层状大地频率域长导线源激发的电磁场

采用Fourier变换法从Maxwell方程组出发,导出了层状大地模型上接地长导线源激发的电磁场表达式。结果表明：接地长导线源实际上是2个接地电极和线电流源构成的一个组合源;其电磁场表达式表明平行于长导线方向的电场分量为2个接地电极激发的平行于长导线方向的电场分量和线电流激发的电场的叠加,垂直于长导线方向的电场分量和电场的垂直分量均是2个接地电极激发的;平行于长导线方向的磁场分量由2个接地电极所激发,而垂直于长导线方向的磁场分量为2个接地电极激发的垂直于长导线方向的磁场分量和线电流激发的磁场的叠加,磁场的垂直分量为线电流源所激发。进一步的结果分析表明,在均匀半空间上、大收发距时,2个接地电极激发的平行于长导线方向的电场分量和线电流激发的电场分量是相等的,2个接地电极激发的垂直于长导线方向的磁场分量和线电流激发的磁场分量是相等的,且它们的振幅与2个电极之间的距离成正比。     

Books

Book reviewed in this article
Response to 'A critique of the first volume of the Geological Conservation Review, by Douglas A. Bassett, formerly of the National Museum of Wales'
Sedimentary Petrology (2nd ed.) by M. E. Tucker.
The Processes of Fossilization by S. K. Donovan (ed.).
World Geomorphology by E. M. Bridges.
To Interpret the Earth: Ten Ways to be Wrong by Stanley A. Schumm.
Introduction to Physics of the Earth's Interior by Jean-Paul Poirier.
A Guide to the Geology and Land Forms of Central Australia by R. B. Thompson.
Field Experiments and Measurement Programs in Geomorphology by O. Slaymaker (ed.).     

Effects of iron black varnish on petrophysical properties of building sandstone

In zones washed by rain (façades, pinnacles, pilasters), fine siliceous sandstones are covered by a black varnish, which gives a dirty appearance to monuments. In composition, structure and areas covered by it, it differs from the usual black gypsum crust. Experiments carried out on blocks covered by black varnish show the modifications due to their growth. Results show that despite their low thickness and the coherence of the stone below, the accumulation of hydrophobic matters and the wetting-drying cycles modify the transfer properties of sandstones several centimeters below the surface. Thus, although sandstones seem to be protected by the black varnish, in the long run, a flake detachment process, in the areas covered by it, affects them. Therefore, damage to sandstones by black varnish can be explained by the fact that a wetting and drying cycle modifies the pore network.     

非饱和膨胀土边坡的稳定性分析

为了提高非饱和膨胀土边坡的稳定,采用了土工膜覆盖边坡表面的方法.基于非饱和渗流理论,采用有限元程序对用膜覆盖和不覆盖的边坡分别进行了降雨蒸发干湿循环条件下的数值分析.在计算结果基础上,采用极限平衡法分析了边坡的稳定性.结果表明,用膜覆盖后边坡能长期保持非饱和状态,土体吸力较高,其稳定安全系数明显高于无膜保护的边坡,用复合土工膜覆盖边坡有利于提高非饱和膨胀土边坡的稳定.     

Impacts of afforestation on groundwater resources and quality

Plans to double the proportion of land under forest cover in Ireland by the year 2035 have been initiated. The plan, primarily financially driven, ignores potential environmental impacts of forestry, particularly impacts on groundwater resources and quality. Since groundwater supplies almost 25% of Ireland's total potable water, these impacts are important. Field investigations indicate that afforestation leads to a reduction in runoff by as much as 20%, mainly due to interception of rainfall by forest canopies. Clearfelling has the opposite impact. Implications are that uncoordinated forestry practices can potentially exacerbate flooding. Groundwater recharge is affected by forestry, largely due to greater uptake of soil water by trees and to increased water-holding capacity of forest soils, arising from higher organic contents. Recharge rates under forests can be reduced to one tenth that under grass or heathland. Groundwater quality may be affected by enhanced acidification and nitrification under forests, due partly to scavenging of atmospheric pollutants by forest canopies, and partly to greater deposition of highly acid leaf litter. The slower recharge rates of groundwater under forests lead to significant delays in manifestation of deterioration in groundwater quality. Electronic Publication     

