An Internally Consistent Thermodynamic Model for the System CaO-MgO-Al2O3-SiO2 Derived Primarily from Phase Equilibrium Data

An internally consistent thermodynamic model for the subsolidus system CaO-MgO-Al2O3-SiO2 (CMAS) was developed and refined using primarily data from phase equilibrium experiments. The solution properties of pyroxenes and garnet were approximated with an ionic model, with independent mixing on adjacent crystallographic sites. This approach simplified the calculation of phase relations by allowing sequential calculation of the site occupancies. Enthalpy, entropy, and volume differences, nominally at 970 K, were derived for all participating phases by matching as closely as possible the experimentally observed phase relations. Although thermochemical measurements were not used directly in the refinement, the results were continuously monitored and compared with the thermochemical data to achieve a close match. The new model can be used to calculate phase diagrams for the CMAS system and its subsystems in the whole pressure range of the upper mantle. Simple empirical corrections for the effects of Na, Fe, Cr, etc., could potentially be introduced to make the model applicable to the thermobarometry of chemically complex mantle materials. Application of the new model to garnet lherzolite xenoliths from northern Lesotho and garnet peridotites from Norway supports the proposals for higher temperatures of the continental lithosphere.     

Thermodynamic Mixing Properties of Muscovite-Paragonite Crystalline Solutions at High Temperatures and Pressures, and their Geological Applications

Reversed Na-K exchange data between mica and a 2 molal aqueous(Na,K)Cl fluid (Flux & Chatterjee, 1986) have been employedto model the thermodynamic mixing behaviour of muscovite-paragonitecrystalline solutions on the basis of the Redlich-Kister equation.For these binary micas, G^ex_m may be expressed as where A=11222+1.389 T+0.2359 P, B=–1134+6.806 T–0.0840 P, and C=–7305+9.043 T, with T in K, P in b, G^ex_m, A, B, and C in joules/mol. G_m^ex is well constrained between 450 and 620?C, and may be extrapolatedbeyond that range with caution. The calculated solvi are skewedtoward the paragonite end member. In the range up to 15 kb,the critical temperature, T_c and the critical composition, X_cmay be expressed as a function of P by the relations: and with P indicated in bars. Calculated phase relations of muscovite-paragonite crystallinesolutions have been depicted in terms of the system KAlSi₃O₈-NaAlSi₃O₈-Al₂O₃-SiO₂-H₂O.These data may be applied to appropriate assemblages involvingmica, alkali feldspar, an Al₂ polymorph, and quartz to estimateP, T and a_H2O conditions of their equilibration. In principle,the muscovite limb of the solvus may be used to obtain geothermometricdata for coexisting muscovite-paragonite pairs, provided theequilibrium pressure is independently known. However, such applicationmust be restricted for the present to micas on the ideal muscovite-paragonitejoin. Mica-alkali feldspar-Al₂SiO₅-quartz or mica-plagioclase-Al₂SiO₅-quartzassemblages may be used to deduce a_H2O in the coexisting fluid,if P, and T of equilibrium are independently known. Examplesof such geological applications are given.     

ISORROPIA: A New Thermodynamic Equilibrium Model for Multiphase Multicomponent Inorganic Aerosols

A computationally efficient and rigorous thermodynamic model that predicts the physical state and composition of inorganic atmospheric aerosol is presented. One of the main features of the model is the implementation of mutual deliquescence of multicomponent salt particles, which lowers the deliquescence point of the aerosol phase.The model is used to examine the behavior of four types of tropospheric aerosol (marine, urban, remote continental and non-urban continental), and the results are compared with the predictions of two other models currently in use. The results of all three models were generally in good agreement. Differences were found primarily in the mutual deliquescence humidity regions, where the new model predicted the existence of water, and the other two did not. Differences in the behavior (speciation and water absorbing properties) between the aerosol types are pointed out. The new model also needed considerably less CPU time, and always shows stability and robust convergence.     

