准晶格的推导与准晶体的微粒分数维结构模型

五次对称和准晶态的发现(Shechtmen,1984)不仅是结晶学的新阶段,对包括地质学在内的整个自然科学将产生深远影响(彭志忠,1985)。在准晶体结构中,配位二十面体作长程定向有序,但无平移有序。作者(1985)探讨了准晶体的构筑原理,认为,在准晶体的结构中两个原理在起作用,即二十面体原理和黄金中值原理。     

绿泥石在三大岩中的赋存状态和成因

绿泥石广泛存在于各种岩石和地质环境中,它既是低级变质岩、热液蚀变岩中的主要矿物,也是沉积岩中的常见产物。对三大岩类中的绿泥石通过镜下薄片鉴定、扫描电镜等技术分析,显示:绿泥石族分为三八面体亚族绿泥石和二八面体亚族绿泥石。在沉积岩、火成岩和变质岩中,绿泥石的成因、化学特征、赋存状态、结构构造等各不相同。     

一种罕见的纤维状膨胀绿泥石的矿物学特征

概述绿泥石族矿物为2∶1∶1型(或2∶2型)层状结构硅酸盐矿物,类质同象置换现象很普遍,层电荷不定,分类十分复杂。其结构由似云母层(2∶1)和似水镁石层交替组成。按八面体阳离子充填情况分为二八面体型、三八面体型以及二八-三八面体型。按八面体中阳离子种类可形成不同类型的绿泥石种属。一般认为膨胀绿泥石(Swelling Chlori-     

三维构造应力场的平面处理

天然变形体结构面或构造面的中心问题是它们的力学属性,当我们研究天然变形体结构面或构造面力学性质的时候,很自然追溯到岩石变形瞬间的立体应力状态(三维)与平面应力状态(二维)。     

台湾海峡表层沉积物中黏土矿物特征及物质来源

利用X射线衍射仪,对比分析台湾海峡及周边表层沉积物的黏土矿物特征,讨论长江、福建和台湾河流对海峡黏土矿物的贡献程度。福建河流（闽江）的黏土矿物以高岭石为主（>40％）,其次是伊利石（30％）和绿泥石,不含蒙脱石;长江和浙闽泥质区的黏土矿物特征是伊利石含量最高（61％～66％）,其次是绿泥石（16％～17％）和高岭石（10％～13％）,少量蒙脱石（6％～9％）。台湾河流（浊水溪）黏土矿物组合为伊利石（>70％）和绿泥石,不含高岭石和蒙脱石为特征。台湾海峡高岭石含量由西向东明显减少,说明高岭石主要来自福建的河流。〖JP2〗台湾海峡50 m等深线以东区域的黏土矿物具有高的伊利石和绿泥石含量,低的蒙脱石和高岭石含量,且伊利石的化学指数和结晶度值都明显低于长江和福建的河流,反映台湾河流的物质来源。在台湾暖流作用下,台湾河流为台湾海峡中北部提供了大量的伊利石和绿泥石。福建近海的黏土矿物主要是由福建河流提供的,但在平潭岛周边海域的黏土矿物可能有长江物质的混合。〖JP〗     

平缓褶皱的趋势面分析举例

趋势面分析应用于构造地质学已有十几年的历史。本文除一般沿用前人的分析方法外,在陈太源同志的启发下,对趋势面分析结果的解释采用了构造力学的理论。一、趋势面分析的数学原理趋势面分析的方法较多,常用的有两种:一是多项式趋势面分析,一是富里叶趋势面(又称调和趋势面)分析。     