深水浊流沉积综述

深水浊积岩通常发育在风暴浪基面以下、几十米至数千米的水体深度范围内。当沉积中心位于或接近陆架边缘时,浊流沉积系统往往最为活跃,而且通常与相对海平面下降时期的低位体系域有关。深水沉积事件可细分为低位域早期和低位域晚期。低位域早期以规模不断增大和更频繁的流体（浊流）事件为特征;而低位域晚期则以规模逐渐变小且频率降低的流体（浊流）事件为特征。因此,在低位域早期,流体流量不断增大,水道以侵蚀并逐渐变深为主,仅能残存较少的沉积物。随后,在低位域晚期,流体流量逐渐变小,因而水道内的沉积填充物可以得以保存。浊流体系通常发育3个特征迥异的区域:区域1对应浊流体系的近端（上游）,以支流峡谷为特征;区域2为浊流体系的中间部分,以单一补给水道复合体系为特征,因浊流水体的高度比补给水道高,因而常常发育天然堤沉积;区域3为浊流体系的远端,以频繁的决口、砂质溢岸以及水道充填为特征,从地貌学上可以将其描述为末端扇,从沉积过程来看,可将其称为前缘分散体系。从层序地层学的角度来看,低位域沉积常常夹持于富泥的远端高位域和海侵体系域沉积之间。低位域早期—晚期沉积序列往往是以富砂的区域3末端扇沉积被区域2水道—天然堤沉积所覆盖为特征。     

Investigation of the Structure of Geological Process through Multivariate Statistical Analysis—The Creation of a Coal

The purpose of this study was to capture the structure of a geological process within a multivariate statistical framework by using geological data generated by that process and, where applicable, by associated processes. It is important to the practitioners of statistical analysis in geology to determine the degree to which the geological process can be captured and explained by multivariate analysis by using sample data (for example, chemical analyses) taken from the geological entity created by that process. The process chosen for study here is the creation of a coal deposit. In this study, the data are chemical analyses expressed in weight percentage and parts per million, and therefore are subject to the affects of the constant sum phenomenon. The data array is the chemical composition of the whole coal. This restriction on the data imposed by the constant sum phenomenon was removed by using the centered logratio (clr) transformation. The use of scatter plots and principal component biplots applied to the raw and centered logratio (clr) transformed data arrays affects the interpretation and comprehension of the geological process of coalification.     

用解析延拓求取剩余磁异常来圈定浅部隐伏磁铁矿脉

剩余磁异常求取是一种对磁场强度进行化极,解析延拓后提取浅部磁性介质异常的高通滤波方法。对于处于强磁性围岩的磁铁矿脉来说,浅部磁铁矿脉的异常往往被大规模的磁性围岩所引起的异常所掩盖。磁场强度与场源到测点距离的平方(二度体)或者立方(三度体)成反比,进行向上延拓的时候,由浅部场源引起的高频异常衰减快,深部场源引起的低频异常衰减的慢,因此地面实测磁场去掉向上解析延拓后的磁场值,可突出反映近地表磁性体引起的高频异常。这里通过解析延拓求取剩余异常,实现浅部磁铁矿脉异常信息的提取,为寻找隐伏的磁铁矿脉提供依据。并且利用此方法在秘鲁共和国Morritos铁矿圈定隐伏磁铁矿脉,验证了剩余异常在大规模的高磁性围岩中寻找隐伏磁铁矿脉的应用效果。     

Book reviews

Book Review in this article:
Introduction to Geomagnetism , by W. D. Parkinson.
Climatic Geomorphology , by Julius Büdel, translated by Lenore Fischer and Detlef Busche.
Contributions to Sedimentology of Some Carbonate and Clastic Units of the Coastal Dinarides. Excursion Guidebook , ed. by L. J. Babić and V. Jelaska
Continental Carbonate Sedimentation and Pedogenesis , by P. Freytet and J. C. Plaziat, edited by B. H. Purser
Rivers—Form and Process in Alluvial Channels , by Keith Richards
At the Sea's Edge: an introduction to coastal oceanography for the amateur naturalist , by William T. Fox, illustrated by Clare Walker Leslie.
Changing Sea-level Along the North Coast of Kuwait Bay , by Taiba A. Al-Asfour.
Carbonate Depositional Environments , ed. by P. A. Scholle, D. G. Bebout & C. H. Moore.
Dynamic Models in Earth-Science Instruction , by W. H. Yoxall.     

