Preparation and Characterisation of Two Geochemical Reference Materials: DG‐H (Granite) and AM‐H (Amphibolite) from the Himalayan Orogenic Belt

Two geochemical reference materials of Himalayan origin named DG‐H (a granite) and AM‐H (an amphibolite) prepared by the Wadia Institute of Himalayan Geology Dehradun are described. Both samples were collected from the NW Himachal Himalaya in India. With the participation of analysts from more than forty international laboratories, element determination data collected during the past 10 years for characterisation of the samples was processed to assign working values using statistical procedures in use for this purpose. Earlier work published on these samples is incorporated in the present communication making it an updated document. The typical chemical and petrological characteristics of these two samples may prove useful for method validation and calibration of analytical instruments used for analysing similar rock types, and for widening the analytical range of several analytical methods used for geochemical analysis.     

Selenium and heavy metals content in some Mediterranean soils

The study of metal contents in industrial, agricultural or/and polluted soils compared with natural or unpolluted soils is currently necessary to obtain reference values and to assess soil contamination. Nonetheless, very few works published appear in international journals on elements like Se, Li and Sr in Spanish soils. This study determines the total levels of Se, Li, Sr, As, Cd, Co, Cr, Cu, Ni, Pb, V, Zn, Fe, Mn and Ba in 14 natural (unpolluted) soils (Gypsisols, Leptosols, Arenosols and Acrisols), 14 agricultural soils (Anthrosols, Fluvisols and Luvisols), and 4 industrial–urban affected-surface soil horizons (Anthrosols and Fluvisols) of Eastern Spain. The geochemical baseline concentrations (GBC) and reference values (RV) have been established, and the relationships among elements and also between soil properties and elemental concentrations have been analysed. The RV obtained in this study were (mg kg⁻¹): Se 2.68, Li 115, Sr 298, Cd 0.97, Co 35, Cr 217, Cu 46, Ni 50, Pb 137, V 120, Zn 246, Fe 124,472, Mn 2691, and Ba 743. The RV for Se and Li were used as a preliminary approach to assess soil contamination in Spanish soils. The results confirm human impact on Sr, As, Cd, Cr, Cu, Ni, Pb and Zn soil concentrations, but evidence no deviation from natural Se, Li, Co, V, Fe, Mn and Ba concentrations. The results obtained from the statistical analysis reveal significant correlations between some elements and clay and soil organic matter (SOM) contents, indicating that metal concentrations are controlled by soil composition. One particularly interesting finding is the high correlation coefficients obtained between SOM and Se, Cd, Cr, V, Fe, and Mn, and between clay and Cd, Zn, V, Fe and Mn. Once again, these facts confirm the role of SOM and clay minerals in soil functions and that soil is an ecosystem element responsible for maintaining environmental quality.     

拉萨地块南部冈底斯~50 Ma负ε_(Nd)(t)花岗质侵入岩的发现及其地质意义

拉萨地块南部冈底斯岩浆带主要形成于中生代–早新生代(205~40 Ma),正的锆石ε_(Hf)(t)和全岩ε_(Nd)(t)显示了新生地壳组分的特征,其形成普遍被认为与新特提斯洋俯冲或印度–欧亚大陆碰撞后的板片断离有关。作者近期的研究工作显示,冈底斯岩浆带中部的早始新世挡顶拉和先弄错纳花岗质侵入岩具有明显的负ε_(Nd)(t)值。锆石LA-ICP-MS U-Pb年龄表明,上述侵入岩形成于~50 Ma,与冈底斯早新生代岩浆大爆发时期(~50 Ma)一致。挡顶拉和先弄错纳侵入岩具有轻稀土元素富集、重稀土元素亏损以及中等的负Eu异常特征,但先弄错纳岩体具有低的稀土元素总量和更明显的轻、重稀土元素分异。挡顶拉和先弄错纳侵入岩具有明显富集的Sr-Nd同位素组成:(~(87)Sr/~(86)Sr)i=0.7096~0.7121,εNd(t)=-7.3~-8.0。这些侵入岩主要可能来自古老地壳的重熔,且其源区组成矿物可能为黑云母+角闪石+石英+斜长石,岩浆在上升过程中经历了结晶分异。尽管目前的研究资料还无法解释这种富集的同位素特征是与拉萨古老地壳的部分熔融有关,还是与俯冲的印度古老大陆地壳物质熔融有关,但是明显负ε_(Nd)(t)值的花岗质岩石在拉萨地块南部冈底斯岩基中部的出现,有可能为新特提斯洋俯冲及印度–欧亚大陆碰撞过程提供新的启示。     

Reference Materials for Geochemical Studies: New Analytical Data by ICP-MS and Critical Discussion of Reference Values

Abundances of twenty four trace elements, including Y and fourteen rare earth elements (REE), are reported for eighty six geological reference materials and four proficiency testing samples. Analytical data were obtained by ICP-MS using solution nebulisation after mixed acid digestion (HF-HClO₄) under pressure. Analysed samples cover a wide range of element concentrations and mineralogical compositions, including samples for which there are few previously published data. Precision for elemental determinations in nearly 90% of the samples analysed is better than 5%. Accuracy, estimated by comparison with data from compilations is better than 6% for well characterized reference materials. Results obtained for samples that are low in trace elements are often significantly lower than compiled reference values. A critical discussion of the compiled data sets, especially for Y and the REEs, indicates that some reference values seem to be erroneous.     

