Summary of phase compositions of experimental silicate melt, un-normalised analyses

The solubility of Re and Au in haplobasaltic melt has been investigated at 1673-2573 K, 0.1 MPa-2 GPa and IW-1 to +2.5, in both carbon-saturated and carbon-free systems. Results extend the existing, low pressure and temperature, dataset to more accurately predict the results of metal-silicate equilibrium at the base of a terrestrial magma ocean. Solubilities in run-product glasses were measured by laser ablation ICP-MS, which allows for the explicit assessment of contamination by metal inclusions. The Re and Au content of demonstrably contaminant-free glasses increases with temperature, and shows variation with oxygen fugacity (fO2) similar to previous results, although lower valence states for Re (1+, 2+) are suggested by the data. At 2 GPa, and Delta IW of +1.75 to +2, the metal-silicate partition coefficient for Re (DMet/Sil) is defined by the relation LogD[met/sil][Re] = 0.50(±0.022)*10**4/T(K)+3.73(±0.095) For metal-silicate equilibrium to endow Earth's mantle with the observed time-integrated chondritic Re/Os, (and hence 187Os/188Os), DMet/Sil for both elements must converge to a common value. Combined with previously measured DMet/Sil for Os, the estimated temperature at which this convergence occurs is 4500 (±900) K. At this temperature, however, the Re and Os content of the equilibrated silicate is ~100-fold too low to explain mantle abundances. In the same experiments, much lower Dmet/sil values have been determined for Au, and require the metal-silicate equilibration temperature to be <3200 K, as hotter conditions result in an excess of Au in the mantle. Thus, the large disparity in partitioning between Re or Os, and Au at core-forming temperatures argues against their mantle concentrations set solely by metal-silicate equilibrium at the base of a terrestrial magma ocean.

Geochemistry of silicate melt inclusions from ODP Holes 137-504B and 140-504B

Geochemical data from plagioclase-hosted silicate melt inclusions from Leg 140, Hole 504B diabase dikes are reported. Hand-picked plagioclase grains were heated to 1260°-1280°C to remelt the glass inclusions and to infer trapping temperatures. The samples were then polished to expose the inclusions, which were analyzed by electron and ion microprobes. Inclusion compositions are mainly in equilibrium with the host plagioclase and are more depleted in incompatible elements than the host rock. Simple crystal-liquid equilibrium calculations show that the melt inclusions could have been in equilibrium with depleted abyssal peridotite diopsides, whereas whole-rock basalt compositions generally could not have been. The melt inclusions are significantly more depleted than normal (N-type) mid-ocean-ridge basalt (MORB) and are consistent with being produced by 8%-16% incremental or open-system melting with 2% residual porosity in the peridotite source. These magmas were formed during pressure-release melting of the mantle over a range of depths between 30 and 15 km.

The grain-scale distribution and behaviour of melt and fluid in crystalline analogue systems

The production, segregation and migration of melt and aqueous fluids (henceforth called liquid) plays an important role for the transport of mass and energy within the mantle and the crust of the Earth. Many properties of large-scale liquid migration processes such as the permeability of a rock matrix or the initial segregation of newly formed liquid from the host-rock depends on the grain-scale distribution and behaviour of liquid. Although the general mechanisms of liquid distribution at the grain-scale are well understood, the influence of possibly important modifying processes such as static recrystallization, deformation, and chemical disequilibrium on the liquid distribution is not well constrained. For this thesis analogue experiments were used that allowed to investigate the interplay of these different mechanisms in-situ. In high-temperature environments where melts are produced, the grain-scale distribution in “equilibrium” is fully determined by the liquid fraction and the ratio between the solid-solid and the solid-liquid surface energy. The latter is commonly expressed as the dihedral or wetting angle between two grains and the liquid phase (Chapter 2). The interplay of this “equilibrium” liquid distribution with ongoing surface energy driven recrystallization is investigated in Chapter 4 and 5 with experiments using norcamphor plus ethanol liquid. Ethanol in contact with norcamphor forms a wetting angle of about 25°, which is similar to reported angles of rock-forming minerals in contact with silicate melt. The experiments in Chapter 4 show that previously reported disequilibrium features such as trapped liquid lenses, fully-wetted grain boundaries, and large liquid pockets can be explained by the interplay of the liquid with ongoing recrystallization. Closer inspection of dihedral angles in Chapter 5 reveals that the wetting angles are themselves modified by grain coarsening. Ongoing recrystallization constantly moves liquid-filled triple junctions, thereby altering the wetting angles dynamically as a function of the triple junction velocity. A polycrystalline aggregate will therefore always display a range of equilibrium and dynamic wetting angles at raised temperature, rather than a single wetting angle as previously thought. For the deformation experiments partially molten KNO3–LiNO3 experiments were used in addition to norcamphor–ethanol experiments (Chapter 6). Three deformation regimes were observed. At a high bulk liquid fraction >10 vol.% the aggregate deformed by compaction and granular flow. At a “moderate” liquid fraction, the aggregate deformed mainly by grain boundary sliding (GBS) that was localized into conjugate shear zones. At a low liquid fraction, the grains of the aggregate formed a supporting framework that deformed internally by crystal plastic deformation or diffusion creep. Liquid segregation was most efficient during framework deformation, while GBS lead to slow liquid segregation or even liquid dispersion in the deforming areas.

