Gallium and germanium in the metal and silicates of L- and LL-chondrites

Concentrations of Ga and Ge in the metal of 31 L-, 8 LL- and 2 H-chondrites, and in the silicates of 12 L- and LL-chondrites have been determined by spectrophotometric methods. The ranges of Ga contents in the metal of L- and LL-chondrites are 1.1–36.9 ppm and 1.0–34.1 ppm, respectively. The Ge content in the metal is positively correlated with Ga and ranges from 89.1–160 ppm, and 126–308 ppm for L- and LL-chondrites, respectively. The Ga content in the silicates of L-chondrites varies from 4.0 to 8.9 ppm.The Ga and Ge contents in the metal are clearly lower in unequilibrated than in equilibrated L- and LL-group chondrites. Unequilibrated (type 3 and 4) and equilibrated (type 5 and 6) chondrites are well separated in the plots of Ga vs Ge in the metal and the L- and LL-groups are also well resolved. The Ga and Ge in the metal are well correlated with petrologic grade. This suggests that Ga and Ge variations in the metal are related to thermal metamorphism. There is evidence of an enrichment of Ga in the metal due to shock-reheating.     

矿物——成矿与找矿

单颗粒矿物微量元素激光原位定量分析测试数据的大量积累和研究,使矿物成为矿床地球化学研究和矿床勘查的重要示踪剂。本文重点选择磁铁矿、磷灰石、石榴子石、榍石、锆石、绿泥石和绿帘石等的原位分析研究所获得的认识,介绍单颗粒矿物成分组合及变化在矿床类型划分、成矿年龄测定、氧逸度、成矿过程与物质来源、找矿与勘探等方面的应用。不同矿床类型中普遍存在的矿物,如磁铁矿、磷灰石等的微量元素含量及组合差异,提供了矿床类型识别的标志。单颗粒矿物,特别是矿石矿物和密切共生矿物如锡石、铌钽铁矿、赤铁矿、石榴子石、方解石等的原位定年,使成矿年龄的直接准确测定成为现实。矿物中变价元素,如Fe、V、Mn、Ce、Eu含量和/或比值的变化,指示了成矿过程氧逸度及其变化特点。从矿物核部向震荡环带与边部的微量元素含量或同位素组成的变化,示踪了成矿过程中流体来源或性质的变化。斑岩和矽卡岩矿床中与成矿作用关系密切的蚀变矿物,如绿泥石、绿帘石的形成温度、特征微量元素比值,如Ti/Sr、Ti/Co、V/Ni、Mg/Sr等,与距矿床中心距离呈线性函数关系,可定量预测距矿床中心的距离,使以绿泥石、绿帘石为代表的找矿指示矿物研究迅速发展。     

Prograde destruction and formation of monazite and allanite during contact and regional metamorphism of pelites: petrology and geochronology

The conditions at which monazite and allanite were produced and destroyed during prograde metamorphism of pelitic rocks were determined in a Buchan and a Barrovian regional terrain and in a contact aureole, all from northern New England, USA. Pelites from the chlorite zone of each area contain monazite that has an inclusion-free core surrounded by a highly irregular, inclusion-rich rim. Textures and ²⁰⁸Pb/²³²Th dates of these monazites in the Buchan terrain, obtained by ion microprobe, suggest that they are composite grains with detrital cores and very low-grade metamorphic overgrowths. At exactly the biotite isograd in the regional terrains, composite monazite disappears from most rocks and is replaced by euhedral metamorphic allanite. At precisely the andalusite or kyanite isograd in all three areas, allanite, in turn, disappears from most rocks and is replaced by subhedral, chemically unzoned monazite neoblasts. Allanite failed to develop at the biotite isograd in pelites with lower than normal Ca and/or Al contents, and composite monazite survived at higher grades in these rocks with modified texture, chemical composition, and Th-Pb age. Pelites with elevated Ca and/or Al contents retained allanite in the andalusite or kyanite zone. The best estimate of the time of peak metamorphism at the andalusite or kyanite isograd is the mean Th-Pb age of metamorphic monazite neoblasts that have not been affected by retrograde metamorphism: 364.3Dž.5 Ma in the Buchan terrain, 352.9NJ.9 Ma in the Barrovian terrain, and 403.4LJ.9 Ma in the contact aureole. Some metamorphic monazites from the Buchan terrain have ages partially to completely reset during an episode of retrograde metamorphism at 343.1Nj.1 Ma. Interpretation of Th-Pb ages of individual composite monazite grains is complicated by the occurrence of subgrain domains of detrital material intergrown with domains of material formed or recrystallized during prograde and retrograde metamorphism.     

