柴北缘牦牛山组火山岩锆石U Pb年龄及其地质意义

柴北缘牦牛山组磨拉石建造不整合覆盖在前泥盆系之上,记录了该地区早古生代洋盆关闭的时间。对柴北缘牦牛山一带牦牛山组上部火山岩段两个流纹质熔结凝灰岩样品进行锆石U Pb同位素测定,两个样品的岩浆锆石206Pb/238U年龄加权平均值分别为(3965±24) Ma(n=17,MSWD=33)和(3958±12) Ma(n=20,MSWD=11),均被解释为火山岩喷发年龄。结合东昆仑造山带牦牛山组测年结果,认为柴达木盆地周缘牦牛山组火山岩形成时代为晚志留世—晚泥盆世,且东昆仑与柴北缘加里东造山作用结束的时间均为早泥盆世之前,而非传统认为的晚泥盆世。     

柴达木盆地北缘牦牛山组物源分析及其构造意义

柴达木盆地北缘牦牛山组为一套由砂砾岩组成的陆相紫红色粗碎屑沉积岩,其时代一直存在争议。本文对两个剖面牦牛山组的沉积特征、古水流、砾石成分进行了研究,并对砂质充填物中锆石进行了LA-ICP-MS测年分析。结果表明,牦牛山组发育冲击扇沉积,古流向主要为自北西至南东和自南东至北西两个方向。两个剖面砾石成分差异显著,城墙沟剖面砾石成分以碳酸盐岩为主,而旺尕秀剖面砾石成分则较为复杂。砂质充填物中碎屑锆石U-Pb年龄可分为3个组:360～560Ma、890～1050Ma和2200～2500Ma。它们代表本区3次构造事件,包括早古生代柴达木盆地北缘由洋-陆至陆-陆的碰撞过程,新元古代Grenville造山事件及新太古代陆壳的增长。其中最小的碎屑锆石U-Pb年龄为365±3Ma,结合区域地质背景与古生物等资料,表明牦牛山组的时代为晚泥盆世。本区早古生代第三期和第四期花岗岩类的锆石U-Pb年龄与本文最年轻的一组锆石U-Pb年龄在误差范围内一致,表明这两期岩体发生了快速抬升剥蚀。结合前人研究,柴达木盆地北缘在牦牛山组沉积期处于后碰撞阶段。     

四川木里梭罗沟金矿床成因讨论:来自年代学和硫、铅同位素的约束

四川木里县梭罗沟金矿床是甘孜-理塘金矿带上目前已查明资源储量最大的金矿床,但是其矿床成因研究薄弱,制约了深部找矿勘探工作.本次研究对其赋矿岩石和含金矿脉的锆石U-Pb年代学、载金矿物黄铁矿和毒砂的硫、铅同位素开展了研究.结果表明,梭罗沟金矿床赋矿岩石的锆石U-Pb年龄为(252.8±2.3)Ma(MSWD=0.4,n=18),指示赋矿岩石为晚三叠世曲嘎寺组碎屑岩基质中的晚二叠世玄武岩岩块.含金矿脉碎屑锆石U-Pb年龄具有4个较明显的峰值,分别为119 Ma、255 Ma、526 Ma和962 Ma.最年轻的碎屑锆石年龄为(119±1.7)Ma(MSWD=0.2,n=13),指示梭罗沟矿床深部可能有隐伏的早白垩世花岗岩,并且金成矿时代晚于119 Ma.金成矿热液期的黄铁矿和毒砂的?34S值范围为4.8‰～7.79‰(平均值为6.2‰),与造山型金矿床的硫同位素相似.黄铁矿的206Pb/204Pb平均值为18.47、207Pb/204Pb平均值为15.63和208Pb/204Pb平均值为37.74,与造山带铅同位素演化一致.结合矿床地质特征,梭罗沟金矿床受晚白垩世-古近纪的韧性剪切带和走滑断裂控制,其成矿时代为119～27 Ma之间,其矿床类型为造山型金矿床.     