Numerical simulations of CO2 migration during charnockite genesis

Charnockite is considered to be generated either through the dehydration of granitic magma by CO2 purging or by solid-state dehydration through CO2 metasomatism during granulite facies metamorphism. To understand the extent of dehydration, CO2 migration is quantitatively modeled in silicate melt and metasomatic fluid as a function of temperature, H2O wt%, pressure, basal CO2 flux and dynamic viscosity. Numerical simulations show that CO2 advection through porous and permeable high-grade metamorphic rocks can generate dehydrated patches close to the CO2 flow path, as illustrated by the occurrences of ``incipient charnockites.'' CO2 reaction-front velocity constrained by field observations is 0.69 km/m.y., a reasonable value, which matches well with other studies. On the other hand, temperature, rate of cooling, and basal CO2 flux are the critical parameters affecting CO2 diffusion through a silicate melt. CO2 diffusion through silicate melt can only occur at temperature greater than 840 degrees C and during slow cooling (<= 3.7 x 10(-5) degrees C/yr), features that are typical of magma emplacement in the lower crust. Stalling of CO2 fluxing at similar to 840 degrees C explains why some deep-level plutons contain both hydrous and anhydrous (charnockitic) mineral assemblages. CO2 diffusion through silicate melt is virtually insensitive to pressure. Addition of CO2 basal flux facilitates episodic dehydrated melt migration by generating fracture pathways.

