U – Pb zircon ages from leucogneiss in the Etheridge Group and their significance for the early history of the Georgetown region,north Queensland     

LP Black  IW Withnall  P Gregory    JHC Bain 《Australian Journal of Earth Sciences》2013,60(3):385-401

The Timbarra Tablelands pluton is an extensive (～550 km²) complexly zoned intrusion forming one of many predominantly monzogranite I‐type plutons, which constitute the Moonbi Supersuite in northern New South Wales, Australia. It comprises an outer rim of Rocky River monzogranite (Zones 1–3), an intermediate zone of Sandy Creek syenogranite (Zones 4A–4C), surrounding a core of Surface Hill syenogranite (Zones 5–7). The suite is calc‐alkaline, high‐K, and varies from mildly metaluminous to weakly peraluminous with increasing fractionation. Average Rb/Sr ratios range from 0.4 in the least evolved very coarse‐grained monzogranite (Zone 3) to 46 in the most evolved very fine‐grained biotite microgranite (Zone 6). Trace‐element modelling indicates that the observed compositional variation could have been produced by crystal fractionation. New bulk rock major‐ and trace‐element data for 71 samples are presented, and indicate that a compositional continuum exists that varies between 63 and 78 wt% SiO₂. Importantly, there is no systematic chemical variation with spatial distribution of samples from the core of the pluton to its margin, requiring multiple separate pulses of an evolving magma to explain compositional discontinuities. The pluton is interpreted to have been emplaced at mesozonal levels (～180 ± 60 MPa, 5–10 km depth) and crystallised at temperatures between 620 and 820°C under moderately oxidising conditions (log fO₂ = ‐11.5 to ‐19). The association of gold‐molybdenite mineralisation at Timbarra with moderately oxidised I‐type magmas is consistent with fractionation‐redox controls on ore‐element behaviour in magmatic systems in other studies.  相似文献   

引入城市公共设施要素的人口数据空间化方法研究     

董南  杨小唤  黄栋  韩冬锐 《地球信息科学学报》2018,20(7):918-928

精细尺度的人口分布是当前人口地理学研究的热点和难点,其在灾害评估、资源配置、智慧城市建设等方面应用广泛。城区是人口分布集中的区域,揭示该区域人口分布差异是精细尺度人口空间化研究的核心内容。本研究基于城市公共设施要素点位数据,对居住建筑斑块进行分类,以社区作为人口数据空间化转换尺度,构建各类别斑块面积与人口数量的多元回归模型,生成了宣州城区居住建筑尺度的人口空间数据,揭示了研究区人口空间分布差异。结果表明：① 该方法生成的人口空间数据精度较高,结果可信。779个居住建筑斑块中,估算人数在合理区内的斑块个数占比为35.4%,相对误差在-20%~20%范围内的斑块个数比例之和为61.2%;城东社区、思佳社区作为精度验证单元,其人数估算的相对误差绝对值低于9%;② 城市公共设施要素数据,尤其是中小学及幼儿园、菜市场及水果店,是建筑物尺度上人口分布的指示性因素,其对多层居住建筑人数的估算精度较高,但对中高层居住建筑人数的估算精度偏低。  相似文献   

多元统计在化探数据分析中的应用——以沂源县鲁村镇崮山村地区土壤化探测量为例          下载免费PDF全文

韩学林  王秀芬  孙斌  陈国栋  姜腾龙  潘兆科  胡戈  张春法 《山东国土资源》2018,34(7)

地球化学元素的多元统计分析可以推测地球化学元素在复杂的成矿过程中的组合及演化特征,从而为预测找矿提供有用的微观信息。应用多元统计方法,对沂源县鲁村镇崮山村地区土壤、岩石地球化学测量数据进行研究分析,得出:与中国东部岩石丰度对比,研究区岩石背景特征为Au,Ag,Pb,Sb,As,Hg元素富集,Cu,Zn贫化;与山东省土壤背景值对比,研究区土壤背景值中Au,Ag,Cu,Pb,Zn元素都出现了不同程度的富集。区内成矿元素组合特征表现为:Ag,Pb,Zn元素之间相关性较强,其中Ag、Pb元素之间的相关性最强,反应出了组合成矿的可能性;而Au与其他元素几乎不具相关性,Cu元素与Ag,Pb,Zn元素均具有弱相关性。通过因子分析得出成矿元素的富集与矿化过程大致可以划分3个阶段:Ag-Pb-Zn元素组合的富集与矿化;Cu元素的富集与矿化;Au元素的富集与矿化;反映出了该区多期富集或蚀变矿化特点。利用因子得分圈定元素组合异常,通过异常分析,并结合地质背景、地质构造特征,最终圈定找矿有利靶区,为进一步找矿提供了科学依据。  相似文献   

