刺猬沟金矿石英找矿矿物学研究

石英是刺猬沟金矿重要的脉石矿物,也是金的主要载体.借助于电子顺磁共振、成矿溶液电导度和红外光谱方法对刺猬沟金矿区石英进行了分析.结果表明,电子顺磁共振吸收峰强度、成矿溶液电导度和红外光谱测定的Dco2与石英中Au含量呈正相关关系.成矿溶液电导度＞35.7 μS,DCO2＞0.2矿化好.上述研究获得的信息,对该区找矿和矿床评价具有指导意义.     

Identification and valuation of paramagnetic radicals in natural dolomites as an indicator of geological events

 Geological sedimentary dolomite samples from the Superior Proterozoic are studied using electron paramagnetic resonance (EPR) spectroscopy. The complex spectra in the g=2.0 region is composed of Mn²⁺ lines and signals due to crystallization and radiation-induced defects. Measurements in microwave frequencies of 9.5 GHz (X-band) and 35 GHz (Q-band), and thermal and/or radiation treatments allowed identification of seven paramagnetic radicals in the g=2.0 region: (1) isotropic organic radical; (2) axial SO₂ ⁻; (3) axial PO₂ ⁰ or PO₂ ²⁻; (4) isotropic CO₂ ⁻; (5) axial CO₂ ⁻; (6) axial CO₃ ³⁻; (7) isotropic unknown line. The use of these paramagnetic centres as indicators of geological events is discussed. Received: 18 March 2002 / Accepted: 3 October 2002     

含金黄铁矿中存在晶格金的佐证——以河北省灵寿县土岭—石湖金矿床为例

通过化学物相分析和EPR波谱分析两种方法,对土蛉—石湖金矿床中含金黄铁矿中的金赋存状态进行了研究.含金黄铁矿中存在着主要类型为Au~(+)的晶格金,它的EPR波谱分析的超精细结构谱线g因子=2.001士0.001.分析讨论了HNO_3溶解黄铁矿的氧化还原反应的复杂性以及黄铁矿中含金量与FS谱线强度之间的关系.     

Growth history of hydrothermal chimneys at EPR 9―10°N: A structural and mineralogical study

Based on structural and mineralogical characteristics of four hydrothermal chimney samples collected by submersible Alvin, growth history and formation environment of hydrothermal chimney at EPR 9―10°N are established. It is shown that there occur two types of hydrothermal chimney with different deposition environments at EPR 9―10°N according to differences in their shape, structure and mineral assemblage: type I chimney forms in an environment with high temperature, low pH and strong reducing hydrothermal focus flow and type II chimney forms in a relatively low temperature, high pH and rich Zn hydrothermal environment. Growth of type I chimney begins with the formation of anhydrite. Subsequently deposition of Cu-Fe-Zn sulphide in various directions of chimneys decides the final structure of this type of chimney. According to observation and analysis of mineral assemblages, the formation process of type I chimney could be divided into three stages from early, middle to late. Changes of temperature and major chemical reaction type in the process of hydrothermal chimney formation are also deduced. Different from type I chimney, quenching crystalline of pyrite and/or crystalline of sphalerite provide the growth foundation of type II chimney in the early stage of chimney formation.     

云龙锡矿锡石的振动光谱和电子顺磁共振谱研究

本文用振动光谱和电子顺磁共振谱研究了云龙锡矿锡石的谱学特征。根据红外光谱的谱形、吸收频率和吸收峰强度特征,将云龙锡矿锡石的红外光谱划分成两种类型:A型谱和B型谱。红外光谱特征的研究结合宏观地质特征的研究表明:氧化物阶段锡石的红外光谱为A型谱,硫化物阶段锡石的红外光谱为B型谱。随着锡石成分和结构的变化,锡石的拉曼光谱的谱型、振动频率也发生变化,反映了锡石的成矿条件的差异。云龙锡矿锡石的EPR谱研究表明,云龙锡石中含有呈类质同象进入锡石晶格的V~(4+),根据V~(4+)的稳定场研究,云龙锡石主要形成于相对碱性和偏还原的条件下。     