大别（超）包产到户铁岩和阜新火山岩铂族元素斌存规律研究

The platinum-group elements (PGE), including Os, Ir, Ru, Rh, Pt and Pd, axe strongly siderophile and chalcophile. On the basis of melting temperature, the PGE may be divided into two groups: the Ir group (IPGE, >2000°C) consisting of Os, Ir and Ru, and the Pd group (PPGE, <20GO°C) consisting of Rh, Pt and Pd. Because of their unique geochemical properties, PGE provide critical information on global-scale differentiation processes, such as core-mantle segregation, late accretionary history, and core-mantle exchange. In addition, they may be used to identify magma source regions and unravel complex petrogenetic processes including partial melting, melt percolation and metasomatism in the mantle, magma mixing and crustal contamination in magma chambers and melt crystallization.Compared with other rocks, (ultra)mafic rocks have lower REE content but higher PGE content, so PGE have advantages in studying the petrogeneses and evolution of them. In this study, we selected (ultra)mafic rocks collected in Dabie Orogen and volcanic rocks from Fuxin Region. Based on the distribution and behaviour of platinum-group elements, combined with other elements, we speculate the magma evolution and source mantle of these (ultra)mafic rocks and volcanic rocks.Many (ultra)mafic rocks are widely distributed in Dabie Region. According to their deformation and metamorphism, we classed them into three types. One is intrusive (ultra)mafic rocks, which are generally undeformed and show no or little sign of metamorphism, such as (ultra)mafic intrusions in Shacun, zhujiapu, Banzhufan, qingshan, Xiaohekou, Jiaoziyan, Renjiawan and Daoshichong. The other one is ultrahigh pressure metamorphic (ultra)mafic rocks, some of them appeared as eelogites, such as complex in Bixiling and adjacent Maowu. Another one is intense deformed and metamorphic, termed as tectonic slice, alpine-type (ultra)mafic rocks. The most representative is Raobazhai and Dahuapin. However, there are many controversies about the formation of those (ultra)mafic rocks. Here, we select typical rocks of the three types. The PGE were determined by inductively coupled plasma mass spectrometry (ICP-MS) ater NiS fire-assay and tellurium co-precipitation.The PGE tracing shows that three components are needed in the source of the cretaceous (uitra)mafic intrusions. They could be old enriched sub-continental lithospheric mantle, lower crust and depleted asthenospheric mantle. The pattern of PGE also shows the primitive magma of these intrusions underwent S saturation. According to palladium, we can conclude that the mantle enrich in PGE. Distribution of PGE in Bixiiing and Maowu (ultra)mafic rocks display they are products of magmas fractional crystallization. The (ultra)mafic rocks in Bixiiing and Maowu are controlled by various magmatic processes and the source mantle is depleted in PGE. Of interest is that the mantle produced UHP (ultra)mafic rocks are PGE-depleted, whereas the mantle of cretaceous (ultra)mafic intrusions are enrich in PGE. This couldindicate that the mantle change from PGE-enriched to PGE-depleted during120-OOMa, which in accord with the time of tectonic system change in the East China. At the same time, (ultra)mafic intrusions in cretaceous took information of deep mantle, which means the processes in deep mantle arose structural movement in the crust The character of PGE in alpine-type (ultra)mafic rocks declared that the rocks had experienced two types of metasomatic processes - hydrous melt derived from slab and silicate melt. In addition, we analyze the platinum-group elements in volcanic rocks on the northern margin of the North China Craton, Fuxin. The volcanic rocks characterized by negative anomalies of platinum. This indicates that platinum alloys, which may host some Pt resided in the mantle. The PGE patterns also show that Jianguo alkali basalts derived from asthenospheric mantle source, but wulahada high-Mg andesites derived from lithospheric mantle.