卡林型-类卡林型金矿床勘查与研究回顾及展望

20世纪60年代美国西部发现超大型卡林金矿及1000余千米的成矿带,引起世界各国重视,70年代卡林金矿找矿理论传入中国,经历了找矿实践和初步研究的认识时期,中国陕西与贵州同时发现卡林型金矿线索;80年代中后期中国找矿有重大突破,勘查确定了包含40多例大、中型卡林型-类卡林型金矿床,分布于环扬子地台的“西北金三角”和“西南金三角”,典型矿床研究取得较大进展;90年代找矿勘探又上一新台阶,除继续发现一批矿床外,成功勘查出数例特大型该类矿床,对矿床成因、成矿机理、矿床类型与成矿动力学进行综合性研究;跨入新世纪仍有金矿床的不断发现,显示出中国西北、西南地区寻找卡林型-类卡林型金矿床的巨大潜力和良好前景。     

Partition of magnesium and iron between Olivine and spinel,and between pyroxene and spinel

Partition of Fe²⁺ and Mg between coexisting (Mg, Fe)₂SiO₄ spinel and (Mg, Fe)SiO₃ pyroxene was investigated at pressures 80 and 90 kbar and at temperatures 840 and 1050° C, using tetrahedral-anvil type of high pressure apparatus. Olivine-spinel solid solution equilibria in the system Mg₂SiO₄-Fe₂SiO₄ were discussed in the light of the partition reaction. Partition of Fe²⁺ and Mg in both olivine-spinel and pyroxene-spinel systems can not be regarded as that between ideal solid solutions. By applying the simple solution model for the partition of Fe²⁺ and Mg, sign of the heat of mixing was estimated to be positive for all olivine, spinel and pyroxene. Relative concentration of Fe²⁺ in spinel in the pyroxene-spinel system is likely to cause some change in the chemical composition of modified spinel () or spinel () in the transition zone of the mantle. A considerable change is also expected in the transition pressure of to ( + ) and ( + ) to .Presented at the symposium Recent Advances in the Studies of Rocks and Minerals at High Pressures and Temperatures held in Montreal, 1972. Jointly sponsored by the International Mineralogical Association and the Commission on Experimental Petrology.     

Cumulate and Cumulative Granites and Associated Rocks

Abstract. Processes that move crystals relative to melt, that is crystal fractionation, are of major importance in producing variations that are observed within cogenetic suites of granites. In low‐temperature granite suites, crystal fractionation initially involves the progressive separation of crystals residual from partial melting from that partial melt. Once separation of those crystals, or restite, has been completed, further fractionation may occur through the separation of crystals that had precipitated from the melt, the process known as fractional crystallization. High‐temperature granite magmas are largely or completely molten and elements such as Ca, Mg and Fe, and their associated minor elements, are in that case dissolved in the melt. Such magmas, particularly those that are more potassic and hence contain a higher fraction of low temperature melt, may evolve compositionally through fractional crystallization. Cumulate rocks result, comprising a framework of cumulus minerals with interstitial melt. In this process some of the melt is also displaced to form more felsic rocks. Such cumulate rocks may have distinctive chemical compositions, but that is often not the case. Distinctive features include SiC>2 contents near or below 50 % in rocks that are transitional in the field to more felsic granites, very high Cr and Ni, very low K, P, Ba, Rb and Zr, and anomalous abundances of the anorthite components Ca and Al. These rocks may also have positive Eu anomalies. Cumulate rocks do not necessarily have distinctive textures, at least as such features are understood at this time. Fractional crystallization can also involve the movement of precipitated crystals relative to melt. We refer to rocks as cumulative when formed from the fractions in which the abundance of crystals has increased. The production of cumulative granites typically occurs at more felsic melt compositions than is the case for cumulate granites, and this process may have its greatest significance in the fractional crystallization of the felsic haplogranites. Relative to felsic granites of broadly similar compositions lying on a liquid line of descent, cumulative granites contain more Ca, reflecting the addition from elsewhere of plagioclase crystals with solidus compositions. The abundances of Sr and Ba may be high to very high, and sometimes there are positive Eu anomalies. Cumulative I‐type granites may have low abundances of Y and the heavy REE, while the S‐type granites can be very distinctive with anomalously high abundances of Th and the heavy REE resulting from the concentrating of monazite. Generally, but not always, those who propose fractional crystallization as a mechanism for producing compositional variation within a suite of granites do not state whether the rocks in that particular case are thought to lie on a liquid line of descent or are cumulates/cumulative, although it is generally presumed that they were melts. Our experiences in eastern Australia have shown that the mechanism of fractional crystallization was quantitatively not as important during granite evolution as many workers would expect. However, there are some excellent examples of that process, most notably the Boggy Plain Supersuite. Overall in eastern Australia, varying degrees of separation of restite is a much more common mode of crystal fractionation, and that may also be seen to be the case for some other granite provinces if they are examined with that possibility in mind.     