大牛地气田水平井通井卡钻处理

卡钻的处理方法主要有：通过施加外力如上提、下放钻具转动转盘使钻具恢复自由状态;通过调整钻井液性能、打稠塞、注酸、注解卡剂、反循环等方法使被卡钻具与井壁之间的填充物转移或者破坏;通过反丝钻具打捞甚至套铣起出被卡钻具。大牛地气田DPT-305水平井通井过程中发生一起严重的卡钻事故。通过重浆+清扫液、注酸、注解卡剂、环空憋压等方法处理被卡钻具与井壁之间的填充物;通过固定转盘上下活动来对被卡钻具施加扭矩;倒扣等方式处理这起卡钻事故,最终解卡。总结了事故的成因,分析了处理过程的得失,为以后处理此类事故积累了经验。     

Book Reviews

Books review in this article:
Sedimentary Environments and Facies, Ed. by H. G. Reading
A Color Illustrated Guide to Carbonate Rock Constituents, Textures, Cements, and Porosities, by Peter A. Scholle.
A Color Illustrated Guide to Constituents, Textures, Cements, and Porosities of Sandstones and Associated Rocks by Peter A. Scholle.
Cathodoluminescenceof Quartz and Its Application to Sandstone Petrology. Contributions to Sedimentology, No. 8, by U. Zinkernagel.     

逆冲推覆构造最新研究进展评述

逆冲推覆构造最新研究进展包括以下４个方面：１．创立新型逆冲推覆构造几何体系，其主要构造要素为台阶式逆冲断层，强调断裂与褶皱的相互关联性，可划分为断裂与褶皱两个分支系统。２．发展平衡构造剖面的研究方法，用于计算造山缩短量并检验构造解释。３．发现韧性推覆产生糜梭岩、混合岩、花岗岩三位一体的成岩作用和对金矿床的控制作用；清表推覆构造对油气藏的控制作用；浅表台阶式逆冲断层对金属矿藏的控制作用，这种控矿作用     

Book Reviews

Book reviewed in this article:
UPDATE: The Quaternary Ice Age (with particular reference to Britain) by Murray Gray.
Intermediate Statistics for Geographers and Earth Scientists by R.B.G. Williams.
Reservoir Sandstones by Robert R. Berg.
The Penguin Guide to the Landscape of England and Wales by P. Coones and J. Patten.
Perspectives on a Dynamic Earth by T. R. Paton.
An Excursion Guide to the Geology of the Isle of Skye by B.R. Bell and J.W. Harris.     

Crystallization of alkalic feldspar phenocrysts and origin of perthites in granitoids (as in certain intrusives in Northeast USSR)

Magmatic origin of large (up to 5 cm) phenocrysts of K-feldspar is indicated by mineralogical, chemical, and roentgenometric-structural analysis of the crystals. Perthites are found to be metasomatic products of replacement of plagioclase by K-feldspar. This reaction is accompanied by albitization of plagioclase and then by growth of albite after feldspar, in cleavage planes and elsewhere, or by spot-segregations of albite in places formerly occupied by plagioclase. — V.P. Sokoloff     

曲线翼型裂纹扩展路径理论分析及试验验证

采用数值和试验的方法对翼型裂纹的扩展路径进行分析,发现单轴下张开型裂纹的翼型裂纹的扩展路径逼近于过原主裂纹中心点、平行于最大主应力的一条直线。基于翼型裂纹路径这个特点,采用了双曲线参数方程近似表达真实翼型裂纹的扩展路径,通过翼型裂纹的起裂角、起裂点及翼型裂纹的渐近线方程求解了双曲线方程中的未知参数。采用双曲线翼型裂纹路径和试验中所得翼型裂纹路径进行了对比分析,二者吻合得很好,验证了采用双曲线近似表示真实存在的翼型裂纹模型的正确性。应用双曲线翼型裂纹模型对翼型裂纹的扩展和失稳进行分析,采用ABAQUS求解了双曲线翼型裂纹模型的应力强度因子,并与试验进行对比,发现双曲线翼型裂纹模型能很好地解释翼型裂纹的实际扩展规律,这表明了采用双曲线近似表示真实翼型裂纹路径的有效性。     

