西藏帮布勒矽卡岩型铅锌矿床闪锌矿化学成分特征及其地质意义

帮布勒矿床是近年来在西藏冈底斯—念青唐古拉多金属成矿带西段新发现的大型矽卡岩型Pb-Zn矿床。闪锌矿作为该矿床的主要矿石矿物之一,其矿相学特征及化学组分对于揭示成矿物理化学条件和流体演化过程具有重要意义。本文选取帮布勒矿床近端及远端矽卡岩中不同世代闪锌矿开展详细的显微结构观察和电子探针成分研究。结果表明,帮布勒矿床闪锌矿可划分为2个世代:第Ⅰ世代闪锌矿主要产于近端矽卡岩,呈暗红色-棕红色,常与乳滴状黄铜矿共生,并交代他形磁铁矿、磁黄铁矿,Fe元素含量较高(部分闪锌矿Fe含量>10%),Zn/Fe值<10;第Ⅱ世代闪锌矿可进一步分为两类:第一类(Ⅱa)闪锌矿在近端及远端矽卡岩中均有发育,呈棕黄色,充填于辉石、石榴子石等矽卡岩矿物间及其裂隙中;第二类(Ⅱb)闪锌矿主要产于远端矽卡岩中,呈黄色-浅黄色,与方铅矿和石英共生,第Ⅱ世代闪锌矿相比于第Ⅰ世代闪锌矿Fe、Mn含量明显偏低,Zn含量较高。闪锌矿Fe元素温度计估算结果显示,从第Ⅰ世代至第Ⅱ世代成矿温度逐渐降低,分别为160～314℃、138～157℃,与闪锌矿Zn/Fe比值指示结果一致。综上证据,本文认为帮布勒矿床早期成矿流体...     

基于电离层电子含量变化率的周跳探测方法

推导了利用GNSS双频数据的基于电离层电子含量(TEC)变化率的周跳探测方法,分析了电离层平静期和活跃期的TEC变化率,并认为对1s采样率的数据来说无论是否发生电磁暴都不影响TEC变化率法的使用,通过实验证明TEC变化率法能对1s采样率数据中的、其它周跳探测方法较难探测的小周跳进行探测,而联合利用TEC变化率法和MW法可对各自不敏感的周跳组合进行有效探测,实验证明:联合法对电离层平静期和活跃期中、采样间隔为1s的数据中的周跳都具有很高的探测成功率。     

Comparative analysis of coatings on granitic substrates from urban and natural settings (NW Spain)

Rock coatings are frequent on natural rock outcrops and even more on stone surfaces of historical buildings and monuments. They are interesting as some of them have a protective effect against erosion. In the last 30 years, research on rock coatings has been performed separately on either buildings or natural outcrops. This paper studies and compares thin coatings found on granitic rock surfaces of historical buildings with coatings found on natural granite outcrops in a same climatic area (NW Spain) by analysing their surface and cross-sections. As rock surfaces of buildings have known age they can be used to assess rates of weathering and coating growth. This is the first comparative study of formation of coatings on natural and built surfaces in the same region. Both endogenous (rock characteristics) and exogenous factors (climatic conditions, air pollution) that could affect the coatings formation are considered to assess the origin and formation of coatings. X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) analyses of the underlying rocks, XRD analyses of the coatings and Scanning Electron Microscopy (SEM) observations of surface and cross-sections of the coatings, performing Energy Dispersive Spectrometry (EDS) and X-ray maps, were carried out to establish their composition. Fieldwork and results indicate that natural outcrops are widely covered by biological coatings or coatings formed due to rock weathering, while coatings found on rock ashlars are highly variable with air pollution, other building materials, organic droppings and micro-environmental factors contributing to coatings on rock ashlars in a more significant way than substrate characteristics and exposure time.     

应用电子探针技术研究桂西南下雷锰矿床锰钾矿的结构特征

八面体分子筛(OMS-2)具有2×2孔道结构,在离子交换、催化剂、能源和环境等方面具有非常重要的应用价值,然而天然OMS-2矿物材料——锰钾矿在典型结构的成分精细表征和成因研究等方面仍然缺乏.环带和核-边结构在锰氧化物矿物的结构中非常具有代表性,明确其矿物种属、探索其成分特征对于探究其成因、开拓锰氧化物的应用具有重要意...     

