Partial melting controls on the northwest Kyushu basalts from Saga-Futagoyama     

Hidehisa  Mashima 《Island Arc》2005,14(2):165-177

Abstract   The major element and compatible trace element compositions of the northwest Kyushu basalts (NWKBs) collected from Saga-Futagoyama were analyzed to examine the petrogenesis of these basalts. Although nepheline-normative alkaline basalts are not found in the basalts from Saga-Futagoyama, the Saga-Futagoyama basalts almost cover the major element variations of NWKBs. The basalts can be chemically divided into two groups: an Fe-poor group (IPG) and an Fe-rich group (IRG). The compositional variation of IPG basalts is essentially controlled by the partial melting of the source as suggested by the following: (i) bulk rock MgO, FeO and NiO compositions indicate that some IPG samples were equilibrated with mantle olivine; and (ii) correlations between Al₂O₃, CaO and MgO are consistent with those of experimental partial melts of peridotites. The inconsistent behaviors of the elements compatible with clinopyroxene (Cpx), such as V (Sc and Cu), preclude the significant role of the fractional crystallization of Cpx and spinel in IPG variation. IPG basalts have low Al and high Fe concentrations compared to the products of melting experiments involving peridotites and pyroxenites, suggesting that the IPG source would have a lithology and bulk rock composition different from those of typical peridotites and pyroxenites. IRG basalts have negative correlations between Fe₂O₃* and MgO, and between V and Fe₂O₃*/MgO, indicating that IRG basalts would have fractionated Cpx. However, the anomalously Fe-rich feature of IRG basalts compared with NWKBs collected from other areas suggests that the role of Cpx fractionation in NWKBs is minor. Relatively low melting temperatures would have principally caused the large chemical variation of NWKBs.  相似文献   

Energetic Particles Observed in the CUSP Region During a Storm Recovery Phase     

S. Y. Fu  Q. G. Zong  Z. Y. Pu  C. J. Xiao  A. Korth  P. Daly  H. Reme 《Surveys in Geophysics》2005,26(1-3):241-254

In this paper we report energetic ion behavior and its composition variations observed by the Cluster/RAPID instrument when the spacecraft was travelling in the high latitude magnetospheric boundary region on the day of the 31 March, 2001, strongest magnetic storm in the past 50 years. The Dst index reached −360 nT at about 09:00 UT. During its early recovery phase, large amounts of oxygen and helium ions were observed; the ratio of oxygen to hydrogen in the RAPID energy range reached as high as 250%, which suggests that the observed energetic particles might be of magnetospheric origin. The observations further show that enhanced energetic electron fluxes are confined in a very narrow region, while protons have occupied a larger region, and heavy ions have been observed in an even larger region. The flux of energetic electrons show a slight enhancement in a region where the magnetic field magnitude is around zero. These observed energetic ions could be quasi-trapped by the current sheet in the stagnation region of the cusp.  相似文献   

Hydrogeochemistry of karst underground waters at shallow depth in Guiyang City, Guizhou Province     

董志芬  朱立军吴攀沈峥  封志勇 《中国地球化学学报》2005,24(2):194-200

The aim of this study is to shed light on the hydrogeochemical characteristics of karst underground waters at shallow depth in Guiyang City, Guizhou Province with an emphasis on the geochemistry of major elements. Guiyang City bears abundant underground waters and it is also an important representative of the karst areas throughout the world. Ca^2 and Mg^2 are the dominant cations, accounting for 81% -99.7% of the total, and HCO3^- and SO4^2- are the dominant anions. Weathering of limestones and dolostones is the most important factor controlling the hydrogeochemistry of underground waters, and weathering of sulfate and evaporite rocks is less important. Moreover, the precipitation and human activities also have a definite influence on the hydrogeoehemistry of underground waters in the region studied.  相似文献   

Water soluble components of PM10 Chongqing, China   总被引：1，自引：0，他引：1  

Luo Qingquan  Xian Xuefu  Chen Gangcai  Yang Qinglin 《中国地球化学学报》2005,24(2):155-157

