O-H stretching vibrations in kaolinite,and related minerals

The grades of ordering as represented by I.R. and X-ray spectra for platy kaolinite, fire clay mineral, ball clay, dickite, nacrite and tubular dehydrated halloysite samples of various origin, are related.Well ordered kaolinite, has four bands 3,693, 3,668, 3,652 and 3,620 cm^–1. In less ordered kaolinite, fire clay mineral and ball clay these bands have shifted a little or of the middle two, which are the weakest, only one band may be left (between brackets): less ordered kaolinite: 3,695, 3,667, 3,652 (3,653) and 3,620 cm^–1; fire clay mineral 3,696, 3,668, 3,653 (3,653) and 3,621 cm^–1; ball clay 3,697, 3,652 and 3,621 cm^–1.Dehydrated halloysite has 3,693–3,698, 3,668, 3,650–3,654 and 3,620–3,626 cm^–1 bands. In the most disordered dehydrated halloysite samples (Martinsberg and Baia Mare) only two bands are left at 3,696 and 3,624 cm^–1.Dickite has four bands: 3,708, 3,656, 3,627 and 3,622 cm^–1. For the lesser ordered Mexico sample it is 3,701, 3,652, 3,627 and 3,621 cm^–1. Nacrite also has four bands i.e.: 3,700, 3,650, 3,627 and 3,620 cm^–1.There is, apart from orientation effects, a wide variation in the absolute and especially in the relative intensities of the I.R. bands and X-ray reflections for each of the mineral groups investigated here, but of various origin. The need of a nomenclature adapted to the level of our knowledge about this matter to day and comprising all these variations included those in morphology is emphasized.Quantitative analyses, the adjective meant in the sense of an accuracy of minimal 5%, constitute a difficult problem which is perhaps even wholly impossible to solve with the conventional methods of today.     

Geochemical and thermodynamic aspects of sorption of strontium on kaolinite dominated clay samples at Kalpakkam

The mobility of strontium in subsurface is largely influenced by sorption on to clay minerals. In the present study, kaolinite clay samples collected from the Kalpakkam nuclear plant site were employed to understand the sorption characteristics of strontium by batch method. The effect of several parameters such as time, strontium ion concentration, pH, temperature and ionic strength was investigated. The kinetic studies suggested pseudo-second-order mechanism. The experimental sorption data was fitted to Langmuir adsorption model for obtaining the sorption capacity of the sorbent. The maximum sorption capacity was 5.77 mg/g at 298 K and was found to increase with an increase in temperature. It was observed that the distribution coefficient (K _d) of strontium on clay increased as the pH of the solution increased. The distribution coefficient was found to decrease with an increase in concentration of Na⁺ and Ca²⁺ ions. This variation of K _d suggests that cation exchange is the predominant sorption process. It was also observed that sorption process is endothermic. The thermodynamic parameters such as ∆G ⁰, ∆H ⁰ and ∆S ⁰ were calculated. The negative values obtained for ∆G ⁰ indicated that the sorption of strontium on clay was spontaneous at all studied concentrations. ∆G ⁰ becomes more negative with an increase in temperature, suggests that the sorption process is more favorable at higher temperatures.     

Transformational changes of clay minerals, zeolites and silica minerals during diagenesis

Diagenetic transformation of clay minerals, zeolites and silica minerals in Cretaceous and Tertiary argillaceous rocks from deeply drilled wells in Japan were studied. Transformations of these minerals during diagenesis were as follows: in clay minerals, montmorillonite → montmorillonite-illite mixed-layer mineral → illite; in zeolites, volcanic glass → clinoptilolite → heulandite and/or analcite → laumontite and/or albite; in silica minerals, amorphous silica → low-cristobalite → low-quartz. Maximum overburden pressures and geothermal temperatures corresponding to these transformations in each well studied were calculated. For clay minerals, a pressure of approximately 900 kg cm^?2 and a temperature of about 100°C are necessary for the transformation from montmorillonite to mixed-layer mineral and 920 kg cm^?2 and 140°C for mixed-layer mineral to illite. Transformation from kaolinite to other minerals requires much higher pressures and temperatures than from montmorillonite to mixed-layer mineral. For zeolites, 330 kg cm^?2 and 60°C are required for the transformation from volcanic glass to clinoptilolite, 860 kg cm^?2 and 120°C for clinoptilolite to heulandite and/or analcite, and 930 kg cm^?2 and 140°C for heulandite and/or analcite to laumontite and/or albite. For silica minerals, 250 kg cm^?2 and 50°C are necessary for the transformation from amorphous silica to low-cristobalite and 660 kg cm^?2 and 70°C for low-cristobalite to low-quartz. Based on these diagenetic mineral transformations, seven mineral zones are recognized in argillaceous sediments. On the other hand, from the porosity studies of argillaceous sediments in Japan, the process of diagenesis is classified into the following three stages. The early compaction stage is marked by shallow burial and viscous rocks with more than 30% porosity. The late compaction stage is characterized by intermediate burial and plastic rocks with 30-10% porosities. The transformation stage is marked by deep burial and elastic rocks with less than 10% porosity.     

