粤北302铀矿床同位素地球化学研究

位于粤北诸广山岩体东南部的302铀矿床是我国规模较大、埋藏较深的花岗岩型铀矿床之一。该矿床产于印支期油洞岩体和燕山早期长江岩体的断裂蚀变带内,矿区内NWW向基性岩脉十分发育,矿体呈似脉状、扁豆状或透镜状。同位素研究表明,矿石的沥青铀矿Sm-Nd和U-Pb等时线年龄（70 Ma）与油洞岩体（232 Ma）、长江岩体（160 Ma）的年龄相差巨大;主成矿期成矿流体的δDH2O值为-65‰～-82‰（平均为-75‰）,δ18OH2O值为6.8‰～0.6‰（平均为3.9‰）,反映出成矿流体主要由地幔流体组成;方解石的δ13C值为-8.4‰～-5.3‰,表明矿化剂ΣCO2也来自地幔;矿区内辉绿岩的（87Sr/86Sr）i值为0.70861～0.70882,花岗岩的（87Sr/86Sr）i值为0.73519～0.77152,萤石的（87Sr/86Sr）i值为0.71474～0.71697,表明成矿组分Sr可能来源于基性脉岩（幔源）与赋矿花岗岩体（壳源）,并呈不同程度的混合,而主成矿组分铀主要来源于赋矿花岗岩体。     

Calcium,Na, K and Mg Concentrations in Seawater by Inductively Coupled Plasma‐Atomic Emission Spectrometry: Applications to IAPSO Seawater Reference Material,Hydrothermal Fluids and Synthetic Seawater Solutions

We report a measurement procedure to determine simultaneously the major cation concentrations (Na, Ca, K and Mg) of seawater‐derived solutions by inductively coupled plasma‐atomic emission spectrometry. The best results were obtained when the IAPSO (‘standard’) seawater reference material was diluted by thirty times with Milli‐Q^® water. We obtained an average reference value r_K (the ratio of the mass fraction of potassium to that of chlorine, i.e., (g kg^?1)/(g kg^?1)) for IAPSO seawater of 0.0205 ± 0.0006 (2.9% RSD), not significantly different from 0.0206 ± 0.0005 (2.4% RSD) for seawater composition reported in the literature. The measured Na, Ca and Mg concentrations correspond to r_Na, r_Ca and r_Mg values of 0.5406 ± 0.0026 (0.5% RSD), 0.02192 ± 0.00048 (2.2% RSD) and 0.06830 ± 0.00047 (0.7% RSD), respectively, in line with previous values measured by wet‐chemistry and atomic absorption spectrophotometry or wet‐chemical titration. Our measurement procedure was used successfully on synthetic seawater solutions and high‐temperature hydrothermal fluids.     

中国内生钼矿床辉钼矿的微量元素特征研究

近年来,金属硫化物微量元素研究取得了重大进展,但主要局限于少数常见的硫化物,如黄铁矿。辉钼矿作为内生金属矿床最常见的金属硫化物之一,目前对其微量元素的研究成果还很少,对微量元素的赋存状态及其揭示的成因意义还不明。文章尝试性地对中国57个内生独立钼矿床或共伴生钼矿床中的辉钼矿进行了ICP_MS微量元素分析。结合元素的地球化学性质及前人的研究成果,认为除Re、Os等少数元素可成类质同象存在于辉钼矿中以外,推测大部分微量元素可能以固溶体出溶、机械混入物或流体包裹体等形式存在于辉钼矿中。各矿床中辉钼矿微量元素相对于中国陆壳富集Cu、Zn、Pb、W等常见的成矿元素,暗示不同地质环境下不同时代和矿床类型的成钼流体搬运的成矿元素具有一致性和普遍性,这是造成钼多金属矿床金属元素矿化分带的基础。辉钼矿的主要微量元素呈对数正相关,受矿床类型和产出环境影响不大;辉钼矿Co/Ni比值多数1,集中于0.01~0.57,不同矿床类型的Co/Ni比值具有一定规律性:当w(Co)30μg/g时,斑岩型和矽卡岩型矿床中辉钼矿的Ni含量比较稳定;当w(Co)30μg/g时,Ni含量比较高;石英脉型矿床的Co/Ni比值变化较大,且小于斑岩型矿床的Co/Ni比值。在内生金属矿床中,辉钼矿主要形成于还原性环境中,但石英脉型矿床的形成条件与斑岩型矿床相比,其氧化性明显增强。根据分析结果和前人研究成果,推测成钼流体应为富CO2和Cl-(个别还富含F-)以及部分还原性气体成分(H2、CO、CH4等)的成矿流体。     

