高温高压下C—O—H流体的研究

C－O－H流体是地球内部流体的主要组成部分，确定高温高压下它们的组成关系对于认识地球的演化，氧化还原环境以及促进包裹体的研究都具有重要的意义。高温高压实验确定了它们与石墨平衡存在一个间断温度，理论计算一般在此温度之上进行，当压力，温度确定时，再加上一个外部条件如fO2或H／O比值，就可以得到它们的平衡组成。由于缺乏流体组分的高温高压热力学数据，目前的理论计算结果与实验值存在差别，电解质的出现和动力学因素影响着流体组分的平衡计算，加强系统研究，在实验中尽量采用就位分析的方法，获取更多更可靠的高温高压势和学数据，加强流体平衡影响因素的研究，是今后进一步的研究方向。     

大洋中脊热水探测与新型传感器

对大洋中脊的探测带来了大量科学发现。在大洋中脊热水喷口的极端条件下，在大的温度梯度范围内，一方面在喷口（黑烟囱）周围形成巨量金属硫化物快速堆积；另一方面在喷口周围由内向外形成一个生物晕。为了研究洋中脊极端条件下的水热过程，模拟洋中脊水-岩相互作用条件下生命过程，需要在高温高压环境中原位获取数据，必须利用先进、灵敏的化学传感器。由于新材料技术的发展，美国和西方国家深海探测时广泛使用YSZ电化学传感器（氧化钇稳定的氧化锆陶瓷，YSZ：Yttria Stabilized Zirconia），这种传感器的优点是在温度大于200℃的高温时性能良好，在低于200℃条件下灵敏度降低，而且在国际市场上没有这些高温高压化学传感器出售。“十五”期间，科技部863计划，首次将发展深海高温高压传感器的海底多参数检测技术之一列入我国计划。根据863计划，中国科学家通过努力研制成功一系列具有中国自主知识产权的高温高压化学传感器，在自主研制了YSZ传感器的同时，发明了国际上首次可以在大温度范围、在海上实用的Zr／ZrO2高温化学传感器，可部分替代YSZ传感器。这两类集成式化学传感器可以探测大洋中脊400℃／40MPa热水的pH、H2、H2S、Eh等，并在2004年的南海的海试中取得成功。     

钇稳定氧化锆传感器在地学实验中的应用

在地球科学实验中,氧逸度、氢逸度是反映待测体系的氧化还原状态和制约体系发展过程的重要参数。本文阐述了钇稳定氧化锆（YSZ）的导电机理和不同稳定剂（Y2O3）掺杂量对性质的影响,并列举了实验地球化学中利用YSZ传感器测定体系氧逸度、氢逸度及pH值的方法。与已有的其他氧/氢逸度测量方法相比较,YSZ传感器在实验中有耐高温、高压、抗腐蚀性强、响应快、原位测定特性好等诸多优点。最后指出了YSZ在应用于实验过程中的存在问题。随着陶瓷制作技术、微机械加工技术和微电子技术的发展,YSZ在地学实验中的应用将更加多样化和具有针对性。     

铅锌矿床中铅锌硫化物真的是从酸性溶液中析出?--以云南会泽铅锌矿床为例

流体是不是呈酸性,不是简单地由其pH值是否小于7确定,而应该根据其pH值是否大于一定温度下纯水的pH值确定。以会泽铅锌矿床为例,根据不同成矿阶段矿物相之间的平衡条件,讨论了成矿流体pH值随温度变化的情况。结果表明,会泽铅锌矿床成矿时流体呈中性—弱碱性,金属矿物(包括金属硫化物)是从中性—弱碱性溶液(而不是酸性溶液)中析出,这与前人的观点有着很大的不同。     

