PROCEEDINGS OF THE EIGHTH GENERAL MEETING HELD IN PEKING,JULY 25th. & 26th.,1924.     

W.H.WONG 《地质学报》1924,(Z1)

The eighth general meeting of the Geological Society of China was the first meeting in the year 1924, following the Annual Meeting. It was arranged in two evenings as follows.  相似文献   

Anhydrous Phase Equilibria in Earth's Upper Mantle     

SAXENA  S. K.; ERIKSSON    G. 《Journal of Petrology》1985,26(2):378-390

Phase equilibrium relations are computed in five different chemicalcompositions appropriate for a primitive upper mantle (estimated),a peridotite, an olivine-basalt, an olivine-tholeiite, and aquartz-tholeiite in the pressure range of 1 bar to 100 kb andin the temperature range of 500 to 1500 ?C. The mineralogicalphase assemblages change from peridotite and lherzolite to garnetgranulites, eclogites and kyanite-quartz-eclogites. The smallpressure-temperature field of stability of plagioclase-garnet-granulitein the primitive compositions extends at 600 ?C from less than3 kb to more than 15 kb in the quartz-tholeiite compositionwith intermediate pressure values in other basalts. Continentalcrust with composition similar to quartz-tholeiite remains asplagioclase-garnet-granulite changing to eclogite only belowa depth of 50 km. Calculated adiabats in the peridotite compositions show thatdiapirs must ascend from a depth of at least 300 km to becomepartially molten in the low-velocity zone. Various shallowerdepths of partial melting are possible for material ascendingfrom depths corresponding to the oceanic geothermal gradient. Actual pressure-temperature densities of rocks have been calculatedfrom the mineral densities computed for the equilibrium assemblageson the oceanic geothermal gradient. While there are no importantchanges found in the peridotite density down to a pressure of100 kb, there are important inflections in the pressure-densitycurve in quartz-tholeiite which relate to the increasing conversionof plagjoclase to jadeite component in clinopyroxene and a sharprise in density due to the quartz-coesite phase transformation.  相似文献   

中国大地构造基本特征及其发展的初步探讨   总被引：5，自引：0，他引：5       下载免费PDF全文

TECTONIC MAP COMPILING GROUP  INSTITUTE OF GEOLOGY  ACADEMIA SINICA 《地质科学》1974,9(1):1-17

大地构造是地壳形变的结果,而地壳形变是在地壳形成的基础上发展起来的。地壳的形成主要表现为地质体的建造过程,包括地壳形成的地质时期中,不同温度和压力下所产生的沉积岩、岩浆岩和变质岩的类型、组合和相带的发展。地壳的形变主要表现为地质体的改造过程,包括各种岩层在形成过程之中或以后,经受内力和外力作用而产生的各种微观和宏观的结构变化,如流动、褶曲、破碎和断裂等。  相似文献   

地震的感应磁效应（一）——三维电磁感应的数值理论          下载免费PDF全文

中国科学院地球物理研究所第十研究室第二组 《地球物理学报》1977,20(1):70-80

地震的感应磁效应包括两部分:（一）三维电磁感应的数值理论;（二）地震感应磁效应的模拟计算。本文是其中的第一部分,从Maxwell方程推得的扩散方程出发,给出了一般三维电磁感应的基本方程、边界条件和求解方法,建立了完整的三维电磁感应的数值理论。计算结果将另文讨论。  相似文献   

地学发展若干问题及对策     

GEOSCIENCE DIVISION OF CHINESE ACADEMY 《地球科学进展》1991,6(3):1-25

一、目的 地学包括地质学、地理学、地球物理学、地球化学、大气科学、海洋科学,以及环境科学、空间科学、生态学和资源问题的一部分,其中大部分是自然科学中最早形成的一些学科,有着悠久的发展历史;而另有一些则是由于当代技术发展和人类面临要解决的重大问题的需要而应运产生的新学科。所有这些学科和它们的若干分支在当代都有着蓬勃的发展,起着越来越大的作用。  相似文献   

一九九一年国家自然科学基金资助地质学项目表          下载免费PDF全文

国家自然科学基金委员会地球科学部 《地质科学》1992,(2):198-211

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COMPUTER-GENERATED MULTICOMPONENT CALIBRATION DESIGNS FOR OPTIMAL ANALYSIS SAMPLE PREDICTIONS     