Adsorption of Fe~(3+) Ions from Aqueous Solution by Natural and Synthetic Apatites: Kinetic,Equilibrium and Thermodynamic Study

In this study, the adsorption kinetics, equilibrium and thermodynamics of Fe3+ ions on natural (NAP) and synthetic (HAP) apaties were examined. The adsorption efficiency of Fe3+ onto the NAP and HAP was increased with increasing temperature. The kinetics of adsorption of Fe3+ ions was discussed using three kinetic models, the pseudo-first-order, the pseudo-second-order and the intra-particle diffusion model. The experimental data fitted very well the pseudo-second-order kinetic model. The initial sorption rate and the activation energy were also calculated. The activation energy of the sorption was calculated as 37.15 and 49.84 kJ·mol 1 for NAP and HAP, respectively. Experimental results were also analysed by the Langmuir, Freundlich and Dubinin–Redushkevich (D–R) isotherm equations at different temperatures. RL separation factor for Langmuir and the n value for Freundlich isotherm show that Fe3+ ions are favorably adsorbed by NAP and HAP. Various thermodynamic parameters such as enthalpy (ΔH), Gibbs free energy (ΔG) and entropy (ΔS) changes were computed and the results showed that the adsorption of Fe3+ ions onto NAP and HAP were spontaneous and endothermic in nature.     

pH值对混合溶液中矿物溶解／沉淀的影响

以粉煤灰浸出液与自来水混合为例,结合水文地球化学模拟,分析了在混合作用下,pH值对单相混合溶液中矿物溶解／沉淀作用的影响。结果表明,由于混合作用,溶液pH值发生改变引起CO3^2-活度变化,从而影响方解石和白云石的饱和指数,随着混合比例从0．1到0．9的增加,实验和模拟单相混合溶液中白云石和方解石的饱和指数呈现不同规律的下降;在混合溶液pH值的影响下,玉髓饱和指数随混合比例的增大,呈现先上升后下降的变化趋势。     

基于实测资料对日蒸散发估算模型的比较

利用设置于江西省南昌县的新型高精度自动蒸渗仪,于2007年9月1日至2008年8月31日的实测陆面实际蒸散发过程,检验了面蒸散发互补关系模型CRAE (Complementary Relationship Areal Evapotranspiration)、GG模型 (Granger-Gray)、平流-干旱模型AA (Advection-Aridity)3个逐日路面实际蒸散发模型在不同时间尺度上的计算精度,并对计算误差的影响因素进行了讨论.结果表明:该地区实测年蒸散发量为746.1 mm,采用各模型的推荐经验参数对该地区蒸散发的估算结果误差较大,普遍干旱条件下蒸散发的计算值比观测值偏小,而湿润条件下的计算值偏大.通过对各模型的经验参数进行调整,各模型对年蒸散发量的计算精度大为提高,但逐日蒸散发过程的计算精度改进效果有限,在7日的时间尺度上,计算结果显著优于逐日的计算结果,在此时间尺度下,AA模型仍存在一定的系统误差,CRAE模型的估算精度相对较差,GG模型的总体计算效果相对最好.根据与蒸渗仪观测结果的对比分析,根据区域特征进行参数调整后的模型,需要在7日及更长时间尺度上,蒸散发模型的估算结果较为可靠.上述研究对全面认识陆面实际蒸散发特征、理解各蒸散发模型在不同时间尺度上的模拟能力、正确认识气候变化条件下的水循环特征具有重要意义.     

基于数字近景摄影测量的岩体结构面几何信息解算模型

为了快速、全面地获取岩体随机结构面信息而提高稳定性评价工作,在数字近景摄影测量测取结构面空间坐标的基础上,应用立体几何、方位概念和投影变换理论,提出并建立了基于空间坐标的结构面迹线三维模型、任一投影展示面的迹线二维模型和详细判据的产状解算模型。迹线三维模型数据更加详实展示迹线分布状况,迹线二维模型数据又能获得任一重要投影面的迹线信息并突显迹线物理意义;应用误差理论,探讨了基于数字近景摄影测量的产状解算模型获取产状的精度。实验表明,在数字近景摄影测量建立边坡三维模型点位测量精度≤2 cm时,能够解决近似线状结构面的产状获取问题。因此,岩体结构面几何信息解算模型与数字近景摄影测量相结合,可采集到更为全面的结构面几何信息并用于岩体稳定性评价。     

