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Electron Probe Microanalysis of Bromine in Minerals and Glasses with Correction for Spectral Interference from Aluminium,and Comparison with Microbeam Synchrotron X‐Ray Fluorescence Spectrometry 下载免费PDF全文
Chao Zhang Jinru Lin Yuanming Pan Renfei Feng Renat R. Almeev Francois Holtz 《Geostandards and Geoanalytical Research》2017,41(3):449-457
The strong spectral interference between Br‐ and Al‐induced X‐ray lines hampers the utilisation of electron probe microanalysis (EPMA) for measuring Br mass fractions in Al‐bearing minerals and glasses. Through measuring Br‐free Al‐bearing materials, we established an EPMA method to quantify the overlap from AlKα on BrLβ, which can be expressed as a linear function of the Al2O3 content. The count rate of the BrLβ peak signal was enhanced by high beam currents and long measurement times. Application of this EPMA method to Al‐ and Br‐bearing materials, such as sodalite and scapolite, and to five experimental glasses yielded Br mass fractions (in the range of 250–4000 μg g?1) that are consistent with those measured by microbeam synchrotron X‐ray fluorescence (μ‐SXRF) spectrometry. The EPMA method has an estimated detection limit of ~ 100–300 μg g?1. We propose that this method is useful for measuring Br mass fractions (hundreds to thousands of μg g?1) in Al‐bearing minerals and glasses, including those produced in Br‐doped experiments. In addition, the natural marialitic scapolite (ON70) from Mpwapwa (Tanzania) containing homogeneously distributed high mass fractions of Br (2058 ± 56 μg g?1) and Cl (1.98 ± 0.03% m/m) is an ideal reference material for future in situ analyses. 相似文献
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3D P‐wave traveltime computation in transversely isotropic media using layer‐by‐layer wavefront marching 下载免费PDF全文
Jiangtao Hu Junxing Cao Huazhong Wang Xingjian Wang Renfei Tian 《Geophysical Prospecting》2018,66(7):1303-1314
Subsurface rocks (e.g. shale) may induce seismic anisotropy, such as transverse isotropy. Traveltime computation is an essential component of depth imaging and tomography in transversely isotropic media. It is natural to compute the traveltime using the wavefront marching method. However, tracking the 3D wavefront is expensive, especially in anisotropic media. Besides, the wavefront marching method usually computes the traveltime using the eikonal equation. However, the anisotropic eikonal equation is highly non‐linear and it is challenging to solve. To address these issues, we present a layer‐by‐layer wavefront marching method to compute the P‐wave traveltime in 3D transversely isotropic media. To simplify the wavefront tracking, it uses the traveltime of the previous depth as the boundary condition to compute that of the next depth based on the wavefront marching. A strategy of traveltime computation is designed to guarantee the causality of wave propagation. To avoid solving the non‐linear eikonal equation, it updates traveltime along the expanding wavefront by Fermat's principle. To compute the traveltime using Fermat's principle, an approximate group velocity with high accuracy in transversely isotropic media is adopted to describe the ray propagation. Numerical examples on 3D vertical transverse isotropy and tilted transverse isotropy models show that the proposed method computes the traveltime with high accuracy. It can find applications in modelling and depth migration. 相似文献
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夜间灯光数据驱动的成渝城市群空间形成过程重建及分析 总被引:2,自引:0,他引:2
2016年4月发布的《成渝城市群发展规划》首次正式确定了成渝城市群的内涵和具体边界,重建成渝城市群的形成过程,有利于把握未来发展趋势,并合理优化与调整其发展过程。在重建技术方面,对DMSP/OLS夜间灯光数据传统的不变目标区域校正法加以改进,将成渝城市群2013年城市市区范围内的全部像元加入校正模型的拟合中,设计了统计数据的校正规则,再通过二分比较法较好地恢复了成渝城市群内各城市建成区的时序空间信息。提取面积与统计面积总体平均相对误差为-0.38%,利用高分辨率Google Earth图像验证的建成区提取准确率达到98.29%,相比其他研究结果,经方法改进后的提取结果精度高且稳定。在结果分析方面,基于提取结果展开对城市群建成区重心转移过程与城市聚合过程的深层次研究,剖析了城市群的内部格局与时空变化特征。分析表明,成渝城市群的聚合情况与《成渝城市群发展规划》高度吻合,城市群已进入快速发育阶段,随着区域差异的持续扩大,成都、重庆都市圈的核心地位逐渐形成,而重庆的发展态势稍好。 相似文献
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Li Zhong Huang Guohe Huang Wendy Lin Qianguo Liao Renfei Fan Yurui 《Theoretical and Applied Climatology》2018,132(3-4):1029-1038
Theoretical and Applied Climatology - Apparent changes in the temperature patterns in recent years brought many challenges to the province of Ontario, Canada. As the need for adapting to climate... 相似文献
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自数字海洋的概念提出至今,已有20年整。本文以数字海洋为关键词,检索中国知识资源总库中1999-2018年间公开发表的数字海洋研究文献,综合运用科学知识图谱分析方法,研究总结了20年内数字海洋研究的发展过程、学科参与、研究质量、演进特征等。研究结果表明:①20年来,数字海洋研究成果日益丰富,受关注度逐渐提升;②以海洋科学为中心,多学科共同融合参与;③资源类型全面,但研究质量仍需提升;④前沿热点突出,紧跟信息化潮流。在经历过快速发展阶段之后,当前的数字海洋研究已进入一个相对稳定的阶段,但在研究内容和方法技术等方面仍有探索空间和必要性。分析认为,未来的数字海洋研究应朝着全球化、应用化、精细化、智能化等方向发展,以期进入一个新的研究高潮。 相似文献
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储层含油气后会在地震资料的频谱上出现较为明显的衰减现象,利用这一特征可以进行油气检测。过去更多的计算方法是在高频段计算衰减梯度,并取得了较好的实用效果。随着高精度地震技术的进步,地震资料频带得到拓宽,低频信息也更丰富,提取地震低频信号具有重要的理论和实际意义。在地震低频信号段,研究发展了基于经验模态分解低频能量变化率的高精度的低频信号提取方法,使用该提取方法测试了正演模型,以及对研究区储层岩性油气藏进行了测试,效果与钻井吻合。研究结果表明,研究发展的低频信号提取方法进一步提高了油气检测能力。 相似文献
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中蒙边境内蒙古苏尼特左旗乌兰德勒钼铜多金属矿床是内蒙古二连-东乌旗成矿带上新发现的一个规模较大的矿床。矿床地质特征研究表明,区内发育的隐伏细粒二长花岗岩与钼铜多金属矿床的形成有密切的时空、成因联系。为了揭示本区成矿规律,对细粒二长花岗岩进行了单颗粒SHRIMP锆石U-Pb测年,获得~(206)Pb/~(238)U年龄加权平均值为131.3±1.6Ma(MSWD=1.7),该年龄与矿石中的辉钼矿Re-Os同位素年龄134.1±3.3Ma基本一致,表明其形成时代为早白垩世。地质勘查成果表明,矿床的形成主要与隐伏的燕山期细粒二长花岗岩有着密切关系。上述同位素年龄的获得,为本区成矿规律的研究提供了重要依据。 相似文献