Tectono‐metamorphic history recorded in garnet porphyroblasts: insights from thermodynamic modelling and electron backscatter diffraction analysis of inclusion trails

In a Barrovian metamorphic sequence, garnetiferous mica schists document a heterogeneously developed superposition of sub‐orthogonal fabrics and multiple garnet growth episodes. In the variably deformed domains, four types of garnet porphyroblasts have been defined based on inclusion trail patterns. Modelled garnet zoning in the MnNCKFMASHTO system indicates a prograde evolution from 4–4.5 kbar and 490–510 °C to 5–6 kbar and 520–550 °C in the earliest subhorizontal fabric progressing towards 6.5–7.5 kbar and 560–590 °C in the subsequent subvertical foliation. This fabric is heterogeneously deformed into a shallow‐dipping retrograde foliation associated with garnet resorption. In situ electron backscatter diffraction measurements of ilmenite inclusions in individual garnet grains yield precise data on included planar and linear elements. Consistent orientations of internal foliations, lineations and foliation intersection axis sets indicate a superposition of three sub‐orthogonal foliation systems. Weak variations of internal records with increasing intensity of deformation suggest that a moderate buckling stage occurred, but apparent lack of porphyroblast rotation is interpreted as a result of dominant passive flow. Coupling the orientation of internal fabric sets with P–T estimates is used to complement the tectono‐metamorphic evolution of the thickened crust. We demonstrate that garnet porphyroblasts preserve features which reflect large‐scale tectonic processes in orogens.     

Experimental analysis of kaolinite particle orientation during triaxial path

The goal of this study was to analyze the relation between the behaviour of a clayey material at the macroscopic scale and its microfabric evolution. This may lead to a better understanding of macroscopic strain mechanisms especially the contractancy and dilatancy phenomena. The approach proposed in this paper is based on the study of clay particles orientation by SEM picture analysis after different phases of triaxial loading. In the initial state of the samples (one‐dimensional compression), the SEM observations highlight a microstructural anisotropy with a preferential orientation of the particles normal to the loading direction. During isotropic loading, densification of the clayey matrix occurs related to a random orientation of particles indicated by the term ‘depolarization’. In the earlier stages of constant σ₃ drained triaxial path on slightly overconsolidated specimens, the microstructural depolarization seems to persist inside a macroscopic domain, in which only the volumetric strains due to the isotropic part of the stress tensor evolve. Then, a rotation mechanism of the particles towards preferred directions seems to be activated. The phenomenon appears directly linked to the evolution of the deviatoric part of the stress tensor. Copyright © 2010 John Wiley & Sons, Ltd.     

Electron Probe Microanalysis of Environmental Samples: Preparation of Reference Materials, Correction for Particle Size Effects and Representative Results on Sediments Recovered from Snow, Power Station Fly Ash and Bone Samples

In this paper we report the results of electron probe X-ray microanalysis (EPMA) that was used to study environmental materials. The mode of preparation and certification of reference samples based on a basaltic glass matrix for environmental applications of EPMA is described. These samples were prepared containing scandium, strontium and barium (from 0.03 up to 7% m/m) and an evaluation was made of homogeneity, their stability to local heating, followed by analysis by independent methods for certification of composition. Matrix correction procedures for the EPMA technique have been developed for particles having a size commensurable with the volume of X-ray generation. An analytical equation for the size factor is proposed and two techniques for selecting optimum conditions for the analysis of environmental samples by EPMA are reported. These procedures provided satisfactory results when utilized in analysing sediments recovered from snow, coal fly ash and the bones of animals and fish, results from which can be used as indicators for evaluating the pollution level of the lower atmosphere, surface and ground water, as well as revealing pollution mechanisms.     

应用高分辨率透射电镜研究煤显微组分的结构

应用高分辨率透射电镜研究变质系列镜质体和丝质体以及热解碳的物理结构特征表明,随煤级增高,镜质体的基本结构单元(BSU)的平均长度及缩聚芳香层平均环数NC呈增加的趋势;衍射环数增多,环的弥散程度减小,最终出现弧状;表明镜质体的BSU在变质过程中长大,定向性增强,VRo,max=6.50％是阶跃点,当VRo,max>6.50％,BSU突然定向排列。获得了很难获得的低煤化烟煤(VRo,max=0.66％)的高分辨图像,它的BSU尺寸小,无序排列。对丝质体和热解碳高分辨图像的首次研究发现,前者有序性差,随煤级演化的速度较镜质体慢,后者有序性好。     

金矿床中环带状黄铁矿及其生长演化过程的研究

利用电子探针对黔南卡林型金矿床中环带状黄铁矿进行研究，把它划分成三种类型，并分别测定内外带中Ａｓ、Ｓｂ、Ａｕ、Ｈｇ和Ｔｌ等微量元素的含量，绘制了以步间距１μｍ，横穿环带的这五种元素的Ｘ射线强度变化曲线图，图中清楚显示出环带起因于微量元素含量的变化，这五种元素在微观尺度上呈正相关的振荡式变化，具有同源性。讨论黄铁矿经由胶体粒子的聚集、固结与结晶的生长演化过程，提供了低温热液可能是一种富含成矿质的多相