Patterns of rare earth and other trace elements in Paleogene and Miocene clayey sediments from the Mondego platform (Central Portugal)     

《Chemie der Erde / Geochemistry》2015,75(3):389-401

In the present study the origin of clay deposits occurring in an inland platform, in central Portugal, was investigated by their mineralogical and chemical composition. The clay deposits, exploited for ceramic industry are composed of silt-clay facies, the Monteira Member and the Arroça Member, which are assigned to the Coja Formation (Paleogene) and the Campelo Formation (Miocene), respectively. These clayey facies show almost compositional homogeneity, especially concerning texture. The mineralogical composition of the Monteira Member displays slightly higher content in smectite and interstratified clay minerals, which is supported by the chemical composition of samples analyzed. Both members present similar REE patterns, displaying an intense weathering record and little variation in the source area composition. Minor element geochemistry suggests low content in heavy minerals and transition metals. REE patterns and ratios of geochemical parameters support the dominant metasedimentary provenance, with a granite source contribution and also mature recycled sediments of continental origin. The study results’ suggest that the clays of these two members have the same source in terms of lithology and recycled sediments from the Hesperian massif. During the deposition of the Arroça Member, a major remobilization of the Monteira Member is suggested, explaining the geochemical similarity of both facies.  相似文献   

云南兰坪李子坪铅锌矿床的控矿构造、碳和氧同位素及稀土元素地球化学特征   总被引：1，自引：0，他引：1  

胡茂德  张洪瑞  贾敬伍  刘于源 《矿床地质》2015,34(5):1057-1071

李子坪铅锌矿床位于青藏高原东缘的兰坪盆地内,属于白秧坪矿集区的一部分,矿体主要受构造裂隙控制,构造对该矿床具有重要的控制作用。文章对该矿床进行了构造解析,并结合地球化学数据,讨论了该矿床的形成过程。研究表明,李子坪铅锌矿床主要发育3期构造变形:早期为近南北走向的褶皱构造,中期为西倾近似等间距的数条逆断层,晚期形成北西西向与北东东向的平移断层。矿体主要受晚期2组平移断层的控制。各类方解石的δ~(13)C_(PDB)值变化范围为-1.3‰~-2.3‰,平均值-1.7‰;δ~(18)O_(SMOW)值范围为6.9‰~21.0‰,平均值14.8‰。所测各类方解石的∑REE均小于30×10~(-6),∑HREE无明显变化,而∑LREE具有较明显差异,δEu均小于1,显示中等铕的负异常,表明成矿流体存在一定的演化规律。热液矿物方解石中的碳来源于海相碳酸盐岩的溶解作用,氧同位素结果表明成矿流体有大气降水渗入。综合分析认为,李子坪矿床应该为碰撞造山作用下形成的、矿体赋存于构造裂隙破碎带中的铅锌矿床。  相似文献   

硅孔雀石和透视石稀土元素地球化学特征及其成矿环境研究     

汤志云  江冶  汪建明  张梅  乔爱香  肖灵  曹磊 《岩矿测试》2015,34(4):408-413

硅孔雀石和透视石是在热液成矿作用下经过水-岩反应形成的产物,但这一认识缺少稀土地球化学研究成果的支持。本文通过电感耦合等离子体质谱分析获得两种矿物的稀土元素含量,其中硅孔雀石的稀土含量较低(∑REEs=81.2 mg/kg),透视石的稀土含量极低(∑REEs=0.65 mg/kg);两者轻重稀土间分馏较为显著,LREEs/HREEs=3.01和6.05,(La/Yb)N=3.08和7.91。球粒陨石标准化的稀土元素配分模式图均表现为轻微"负铕异常"(δEu=0.565和0.702)、轻稀土富集、重稀土稳定的右倾特征,表明两者物质来源于同一物体。硅孔雀石显著"负铈异常"(δCe=0.219),透视石无"负铈异常"(δCe=0.949),应为两者晶体结构差异所致。研究认为,硅孔雀石和透视石中的稀土元素继承了成矿岩石的稀土特征,证实了两者是在同一氧化条件下通过水-岩反应形成的产物。  相似文献   

基于数字天顶摄影仪的地球自转参数测定方法研究     

任磊  常俊琴  尹东山  李娜  雷鸣 《大地测量与地球动力学》2022,42(4):343-348

为研究利用数字天顶摄影定位方法测定地球自转参数的可行性,结合数字天顶摄影定位原理及时空基准转换差异,详细分析多台站地球自转参数测定及单台站UT1-UTC测定原理,并推导给出相关数学模型。模拟仿真及实测验证结果表明,采用目前高精度天顶摄影定位系统(精度0.05″),通过全国范围内的合理布站,可实现UT1-UTC参数±5 ms、极移参数±0.06″的测量精度。单台站UT1-UTC实测精度为5~8 ms,可满足特定军事工程需求,同时可为多台站联合解算ERP参数提供数据支撑。研究成果可为我国开展地球自转参数测定提供理论参考。  相似文献   

2020年Mw7.7加勒比海地震:反投影成像确定的一次超剪切事件     

曹博男  盖增喜 《地球物理学报》2021,64(5):1558-1568

利用反投影方法,使用美国阿拉斯加台网的远场P波垂直分量地震数据,对2020年1月28日M_W7.7加勒比海地震的破裂过程分两个频段(0.2~1.0 Hz,0.5~2.0 Hz)进行成像.结果显示,地震沿西向单侧近线性破裂,破裂规模约为250 km,破裂时长约为98 s,平均破裂速率约为2.55 km·s^-1.破裂的瞬时速率存在明显波动,在大约53~62 s达到约6 km·s^-1,超过了所在深度的S波速度,为超剪切破裂.地震在5~15 s,21~30 s和66~79 s存在三个高频能量释放峰值,相应时段破裂速率较低,破裂能量得以在局部区域集中释放.破裂一直延伸至大洋中脊附近受阻挡而停止,转换断层几乎完全破裂,释放了加勒比板块和北美板块之间由于相对运动而长期积累的应力.发震断层特殊的空间几何特征和长期积累的应变能,为此次超剪切破裂事件的发生提供了断层几何和动力条件.  相似文献   

