Trace elements and mineral chemistry of silicified wood from Thailand: colours and elemental distribution     

S. Saminpanya 《Australian Journal of Earth Sciences》2016,63(7):873-884

Thai silicified woods were examined using electron probe microanalysis, yielding chemical data that characterised the samples into two groups: low and high silica contents (82—94 wt% and 94—98 wt%). The elements analysed in order of abundance include Si > Fe > Ca > Na > Al > Ti > K > Mg > Mn > Zr. Iron plays a major role in the colour range (red, orange, yellow, brown, grey and black) of the samples. Calcium is associated with Fe in the darker colours of the wood. Pseudo-crystallochemistry has been used for the substitution of trace elements for Si⁴⁺ in silica polymorphs. The atomic channels that run parallel to the c-axis of silica polymorphs or lattice defects, or even the charge balance for trivalent-ion substitution for Si⁴⁺, can accommodate monovalent ions (K⁺ and Na⁺). Vacant and atomic cavities, which are charged balanced by trivalent ions [Al³⁺ or Fe³⁺ substituting for Si⁴⁺], are commonly occupied by divalent ions (Ca²⁺, Mg²⁺ and Mn²⁺). Quadrivalent ions, Ti⁴⁺ and Zr⁴⁺ are non-structurally incorporated but form clusters of mineral inclusions in the samples. Several other trace-element contents are also in the form of mineral/fluid inclusions hosted in the woods.  相似文献   

A Comparison of In Situ Analytical Methods for Trace Element Measurement in Gold Samples from Various South African Gold Deposits          下载免费PDF全文

Christoph Gauert  Mathias Schannor  Lutz Hecht  Martin Radtke  Uwe Reinholz 《Geostandards and Geoanalytical Research》2016,40(2):267-289

Trace element concentrations in gold grains from various geological units in South Africa were measured in situ by field emission‐electron probe microanalysis (FE‐EPMA), laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) and synchrotron micro X‐ray fluorescence spectroscopy (SR‐μ‐XRF). This study assesses the accuracy, precision and detection limits of these mostly non‐destructive analytical methods using certified reference materials and discusses their application in natural sample measurement. FE‐EPMA point analyses yielded reproducible and discernible concentrations for Au and trace concentrations of S, Cu, Ti, Hg, Fe and Ni, with detection limits well below the actual concentrations in the gold. LA‐ICP‐MS analyses required larger gold particles (> 60 μm) to avoid contamination during measurement. Elements that measured above detection limits included Ag, Cu, Ti, Fe, Pt, Pd, Mn, Cr, Ni, Sn, Hg, Pb, As and Te, which can be used for geochemical characterisation and gold fingerprinting. Although LA‐ICP‐MS measurements had lower detection limits, precision was lower than FE‐EPMA and SR‐μ‐XRF. The higher variability in absolute values measured by LA‐ICP‐MS, possibly due to micro‐inclusions, had to be critically assessed. Non‐destructive point analyses of gold alloys by SR‐μ‐XRF revealed Ag, Fe, Cu, Ni, Pb, Ti, Sb, U, Cr, Co, As, Y and Zr in the various gold samples. Detection limits were mostly lower than those for elements measured by FE‐EPMA, but higher than those for elements measured by LA‐ICP‐MS.  相似文献   

江南钨矿带高家塝钨多金属矿床矿化分带特征及其指示意义   总被引：1，自引：1，他引：0  

任康达  张达玉  叶龙翔  孟翔  易洪  黄家龙  万书文  周涛发 《矿床地质》2021,40(2):369-383

高家塝钨多金属矿床位于江南钨矿带北部.钨矿化发育在花岗闪长斑岩与黄柏岭组接触的矽卡岩及其两侧.从岩体向外将矿石划分为:花岗闪长斑岩中细脉浸染状白钨矿矿石(类型Ⅰ)、矽卡岩中浸染状白钨矿矿石(类型Ⅱ)、角岩中脉状白钨矿矿石(类型Ⅲ)3类.高家塝矿床不同类型矿石的白钨矿和磁黄铁矿电子探针(EPMA)分析结果显示,白钨矿w(Mo)从类型Ⅱ(w(Mo)=1.34％～1.40％)→类型Ⅲ(w(Mo)=0.01％～0.17％)→类型Ⅰ(w(Mo)<0.01％)降低.从类型Ⅰ→类型Ⅱ→类型Ⅲ,磁黄铁矿中Cu、Fe元素含量降低;Zn、Co、Ni含量增高.高家塝钨矿床形成白钨矿的成矿流体从类型Ⅱ→类型Ⅲ→类型Ⅰ,氧逸度降低;形成磁黄铁矿的早期石英-硫化物阶段,类型Ⅱ的成矿流体降温速率缓慢,类型Ⅰ和Ⅲ的成矿流体发生快速冷凝作用.区域对比研究显示,高家塝矿床为贫钼白钨矿矿床,形成于还原环境.  相似文献   

电子探针在工艺矿物学中的应用     

伍超群 《岩矿测试》1994,13(1):45-48

文章简述了电子探针分析的原理，并以湖南宝山西铅锌银矿床为例在研究Ｐｂ，Ｚｎ，Ａｇ的赋存状态的基础上，着重探讨了电子探针在矿物命名，矿物形貌特征和组成元素的赋存状态等工艺矿物学方面的应用。  相似文献   

新疆色带电气石成分不均匀性的电子探针研究   总被引：1，自引：0，他引：1  

李德忍  刘国彬 《矿物学报》1988,(3)

作者通过制作色带电气石Fe、Mn、Al、Ca和Na的元素分布等值线图和含量变化梯度剖面图,获得了颜色分带与组成分带的对应关系,并推断出色带电气石生长过程中成矿溶液的变化。  相似文献   

