锆石微量元素示踪锂成矿岩浆-热液演化过程

锂成矿过程中的岩浆- 热液演化过程目前仍不清楚。锆石作为花岗岩和伟晶岩中普遍存在的副矿物,其微量元素成分演化可以记录岩浆演化过程。本文以松潘- 甘孜构造带可尔因地区的花岗岩和伟晶岩中的锆石作为研究对象,对其进行原位微量元素分析。锆石的形态结构特征显示花岗闪长岩与花岗岩中的锆石为岩浆锆石,而伟晶岩中的锆石受到不同程度热液作用影响。元素分析结果显示,从太阳河花岗闪长岩到可尔因二云母花岗岩到无锂辉石伟晶岩到锂辉石伟晶岩,锆石中的稀有金属元素(Li、Sn、Nb、Ta和Hf)和U含量逐渐升高,锆石的Zr/Hf比值逐渐降低。除此之外,太阳河花岗闪长岩和可尔因二云母花岗岩中的锆石具有较低的Fe含量,而无锂辉石伟晶岩和锂辉石伟晶岩中的锆石具有明显升高的Fe含量,且锆石Fe含量与稀有金属元素含量具有正相关关系,反映出热液作用越强,稀有金属含量越高的特征。热液导致伟晶岩中锆石的U- Pb体系受到改造,使得获得的年龄不可靠,而伟晶岩铌钽矿U- Pb年龄(210 Ma)相对可靠。基于锆石的微量元素特征,我们认为太阳河花岗闪长岩与锂成矿伟晶岩没有成因联系,二云母花岗岩与锂成矿伟晶岩具有成因联系,但是二云母花岗岩不是成矿伟晶岩的直接母岩。二云母花岗岩和无锂辉石伟晶岩Li锆石/Li全岩接近甚至超过1,指示其与全岩成分不平衡,表明岩浆演化过程中曾形成富锂熔体,且富锂熔体的形成与液态不混溶作用无关,而是岩浆分异的结果。富锂熔体可能在区域拆离断层作用下从岩浆体系中分离,随后不断演化形成了锂辉石伟晶岩,而残余岩浆逐渐冷却结晶形成了二云母花岗岩和无锂辉石伟晶岩。基于锆石中的微量元素可以有效示踪锂成矿过程,并且利用碎屑锆石的微量元素特征还可以指示区域富锂岩浆的存在及其形成时代,有望成为示踪区域锂成矿的一种新方法。     

钢筋混凝土耐久性海洋暴露试验

对不同技术条件的钢筋混凝土试件进行长期的海洋暴露腐蚀试验,以了解其服役特性,为钢筋混凝土结构的耐久性设计提供依据。近7年的暴露结果表明：在混凝土中掺加高炉矿渣等活性掺合料,能大大降低氯离子渗透速率,提高钢筋混凝土的耐久性。     

Salt weathering: influence of evaporation rate,supersaturation and crystallization pattern

Micro- and macroscale experiments which document the dynamics of salt damage to porous stone have yielded data which expose weaknesses in earlier interpretations. Previously unexplained differences are found in crystal morphology, crystallization patterns, kinetics and substrate damage when comparing the growth of mirabilite (Na₂SO₄. 10H₂O) and thenardite (Na₂SO₄) versus halite (NaCl). The crystallization pattern of sodium sulphate was strongly affected by relative humidity (RH), while a lesser RH effect was observed for sodium chloride. Macroscale experiments confirmed that mirabilite (crystallizing at RH > 50 per cent) and thenardite (crystallizing at RH < 50 per cent) tend to form subflorescence in highly localized areas under conditions of constant RH and temperature. This crystallization pattern was more damaging than that of halite, since halite tended to grow as efflorescence or by filling the smallest pores of the stone in a homogeneous fashion, a result which contradicts Wellman and Wilson's theoretical model of salt damage. Low RH promoted rapid evaporation of saline solutions and higher supersaturation levels, resulting in the greatest damage to the stone in the case of both sodium sulphate and sodium chloride crystallization. At any particular crystallization condition, sodium chloride tended to reach lower supersaturation levels (resulting in the crystallization of isometric crystals) and created negligible damage, while sodium sulphate reached higher supersaturation ratios (resulting in non-equilibrium crystal shapes), resulting in significant damage. ESEM showed no damage from sodium sulphate due to hydration. Instead, after water condensation on thenardite crystals, rapid dissolution followed by precipitation of mirabilite took place, resulting in stone damage by means of crystallization pressure generation. It is concluded that salt damage due to crystallization pressure appears to be largely a function of solution supersaturation ratio and location of crystallization. These key factors are related to solution properties and evaporation rates, which are constrained by solution composition, environmental conditions, substrate properties, and salt crystallization growth patterns. When combined with a critical review of salt damage literature, these experiments allow the development of a model which explains variations in damage related to combinations of different salts, substrates and environmental conditions. Copyright © 1999 John Wiley & Sons, Ltd.     