柴北缘HP-UHP变质带多期构造热事件的再厘定:鱼卡地区高压变泥质岩锆石和独居石U-Pb定年

柴北缘高压-超高压变质带西段鱼卡地区变泥质岩中夹有榴辉岩透镜体,已有的研究显示变泥质岩的变质程度也达到了榴辉岩相,并与榴辉岩一起经历了高压-超高压变质作用,是柴北缘曾经历早古生代大陆深俯冲作用的直接证据,也是研究柴北缘大陆深俯冲过程重要的岩石"探针"。本文选择柴北缘西段鱼卡超高压变质单元中的3件蓝晶石榴白云母石英片岩HP变泥质岩样品分别进行了SHRIMP、LA-ICP-MS锆石和原位独居石U-Pb定年。样品Q06-1-2的锆石给出了920±18Ma(MSWD=1.3)的加权平均年龄,其CL图像特征和极低的Th/U比显示其为变质年龄,代表了与罗迪尼亚超大陆碰撞拼合相关的变质事件。样品A03-11-2.2的锆石给出了450±7Ma(MSWD=0.2)的年龄,认为其代表变泥质岩的榴辉岩相变质年龄。样品A03-14-11的薄片原位独居石定年给出了439±8Ma(MSWD=0.072)的加权平均年龄,结合岩相学观察,认为其可能为榴辉岩相峰期之后的早期退变质年龄。这些资料显示柴北缘鱼卡地区早古生代大陆深俯冲的时限为440~450Ma。结合已有研究资料,鱼卡高压变泥质岩记录了新元古代早期和早古生代两期变质事件,进一步证明了柴北缘地区经历了格林威尔期和早古生代两期造山事件     

柴北缘前寒武纪岩体（地层）变质年龄 及其对早古生代造山作用的指示

柴北缘前寒武纪岩体（地层）分布广泛。为确定柴北缘地区前寒武纪岩体（地层）受早古生代碰撞造山作用的影响,采用LA-ICP-MS技术,对大柴旦地区前寒武纪黑云斜长片麻岩、斜长角闪岩及石榴子石斜长角闪岩中的锆石进行了U-Pb同位素定年。黑云斜长片麻岩获得479~472Ma的变质年龄,斜长角闪岩获得440Ma和470Ma 2个变质年龄,石榴子石斜长角闪岩获得418.8Ma±3.0Ma的变质年龄。初步确定,柴北缘早古生代造山作用对前寒武纪岩体构成了3次强度不等的变质作用叠加,分别为大洋俯冲末期阶段(495~467Ma)岛弧花岗岩弱热烘烤变质作用、大陆碰撞造山阶段(467~423Ma)区域变质作用、S型花岗岩热动力变质作用和大陆后碰撞造山阶段(423~371Ma) I型花岗岩强烈接触热变质作用。     

西昆仑康西瓦断裂西段斜长片麻岩LA-ICP-MS锆石U-Pb定年及其构造意义

在康西瓦断裂西段发育着一套含石榴子石二云斜长片麻岩。根据锆石的阴极发光图像和Th、U、REE等特征,锆石可分为岩浆成因和变质热液成因2类。利用LA-ICP-MS法进行锆石U-Pb定年,测得含石榴子石斜长片麻岩的源岩形成年龄为254.5Ma±4.2Ma(MSWD=0.16),变质年龄为242.7Ma±2.3Ma(MSWD=0.11)。结合区域地质资料,含石榴子石二云斜长片麻岩的变质作用与古特提斯碰撞造山有关,表明西昆仑造山带在中三叠世早期(243Ma)仍处于古特提斯碰撞造山期。     

赣东北地区双桥山群碎屑锆石U-Pb年代学研究

双桥山群是赣东北地区重要的岩石单元之一,其年代学研究一直备受关注。本文对赣东北地区双桥山群凝灰质板岩和粉砂质板岩中的碎屑锆石进行了LA-ICP-MS U-Pb测年分析。碎屑锆石年代学测试结果显示4个主要年龄区间:591～634 Ma(峰值601 Ma)、803～837 Ma(峰值831 Ma)、866～1019 Ma(峰值910 Ma)和 1800 Ma。其中最年轻的碎屑锆石年龄组591～634 Ma峰期601 Ma的年龄,可能限定了双桥山群最大的沉积年龄;而803～837 Ma(峰值831 Ma)指示其物源可能源于江南造山带东段新元古代造山过程的岛弧火山岩; 866～1019 Ma峰期年龄为910 Ma的年龄与皖南-赣东北地区的基性火山岩、火山碎屑岩的形成时代基本一致; 1800 Ma的年龄组与扬子陆块1.8～1.9 Ga锆石年龄相一致。赣东北地区双桥山群碎屑锆石U-Pb测年结果中,出现828 Ma和1800 Ma的碎屑锆石特征年龄峰值,显示它们具有与扬子地块的亲缘性,同时又含有大量的～1.0 Ga碎屑锆石,这些特征年龄相似于格林威尔期的华夏地块,说明在新元古代晚期存在的沉积盆地具有来自扬子和华夏板块的双向物源。     