Etch and intracutaneous landforms and their implications

Many landforms, major and minor, and including plains of various types, inselbergs, boulders, flared slopes, Rillen and rock basins, are initiated beneath the land surface, at the weathering front. They have evolved in various lithological settings. Most are formed by differential moisture attack, either controlled, or strongly influenced, by bedrock structure. Such forms of subsurface derivation may be differentiated into etch or subcutaneous features that were initiated at the base of the regolith, and intracutaneous forms that had their origin within the weathering zone. Although the agent or agents responsible for eroding the regolith and exposing the bedrock forms have varied in space and time, the similarity of etch and intracutaneous forms is such that their basic morphology persists regardless of the climatic regime in which they now occur. As the regolith is widely developed on the land surface, the forms initiated beneath and within it cannot be taken as climatic indicators. Indeed, like structural forms, these convergent forms represent a varied but significant azonal element in the physiographic landscape.     

Resource-based industrialization and country size: Venezuela and Trinidad and Tobago

There are scale advantages in resource-based industrialization (RBI). Trinidad and Tobago's small size meant that its RBI projects resulted in: relatively low revenue retention, heavy dependence on export markets, skilled personnel shortages and severe ‘Dutch disease’ effects. However Venezuela squandered its size advantage because its RBI strategy was over-ambitious. Instead of taking advantage of its ample scope for risk-reducing diversification, Venezuela concentrated largely on metals processing in a single location. Although it captured more backward linkage than Trinidad and Tobago it did so at high cost as a result of inefficient project execution. Worse, Venezuela's metals projects greatly exceeded its sizeable domestic demand, overtaxed its human resources and exacerbated existing distortions in the economy. Since poorly implemented RBI projects can overwhelm even a large developing economy, RBI is risky and should therefore only be pursued as part of a flexible, broadly-based diversification drive.     

红藻石和蓝藻石概念及分类归属的综述和修订

在分析和总结前人对红藻石和蓝藻石研究成果基础上,结合岩石薄片显微镜下观察实例,发现在以往碳酸盐岩颗粒分类中没有红藻石和蓝藻石的合适位置。鉴于红藻石重要的成因意义和造礁作用,有必要明确红藻石的概念和归属。珊瑚藻本身极易钙化,经生物矿化作用最终保存下来的珊瑚藻屑一直放在生物碎屑中,而红藻石是由非固着的珊瑚藻构成的钙质独立结核,因此也可以被划分到生物碎屑中。蓝藻石作为蓝细菌钙化作用的产物,同时鉴于蓝藻石的广泛存在,把钙化蓝细菌形成的核形石命名为蓝藻石,这一重要概念从提出到现在一直被使用。然而蓝绿藻概念已变更为蓝细菌,蓝藻石的形成与藻类无关,显然将其称作蓝菌石更加确切。因此,应将红藻石和蓝藻石分别归为生物碎屑和核形石当中,并用新的术语蓝菌石替代蓝藻石。其意义在于使红藻石和蓝藻石的概念及归属更为规范,并为碳酸盐岩颗粒的深入研究提供有益线索。     

毫米波测云雷达的特点及其研究现状与展望

云在大气的能量分配、辐射传输,尤其是水循环系统中有不可忽视的作用。云探测对云物理、人工影响天气、气候变化和航空航天等领域有重要意义,是大气科学研究的热点之一。尽管目前已经发展了很多种遥感设备对云进行观测(如激光雷达、卫星、云幂仪等),但这些设备无法得到高时空分辨率的云水平和垂直结构,而毫米波雷达是云三维精细结构探测的重要工具。由于毫米波雷达具有更接近小粒子尺度的短波长,因此更适合用来探测弱云,同时毫米波雷达也存在衰减严重的缺点。介绍了毫米波雷达的特点以及其探测小粒子的优势;对比分析了其与新一代多普勒天气雷达、晴空风廓线雷达的差异,得出：毫米波雷达具有高时空分辨率,能够更精确地反映云的垂直和水平结构,比普通天气雷达更适合监测云的变化。概括了国内外毫米波测云雷达的发展现状以及在云物理研究方面的情况,并展望了国内毫米波雷达未来研究的方向。     

Distribution of major and minor constituents between mica and host ultrabasic rocks,and between zoned mica and zoned spinel