滇西北羊拉铜矿床绿泥石成因矿物学

位于三江特提斯成矿域的羊拉铜矿是一个典型的矽卡岩型矿床。羊拉铜矿床从侵入体到围岩发育一系列蚀变作用,且具有明显的蚀变分带特征。然而,前人对羊拉矿床蚀变矿物的研究主要集中于石榴子石等干矽卡岩阶段的矿物,对区内广泛发育的绿泥石等退化蚀变阶段矿物缺乏系统的矿物学及成分的研究,制约了对该矿床成矿过程的全面认识。为此,本文以羊拉铜矿床矽卡岩型矿化中的绿泥石为研究对象,利用电子探针(EPMA)以及激光剥蚀电感耦合等离子体(LA-ICP-MS)原位微区技术开展了成分分析。结果表明：1)羊拉铜矿床绿泥石可分为早晚2期,早期绿泥石(Chl-Ⅰ)与钙铁榴石及黄铜矿等硫化物共生,晚期绿泥石(Chl-Ⅱ)常与大量方解石共生,2类绿泥石均属于三八面体结构富Mg型绿泥石,指示其形成于较为还原的环境。其Fe²⁺、Mg²⁺替代及Tschermark替代机制是2类绿泥石主量元素的主要替代机制;2)绿泥石地质温度计计算结果在140～281℃,平均224℃,2类绿泥石温度从Chl-Ⅰ→Chl-Ⅱ逐渐降低,指示该成矿作用阶段属于中-低温热液蚀变范围;3)与矿化相关的早成矿阶段(Ch...     

锌叶绿泥石矿物学研究

绿泥石类矿物是含水的镁、铁、铝层状硅酸盐,矿物结构由似云母层和似水镁石层交替沿C轴堆砌组成。按八面体空穴填充情况分为三八面体和二八面体两类,根据八面体中的阳离子种类不同可形成多种绿泥石矿物,由于四面体中硅被铝置换程度差异又可分为若干亚种。 1973年我们研究鄂北杨家堡下寒武统黑色页岩中的钒矿床时,发现一种绿色粘土矿物,当时定为镍锌绿泥石,后来发现其结构不同于普通绿泥石。进一步研究做了一些工作,今将结果综合     

研究矿物中气液包裹体的问题

研究气液包裹体有三个基本前提:(1)包裹体形成时,其内函物为均匀相;(2)包裹体形成后,其体积无明显变化;(3)包裹体封闭后,没有物质的加入和逸出。在这些前提下,才能利用包裹体的研究资料,来探讨矿物形成的物理化学条件。缺此,就失去研究包裹体的意义。因为只有在矿物形成过程中,封闭在其中的包裹体,才保存了原始矿液。所以在研究包裹体时,首先要认出那些包裹体是在矿物形成时形成的,那些是在矿物形成后形成的。前者称为原生包裹体,后者称为次生包裹体。     

一种罕见的纤维状膨胀绿泥石的矿物学特征

概 述 绿泥石族矿物为2:1:1型(或2:2型)层状结构硅酸盐矿物,类质同象置换现象很普遍,层电荷不定,分类十分复杂。其结构由似云母层(2:1)和似水镁石层交替组成。按八面体阳离子充填情况分为二八面体型、三八面体型以及二八-三八面体型。按八面体中阳离子种类可形成不同类型的绿泥石种属。     

The formation of high temperature clay minerals from basalt alteration during hydrothermal discharge on the East Pacific Rise axis at 21°N

Aluminous, high-temperature clay minerals form from alteration of tholeiitic basaltic glass and calcic plagioclase during hydrothermal venting on the crest of the East Pacific Rise at 21°N. The clay alteration assemblages are layered crusts (up to 1 mm thick) completely replacing glass and calcic plagioclase adjacent to surfaces exposed to hydrothermal fluids. The interiors of the affected basalt samples have unaltered appearances and oxygen isotopic compositions just slightly heavier than that of MORB. The surficial alteration crusts are mixtures of beidellitic smectite (aluminous, dioctahedral), randomly interstratified mixed-layer Al-rich chlorite/smectite, minor chlorite, an x-ray amorphous aluminosilicate material, and possible minor serpentine (amesite). A δ¹⁸O value of +4.1 ± 0.2%. (SMOW) is determined for the beidellitic smectite. Assuming that this smectite equilibrated with hydrothermal fluid having an oxygen isotope value between that of seawater (0%.) and 350°C hydrothermal fluid from EPR, 21°N vents (+1.6%.), an equilibration temperature between 290°C and 360°C is calculated for the beidellitic smectite. This is substantially higher than any previously reported temperature for an oceanic smectite. The mixed-layer Al-rich chlorite/smectite has a δ¹⁸O value of +3.5%., which corresponds to equilibration at 295°–360°C. The aluminous composition of the alteration assemblage is uncommon for clay minerals produced by submarine hydrothermal basalt alteration. We suggest that this assemblage is largely the product of high-temperature interaction between basalt glass + plagioclase and Mg-poor, acidic hydrothermal fluids, with possibly some contribution of Mg from bottom seawater, and that the aluminous clays either incorporate Al³⁺ remobilized from basalt by lowpH hydrothermal fluids, or are residual phases remaining after intense alteration of basaltic glass + plagioclase.     