斑岩-浅成低温热液型Cu-Au矿H2O-Cl-S流体性质和演化方式对成矿的制约

斑岩—浅成低温热液型Cu—Au成矿流体最具代表性的是H2O—Cl—S流体。流体的性质强烈控制着Cu、Au的成矿行为,包括溶解性、迁移形式和气—液分配。流体的氧逸度和流体中Cl、S物种相对含量决定金属在流体中的溶解形式,高氧逸度的高温高盐度流体中Cu、Au主要和Cl络合,S-3也可能是促进Au溶解的重要S物种形式。而过量的S有利于Cu、Au等元素以含S离子络合物进入液相流体,与含S中性络合物配分进入气相流体并迁移Au至浅成低温热液环境形成矿床。岩浆需要经历充分的分异,出溶成分和性质有利于金属迁移的流体,形成高品位的斑岩型Cu、Au矿体;上覆叠加浅成低温热液型Au矿体可能需要初始的成矿流体状态进入NaCl—H2O的超临界区、有效的演化方式、良好的流体缓冲环境和有利的Au沉淀场所。相分离和流体—流体反应是沉淀斑岩—浅成低温热液型Cu—Au矿体最重要的流体演化方式。气相流体具有独特的流体性质和演化方式,可能成为十分重要的成矿流体。     

山西平顺西安里铁矿成矿流体特征及演化

[摘 要]对西安里铁矿床蚀变矿物（透辉石、石榴子石、绿帘石和方解石）流体包裹体进行了岩相学、均一温度、盐度和H-O同位素组成分析研究,结果表明：透辉石中流体包裹体均一温度为515℃～622℃,盐度（w（NaCl））为48～75;石榴子石均一温度为475℃～525℃,w（NaCl）均小于26wt%NaCl;绿帘石均一温度为390～440℃,盐度主要分布在40 wt%NaCl左右;方解石均一温度为141～4066oC,w（NaCl）为6.74～21.11;石榴石、透辉石的δD_SMOW值介于-106‰～-86‰,δ¹⁸O_SMOW值介于6.7～8.7‰,δ¹⁸O_H2O值介于2.7‰～8.7‰。磁铁矿δ¹⁸O_H2O值介于2.6‰～6.2‰。综合分析认为：热液主要来源于岩体,在上升过程中萃取了围岩中Na和Cl,Na的加入使大量Fe析出并与Cl结合进行迁移,流体物理化学特征具有显著的变化,导致Fe质析出形成西安里铁矿床。     

Preliminary assessment of the geothermal potential of Rosario de la Frontera area (Salta,NW Argentina): Insight from hydro-geological,hydro-geochemical and structural investigations

This work is part of a project aimed to the development and application of hydrogeological, hydrogeochemical and geological methodologies for the study of the geothermal system of Rosario de La Frontera (NW Argentina).The surface thermal manifestations of this area, whose temperatures range from 22.6 to 92.6 °C, are mainly located in the northern sector of Sierra de la Candelaria anticline. This regional structure crops out between the provinces of Salta and Tucuman (NW Argentina), at the foothills of the central Andean retro-wedge.The present investigation focuses on hydrogeological and structural data, and isotopic compositions (¹⁸O, D and ³H) of thermal springs.Preliminary results allowed to define: i) the meteoric origin of spring water and their long (more than 50 years) residence time at depth, ii) a positive water balance, ranging between 2 and 4 millions of m³/yr, and iii) a conservative geothermal reservoir volume of about 39 km³, iv) a geothermal potential with Er = 5.6*10¹⁸ J and Ef = 0.8*10¹⁸ J.     