锡在流体和花岗质熔体间分配行为的实验研究

锡矿床是与花岗岩在时间、空间、成因上有着密切联系的典型矿种之一。与锡矿有关的花岗岩多具有过铝、富钾、硅含量高的特征。传统观点认为与锡矿有关的花岗岩主要是S型花岗岩，可是近年在国内外相继发现了许多具有重要经济价值的锡矿床与富碱侵入岩有着密切成因联系。与富碱侵入岩有关的锡成矿作用日益受到地质学家的重视，锡矿床与富碱侵入岩的关系已成为研究热点之一，相关的研究工作虽然取得了很大的进展，但是富碱侵入岩体能否分异出富锡成矿流体还存在争议。研究表明，与岩浆岩有关的成矿与岩浆演化过程中成矿元素在流体-熔体相间的分配行为有着密切的关系。成矿元素在流体-熔体相间的分配行为除受到温度、压力及氧逸度等物理化学条件的制约外，还受到岩浆熔体成份及岩浆分异出来的流体化学组成的影响。以往有关锡在流体-熔体相间分配行为的实验研究主要侧重于改变流体相来观测锡的分配系数，且多为单一的含氯或含氟岩浆体系，这制约了对岩浆演化过程中元素在流体-熔体相间分配行为的深入认识。本文通过改变流体相、熔体相的化学组成，开展了一系列锡在流体和花岗质熔体相间分配行为的实验研究。综合分析了锡在晶体-熔体-流体间的分配行为，并结合地质实际探讨与富碱侵入岩有关的锡成矿的物理化学条件和成矿机理。研究成果对深入认识与花岗岩有关锡矿的成矿机理、丰富和完善与花岗岩有关的锡成矿理论、为进一步探索与花岗岩有关的锡成矿规律提供重要的实验依据。此外，实验对进一步推动实验地球化学学科发展具有重要意义。 实验在中国科学院地球化学研究所矿床地球化学国家重点实验室的成矿实验室完成，主要实验设备为快速内冷（RQV）高压釜。实验的温度为850℃，压力100MPa、氧逸度接近NNO。实验首先采用人工合成硅酸盐凝胶的方法制成具有不同化学组成的花岗质熔体，使用分析纯化学试剂配制不同成分和不同浓度的溶液，分别作为实验初始固液相。主要开展了三方面的实验研究：1．熔体相组成不变，以改变流体相组成来观察锡的分配行为。这组实验固相初始物为过碱质富钾的硅酸盐，初始液相分别为NaCl、KCl、HCl、HF、去离子水溶液；2．流体相组成不变，改变熔体化学组成观察锡分配行为。初始液相选用低浓度的0.1mol/L HCl溶液，熔体相为具不同化学组成的凝胶（其中一组改变熔体碱质含量和铝饱和指数ASI、另一组改变熔体钠钾摩尔比值）；3．氟氯共存含水的花岗质岩浆体系中氟氯含量相对变化时锡分配行为。实验通过改变熔体相中氟含量和液相盐酸溶液的浓度来观察锡在含氟硅酸盐熔体和不同浓度盐酸溶液间的分配行为。氟主要以(NaF+KF)混合物的形式加入初始固相中。实验研究结果表明： 1．流体相络阴离子种类及含量对锡在流体-熔体相间的分配行为有着明显的影响。当流体相中络阴离子Cl－、F－含量增大时，有利于增大锡在流体-熔体相间的分配系数；尤其当流体为富氯的酸性流体时，锡在流体-熔体相间的分配系数随液相中HCl浓度的增大而增大并存在关系式logD Sn=2.0247×log[HCl]＋0.6717（[HCl]的单位为mol/L），锡在流体相中主要以二价锡氯配合物的形式迁移，锡倾向于分配进入富氯的酸性流体中。此外，富氯酸性流体与共存的熔体反应后，熔体中的碱质含量降低，铝饱和指数增大。 2．熔体化学组成对锡在熔体相/流体相的分配行为有着明显的影响。D Sn随着熔体中碱质含量增大而减小：D Sn=－0.0489×MAlk＋0.4516, R2=0.98（MAlk为熔体中Na2O+K2O摩尔含量），表明富碱质熔体有利于锡在熔体相中富集，从而可能为锡矿形成提供矿质来源。D Sn随熔体ASI值的增大而增大：D Sn=0.1886×ASI－0.1256, R2=0.99，即过铝质熔体相对有利于锡分配进入流体相中。过铝质熔体中碱质总量及其它组分相对不变的前提下，熔体钠钾摩尔比值越高D Sn越小：D Sn=－0.0314×RNa/K＋0.0483, R2=0.82（RNa/K为Na/K摩尔比值），富钠的熔体有利于锡分配进入熔体相，而富钾的熔体却相对有利于锡分配进入流体相中。 3．在氟氯共存花岗质岩浆体系中：①熔体相中氟含量对氯在流体-熔体相间的分配有着明显影响，熔体中氟含量降低有利于氯分配进入流体相。②熔体中氟含量大于约1 wt%后，D Sn小于0.1且变化不大，当液相富含HCl且熔体中氟含量从约1 wt%降低后，D Sn 迅速增大，即熔体中氟含量小于约1 wt%后锡倾向于分配进入富氯的酸性流体中。而富氟（F含量大于约1 wt%）的熔体有利于萃取锡并使锡在熔体相中富集。③熔体铝饱和指数ASI值越大，相应锡的分配系数越大；流体相中HCl浓度增大时，锡分配系数随之增大；当熔体为过铝质的花岗质熔体、流体富含HCl时有利于锡分配进入流体相。 分析总结与花岗岩有关的锡成矿特征和锡在不同晶体相和熔体相间的分配行为得出：壳源铝质、富碱、富挥发份、贫钙铁镁的岩浆在结晶分异演化过程中相对有利于锡在残余熔流体相中富集。因此，具有这些特征的岩浆结晶分异演化产生的晚期岩浆可富含锡，能为后期锡矿床的形成提供矿质来源。这种富锡富挥发份的岩浆在上侵过程中，当温度压力降低、岩浆水饱和度增大、硅含量增大、熔体相氟含量降低时，可分异出含氯富锡的成矿流体。 根据上述结论，分析了与湖南芙蓉锡矿床有着密切成因联系的骑田岭花岗岩的岩石化学特征、成岩成矿物理化学条件，得出芙蓉锡矿床成矿流体可由骑田岭晚期岩浆分异产生。 最后得出如下认识：1)当花岗质岩浆体系水不饱和、流体相络阴离子浓度低的情况下，锡倾向于分配进入熔体相中；2)水饱和富含挥发份的过铝、富钾的岩浆体系有利于锡分配进入流体相；3) 铝质、富钾、富挥发份的富碱侵入岩岩浆演化过程中可在有利的物理化学条件下分异出富锡的流体相，与芙蓉超大型锡矿床有成因联系的骑田岭富碱侵入岩体成岩过程中可分异出富锡的成矿流体。