KIMBERLY HITCHCOCK  JOHN H.KALIVAS  JON M.SUTTER 《地理学报(英文版)》1992,(2)

This paper utilizes variable step size generalized simulated annealing(VSGSA)to design multicomponentcalibration samples for spectroscopic data.VSGSA is an optimization procedure which is capable ofconverging to exact positions of global optima located on multidimensional continuous functions.On thebasis of analysis sample response vectors,optimally designed calibration concentration matrices areobtained assuming knowledge of components present.The complexity of response surfaces establishedby the optimization criteria is described.  相似文献   

Airline networks and the international diffusion of severe acute respiratory syndrome (SARS)   总被引：2，自引：0，他引：2  

JOHN T BOWEN JR    CHRISTIAN LAROE† 《The Geographical journal》2006,172(2):130-144

In fewer than four months in 2003, severe acute respiratory syndrome (SARS) spread from China to 25 countries and Taiwan, becoming the first new, easily transmissible infectious disease of the twenty-first century. The role of air transport in the diffusion of the disease became obvious early in the crisis; to assess that role more carefully, this study relates the spatial-temporal pattern of the SARS outbreak to a measure of airline network accessibility. Specifically, the accessibility from those countries that were infected by SARS, beginning with China, to other countries was measured using airline schedules. The country-pair accessibility measure, along with other country-level factors relevant to the disease, were tested as determinants of the speed with which SARS arrived in infected countries as well as its failure to arrive in most countries. The analyses indicate that airline network accessibility was an especially influential variable but also that the importance of this variable diminished in the latter weeks of the outbreak. The latter finding is partly attributable to public health measures, particularly health screening in airports. The timing and geography of those measures are reviewed using data from media reports and interim World Health Organization (WHO) documents during the outbreak. The uneven effort to curtail the international diffusion of SARS suggests further planning is needed to develop a concerted response to contain future epidemics.  相似文献   

Aspects of the Weichselian chronology in central East Greenland     

SVEND FUNDER  CHRISTIAN HJORT 《Boreas: An International Journal of Quaternary Research》1973,2(2):69-84

From central East Greenland, C₁₄ ages between 19,500 > 40,000 years B.P. have been obtained for six samples of marine bivalve shells. The ages seem to be consistent with geological observations and form the basis for a tentative chronology for the Weichselian ice age in the region. It appears that the maximum glaciation during Weichselian times was attained more than 40,000 years ago, and that since then ice-free areas have existed. This assumption agrees with evidence of botanical refugia in the region, and the restricted glacier activity especially during the Upper Pleniglacial (ca. 30,000–15,000 years B.P.) is explained by a reduced supply of moisture. A comparison with evidence from other parts of Greenland indicates that different glacial histories can be expected for different sectors of the Greenland Inland Ice.  相似文献   

我国西北地区地壳中的高速夹层   总被引：13，自引：1，他引：13       下载免费PDF全文

曾融生  滕吉文  阚荣举  张家茹 《地球物理学报》1965,14(2):94-106

在我国西北地区的柴达木盆地东部和甘肃地区,在距离炮点40互100公里处,能够接收到不少能量较强的地壳深界面反射波。另外还发现一种与一般反射波性质不同的波,其视速度特大,视速度随距离的变化不大,而且有较明显的终点;其吋距曲线与一般深界面反射波的时距曲线相交。根据它的特征可以判断地壳中存在具有速度梯度的高速夹层.求得的夹层参数为: 甘肃地区柴达木盆地东部覆盖层厚度 18.8公里 30.5公里覆盖层平均速度 5.5公里/秒 5.3公里/秒夹层厚度 6.0公里 3.2公里夹层速度 7.5-8.5公里/秒 7.5-8.0公里/秒夹层的上下界面均为强反射面,可以产生多次反射波。分別利用相邻两个反射波可以求得各层参数,并能避免射线折射的影响。甘肃地区和柴达木盆地东部的地壳厚度分別为51和52公里。地壳中有高速夹层的存在,可以更好地说明P~*速度分散的原因,而且也能够解释Lg波的传播机制。  相似文献