上地幔各向异性研究综述及在川滇地区的研究思路

简要介绍了地球介质各向异性研究的发展历程,重点介绍了国内外有关上地幔各向异性的研究工作及成果;阐述了上地幔各向异性的起源及其地球动力学意义;较详细地分析了上地幔各向异性研究的各种方法及其优缺点;论述了川滇地区各向异性研究的意义和目的,并提出了整个研究工作的内容和步骤.     

上地幔顶部折射波走时层析成像研究综述

简要介绍了上地幔顶部折射波走时层析成像研究的发展历程，详细介绍了上地幔项部折射波走时层析成像研究的各种方法并分析了其优缺点，介绍了国内外有关上地幔顶部折射波的研究工作和成果，阐述了上地幔顶部速度结构与构造活动的关系及其地球动力学意义。     

中国大陆及邻区上地幔各向异性研究

为了深化对中国大陆及邻区上地幔介质形变强度和方向的空间变化图象、各向异性和剪切波分裂、各向异性以及应变、应变和构造过程关系的认识，我们以剪切波在分层各向异性介质中的传播理论为指导，以分裂剪切波观测为基础，借助数字化地震资料和高分辨率的信号处理技术，给出了对136次地震的分析结果，得到了20个台站下面的上地幔各向异性介质的变形强度和方向的空间变化图象；并结合已有研究结果，对中国大陆及邻区上地幔各向异性特性及其起源问题进行了讨论．      

宁夏地区地壳上地幔各向异性研究

本文对国际、国内在地壳上地幔介质各向异性研究领域的发展历史及研究现状进行了简单回顾,交待了宁夏地区的构造环境,阐述了本文所采用的上地幔各向异性分析方法的原理,介绍了地壳各向异性产生的机理并选择了适当的分析方法,首次系统得到了较好的宁夏地区地壳上地幔各向异性测量参数,并进行了解释。     

上地幔各向异性的反演方法

详细推导了弱各向异性介质的地震波速，在此基础上介绍了用Pn震相研究上地幔各向异性的几种具体算法；推导了用SKS震相和ScS震相反学下地幔各向异性的方法、优缺点及几种方法的相互关系。     

玉树地区上地幔各向异性初步研究

上地幔各向异性的研究对了解地球各个圈层介质特性以及地球动力学的研究具有深刻意义,同时也有利于了解地壳和上地幔变形的一些特征,而剪切波分裂是研究地震各向异性的一种有效的手段和方法.     

震波层析显象法的地球物理基础

震波层析显象法是由医学界的 X 射线摄影诊断法发展而来的。本文对此法的地球物理基础作了综述,分为四个部分:①导言;②基本概念和具体解法,其中包括研究上地幔的面波分析、研究下地幔的体波分析和上地幔中波速的各向异性研究;③分布情形及其物理意义,包括上地幔的横向异质、下地幔的横向异质和上地幔的各向异性;④结语,其中指出,为地幔做震波层析显象,在地球物理上有极重大的意义,凡板块现象、热点、火山和地震的产生,地热和重力的分布,甚至地核、磁场的活动,都与地幔里物质对流的状况密切相关,利用地震资料的震波层析显象是极为有效的探索方法。     

用地震面波研究上地幔各向异性

本文论述了上地幔各向异性的参数描述和主要证据,以及与地球动力学的关系。并就近几年来国外利用地震面波研究上地幔各向异性的重要成果和主要方法作了综合评述。     

利用SKS波分裂研究上地幔各向异性及其在中国东部的应用

地震各向异性方法是研究地幔流动以及岩石圈变形最直接有效的方法之一,利用远震事件识别近乎垂直入射的SKS波震相能直接反映台站下方的上地幔各向异性。近年来,SKS波分裂由于识别方位各向异性灵敏、多解性小逐渐发展为探究大陆动力学及其演化以及地幔形变特征的有力工具。本文收集了近20年来利用SKS波分裂在中国东部地区开展的各向异性研究工作,综述了该方法在中国东部的研究进展以及存在的不足和有待解决之处;同时,还通过在长江中下游地区布设的102个高质量高密度的宽频流动台站以及中国国家数字地震区域台网262个固定台站的数据,详细分析了该地区的上地幔各向异性变形特征。     

中国大陆地壳与上地幔地震各向异性研究

地壳与上地幔各向异性研究在地球动力学领域有广泛的应用和重要的科学意义,其研究有助于许多地质和地球物理基本问题的解释.中国大陆的各向异性研究,在地壳与上地幔两个尺度上都有许多重要进展,并在基本理论和岩石实验研究中取得进步.文章认为,各向异性研究揭示的科学问题将会是广泛的和深远的.     

