大兴安岭南段海流特高分异花岗岩锆石U-Pb年代学、地球化学及成矿意义

大兴安岭南段在晚侏罗世-早白垩世期间集中爆发有多期岩浆活动,深入讨论花岗岩岩石成因及岩浆演化过程对该地区中生代地球动力学背景及成矿作用研究具有重要意义。本文报道了海流特中粒二长花岗岩、细粒二长花岗岩、花岗伟晶岩的锆石LA-ICP-MS U-Pb年龄和全岩地球化学数据。海流特中粒二长花岗岩、细粒二长花岗岩、花岗伟晶岩的锆石²⁰⁶Pb/²³⁸U加权平均年龄分别为142.0±0.7 Ma、141.2±1.1 Ma、139.7±2.4 Ma,属早白垩世。样品主量元素表现为高硅、富碱,A/CNK值为1.01～1.18,平均1.09,属弱过铝质。微量元素富集Rb、Th、K等大离子亲石元素(LILE),亏损Ba、Sr、P、Ti等高场强元素(HFSE),Eu负异常明显(δEu=0.012～0.040),Zr+Nb+Ce+Y值介于38.25×10^-6～258.2×10^-6之间,小于350×10^-6,锆石饱和温度为723～778℃,未见原生白云母及碱性暗色矿物。岩浆演化过程中经历了斜长石、钾长石等...     

马来西亚麻元锡矿床成矿花岗岩地球化学、锆石U-Pb年龄及Sr-Nd-Hf同位素特征

麻元锡矿床是马来半岛东部花岗岩带内重要原生锡矿之一。为厘定矿区成矿花岗岩的形成时间及构造背景,本文开展了岩石学、锆石U-Pb年代学、岩石地球化学、Sr-Nd同位素及锆石Hf同位素研究。对2件矿区花岗岩样品的锆石进行了LA-ICP-MS U-Pb测试,获得了²⁰⁷Pb/²⁰⁶Pb-²³⁸U/²⁰⁶Pb谐和年龄分别为（259.0±3.3） Ma（MSWD=0.77）和（261.3±2.8） Ma（MSWD=0.55）,加权平均年龄为（260.30±2.0） Ma（MSWD=1.3）及（263.0±2.1） Ma（MSWD=0.15）。岩石地球化学分析显示,矿区花岗岩样品富Si O₂（73.09%～76.56%）、富K₂O（4.29%～4.91%）,I_A/CNK为1.03～1.06,轻稀土富集（LREE/HREE为4.24～8.08）,Eu负异常明显（δEu=0.08～0.20）,富含大离子亲石元素（Rb、K、Th、U）,亏损高场强元素（N...     

青藏高原东北缘茶卡北山地区印支期高分异花岗岩的发现及找矿意义

青藏高原东北缘茶卡北山地区发现了伟晶岩型Li-Be矿床,然而该地区尚未发现与成矿相关的花岗岩类侵入体,这也制约了成矿规律研究与成矿预测的开展。本文报道了茶卡北山地区新识别的阿斯合塔花岗岩的锆石、独居石U-Pb年龄、全岩地球化学、锆石Hf同位素、全岩Nd同位素资料。阿斯合塔岩体由黑云母花岗闪长岩、黑云母花岗岩和含石榴子石花岗岩组成;含石榴子石花岗岩锆石²⁰⁶Pb/²³⁸U年龄分散分布,主要介于248～232Ma,独居石²⁰⁶Pb/²³⁸U加权平均年龄为243.0±1.1Ma和246.3±1.0Ma。岩石具高SiO₂(76.56%～77.70%)和K₂O+Na₂O(7.81%～8.50%),低Fe₂O₃^T(0.50%～0.73%)和MgO(0.003%～0.072%)的特征,分异指数(DI)为94～96,铝饱和指数(A/CNK)为0.98～1.09,为弱过铝质高钾钙碱性系列...     