Polysomatism,polytypism, defect microstructures,and reaction mechanisms in regularly and randomly interstratified serpentine and chlorite

High-resolution (HRTEM) and analytical electron (AEM) microscopic evidence for a polysomatic series based on regular interstratifications of serpentine (amesite) and chlorite (clinochlore) are reported from an altered skarn in Irian Jaya. The assemblage includes regular interstratifications of one clinochlore and two (2:1; three structural variants), three (3:1), and four (4:1) amesite composition 1:1 layers as well as randomly interstratified serpentine and chlorite. The order of abundance of regularly interstratified minerals is 1:1>2:1>4:1>3:1. Atomic-resolution images, image simulations, and comparison between calculated and observed diffracted intensities verify the proposed 1:1 and 2:1 structures and reveal details of their defect microstructures. AEM data show that compositions are linear combinations of the associated amesite and clinochlore. The 1:1, 2:1, 3:1, and 4:1 minerals occur both as discrete sub-micron crystals and as domains within serpentine or chlorite. Some crystals of the 2:1 phase were sufficiently large for study by X-ray precession and powder methods. Crystals of the regularly interstratified 2:1, 3:1, and 4:1 phases are usually bent. High-resolution images reveal that, within polygonal segments, the layers commonly exhibit a few degrees of curvature with segments separated by antigorite-type offsets. Deformed chlorite crystals are probably replaced by interstratified minerals during an aluminum metasomatic event. Al may have been deposited from sulfuric acid-rich solutions when they interacted with calcite and dolomite to form the anhydrite-rich corona around the phyllosilicate-rich region of the core. The interstratified chlorite (clinochlore composition) suggests aluminum addition by selective conversion of a sub-set of the chlorite layers to amesite. Defect microstructures suggest that crystals of regularly interstratified material grew by direct structural modification of preexisting chlorite. Regular interstratifications may form in response to thermally controlled limits on Al solubility in chlorite and heterogeneities in the distribution of Al-rich solutions during metasomatism. Regularly interstratified minerals coexist with randomly interstratified serpentine/chlorite, chrysotile, antigorite, lizardite, and several amesite and chlorite polytypes. Tentative chlorite and amesite identifications include one-layer (b=97°, probably IIbb), one-layer (b=90, possibly Ibb), two-, and three-layer chlorites, and 2H₁ (but possibly 1M or 1T), rhombohedral (3R or 6R), and twelve-layer (Tc; non standard) serpentine polytypes. The complex phyllosilicates attest to rampant chemical and structural disequilibrium.     

Kulkeite,a new metamorphic phyllosilicate mineral: Ordered 1∶1 chlorite/talc mixed-layer

