龙首山芨岭复式岩体Sr-Nd-Pb同位素特征及意义

<正>0引言龙首山多金属成矿带是我国内陆极具特色的成矿带之一,成矿带东段产有世界著名的与超基性岩有关的Cu-Ni-PGE硫化物矿床(金川铜镍硫化物矿田),中段产有我国典型碱交代型铀矿床(芨岭、新水井矿床等),西段则发育有我国乃至世界少有的伟晶状白岗岩型铀矿床(红石泉矿床)。龙首山碱交代型铀矿化主要与加里东期芨岭花岗岩关系密切,本次研究在前人工作基础上,对芨岭岩体开展系统Sr-Nd-Pb同位素     

红石泉铀矿床含矿伟晶状白岗岩成岩特征及其地质意义

红石泉铀矿床位于华北地台西部边缘、阿拉善台隆南缘北西西向龙首山拱断带的西段,矿体产于侵入到下元古界龙首山群中的伟晶状白岗岩体中(图1)。该矿床是我国近年来发现的一种新型铀矿床,类似于纳米比亚的罗辛矿床。所不同的是,红石泉铀矿床属于吕梁期岩浆气成热液成矿作用和华力西期含矿热液成矿作用复成因矿床。该矿床的形成与伟晶状自岗岩的关系十分密切,因此探讨伟晶状白岗岩的地质特征、演化特点、成岩物理化学条件、     

甘肃红石泉铀矿床含矿主岩Sr-Nd-Pb同位素特征及意义

<正>甘肃红石泉铀矿床属于龙首山多金属成矿带一部分,其含矿主岩为元古代伟晶状白岗岩,前人在岩石学、地球化学等方面有一定的研究(王木清等,1982;张诚等,1989;辛存林等,2013),但是对于与岩浆物质来源及构造属性密切关联的Sr-Nd-Pb同位素特征研究较少。本文选择该矿床主要含矿主岩—伟晶状白岗岩体开展Sr-Nd-Pb同位素相关研究,总结其特征,在此基础上探讨其岩浆物质来源及与铀成矿之间的关     

甘肃红石泉伟晶岩型铀矿床地质、地球化学特征及成因探讨

红石泉矿床位于龙首山铀成矿带的西段,是我国发现的最为典型的伟晶岩型铀矿床,具有岩体型矿化的特点,铀矿化发育于伟晶岩体内部和接触混染带内。通过对含矿主岩伟晶岩进行系统研究表明,红石泉矿床中铀以晶质铀矿、沥青铀矿和铀黑形式存在。在中条造山运动晚期(1 735±67) Ma形成初始铀矿化,并在海西期(356±46) Ma部分矿石发生了热液叠加改造。早期岩浆成矿阶段主要形成晶质铀矿,晚期热液叠加改造阶段主要形成沥青铀矿,并发育了与芨岭钠交代型铀矿床相似的“四位一体”蚀变组合,热液改造过程是一个去K、增Na的过程。     

革命沟矿床蚀变分带及元素地球化学特征?

正革命沟铀矿床位于龙首山成矿带中东段,由原西北地勘局182大队于1966年首次发现,近半个世纪以来,前人对该矿床的地质特征和铀矿化特征做了大量研究,取得了丰富的成果~(??)。本文在分析和综合前人对硅质脉型铀矿床地质特征研究的基础上,结合最新勘查成果,对革命沟矿床的蚀变分带和元素地球化学特征做了研究。1矿床地质与矿体地质革命沟矿床位于芨岭花岗岩体北部革命沟断裂东段,是由中元古界墩子沟群大理岩构成的一个     

基于质量平衡计算对甘肃龙首山红石泉铀矿热液蚀变成矿作用的研究

红石泉矿床是甘肃省龙首山地区重要的铀矿床,但以往的研究对红石泉地区热液蚀变研究往往局限于定性分析,为了定量确定其对铀成矿作用的影响,本次研究首次引入质量平衡算法,通过对红石泉地区新鲜伟晶状花岗岩与蚀变伟晶状花岗岩的对比分析,在本地区热液蚀变对铀矿床的形成起到的作用进行了定量研究。研究表明,红石泉矿床铀成矿经历了至少二次成矿作用,其中部分矿段热液蚀变迁入的U元素达到原生的36倍以上,说明热液蚀变对铀成矿起到了至关重要的作用;同时从机理上阐述了热液蚀变产生的赤铁矿化等蚀变可以作为找矿指示标志的原因。     

