Properties of wave velocity for two types of granitoids at high pressure and temperature and their geological meaning

The wave velocity for two types of granitoids was measured using the analytic method of full-wave vibration at high pressure and high temperature. The laws of velocity changes for them differ with the pressure boost and temperature rise, and the velocity change of S-type is more violent than that of I-type. The “softening point” of compressional wave velocity (V μ) is also revealed during the measurement for two types of granitoids imitating the pressure and temperature at a certain depth. But the depth of “softening”, V_p after “softening” and the percentage of V_p’s drop around the “sofrening point” for two types of granitoids are obviously different. The depth of “softening” is 15 km approximately and V_p after “softening” is 5.62 km/s for S-type granitoid. But for I-type granitoid the depth of “softening” is 26 km approximately and V_p after “softening” is 6. 08 km/s. Through careful analysis of rock slices after the experiment, it was found that the “softening” of elastic-wave velocity is caused by the partial melting of granite. Combined with the results of geophysical prospecting, these results suggest that the low-velocity layers developing in the interior of Earth crust are related to thc partial melting of different types of granitoids. The formation of the low-velocity layer in the upper-middle Earth crust is closely related to the development of S-type granitoid, but that in the lower Earth crust is closely related to the development of I-type granitoid.     

计算机多媒体技术在地学领域中的某些应用

结合地质工作特点，概述了计算机多媒体技术在地质科研、地质教育、成果汇报演示以及地质信息管理方面的应用成果，展示了多媒体技术在地学领域中的应用前景。     

东风山前寒武纪含铁建造金矿床中的稀土元素

东风山含铁建造金矿床中稀土元素含量普遍较低。东风山群是含矿层,其不同层位岩石和矿物的稀土含量有所差别。大理岩和含铁层中铁闪石的稀土含量最低,甚至低于稀土地壳丰度;上部角岩、下部角岩和石榴子石中稀土含量近似其他壳丰度;而板岩和花岗岩中稀土含量远高于其他壳丰度。稀土元素分布的特点反映了东风山金矿床形成于一个半封闭和较还原的海盆地,金矿化是在弱碱性条件下产生。黄铁矿中出现独居石类矿物,这可能与陆壳重熔改造形成花岗岩时产生的局部富轻稀土热液沿黄铁矿裂隙渗入有关。     

生态系统地震灾害初步研究

研究地震灾害的目的是为了保护人类.人类与周围的环境组成一个密不可分的系统,这个系统即生态系统.截止目前地震灾害的研究还局限在直观的人员伤亡和建筑物破坏,尚未涉及地震对生态系统的灾害影响,从而也未注意地震给人类带来的间接、众多、较长期的灾害影响.要真正保护人类免受地震灾害,就需要研究认识生态系统地震灾害.以人类为核心,按照构成生态系统的主体和环境因子的不同,可将生态系统由内向外、逐层包容地划分成社会生态系统、环境生态系统和自然生态系统三个层次类型.     

吉林-日本区深震特征及板块俯冲图像分析

根据USCS地震资料：分析了吉林-日本深震区地震的深度特征．结果表明：吉林-日本深震区地震位于太平洋板块与欧亚大陆板块的交界带上．其北支地震活动强于南支．同时也揭示了该区地震深度、地震频次以及地震能量之间的关系．指出其最容易发生强震的地震层位在570-580km左右。由深度资料推断板块间的作用方式，太平洋板块向欧亚大陆的挤压是一个由浅入深的过程，在不同的部位其俯冲角度与俯冲距离是不一样的，一般来说，倾角越大，俯冲越陡．水平延伸距离越短；反之，倾角越小．俯冲越平缓，水平延伸距离越长。     

双肢短肢剪力墙结构抗震性能试验研究

根据六片双肢短肢剪力墙结构试件低周反复荷载试验，量测了试件在荷载作用下的变形和钢筋的应变。根据截面内钢筋应变值采用直线和曲线两种方法拟合了截面内的应变变化情况。据此计算出各试件墙肢截面内钢筋和混凝土的应力和截面内力大小，以及各试件墙肢内的局部弯矩和整体弯矩大小。分析了内力的变化规律，并对不同肢厚比大小的短肢墙结构进行了定量评价。     

利用GPS资料浅析华北地区块体运动及与地震活动的关系

为了研究华北地区近年地壳水平运动的状态与演化．利用10a来华北地区网络工程、山西断裂带GPS观测成果．结合该区地质构造背景．分析了华北地区各块体运动的方向、速率变化及其与区内所发生地震的关系．初步得出以下结论：在区域应力场相对稳定时，表现为区域内GPS观测点整体趋势性运动不明显；而在区域应力场相对变化时．表现为影响区域内GPS观测点出现明显的整体趋势性运动。     

山区三维地震勘探大时差静校正及时深转换

山地煤矿采区地形条件复杂，正确进行大时差静校正是处理好二维地震勘探资料的重要一环。大时差静校正会改变煤层反射波时间(t0)及双曲线特征，为减小校正误差，需设立一个CMP面，将校正量分为高频分量和CMP校正量。在地形高差变化剧烈的山地，不能用高于地表面的统一基准面为零线进行时深转换，须进行充填层时差(△t)校正，将统一基准面校正到地表面，再以地表面为零线进行时深转换成图。以便准确无误的展示煤层赋存形态，提高构造图精度。     

Age of Yingfeng rapakivi granite pluton on the north flank of Qaidam and its geological significance

Rapakivi granite is a very rare and special type of rocks in the crust. Nearly all the typical Proterozoic rapakivi occurred in stable craton, and was regarded as representing special anorogenic settings and rifting events of the supercontinents. Therefore, rapakivi has constantly been attracting the attention of researchers from various countries[15]. For example, the Protero- zoic rapakivi granites occurring in Miyun, Beijing, has been studied in detail by the researchers both at home and …