Geochemical Characteristics of the Plagiogranites in the Vicinity of Bingdaban,Central Tianshan

The tectonic and geochemical characteristics suggest that the plagiogranites exposed in the vicinity of Bingdaban on the northen margin of the central Tianshan uplift zone show a distinct mantle-source character, and their enrichment in LREE and selected enrichment in LILE(large ion lithophile elements)reflect a setting related to an arc tectonic regime.These rocks represent the products formed at shallow levels from mantle-derived magmas modified with subduction components(or super crustal rocks).     

吉林省长白县马鹿沟高岭石矿地质特征及成因

本文通过对长白县马鹿沟高岭石矿地质条件进行分析,对矿床成因进行了总结。马鹿沟高岭石矿赋存于三叠系长白组中,其成因为火山沉积-热液蚀变型,成矿物质来源于酸性凝灰岩,成矿时代为三叠纪晚世,矿体围岩主要为凝灰岩、角砾凝灰岩,且普遍发生高岭石化或地开石化。     

河南桐柏老湾花岗岩地球化学特征及成因研究

老湾花岗岩体位于老湾金矿床南侧,主要为黑云母花岗岩,对其常量元素、稀土元素、微量元素及包裹体等地球化学特征进行了研究。结果表明,岩石贫SiO2,富碱及CaO、MgO、FeO等基性组分;多数不相容元素如Li、Rb、Nb、Ta、Zr、Hf、REE等贫化;弱负Eu异常（δEu=0.6）;岩石液相离子组合为K＋-Na＋-Cl-型;成矿元素Au富集,具备为矿床形成提供成矿物质基础。其地球化学特征总体反映,该花岗岩岩石成分偏基性、岩浆分异较弱的特点,为受地幔柱热力作用、同熔下地壳而形成的型花岗岩。     

西藏错那洞淡色花岗岩地球化学特征、成岩时代及岩石成因

错那洞淡色花岗岩是西藏北喜马拉雅淡色花岗岩带的重要组成部分。通过地球化学分析揭示其具有富硅(SiO_2含量为74.20%~74.52%)、贫铁(Fe_2O_3含量为0.04%~0.20%,FeO含量为0.40%~0.58%)、贫镁(MgO含量为0.06%~0.14%)、钙碱性(σ为2.15~2.32)、强过铝质(A/CNK为1.11~1.15)的地球化学特征。稀土元素总量较低(∑REE为47.24×10~(-6)~57.59×10~(-6)),轻稀土元素富集(LREE为39.85×10~(-6)~49.23×10~(-6)),重稀土元素亏损(HREE为6.91×10~(-6)~8.68×10~(-6)),有明显负Eu异常(0.49~0.80);富集Rb、Th、U、K等大离子亲石元素,亏损Nb、Ta、Zr、Ti等高场强元素。锆石U-Pb测年结果显示,错那洞淡色花岗岩形成中新世(21 Ma),属北喜马拉雅淡色花岗岩晚阶段峰值期(24~12 Ma)产物。锆石εHf(t)值为负值,且变化较大(-3.92~-17.64),说明其岩浆源区为壳源,以变泥质岩为主,可能存在多种物质组分的混合。初始岩浆结晶温度应不超过675~702℃,构造背景为后碰撞环境,是高喜马拉雅结晶岩系在板片快速折返过程中发生减压熔融而形成的产物。     