Three dimensional elasto‐plastic interface for embedded beam elements with interaction surface for the analysis of lateral loading of piles          下载免费PDF全文

Diego F. Turello  Federico Pinto  Pablo J. Sánchez 《国际地质力学数值与分析法杂志》2017,41(6):859-879

This paper presents a numerical formulation for a three dimensional elasto‐plastic interface, which can be coupled with an embedded beam element in order to model its non‐linear interaction with the surrounding solid medium. The formulation is herein implemented for lateral loading of piles but is able to represent soil‐pile interaction phenomena in a general manner for different types of loading conditions or ground movements. The interface is formulated in order to capture localized material plasticity in the soil surrounding the pile within the range of small to moderate lateral displacements. The interface is formulated following two different approaches: (i) in terms of beam degrees of freedoms; and (ii) considering the displacement field of the solid domain. Each of these alternatives has its own advantages and shortcomings, which are discussed in this paper. The paper presents a comparison of the results obtained by means of the present formulation and by other well‐established analysis methods and test results published in the literature. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Probabilistic analyses of soil consolidation by prefabricated vertical drains for single‐drain and multi‐drain systems          下载免费PDF全文

Mohammad Wasiul Bari  Mohamed A. Shahin  Abdul‐Hamid Soubra 《国际地质力学数值与分析法杂志》2016,40(17):2398-2420

Natural soils are one of the most inherently variables in the ground. Although the significance of inherent soil variability in relation to reliable predictions of consolidation rates of soil deposits has long been realized, there have been few studies that addressed the issue of soil variability for the problem of ground improvement by prefabricated vertical drains. Despite showing valuable insights into the impact of soil spatial variability on soil consolidation by prefabricated vertical drains, available stochastic works on this subject are based on a single‐drain (or unit cell) analyses. However, how the idealized unit cell solution can be a supplement to the complex multi‐drain systems for spatially variable soils has never been addressed in the literature. In this study, a rigorous stochastic finite elements modeling approach that allows the true nature of soil spatial variability to be considered in a reliable and quantifiable manner, both for the single‐drain and multi‐drain systems, is presented. The feasibility of performing an analysis based on the unit cell concept as compared with the multi‐drain analysis is assessed in a probabilistic context. It is shown that with proper input statistics representative of a particular domain of interest, both the single‐drain and multi‐drain analyses yield almost identical results. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

AUSTRALIS: A new tool for the study of isotopic systems and geochronology in mineral systems     

S. H. Sie  T. R. Niklaus  D. A. Sims  F. Bruhn  G. Suter  G. Cripps 《Australian Journal of Earth Sciences》2013,60(4):601-611

AUSTRALIS (AMS for Ultra Sensitive TRAce eLement and Isotopic Studies) is a microbeam accelerator mass spectrometry (AMS) system designed for in situ microanalysis of geological samples for trace elements and radiogenic and stable isotope data. The AMS method eliminates molecular and isobaric interferences in in situ mass spectrometric measurements, opening up new opportunities in geochronology and tracer applications. Tests have been carried out for measurements of Pb, S and Os isotopes, conducted mainly at 1.5 MV accelerating voltage. In Pb and S tests, precision as high as 0.3‰ has been obtained, made possible by a fast isotope switching system to counter the effect of instabilities in the ion source and beam transport system. In trace‐element analysis, a detection limit for Au at the sub‐ppb level was obtained.  相似文献   

琼东南盆地深水区钻井岩屑稀土元素地球化学特征及其对沉积物源和环境的指示     

姜龙杰  孙志鹏  翟世奎  刘新宇  尤丽  曹佳琪  张爱滨  毕东杰  张婉 《海洋科学》2018,42(4):89-100

对琼东南盆地深水区YL19A钻井岩屑样品进行了稀土元素(REE)地球化学特征分析,旨在研究琼东南盆地深水区的沉积物源及古环境变化。钻井岩屑样品的球粒陨石标准化REE配分模式总体呈轻稀土(LREE)富集、重稀土(HREE)亏损的右倾式,但在各时代地层之间表现出一定的差异。崖城组和陵水组岩屑呈明显的Eu正异常,而梅山组、三亚组和黄流组岩屑呈Eu的弱负异常,指示了沉积环境和沉积物源上的变化。在早渐新世时期,研究区物源以来自周边凸起的火山碎屑和陆源碎屑为主,沉积环境为海陆过渡相;自渐新世晚期开始,随着琼东南盆地全区发生海侵,研究区水深逐渐加大,沉积环境由海陆过渡相变为浅海相,物源变为远源陆源物质,并具有红河与海南岛多物源混合的特征,红河沉积物对物源的贡献相对较大,基性火山物质对物源的贡献减弱。YL19A钻井岩屑的REE地球化学特征在距今30、28.5、25.5和23.8Ma等地层界面处均发生明显的突变,对区域性构造运动事件有明显的响应。  相似文献   