花岗岩-LiF-NaF-H_2O体系液相不混溶的实验研究

Liquid segregation phenomena have been found and explained in the F(Li)-rich granites in south China by Wang Linakui et al. (1979; 1983). A number of experimental investigations into the liquid immiscibilities in the granites systems have been carried out (Anfilogov et al., 1983; Glyuk et al., 1971; Glyuk et al., 1973a; 1973b; kovalenko, 1978; Wang Liangkui et al., 1987). Nevertheless, the detailed scenarios of the liquid immiscibilities in the granitic magmas are much less understood. This experimental study is amide to get access to this problem. Starting materials are biotite granite +LiF(3-10%)+NaF(3-10%)+H_2O(30%). The experimental results have shown that the liquid immiscibilities of melts of different compositions occur at 1 kbar and 840 ℃ when 5wt% (LiF + NaF) are added to the granite samples. three kinds of glasses indicating of three types of coexisting immiscible melts have been observed: light blue matrix glass, melanocratic glass balls and leucocratic glass balls. It is interesting that we have observed various kinds of textures as follows: spherulitic texture, droplets, flow bands, swirls. All these textures can be comparable to those in the natural granitic bodies. Electron microprobe data suggest that these different kinds of glasses are of different chemical compositions respectively; matrix glasses are F-poor silicate melts; melanocratic balls correspond to F-rich silicate melts; and leucocratic balls are the melts consisting mainly of fluorides. Raman spectrometric data have indicated that different glasses have different melt structures. TFM Diagrams at 1000 * 10~5 Pa have been plotted, in which two miscible gaps are found. One of the two gaps corresponds to the immiscibility between F - poor silicate melt and F-rich silicate melt, another to that between the silicate melt and fluoride melt. The experiments at different pressures have suggested that the decreases in pressures are favorable to the liquid immiscibility. Several reversal experiments have indicated that the equilibria in different runs have been achieved. We have applied the experimental results to explain the field evidence of immiscibilities in some of granites associated with W-Sn-Nb-Ta mineralization. These field phenomena include flow structure, globular structures,mineralized globular patche and glass inclusions in topaz. We believe that the liquid immiscibility (liquid segregation) is a possible way of generation of F(Li)-rich granites. During the evolution of the granitic magmas, the contents of Li, F, H_2O and ore-forming elements in the magmas become higher and higher. The granites formed in the extensional tectonic settings commonly bear higher abundences of the above-mentioned elements. the pressures of the granitic magmas are relatively lower during the processes of their emplacements and cooling. The late-staged magmas will produce liquid immiscibilities, leading to the production of several coexisting immiscible melts with different chemical compositions. The flow of immiscible consisting magmas will produce F(Li)-rich granites. It is also considered that liquid immiscibilities are of great significance in the production of rare metal granites. The ore-forming processes and magmatic crystallization and metasomatic processes can be occur at the same time. The mineralisations of rare metals are related to both magmatic and hydrothermal processes.