内蒙古大井矿床中银矿物的研究   总被引：1，自引：0，他引：1  

王玉往  王京彬等 《地质论评》2002,48(5):526-533

本文总结了内蒙古大井矿床中银矿物的类型，产出特征以及矿物命名的问题，详细描述了黝铜矿族，浓红银矿，脆银矿，自然银以及含银的铅－铋（锑）硫盐类矿物等主要银矿物的产出状态和化学成分特征，并讨论了相应的形成条件，同时指出本区银矿物主要形成于两个矿化阶段，即：早期黄铜矿－黄铁矿阶段，主要形成了黝铜矿族的含银矿物以及辉锑银矿，硫锑铜银矿等含铜的硫盐类矿物，晚期方铅矿－闪锌矿阶段，形成的银矿物种类较为繁杂，除形成黝铜矿族矿物外，多数含铅，铋的硫盐矿物以及自然银、硫化物和浓红银矿、脆银矿等无铜的简单硫盐等均是在这一阶段形成。  相似文献   

Morphological Characteristics of （K, Na）-Rectorite from Zhongxiang Rectorite Deposit, Hubei, Central China   总被引：3，自引：0，他引：3  

洪汉烈  张晓玲  万淼  侯一俊  杜登文 《中国地质大学学报(英文版)》2008,19(1):38-46

The morphological characteristics of the Zhongxiang (钟祥) rectorite have been studied using X-ray diffraction (XRD), electron probe micro-analyzer (EPMA), scanning electron microscopy (SEM), atomic force microscope (AFM), and high-resolution transmission electron microscopy (HRTEM). The structural formula of the Zhongxiang rectorite is: interstratification of (K, Na)-mica and Ca-montmorillouite. SEM observations show that Zhongxiang rectorite occurs as platy and fold-shaped crystals, and mainly as extremely thin plates with thickness ranging from 0.4 to 0.05 μm and a smooth (001) surface. There are well-developed polygonal steps on the surfaces of some thick crystals, suggesting a layer-by-layer growth mechanism. AFM observations show a series of steps with a height of 2 nm on the platy particles, suggesting the stacking of 20 nm fundamental particles. Club-like or fiber-shaped halloysite is included in the platy crystals with their elongated dimension paralleling (001) of the platy crystals or crossing the (001) surface of the platy rectorite, indicating multi-stage crystallization and involvement of hydrothermal fluids. The Zhongxiang rectorite was generated by both layer-by-layer growth mechanism and dissolution and crystallization growth mechanism with multistages.  相似文献   

从第32届国际地质大会看测试技术在地学中应用的现状和热点     

赵磊  田川 《现代地质》2004,18(4):493-496

讨论了第32届国际地质大会学科和专题命题的情况,统计分析了大会收到的有关测试技术的摘要,介绍了大会有关测试技术学术讨论的主要内容,并以在地质领域被广泛应用的拉曼光谱分析法和电子探针分析方法为例,具体介绍了测试技术在地学应用中的热点和趋势。通过分析和了解,就测试技术的应用与发展阐述了笔者的认识。  相似文献   

Late Pleistocene Eifel eruptions: insights from clinopyroxene and glass geochemistry of tephra layers from Eifel Laminated Sediment Archive sediment cores     

Michael W. Förster  Anastasia Zemlitskaya  Laura M. Otter  Stephan Buhre  Frank Sirocko 《第四纪科学杂志》2020,35(1-2):186-198

The Eifel Laminated Sediment Archive (ELSA), which comprises several cores from maar lakes, includes numerous tephra layers spanning the last 140 000 years. The sediment cores are dated by ¹⁴C and thermoluminescence as well as tuned to Greenland stadial–interstadial successions. Within the last glacial cycle, the Eifel Volcanic Fields are source to several widespread tephra layers, namely the Laacher See, Eltville, Rambach and Rocourt Tephra. However, a corresponding source volcano was so far only identified for the Laacher See Tephra. In this study we use glass and clinopyroxene geochemistry to link the remaining tephra layers to possible eruption centers within the West and East Eifel Volcanic Fields: while we demonstrate that the Eltville Tephra originated from an earlier eruption of the Laacher See Volcano at 24 300 a bp from within the East Eifel Volcanic Field, the Rambach and Rocourt Tephras are sourced from the West Eifel Volcanic Field and erupted from Wartgesberg at 27 900 a bp and Pulvermaar at 75 000 a bp , respectively. Phases of volcanic activity peaked at 10 000–30 000 and 60 000–80 000 a bp and were thus erupted around the temperature minima of the last glacial cycle. The longest phase of dormancy between individual vents was around 30 000 years long, within the last interglacial.  相似文献   

河南栾川赤土店西沟铅锌银矿床中银矿物的赋存状态及成矿机理探讨   总被引：1，自引：0，他引：1  

聂潇  尹京武  陈浦浦  王梦亚  闫星光  张寿庭 《矿物岩石地球化学通报》2015,34(1):184-190

为探讨西沟矿床的成矿物质来源、矿床成因和成矿金属元素赋存状态,本文利用电子探针分析技术,研究了该矿床中银的赋存状态,并探讨了银的成矿机理。结果表明,西沟矿床中银以独立矿物或类质同象产出,主要独立银矿物有自然银、辉银矿和硫铜银矿,主要类质同象矿物为银黝铜矿和含银黝铜矿。辉银矿以显微包体形式赋存于方铅矿中;硫铜银矿呈不等粒集合体分布于黄铜矿颗粒的边部;而自然银呈粒状分布于石英脉及碳酸盐矿物的晶隙间。  相似文献