Significance of stemflow in groundwater recharge. 1: Evaluation of the stemflow contribution to recharge using a mass balance approach

Stemflow was evaluated in a water balance and its contribution to groundwater recharge determined. Gross precipitation, throughfall and stemflow were measured for one year in a pine forest (Tsukuba, Japan) to determine each component of the water balance in the forest. Groundwater recharge rates by stemflow and throughfall were calculated from a mass balance method using chloride in subsurface waters. The stemflow in the water balance was relatively small when estimated as a value per canopy projected area of the tree in the forest. However, the results for the mass balance of chloride in subsurface waters indicated that it was impossible to disregard the stemflow in determining groundwater recharge. Although the ratio of stemflow to the net precipitation was small in the water balance, the effect of stemflow on groundwater recharge was relatively large.     

无机阴离子及溶解性有机质对程海化学需氧量测定值的影响

自2005年以来,程海水体的化学需氧量(COD)持续升高,而生化需氧量(BOD)却维持不变,高锰酸盐指数(COD_(Mn))升高也较缓慢.为研究程海COD持续升高的原因,选取程海水体中具有代表性的无机阴离子(Cl~-、F~-、S~(2-)、HCO_3~-)和溶解性有机质(DOM)中不同浓度的胡敏酸(HA)、富里酸(FA)和商品化腐殖酸(SHA),研究其对COD和COD_(Mn)测定的影响,探讨Cl~-和DOM共同存在下对COD测定的影响.结果表明:程海水体中Cl~-浓度对COD存在显著影响,产生的COD值为5.42 mg/L,S~(2-)、F~-和HCO_3~-对COD影响较小;各离子对COD_(Mn)的影响很小;不同浓度梯度的HA、FA和SHA与COD测定结果呈显著线性相关,氧化1 mg C HA、FA和SHA所产生的COD值分别为2.164、1.964和2.362 mg;氧化1 mg C HA和FA所产生的COD_(Mn)值分别为0.646和0.344 mg;DOM对COD测定值的影响显著大于对COD_(Mn)测定值的影响;且一定浓度Cl~-的存在增强了FA与HA对COD测定的影响.该研究为进一步阐明程海COD逐步升高,COD_(Mn)值缓慢升高的内在原因奠定了基础.     

高温Li/SOCl2电池及其作为钻探设备电源的应用

介绍了高温Li/SOCl2电池的特性,分析了高温Li/SOCl2电池可能出现的不良状况及其在钻探设备的井下仪器仪表中的使用条件,讨论了电池的滞后特性和安全性能对钻探设备中井下仪器仪表正常工作的影响,介绍了地质钻探工程设备中科学地使用高温Li/SOCl2电池的方式、方法和条件.     

A comparison of groundwater recharge estimation methods in a semi‐arid,coastal avocado and citrus orchard (Ventura County,California)

We assess the relative merits of application of the most commonly used field methods (soil‐water balance (SWB), chloride mass balance (CMB) and soil moisture monitoring (NP)) to determine recharge rates in micro‐irrigated and non‐irrigated areas of a semi‐arid coastal orchard located in a relatively complex geological environment. Application of the CMB method to estimate recharge rates was difficult owing to the unusually high, variable soil‐water chloride concentrations. In addition, contrary to that expected, the chloride concentration distribution at depths below the root zone in the non‐irrigated soil profiles was greater than that in the irrigated profiles. The CMB method severely underestimated recharge rates in the non‐irrigated areas when compared with the other methods, although the CMB method estimated recharge rates for the irrigated areas, that were similar to those from the other methods, ranging from 42 to 141 mm/year. The SWB method, constructed for a 15‐year period, provided insight into the recharge process being driven by winter rains rather than summer irrigation and indicated an average rate of 75 mm/year and 164 mm/year for the 1984 – 98 and 1996 – 98 periods, respectively. Assuming similar soil‐water holding capacity, these recharge rates applied to both irrigated and non‐irrigated areas. Use of the long period of record was important because it encompassed both drought and heavy rainfall years. Successful application of the SWB method, however, required considerable additional field measurements of orchard ET_c, soil‐water holding capacity and estimation of rainfall interception – runoff losses. Continuous soil moisture monitoring (NP) was necessary to identify both daily and seasonal seepage processes to corroborate the other recharge estimates. Measured recharge rates during the 1996 – 1998 period in both the orchards and non‐irrigated site averaged 180 mm/year. The pattern of soil profile drying during the summer irrigation season, followed by progressive wetting during the winter rainy season was observed in both irrigated and non‐irrigated soil profiles, confirming that groundwater recharge was rainfall driven and that micro‐irrigation did not ‘predispose’ the soil profile to excess rainfall recharge. The ability to make this recharge assessment, however, depended on making multiple field measurements associated with all three methods, suggesting that any one should not be used alone. Copyright © 2000 John Wiley & Sons, Ltd.     

