新疆北天山晚古生代蛇绿混杂岩带的变形研究     

崔可锐  施央申  洪建明 《新疆地质》1996,(1)

运用有限应变测量、磁组构和岩石组构等方法，对北天山存在着的一条晚古生代蛇绿混杂岩带进行了详细的构造变形研究。各种方法的研究结果互相吻合，与野外实际地质现象也相一致。混杂岩带属压扁变形，压缩量５１％，应变强度０．８３．３个主应变轴的平均产状分别是Ｘ＝１２６°∠４４°，Ｙ＝２５７°∠３３°，Ｚ＝８°∠２５°。文中最后讨论了该混杂岩带的形成机制、时代、运动学和动力学特征。  相似文献   

桂东南南渡—莲塘岩体的应变测量与应变特征     

冯佐海  梁金城 《大地构造与成矿学》1996,20(2):172-183

桂东南南渡—莲塘岩体及其围岩的应变测量结果表明：岩体总体以压扁变形为主，收缩变形为辅；热接触变质带内近岩体—侧以压扁变形为主，而远离岩体则转为以收缩变形为主。花岗岩浆沿博白—岑溪断裂带内由左旋走滑剪切所产生的构造位张空间侵位，故岩体和围岩的应变强度均软弱。  相似文献   

用数值模拟方法研究第四纪古气候──以LLN二维模式为例   总被引：1，自引：0，他引：1       下载免费PDF全文

李雪松 《第四纪研究》1996,16(4):289-299

本文着重介绍LLN模式对中晚第四纪大陆冰量变迁的模拟研究。由于天文学研究已经推算出大气层顶部太阳辐射过去和将来的长期变化，因而对本文的LLN二维模式而言，能否有效地进行古气候模拟在很大程度上取决于对古CO₂浓度的重建。随着对第四纪CO₂历史研究的不断深入，LLN模式对古气候长期变迁的模拟已从最初的末次冰期－间冰期延伸到0.6Ma B.P..。模拟的大陆冰量变化与地质记录对比良好，二者在与地球轨道要素有关的天文频率上的波动具有很高的相关性。  相似文献   

中国的特种精密工程测量   总被引：2，自引：1，他引：2  

吴翼麟 《测绘工程》1997,6(2):1-7

介绍大坝变形观测、波带板激光准直系统等特种精密工程测量方法，在工程与工业建设、大型建构筑物变形观测及抗灾减灾等方面取得的成就和效益；阐述特种精密工程测量的成长道路，以及当前特种精密工程测量的热门话题与发展趋势。  相似文献   

Case 21 water level and strain changes preceding and following the August 4, 1985 Kettleman Hills, California, earthquake     

Evelyn Roeloffs  Eddie Quilty  C. H. Scholtz 《Pure and Applied Geophysics》1997,149(1):21-60

Two of the four wells monitored near Parkfield, California, during 1985 showed water level rises beginning three days before theM _w 6.1 Kettleman Hills earthquake. In one of these wells, the 3.0 cm rise was nearly unique in five years of water level data. However, in the other well, which showed a 3.8 cm rise, many other changes of comparable size have been observed. Both wells that did not display pre-earthquake rises tap partially confined aquifers that cannot sustain pressure changes due to tectonic strain having periods longer than several days. We evaluate the effect of partial aquifer confinement on the ability of these four wells to display water level changes in response to aquifer strain. Although the vertical hydraulic diffusivities cannot be determined uniquely, we can find a value of diffusivity for each site that is consistent with the site's tidal and barometric responses as well as with the rate of partial recovery of the coseismic water level drops. Furthermore, the diffusivity for one well is high enough to explain why the preseismic rise could not have been detected there. For the fourth well, the diffusivity is high enough to have reduced the size of the preseismic signal as much as 50%, although it should still have been detectable. Imperfect confinement cannot explain the persistent water level changes in the two partially confined aquifers, but it does show that they were not due to volume strain. The pre-earthquake water level rises may have been precursors to the Kettleman Hills earthquake. If so, they probably were not caused by accelerating slip over the part of the fault plane that ruptured in that earthquake because they are of opposite sign to the observed coseismic water level drops.  相似文献   

