赣东北景德镇双桥山群火山碎屑凝灰岩锆石U-Pb年龄及Hf同位素特征

为探讨赣东北景德镇地区双桥山群的沉积时代与物质来源,对该区双桥山群安乐林组地层中发育的一套变火山碎屑凝灰岩夹层进行了年代学、地球化学及锆石Lu-Hf同位素研究。结果显示,该套火山碎屑凝灰岩的岩性主要为英安岩、安山岩,凝灰岩的LA-ICP-MS锆石U-Pb年龄为(809±2)Ma,表明该套岩石形成于新元古代。凝灰岩锆石的Hf同位素组成变化范围较广,其中二阶模式年龄为1426~2313 Ma,主要集中于1.7~2.3 Ga之间,其ε_(Hf)(t)均为负值-2.6~-16.5,t_(DM2)模式年龄远大于U-Pb年龄,表明该组岩石的岩浆来源于元古代地壳物质的再循环。     

三江造山带兰坪盆地东缘火山岩锆石U-Pb年代学、Hf同位素组成

青藏高原东南缘"三江"复合造山带南、北两段发育若干火山-岩浆岩带,随着火山岩年代学、地球化学数据的积累,其时空关系渐趋清晰。但由于中-新生界沉积覆盖,这些火山岩带向南常终止于兰坪盆地附近,致使火山岩时空构架不明。兰坪盆地东部弥沙地区出露盆地基底岩石,由两个构造层组成,上部为碎屑岩及生物碎屑灰岩,下部出现大量火山碎屑物质。含火山岩段出露厚约150m,可分为三个喷发-沉积韵律,由流纹质熔结凝灰岩、晶屑岩屑熔结凝灰岩组成的火山碎屑岩与紫红、灰黑色泥岩、大理岩组成的沉积岩相间组成。火山岩锆石LA-ICP-MS U-Pb数据表明,岩浆活动始于或早于258Ma,一直持续到248Ma。锆石原位Lu-Hf分析结果显示,早期岩浆包含较多幔源物质,而晚期岩浆则几乎完全由古老地壳局部熔融形成。本文提供的新数据表明,兰坪盆地东缘火山岩与三江造山带其它地区古特提斯洋俯冲阶段火山岩具有一致的年代学组成、相同的Hf同位素变化规律,可能属于发育在扬子板块西缘之上江达-维西-云县弧火山岩带。     

云南保山东缘早古生代高Si花岗岩的成因及构造意义

对保山地块东缘高Si花岗岩开展矿物化学、岩石地球化学及锆石U Pb Hf系统研究,结果表明该高Si花岗岩为具钙碱性、强过铝质特征的S型花岗岩。锆石U Pb同位素分析表明,高Si花岗岩侵位于454 Ma,并含有800~1 100 Ma的继承锆石。锆石Hf同位素分析表明其岩浆锆石具有与青藏高原及东南缘同时代长英质侵入体相似的Hf同位素组成,暗示其相似的岩浆起源。矿物化学、同位素组成及Melts模拟计算结果表明,保山东缘高Si花岗岩为一系列复杂作用的结果：高硅花岗岩母岩浆起源于该区沉积岩部分熔融;熔体形成后经高度分异演化,在侵位过程中同化混染围岩;岩浆冷凝至固相线下部分矿物再平衡。保山东缘高Si花岗岩体与平河花岗岩体具相似年龄和地球化学特征,暗示它们之间可能存在类似的成因机制。     

碎屑沉积岩/沉积物Sm-Nd、U-Pb与Hf同位素的化学地球动力学意义

碎屑沉积岩能有效记录它们的源区。碎屑沉积岩的Nd同位素组成及其中锆石U-Pb年龄与Hf同位素组成是解析碎屑物质源区、源区壳-幔相互作用及不同块体间相互作用的关键方法。全岩/全样的Nd模式年龄可以指示其源区地壳从亏损地幔分离的平均时间,而锆石Hf同位素模式年龄能够揭示出所测锆石颗粒其形成时的源区特征。细粒碎屑沉积岩/沉积物化学组成代表了其源区上地壳在风化、搬运、沉积过程中不溶于水的Nb、Ta、Zr、Hf、Sc、Ti、Th、REE等的平均组成。实践表明,华北板块、扬子板块、以大兴安岭为代表的中亚造山带东部具有明显不同的形成与演化历史。大兴安岭的地壳增生主要发生于新元古代—古生代期间。由碎屑沉积岩进行化学动力学分析时,应充分系统考虑地质过程的复杂性,将宏观与微观相结合、局部与整体相结合。     