混积岩的分类和成因

对在混合作用的特征者了系统的阐述和讨论,混积岩是陆源碎屑和碳酸盐颗粒及灰泥混合在一起的沉积岩,属曲型陆源碎屑岩和碳酸盐岩之间的过渡类型,据其成分可分为４类,陆源碎屑和碳酸盐颗粒,灰泥的混合作用从成因上分为５种类型,副件突变沉积混合,相缘渐变沉积混合,原地沉积混合,侵蚀再沉积混合,岩溶穿插再沉积混合。     

锅穴一定是第四纪冰川的标志吗？ *

锅穴地貌现象在西方地学界已有长足的研究,在中国地貌学界也并不陌生。锅穴通常形成于山区溪流河床,也形成于风化风蚀、石灰岩溶蚀、湖滨海岸浪蚀等作用。北美、北欧末次冰期大冰盖覆盖过的地方有冰水形成的锅穴。因此,锅穴是一种多成因的地貌现象。见到锅穴而不加多方辨别论证,一概说成是冰川形成,显然是十分危险的。风化和溶蚀形成锅穴属于物理化学作用,而流水和浪蚀形成锅穴属于水动力作用。关于水动力如何形成锅穴,西方地学界早就形成了公认的解释。冰水锅穴经过反复研究也确认,其形成机理与山区河流无异,均属湍急流水在河床局部形成环流驱动沙砾长期磨蚀的结果。既非西方人19世纪提出的"Moulin Hypothesis"能够成功解释,更非眼下国内少数人倡导的"滴水穿石"能够说明。河谷跌水比想象的冰川终端冰崖缺水更加有利。     

考虑注浆压力的顶管施工引起土体变形计算方法

顶管施工引起周围地层变形的计算预测是顶管施工中必须加以重视的问题。地层的沉降变形与顶管施工的几个环节有密切的联系,如：①顶管姿态与开挖面土压;②顶进与换管;③注浆过程等。理论分析应考虑这几个施工中的关键因素。针对上述施工影响因素,提出了考虑注浆压力的顶管施工的地层移动的计算方法。用Mindlin的位移解分析模拟开挖面土压、顶进与换管过程中的侧面摩擦力的变化引起的位移;以Sagaseta的土体损失引起的土体位移模式分析姿态控制、土体损失等引起的变形;将圆孔扩张的Verruijt解拓展到三维,用于计算注浆压力引起的位移与变形。结果表明,考虑注浆压力的变化,可以得到更为合理的预测结果。     

Correction of matrix effects in the analysis of stream waters by flameless atomic absorption spectrophotometry

Direct injection techniques to measure trace metal concentrations by flameless atomic absorption were applied to fresh water samples of low to moderate matrix content. Many samples exhibited high non-atomic absorption which was decreased considerably by HNO₃ digestion within the furnace. The remaining background absorption could not be reduced by selective volatilization prior to atomization. It was taken into account where necessary by background measurements at nearby non-absorbable wavelengths.Other interference problems applying especially to Cd, Pb and Zn were eliminated by operating at higher than usual atomization temperatures. The method of standard additions to calibrate concentrations seemed to be adequate for these particular samples.Using the method recommended, precision tests to measure “within batch” and “between batch” variations were carried out for four elements in a typical sample.     

Influence of tectonics and neotectonics on the morphogenesis of the peak karst of Halong Bay,Vietnam

In northeast Vietnam, the karst of Halong Bay is characterized by very active neotectonics. The directional distribution of fracturing of the calcareous rocks is characterized by the influence of two major fault zones: the Red River fault zone (N140) and the Tan-Lu fault zone (N050). Karst development was favoured by intense fracturing, according to these two major directions, and reactived during recent tectonics by a compressional regime with σ1 N070, followed by an extensional regimes with σ1 near to EW that led to significant vertical movement. These tectonics, coupled with intense erosion, led to genesis and evolution of the spectacular morphology of this peak karst.