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1.
μ-XRF技术在黄龙铺钼(铀)矿床铀矿物学研究中的应用 总被引：1，自引：0，他引：1
东秦岭碳酸岩型钼成矿带是全球最大的钼成矿带。该带内的黄龙铺矿床是中国最早发现的碳酸岩型钼矿床之一。最近的野外地质调查发现,部分钼矿石具有较高的放射性异常,但其放射性元素的赋存形式和矿物学特征尚不明确。本文借助聚毛细管微束X射线荧光光谱分析(μ-XRF)分析速度快、原位无损、高灵敏度的分析优势,快速查明铀矿物的空间位置,再结合扫描电镜分析(SEM)和X射线能谱分析(EDS),确定铀矿物的种类及其次生变化。研究表明:黄龙铺矿床高放射性矿石中主要的铀矿物为钛铀矿、铌钛铀矿和晶质铀矿,它们与方解石、长石、黄铁矿、辉钼矿和黄铜矿呈共生关系。矿石中铀矿物后期均遭受氧化性流体改造,发生了明显的蚀变,钛铀矿蚀变之后转变为含Nb的钛铁氧化物,铌钛铀矿和晶质铀矿蚀变后矿物内部形成大量空洞,流体来源可能为大气降水。背散射电子(BSE)图像上灰度差异明显,暗示着矿物中元素分布的不均一性。 相似文献
2.
《Chemie der Erde / Geochemistry》2015,75(2):261-270
The aim of this study was to investigate the accumulation of arsenic (As) in and on roots of Zea mays (maize) and Helianthus annuus (sunflower) by means of synchrotron-based micro-focused X-ray fluorescence imaging (μ-XRF). Plant and soil samples were collected from two field sites in the Hetao Plain (Inner Mongolia, China) which have been regularly irrigated with As-rich groundwater. Detailed μ-XRF element distribution maps were generated at the Fluo-beamline of the Anka synchrotron facility (Karlsruhe Institute of Technology) to assess the spatial distribution of As in thin sections of plant roots and soil particles. The results showed that average As concentrations in the roots (14.5–27.4 mg kg−1) covered a similar range as in the surrounding soil, but local maximum root As concentrations reached up to 424 mg kg−1 (H. annuus) and 1280 mg kg−1 (Z. mays), respectively. Importantly, the results revealed that As had mainly accumulated at the outer rhizodermis along with iron (Fe). We therefore conclude that thin crusts of Fe-(hydr)oxides cover the roots and act as an effective barrier to As, similar to the formation of Fe plaque in rice roots. In contrast to permanently flooded rice paddy fields, regular flood irrigation results in variable redox conditions within the silty and loamy soils at our study site and fosters the formation of Fe-(hydr)oxide plaque on the root surfaces. 相似文献
3.
《Chemie der Erde / Geochemistry》2019,79(2):247-267
Allanite-bearing black coastal sands of Kavala (N. Greece) were studied using a combination of single-crystal XRD, EMPA, μ-XRF, bulk ICP-MS, LA-ICP-MS, μ-XANES and γ-ray spectrometry. The sands are rich in REE (ΣREE + Y: 4010 to 10,810 mg/kg), Th (236–1205 mg/kg) and other critical metals such as Nb, Ta and Co. The main REE- and Th-hosts are allanite and titanite. The allanite unit cell parameters were calculated whereas its formula was found to be (REE0.470Ca1.499Th0.031) (Ti0.031Fe+31.089Al1.880) (Si2.906Al0.094O12) (OH). The μ-XANES spectra showed that LREE are present in trivalent oxidation state. Analyses of the non-magnetic sand fractions showed higher LREE (12,470 mg/kg) due to accumulation of allanite. The materials showed elevated radioactivity ranging from 885 ± 13 to 3467 ± 20 Bq/kg. The obtained results provide new insights on the provenance of the sands, the abundance of REE, Th, and other immobile elements, and offer new clues for potential exploration and exploitation. 相似文献
4.