开放体系下方铅矿和黄铁矿之间原电池反应的实验研究

金属硫化物矿物之间的原电池反应对于酸性矿山排水的形成、硫化物矿床的次生富集作用、地球电化学勘探以及湿法冶金过程等都有很重要的影响。通过改变溶液中氧化剂组分F e3 的浓度、pH值、溶液的流动状况以及溶液的盐度(如N a2SO4的浓度),采用精密的电流计和电位计,对作为阳极的黄铁矿与作为阴极的方铅矿所形成的原电池反应的电流密度和整个原电池的混合电位进行研究,结果表明:溶液中[F e3 ],pH值以及溶液的流动状况对黄铁矿和方铅矿之间原电池反应的影响很大,而溶液的盐度对反应的影响不是很显著。实验还发现,当黄铁矿电极表面存在微小裂纹时,其电极电位可降低至同条件下方铅矿的电极电位以下。这一实验结果在混合电位理论和Bu tler-V o lm er方程中得到了理论上的解释。     

上地幔超高压流体的金刚石压砧实验研究

地球深部流体主要是NaCl-H2O溶液,越到地球深部,它赋存的温度、压力越高,性质状态也不断变化,反之,亦然。当NaCl-H2O流体进入和脱离(上升过程)超临界状态时,其性质会发生截然不同的变化,影响着各种地质过程。使用金刚石压砧在高温高压下原位观测流体的实验,用谱学方法,结合同步辐射光源技术,成为定量化研究地球深部高温超高压流体的有效方法。作者使用同步辐射光源的红外谱研究了10GPa下的NaCl-H2O溶液;在地球化学动力学实验室研究了3GPa,650℃下的NaCl-H2O溶液红外谱,此测量方法可以提供温度压力和体积等数据,能研究其状态。NaCl-H2O溶液红外谱表明水分子主要振动谱受压力和温度影响是不同的。压力增加促使水分子主要振动谱向低波数变化。但是温度增加的效应相反。常温高压下水被压缩,结晶向紧密堆积变化。高温高压下的水有气、液、固和超临界流体各相。水分子间的氢键在近临界态开始减弱,氢键网络被破坏。     

高温高压下电解质溶液热力学性质的研究进展

高温高压下电解质溶液热力学性质的研究不仅对探讨地球内部流体的作用具有重要意义，而且在很多实际工业过程中也都有广泛应用。本综述了近10年来高温高压下电解质溶液热力学参数的实验测量和理论计算的进展，实验设备还有待进一步的改进和完善，以获得更高温度和压力下的数据，理论计算不仅有待于实验的发展，也与溶液的结构理论密切相关。     

高温高压下水的剪切粘滞度的平衡分子动力学计算

本项工作用ＴＩＰ４Ｐ模型对水分子进行了平衡分子动力学模拟。根据Ｇｒｅｅｎ－Ｋｕｂｏ理论,计算了温度从６５２Ｋ到８１４Ｋ,密度从０．５３６０ｇ／ｃｍ３到０．８６３８ｇ／ｃｍ３六个不同温度和密度水的剪切粘滞度,并和实验值进行了对比。在所计算的温度和密度范围,平衡分子动力学计算结果与实验值的平均绝对值差别为１５％,好于使用非平衡分子动力学方法获得的粘滞度值。平衡分子动力学的方法将是获得地学中高温高压下流体输运性质的重要途径。     

高温高压下流体中电解质活度系数的确定

高温高压下流体中电解质的活度系数在地球化学领域有着广泛的应用。本实验测量了100—500℃、0．11—12GPa下0．01mol／L KCl溶液的电导率,并利用Hueckel方程由实验确定的摩尔电导和极限摩尔电导计算出了KCl的平均摩尔活度系数。平均摩尔活度系数随温度升高而减小,随压力升高而增大,而在高温高压下随温度压力的升高几乎保持恒定。     

热液矿床中金属元素的迁移形式

在苏联地质学家向第28届世界地质大会提交的论文中,P.??在研究矿物中流体包裹体的基础上指出,温度在300～500℃时,成矿溶液以含有大量碱金属氯化物和呈碱性反应为特征.矿物溶解度数据与流体包裹体研究结果大体一致,证明高温含矿流体中金属的浓度很高.温度低于300～250℃时,除个别情况外,氯化物含量一般均较低或很低,溶液接近中性反应.随着温度降低、氯离子减少、pH值升高,金属矿物的溶解度降低,使     