海河平原北部地区土壤地球化学基准值与环境背景值

以北京市、天津市、河北省多目标区域地球化学调查(1:25万)取得的数据为基础,遵循地球化学基准值与环境背景值的概念,根据不同的沉积条件将研究区(即海河平原北部地区)划分为3个统计单元,运用标准化方法,即对土壤表层数据反复剔除异常数据后,通过其他元素与惰性元素Ti的相关关系分别计算得出各指标土壤的基准值;通过对土壤深层数据反复剔除异常数据后,获得了34项指标的平均值、标准离差和变异系数,并以此表征背景值。以上研究为区域土壤环境质量评价与监测预警提供了科学依据。     

核心型钢混凝土柱的轴压比限值试验研究

基于界限破坏时的内力平衡条件,推导了核心型钢混凝土柱轴压比限值的理论计算公式,计算分析了配钢率、混凝土强度等级、柱截面尺寸等因素对核心型钢混凝土柱轴压比限值的影响。进行了5个1/2比例模型柱试件的低周反复加载试验,验证了配置核心型钢对提高混凝土柱的抗震性能和轴压比限值的有效性。计算和试验结果表明,在混凝土柱中配置一定数量的核心型钢,可以有效提高轴压比限值。本文建议的方法可以较为合理地确定核心型钢混凝土柱的轴压比限值,供工程实践参考。     

具有两个公共值和一个公共值对的整函数的唯一性定理

利用加权分担的思想,证明具有2个公共值和1个公共值对的整函数的一个唯一性定理,改进了Brosch G,Alza-hary TC和Yi H X等人的有关结果。     

抚仙湖流域地貌特征及其构造指示意义

以数字高程模型数据为基础, 运用ArcGIS软件平台, 从数字高程模型数据中提取抚仙湖流域内相对独立的61个亚流域, 其中34个位于小江断裂东侧的山地中, 另外27个位于小江断裂西侧的山地中; 然后计算每一个流域单元流域的面积、周长、河流总长、形状指数、平均坡度、相对高差以及高程-面积积分值和水系分支比, 划分流域等级等。通过对流域地貌参数以及高程-面积积分值和分支比等的特征参数的详细分析, 初步表明抚仙湖两侧水系和亚流域的发育具有东西分异的特征。这些特征指示了抚仙湖水系两侧晚新生代构造活动的差异性, 反映了小江断裂带东西两侧的不均衡抬升。小江断裂带的活动控制了抚仙湖流域晚新生代快速隆起, 滇中高原快速隆起以及小江构造带内部差异活动是造成抚仙湖流域东西差异特征地貌的主要原因。      

相关型岩土参数分析和选用

岩土参数与应力环境、沉积条件、风化程度和埋藏条件等因素相关,其统计值具有空间变异性和相关性,采用非相关型岩土统计参数进行岩土工程设计具有不经济性。通过分析岩土参数的变化规律及与其相关的主要因素,说明岩土参数可用深度或参数与地层顶面或底面的距离作为相关参数进行相关型判别,论述相关型参数的判定标准和相关型标准值的计算方法,采用图解法分析相关型参数多种取值方法的可靠性。以华南某核电厂常规岛地基和某变电站边坡为例,介绍了相关型岩土参数标准值经验公式在岩土设计优化中的应用。分析表明：具有规律性变化的岩土参数宜选择恰当的相关参数划分为相关型,相关参数可取参数与地层顶面或底面的距离,相关型岩土参数标准值可使岩土设计方案更具合理性和经济性。     

宿迁市第四纪沉积土层的动力学特征

宿迁市区的地震工程地质条件主要受郯庐断裂带控制。根据这一特点, 在宿迁市区内钻了3个标准孔, 分析研究后确定了第四纪地层的分层年代, 并进行了钻孔波速测试。综合本地区在《宿迁市地震小区划》和对重要建筑进行地震安全性评价过程中积累的数据, 分析了宿迁市不同年代地层场地剪切波速随深度变化的一般规律, 给出了不同沉积年代地层动剪切模量比G/Gmax-和阻尼比-关系的典型值。