中祁连东段黑龙二长花岗岩地球化学、年代学及其构造意义

通过对中祁连东段黑龙二长花岗岩开展详细的年代学、岩石地球化学的分析测试和研究工作。LA-ICP-MS锆石U-Pb测年表明,黑龙二长花岗岩⁽²⁰⁶⁾Pb/(206)Pb/⁽²³⁸⁾U的加权平均年龄为(481.3±3.7)Ma(MSWD=4.6),属于早奥陶世。岩石地球化学的特征表明,黑龙二长花岗岩属于高碱钙碱性的I型花岗岩,岩石为准铝质-过铝质类型(A/CNK=0.91～1.22)。该二长花岗岩相对富集Rb、Th、U等大离子亲石元素,而相对亏损Nb、Ta、Ti等高场强元素,并且明显亏损P,显示出岛弧岩浆岩的信息。结合区域构造特征,认为黑龙二长花岗岩形成于活动大陆边缘弧的构造环境,同时,也佐证了北祁连洋盆双向俯冲的地质事实。     

滇西腾冲-梁河地区花岗岩锆石稀土元素组成和U-Pb同位素年龄

在详细的区域地质调查基础上,对滇西腾冲-梁河地区花岗岩的锆石进行了阴极发光观察,并通过LA-ICP-MS分析了其稀土元素组成和U-Pb同位素年龄。花岗岩中大部分锆石具有振荡环带,锆石稀土元素表现为亏损轻稀土、阶梯式富集重稀土、强烈正Ce异常及强烈负Eu异常,表明锆石为典型的岩浆锆石。花岗岩（D0053）锆石的²⁰⁶Pb/²³⁸U加权平均年龄为（127.9±1.0） Ma (MSWD=2.9,27个点),花岗岩（D4310）锆石的²⁰⁶Pb/²³⁸U加权平均年龄为（58.3±0.5） Ma (MSWD=1.8,21个点),表明腾冲-梁河地区存在大量早白垩世和早第三纪花岗岩浆活动,它们是特提斯演化过程的岩浆响应。     

冈底斯中段容果地区二长花岗岩锆石U-Pb年龄及其地球化学特征

为确定容果地区二长花岗岩的形成时代、成因及其地质意义,对容果地区二长花岗岩进行了岩相学、LA-ICP-MS锆石U-Pb年龄及地球化学研究。结果表明: 二长花岗岩中的锆石为岩浆成因,²⁰⁶Pb/²³⁸U年龄加权平均值为(69±1) Ma,侵入时代属于晚白垩世; 二长花岗岩中Al₂O₃含量为13.83%~14.41%,Na₂O含量为3.68%~3.94%,K₂O含量为4.28%~4.35%, K₂O/Na₂O为1.08~1.18,相对富钾,铝饱和指数A/CNK平均为1.02,属弱过铝质岩石; 微量元素特征表现为相对富集Rb、U、K等大离子亲石元素,亏损Nb、Ta、Ti等高场强元素的特征。结合区域构造演化背景,可得出在80~69 Ma之间,该区的岩浆活动并未停止,仍然持续在发生,所生成的岩体是新特提斯洋壳俯冲的岩浆产物,形成于造山环境下,形成过程贯穿整个造山运动。     

湘东光明萤石矿黑云母花岗岩地球化学特征及其对萤石成矿的启示

光明萤石矿产出于湘东锡田岩体北部,为探究矿区内黑云母花岗岩与萤石成矿的关联,对岩体和萤石矿体进行了系统的地球化学研究,并利用LA-(MC)-ICP-MS对黑云母花岗岩中锆石开展了U-Pb年代学、微量元素及Hf同位素地球化学研究。结果显示,黑云母花岗岩具有高硅(SiO₂=72.62%～77.34%)、高碱(Na₂O+K₂O=6.03%～8.66%)、富铝(Al₂O₃=12.02%～13.83%)特征,A/CNK值介于1.07～1.14之间,为过铝质花岗岩。3个样品低U锆石的²⁰⁶Pb/²³⁸U年龄加权平均值在215～218 Ma之间,指示花岗岩侵位于印支期。矿区黑云母花岗岩印支期—燕山期锆石年龄为237～133 Ma,在230～210 Ma、190～170 Ma、150～130 Ma存在3个较集中的年龄峰期,暗示岩浆侵位后受到热事件影响,推测矿区岩浆活动具有多阶段性。黑云母花岗岩岩体有较强的负Eu异常,且富集大离子亲石元素Rb、Th、U...     