东昆仑牦牛山组流纹岩锆石U-Pb年龄及构造意义

东昆仑水泥厂地区造山后火山-沉积盆地内形成的牦牛山组磨拉石建造不整合覆盖在前泥盆系地层之上,其形成时代的研究对限定东昆仑早古生代洋盆关闭的时间具有重要意义。应用激光烧蚀多接收器电感耦合等离子体质谱仪(LAMC-ICPMS)方法,对火山-沉积盆地内牦牛山组不同层位的流纹岩夹层进行了精确的锆石U-Pb定年研究。结果表明,盆地北缘牦牛山组底砾岩之上的流纹岩(B743-2)中岩浆锆石~(206)Pb/~(238)U年龄平均值为423.2±1.8Ma,盆地西缘牦牛山组底砾岩之上的流纹岩(B820-1)中岩浆锆石~(206)Pb/~(238)U年龄平均值为408.2±2.4Ma,盆地西缘和南缘牦牛山组中上部碎屑岩中流纹岩夹层(B705-1和B656-1)的岩浆锆石~(206)Pb/~(238)U年龄平均值分别为404.9±4.8Ma和399.6±2.8Ma。它们代表了牦牛山组不同层位火山岩的形成年龄,由此可以限定水泥厂地区牦牛山组形成时间为400～423Ma。上述年代学结果较为精确地限定了东昆仑早古生代洋盆关闭的构造年代。流纹岩中2486～920Ma元古代继承锆石的发现,说明东昆仑南的变质基底和扬子板块变质基底类似,是晋宁期0.9～1.0Ga罗迪尼亚超大陆形成时发育起来的。     

青海德令哈石底泉地区牦牛山组火山岩LA-ICP-MS锆石U-Pb年龄及地质意义

本文对德令哈市石底泉地区牦牛山组火山岩进行了年代学、岩石学和地球化学研究,主量元素和微量元素分析结果显示岩石具有高钾高钠,贫铁镁的特征,属中酸性岩类,具有岛弧火山岩的地球化学特征。牦牛山组上部火山岩段的安山岩LA-ICP-MS锆石U-Pb年龄为395.7±2.7Ma,确定其形成时代不晚于早泥盆世,而不是传统认为的晚泥盆世,为柴达木盆地北缘早古生代的构造演化提供新的年代学依据。综合分析表明,石底泉地区牦牛山组火山岩为活动大陆边缘构造环境的产物,其形成与板块俯冲作用密切相关。     

皖南歙县花岗闪长岩构造变形、 年代学及其地质意义

位于江南造山带北缘的歙县地区,有大量的花岗质岩体出露。本文对歙县花岗闪长岩体进行了构造变形分析和LA-ICP-MS锆石U-Pb测年。构造变形特征显示该地区花岗闪长岩曾遭受深层次韧性变形,其中广泛发育的波状消光、动态重结晶颗粒、旋转残斑、云母鱼等是矿物受应力作用发生韧性变形的指示,花岗闪长岩中石英和长石的变形行为指示韧性变形温度为500 ℃～580 ℃。对歙县地区花岗闪长岩测年,获得加权平均年龄为822.8±9.5 Ma（MSWD = 0.55,n = 23）,代表岩体的侵位年龄。综合前人研究资料,我们认为景德镇—歙县构造带内的岩石韧性变形时代应该在770 Ma左右,其可能反映了扬子板块与华夏板块最终碰撞拼合。     