浙江省北部及邻区中强地震前地倾斜异常特征及其预测意义

解释并讨论了湖州和宁波台１９９３年以来的地倾斜资料,总结了震前有异常显示的６次地震。发现：①异常在现场记录资料中均有显示,异常形态的识别对预报地震有重要的意义;②能观测到异常全过程的倾斜仪与震中的距离基本符合式ｌｇＤｊ＝０．３０３（ＭＳ＋１．６）给出的监测能力半径,大于这个半径的台有时也能观测到异常,但多为短临异常。如果震前记录到异常的全过程,则利用单台资料可能对地震三要素进行预测。     

On the synchronism in the events within the core and on the surface of the earth: the changes in the organic world and in the polarity of the geomagnetic field in the phanerozoic

The data on geomagnetic reversals are compared with the changes in the organic world and with the lower-mantle plumes. The times of the formation of plumes and the times of their appearance on the Earth’s surface relate to the intervals characterized by the different frequencies of geomagnetic reversals, i.e., there is no interrelation between the formation of plumes and the frequency of the changes in the geomagnetic field polarity. At the same time, a certain synchronism is observed between the frequency of the geomagnetic reversals and the boundaries of the biostratigraphic ages, i.e., the changes in the organic world in the long-period range. A hypothesis is proposed, which explains the change in the sign of the geomagnetic field by the combined effect of the irregular rotation of the internal core relative to the mantle and the changes in the slope angle of the axis of the Earth’s rotation, which, in turn, results in synchronous events on the Earth’s surface: the rates of changes in the organic world.     

The differences in structure of the gravity field and the figure of the earth in the northern and southern hemispheres

Summary It was shown in [5] that the flattening of parallel sections of the geoid (ϕ=const.) differs in the northern and southern hemispheres. This leads up to the idea of studying further the size and shape of the Earth and the structure of the gravity field separately for the northern and for the southern hemispheres. In this paper attention is devoted especially to the mean values of the radius-vectors, to the best fitting ellipsoid parameters and to the mean values of gravity for the whole hemispheres, on the one hand, and for their ϕ=const. sections, on the other. The symbols used are the same as in [5,6]. Address: Politickych vězňů 12, Praha 1-Nové Město.     

Concentration and localization of hydroxylamine in the reservoirs and lakes in the territory of European Russia

Hydroxylamine concentration and localization in the Volga reservoir cascade and in the lakes of Yaroslavl province and Vladimir province were studied. It was found that, in microaerophilic zones of the most productive lakes, the rate of hydroxylamine formation is higher and its localization does not depend on the type of the limnological object (a reservoir or a lake), but is determined by the oxygen regime of the water body in question.     

ESW在磁尾磁场重联耗散区分形线附近的观测特性及其作用

磁场重联是空间能量释放和转换的重要机制.静电孤立波(ESW)虽然在空间中有广泛观测,但在磁场重联附近少有直接观测,对它在磁场重联附近的特性了解甚少.通过Geotail卫星对一个磁场重联事件的观测,仔细分析了其边界层上观测到的静电孤立波的特性,并讨论了它对磁场重联的影响.研究表明,亚暴期间在磁尾发生磁场重联,重联区域的分形线附近观测到了大量的静电孤立波,其特性与在其他地方观测到的并没有显著差别,但具有更明显的非线性和孤立性的特征.它们对电子加速和能量耗散有促进作用,加速磁场重联的进程.     