辽宁树基沟铜锌矿床地球化学特征及成因

辽宁树基沟铜锌块状硫化物矿床产于太古宙绿岩带中,矿床形成后经历了强烈的变质和变形,变质程度达到高级角闪岩相。通过含矿岩系地球化学研究,讨论了岩浆来源、成岩构造背景及成因。研究表明,含矿岩系明显富集大离子亲石元素、轻稀土元素及活泼的不相容元素,相对亏损高场强元素和重稀土元素,具有较高的Th/Ta、Ce/Yb、La/Nb、La/Ta比值,其原始地幔标准化的微量元素蛛网图模式与典型钙碱性岛弧玄武岩模式极为相似,均呈"三隆起"的形式,原岩为一套中酸性火山-沉积岩组合,区内这套英安岩、流纹岩、安山岩-玄武岩的钙碱性火山岩组合是由同源岩浆分异所得,其形成于岛弧环境。综合矿床形成背景环境、成矿物质来源和矿床地质特征,笔者初步认为其成因类型为诺兰达型块状硫化物矿床。     

陕西双王金矿地球化学特征及其成因分析

通过对双王金矿床角砾岩地质特征、地球化学特征的综合分析,认为双王金矿具有不同的矿源深度及剥蚀深度。值得指出的是, Sb、As的变化可作为直接指标,即受剥蚀者Sb表现明显,未受剥蚀者As表现明显;在勘探中Au、Bi、As、Ag、Sb、Mo、Ba、Pb、Zn、Cu、Hg、Mn等可作为双王金矿找矿的指示元素,其中Au、Bi、As、Ag为主成矿元素,Sb、Pb、Zn、Cu为剥蚀深度指示元素,Ba、Hg、Mn、Mo为矿区围岩及地层元素。     

江西盘古山钨矿床的碲化物特征及富集成因

江西盘古山钨矿是一个钨、铋、碲均可综合利用的大型矿床,有关其碲化物的特征及成矿流体的物理化学条件研究尚属空白.文章在整理和总结前人研究成果的基础上,对矿床中碲化物开展了详细的矿相学鉴定、电子探针和流体包裹体测温.结果显示,盘古山钨矿床的碲化物主要有硫碲铋矿A、硫碲铋矿B、应硫碲铋矿、巴硫碲铋矿、硫楚碲铋矿及辉碲铋矿.矿...     

云南朱布镁铁-超镁铁岩体地球化学特征及成因机理探讨

云南朱布镁铁-超镁铁岩体赋存中型铜镍铂族元素矿床,侵位于元谋群片岩和花岗片麻岩中,岩体垂直分异明显,自下而上为橄榄岩、橄辉岩、辉石岩、辉长岩等相带.矿体以底部“边缘矿”为主,上部有呈透镜状产出的少量“上悬矿”.本文报道了朱布岩体主元素、微量元素、铂族元素(PGE)和 Sr-Nd 同位素组成新的测试结果.分析表明朱布岩体具有拉斑玄武质岩浆分异演化趋势,富集 LREE 的分布模式,弱的Nb 异常和较明显的 Sr 负异常,并与峨眉山大火成岩省(ELIP)苦橄岩相类似,暗示两者可能存在成因上的联系.朱布岩体的铂族元素相对分布模式为“Pt-Pd”富集型,原始地幔标准化曲线向左陡倾.较高的(87Sr/86Sr)i (0.7096~0.7107)和较低的εNd(t)(-3.1~-2.3),表明朱布岩浆受到了地壳物质不同程度的混染.通过岩浆演化过程反演,得出其母岩浆性质为苦橄质,并估算地壳混染程度在3%~20%之间,发现在 R (岩浆与熔离硫化物的比例)值为1000~5000时比较吻合朱布样品中硫化物的实际测定值,证实了朱布岩体可能为开放系统的岩浆房,经过多级富集过程,先熔出的硫化物从后续多期次岩浆中吸收了大量 PGE,岩浆房中同时存在堆晶和岩浆演化,分别形成了底层橄榄岩和上部的辉长岩,中间过渡为橄辉岩和辉石岩     

Paleozoic Amphibolites,Kreuzeck Mountains,Austria: Geochemical variations in the vicinity of mineralization