Shiki Machida Kentaro Nakamura Tetsu Kogiso Ryo Shimomura Koichi Horinouchi Kyoko Okino Yasuhiro Kato 《Island Arc》2021,30(1):e12395
A broad area densely covered by ferromanganese nodules was recently discovered around Minamitorishima (Marcus) Island, representing a high-potential metal resource, particularly for Co, Ni, Mo, and W. We studied 16 nodule samples from nodule fields around Minamitorishima Island. To define the fine-scale chemostratigraphy of the nodules, polished cross-sections of the samples were analyzed by microfocus X-ray fluorescence. Our results show that a general pattern of compositional variation was common throughout the growth history of the nodules in all the regions we studied. Chemical mapping clarified changes in the chemical signature and proportion of five lithological components throughout the growth history: Mn represented columnar δ-MnO2; Fe represented layered amorphous FeOOH*xH2O; Ti represented TiO2*2H2O intergrown with an amorphous FeOOH phase; P, Ca and Y represented particles of biogenic calcium phosphate; and Si, Al, K, Cu, and Ni represented pelagic sediment infills. We proposed a method for a creating a multi-dimensional compositional map of the fine-scale chemostratigraphy observed in the ferromanganese oxide layers on the basis of merging the mapped Mn, Fe, Ti, P, Si and Cu intensities. Multi-dimensional compositional mapping of the sampled nodules from the western North Pacific revealed two fundamental findings: (1) previously recognized first-order Fe–Mn layers, L0, L1, and L2, were further divided into two, three, and four sublayers, respectively, and (2) a delayed supply of material to be nuclei of nodule or a growth hiatus of Fe–Mn layer(s), leading to missing sublayers in the layers L0 and L2, regulated the nodule size. In contrast, layer L1, which does not have any missing sublayers, was commonly observed in the samples for this study and has been reported in studies of other regions in the western Pacific. We propose, therefore, that the layer L1 is a key facies for examining chemostratigraphic correlations with other areas of seafloor. 相似文献
5.
新一代"图谱合一"的星载遥感传感器"推扫式宽视场成像光谱仪"设置了CH18(8.125~8.825μm)和CH19(8.925~9.275μm)这2个波长在10μm以内的热红外通道用于地温反演。为了验证传统的针对10~14μm大气窗口的分裂窗算法在8.0~9.3μm大气窗口的适应性,介绍了基于Sobrino,FrancaCracknell和Becker算法的3种分裂窗算法;针对8.0~9.3μm大气窗口的分裂窗波段设置进行了参数计算公式的修正;并结合MODTRAN提供的热带模型、中纬度夏季模型、中纬度冬季模型、极地夏季模型、极地冬季模型和1976美国标准大气等6种标准大气模型,验证了各算法的地温反演精度。结果表明,FrancaCracknell和Becker算法的误差在2 K以内,可以较好地移植于CH18和CH19的分裂窗反演地温;但现行的3种分裂窗算法都难以保证地温误差小于1 K的要求。 相似文献
6.
Anhua He Gang Zhao Na Xue Jun Wang Bailin Guo Miaoxi Guo Zizhong Fu Institute of Crustal Dynamics China Earthquake Administration Beijing China Earthquake Administration of Tianjin Municipality Tianjin China China Earthquake Networks Center Beijing China 《地震学报(英文版)》2009,(1):101-106
Using Altera's Quartus Ⅱ,Nios Ⅱ IDE and Sopc Builder development tools,the proton precession magne-tometer principle host hardware platform is designed in a cyclone Ⅱ series FPGA chip(EP2C35).The proton precession magnetometer principle host core circuit's single-chip system-logic design is achieved by building and configuring the Nios Ⅱ soft-core processor,developing the IO interface and sensor control circuits,programming some hardware units' VHDL code,for example the equal precision cymometer and the DPL... 相似文献
7.
Reliable chronological frameworks are crucial to paleoenvironmental studies, and high precision 14C dating is the foundation, but many factors, such as dating materials, surficial deposition (influenced by nuclear bomb), and the 14C age plateau, will affect the reliability of the 14C ages and chronology frameworks. In this paper, we present 87 14C dates of different peat fractions from three peat sites in Xinjiang, China. Plant macrofossils, rootlets, the fine fraction of <90 μm, the mid-size fraction of 90–250 μm and the coarse fraction of >250 μm from selected peat samples were measured to investigate the alternative suitable fraction for dating except for plant macrofossils. We discovered that the 90–250 μm component of peat can provide alternative and reliable results in case of plant macrofossils are not available. Additionally, more dating samples from surficial peat deposition were collected, and accurate surface chronological control points were produced by comparing 14C results of plant macrofossils with atmospheric 14C bomb data. Furthermore, multiple data sets with wiggle matching were used along the radiocarbon age plateau to minimize calibrated errors when dates on the 14C age plateau were shown. Finally, radiocarbon chronology frameworks in peat profiles were optimized. In conclusion, we not only focus on the reliable dating materials, but also highlight that the importance of surficial deposition (after 1950AD) and the anomalous 14C dates when establishing the dating framework in peat profiles. Furthermore, we propose that the obtaining chronological control points of surficial peat is an important part of the establishing and improving of peat chronological framework in future research. 相似文献
8.