Distribution of lead and thallium in the matrix of the Allende meteorite and the extent of terrestrial lead contamination in chondrites

Selective chemical dissolution has been used to study the distribution of Pb and Tl in an ultrafine ?20-μm matrix separate of Allende. The matrix was exposed to high-purity reagents ranging from H₂O, then HCl of increasing concentration and finally HF-HCl mixtures. A total of 17 extractions were obtained, each for a minimum period of 10 days. The isotopic compositions of the Pb released during the slow dissolution of the matrix fall into four distinct groups. The first, consisting of four extractions, released a component of terrestrial Pb isotopic composition with a total abundance of about 1 ppb. The next six extractions, which contained the bulk of the indigenous Pb and Tl corresponding to 96% and 94%, respectively, of the total matrix abundance, was of a reasonably homogeneous Pb isotopic composition with mean ratios of²⁰⁶Pb²⁰⁴Pb= 10.00and²⁰⁷Pb²⁰⁴Pb= 10.74. In the final seven extractions, the released Pb falls into two higher isotopic groupings and probably results from the dissolution of debris from chondrules and inclusions. The apparent age of the internal matrix isochron is4562 ± 14 My. The release of Pb and Tl shows a reasonable correlation with the matrix dissolution. This indicates that the Pb and Tl reside predominantly within the matrix phases rather than as a localised phase. The Tl isotopic composition of two matrix fractions and whole meteorite were measured and found to be indistinguishable from the terrestrial²⁰⁵Tl/²⁰³Tl ratio. Measurement of a terrestrial reagent standard in the range 1–10 ng Tl gave, for 20 analyses, a mean²⁰⁵Tl/²⁰³Tl ratio of2.38907 ± 0.00102 (2σ).The estimate of terrestrial Pb contamination is considerably lower than the 6–300 ppb assumed in some recent studies in order to explain the phenomenon of apparent excess radiogenic Pb in chondrites. The problem of terrestrial Pb pollution and the evidence which argues against a relatively severe and homogeneous Pb contamination of meteorites, is briefly considered. The apparent initial isotopic composition of the bulk of the indigenous Pb in the Allende matrix was found to be²⁰⁶Pb²⁰⁴Pb= 9.57and²⁰⁷Pb²⁰⁴Pb= 10.47. This is of a higher composition than the Pb in the Can?on Diablo troilite phase and further indicates that the phenomenon of apparent excess radiogenic Pb in chondrites is real.     

Atmospheric ozone and the movement of the air in the stratosphere

Using over 2200 ozonesonde ascents, published byHering andBorden [1]–[5] and byDütsch et al. [6], [7], the average vertical distribution of the ozone mixing ratio is found for different latitudes and for different seasons up to a height of 30 km. The method by which the ozone formed at great heights in low latitudes becomes concentrated in the lower stratosphere of high latitudes is discussed, and the meridional circulation theory is strongly suggested.Oxford, May 1972.     

PCB and HCB in the sediments and waters of the Tiber estuary

The contamination by polychlorinated biphenyls (PCB) and hexachlorobenzene (HCB) in sea waters and sediments of Tiber River estuary has been studied in 1976 and 1977.PCBs have been detected in all the samples analysed at mean levels of 0.297 ppb (1976) and 0.135 ppb (1977); these levels are much higher than those proposed as acceptable for surface waters. Contamination increases with increasing distance from the shore.HCB has been identified in only 16% of the water samples analysed and it was found absent in sediment samples.The results are discussed relative to both the levels of PCB in other sea waters and the toxicity of these products to the aquatic animals.     

Regularities in the Space and Time Flow Variations in the Near-Mouth Reach and Delta of the Lena R.

Lena flow showed considerable, mostly climate-induced, changes in the recent 30–40 years. The character of these changes at the river watershed–sea border somewhat differs from that in the basin outlet station because of flow transformations in the near-mouth reach and, especially, in the delta. The new stationary and occasional expedition observations were used to improve the estimates of the major characteristics of the discharges of water, suspended sediment, and heat in the Lena outlet section and to identify the features and causes of their long-term and seasonal variations. Another important result is the estimation of flow characteristic in the reach downstream of the basin outlet station, at delta head, and on its coastline. New data are given on the present-day distribution of water and suspended sediment discharges between the major delta branches, their long-term variations, and the character of inundation of the near-head delta area during spring floods.