Strata-bound antimony, mercury, tungsten and massive sulfide mineralization occurs within a metamorphosed Paleozoic volcanosedimentary sequence in the Kreuzeck Mountains, Austria. Amphibolites are a significant constituent of that sequence; on the basis of stable trace element data, they can be classified as metamorphic equivalents of recent olivine tholeiites. In the ore environment of strata-bound mineralization, intensive alteration associated with submarine hydrothermal activity has affected the wall rocks. This includes depletion in SiO₂, a change in the oxidation stage of iron and pronounced enrichment in Na, Sr, Ba and CO₂. Microprobe analyses reveal lower MgO content in chlorites and higher Na₂O content in feldspars in rocks from the ore environment. Hydrothermal halos are thus documented by changes in mineral and whole-rock compositions and represent guides to exploration.     

北京周口店岩体地球化学特征及物源分析

通过对周口店岩体地球化学特征和构造环境及其与埃达克岩对比的分析，发现该岩体具有C型埃达克岩的地球化学特征。^143Nd／^144Nd-^87Sr／^86Sr图解发现该岩体的锶、钕同位素投影点均落在EMI型富集地幔区域内，表明其物质来源与EMI型富集地幔有关。而εNd（t）-ISr图解中，其投影点正好落在汉诺坝二辉麻粒岩包体范围内（汉诺坝二辉麻粒岩包体是幔源基性岩浆在晚古生代-中生代底侵到下地壳底部构成的年轻下地壳的一部分）。由此推测认为，周口店岩体是中生代新增生的华北克拉通下地壳的部分熔融的产物。     

云南金平铜厂Cu-Mo矿床矽卡岩地球化学特征及成因

云南金平铜厂Cu-Mo矿床位于滨太平洋与特提斯构造域结合部位哀牢山构造成矿带南端,该矿床主要由矽卡岩Cu-Mo矿体组成,其中Cu储量0.862×104 t（品位1.24%）,Mo储量1.706×104 t（品位0.21%）。为查明矿区内与成矿关系密切的矽卡岩成因及其与围岩的关系,分析其不同元素的性质及分布规律,揭示矽卡岩矿床成岩、成矿地质过程,本文通过采集铜厂Cu-Mo矿区矽卡岩及矽卡岩化正长斑岩和大理岩样品进行主微量、稀土元素地球化学分析,研究其特征。研究表明：Si、Fe、Ca、Ti、Al、Mg、Mn等主量元素在矽卡岩、正长斑岩之间曾发生明显置换交代地质作用;三种岩性都具有富集LREE元素,亏损HREE元素,发育较弱Eu负异常,Ce异常不明显,REE配分模式相似的稀土元素特征,说明矽卡岩、正长斑岩和大理岩有一定的成因联系。结合三者REE配分模式、Eu弱负异常及Ce异常不明显等地球化学特征,推测矿区矽卡岩形成于低温弱氧化环境,由来自深部热液流体与围岩接触交代形成,成岩流体主要来源于深部岩浆。     

Geochemical diversity of minerals of the pyrochlore group

A systematic and rational nomenclature of minerals of the pyrochlore group are developed based on the results obtained by processing 671 chemical analyses of pyrochlore-group minerals from carbonatite complexes, alkali rocks, and their pegmatites, granite pegmatites, and alkali and albitized granites. The proportions of Nb, Ta, and Ti are typomorphic of pyrochlore from these four types of geological environments. The paper lists pervasive characteristics of the distribution of Na and Ca, REE, Th and U, Sr and Ba, K and Cs, Pb, Sn, Sb, and Bi in the minerals. Based on the occurrence of compositions with elevated concentrations of typomorphic elements at site B in the structure of the minerals, pyrochlore subspecies are recognized: pyrochlore, Ta-pyrochlore, Ta,Ti-pyrochlore, Zr-pyrochlore, Nb-betafite, Ta-betafite, Ti-betafite, Ti-microlite, Nb,Ti-microlite, Nb-microlite, and microlite, as well as 60 geochemically significant varieties with the predominance of certain cations at site A (REE-pyrochlore, U-pyrochlore, etc.). Aspects of a rational systematics of minerals of complicated isomorphic series are discussed.     