热处理低温钠长石的EPR和X射线衍射研究

利用电子顺磁共振(EPR)和X射线衍射方法研究了天然和热处理钠长石单晶。热处理在500—850℃水热条件下完成。在外加磁场B平行于晶体c~*轴的方向上,测量了加热前后Fe~(3+)的EPR谱和线宽△B随温度和加热时间的变化。结果显示,线宽随Al、Si无序的增大而增加。由此得出结论,在低温钠长石中,Fe~(3+)位于Al~(3+)占据的T_1(o)位置,在被研究的温度范围内,Fe~(3+)未参与四面体位置T间Al、Si交换。谱线的加宽主要是由在Fe~(3+)邻近位置上Al、Si无序的增大引起的,同时与观测到的晶胞参数变化有关。在Al、Si无序更强的晶体中,Fe~(3+)谱变得极宽。     

9 and 34 GHz EPR study of the free radicals in various asphaltenes: Statistical correlation of the g-values with heteroatom content

The 9 and 34 GHz EPR spectra of eight asphaltenes from different locations have been studied at 294 K in an attempt to correlate the observed g-values with the heteroatom content. It is found that the EPR linewidths are larger and the g-values are smaller at 34 GHz than at 9 GHz. Quantitative statistical analysis of the g-values observed in those asphaltenes derived from tar sand bitumens and crude oils shows that they are uncorrelated with the heteroatom content, unlike those from coal. It is concluded that g-values may not be a good analytical tool for elucidating the structure of those asphaltenes not derived from coal.     

Iron speciation in interaction with organic matter: Modelling and experimental approach

The present study aims to model iron speciation when interacting with natural organic matter. Experimental data for iron speciation were achieved with insolubilized humic acid as an organic matter analogue for 1.8 × 10^− 3 M and 1.8 × 10^− 4 M iron concentrations and 2–5 pH range. Combining EPR spectroscopy and chemical analysis allowed us to fit NICA-Donnan model parameters for both organic complexation of iron and oxides precipitation.     

Color centers in topaz: comparison between neutron and gamma irradiation

Neutron- and gamma irradiation-induced paramagnetic centers in natural colorless topaz from four different Brazilian localities were studied by electron paramagnetic resonance (EPR) and optical absorption as a function of irradiation dose and thermal treatment. Gamma irradiation doses were applied up to 1,000 kGy with a dose rate of 15 kGy h⁻¹. For the neutron irradiation experiments, a neutron flux of 4 × 10¹² cm⁻² s⁻¹ was used with an integrated flux of up to 1 × 10¹⁸ cm⁻². From the experiments, it is concluded that brownish colors are induced by gamma-rays and may be associated with a single broad isotropic EPR line with g = 2.015(2). Both the EPR line and the related optical absorption band at 460 nm (2.7 eV) are lost during thermal treatments between 150 and 200°C. Fast neutrons create the paramagnetic peroxyl radicals O₂ ⁻ and the paramagnetic O⁻ hole centers. The O⁻ centers have the same thermal stability as the optical absorption band at 620 nm (2.0 eV). It is confirmed that the absorption due to the O⁻ center is responsible for the blue color in topaz. Both color centers and their absorption bands are discussed in the context of O⁻ bound small polarons.     

菲对斜生栅藻(Scenedesmus obliquus)自由基的诱导及胁迫效应

通过静态模拟实验,研究不同浓度(0.005、0.01、0.025、0.05和0.1 mg/L)菲暴露96 h后,对斜生栅藻的生长、自由基含量、抗氧化系统以及脂质过氧化产物(MDA)的影响.结果表明,0.01 mg/L菲开始对藻细胞生长产生显著抑制作用,在此浓度下电子自旋共振检测到的自由基信号(g=2.0033,幅宽10.15 mT)显著增强;在浓度设置范围内,超氧化物酶歧化酶、过氧化物酶、谷胱甘肽-S-转移酶活性均被显著诱导,显示出抗氧化系统的应激机制.谷胱甘肽和MDA含量均在0.025 mg/L时被显著诱导.这说明斜生栅藻对菲暴露比较敏感,0.01 mg/L即已显示胁迫效应,自由基的诱导是斜生栅藻产生损伤的重要原因,藻细胞的生长量是比较敏感的损伤指标.