脉状铅锌（铜、银）多金属热液矿床研究进展

目前在矿床学分类研究中对沉积岩容贱金属矿床的命名和分类尚未统一,其中一类赋矿围岩为沉积岩、矿体受构造(断层、褶皱等)控制呈脉状产出的、成矿金属为铅锌铜银多金属的矿床成为缺失环节,缺少系统的归纳总结。但该类矿床是造山作用的产物,对其进行归纳综合分析,有助于了解造山作用中的矿质迁移和沉淀过程。本文将该类矿床资料收集,对其成矿特征、控矿构造、成矿流体、矿质来源等进行分析总结。研究表明,此类矿床与造山作用或造山带有着紧密的联系。成矿物质表现为多源性,包括基底围岩、岩浆来源以及幔源贡献。成矿流体具有岩浆流体、变质流体、盆地卤水等多种来源,部分矿床的成矿流体受大气水影响。该类型矿床与MVT铅锌矿床有相似之处,但在成矿环境、控矿因素、金属来源以及成矿流体来源等方面有较大差异。     

含霞石翡翠的成因研究

本文针对鲜有报道的含霞石翡翠,选择了若干具有代表性的样品进行了详细的岩相学、矿物化学、拉曼光谱和X射线粉晶衍射等方面的研究,并对其成因进行了深入探讨。本研究中的样品属于翡翠中的“飘蓝花”品种,为柱粒状结构,主要由硬玉、霞石、角闪石和少量的钡铝硅酸盐等组成。硬玉可分为两个世代,早期硬玉呈自形,发育规则的环带结构,反映了成岩流体的反复补给过程。早期自形的硬玉颗粒部分被后期细粒化的硬玉±角闪石取代,反映了后期流体事件的改造作用。根据产出和成分特征可将霞石分为两种：贫钾霞石和富钾霞石,其中贫钾霞石多沿自形的硬玉颗粒边界分布,而富钾霞石充填在自形的硬玉颗粒之间。根据结构特征可以推测,含霞石翡翠主要是从成岩流体中直接结晶形成的。矿物组成及其成分特征表明该成岩流体主要富集Na、Al、Si、K、Ba以及少量的Ca、Fe、Mg等元素,微量元素则相对富集LREE、HFSE和Sr等元素。结合样品中的矿物相关系和前人的研究结果,含霞石翡翠中硬玉的结晶压力和温度范围分别被限制在0.6～1.4GPa和300～450℃之间,其中霞石代表着母岩减压后流体活动的产物。     

The Mandel–Cryer effect in chemoporoelasticity

Chemoporoelastic theory is an extension of classical Biot poroelasticity that accounts for coupling with the presence and the transport of ions in the pore fluid. The impact of this extra level of coupling can be both substantial and complex. This paper relies on the two variations of Mandel's classical problem, which has become a canonical illustration of the complexity that poromechanical coupling can bring to an otherwise straightforward system. To this end, solutions for a chemoporoelastic shale cylinder and a spherical shale ball are derived. These solutions are then used to demonstrate that chemoporoelastic coupling leads to a coupled pore pressure response that is not only non‐monotonic, as in Mandel's classical case, but also demonstrates the consequences of the semi‐permeable membrane‐like nature of the shale and of the problem's two diffusion‐related timescales. This paper concludes with a discussion of the implications of these results for experimentation and modeling of so‐called reactive shales using chemoporoelastic theory. Copyright © 2009 John Wiley & Sons, Ltd.     

Baroclinic nonlinear exchanges of energy and potential enstrophy in the quasi-geostrophic two-layer model

Abstract

Merilees and Warn's (1975) nonlinear interaction analysis of two-dimensional nondivergent flow is extended to examine the quasi-geostrophic two-layer model. Two sets of triads exist in this model (Salmon, 1978). The purely barotropic triads are the same as the triads examined by Merilees and Warn. Baroclinic-barotropic triads are found to exchange more energy or potential enstrophy with smaller or larger scales depending on the scale of motion as compared with the internal Rossby deformation radius and the relative wavenumber position of baroclinic and barotropic components.