海水中大分子有机质对铂族元素的吸附动力学研究     

刘凯  高学鲁  邢前国  陈夫山 《海洋学报(英文版)》2019,38(8):8-16

Adsorption kinetics of the interaction between Pt, Pd and Rh(defined here as platinum group elements, PGEs)ions and macromolecular organic compounds(MOCs, 10 kDa), including humic acid, carrageenan and bovine serum albumin, and different cutoff fractions of natural organic matter(1 kDa and 3 kDa) obtained from seawater using centrifugal ultrafiltration devices were investigated. For a given element, all the adsorption kinetics did not reach equilibrium except the interaction between Pt and 1 kDa cutoff, and between Pd and humic acid.For all the tested MOCs, the adsorption kinetics could be divided into two stages, a rapid adsorption process in the first 8 h and the desorption stage after the first 8 h until the equilibrium. The change trend of partition coefficient(log_(10)K_d) values with experiment time was consistent with that of the kinetic curves. However, in the interaction between PGE ions and natural dissolved organic matter(NDOM), an obvious difference in the change trends of log_(10)K_d and kinetic curves was observed. It indicated that the partition behavior of PGE ions interacting with NDOM in seawater was a combined effect of different organic constituents. The adsorption and log_(10)K_d of PGEs in the 1 kDa NDOM fraction were higher and more stable than those in the 3 kDa NDOM fraction. The results also indicated that the 1–3 kDa NDOM may dominate the interaction between PGEs ions and NDOM. Moreover, no kinetic model could perfectly simulate the adsorption process. It indicated that the colloidal struction and morphology of MOCs or NDOM in seawater might be inhomogeneous. Hence, the interaction between PGE ions and organic matter in seawater was a complicated process and needs further research.  相似文献   

台湾以东黑潮沉积物中的生源要素对近千年来气候环境变化的响应     

王启栋  宋金明  袁华茂  李学刚  李宁 《海洋学报》2019,41(2):52-62

基于台湾以东黑潮主流系沉积物中碳、氮、磷等生源要素指标的变化，在沉积物年代学的基础上，探讨了近千年来气候环境变化在黑潮沉积物中的历史记录。结果表明，近千年来台湾以东、琉球岛弧南侧斜坡的黑潮主流区平均沉积速率可达34.2 cm/ka，据其变化可大致分成的3个沉积阶段，与中世纪暖期、小冰期和现代暖期的划分基本一致。沉积物中碳以无机碳为主，总无机碳（TIC）的含量从1850年开始逐渐增大并伴随剧烈波动，恰好与大气CO₂水平的快速升高相对应；总有机碳（TOC）含量的变化则与东亚夏季风强度的变化关系密切，在夏季风较弱的小冰期其含量明显高于夏季风较强的中世纪暖期和现代暖期，这是由于较弱的夏季风有利于亚洲大陆风尘的产生和向海输送，从而促进了研究海域的初级生产力。1850年以来，沉积物中的C∶N∶P逐渐从低于转变为高于Redfield比，反映了上层水体营养盐结构从氮缺乏到氮充足的转变，这与近现代以来急剧增加的全球氮排放密切相关。总体来说，黑潮主流系沉积物中的生源要素指标，明确记录和响应了近千年来的气候环境变化，尤其是近150多年以来不断加剧的人类活动所造成的气候环境剧变。  相似文献   

相对轨道根数的重轨InSAR卫星基线分析与控制     

张涛  万玲  吕孝雷  洪峻 《遥感学报》2019,23(6):1123-1131

星载重轨干涉SAR卫星在高程测绘和形变测量中有着全天时全天候和大范围的优势,其中干涉基线是决定干涉性能的重要指标,而卫星重访轨道对干涉基线起着决定性的作用。通过对现有高分三号干涉数据轨道参数的分析,发现干涉基线相比国外先进卫星过长且稳定性有待提高。本文通过对相对轨道根数和机动控制的分析,得到满足重轨干涉SAR系统要求的稳定基线。以第一次观测的轨道为参考轨道,基于在摄动情况下重复观测轨道与参考轨道的相对轨道根数,计算得到重轨干涉基线的变化规律,并对不同纬度的观测目标进行了样例分析。在基线变化规律的基础上,利用机动速度和相对轨道根数的关系,进一步计算得到满足基线状态需求的机动控制方法。通过实际数据分析,给出了相对轨道根数变化对初始理想构型的影响,验证了重轨干涉基线变化规律符合本文的分析,并利用仿真样例给出了使得重轨干涉基线达到预期要求的机动控制方案。实际数据和仿真实验表明该模型能够通过可长时间观测并准确获得的轨道根数直接计算基线状态,并能从干涉基线需求出发,快速准确的得出对卫星的控制策略。  相似文献