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地球大气圈中40Ar/36Ar的现代比值被公认为295.5,在利用K-Ar法测定地球物质年龄时,它是校正大气氩混染量的重要参数。陨石中原始捕获(trapped)的(40Ar/36Ar)t比值是否和地球大气圈中氩同位素丰度相一致,这个问题不但在地质年龄测定中具有现实意义,而且对探索太阳系的形成和演化也有重要理论价值。近十几年,随着质谱分析技术的提高以及登月计划的实施,国外出现了一批有关月岩中氩同位素原始组分的资料,但至今对陨石中原始氩同位素丰度的报道很少。笔者采用40Ar/39Ar快中子活化技术和约克方程[3,4],对吉林陨石雨2号标本进行了原始捕获的(40Ar/36Ar)t比值进行了测定,并探讨了它的地质意义。 相似文献
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近些年来,人们广泛地利用火山岩的主元素或微量元素的特征对火山岩进行地球化学、成因岩石学和构造岩石学的研究。Mullen(1983)利用玄武岩的 MnO、TiO2和P2O5建立大洋型玄武岩的 MnO×10-TiO2-P2O5×10的构造背景判别图(以下简称MTP图)和圈出了大陆拉斑玄武岩在 MTP 图中的分布范围。他选择了能反映玄武岩形成过程中的重要地球化学特征和成因机制的元素组作为该图的端元组分。 相似文献
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硫酸盐类矿物特别是大洋水中的硫酸盐矿物的硫同位素分布及演化是硫同位素地质学研究的重要内容之一,海水硫酸盐参与海相沉积物中的氧化还原作用是海相沉积物中的硫化物以及矿床硫的主要来源,这也是研究层控矿床的重要依据之一。基于硫酸盐硫同位素的研究在地质上的重要性,国内外对硫酸盐制备SO_2的研究也很重视,在分析方法上趋于简便、高效率、准确性好。目前多数实验室从硫酸盐矿物中制备硫同位素分析样品(SO_2)的方法主要有两种:即 相似文献
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同位素地质年龄标准样的建立,是一项重要的基础工作,它在检查和比较各种实验流程,衡量各种定年方法的可信度,标定同位素稀释剂等方面,都是必不可少的。从1977年初开始,我国同位素地质标准样小组着手建立K-Ar法标准样。为了外检,笔者曾将ZBH-25黑云母、ZBJ角闪石带到澳大利亚国立大学地球科学院进行测定。这两个样品的K-Ar稀释法年龄、40Ar/39Ar坪年龄及40Ar/39Ar等时年龄的一致性表明,这些矿物结晶以后,未受过热的挠动,也不存在过剩氩,是作标准样的理想样品。本文还介绍样品中放射成因40Ar的析出特征,并指出40Ar可能有两种存在状态,它们各具不同的晶格能。 相似文献
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利用配有电阻炉外加热装置的金刚石对顶砧及紧装式六面顶高压容器,在500—1700℃和常压至17.8GPa温压范围内,对AlPO4进行了实验研究。常压下,磷铝石(石英型AlPO4)向鳞石英型AlPO4转变的温度约为778℃,鳞石英型向方英石型AlPO4转变的温度约为1100℃,块磷铝石α-β相转变的温度为586℃。在5.4 GPa和1300℃以下,块磷铝石保持稳定,在5GPa和大于1700℃时,发现AlPO4分解为Al2O3,(刚玉)和P2O5鳞石英型AlPO4在6GPa及500℃转变成斜方晶系新相,新相在室温常压下的晶胞参数为:a=4.930Å,b=7.200Å和c=6.165Å,鳞石英型AlPO4及块磷铝石在11GPa以上均变为NiSO4型结构。文中讨论了AlPO4与SiO2的异同,并给出了一个AlPO4可能的相图。 相似文献
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我們在前一篇文章里曾討論了Ca2+-HPO42--F1--H2O体系中氟对磷酸盐矿物形成影响的若干方面。为了使該項模拟試驗工作更符合于表生作用条件,我們在叶連俊教授的指导下,在上述实驗体系中增加了一个組分--HCO31-,进行了Ca2+-HPO42--HCO31-F1--H2O体系的試驗研究。其目的为进一步探索在合有HCO31-組分的体系中氟对磷酸盐矿物形成的影响,以及CO32-能否进入磷灰石晶格和磷酸盐矿物与碳酸盐矿物的沉积分异順序等問題。 相似文献
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We present a complete set of stability constants (SO4β1) for the monosulfato-complexes of yttrium and the rare earth elements (YREE), except Pm, at I = 0.66 m and t = 25°C, where SO4β1 = [MSO4+] × [M3+]−1[SO42−]−1 (M ≡ YREE and brackets indicate free ion concentrations on the molal scale). Stability constants were determined by investigating the solubility of BaSO4 in concentrated aqueous solutions of MCl3. This is the first complete set to be published in more than 30 years.The resulting SO4β1 pattern is very similar in shape to one reported by de Carvalho and Choppin (1967a) (I = 2 mol/L; t = 25°C) that has been largely ignored. Stability constants vary little between La and Sm, but display a weak maximum at Eu. Between Eu and Lu, SO4β1 decreases by 0.2 log units, substantially