川西扎乌龙花岗伟晶岩型锂矿床成矿作用过程——来自流体包裹体与同位素的证据

川西扎乌龙花岗伟晶岩型锂矿床位于甘孜-松潘造山带内,为大型锂矿床.前人基于对扎乌龙系统的流体包裹体研究,认为扎乌龙锂矿形成于500～580℃,压力350 MPa的环境.然而,对于扎乌龙成矿流体的来源及其何种流体挥发分对成矿起主导作用,仍缺乏有效制约.锂辉石型伟晶岩脉是扎乌龙锂矿最富集的类型,脉体内部分带性良好,可划分为4个带:石英-白云母带、斜长石带、钠长石-锂辉石带和石英-锂辉石带.根据地质现象和流体包裹体的岩相学观察,扎乌龙锂辉石型伟晶岩脉可划分为伟晶岩阶段和热液阶段2个主要阶段,锂矿化集中于伟晶岩阶段.文章对扎乌龙成矿流体的来源及成分开展了研究,即对锂辉石型伟晶岩各阶段的流体包裹体进行了激光拉曼光谱、群体包裹体和氢、氧、碳同位素分析.流体包裹体成分揭示,成矿流体由伟晶岩阶段的高温(500～580℃)、低盐度(w(NaCleq)0.8％～8.5％)、富挥发分(Li、P、B等)、弱碱性的硅酸盐水体系,向晚期中高温(300～400℃)、低盐度(w(NaCleq)4.4％～9.6％)、富CO2、弱酸性的盐水体系热液演化.氢、氧同位素组成表明早期成矿流体以岩浆水为主,晚期无明显的大气降水加入.碳同位素分析结果表明,二氧化碳主要来源于岩浆出溶.结合已有的研究成果,笔者认为相对封闭的成矿环境导致挥发组分的大量聚集和弱碱性环境,是扎乌龙锂矿富集与沉淀的主要控制因素.晚期贫F、富Cl的弱酸性热液流体有利于锂辉石的保存.     

浓氯化钙水溶液中高配位Ca-Cl离子团簇:分子动力学模拟研究

采用分子动力学(MD)模拟研究了5.55 mol·kg~(-1)氯化钙溶液的微观结构特征,尤其是溶液中高配位Ca-Cl离子团簇的结构与性质,探究了温度对于高配位Ca-Cl离子团簇的影响。结果显示,5.55 mol·kg~(-1)氯化钙溶液中,除形成[CaCl]~+、[CaCl_2]~0离子对外,还存在一些高配位[CaCl_x]~(2-)~x(x=3～6)离子团簇。高配位[CaCl_x]~(2-)~x(x=3～6)离子团簇在5.55 mol·kg~(-1)氯化钙溶液中介稳存在,易解离或进一步缔合形成更大Ca-Cl离子团簇,这可能与溶液中大量未完全水合Ca~(2+)对高配位[CaCl_x]~(2-)~x(x=3～6)离子团簇水壳层的扰动破坏有关。温度升高,氯化钙溶液中Ca-Cl离子缔合增强,但高配位Ca-Cl离子团簇的平均存在时间(t_(av))减小,这表示高温下溶液中Ca-Cl离子团簇频繁地解离与缔合,离子团聚趋势更为显著。本工作观测到的高配位[CaCl_x]~(2-)~x(x=3～6)离子团簇可能是浓氯化钙溶液Ca-Cl离子缔合过程中一种热力学不稳定结构,但这些高配位Ca-Cl离子团簇的形成可能对溶液结晶及相关化学过程产生不利影响。     

盐湖氯化镁制备炼钢用镁钙造渣剂的实验研究

本文探讨了盐湖副产氯化镁应用于炼钢冶金造渣的可行性。以盐湖水氯镁石和石灰为原料,通过化学合成制备了氧化镁,再将氧化镁与石灰、粘结剂混配成型制备炼钢用镁钙造渣剂,考察了粘结剂硼酸的不同用量时造渣剂形成的球团强度和抗压强度及微观结构变化;同时研究了不同煅烧温度、煅烧时间、氧化镁掺杂量的情况下,造渣剂的活性及杂质脱除率。实验结果表明,利用该方法制备的镁钙造渣剂应用于钢铁冶金造渣过程,可有效地脱除碳、磷、硫、硅等杂质成分,提高转炉冶炼的冶金效果的同时实现了盐湖资源再利用,具有较好的推广应用前景。