龙首山成矿带铀成矿规律及其与地质构造运动、地壳演化关系探讨

甘肃省龙首山成矿带是我国西北地区一条重要的铀-多金属成矿带,属祁连-秦岭铀矿省的一部分。文章阐述了龙首山成矿带含铀建造、岩浆作用、构造特征,对区域铀成矿基本规律和矿床特征进行分析,并深入探讨了构造运动以及地壳演化过程与铀成矿的关系。综合研究认为:前寒武纪阿拉善台隆的形成,为成矿奠定了物质基础,属于成矿元素预富集期;古生代祁连裂谷作用下,龙首山拱断带的形成及花岗岩的演化,对龙首山成矿带的形成具有重要作用;中新生代区域地质运动表现为断块活动阶段,对铀矿床的影响起改造、再富集作用。根据研究成果,指出了下一步找矿远景区。     

红石泉铀矿床晶质铀矿矿物学特征研究及其找矿意义

龙首山铀成矿带西段的红石泉铀矿床是中国典型的伟晶岩型铀矿床,具有“岩体型”矿化特征。文章以红石泉晶质铀矿为切入点,结合全岩地球化学与晶质铀矿矿物学以及元素地球化学特征,探讨红石泉矿床铀矿物蚀变演化及铀矿化特征,得出以下认识：(1)红石泉矿床原生晶质铀矿受明显热液蚀变改造,w(UO₂+ThO₂+PbO+REE₂O₃+Y₂O₃)逐渐减少,w(CaO+SiO₂+FeO+Al₂O₃)明显增加,在蚀变改造过程中U从晶质铀矿中释放,随流体迁移;(2)红石泉矿床晶质铀矿Pb丢失现象较普遍,其中在背散射图像中较亮的A类晶质铀矿Pb丢失机制为重结晶,其重结晶加权平均年龄为(416±18)Ma,而较暗的B类晶质铀矿Pb丢失机制为扩散(浸出);(3)红石泉矿床岩浆铀成矿阶段之后,存在后期热液铀成矿作用。根据全岩元素地球化学特征,结合区内正长岩结晶年龄,文章推测红石泉矿床热液铀成矿与正长岩浆分异的碱性热液关系密切。     

红石泉矿床含矿主岩及矿化特征

红石泉铀矿床是我国近年来发现的新类型,它与纳米比亚白岗伟晶岩型铀矿床相比有某些类似的特点。我们对该矿床产出的地质环境、含矿主岩特征、矿化富集因素以及成矿时代进行了研究,并对含矿主岩和矿床成因有些新的看法和认识。     

甘肃红石泉铀矿床黑云母特征及意义

<正>甘肃红石泉伟晶状白岗岩型铀矿床是我国最为典型的白岗岩型铀矿床,也是迄今我国发现的最古老铀矿床之一,与纳米比亚罗辛矿床具有十分相似的成矿背景和特征。笔者以该铀矿床中的黑云母矿物作为研究对象,对该矿床中与铀成矿关系密切的黑云母等蚀变矿物开展系统研究,在此基础上讨论黑云母对成岩成矿的意义。1区域地质与矿床地质     

Unity of the national and the international in the socio-cultural development of the peoples of the USSR

International unity is becoming ever stronger in this country owing to an increasing similarity in the development of the cultural environment. This comprises the provision of all the country's republics with a sufficient number of schools, theatres, and other institutions and cultural information media in accordance with the needs of the population. An important part is played by the rise in ‘the general educational level, as well as the level of professional qualifications and skills. Among all the Soviet nations and nationalities, this rise being more rapid among formerly backward peoples. Prominent among the factors of internationalization is the progressive development of the nationalities’ cultural resources, while professional culture is being increasingly brought within the reach of the masses.The implementation of the nationalities policy promotes the all-round development of all Soviet nations and nationalities, their drawing together, the upsurge of the individual capabilities of every Soviet citizen.     

