赣南西华山钨矿床成矿流体演化特征

赣南西华山钨矿床是一个闻名中外的大型石英脉型钨矿床。为探讨成矿流体性质以及演化过程,本文对西华山石英脉型钨矿床主成矿阶段含矿石英脉中流体包裹体进行了岩相学、显微测温学研究和激光拉曼光谱分析。结果显示,西华山钨矿床的流体包裹体以H2O-NaCl型为主,局部发育H2O-NaCl-CO2型。流体热焓-盐度图解表明成矿流体以混合作用为主,局部沸腾在热液系统演化中作用不大。通过对沸腾包裹体的测温数据进行计算,得出西华山脉型钨矿成矿压力约为27～87 MPa,矿床形成深度约为1.0～3.3 km。     

Geothermal energy prospects in Brazil: A preliminary analysis

Results of geothermal gradient measurements in 44 localities in Brazil are presented. The Precambrian shield areas are found to be characterized by relatively low temperature gradients in the range 6 to 20°C/km while younger sedimentary basins are characterized by gradients in the range 15 to 35°C/km. An inverse correlation between geothermal gradient and tectonic age has been observed. This as well as the favourable hydrological conditions suggest that the best sites for extraction of geothermal energy in Brazil are the younger sedimentary basins. The Parana Basin is found to offer at present the best site for extraction of geothermal energy in Brazil. Preliminary examination of the temperature distributions in the major aquifer (Botucatu sandstone) suggest that this aquifer contains substantial quantities of warm waters in the temperature range 40 to 90°C. The water layer in this confined aquifer is in convective motion and can be considered as a low enthalphy geothermal system. Many of the routine uses to which geothermal waters are put, such as space heating and soil warming, are not applicable in Brazil mainly because of the favourable climatic conditions. Conversion of this geothermal energy into electrical energy is also unlikely to be economical. Hence we do not consider the Parana Basin geothermal system as an independent ec9nomically exploitable energy resource. However, a few other applications are pointed out where geothermal waters can be used as a supplementary or supporting energy source in increasing the efficiency of economically viable systems utilizing hot waters.     

Low enthalpy geothermal energy resources in Denmark

The deep oil exploration drillings in Denmark have shown that especially the Danish Embayment contains low enthalpy geothermal resources associated with warm aquifers. The most promising reservoirs have been found in highly permeable Upper Triassic sand and sandstone beds, which cover at least 5000 km² at depths of 2000–3000 m and at temperatures of 60–100°C. The porosity of the main reservoir is of 15–25%, and the permeability is presumed to be approximately 1 darcy (10^–12 m²) or higher. A layer thickness of 30–60 m has been observed on a number of localities. Also the Middle Jurassic and the Lower Triassic contain reservoirs of interest. A major geothermal exploration work is planned with seismic investigations, drillings to depths of 2000–4000 m and probably establishment of pilot district heating plants.     

盐湖溶液热化学(Ⅳ) Li_2B_4O_7—Li_2SO_4—LiCl—H_2O体系298.15K时稀释热、热容和表观摩尔热焓的研究

用连续滴定量热法测定了四元体系Li_2B_4O_7—Li_2SO_4—LiCl—H_2O及其次级体系Li_2B_4O_7—Li_2SO_4—H_2O和Li_2B_4O_7—LiCl—H_2O 298.15K时的稀释热,并结合Debye-Hückel热焓极限公式研究了该体系的平均表观摩尔热焓。     

Thermodynamic properties,low-temperature heat-capacity anomalies,and single-crystal X-ray refinement of hydronium jarosite, (H<Subscript>3</Subscript>O)Fe<Subscript>3</Subscript>(SO<Subscript>4</Subscript>)<Subscript>2</Subscript>(OH)<Subscript>6</Subscript>

Crystals of hydronium jarosite were synthesized by hydrothermal treatment of Fe(III)–SO₄ solutions. Single-crystal XRD refinement with R₁=0.0232 for the unique observed reflections (|F_o| > 4_F) and wR₂=0.0451 for all data gave a=7.3559(8) Å, c=17.019(3) Å, V^o=160.11(4) cm³, and fractional positions for all atoms except the H in the H₃O groups. The chemical composition of this sample is described by the formula (H₃O)_0.91Fe_2.91(SO₄)₂[(OH)_5.64(H₂O)_0.18]. The enthalpy of formation (H^o_f) is –3694.5 ± 4.6 kJ mol^–1, calculated from acid (5.0 N HCl) solution calorimetry data for hydronium jarosite, -FeOOH, MgO, H₂O, and -MgSO₄. The entropy at standard temperature and pressure (S^o) is 438.9±0.7 J mol^–1 K^–1, calculated from adiabatic and semi-adiabatic calorimetry data. The heat capacity (C_p) data between 273 and 400 K were fitted to a Maier-Kelley polynomial C_p(T in K)=280.6 + 0.6149T–3199700T^–2. The Gibbs free energy of formation is –3162.2 ± 4.6 kJ mol^–1. Speciation and activity calculations for Fe(III)–SO₄ solutions show that these new thermodynamic data reproduce the results of solubility experiments with hydronium jarosite. A spin-glass freezing transition was manifested as a broad anomaly in the C_p data, and as a broad maximum in the zero-field-cooled magnetic susceptibility data at 16.5 K. Another anomaly in C_p, below 0.7 K, has been tentatively attributed to spin cluster tunneling. A set of thermodynamic values for an ideal composition end member (H₃O)Fe₃(SO₄)₂(OH)₆ was estimated: G^o_f= –3226.4 ± 4.6 kJ mol^–1, H^o_f=–3770.2 ± 4.6 kJ mol^–1, S^o=448.2 ± 0.7 J mol^–1 K^–1, C_p (T in K)=287.2 + 0.6281T–3286000T^–2 (between 273 and 400 K).     

