Comparison of testing techniques and models for establishing the SWCC of riverbank soils     

Soonkie Nam  Marte Gutierrez  Panayiotis Diplas  John Petrie  Alexandria Wayllace  Ning Lu  Juan Jorge Muñoz 《Engineering Geology》2010,110(1-2):1-10

The soil water characteristic curve (SWCC), also known as soil water retention curve (SWRC), describes the relationship between water content and soil suction in unsaturated soils. Water content and suction affect the permeability, shear strength, volume change and deformability of unsaturated soils. This paper presents results of the laboratory determination of the SWCC for soil samples obtained from the riverbank of the Lower Roanoke River in North Carolina. Six different testing methods were used to establish the SWCC including the filter paper, dewpoint potentiameter, vapor equilibrium, pressure plate, Tempe cell and osmotic methods. It is concluded that each suction measurement technique provides different measurable ranges of suction values, and the combined results from the different tests provide continuous SWCCs. Three widely available models were also shown to adequately fit the experimental SWCC data, particularly for matric suction values under 1500 kPa. These results will be valuable to practitioners in deciding which methods to use to establish the SWCC, and which empirical relationship to use for modeling the SWCC of riverbank soils.  相似文献   

天津滨海新区地热流体水化学特征分析     

阮传侠  于彦  高宝珠  王娟  田信民 《地下水》2010,32(1):51-53

根据以往的水化学资料,分析天津滨海新区地热流体的水化学特征,结合滨海新区的构造条件,分析水化学特征与该区构造的关系,提出天津滨海新区主要开发热储层明化镇组和馆陶组热储层有关矿化度,水化学类型分布和上下储热层水的联系的三个结论。  相似文献   

桐柏北部宽坪群变泥质岩的变质作用研究   总被引：1，自引：0，他引：1       下载免费PDF全文

胡娟  刘晓春  曲玮 《地学前缘》2010,17(1)

桐柏北部宽坪群发育一套由斜长角闪岩、变泥质岩、大理岩以及石英岩夹层组成的中级变质岩石。本文选取4个含石榴变泥质岩样品进行了详细的岩石学研究,其中回龙寺组的一个样品含有特征的十字石+蓝晶石组合,而左老庄组的一个样品则含有夕线石。回龙寺组样品中的石榴石均具有明显的进变质成分环带,而左老庄组样品中的石榴石均遭受到晚期低温扩散的影响,所以在计算其形成条件时选取了生长于峰期变质阶段的特定部位。运用传统的石榴石-黑云母-白云母-斜长石-石英地质温压计估算回龙寺组的变质p-T区间为590～610℃、0.95～1.14GPa,左老庄组为630～650℃、0.65～0.89GPa,分别相当于低角闪岩相和高角闪岩相。这一结果与变质反应曲线所限定的温压范围基本一致,并且后者中还存在由蓝晶石区域向相对高温低压的夕线石区域转变的过程。低-高角闪岩相的宽坪群与低角闪岩相的二郎坪群和麻粒岩相的秦岭群紧密伴生,且变质时代近于一致(440～400Ma),说明华北南缘在志留纪—早泥盆世发生了岛弧、微陆块与华北板块大陆边缘的碰撞造山作用。  相似文献   

塔里木柯坪地区奥陶系层序地层与同位素地球化学响应特征   总被引：2，自引：0，他引：2  

胡明毅  钱勇  胡忠贵  王延奇  向娟 《岩石矿物学杂志》2010,29(2):199-205

塔里木盆地柯坪地区奥陶系发育浅水碳酸盐岩台地、深水陆棚-盆地两大类沉积体系和局限台地、开阔台地、陆棚和盆地等4种相类型。通过露头剖面的详细观察,在该区识别出局部暴露不整合和淹没不整合两类层序界面,以此为依据将该区奥陶系划分为9个三级层序。通过对层序格架内碳同位素和元素地球化学组成分析表明,不同层序界面及层序内不同体系域的δ13C和元素地球化学组成有明显的差异,并呈现出有规律性变化,反映出该区奥陶纪发生了多次海平面升降变化。研究表明同位素和地球化学特征可以作为层序地层学研究的辅助标志。  相似文献   

