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171.
试验确定,在用HCI和NaOH试剂解离硅质胶结的沉积岩时,浓度5%的试剂即可达到解离度95%以上,且颗粒表面特征、重矿物数量和重矿物标型特征较浓度10%的试剂处理的样品保存得更好。 相似文献
172.
法国Echassieres地区石英网脉中黑钨矿及其共生矿物的固溶体研究 总被引:1,自引:0,他引:1
Echassiares石英网脉中的黑钨矿主要系钨锰矿一钨铁矿系列中的铁端员矿物一钨铁
矿,富泥但贫担,当其与妮铁矿共生时,钨铁矿可含8.91% Nb205。在该矿物中常见的元素置换
有:(1)Fe2+→Mn2+;(2)Wg6+Fe2+→Nb5+ +Fe+3 (3) 3W6+ +Fe2+ →4Nb5+。 妮铁矿呈它形,富含Ta. W,Ti。钨铁捉矿以枝状形态位于钨铁矿和妮铁矿之间,形成完整的矿物组合。Beauvoir花岗岩的侵位带入的热液交代钨铁矿是形成这种矿物组合的主要原因。同时,铅钨铁矿中的裂隙带或其边部还局部发生钨锰矿化。 相似文献
173.
Thomas Striebel Wolfgang Schäfer Stefan Peiffer 《Aquatic Sciences - Research Across Boundaries》1991,53(4):346-366
A field study on the geochemical properties of a chemically-stressed limnic environment was performed in Lake Silbersee, which receives leachate water of high inorganic loading from an upgradient landfill site. The highly concentrated sulfate ion in groundwater, when entering the pore water system of the lake, gives rise to an intensive microbial sulfate reduction. A diagenetic approach was used to explain the existence of a marine-like aqueous system within a geologically slightly acidic aquifer, consisting of a well-buffered lake water and an alkalinity producing, excess sulphide containing sediment pore water system. 相似文献
174.
175.
本文研究半线性椭圆方程组在Ω中以及Dirichlet边界条件u|Ω=V|Ω=0的解的存在性.其中Ω是R~n中光滑有界开集。关于非线性项f(x,u)作超线性假设。在此假设下,若f满足增长限制|f(x,u)|≤a|u|°=b,其中a、b、σ是常数.1<σ<(n+2)/(n-2),则利用临界点方法.证明了(*)+b,其中a、b、σ是常数,1<σ<(n+2)/(n-2),则利用临界点方法.证明了(*)有古典解存存。这样不用对(*)的解作先验估计,解决了Figueiredo和Mitidieri在[2]提出的问题。 相似文献
176.
本文对EDTA滴定过量Pb间接测定SO_4~(2-)的方法作了改进。加入乙醇抑制PbSO_4沉淀的溶解,使滴定不需分离沉淀而直接进行。用六次甲基四胺调节控制pH为5.2—5.4,可避免大量共存Ca~(2+)、Mg~(2+)的干扰。改进后的方法简单、快速,准确度和精密度均好,可适用SO_4~(2-)含量高于1mg/L的天然水分析。 相似文献
177.
Pressure solution is a common phenomenon in massive sulphide zinc-lead deposits of western Canada and may have been an important factor leading to the mobilization of ore-forming materials during diagenesis, deformation and metamorphism of sedimentary ores.The control of ductile shear zones over gold mineralization could be explained in view of pressure solution of gold-bearing miner-als under shearing stress and the tesultant mobilization of this metal. 相似文献
178.
软岩巷道弹塑性变形的理论分析 总被引:16,自引:0,他引:16
本文采用莫尔-库仑屈服准则和非关联塑性流动法则分析了轴对称软岩巷道的变形规律。从轴对称平面应变问题的基本方程出发,导出了软岩巷道弹塑性变形的位移理论解答,并给出了现有应力与位移理论解的适用条件。通过实例计算结果表明,本文得出的位移理论解与有限元数值解相当吻合。 相似文献
179.
This paper is concerned with the thermodynamic theory of solution and precipitation processes in wet crustal rocks and with the mechanism of steady pressure-solution slip in contact zones, such as grain-to-grain contacts, fracture surfaces, and permeable gouge layers, that are infiltrated by a mobile aqueous solution phase. A local dissipation jump condition at the phase boundary is fundamental to identifying the thermodynamic force driving the solution and precipitation process and is used here in setting up linear phenomenological relations to model near-equilibrium phase transformation kinetics. The local thermodynamic equilibrium of a stressed pure solid in contact with its melt or solution phase is governed by Gibbs's relation, which is rederived here, in a manner emphasizing its independence of constitutive assumptions for the solid while neglecting surface tension and diffusion in the solid. Fluid-infiltrated contact zones, such as those formed by rough surfaces, cannot generally be in thermodynamic equilibrium, especially during an ongoing process of pressure-solution slip, and the existing equilibrium formulations are incorrect in overlooking dissipative processes tending to eliminate fluctuations in superficial free energies due to stress concentrations near asperities, defects, or impurities. Steady pressure-solution slip is likely to exhibit a nonlinear dependence of slip rate on shear stress and effective normal stress, due to a dependence of the contact-zone state on the latter. Given that this dependence is negligible within some range, linear relations for pressure-solution slip can be derived for the limiting cases of diffusion-controlled and interface-reaction-controlled rates. A criterion for rate control by one of these mechanisms is set by the magnitude of the dimensionless quantityk/2C
pD, wherek is the interfacial transfer coefficient, is the mean diffusion path length,C
p is the solubility at pressurep, andD is the mass diffusivity. 相似文献
180.
This paper represents a systematic investigation of slope evolution diffusion models and has the following sections: (1) The model of slope development with linear coefficient k = k0x; (2) The model of slope development with quadratic coefficient in x; (3) Slope development model with vertical lowering of base level (downcutting); (4) Slope development model with the base level a horizontal variable (undercutting); (5) Steady-state regime of undercut slopes; (6) Model of a pediment and scree slope formation. The comparison is made between mathematical and classical methods of slope evolution analysis. 相似文献