Modification of Polypropylene and Polystyrene Using Nanosilica

The present work focuses on the modification of the commonly used thermoplastics, polypropylene and polystyrene using nanosilica preparcd from a cheap source of sodium silicate. Melt compounding technique has been used for nanocomposite preparation as it is simple and suited to injection moulding. Nanosilica in a polymer matrix provide significant enhancement in strength, stiffness and impact strength. Incorporation of silica particles in a polymer also improves its thennal stability. To achieve better dispersion of fillers in polymer matrices the mixing was done at different shear rates. The enhancement in material properties indicates that at higher shear rates there is greater interaction between particles and the matrix and it depends on filler concentration and type of polymer used. N anosilica is a useful filler in thennoplastic polymers and has been applied in automotive applications, electronic appliances and consumer goods.This thesis is divided into six chapters. General introduction to the topic is described in chapter 1. Salient features of polymer nanocomposites, their synthesis, properties and applications are presented. A review of relevant literature and the scope and objectives are also mentioned in this chapter.The materials used and the vanous experimental method and techniques employed in the study are described in chapter 2. Preparation of nanocomposites by melt blending using Thenno Haake Rheocord, preparation of samples, evaluation of mechanical and thennal properties using UTM, Impact testing and characterization using DMA, TGA and DSC and morphology by SEM are described.The preparation of nanosilica from a laboratory scale to a pilot plant scale is described in chapter 3. Generation of surface modified silica, evaluation of kinetic parameters of the synthesis reaction, scale up of the reactor and modeling of the reactor are also dealt with in this chapter.The modification of the commodity thennoplastic, Polypropylene using nanosilica is described in chapter 4. Preparation of PP/silica nanocomposites, evaluation of mechanical properties, thermal and crystallization characteristics, water absorption and ageing resistance studies are also presented.The modification of Polystyrene using synthesized nanosilica IS described in chapter 5. The method of preparation of PS/silica nanocomposites, evaluation of mechanical properties (static and dynamic), thermal properties melt flow characteristics using Haake Rheocord, water absorption and ageing resistance of these nanocomposites are studied.

Rheology of magmas with bimodal crystal size and shape distributions: insights from analog experiments

Magmas in volcanic conduits commonly contain microlites in association with preexisting phenocrysts, as often indicated by volcanic rock textures. In this study, we present two different experiments that inves- tigate the flow behavior of these bidisperse systems. In the first experiments, rotational rheometric methods are used to determine the rheology of monodisperse and polydisperse suspensions consisting of smaller, prolate particles (microlites) and larger, equant particles (phenocrysts) in a bubble‐free Newtonian liquid (silicate melt). Our data show that increasing the relative proportion of prolate microlites to equant pheno- crysts in a magma at constant total particle content can increase the relative viscosity by up to three orders of magnitude. Consequently, the rheological effect of particles in magmas cannot be modeled by assuming a monodisperse population of particles. We propose a new model that uses interpolated parameters based on the relative proportions of small and large particles and produces a considerably improved fit to the data than earlier models. In a second series of experiments we investigate the textures produced by shearing bimodal suspensions in gradually solidifying epoxy resin in a concentric cylinder setup. The resulting textures show the prolate particles are aligned with the flow lines and spherical particles are found in well‐organized strings, with sphere‐depleted shear bands in high‐shear regions. These observations may explain the measured variation in the shear thinning and yield stress behavior with increasing solid fraction and particle aspect ratio. The implications for magma flow are discussed, and rheological results and tex- tural observations are compared with observations on natural samples.

New constraints on the genesis and long-term stability of Os-rich alloys in the Earth's mantle

A variety of seemingly unrelated processes, such as core-mantle interaction, desulfurization, and direct precipitation from a silicate melt have been proposed to explain the formation of Ru-Os-Ir alloys (here referred to as osmiridiums) found in terrestrial mantle rocks. However, no consensus has yet been reached on how these important micrometer-sized phases form. In this paper we report the results of an experimental study on the solubilities of Ru, Os and Ir in sulfide melts (or mattes) as a function of alloy composition at 1300 degrees C. Considering the low solubilities of Ru, Os, and Ir in silicate melts, coupled with their high matte/silicate-melt partition coefficients, our results indicate that these elements concentrate initially at the ppm level in a matte phase in the mantle source region. During partial melting, the extraction of sulfur into silicate melt leads to a decrease in fS(2) that triggers the exsolution of osmiridiums from the refractory matte in the residue. The newly formed osmiridiums may persist in the terrestrial mantle for periods exceeding billions of years. (C) 2012 Elsevier Ltd. All rights reserved.