2.5维各向异性介质中多波波场正演模拟与波场分析     

苏云  李录明  唐娟 《物探与化探》2010,34(2)

完全3维弹性波数值模拟计算时间长,并且占用庞大的计算资源,这不利于在计算机配置不高的情况下进行科学研究,而二维弹性波数值模拟又达不到三维模拟的精度;同时,当模型、波场空间分布比较复杂时,传统的3维波动方程拟谱法模拟结果比较差.因此,在较高数值精度的一阶应力-速度弹性波动方程的基础上,采用傅氏变换仅计算y方向的偏导数,利用有限差分方法计算x、z方向和时间的偏导数,即利用2.5维数值模拟方法,实现在二维介质中计算三维弹性波场.最后通过数值模拟实现了在各向异性介质中多波波场的数值模拟,验证了2.5维方法是一种高精度、高效率、且能适应复杂模型的正演模拟方法,通过波场分析进一步认识了波在各向异性介质中的传播规律.  相似文献   

Speciation analysis of metals （Tl, Cd and Pb） in Tl-containing pyrite and its cinder from Yunfu Mine, China, by ICP-MS with sequential extraction   总被引：1，自引：0，他引：1  

Chunlin Wang  Yongheng Chen  Jianyang Pan  Ping Zhang  Jianying Qi  Juan Liu  Xiangping Li  Jin Wang 《中国地球化学学报》2010,29(1):113-119

The speciation of heavy metals such as thallium, cadmium and lead existing in pyrite and pyrite cinder was analyzed by ICP-MS with a sequential extraction procedure. The distribution patterns of these metals including exchangeable, reducible, oxidizable and residual fractions were obtained. Tl, Cd and Pb in pyrite and pyrite cinder samples from each extraction step were determined by inductively coupled plasma mass spectrometry (ICP-MS). Under the optimized instrumental conditions, detection limits of Tl, Cd and Pb in different matrices were within the range of 0.006–0.07 μg/L, and the relative standard deviations ranged from 0.8% to 1.2%. The accuracy of Tl, Cd and Pb determination was checked by analyzing two certified reference materials. The results demonstrate that trace Tl, Cd and Pb in the samples can be accurately determined. The sequential extraction results revealed that the percent contents of Tl, Cd and Pb in exchangeable, reducible and oxidizable fractions in pyrite cinder are different from those in pyrite and in pyrite cinder. Tl, Cd and Pb mostly are distributed in residual fraction. Therefore, the mobility of metals in pyrite is higher than that in pyrite cinder. Although distributions of Tl, Cd and Pb in the non-residual fraction are not dominant in pyrite cinder, the total concentrations of them could not be ignored. Consequently, attention must be paid to the risk of potential pollution by pyrite cinder.  相似文献   

遥感构造解译在秘鲁北部Chiclayo地区成矿预测中的应用   总被引：2，自引：0，他引：2       下载免费PDF全文

金文强  高光明  肖娟 《地质找矿论丛》2010,25(4):362-365,371

采用Landsat-7 ETM+数据制作的7-4-3波段假彩色合成图像,对秘鲁北部的奇克拉约(Chiclayo)地区进行了构造目视解译,共解译出15条线性构造和10个环形构造,结合地质特征和实地勘查资料,圈定了4个成矿预测区。  相似文献   

Intrinsic and specific vulnerability of groundwater in central Spain: the risk of nitrate pollution   总被引：5，自引：1，他引：4  

Juan J. Martínez-Bastida  Mercedes Arauzo  Maria Valladolid 《Hydrogeology Journal》2010,18(3):681-698