Kulkeite occurs as platy, colorless, porphyroblastic, single crystals up to 2 mm in size in a low-grade dolomite rock associated with a Triassic meta-evaporite series at Derrag, Tell Atlas, Algeria, It is associated with sodian aluminian talc, unusual chlorite polytypes, and both K and Na phlogopite. Kulkeite is optically biaxial, negative, n _x=1.552, n _y=1.5605, n _z=1.5610, 2V_z=24° (obs.). Based on microprobe analysis the empirical formula is (Na_0.38K_0.01Ca_0.01)(Mg_8.02Al_0.99)[Al_1.43Si_6.57O₂₀](OH)₁₀ with some variation in Na, Si, and tetrahedral Al. The crystals are monoclinic with a=5.319(1), b=9.195(2), c=23.897(10) Å, β=97° 1(3)′; Z=2; the calculated density is 2.70 g cm^?3. The four strongest lines in the X-ray powder pattern are (d, I, hkl): 7.90, 100, 003; 1.533, 100, 060; 7.42, 80, 002; 3.38, 80, 007; the 001 reflection with 23.7 Å has intensity 10. Transmission electron microscopy confirms the nature of a regular 1∶1 mixed-layer, which consists of 14 Å chlorite (clinochlore) sheets alternating with sheets of one-layer (9.5 Å) talc characterized by the lattice substitution NaAl→Si just as in the talc occurring as a discrete mineral co-existing with kulkeite. Kulkeite is intergrown with lamellae of clinochlore that represent two-layer and five-layer (70 Å) polytypes with optical birefringence exceeding the normal value for clinochlore by a factor of 3. The origin of kulkeite is due to low-grade metamorphism with temperatures probably not exceeding 400° C. As the clinochlore lamellae and sodian aluminian talc are found in mutual contact, kulkeite seems to represent a metastable mineral at least during the latest phase of metamorphism. However, at an earlier stage, prior to clinochlore formation, kulkeite might have been stable, and the incorporation of Na and Al into its talc component could indeed be the decisive factor for the formation of the mixed-layer.     

Determination of Minor Contents of Smectite Layers in the Dispersed Dioctahedral K-bearing Micaceous Minerals of the Illite,Aluminoceladonite, and Glauconite Composition

A theoretically substantiated technique has been elaborated for the precise determination of minor contents of smectite layers in the dioctahedral mixed-layer structures with a disordered alternation of K-bearing micaceous and ethylene glycol-saturated smectite layers. It is shown that observed positions of the possible mixed-layer mica–smectite structures in the d(003)_obs–d(007)_obs or 2θ(003)_obs–2θ(007)_obs diagrams are distributed along a set of parallel straight lines. Data points of each straight line correspond to the mixed-layer structures with one and the same content of smectite layers. A complete matching of theoretical model was recorded in the positions of d(003)_obs–d(007)_obs and 2θ(003)_obs–2θ(007)_obs pairs of the basal reflections determined in diffractograms simulated for 160 two-component mixed-layer mica–smectite structures differing in the thickness of alternating layers and their relative content. We studied samples of the dioctahedral K-bearing micas of the glauconite, illite, and aluminoceladonite composition with different thickness of micaceous layers. Positions of the mixed-layer structures of the studied samples on the 2θ(003)_obs–2θ(007)_obs and d(003)_obs–d(007)_obs plots make it possible to visually determine the content of smectite layers in each structure accurate to 0.5%. The content of smectite layers in the studied samples varied from 2 to 15%. We obtained equations relating the thickness of smectite and micaceous layers for a specified content of smectite layers. They make it possible to determine the thickness correlation between specified mica and smectite layers. Analogous equations can be used to calculate the Wsm value in each sample for specified experimental values of d(001)_mc and d(001)_sm and d(003)_obs or d(007)_obs. The W_sm values coincide within an error limit of 0.2% with those based on the visual estimates in plots.     

珍珠石矿物的研究

珍珠石(许冀泉、方邺森,1982)曾称为珍珠陶土,它是高岭石类矿物中的一种,与地开石、高岭石、7Å多水高岭石和10Å多水高岭石同属于1:1型层状硅酸盐矿物。在高岭土的矿物组成中,珍珠石是一种罕见的矿物。目前,在我国尚未报道过珍珠石的详细矿物学数据。本文中研究的样品,通过各种方法测出的数据,初步认为它们与标准珍珠石一致。     

Crystal chemistry, thermal expansion, and Raman spectra of hydroxyl-clinohumite: implications for water in Earth’s interior