Ultrabasic rocks with Niggli values for si between 26 and 100, and k between 0.6 and 1 have been chosen for the study of the distribution of 23 major and minor constituents between phlogopite and the host rock. The rocks include kimberlites, carbonatites and lamprophyres which contain abundant zoned micas and a few zoned spinels. Chemical variations in zoned mica and spinel were determined by electron probe microanalysis, and distribution coefficients for Al, Ti, Fe, Cr, Mg, Mn, and Ni were calculated between mica and spinel for the average composition of the mica and spinel, and for chemically-related and adjacent zones. The spinel changes from chromite in the centre to chromian ulvöspinel in the rim, and the mica from chromian phlogopite, through titaniferous biotite to chromium-poor phlogopite. Distribution coefficients for Cr and Fe between adjacent zones in spinel (0.8 and 0.02 for Cr; 1.1 and 3.1 for Fe) and in mica (0.4 and 0.1 for Cr; 2 and 0.3 for Fe) show more variation than the distribution coefficients between the cogenetic phlogopite and chromite (0.04 for Cr, 0.2 for Fe), and biotite and ulvöspinel (0.08 for Cr; 0.2 for Fe). It is concluded that distribution coefficients for major and minor constituents between related zones are more meaningful than those calculated from the average chemical composition of zoned minerals.The results indicate that phlogopite is the principal carrier of potassium, rubidium, aluminium, fluorine and primary water in kimberlite and carbonatite. Minor elements, such as chlorine, lithium, barium, nickel, chromium, titanium and zinc are present mainly in the mica, whereas sodium, strontium, calcium, carbon and manganese are more abundant in other minerals.     

三峡大坝—葛洲坝河段水沙变化及冲淤特性

掌握三峡和葛洲坝枢纽间河段水沙及冲淤特性的变化规律,是河段诸多工程问题研究的前提。对大量水沙地形资料进行分析,探讨泥沙起动理论在冲刷预测中的应用。长江上游水库建设及两大枢纽相继运行,河段年径流量微减,月均流量发生"削峰填谷"重分配,年输沙量大幅降低,河段水沙关系显著改变;河段累积冲淤量受极端水文条件和枢纽调度的短期和长期控制,时间上具有明显阶段性特征,空间上则表现为部分子河段的活跃性;床沙组成随枢纽运行先后发生细化和粗化;基于沙玉清起动流速公式绘制了起动临界条件曲线图,通过推算断面最大可动床沙粒径或临界流量,可为河床冲刷可能性的预判提供参考。     

西藏冈底斯带花岗岩的时空分布特征及地壳生长演化信息

花岗岩是大陆特有的重要组成部分,同时与矿产资源有密切的关系。西藏花岗岩约占西藏自治区面积的12％,其中,80％分布在冈底斯岩浆岩带。在空间上,冈底斯花岗岩带大致可以分为3个亚带：北带、中带和南带;在时间上,以印度一亚洲大陆碰撞事件为标尺,可将青藏高原构造一岩浆事件划分为碰撞前（〉65Ma）、碰撞期（65～45Ma）、后碰撞（〈45Ma）3大阶段。在这3个阶段中,冈底斯带都产生了具有各自特点的花岗岩构造一岩浆类型。冈底斯花岗岩类的形成演化与新特提斯班公湖一怒江洋及雅鲁藏布洋的形成演化,有密切的关系。因此,其岩石的Nd,Sr同位素资料,对地壳生长与演化有重要的指示意义。冈底斯南带的大部分地区的花岗岩,均具有εNd（t）（＋）值（＋1．64～＋5．21）,模式年龄tDM也很年青（〈500Ma）,具有初生（juvenile）地壳的特征。在花岗岩成因中地幔物质有重要的贡献。而冈底斯中带、北带及南带西段的花岗岩类以εNd（t）（-）值为特征（-5．3～-17．3）,模式年龄tDM有两组值1．2Ga及2．0～2．5Ga,暗示这些地区的地壳具有古元古代一中元古代基底在花岗岩成因中,地壳组分具有主要贡献。     

试论陆相层序地层学及其在油气勘探开发中的意义

根据陆相层序地层的自身特点,对其层序界线、层序级别、层序界面等特征进行了分析,并把陆相层序地层分成断陷和坳陷两种盆地层序模式。最后根据层序模式特征阐述了陆相层序地层学在油气勘探开发中的实际意义。     