The intrinsic vulnerability of groundwater in the Comunidad de Madrid (central Spain) was evaluated using the DRASTIC and GOD indexes. Groundwater vulnerability to nitrate pollution was also assessed using the composite DRASTIC (CD) and nitrate vulnerability (NV) indexes. The utility of these methods was tested by analyzing the spatial distribution of nitrate concentrations in the different aquifers located in the study area: the Tertiary Detrital Aquifer, the Moor Limestone Aquifer, the Cretaceous Limestone Aquifer and the Quaternary Aquifer. Vulnerability maps based on these four indexes showed very similar results, identifying the Quaternary Aquifer and the lower sub-unit of the Moor Limestone Aquifer as deposits subjected to a high risk of nitrate pollution due to intensive agriculture. As far as the spatial distribution of groundwater nitrate concentrations is concerned, the NV index showed the greatest statistical significance (p?<?0.01). This new type of multiplicative model offers greater accuracy in estimations of specific vulnerability with respect to the real impact of each type of land use. The results of this study provide a basis on which to guide the designation of nitrate vulnerable zones in the Comunidad de Madrid, in line with European Union Directive 91/676/EEC.  相似文献   

Andalusite and Na- and Li-rich cordierite in the La Costa pluton, Sierras Pampeanas, Argentina: textural and chemical evidence for a magmatic origin     

Pablo H. Alasino  Juan A. Dahlquist  Carmen Galindo  Cesar Casquet  Julio Saavedra 《International Journal of Earth Sciences》2010,99(5):1051-1065

The La Costa pluton in the Sierra de Velasco (NW Argentina) consists of S-type granitoids that can be grouped into three igneous facies: the alkali-rich Santa Cruz facies (SCF, SiO₂ ~67 wt%) distinguished by the presence of andalusite and Na- and Li-rich cordierite (Na₂O = 1.55–1.77 wt% and Li₂O = 0.14–0.66 wt%), the Anillaco facies (SiO₂ ~74 wt%) with a significant proportion of Mn-rich garnet, and the Anjullón facies (SiO₂ ~75 wt%) with abundant albitic plagioclase. The petrography, mineral chemistry and whole-rock geochemistry of the SCF are compatible with magmatic crystallization of Na- and Li-rich cordierite, andalusite and muscovite from the peraluminous magma under moderate P–T conditions (~1.9 kbar and ca. 735°C). The high Li content of cordierite in the SCF is unusual for granitic rocks of intermediate composition.  相似文献   

U-Pb Zircon Geochronology with an Integrated LA-ICP-MS Microanalytical Workstation: Achievements in Precision and Accuracy   总被引：1，自引：0，他引：1  

Luigi A. Solari  Arturo Gómez-Tuena  Juan Pablo Bernal  Ofelia Pérez-Arvizu  Martin Tanner 《Geostandards and Geoanalytical Research》2010,34(1):5-18

Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) is a microanalytical tool especially suitable for providing fast and precise U-Pb geochronological results on zircon grains. A new 193 nm excimer laser adapted to a micromachining workstation, equipped with a newly designed two-volume ablation cell and coupled with a quadrupole ICP-MS, is presented here. The system was tuned routinely to achieve sensitivities in the range of 3000 cps/μg g⁻¹ for ²³⁸U (< 2% RSD), with a 34 μm spot size, at 5 Hz and ∼ 8 J cm⁻², while ablating the NIST SRM 612 glass reference material. The system was capable of providing fast (< 1.5 minutes each analysis) and precise (generally < 1.5% 1s errors) ²⁰⁶Pb/²³⁸U zircon ages. The ages of widely used reference material zircons (Plesovice, 337 Ma; Temora, 416 Ma; R33, 418 Ma; Sri Lanka, 564 Ma; 91500, 1065 Ma) could be precisely matched, with an accuracy on isotopic ratios that ranged from ∼ 2 to ∼ 6%, depending on the homogeneity of the natural reference materials.  相似文献