Two samples of hydroxyl-clinohumite, sample SZ0407B with approximate composition Mg_8.674(14)Fe_0.374(4)(Si_0.99(1)O₄)₄(OH)₂ and sample SZ0411B with composition Mg₉(SiO₄)₄(OH)₂, were synthesized at 12 GPa and 1,250 °C coexisting with olivine. Unit-cell parameters determined by single-crystal X-ray diffraction are given as follows: a = 4.7525(4) Å, b = 10.2935(12) Å, c = 13.7077(10) Å, α = 100.645(9)°, V = 659.04(9) Å³ for SZ0407B, and a = 4.7518(6) Å, b = 10.2861(12) Å, c = 13.7008(9) Å, α = 100.638(9)°, V = 658.15(9) Å³ for SZ0411B. Single-crystal X-ray intensity data were collected for crystal structure refinements of both samples. Relative to the pure-Mg sample, Fe decreases M3–OH bond lengths by ~0.010(3) Å, consistent with some ferric iron ordering into M3. Raman spectroscopy shows two strong bands in the lattice-mode region at 650 and 690 cm^?1 in the Fe-bearing sample, which are not observed in the pure-Mg sample. Spectra in the H₂O region show at least five bands, which are deconvolved into seven distinct O–H-stretching modes. Thermal expansion measurements were carried out for both samples from 153 to 787 K by single-crystal X-ray diffraction. The average a-, b-, c-axial and volumetric thermal expansion coefficients (10^?6 K^?1) are 10.5(1), 12.3(2), 12.5(2) and 34.9(5) for SZ0407B, respectively, and 11.1(1), 12.6(3), 13.7(3), 36.8(6) for SZ0411B, respectively. After heating, the unit-cell parameters were refined again for each sample at ambient condition, and no significant changes were observed, indicating no significant oxidation or dehydration during the experiment. For the DHMS phases along the brucite–forsterite join, linear regression gives a systematic linear decrease in expansivity with increasing density. Further, substitution of ferrous iron into these structures decreases thermal expansivity, making the Fe-bearing varieties slightly stiffer.     

四方铜金矿CuAu在我国发现

四方铜金矿产于新疆玛纳斯县清水河上游萨尔达拉含铂基性-超基性岩体中。岩体主要为暗绿色蛇纹石化斜辉辉橄岩,岩石化学成分多数为正常系列,少数为铝过饱和系列。岩体长9公里,宽140米,是一个向南倾斜的单斜岩墙。岩体侵入到泥盆系头苏泉组的黑灰色粉砂质板岩中。外接触带仅几十厘米到1米左右宽,以绿泥石化、绿帘石化、蛇纹石化为主,其次是碳酸岩化。内接触带有1米多宽,以蛇纹石化、透辉石化、透闪石化为主,个别地段有阳起石、透闪石软玉。     