针对现有岩心扫描仪产品的不足,提出了通过嵌入式μC/GUI图形用户界面的方法,实现基于LCD动态显示的人机界面及各个控制任务调度。阐述了μC/GUI的文件结构,移植步骤和注意事项,编写了相应的LCD驱动文件,实验结果证明系统运行良好。 相似文献
9.
The nano-scale pore systems of organic-rich shale reservoirs were investigated from Upper Ordovician Wufeng and Lower Silurian Longmaxi Formations in southeast Sichuan Basin. These two formations are the most important target plays of shale gas development in China. The purpose of this article is to assess the geometry and connectivity of multi-scale pore systems, and to reveal the nature and complexity of pore structure for these over-mature gas shales. To achieve these objective, total organic carbon, mineralogy, image analyses by focused ion beam-SEM, low pressure nitrogen adsorption, mercury injection capillary pressure (MICP) and spontaneous fluid [deionized (DI) water and n-decane] imbibition were performed.Most of the visible pores from SEM work in Wufeng and Longmaxi shales are within nm- and μm-size regimes and belong to organic matter (OM) pores. The shapes of OM pore in Longmaxi samples are elliptical, bubble-like, irregular or rounded. Wufeng pores are mainly irregular, linear and faveolated, even though two shales have small depth difference, as well as similar thermal maturity, kerogen type and TOC content. Nano-scale pores in Longmaxi are mainly associated with narrow platelike or slitlike pores with pore size of 3–50 nm; while inkbottle pores are dominant in Wufeng samples and over 88% of the pore volume is contributed by pores with diameter <20 nm. Overall, porosity, pore volume and surface area values from Wufeng samples are much higher than those in Longmaxi, which is mainly correlated with the different TOC contents and mineral compositions. MICP tests show that a total of 5 inflection points (indicative of different connected pore networks) are identified in all pressure regions for Longmaxi, while only 2 for Wufeng in high pressure region with the associated permeability at nano-darcy range. Imbibition curves of n-decane are divided into three stages: the initial stage (Stage Ⅰ), linear imbibition stage (Stage Ⅱ) and late imbibition stage (Stage Ⅲ), and the slopes of linear imbibition stage are around 0.5, suggesting well-connected pore spaces for n-decane. In contrast, imbibition curves for DI water are divided in two stages with linear slopes of between 0.25 and 0.5, indicating moderately-connected pore networks for the movement of DI water. This is consistent with the mixed-wet nature of these shales, with observed weak wettability for hydrophilic, while complete wetting for hydrophobic fluids. 相似文献
10.
L. Prieto G. Navarro S. Rodríguez-Gálvez I.E. Huertas J.M. Naranjo J. Ruiz 《Continental Shelf Research》2009
The spatial and temporal distribution of physical, chemical and biological variables of the NE continental shelf of the Gulf of Cadiz were analyzed monthly during almost three annual cycles. This analysis was performed with the aim of deriving the main forcing factors controlling variability at inter-annual, seasonal and short-time scales. Meteorological forcing related to heavy episodes of rainfall that affected river discharges and the wind regime, controlled both the currents along the shelf together and the nutrient concentrations of the surface waters. Meteorological forcing in turn determined the subsequent development and maintenance of phytoplankton blooms. Superimposed on the seasonal cycle typical of temperate latitudes, the inputs of continental nutrients mainly from the Guadalquivir River, along with episodes of upwelling favored by the predominance of westerly winds triggered phytoplankton growth on the shelf, highlighting the markedly relevant role of this large estuary in the control of the biological activity on the shelf. 相似文献