Determination of the HCl dissociation constant at a temperature of 350°C and 200 bars of pressure by the potentiometric method using a ceramic electrode

A technique has been developed for pH measurement in flow-through cells at temperatures from 175 to 350°C and pressures up to 350 bars in a nonisothermal cell consisting of a ZrO₂(Y₂O₃) ceramic electrode and a Ag/AgCl (2 M KCl, 25°C) flow-through reference electrode. This technique has been applied to determination of the HCl dissociation constant at 350°C and 200 bars; previously, the HCl dissociation has not been studied sufficiently reliably under these conditions. The obtained value pK _dis = 2.16 ± 0.03 was used to estimate the acidity of fluids from their chemical composition at the vent of high-temperature submarine hydrothermal solutions.     

Dissolution kinetics of magnesite in acidic aqueous solution: a hydrothermal atomic force microscopy study assessing step kinetics and dissolution flux

Magnesite (104) dissolution kinetics were studied in acidic aqueous solutions (2.0 < pH < 4.2) at temperatures between 60 and 90°C by atomic force microscopy (AFM). Comparison of dissolution fluxes obtained by AFM and chemical methods revealed six to seven times larger dissolution fluxes obtained by chemical analysis. Corresponding empirical activation energies were found to be 74 ±22 kJ/mol and 41 ± 4 kJ/mol (at pH 4.2) for the AFM and chemical methods, respectively. The empirical reaction order with respect to proton concentration was 0.36 ± 0.13 and 0.47 ± 0.03 for AFM and chemical methods, respectively. These comparisons suggest that the two experimental measurement methods differ as a result of the different sampling length scales associated with the methods. Negligible changes in step dissolution velocity with changes in bulk pH were found, suggesting that the principal source of increasing dissolution flux with decreasing pH is an increase in step density. However, the observed stable step orientation, which is dependent on pH, suggests that more than one proton adsorption equilibrium should be used to describe the surface chemistry of magnesite in acidic solution.     

地幔中铀的存在状态及其地球化学含义

用235U诱发裂变径迹法对地幔岩捕虏体中铀的分布、含量及存在状态进行了详细的镜下径迹统计,以揭示铀元素在地幔岩中的种种存在状态和分布规律。在此基础上进一步把铀作为不相容元素群的示踪剂(tracer),指示地幔流体在深部地幔岩中的活动轨迹。结果表明,地幔流体能够渗透到各造岩矿物颗粒间隙、浆胞、蚀变边和晶体内部超微裂隙之中(此裂隙宽度很小,约为0.00 n~0.0 n mm)。地幔流体残渣呈极易浸出的非矿物形式的烃碱性物质吸附在超微裂隙之中(浸泡液pH>10)。通过浸泡结果能够大体窥知当初地幔流体的可能地球化学成分。     

常见含水流体包裹体体系pH值的程序计算

常见成矿流体可以近似为CO2-H2O-NaCl体系及其子体系,在成矿过程中一旦被矿物捕获和封存,就会形成流体包裹 体。基于对流体包裹体的热力学研究,可以获得成矿流体的温度、压力和组成等物理化学参数。虽然pH值是一个重要的物 理化学参数,但是对于含水流体包裹体pH值的研究,一直处于探索阶段。目前只有少数研究者实验测定了CO2-H2O-NaCl体 系的pH值,部分研究者建立了热力学模型来计算该体系的pH值。本文结合前人工作,对重要的流体包裹体系（H2O、 NaCl-H2O和CO2-H2O-NaCl） 的pH值计算模型进行了系统归纳,并给出相关体系精确的计算程序。这些体系的执行程序代码 可以从论文出单位或通讯作者获得。     