Mineralogy of New Caledonian metamorphic rocks

Variations in chemistry and related physical properties of sheet silicates in the Ouégoa district with metamorphic grade are investigated. Weakly metamorphosed rocks prior to the crystallization of lawsonite contain phengite (d ₀₀₆=3.317–3.323 Å), chlorite and occasionally paragonite while interstratified basaltic sills contain chlorite, minor phengite and stilpnomelane. Pyrophyllite crystallizes before lawsonite in some metamorphosed acid tuffs and is also stable in the lawsonite zone. Paragonite, phengite and chlorite appear to be stable through the sequence from weakly metamorphosed rocks into high-grade “eclogitic” schists and gneisses. Optical, chemical and some X-ray diffraction data is given for representative sheet silicates. Electron probe analyses of 55 phengites, 21 paragonites, 57 chlorites, 12 vermiculites, 2 stilpnomelanes, and 2 chloritoids are presented in graphical form. All K-micas analysed are consistently phengitic (3.29–3.55 Si^iv ions per formula unit) and show limited solid solution with paragonite (4 to 13% Pa). The K∶Na ratio of the phengite is strongly dependant on the assemblage in which it occurs; the amount of phengite component and its Fe∶Mg ratio depends on bulk-rock composition. Phengites from acid volcanics have the highest Fe∶Mg ratio, highest phengite component and β refractive indices. Phengites from basic volcanics and metasediments of the epidote zone have the lowest Fe∶Mg ratio. Phengites from lawsonite-zone metasediments have intermediate Fe∶Mg ratios. The phengites show a small decrease in phengite component with increasing metamorphic grade. d ₀₀₆ for phengites varied from 3.302 to 3.323 Å but at least in the lawsonite and epidote zones appears to reflect composition and had little systematic variation with metamorphic grade; phengites from very low-grade rocks showed the longest values of d ₀₀₆. Paragonite shows almost no phengite-type substitution and only limited solid solution (4–12%) with muscovite. All paragonites (6) and most phengites (20) which have been examined are 2M₁ polymorphs; one Fe²⁺-phengite appears to be a 1M polymorph. The chemistry of chlorites closely reflects parent-rock chemistry. Chlorites from metasediments have distinctly higher Fe/(Fe+Mg) ratios than chlorites from basic igneous rocks; chlorites from the lawsonite and lawsonite-epidote transitional zone metasediments have the highest Fe/(Fe+Mg) ratios. In metabasalts Fe/(Fe+Mg) ratios appear to reflect individual variations in bulk-rock chemistry and show no direct correlation with metamorphic grade. There is little difference in Al/(Si+Al) ratio between chlorites from sediments and basic igneous rocks although in both lithologies the chlorites from the epidote zone appear to be slightly more aluminous. Fe-rich chlorites of the lawsonite zone metasediments have been altered by a process involving leaching of Fe and Mg and introduction of alkalies to a brown pleochroic Fe-vermiculite. Chemical and physical data for this vermiculite are given. The decrease in Fe/(Fe+Mg) ratio in chlorites and phengites on passing from the lawsonite to the epidote zone can be correlated with the crystallization of Fe-rich epidote and almandine in the epidote zone. Elemental partitioning between coexisting minerals has shown Ti to be partitioned into phengite, while Fe and Mn are strongly partitioned into chlorite. When either stilpnomelane or chloritoid coexists with phengite or chlorite, Fe and Mn are slightly enriched in the stilpnomelane or chloritoid relative to the chlorite.     

Natrolite,part II: Determination of deformation electron densities by the X-X method

A single crystal of natrolite, Na₂Al₂Si₃O₁₀ ·2H₂O (space group Fdd2), was studied by X-ray diffraction methods at room temperature. The intensities were measured in a complete sphere of reflection up to sinΘ/ λ=0.903 Å^?1. A refinement of high-order diffraction data yielded residuals of R/(F)=0.9%, R_w(F)=0.8%, GoF=1.40 for 1856 high-angle reflections (0.7≤sinΘ/ λ≤0.903 Å^?1) and R(F)=1.0%, R_w(F)=1.2%, GoF=3.07 for all 3471 independent reflections in the complete sphere of reflection. The X-X method was used to calculate deformation electron densities (DED) in natrolite. Within all tetrahedra, residual electron density-was found in the T-O bond directions indicating a considerable covalent contribution to the chemical bond. The range of the interatomic peak heights was from 0.19 to 0.34 e/ų in the SiO₄ tetrahedra and from 0.11 to 0.23 e/ų in the AlO₄ tetrahedron. The ionic contribution to the chemical bond manifests itself in the displacement of the peaks towards the oxygen atoms. Charge displacement due to interaction of nonframework cations with framework oxygen atoms as well as electron densities attributable to the lone pair orbitals in the water molecule have been observed.     

Microstructures and compositional variation in the intravolcanic bole clays from the eastern Deccan volcanic province: Palaeoenvironmental implications and duration of volcanism

Clay minerals associated with intra-volcanic bole horizons of varied colours and thicknesses contain montmorillonite, halloysite and kaolinite, show distinct microstructures and microaggregates. In kaolinite, Fe³⁺ ions substitute for Al³⁺ at octahedral sites. Most of these clays are dioctahedral type, show balance between net layer and interlayer charges. The interstratified illite — smectite (I/S) mixed layers containing variable proportions of montmorillonite. Illite contains sheet-like, well oriented microaggregates. The parallel stacks of chlorite sheets show chlorite/smectite (C/S) mixed layers. Progressive enrichment of Fe and depletion of Al ions with the advancement of kaolinization process is observed. High order of structural and compositional maturity observed in these bole clays, indicate long hiatus between the two volcanic episodes.