氯化镁及其水合物的标准溶解焓与生成焓

利用精密量热仪测定了MgCl_2、MgCl_2·2H_2O、MgCl_2·4H_2O和MgCl_2·6H_2O在298.15°K溶于水的积分溶解热,并利用Pitzer电解质溶液的。~ΦL方程,计算了溶质的相对表观摩尔热焓,从而得到标准溶解焓分别为(KJ·mol~(-1))—155.86±0.17、—79.45±O.17,—41.78±O.18和—14.58±0.16;晶格能分别为—2490.36,—3158.37,—3772.70和—4376.56。二、四、六水合物的标准生成焓分别为—1289.39,—1898.72和—2497.58;水合焓分别为—76.41,—114.08和—141.28。     

On the problem of boundary conditions in isentropic coordinates

The main advantages of constant potential enthalpy as a vertical coordinate are weaker horizontal velocity gradients in frontal regions and a higher vertical resolution. A disadvantage is the intersection of isentropes with the ground and folding of these surfaces. A numerical model is proposed to overcome the difficulties imposed by the intersection of isentropes with the ground. The model contains a physical and computational domain. The top and bottom surfaces of the computational domain are isentropes whereas the physical domain of the flow confined above by a free surface of constant pressure, and the bottom of this domain is the surface of the earth. In the present study the top surfaces of these two domains coincide (θ _T, P_Tare constants in space and time). The model was tested for the study of frontogenesis and cyclogenesis and integrated for 7 days. The results correspond to enstrophy-conserving finite difference scheme.     

Dissolution Enthalpies of Magnesian Calcites

A series of synthetic and biogenicmagnesian calcites was dissolved in weak acetic acidsolutions to measure the enthalpies of dissolution at25°C. For the synthetic phases, heat releasedwas 33.5 kJ/mol for calcite, decreasing to 33 kJ/molfor a phase of 2 mol % MgCO3, and increasing to35 kJ/mol for a phase of 15 mol %. Values of excessenthalpies, ΔHxs, calculated using calciteand magnesite end-members, average about -1 kJ/mol forthe synthetic phases. Total entropies of solidsolution formation, ΔSSS, also werecalculated using available data on Gibbs free energiesof formation and these excess enthalpies. Values ofΔSSS range from -2 J/(mol-K) at 2 mol % to-5 J/(mol-K) at 15 mol % MgCO3. These negativevalues of ΔHxs and ΔSSSsuggest that some form of ordering (cation?) isobtained in the synthetic phases, and that vibrationalentropies of the solid solution are diminished incomparison to the end-members. In contrast, biogenic samples generally have positivevalues of ΔHxs, increasing from +1 kJ/molat 5 mol % to +3 kJ/mol at 20 mol % MgCO3. Mostvalues of ΔSSS are equal (within errors)to values expected from configurational enthalpyalone. Thus, in most biogenic materials cationordering probably is not obtained, and most phases aremore typical of equivalent-site solid solutions.     

Processes on the Thermodynamic?Properties?of?Lithium?Borates

正1 Introduction Lithium and its compounds as national strategic resources are extensively used in national defense,industrial and agricultural production.As we know,the salt lakes in the western of China are famous for its high     

镉-钙羟基磷灰石固溶体晶须的液相合成及其晶体化学与热力学研究

通过XRD、FT—IR和SEM等方法对采用液相化学反应法合成的镉-钙羟基磷灰石（cadmium—calcium hydroxyapatite,Cd—CaHap）连续固溶体进行分析,结果表明：Cd—CaHap中没有杂质相存在,是纯的固溶体晶须。它们的晶胞参数a和c、晶胞体积V随Cd离子替换量x（原子百分数）的增加呈线性减小,线性方程分别为：a=0．94727—9．159&#215;10^-5x（R=0．9847）;c=0．688682．070&#215;10^-4X（R=0．9815）;V=0．5357—2．74&#215;10^-4X（R=0．9925）。随Cd离子含量的增加,固溶体的标准摩尔生成焓呈线性增加：△fH=46．53402x-13316．31257（R=0．99998）。摩尔混合焓△mH曲线的非对称性则说明替换后的Cd离子在磷灰石结构中可能存在着优先占位的倾向。