胶东文登长山南花岗闪长岩体的岩浆混合成因：闪长质包体及寄主岩石的地球化学、Sr-Nd同位素和锆石Hf同位素证据

胶东昆嵛山杂岩文登长山南花岗闪长岩体中广泛分布具有火成结构的闪长质包体,这些包体主要为椭圆形或纺锤形,定向排列,大小不等(几cm至几m),颜色较寄主岩深,粒度较细。包体具有与寄主岩石相似的矿物组合,但铁镁质矿物及斜长石含量明显比寄主岩石高,而石英和钾长石含量低于寄主岩石;镜下包体具有明显的不平衡反应结构,广泛发育针状磷灰石。在地球化学特征上,包体和寄主岩石部富集大离子亲石元素和轻稀土元素,亏损高场强元素,并具有相近的Sr、Nd同位素组成,ISr为0．70784-0．70818,εNd为-15．0--15．5。然而,包体和寄主岩石的主量元素在相关图上呈明显的线性关系, 并且岩石学和锆石Hf同位素特征也明显表明文登长山南岩体在成岩过程中发生了镁铁质岩浆和长英质岩浆的混合作用。在岩浆混合作用过程中,全岩Sr、Nd同位素和晚期生成的矿物组成比较快速地达到了均一化,而主量元素和高温矿物锆石Hf同位素组成则残留了原始岩浆的部分特征。研究表明,锆石Hf同位素在岩浆混合作用过程中不容易达到同位素平衡,其同位素组成比全岩Sr、Nd同位素更能有效地示踪混合岩浆的源区特征和岩浆混合过程。     

川北九寨沟地区隆康熔结凝灰岩锆石 LA-ICP-MS U-Pb年龄

康县-琵琶寺-南坪构造带内出露的一套变质沉积-火山岩系与勉略洋的构造演化具有密切的关系.在该构造带西段九寨沟塔藏-隆康地质剖面东端出露近百米厚的安山质熔结凝灰岩、层凝灰岩,在隆康、牙扎沟附近采集了熔结凝灰岩样品(JZG-L),选出百余颗锆石.锆石LA-ICP-MS U-Pb分析结果表明,锆石发育典型的岩浆锆石韵律环带,U和Th含量分别为35×10-6 ～750×10-6和31×10-6～717×10-6,Th/比值介于0.44～1.30之间,为典型的岩浆锆石,该样品获得的206Pb/238U加权平均年龄为246.2Ma+2.8Ma(MSWD=2.6,n=12,2ó).此外,样品中还包括其他多种类型的碎屑锆石,其中最老的碎屑锆石的谐和年龄为(2481+33)Ma,表明九寨沟地区存在前寒武纪基底.结合区域地质及该区火山岩的发育特征,246Ma的锆石U-Pb年龄的获得为勉略缝合带西延至南坪一带提供了重要的同位素年代学证据.     

花岗质岩浆作用及后期演化过程：来自矿物原位微区成分与同位素组成的制约

花岗岩作为大陆地壳的重要组成部分,其岩浆作用过程一直是地学领域研究的热点。传统上利用全岩地球化学和同位素数据来示踪花岗岩成因和演化过程的方法已不够准确,为此,本文系统总结了近年来报导的花岗岩中单矿物的原位微区成分——这些数据记录了全岩数据无法识别的单矿物颗粒内部和不同矿物颗粒之间元素和同位素组成的变异特征,明显提高了对花岗质岩浆作用及后期演化过程的认识。首先,矿物原位微区成分对花岗质岩浆的源区性质和混合过程具有指示意义。花岗岩中岩浆锆石Hf同位素组成的变异可能暗示其源区在深熔作用过程中发生了锆石的不平衡和选择性熔融,而未必是壳幔混合作用的结果,这是对“锆石效应”概念新的扩展;同一花岗岩样品中分选出的磷灰石颗粒可以具有完全不同的稀土元素配分模式、Eu异常、Sr含量和Sr-Nd同位素组成等,表明它们中的部分颗粒是岩浆形成和上升过程中从围岩捕获的,是小规模地壳混染作用的产物;榍石的微区成分分带记录了多种岩浆混合过程,也反映了熔体成分、氧逸度和温度等因素的变化;花岗岩与其中发育的包体、捕虏体和相关围岩的锆石Hf-O同位素和磷灰石Sr-Nd同位素组成可以记录上述岩石在形成过程中经历岩浆混合和同化...     