冀北招素沟萤石矿地球化学特征及矿床成因探讨

招素沟萤石矿是冀北地区较为典型的萤石矿,矿床产于张家口组火山岩及早白垩世正长斑岩的断裂构造中,其矿体的产出严格受断裂控制.对萤石矿石及围岩的微量元素及稀土元素进行了系统分析.微量元素分析结果显示所有样品均表现出较高的Co、Cr、Cu、Ni含量,且变化较稳定,特别是Ni的含量明显偏高;U、Be、Mo含量较低,变化较大;萤...     

乍得Bongor盆地天然气地球化学特征及成因

Bongor盆地位于乍得境内的中非剪切带西北部,是中新生代重要的含油气盆地之一。笔者从Bongor盆地天然气组分组成及组分碳、氢同位素分析入手,综合运用常规有机地球化学分析方法,探讨了Bongor盆地不同构造单元天然气的成因及成熟度差异。分析认为,Bongor盆地天然气化学组成主要由烃类气体、非烃类气体和微量稀有气体组成,其中烃类气体属于生物热催化过渡带气、原油伴生气和凝析油伴生气等有机成因气,非烃气体主要包括无机成因的氮气、二氧化碳和氢气等。在天然气成因研究的基础上,笔者还开展了Bongor盆地烃类气体的组成及来源分析,包括气气对比和气源对比,研究认为,不同构造单元的烃类气体虽然组成相同,但相对含量略有差异,表明不同构造单元的天然气具有相似的母质来源：M组和P组的暗色泥页岩;但也不排除K组暗色泥页岩的生烃贡献。不同构造单元天然气烃类气体的成熟度差异较大,这是由于天然气源自不同层位烃源岩或同一层位烃源岩在不同演化阶段的生烃产物。     

Geology and genesis of the Cheremshanka silica deposit, western Transbaikal region, Russia

The geology and genesis of a large high-grade silica deposit is considered. It occurs in the form of a quartzite layer, 20–50 m thick, extending for 8 km in conformity with the host Upper Proterozoic silicate-carbonate metasedimentary rocks. The average content of SiO₂ is 99.2%. It has been established that quartzite was formed by metasomatic silicification of sandstone during metamorphism of the carbonate-silicate sequence. The rocks were silicified by infiltration acid leaching, whereas long-term refinement of quartzite was provided by diffusion in finely dispersed capillary-porous systems, where the energy of the solution-solid phase interface was important. In the course of metasomatic migration of components, Au, Ag, Pb, Zn, Fe, and other elements were removed from quartzite and formed gold-sulfide mineralization in contact zones of the quartzite body. This opens up opportunities for discovering economic Au-Ag and Pb-Zn ores in the ore field.     

Geochemical characteristics of vanadium in rocks and minerals from Ningwu district,China

Based upon a fairly large body of data available on vanadium in rocks and minerals from the Ningwu district of China, the distribution patterns of vanadium have been substantiated in igneous and terrestrial volcanic rocks. Also discussed are geochemical behaviors of vanadium and favorable conditions for mineralization of this element during different geological processes.     

云南大坪金矿区煌斑岩的地球化学特征及成因探讨

大坪金矿区闪长岩体中发育多条煌斑岩脉,并且多伴随石英脉出现。在岩石化学组成上,SiO2含量为44.86%~54.10%、K2O/Na2O在0.56~2.09之间,属钾玄质系列;岩石富集大离子亲石元素(Sr、U、Rb和Ba)和轻稀土元素(LREE)、相对亏损高场强元素(Ta、Nb和Ti),且Ta、Nb和Ti具"TNT"负异常;δEu值为0.72~1.36,负Eu异常不明显;87Sr/86Sr值范围为0.706 6~0.707 4,均值0.707 1,高于原始地幔现代值0.704 5;143Nd/144Nd值范围为0.512 4~0.512 5,均值0.512 4,低于原始地幔现代值0.512 638;εNd值范围为-2.5~-4.2,均值-3.98。Nb/Ta比值为48.96~82.58(平均62.99),远高于原始地幔值的17.5±2.0;Zr/Hf比值为20.45~47.53(平均39.57),略高于原始地幔值的36.27±2.0;Nb/Ta和Zr/Hf都远大于陆壳值11和33。表明煌斑岩源区可能来自早期俯冲洋壳或造山带根部拆沉组分脱水形成富集流体在地幔源区发生交代作用形成的富集地幔,岩浆在上升侵位过程中受到地壳物质的混染较弱,形成于碰撞后的板内构造环境。