Deviation of the major axis of the inertia ellipsoid of the Moon from the direction toward the Earth

It is known from observations that the center of mass of the Moon does not coincide with the geometric center of its figure, and the line connecting these two centers is not aligned with the direction toward the center of the Earth, instead deviating toward the Southeast. This stationary deviation of the axis of the inertia ellipsoid of the Moon to the South of the direction toward the Earth is analyzed. A system of five linear differential equations describing the physical libration of the Moon in latitude is considered, and these equations are derived using a new vector method taking into account perturbations from the Earth and partly from the Sun. The characteristic equation of this system is obtained, and all five oscillation frequencies are found. Special attention is paid to the fifth (zero) frequency, for which the solution of the latitude libration equations are stationary and represents a previously unknown additional motion of the rotational axis of theMoon in a cone with a small opening angle. In contrast to the astronomical precession of the Earth, the rotation of the angular-velocity vector is in the positive direction (counter-clockwise), with the period T ₃ = 27.32 days. On this basis, this phenomenon has been named “quasi-precession.” This quasi-precession leads to a stationary inclination of the major axis of the inertia ellipsoid of theMoon to the South (for an observer on Earth), making it possible to explain one component of the observed deviation of the center of mass of the Moon from the direction toward the Earth. The opening angle of the quasiprecession cone is approximately 0.834″.     

Global repeating events in the history of the Earth and the motion of the Sun in the Galaxy

Chronological analyses of correlations between certain global repeating events (mass extinctions of marine organisms, meteorite impacts, and flashes in the frequency of geomagnetic reversals) during the Phanerozoic Eon and the motion of the solar system in the Galaxy are presented for five rotationally symmetrical models for the regular Galactic gravitational field. Thirteen of sixteen mass-extinction events can be described by a repetition interval of 183±3 million years. This is in agreement with the anomalistic period (interval between two subsequent passages of the Sun through the apocenter of its Galactic orbit) in the model of Allen and Martos. The positions of the minima and maxima in Gaussian functions approximating the frequency distribution for geomagnetic reversals also agree with the times of passage of the Sun through the apocenter and pericenter, respectively, of its Galactic orbit in this model. The maximum in the distribution of the deviations of the dates of mass extinctions from the nearest dates of impacts of large, crater-forming bodies is close to zero, providing evidence that many such events are correlated. As a rule, extinctions follow impact events. The impacts of large bodies have occurred most often when the solar system passes through the Galactic plane, while mass extinctions occur more often at some distance from the Galactic plane (about 40 pc). As a rule, intervals of increases in the frequency of geomagnetic reversals coincide with dates of impacts of large bodies. At the same time, these intervals do not show a clear correlation with the dates of mass extinctions. The intensity of mass extinctions, like the energy released by impacts, is consistently higher in periods when the Sun is moving from the apocenter toward the pericenter of its orbit, than when it is moving from the pericenter toward the apocenter. Thus, there is evidence for a variety of relationships between repeating global events in the Phanerozoic and the motion of the Sun in the Galaxy. Long-period variations in the frequency of geomagnetic reversals are correlated with the orbital motion of the Sun, and increases in the frequency of geomagnetic reversals are correlated with impacts. Mass extinctions are correlated with the impacts of large bodies, whose motions may have been perturbed by clouds of interstellar material concentrated toward the Galactic plane and by the shock front associated with the Perseus spiral arm, through which the solar system passes. The velocity of the Sun relative to the spiral pattern is estimated.     