磷酸盐氧同位素组成的测定方法及分馏机理研究进展

磷酸盐氧同位素组成在古气候和磷的生物地球化学循环研究中都具有十分重要的意义.测定方法和同位素的分馏机理是该类研究的基础.国际上已开展了一系列磷酸盐氧同位素的测定方法和分馏机理研究.在测定方法上,由初期的间接法,经高温还原/裂解法到氟化法,再演化到改进后的高温还原法(包括TC/EA-IRMS法),甚至激光原位技术,样品由实验室纯化学试剂扩展到各种复杂地质样品,在测量精确度、测量速度、样品用量、安全性和技术要求方面都有巨大改进.在分馏机理上,①尽管Longinelli等建立的关系式已获得了天然样品的验证,并认为是平衡分馏,但实验室模拟结果与其还存在较大差异(即没有达到平衡分馏).②在地表温度和pH条件下,无机过程均不会造成水体中溶解态磷酸盐和水之间的氧同位素交换.在高温(>70℃)及不同pH条件下,即使没有生物作用也会造成溶解磷酸盐和水分子之间进行氧的同位素交换,但不同实验室之间结果不一致.③在生物作用存在下,溶解无机磷酸盐和水之间在地表环境会发生强烈氧同位素交换,但除了PPase外,其余均没有达到平衡值.④磷灰石的氧同位素组成要比形成它的溶解态磷酸盐的值高1‰～1.4‰,因此在把Longinelli等关系式用于溶解态磷酸盐和水体系时,需要考虑该因素.同位素平衡分馏和条件有关,认为无机条件下的高温(>70℃)实验结果不一致,以及有生物参与的培养实验结果偏离平衡值,都是实验条件不同所致,包括pH、磷酸盐浓度、生物种类、生物量等.     

流体包裹体研究进展及其在矿床学中的应用

流体包裹体是近年来研究地质流体,尤其是成矿流体的关键途径,各种与之相关的测试技术与方法及理论成果日新月异。流体包裹体研究不仅可以获得成矿流体的物理化学条件,还可以示踪成矿物质来源与组成,为识别矿床类型、构建成矿模式提供直接证据。笔者等从流体包裹体岩相学、均一温度与盐度、成分分析、pH测试与计算、P—V—T—x状态方程、热液金刚石压腔及其在矿床学上的应用7个方面对流体包裹体的研究与发展进行全面的梳理。首先,系统总结了近年来流体包裹体各方面的最新研究进展和发展趋势,分析了流体包裹体成分测试中存在的主要问题,为其发展提供了一定的方向性;其次对各类矿床的成矿流体和流体包裹体特征进行了归纳整理,对分析矿床的成因类型具有重要意义;最后,提出了流体包裹体在矿床学研究中的发展方向。     

A simulating experiment on the geochemical variation trend at the initial period of meteoric waters converting to underground waters and ore fluids

Experimental studies were undertaken on leaching of sedimentary rocks （ dolomite and sandstone） and Hg, Sb ores by distilled water under the condition of a completely open system （room temperature and room pressure）. The aim is to find whether the halogen elements or metal elements first enter the solution at the early stage of meteoric waters converting to groundwaters and ore fluids, and, at the same time, to understand how and when they enter distilled water solutions from the rocks. The experimental resuhs have shown that F and Cl began to enter the fluids in the initial period of thirty days. With increasing leaching duration, the amounts of the elements that entered the fluids increased steadily. During the period from 120 days to 150 days the amounts increased more drastically, followed a slow increase. It is found that the capability of Cl entering the solutions is much greater than that of F. Hg and Sb were found not to have entered the solutions till 120 days later. During this period of time the pH value of the solutions began to drop. As for Hg and Sb ores, Hg and Sb began to enter the solutions on the 60th or 90th day, greatly ahead of schedule, but the two metallic elements in the rock samples began to enter the solutions 150 days later. Relatively speaking, Hg is more easily leached out than Sb from the rocks. In some rock samples, Sb could be detected in the solutions at the end of the experiment. However, Cu, Pb and Zn had not been detected in the leaching solutions from the beginning to the end of the experiment. In the whole leaching process the pH value of the solutions tend to decrease slowly from 7.1 at the beginning to 6.5 at the end. That is to say, in the interaction between pure water and rock the halogen elements in the rocks were preferentially leached out and then entered the fluids. With increasing water/rock reaction duration and amount of halogen-group elements in the solution and with decreasing pH value of the solution, some active metallic elements began to release in small amounts. This experimental result can explain the source and mechanism of volatile components and trace metals in underground waters. Meanwhile, as for those ore deposits produced by ore fluids derived from meteoric waters, the experimental result is also helpful to the understanding of the geochemical variation trend at the initial stage of conversion of meteoric waters to ore fluids.     