东昆仑东段早泥盆世“A”型花岗岩的确定——来自乌兰东地区都南哑合黑云母花岗岩锆石U-Pb年代学、元素地球化学证据

都南哑合岩体位于东昆仑东段乌兰东呼德生地区,通过对岩体锆石U-Pb定年和岩石地球化学进行研究,分析该岩体成因及构造背景。结果表明：都南哑合岩体主要为黑云母花岗岩,锆石²⁰⁶Pb/²³⁸U加权平均年龄为(413.3±2.1) Ma,岩体结晶年龄为早泥盆世;岩石属准铝质-过铝质高钾钙碱性系列,具高硅,SiO₂=71.13%～74.67%、富碱,Na₂O+K₂O=8.3%～9.26%,低铝,Al₂O₃=12.28%～13.56%、贫钛,0.15%～0.31%、贫镁,0.22%～0.34%及富钾特征。K₂O/Na₂O=0.69～1.64,平均1.36;稀土元素分布曲线呈强负铕,δEu=0.18～0.42,平均0.26,异常轻稀土富集的右倾型;富集大离子亲石元素Rb,K和高场强元素Th,La,Ce,Nd。Ba相对亏损,Sr强亏损;明显亏损高场强元素P,Ti,弱富集Nb,Ta,Sm,Zr,Hf,Y,Yb...     

西藏梅巴切勤地区晚三叠世斑状二长花岗岩锆石 U-Pb年代学、地球化学特征及地质意义

为了研究拉萨地块晚三叠世岩浆活动的动力学背景,对梅巴切勤斑状二长花岗岩开展了野外地质调查、岩石学、地球化学和年代学研究工作。利用LA-ICP-MS测得2件斑状二长花岗岩样品的锆石²⁰⁶Pb/²³⁸U年龄加权平均值为(202.3±2.2)Ma (MSWD=2.6)和(203.2±1.6)Ma (MSWD=0.24),表明其岩浆活动发生在晚三叠世。岩石为高钾钙碱性系列,具有高硅[w(SiO₂)=70.78%～76.69%]、高铝[w(Al₂O₃)=12.93%～14.97%]、富钾[w(K₂O)=4.14%～5.06%]的特征,铝饱和指数(A/CNK)为1.06～1.28,为过铝质花岗岩;相对富集大离子亲石元素Rb、K和不相容元素Zr、Hf,亏损Ba、Ta、Nb、Sr、P、Ti等元素;稀土元素总量在(124.63～306.19)×10^-6之间,轻稀土元素明显富集,轻重稀土元素分馏较强,具明显的负Eu异常(δEu=0.12～0.68);岩石...     

铀矿区花岗岩锆石定年的“高铀效应”:来自鲁溪和下庄花岗岩SHRIMP锆石U-Pb年龄的启示

下庄铀矿田是我国最重要的花岗岩型铀矿田之一,其中的复式花岗岩体已获得了一批锆石U-Pb年龄,基本上构筑了下庄铀矿田加里东、印支和燕山多期多阶段的岩浆演化系列。分析前人数据发现,不同学者获得的同一岩体的锆石U-Pb年龄差别较大,最大相差达17 Ma,主要原因之一可能是高U锆石的存在导致了加权平均年龄可靠程度的降低。针对这一问题,笔者以下庄铀矿田鲁溪粗粒黑云母花岗岩和下庄中粒黑云母花岗岩为研究对象,采用SHRIMP锆石U-Pb法测试U-Th-Pb含量,重点分析了锆石U含量对²⁰⁶Pb/²³⁸U年龄的影响,并厘定了这两个岩体的侵位年龄。测试结果显示,鲁溪粗粒黑云母花岗岩38颗锆石的U含量变化于152×10^–6～5687×10^–6之间, ²⁰⁶Pb/²³⁸U年龄变化于234～1345 Ma之间,可分为五组,其中年龄最小一组由27颗锆石组成,变化于234～265 Ma之间,加权平均年龄为247.3±3.2 Ma, MSWD=3.9;下庄中粒黑云母花岗岩18颗锆石的U...     

