Ｂｅ）或１０倍以上（Ｌｉ、Ｃｓ、Ｎｂ、Ｔａ、Ｚｒ）。这类矿床大多与碱性岩类岩石有关，主要分布在地台区，成岩成矿时代以前寒武纪为主，其次为中生代。成矿作用具有多期次性，矿化往往发生在更为还原条件下。超大型富矿与深部成矿源有着直接联系  相似文献   

丽江大地震的中长期预报     

罗荣联 《地震研究》1997,20(1):9-12

本文简述对１９９６年２月３日丽江７．０级地震作出较成功中长期预报的历史事实。研究中采取着眼长期、关注群体、解剖个体、跟踪动态的基本思路，通过层层筛选、逐一排除、再行逼近的步骤，凭经验确定以丽江为中心的７级地震危险区，并提出防震减灾对策措施。云南省人民政府采纳了研究成果，批准省府办公厅于１９９５年３月８日发布地震中期预报，丽江地区行署为之做了防震准备，发挥了政府的减灾职能，取得较好的减灾实效。  相似文献   

大型板状交错层理内部沉积物的分异   总被引：2，自引：0，他引：2  

王泽中 《矿物岩石》1997,17(1):71-76

本文对取自长江上荆江三八滩大型板状交错层理内部同一细层不同部位的５个样品进行了粒度分析和矿物鉴定，结果表明，在同一细层内沉积物有明显的分异作用。细层中上部以中等粒径、低密度的颗粒为主，分选好。细层的下部和底部主要聚集沉积物的粗尾和细尾部分，因而分选较差。此外，密度较大的矿物亦趋于聚集在细层的底部。沉积物的这种分异主要是因为在沙波运移过程中矿物沿背流面发生重力分异且在背流面附近存在回流所致。大型板状交错层理内部沉积物的这种分异作用对认识其储集性能的层内非均质性有重要的意义  相似文献   

直眼掏槽的爆破作用及参数计算   总被引：4，自引：2，他引：4  

张奇  张玉明 《岩土力学》1997,18(2):51-56

论述了分阶分段直眼掏槽爆破机理，提出了分阶分段直跟掏槽爆破装药量的计算依据，并给出相应的计算方法。  相似文献   

Main Mineralization Mechanism of Magmatic Sulphide Deposits in China     

Tang Zhongli Gansu Bureau of Geology  Mineral Resource  Lanzhou  Gansu Fei Zhenbi 《《地质学报》英文版》1997,71(1):49-57

Before intruding, primary magmas have undergone liquation and partial crystallization atdepth; as a result the magmas are partitioned into barren magma, ore-bearing magma, ore-richmagma and ore magma, which then ascend and are injected into the present locations once ormultiple times, thus forming ore deposits. The above-mentioned mineralizing process is knownas deep-seated magmatic liquation-injection mineralization. The volume of the barren magma isgenerally much larger than those of the ore-bearing magma, ore-rich magma and ore magma. Inthe ascending process, most of the barren magma intrudes into different locations or outpoursonto the ground surface, forming intrusions or lava flows. The rest barren magma, ore-bearingmagma, ore-rich magma and ore magma may either multiple times inject into the same space inwhich rocks and ores are formed or separately inject into different spaces in which rocks and oresare formed. The intrusions containing such deep-seated magmatic liquation-injection depositshave a much smaller volume, greater ore potential and higher ore grade than that of in-situmagmatic liquation deposits. Consequently this mineralizing process results in the formation oflarge deposits in small intrusions.  相似文献   

ON THE BAROTROPIC INSTABILITY OF LARGE SCALE VORTICES^*     

Luo Zhexian 《Acta Meteorologica Sinica》1996,10(1):13-21

By using the linearized barotropic vorticity equation in polar coordinates the stability of perturbations on a large scale circular basic flow is transformed into a generalized eigenvalue problem,yielding the relationship between the growth rate of the amplitude of perturbations and the azimuthal wave number. Then, numerical experiments whose integration time is 60 model hours are performed in terms of a quasi-geostrophic barotropic model in Cartesian coordinates using the perturbation stream function field of unstable mode superimposed on a strong and weak circular basic flows as the initial fields. The experimental results reveal that the amplitudes of the initial perturbations in the model atmosphere grow with time. The amplitude of the perturbations superimposedon the strong circular basic flow grows quicker and forms a spiral-band-like structure.  相似文献   

长江下游感潮河段大洪水和特大洪水的形成及趋势   总被引：6，自引：0，他引：6       下载免费PDF全文

芮孝芳 《水科学进展》1996,7(3):221-225

分析了长江下游感潮河段大洪水和特大洪水高水位形成的水文因素,揭示了年最高水位今后一段时期内可能的变化趋势。主要结论是:该河段大洪水和特大洪水高水位的形成原因十分复杂,本世纪以来每次大洪水和特大洪水高水位的形成几乎都有其主要原因;该河段大洪水特大洪水高水位出现的频次有增加趋势;自1975年以来,年最高水位的均值呈明显的升高趋势,其主要原因是人类活动对防洪产生的负面影响,海平面上升也有一定的影响。  相似文献   

岩体节理形貌的分形维数与摩擦角的关系研究   总被引：1，自引：0，他引：1  

陈乃明 《岩土力学》1996,17(3):54-58

在土木工程设计和施工中，岩体节理的摩角是一个重要参数，该值的获取既费时又费力。本文首先简要介绍节理形貌的描述方法和分形几何理论，然后将分形理论引人岩体节理摩擦角的研究中，得出了用分形维数表示摩擦角的经验公式。关键词  相似文献   

ON THE BAROTROPIC INSTABILITY OF LARGE SCALE VORTICES          下载免费PDF全文

罗哲贤 《Acta Meteorologica Sinica》1996,(1)

By using the linearized barotropic vorticity equation in polar coordinates the stability of pertur-bations on a large scale circular basic flow is transformed into a generalized eigenvalue problem,yielding the relationship between the growth rate of the amplitude of perturbations and the az-imuthal wave number. Then, numerical experiments whose integration time is 60 model hours areperformed in terms of a quasi-geostrophic barotropic model in Cartesian coordinates using the per-turbation stream function field of unstable mode superimposed on a strong and weak circular basicflows as the initial fields. The experimental results reveal that the amplitudes of the initial pertur-bations in the model atmosphere grow with time. The amplitude of the perturbations superimposedon the strong circular basic flow grows quicker and forms a spiral-band-like structure.  相似文献