摩擦桩基桩土间极限摩阻力取值问题探讨

通过对广珠东线高速公路横沥大桥的试桩及土体的工程地质条件分析,总结出影响摩擦桩基桩土间极限摩阻力取值的一般问题以及解决问题的方法和措施。     

从榴辉岩与围岩的关系论苏鲁榴辉岩的形成与折返

位于华北和扬子两板块碰撞带中的苏鲁榴辉岩形成的温压条件不但是超高压，而且是高温。榴辉岩的PTt轨迹表明其为陆-陆磁撞俯冲带的产物。榴辉岩的区域性围岩花岗质片麻岩为新元古代同碰撞期花岗岩，榴辉岩及其他直接围岩皆呈包体存在于其中，并见新元古代花岗岩呈脉状侵入榴辉岩包体中。区域性围岩新元古代花岗岩的锆石中发现有柯石英、绿辉石等包裹体，表明新元古代花岗岩的组成物质也经受过超高压变质作用，且榴辉岩与围岩新元古代花岗岩的锆石U-Pb体系同位素年龄基本相同。但新元古代花岗岩所记录的变质作用和变形作用期次（或阶段）却少于榴辉岩。椐上述可得如下推断：超高压榴辉岩与新元古代花岗岩岩浆是同时在碰撞带底部（俯冲板块前部）形成的；榴辉岩的第一折返阶段是由新元古代花岗岩岩浆携带上升的，其第二折返阶段是和新元古代花岗岩一起由逆冲及区域性隆起而上升，遭受剥蚀。     

某高速公路下伏煤矿采空区稳定性分析

在论述某高速公路下伏砦脖煤矿采空区地质、采矿和工程地质特征的基础上, 进行了稳定性数值模拟分析, 定性与定量地分析与评价了该煤矿采空区的地表变形特征及稳定性。研究结果表明: 该煤矿采空区的变形尚未完成, 对拟建的高速公路将产生很大的危害, 必须采取相应的工程治理措施。      

The Importance of the Precipitation and the Susceptibility of the Slopes for the Triggering of Landslides Along the Roads

In order to characterise the influence of the heavyrains on the observed landslides during the 1996–1997hydrological cycle, rainfall records for the last 100years are analysed from 104 stations in easternAndalusia. Regarding the amounts of rain recordedbetween October 1996 and March 1997 in the 104stations studied, 31 presented new all-time records;15 presented values that were 80–100% of thepre-1995 record; 49 stations, 80–50%; and 9stations, < 50%. A map has been devised of thesusceptibility of the materials through which thesouth-eastern Andalusian road network crosses,together with an inventory of the damage caused byinstability phenomena on banks and cuttings of theroad network during the winter of 1996–1997. Therelationships between the rainfall during the studyperiod, the damage caused to the road network and thesusceptibility of the materials affected are analysed.The results indicate that there is a clearcorrespondence between the rainfall recorded and thesusceptibility of the materials with the inventorieddamage. It is concluded that the widespread seriousdamage caused in early 1997 to the roads andsurrounding areas in the Alpujarra region and thecoast of the Province of Granada was mainly caused bythe extraordinarily heavy rains. However, considerablyless damage was observed where the susceptibility ofthe terrain is low, thus highlighting the extremeusefulness of terrain-susceptibility maps for riskprevention and territorial planning.     

On the consistency of proposed models for the Pyrenees with the structure of the eastern parts of the belt

The structure of the eastern Pyrenees consists mainly of south-directed thrusts involving basement and cover rocks. An antiformal stack developed by the piling up of basement thrust sheets which outcrop in the Axial zone. These structures account for a thin-skinned thrust model rather than a vertical fault model in which the Axial zone would be essentially autochthonous, and the North-Pyrenean fault the axial plane of a fan thrust system. New data from the Eastern Pyrenees and the thin-skinned model suggest that(1) the structure east of the Pedraforca nappe is similar to that of the Central Pyrenees; (2) the cover rocks of the South-Pyrenean units and of the Axial zone-after restoration—built up a northwards-thickening prism consistent with the existence of a unique Pyrenean sedimentary basin during Mesozoic time; (3) the Axial zone is only a complex antiformal stack developed as a part of South-Pyrenean system related to the Paleogene thrusting-tectonics. The Axial zone palaeogeographic area had no special meaning during Mesozoic time.