D₂₉₀树脂-活性炭吸附富集电感耦合等离子体质谱法测定铜精矿中铂钯   总被引：1，自引：1，他引：0  

胡德新  谷松海  任海  马德起  杨丽飞  苏明跃 《岩矿测试》2013,32(4):572-575

矿产品中痕量贵金属元素的测定通常需要富集分离,在检测过程中谱线干扰较多。本文对铜精矿样品在高温下灼烧除去碳和硫,采用盐酸+王水+氢氟酸消解体系进行分解,利用D290阴离子交换树脂-活性炭作为吸附剂富集铂和钯,以Y、In、Bi为内标元素,105Pd和195Pt作为测量同位素,用电感耦合等离子体质谱法(ICP-MS)测定铂和钯的含量。铂和钯的吸附率均达到90%以上,加标回收率分别为92.0%和96.0%,检出限分别为0.126 ng/g和0.105 ng/g,方法精密度(RSD,n=6)小于4%。应用于实际铜精矿样品分析,测定值与锍镍试金-ICP-MS测定结果一致。本法的样品处理体系最大限度地减少了样品中其他金属离子对待测元素的影响,选择的内标元素和高纯氦碰撞反应可有效地减少基体效应和同质异位素干扰。相比于锍镍试金法,该方法的样品前处理简单,铂和钯的富集效果明显,测定检出限低。  相似文献   

Geoinformatics and digital earth initiatives: a German perspective     

《International Journal of Digital Earth》2013,6(1):17-30

Abstract

This paper discusses the role of Geoinformatics as a new scientific discipline designed for handling of geospatial information. Depending on the scientific background of the people involved in shaping the emerging discipline, emphasis may be placed on different aspects of Geoinformatics. Applications and developments may address geoscientific, spatial planning, or computer science related matters. The scientific field of Geoinformatics encompasses the acquisition and storing of geospatial data, the modelling and presentation of spatial information, geoscientific analyses and spatial planning, and the development of algorithms and geospatial database systems. It is the position of the author that these tools from Geoinformatics are necessary to bridge the gap between Digital Earth models and the real world with its real-world problems (‘connecting through location’). It is, however, crucial that Geoinformatics represents a coherent integrated approach to the acquisition, storage, analysis, modeling, presentation, and dissemination of geo-processes and not a patchwork solution of unconnected fields of activity. Geoinformatics is as such not a part of Geography, Surveying, or Computer Science, but a new self-contained scientific discipline. The current paper highlights international and national trends of the discipline and presents a number of Geoinformatics initiatives. The research and teaching activities of the newly formed Institute for Geoinformatics and Remote Sensing (IGF) at the University of Osnabrueck serve as an example for these initiatives. All these developments have lead to the long overdue formation of a scientific ‘Society for Geoinformatics’ (German: Gesellschaft für Geoinformatik – GfGI) in Germany.  相似文献   

A new global raster water mask at 250 m resolution     

《International Journal of Digital Earth》2013,6(4):291-308

  相似文献   

Development of GIS-based environmental information system: an Indian scenario     

《International Journal of Digital Earth》2013,6(4):382-392

Abstract

Ideally, scientists should be able to format, explore, analyse, and visualise data in a simple, powerful and fast application that would seamlessly integrate georeferenced data from a variety of data sources into an intuitive visualisation. The focus of an Environmental Information System is providing environmental information to decision makers, policy planners, scientists and engineers, research workers, etc. which ensures integration of data collection, collation, storage, retrieval and dissemination to all concerned. All such queries should be responded to supplying substantive information in the form of reports. The paper presents an innovative way to utilise the geographic information associated with the environmental data. The stand-alone application is the integration of using ArcObjects Environmental System Research Institute ArcGIS Engine 9.1 and VB.Net. The geographic information system (GIS)-based application, a framework of digital earth in terms of environmental information system provides a user-friendly query interface, which gives information about various environmental parameters in tabular as well as on map display. It also provides the visual interpretation to make further analysis and future decisions at multiple scales, locations and extents. The facility for modifying the map attributes and corresponding databases is integrated to update the information system. Output spatial data are produced in the form of reports using selected fields with display on map.  相似文献   

Modelling of urban growth boundary using geoinformatics     

《International Journal of Digital Earth》2013,6(4):359-381

Abstract

Urban growth boundary (UGB) is a regulatory measure of local government for delineating limits of urban growth over a period of time. Land within the UGB allows urban development, while the land outside of this boundary remains primarily non-urban. The increasing popularity of UGB demands an easy and effective method to design this boundary. This article introduces a new concept, Ideal Urban Radial Proximity (IURP), to designate a spatial UGB using geoinformatics in the digital environment. The Kolkata urban agglomeration was considered to demonstrate this model. Remotely sensed imageries of three temporal instants (years 1975, 1990 and 2005) were considered to determine the information on urban extent and growth of the city. These data were then used as inputs to model the UGB for the years 2020 and 2035. The proposed model discourages scattered development and increase in urban growth rate. It preserves urban vegetation, water bodies and any other important non-urban areas within the inner city space. The IURP concept will also be useful to make the cities circular and polycentric urban blobs into a monocentric tract. Apart from the proposed model and derived results, this research also proves the potential of geoinformatics in modelling a UGB.  相似文献