东濮凹陷北部沙河街组三段中亚段沉积环境分析

东濮凹陷北部沙三中亚段广泛发育盐岩和烃源岩,这两个看似不能共存的物质却在这里互层共生。该时期研究区沉积特征为多盐韵律与多层烃源岩互层共生、连续沉积,单个盐韵律厚度从几米到十几米,烃源岩有机质丰度高、类型好。平面上,两者在湖盆沉积沉降中心共生;垂向上,高有机质丰度、好干酪根类型与高盐度地层具有较好的对应关系。因而成为恢复古气候和古环境的重要研究对象。通过岩石学、古生物学以及Sr/Ba、B/Ga、(V+Ni+Mn)、Fe/Mn、Sr/Cu、Mg/Ca、V/(V+Ni)、稀土元素含量和氯同位素等方法对凹陷北部沙三中亚段的沉积环境进行研究。结果表明,凹陷北部沙三中亚段为深水沉积的还原环境,古盐度较高,达到半咸水-咸水沉积;微量元素和孢粉化石特征表明研究区沙三中亚段为温暖潮湿的环境。     

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.     

郯庐断裂南段研究进展与断裂性质讨论

据1：5万区域地质调查和专题研究资料，就郯庐断裂带是否南延与消失的原因，其与大别—苏鲁造山带交截形成的假位错效应，以及与中新生代沉积盆地形成演化的关系等作了新的阐述。在此基础上，讨论了郯庐断裂带是否为巨大的左行平移断层或转换断层。认为郯庐断裂带可能是在“古郯庐带”的基础上于早侏罗世重新活动、白垩纪强烈活动的地堑型枢纽断裂带。     

塘口水电站坝基岩体透水性和渗漏问题分析

塘口水电站大坝基础座落在断层和裂隙较发育的龟裂纹灰岩上,岩体完整性差、透水性强,多年运行后,大坝灌浆廊道和排水廊道出现多处集中性漏水,为确保大坝安全和电站正常发电,根据渗漏性质和成因,采用对灌浆廊道补充帷幕灌浆,对排水廊道进行固结+帷幕+回填灌浆。通过灌浆处理后,效果良好,表明灌浆工程有效的将导致坝基渗漏的上下游的裂隙通道封闭,并顺利的经受了随后的汛期洪水考验,大坝安全得到保障。     

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.     

Calculation of the Inverse of the Covariance

In reservoir characterization, the covariance is often used to describe the spatial correlation and variation in rock properties or the uncertainty in rock properties. The inverse of the covariance, on the other hand, is seldom discussed in geostatistics. In this paper, I show that the inverse is required for simulation and estimation of Gaussian random fields, and that it can be identified with the differential operator in regularized inverse theory. Unfortunately, because the covariance matrix for parameters in reservoir models can be extremely large, calculation of the inverse can be a problem. In this paper, I discuss four methods of calculating the inverse of the covariance, two of which are analytical, and two of which are purely numerical. By taking advantage of the assumed stationarity of the covariance, none of the methods require inversion of the full covariance matrix.     

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。      

Report of the restudy of the defined global stratotype of the base of the Silurian System

The Global Stratotype Section and Point （GSSP） for the base of the Silurian System was defined in 1985. Since that time, a number of researchers have suggested that this section has serious deficiencies for use as a GSSP. As a result, in 2000, the Subcommission on Silurian Stratigraphy （SSS） proposed undertaking a formal restu@ of this GSSP, which was subsequently approved by the International Commission of Stratigraphy （ICS）. The result of this restudy was the formal proposal that the current GSSP, at 1.6 m above the base of the Birkhill Shale, at Dob＇s Linn, Scotland, should be maintained as the same locality and stratigraphic level, but the bios- tratigraphical definition of the boundary should be revised. The previously defined, basal Silurian grapto- lite zone, the Parakidograptus acuminatus Zone, should be subdivided into a lower Akidograptus ascensus Zone and a higher E acuminatus Zone. The base of the A. ascensus Zone, marked by the first appearance of A. ascensus, should be regarded as the biostratigraphic mark for the base of the Silurian. This proposal has now been formally approved by the SSS and ICS, and ratified by International Union of Geological Sciences. This is the first GSSP to undergo formal restudy and redefini- tion, and the proposal also included a recommended procedure for restudy of GSSPs.     

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″.     

Artemia in the Salt Lakes of Russia:the Productivity of Populations,the Reserves of the Cysts and the Fisheries

正Artemia cysts are an extremely important component of aquaculture diets.It is well established that the cultivation of fish and shellfish derive substantial health and growth advantages when Artemia are included in the diets of the