exceeding the ±0.02 log unit average analytical precision. The stability constant for Y is approximately equal to that for Er. Our SO4β1 pattern is consequently distinctly different from the consensus pattern, based on a single data set from 1954, which is essentially flat, with a range of only 0.07 log units between the lowest and highest SO4β1 values within the lanthanide series (excluding Y).Values of SO4β1 obtained in this work, in conjunction with the ion-pairing model of Millero and Schreiber (1982), allow prediction of SO4β1 between 0 and 1 m ionic strength. These results are used to assess both the absolute and relative extent of YREE sulfate complexation in acidic, sulfate-rich waters. 相似文献
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E. Davesne K. Dideriksen B.C. Christiansen K.B. Ayala-Luis H.C.B. Hansen 《Geochimica et cosmochimica acta》2010,74(22):6451-6467
In a recent study, sulphate-bearing green rust (GRSO4) was shown to incorporate Na+ in its structure (NaFeII6FeIII3(OH)18(SO4)2(s); GRNa,SO4). The compound was synthesised by aerial oxidation of Fe(OH)2(s) in the presence of NaOH. This paper reports on its free energy of formation .Freshly synthesised GRNa,SO4 was titrated with 0.5 M H2SO4 in an inert atmosphere at 25 °C, producing dissolved Fe2+ and magnetite or goethite. Solution concentrations, PHREEQC and the MINTEQ database were used to calculate reaction constants for the reactions:
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Variation characteristics of CO2 in a newly-excavated soil profile,Chinese Loess Plateau: Excavation-induced ancient soil organic carbon decomposition 下载免费PDF全文
Soils of the Chinese Loess Plateau(CLP)contain substantial amounts of soil inorganic carbon(SIC),as well as recent and ancient soil organic carbon(SOC).With the advent of the Anthropocene,human perturbation,including excavation,has increased soil CO2 emission from the huge loess carbon pool.This study aims to determine the potential of loess CO2 emission induced by excavation.Soil CO2 were continuously monitored for seven years on a newly-excavated profile in the central CLP and the stable C isotope compositions of soil CO2 and SOC were used to identify their sources.The results showed that the soil CO2 concentrations ranged from 830μL·L-1 to 11190μL·L-1 with an annually reducing trend after excavation,indicating that the human excavation can induce CO2 production in loess profile.Theδ13 C of CO2 ranged from–21.27‰to–19.22‰(mean:–20.11‰),with positive deviation from top to bottom.The range of δ13CSOC was–24.0‰to–21.1‰with an average of–23.1‰.Theδ13 C-CO2 in this study has a positive relationship with the reversed CO2 concentration,and it is calculated that 80.22%of the soil CO2 in this profile is from the microbial decomposition of SOC and 19.78%from the degasification during carbonate precipitation.We conclude that the human excavation can significantly enhance the decomposition of the ancient OC in loess during the first two years after perturbation,producing and releasing soil CO2 to atmosphere. 相似文献