互相关系数自约束的重力三维反演与高效求解

本文将拟合残差计算所得的互相关系数作为先验信息,与深度加权函数同时引入到重力正则化反演的模型约束中,以提升反演结果的可靠性。针对三维反演中的大型线性方程组问题,引入阻尼LSQR （最小二乘QR分解）算法,结合等效几何格架技术,将大矩阵按照模型单元划分为若干个子矩阵进行存储与运算。理论模型计算结果表明：同时利用互相关系数和深度加权的模型自约束反演,能较清晰地反映真实异常体;基于分块矩阵的阻尼LSQR算法求解线性方程组较直接法节省了几千甚至上万倍的存储量,且计算速率提高了数倍,可在普通计算机上实现较大规模的反演计算。将其应用于云南芦子园铁铅锌铜多金属矿床隐伏花岗岩体定位,取得了良好的效果。     

The Two-Phase Region and Excess Mixing Properties of Paragonite-Muscovite Crystalline Solutions

The chemical compositions of synthetic paragonite-muscovitepairs were obtained by electron probe microanalysis of run productsprepared hydrothermally at 300, 400, 500, and 600 ?C and 2.07kbar. The microcrystalline run products were dispersed on polishedberyllium rods, and Na, K, and Si were determined simultaneously.Compositions were determined from K/Si and Na/Si ratios referredto standards. Tentative excess thermodynamic mixing properties of paragonite-muscovitecrystalline solutions, based on the two-phase composition dataand on X-ray diffraction data, are represented by the followingthird-order Margules formulation: which leads to a critical temperature of 833 ?C and a criticalcomposition of 39.0 mole per cent Mu at 2.07 kbar (the criticalphase is probably metastable with respect to alkali feldsparand corundum). These results are quantitatively in agreementwith Iiyama's (1964) ion-exchange data. From relationships amongthe quantities (arctanh s)/s, In r², and 1/T we obtain criticalconditions which are in good agreement with the above (T_c =829 ?C, N_2c = 0.396). The critical curve obtained from the aboveMargules parameters is given by: T_c(?C) = 768.8 + 31.00P(kbar). The above results are complicated by polymorphism and by possiblelack of complete equilibrium between the two-mica synthesisproducts and possible substitution of hydronium for alkalies.We emphasize, therefore, that the phase diagrams and derivedmixing properties should be applied with caution to naturalmuscovite- and paragonite-bearing assemblages.     

加筋土边坡稳定性分析的水平条分法

加筋土是一种新型的经济可靠的边坡加固方式。针对新型加筋土边坡带来的问题和基于垂直条块划分的极限平衡方法的不足,提出了一种严格满足力与力矩的平衡的极限平衡分析方法。基于水平条块的严格条分法将滑体水平的划分成若干条块,边坡中的加筋材料产生的抗力作为附加外力作用于条块上,再应用极限平衡的思想和假设对典型条块的受力状态进行分析。根据极限平衡条件推导了边坡安全系数的隐式表达式,再通过力矩的平衡,求解条间力待定系数,进而叠代求解安全系数。说明了利用本文公式计算坡顶极限承载力的方法。该方法计算结果较经典极限平衡法结果稍大。     

含钾水盐体系介稳相关系研究

针对西藏扎布耶盐湖卤水组成,采用等温蒸发法分别研究了含钾四元体系Na+,K+//Cl-,B4O27--H2O308.15K、五元体系K+//Cl-,CO23-,SO42-,B4O72--H2O273.15K下的介稳相关系。分别测定了上述体系308.15K、273.15K时介稳平衡液相组成及密度、pH值。根据实验数据绘制了相应的介稳相图、水图。结果表明,本文研究的两个体系均为简单共饱型,无复盐和固溶体生成。其中,四元体系介稳相图由2个共饱点,5条单变量曲线,4个结晶区组成。平衡固相分别为Na2B4O7.10H2O、K2B4O7.4H2O、NaCl和KCl。对比四元体系308.15K和273.15K下的介稳相图发现,平衡固相盐的种类及结晶形式均没有发生变化,但结晶区大小产生变化:在308.15K下,Na2B4O7.10H2O结晶区变小,K2B4O7.4H2O结晶区变大。五元体系投影图中有1个共饱点、3条单变量曲线和3个结晶相区。结晶相区分别为K2CO3.3/2H2O、K2SO4和KCl。K2CO3.3/2H2O结晶区面积最小,K2SO4结晶区面积最大。K2CO3对KCl有较强的盐析作用。     

On the Direction and Magnitude of Oxygen Isotope Fractionation Between Calcite and Aragonite at Thermodynamic Equilibrium