皖南祁门地区东源钨钼矿区花岗闪长斑岩SHRIMP锆石U-Pb年龄和Hf同位素特征

江家等系列花岗闪长斑岩是皖南祁门县东源钨钼矿区含矿岩体的组成部分,位于东源花岗闪长岩的西侧。对江家和方村花岗闪长斑岩进行的SHRIMP锆石U-Pb测年结果表明,江家、方村花岗闪长斑岩的结晶年龄为149~152Ma,与富钨的东源花岗闪长岩相近。岩石地球化学和锆石Hf同位素分析显示,江家等系列花岗闪长斑岩源区具有复杂的多成分端元,其中老锆石核的正εHf值反映了成岩岩浆对晋宁期岩浆岩的继承,震荡岩浆环带的负εHf值（-39.5~-2.86）指示源区的主要成分为古老的地壳物质,有少量地幔物质的混染。全岩锆石饱和温度（737~913°C）显示岩浆组成中有幔源物质的贡献。     

皖南祁门地区东源钨钼矿区花岗闪长斑岩SHRIMP 锆石U-Pb年龄和Hf同位素特征

江家等系列花岗闪长斑岩是皖南祁门县东源钨钼矿区含矿岩体的组成部分,位于东源花岗闪长岩的西侧。对江家和方村花岗闪长斑岩进行的SHRIMP锆石U-Pb测年结果表明,江家、方村花岗闪长斑岩的结晶年龄为149~152Ma,与富钨的东源花岗闪长岩相近。岩石地球化学和锆石Hf同位素分析显示,江家等系列花岗闪长斑岩源区具有复杂的多成分端元,其中老锆石核的正εHf值反映了成岩岩浆对晋宁期岩浆岩的继承,震荡岩浆环带的负εHf值(-39.5~-2.86)指示源区的主要成分为古老的地壳物质,有少量地幔物质的混染。全岩锆石饱和温度(737~913°C)显示岩浆组成中有幔源物质的贡献。     

豫西地区秦岭造山带武当群Nd-Hf同位素组成及其物源特征

武当群变质沉积-火山岩组合是南秦岭地体中重要的基底岩石,其形成时代和地球化学特征可以为理解秦岭造山带的构造演化提供重要的证据.本文报道豫西地区武当群上部沉积岩和下部中-酸性火山岩Sm-Nd同位素和锆石Lu-Hf同位素组成,探讨火山岩成因和沉积岩物源的同位素特征.上部沉积岩的碎屑锆石初始ε_(Hf)值变化在-30～+10之间,对应的模式年龄值t_(DM2)在1.0Ga至3.2Ga之间,初始ε_(Nd)值在-4.0至-6.0之间.沉积物源表现为主要与扬子陆块有亲缘关系的地壳物质和近源的下部火山岩混合的特征.火山岩的锆石初始εHf值变化在-35～+15之间,对应的模式年龄值t_(DM2)在0.8Ga至3.5Ga之间,集中于1.5～1.8Ga和2.2～2.4Ga两个峰值.2个变质石英角斑岩样品初始ε_(Nd)值分别为-9.2和-10.7,而报道的湖北武当群的玄武-安山质熔岩的初始ε_(Nd)值以正值为主.因此,武当群不同类型的火山岩可能存在着成因差异.具有低初始ε_(Nd)值和ε_(Hf)值特征的火山岩可能由地壳物质的重熔而形成的;有些火山岩具有初始ε_(Hf)值变化范围较大(-35～+15)或正初始ε_(Nd)值的特点,可能是壳、幔物质混合成因,有显著的幔源或新生地壳物质的贡献.武当群Nd-Hf同位素组成和碎屑锆石年龄分布特征表明,与扬子陆块有亲缘关系的南秦岭地体在元古代期间可能经历多期地壳增生和再造作用.     

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.     

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.     

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.     

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″.