Migmatite structures in the Central Gneiss Complex, Boca de Quadra, Alaska   总被引：3，自引：0，他引：3  

E.L. McLELLAN 《Journal of Metamorphic Geology》1988,6(4):517-542

Abstract Migmatite structures in the Coast Plutonic-Metamorphic Complex are well exposed in the inlet of Boca de Quadra, southeast Alaska. Two types of anatectic migmatites are present. Patch migmatites formed by in situ melting and subsequent crystallization of melt. Diktyonitic migmatites comprise a discontinuous veined network of leucocratic material, in which leucosomes enclose boudins of host rock. The margins of these boudins show the development of both melanosomes and shear band fabrics.
Strain analysis of diktyonitic melanosomes indicates that these regions have undergone volume decreases of 20-27%. This volume decrease is attributed to melt extraction into the adjacent fracture-filling leucosomes. Thus, diktyonitic migmatites formed by shear-induced segregation of partial melt, whereas in patch migmatites the lack of shear stresses inhibited melt segregation. The variable structural style of anatectic migmatites in Boca de Quadra is not related to host-rock composition, but may be due to differences in the amount of differential stress during migmatization. These in turn may be controlled by host-rock strength and/or diachroneity of migmatization and deformation.
Determination of volume changes during migmatization using strain analysis is potentially capable of discriminating intrusive and anatectic migmatites and consequently of documenting melt segregation and subsequent migration across crustal levels.  相似文献   

用SPOT卫星影像研究阿木尔林业局森林火灾损失     

赵宪文  李继泉 《遥感学报》1989,(2)

本研究以1987年5月30日接收的法国SPOT卫星标准假彩色合成影像为主要信息源,对大兴安岭阿木尔林业局火灾造成的林地损失进行了研究。文中着重介绍了面积量算方法、原理和误差;选取适量地面样地,用抽样统计和角规辅助目测方法计算蓄积损失并与二类调查结果进行比较;在影像上按火烧等级的判读结果、现地景观与烧死率─火灾的定量描述,及三者之间的一致性。结果表明,应用SPOT卫星资料,按本研究所介绍的方法进行火灾损失估计,可快速、经济地获得所需结果,并可满足精度要求。  相似文献   

低频数字电磁测深仪器系统及其在攀-西地区的应用          下载免费PDF全文

刘士杰  卢军 《地球物理学报》1989,32(4):417-422

本文介绍了在CTM-302型三分量磁通门磁力仪的基础上,研制的低频数字化大地电磁测深仪器系统;并根据该系统的功能和在攀-西地区的应用情况,对其发展前景进行了探索。  相似文献   

Rates and patterns of bedrock denudation by coastal salt spray weathering: A seven-year record     

D. N. Mottershead 《地球表面变化过程与地形》1989,14(5):383-398

Rapid surface lowering of bedrock is taking place in the supratidal zone by salt spray weathering. A seven-year run of data demonstrates a mean rate of lowering of 0·625 mm a^?1. Considerable variation exists in annual point lowering values within measurement sites, although between-site variation is not significant. Aggregate year to year variations in surface lowering are not significant. Spatial variation in individual point values may be compensated by temporal variation over an 11-year period. There is a marked summer maximum in surface lowering rate, and this is strongly correlated with monthly air temperature. Spatially and temporally episodic swelling of the rock surface is demonstrated. This does not correlate statistically with any available climatic variable and is deemed to be a real and largely stochastic phenomenon. It is interpreted as rock bursting at the granular scale due to haloclasty. The processes most likely to be responsible for the observed rapid denudation are crystallization and thermal expansion of halite, both of which are enhanced by high summer temperatures.  相似文献   

试论小型梭车的设计     

李祖光 《地球科学》1985,(3)

根据地质勘探小断面巷道的特点,结合对YS—25梭式矿车的研究,论文提出了小型梭车的主要参数——容积的计算式,并进行了生产验证。论文指出车型设计应以提高容积系数为主,注重车箱断面的合理宽高比,以获得最佳的装载效率。至于安装功率的选取,笔者认为应充分考虑梭车纯运转时间短的工作特点,不必按尖峰载荷值计算,可直接按实需牵引力加以确定。  相似文献