The interactions between andesine grains (0.25―0.45 mm) and NaCl and KCl+NaCl solutions were experimentally studied under flow-through conditions (flow rates of solution: 7 ml/h and 1 ml/h) at 300oC and 50 MPa. For comparison, corresponding static runs were performed at the same pressure and temperature. All of these experiments were carried out in a flexible gold cell hydrothermal apparatus. The emphasis of the present study was laid on the changes in the composition of solid surface and solution chemistry at the early stage of the interaction. After the reaction an appreciable amount of etch pits and crystallites of alkali-rich feldspar appeared on the surface of the andesine. The statistical treatment of the SEM/EDAX data for the surface of the mineral reacted showed an increase in the atomic ratio of Si/Al, (K+Na)/Ca and (K+Na)/Al and a decrease in the ratio of Ca/Al, compared with the starting andesine. During the interactions, pH of solutions increased and considerable amounts of Si and Ca were transferred into the aqueous phase. In the NaCl solution experiment at a flow rate of 7 ml/h, the variations of the Si, Al, Ca and K concentration with time were very distinct. The static or "low" flow rate (1 ml/h) reaction conditions and the presence of KCl in solution seemed to hinder the release of Si in andesine to aqueous solution. It is concluded that alkali-metasomatism of andesine at flow-through condition involves the dissolution of the mineral, and the formation of alkali-rich feldspar.

The carboxylate (formate, acetate, propionate and oxalate) and common inorganic anions (F-, Cl- and SO2-4) compositions for aqueous fluid inclusion leachates from 17 mineral samples collected from various deposits have been determined using ion chromatography in conjunction with microthermometric measurements on the fluid inclusions of their host minerals. The minerals, quartz, fluorite, barite, beryl and a fewore' minerals (wolframite, pyrite and galena), came from hydrothermal vein-type deposits in felsic igneous rocks or Archean metamorphic rocks. The results indicate that short-chain carboxylates are common components in hydrothermal fluids and can be present in considerable amounts. Formic acid (as formate) is the dominant species over other carboxylic acids. The present study raises new questions about the origin and geochemical significance of carboxylates in hydrothermal ore-forming processes.

In order to verify the presence of residual organic matter in some S-type granites, a method used conventionally in petroleum geochemistry for isolation of kerogen was employed to separate carbonaceous material (CM) from the Xihuashan granite, Jiangxi Prov., China. Optical, XRD and SEM/EDAX analyses identified the acid-insoluble residue as mainly composed of various mineral debris, with a minor carbonaceous fraction found in the residue. LMR and micro-FTIR studies showed that the residue contained a small amount of CM, which is heterogeneous in composition and structural state. The occurrence of CM in the granite implies that this granitic magma originated from sediments and crystallized at relatively lower temperatures and high pressures. This deduction is consistent with geological and geochemical studies of the Xihuashan granite. A tentative model was suggested which connects CM in S-type granite with organic matter in sedimentary rocks. The conditions under which CM can be preserved in S-type granite are discussed. The occurrence of some heavy hydrocarbons is expected in the Xihuashan granite.

为了考察石英表面特征对金沉淀的影响，于20―200℃使不同切向的石英晶体光片与含金氯化物溶液相互作用。反应前后石英光片表面的SEM/EDAX、XPS和反光显微镜研究表明，所有实验中均发现金在石英表面沉淀。结合显露石英位错的浸蚀实验，发现沉淀的金晶体在石英表面的分不死守石英晶体中存在的线性缺陷控制。本文分析了本实验研究结果与前人工作的差异，讨论了金的沉淀机理和含金石英脉中金的不均匀分布。

The solubility of the buffer assemblage magnetite+hematite in 0.10, 1.00 and 3.00 mol/kg NaCl solutions with various pH values was determined by use of a Dickson gold cell hydrotherma1 apparatus at 300℃ and 500 bars. Activities of H+ and Cl-in the NaCl hydrothermal solution for each determination were approximated. The experimental results show that the solubility is strongly dependent on the pH of the solutions and appears to have no explicit relation to NaCl molality in acidic solutions. The correlation of the measured solubility with pH at 300℃ suggests a change in Fe speciation in solution at pH≈5.3-5.4. Treatment of the experimental data by a ridge regressions program and an iterative procedure indicates that the dominant species in solution under the run condition are FeOH+, Fe(OH)3Cl-, Fe(OH)03 and Fe(OH)-4. Gibbs free energy of formation for these species at 300℃ and 500 bars were derived: 0ΔGf,FeOH+=-250.4 kJ/mol; ΔG0f,Fe(OH)3Cl−=-644.7 kJ/mol; ΔG0f,FeOH03=-552.6 kJ/mol; and ΔG0f,FeOH-4=-652.7 kJ/mol. The Present study demonstrates that the change in acidity of hydrothermal ore-forming solutions exerts an important influence on the transport and deposition of Fe in nature.