流体包裹体研究进展及其在矿床学中的应用

流体包裹体是近年来研究地质流体,尤其是成矿流体的关键途径,各种与之相关的测试技术与方法及理论成果日新月异。流体包裹体研究不仅可以获得成矿流体的物理化学条件,还可以示踪成矿物质来源与组成,为识别矿床类型、构建成矿模式提供直接证据。本文从流体包裹体岩相学、均一温度与盐度、成分分析、pH测试与计算、P—V—T—x状态方程、热液金刚石压腔及其在矿床学上的应用等7个方面对流体包裹体的研究与发展进行全面的梳理。首先,系统总结了近年来流体包裹体各方面的最新研究进展和发展趋势,分析了流体包裹体成分测试中存在的主要问题,为其发展提供了一定的方向性;其次对各类矿床的成矿流体和流体包裹体特征进行了归纳整理,对分析矿床的成因类型具有重要意义;最后,提出了流体包裹体在矿床学研究中的发展方向。     

A spectrophotometric measurement of soil cation exchange capacity based on cobaltihexamine chloride absorbance

Among numerous methods for cation exchange capacity (CEC) determination for soils and sediments, the cobaltihexamine chloride method is frequently used due to its ability to measure CEC at soil pH. After exchange with Co(NH₃)₆³⁺ ions, CEC is estimated via the measurement of the Co remaining in solution. The modified method proposed allows a more rapid determination of CEC based on the measurement of the absorbance at 472 nm of the cobaltihexamine chloride solution before and after exchange. This method has been applied to various soil's horizons from four sites, selected to cover a wide range of CEC and pH values. The model obtained allows one to calculate CEC from absorbance at 472 nm with 95% confidence intervals. As CEC is of relevant meaning in agronomical and environmental purposes, and more recently in ecotoxicological studies, this modified method can be proposed as a rapid test for CEC evaluation.     

Experimental reactions of amphibolite with boron-bearing aqueous fluids at 200 MPa: implications for tourmaline stability and partial melting in mafic rocks

Reactions between hornblende-plagioclase amphibolite and acidic and alkaline B-bearing aqueous fluids have been investigated by experiments at 475°–600° C and 200 MPa. At 600° C, hornblende+calcic plagioclase react to form tourmaline+danburite+clinopyroxene+quartz in acidic fluids containing 0.5–1.0 wt% B₂O₃.Tourmaline is precipitated directly from acidic fluids, and the reaction is driven by neutralization of fluids by Na±Ca derived from the breakdown of reactant solids. The concentration of B₂O₃ in fluids needed to stabilize tourmaline increases as pH increases (above approximately 6.0), and tourmaline is unstable in alkaline fluids (pH > approximately 6.5–7.0) regardless of B concentration. In addition to acid-base relations, tourmaline stability is favored by comparatively higher activity coefficients for Al species in acidic fluids. The concentrations of Al and Si in fluid increase with alkalinity, with the eventual production of felsic borosilicate melts through partial melting of the plagioclase component of the amphibolite. In seeded experiments, tourmaline also contributes components to melt. Partial melting is evident in the range 500°–525° C at 200 MPa in experiments with 8wt% B₂O₃ in fluid as Na₂B₄O₇. The experimental results are applied primarily to metasomatic reactions between mafic rocks and borate fluids derived from granitic magmas, but tourmaline stability and partial melting in mafic regional metamorphic systems are also discussed briefly.