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自然界中已发现的硫酸盐矿物主要是表生作用和热液后期的产物,均是在低温、低压条件下形成的。因此,对于硫酸盐化合物来说,由于其结晶条件相似,那么,各种离子(或离子团)在不同的硫酸盐化合物中是否占有大致相同的体积。 相似文献
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根据X射线衍射(XRD)分析发现: A Fe3(SO4)2(OH)6(A=K+、H3O+)系列铁钒的XRD数据十分相近,难以用XRD区别,需通过能谱(EDS)辅助分析,才能区分此类铁矾。另外,此类铁矾的003和107面网间距d随K+含量增大而增大,且呈一元三次方程的关系;而033和220面网间距d随K+含量增大而减小,呈一元二次方程的关系。对该现象从铁矾晶体结构方面进行解释:K+、H3O+离子位于较大空隙中,且沿着Z轴方向排列,当K+、H3O+离子之间相互替换时,会导致该铁矾晶体结构在Z轴方向有较明显的变化。 相似文献
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E.J Reardon 《Geochimica et cosmochimica acta》1983,47(11):1917-1922
The dissociation constant for SrSO04 ion pair was determined at 25°C using conductance and ion-exchange techniques. Both approaches yield values for pK of SrSO04 at zero ionic strength in the range 2.28–2.31. Previously reported values range from 2.1 to 3.0. The refinement in the dissociation constant should allow more reliable appraisals of the extent of strontium mineral solubility controls on strontium concentrations in natural water systems.The Lee and Wheaton conductance model was used to interpret the results of the conductivity measurements in strontium sulphate solutions at 25°C. Because of the limitations imposed by the solubility of celestite, a sufficiently-wide concentration range to enable determination of all three of the parameters—dissociation constant, Λ0, and the distance parameter could not be made. Instead, values are reported for the dissociation constant and Λ0 using reasonable limiting values for the distance parameter.Dowex-50 was used in the ion-exchange technique to determine the dissociation constant for SrSO04. This method was used to determine values at other temperatures as well. Although there is considerable scatter in the temperature data, a standard enthalpy for the dissociation reaction: SrSO04→ Sr2+ + SO2?4 is computed to be 8.7 ± 2 kJmole?1 at 25°C. 相似文献
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N2-CH4(CO2)混合气体在线标样制备及其拉曼定量因子测定 总被引:1,自引:1,他引:0
利用混合气体的标准样品对激光拉曼探针进行标定,可以快速准确地对包裹体中的无机及有机气相组分进行定量分析。而常用的商用钢瓶装混合气体标样,存在费用高、气体组成单一固定等缺点。本文设计了一套在线标样制备装置,提出一种在线配置不同浓度和压力条件下混合气体标样的方法。利用高纯度(纯度99.999%)的N2、CH4以及CO2钢瓶气,经过在线混合增压,在5 MPa和10 MPa条件下制备了N2摩尔分数为30%、50%和70%的N2-CH4以及N2-CO2混合气体在线标样。该方法制备的标样与70%N2+30%CO2的商用钢瓶气标样对比表明,CO2与N2的拉曼相对峰高以及相对峰面积值的误差在4%以内,具有较高的准确度和重现性。通过不同压力和浓度条件下CH4以及CO2的拉曼相对定量因子测定表明,气体的相对定量因子在5~10 MPa压力条件下与压力及组成无关。地质样品应用结果表明,本方法可以方便、灵活、准确地按任意比例将两瓶及两瓶以上纯气体钢瓶样品进行混合及增压,为激光拉曼标定、气体组成原位测量等提供了一种新的技术思路。 相似文献