铀钍的地球化学及对地壳演化和生物进化的影响

本文论述了在含挥发份和贫挥发份条件下Ｕ、Ｔｈ的迁移行为及其对地球和行星演化的影响,并阐述了造成地球独特地质演化历史的原因。提出了Ｕ、Ｔｈ在地球中的迁移模式以及该模式对地壳形成、演化的控制作用和对生物发展演化的可能影响。     

Petrographic and chemical characterization of igneous lithic clasts from mesosiderites and howardites and comparison with eucrites and diogenites

Combined petrographic, electron microprobe and instrumental neutron activation analysis (INAA) studies of igneous lithic clasts separated from mesosiderites and howardites and INAA investigation only of whole rock eucrites and diogenites have been performed to help elucidate the differentiation processes that occurred on asteroidal sized bodies. Although similar to eucrites in mineralogy and major element chemistry, trace element abundances in basaltic lithic clasts give evidence for more complex differentiation episodes than have been observed for eucrites. These complex fractionations include sequential melting and expulsion of liquid from the source region and remelting of cumulate materials, followed by a second fractional crystallization episode. Rare earth element (REE) abundances in a basaltic clast from Petersburg suggest that the source region which produced this melt was noticably different from that which produced the eucrites Pasamonte and Bereba.Pyroxenites from mesosiderites show slight enrichments in Sc and Mn when compared with average diogenites. This suggests that the pyroxenites in mesosiderites are not fragments of diogenites sensu stricto. A plagioclase clast from the Johnstown diogenite contains light REE abundances that are not in equilibrium with the pyroxene phase. This implies that some of the plagioclase in diogenites may be a foreign component not directly related to the diogenites. This component probably formed on the same parent body as the diogenites however.The characteristics which are inferred for the heat source are that it was spatially and temporally variable. This suggests that heating of the differentiated meteorite parent bodies may in part have been from outside the parent body.     

Polyculture and monoculture: Contrast and analysis

Although polyculture or interplanting is a dominant production method used by traditional cultivators in the tropics, there has been increasing emphasis on monoculture in agricultural development planning. Analysis of the economic and ecological consequences of these two cropping alternatives in a densely-populated area of eastern Nigeria suggests that a focus on monoculture as a panacea for increasing productivity and food supply is questionable. Polyculture is held to be ecologically superior to monoculture and, in the field area examined, economically more productive as well. Thus further investigation of polycultural approaches to agricultural development would appear to be warranted.     

Saturated and aromatic diterpenoids and triterpenoids in Eocene coals and mudstones from China

Several series of saturated, diaromatic, triaromatic C-ring cleaved and triaromatic diterpenoids and triterpenoids have been detected in 4 immature coal and mudstone samples. A number of these compounds appear to represent intermediates in a series of postulated pathways for progressive aromatization of biogenic diterpenoids and triterpenoids. Diagenetic pathways for the formation of tricyclic aromatic hydrocarbons from abietane and pimarane type diterpenoid precursors and for the formation of diaromatic, triaromatic C-cleaved and triaromatic hydrocarbons from β-amyrin and other triterpenoid precursors are proposed. Saturated and aromatized abietanes, pimaranes and phyllocladanes, which are the most abundant compounds in all 4 samples, indicate a predominant higher plant input which can be related to the Coniferales group but not to individual plant families. β-Amyrin and other triterpenoid-derived triaromatic and triaromatic C-ring cleaved hydrocarbons with triterpenoid structures are thought to be characteristic for angiosperms. The relative concentrations of the triaromatic and triaromatic C-ring cleaved hydrocarbons are higher in samples 9602 (mudstone) and 9603 (coal) than samples 9601 (coal) and 9604 (mudstone) indicating samples 9602 (mudstone) and 9603 (coal) contain relatively more angiosperm derived organic matter than samples 9601 (coal) and 9604 (mudstone). The distribution patterns and the relative concentrations of saturated and aromatic diterpenoids and triterpenoids thus are valuable markers for the determination of the relative contents of biological sources of organic material in geological samples.     

构造动力体制转换与成矿作用

在控制成矿过程的多种参数中，构造动力转换可能起着根本的作用，以胶东金矿床为主要实例，结合国内外有关问题，分别论述构造动力体制转换对其它成矿参数转换的制约、多重尺度的构造动力转换、构造动力体制转换所诱发的突发地质事件及伴随的成矿作用；详细列举剪切带构造中的临界转换现象，重点论述了整体构造背景下的局部转换（例如，总体挤压背景下的局部拉张、总体拉张盆地中的局部封闭）是一种常见的矿源－运输－汇聚结构。在构造动力体制转换带动下，多种成矿参数的联动转换是形成大型矿床的一种机制。     

三峡大坝—葛洲坝河段水沙变化及冲淤特性

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