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。      

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。     

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.     

混凝剂处理钻井废泥浆液的研究

通过烧杯搅拌实验对混凝剂处理钻井废泥浆液进行研究,从混凝剂适应p H值范围、混凝效果、沉降速度三方面研究比较,找出一种较为理想的混凝剂,并分析了影响混凝剂性能的主要因素,确定了混凝剂的最佳投放剂量。      

黄河源区水环境变化及黄河出现冬季断流的原因

自1954年有水文观测资料以来，黄河曾在青海省玛多县黄河沿水文站发生过3次断流。本文在分析黄河源区水环境特征及其影响因素的基础上指出，鄂陵湖、扎陵湖的环湖融区调节能力低，当遇到连续干旱、冬季其调节水量不足以维系黄河径流时便会发生断流，这是断流的主因。湖水位降低、开采沙金、过度放牧等自然和人为因素也会对黄河发生断流产生影响。鄂陵湖口附近黄河上修建的水电站开始蓄水，提高了两湖及环湖融区的调节能力，今后黄河冬季出现断流的可能性将大为降低。     

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.     

The evolution of the magmatism in the external zones of the Betic Cordilleras during the mesozoic

Abstract

The Mesozoic igneous rocks from the External Zones of the Betic Cordilleras extend for some 300 km along the Subbetic Zone. They are poorly differentiated basic rocks which, altogether, correspond to a transitional series containing tholeiitic and sodium-alkaline terms. They crop out as small ophite stocks and dykes intruded into middle- and upper-Triassic rocks, or as submarine flows and sills interlayered with Jurassic materials.

Geological and radiometric evidence points to an upper-Triassic-Liassic age for the ophite-generating magmatism, while the fissure volcanism began locally in the early-Liassic and extended throughout the Dogger. It reached its climax in the Tithonian and ceased abruptly in the lowermost Cretaceous.

The magmas that generated the two groups of rocks originated within the mantle. During the ascent through a continental crust they were contaminated by deep-crust granitoid rocks and by the assimilation of pelites from the basement. The chemical composition and fractional-crystallization differentiation trends of the ophites belong to the tholeiitic series, while those of the middle-uppermost Jurassic magmas to the sodic-alkaline series. This magmatic evolution may be attributed to a geodynamic change from distensive in the Triassic to transtensive from the middle-Jurassic onwards.     

悬板开孔对排沙漏斗流场特性的影响

排沙漏斗的水沙分离性能取决于其流场特性,为了弄清楚悬板开孔对流场特性的影响,利用粒子图像测速技术和数值模拟方法,分别对悬板溢流段和非溢流段同时均匀布孔、仅在非溢流段布孔和无孔时的排沙漏斗流场特性开展研究。结果表明：①布孔位置不影响涡流性质但影响其强度,均匀布孔时涡流强度最小,不利于水沙离心分离;②无孔和仅在非溢流段布孔时的流场特性有利于泥沙径向输移、沉降和排出,均匀布孔径向速度和二次流流速减小不利于泥沙输移和排出;③仅在悬板非溢流段布孔时悬板表面速度大于其他方案,泥沙不易淤积于悬板。为减少悬板上的泥沙淤积量且同时要保证较高的泥沙截除率时可采用仅在悬板非溢流段布孔的方案优化悬板体型。     

On the Validity of the Boussinesq Approximation for the Elder Problem

The Elder problem is an example of a density driven flow, motivated by experiments of a thermally driven convection in porous media. It is a mathematical benchmark problem used for code verification of density driven flow simulators and comparison of issues related to its numerical treatment. Its bifurcation diagram with respect to the Rayleigh number is investigated on a hierarchy of uniformly refined grids. Eleven stationary solutions are shown to exist for the Elder problem. Similar solutions can be found using the Boussinesq approximation. Despite this similarity the corresponding bifurcation diagrams are shown to be topologically not equivalent. This gives rise to serious doubts on the validity of Boussinesq approximation for this model problem. Grid convergence is investigated for the numerically obtained solutions.