Oxygen isotope fractionation factors between calcium carbonates and water have been applied to ancient marine geochemistry principally for the purpose of geothermometry. The problem was encountered, however, with respect to the direction and magnitude of oxygen isotope fractionation between calcite and aragonite at thermodynamic equilibrium. This basically involves sound understanding of both thermodynamics and kinetics of oxygen isotope fractionation between inorganically precipitated carbonate and water at low temperatures. Thus the crucial issues are to acknowledge the processes of chemical reaction and isotopic exchange during precipitation of CaCO₃ minerals in solution, the kinetic mechanism of isotope equilibrium or disequilibrium, the effect of polymorphic transition from metastable aragonite to stable calcite under hydrous or anhydrous conditions, and the presence or absence of isotope salt effect on oxygen isotope exchange between carbonate and water in response to the hydrous or anhydrous conditions at thermodynamic equilibrium. Because good agreements exist in carbonate–water oxygen isotope fractionation factors between theoretical calculations and experimental determinations, it is encouraging to applying the thermodynamic and kinetic data to isotopic paleothermometry and geochemical tracing.     

Semivariogram Models Based on Geometric Offsets

Kriging-based geostatistical models require a semivariogram model. Next to the initial decision of stationarity, the choice of an appropriate semivariogram model is the most important decision in a geostatistical study. Common practice consists of fitting experimental semivariograms with a nested combination of proven models such as the spherical, exponential, and Gaussian models. These models work well in most cases; however, there are some shapes found in practice that are difficult to fit. We introduce a family of semivariogram models that are based on geometric shapes, analogous to the spherical semivariogram, that are known to be conditional negative definite and provide additional flexibility to fit semivariograms encountered in practice. A methodology to calculate the associated geometric shapes to match semivariograms defined in any number of directions is presented. Greater flexibility is available through the application of these geometric semivariogram models.     

基于数据仓库的数据挖掘技术

从数据挖掘的产生出发，到发展的各个分支，讨论了各种数据挖掘方法的特点和应用对象。介绍典型的算法、它们的优化改进和变形，并分析数据挖掘技术将来面临的问题及发展方向。     

Nepheline--Alkali Feldspar Equilibria: I. Experimental Data and Thermodynamic Calculations

Nepheline-alkali feldspar equilibria with alkali chloride aqueoussolutions have been determined for the temperature range 400to 700 °C at 1000 bars pressure. Nepheline-alkali feldsparequilibria with alkali chloride melts have been determined forthe temperature range 800 to 1100 °C at approximately 6bars pressure. (1) NaAlSiO₄ + KCl(aq) = NaCl(aq) + KAlSiO₄ (2) NaAlSiO₄ + KCl(melt) = NaCl(melt) + KAlSiO₄ (3) NaAlSi₃O₈(high) + KCl(aq) = NaCl(aq) + KAlSi₃O₈(San) (4) NaAlSi₃O₈(low) + KCl(aq) = NaCl(aq) + KAlSi₃O₈(Mic) (5) NaAlSi₃O₈(high) + KCl(melt) = NaCl(melt) + KAlSi₃O₄(San) (6) NaAlSi₃O₈(low) + KCl(melt) = NaCl(melt) + KAlSi₃O₈(Mic) From these, two diagrams of phase relationships were derivedfor the following exchange equilibria: (7) NaAlSiO₄ + KAlSi₃O₈(San) = NaAlSi₃O₈(high) + KAlSiO₄; (8) NaAlSiO₄ + KAlSi₃O₈(Mic) = NaAlSi₃O₈(low) + KAlSiO₄. The effect of pressure on these equilibria has been determinedby comparing the experimental data for 1000 and 5000 bars (t= 500 °C) and thermodynamic calculations. It has also beenshown that the effect of excess silica in nepheline solid solutionon the K—Na distribution between nepheline and alkalifeldspar is substantial and opposite to that of temperature.In the high temperature region an increase in silica contentin nepheline of 2 wt. per cent eliminates the effect on theredistribution of a temperature increase of 100 °C. Thesecation exchange data and unit cell data for the crystal phasesare used to calculate thermodynamic mixing properties of nephelinesolid solution and alkali feldspar solid solution for a widerange of temperature and pressure.     

三维GIS模型技术问题探讨

探讨了由二维GIS扩展到三维GIS的必要性及可行性,讨论了矿山、地质工作中对三维GIS工具的基本要求,分析了三维GIS工具研制中必须解决的技术难点,讨论了三维GIS的数据结构,以及矢量结构的三维GIS与三维拓扑关系。