The concentrations of water soluble ions (Na⁺, NH₄ ⁺, K⁺, Mg²⁺, Ca²⁺, NO₃ ^-, Cl^-, and SO ₄ ^2- ) in PM₁₀ samples collected on cellulose filters by a medium-volume cascade impactor were determined, which were obtained from three kinds of areas in Chongqing: industrial area (Jiulongpo district), commercial and residential area (Jiangbei district) and background area (Jinyun Mountain in the Beibei district). The results showed that except for the background site, the annual average values of PM₁₀ are 23% – 61% higher than the national air quality standard (GradeII) (0.1 mg/m³), even that the value of the control site is still 20% higher than American standard (0.05 mg/m³). This implied that serious pollution of fine particles occurred in Chongqing. Nine kinds of soluble ions in water of PM₁₀ were analyzed by ion chromatography (IC) and the annual average concentrations follow the order of [SO ₄ ^2- ] > [NO³ _-] > [Cl^-] > [F^-], and [Ca²⁺] > [NH₄ ⁺] > [K⁺] > [Na⁺] > [Mg²⁺]. Their values were different in these areas: the industrial area > the commercial and living area > the control area. As for NH_{4 +}, K⁺, Ca²⁺, NO₃ ^- and SO ₄ ^2- , their seasonal average concentrations show a similar variation trend: the values in spring and fall were higher than those in summer and winter. The seasonal average concentrations of [Cl^-], [F^-], [Na⁺] and [Mg²⁺] are much lower than those of other ions. However, the concentrations of [Na⁺] changed more greatly in different seasons than those of the other three ions. Correlation coefficients showed that the three areas have been polluted by coal smoke and dust to different extents, while some local resources of pollution should be taken into consideration as well.  相似文献   

Ressi experimental catchment: Ecohydrological research in the Italian pre-Alps     

Giulia Zuecco  Chiara Marchina  Ylenia Gelmini  Anam Amin  H. J. van Meerveld  Daniele Penna  Marco Borga 《水文研究》2021,35(3):e14095

Ressi is a small (2.4 ha) forested catchment located in the Italian pre-Alps. The site became an experimental catchment to investigate the water fluxes in the soil–plant–atmosphere continuum and the impact of vegetation on runoff generation in 2012. The elevation of the catchment ranges from 598 to 721 m a.s.l. and the climate is humid temperate. The bedrock consists of rhyolites and dacites; the soil is a Cambisol. The catchment is covered by a dense forest, dominated by beech, chestnut, maple, and hazel trees. The field set up includes measurements of the rainfall in an open area, streamflow at the outlet, soil moisture at various depths and locations, and depth to water table in six piezometers at a 5- or 10-min interval. Samples of precipitation, stream water, shallow groundwater and soil water are collected monthly for tracer analysis (stable isotopes (²H and ¹⁸O), electrical conductivity and major ions), and during selected rainfall–runoff events to determine the contribution of the various sources to runoff. Since 2017, soil and plant water samples have been collected to determine the sources of tree transpiration. Data collected in the period 2012–2016 are publicly available. Data collection is ongoing, and the data set is expected to be updated on an annual basis to include the most recent measurements.  相似文献   

A catalogue of major and trace element data for Icelandic Holocene silicic tephra layers     

RH. H. Meara  TH. Thordarson  N. J. G. Pearce  C. Hayward  G. Larsen 《第四纪科学杂志》2020,35(1-2):122-142

Tephra layers with Icelandic provenance have been identified across the North Atlantic region in terrestrial, lacustrine, marine and glacial environments. These tephra layers are used as marker horizons in tephrochronology including climate studies, archaeology and environmental change. The major element chemistries of 19 proximally deposited Holocene Icelandic silicic tephra layers confirm that individual volcanic systems have unique geochemical signatures and that eruptions from the same system can often be distinguished. In addition, glass trace element chemistry highlights subtle geochemical variations between tephra layers which appear to have identical major element chemistry and thus allows for the identification of some, if not all, tephra layers previously considered identical in composition. This paper catalogues the compositional variation between the widespread Holocene Icelandic silicic tephra deposits.  相似文献   

Diel stream geochemistry,Taylor Valley,Antarctica     

Sarah K. Fortner  W. Berry Lyons  LeeAnn Munk 《水文研究》2013,27(3):394-404

Unlike temperate and polythermal proglacial streams, the proglacial streams in Taylor Valley (TV), Antarctica, are derived primarily from glacier surface melt with no subglacial or groundwater additions. Solute responses to flow reflect only the interaction of glacial meltwater with the valley floor surrounding the stream channel. We have investigated the major, minor and trace element 24‐h variations of two proglacial melt streams, Andersen Creek and Canada Stream, originating from the Canada Glacier in TV, Antarctica. Both streams exhibited diel mid‐austral summer diurnal flow variation, with maximum flow being more than 50 times the minimum flow. Dissolved (< 0.4 µm) major, minor and trace solute behaviors through diel periods were strongly controlled by the availability of readily solubilized material on the valley floor and hyporheic‐biological exchanges. Anderson Creek had generally greater solute concentrations than Canada Stream because of its greater receipt of eolian sediment. Andersen Creek also acquired greater solute concentrations in the rising limb of the hydrograph than the falling limb because of dissolution of eolian material at the surface of the stream channel coupled with minimal hyporheic‐biological exchange. Conversely, Canada Stream had less available eolian sediment, but a greater hyporheic‐biological exchange, which preferentially removed trace and major solutes in the rising limb and released them in the falling limb. Given the dynamic nature of discharge, eolian, and hyporheic‐biological processes, solute loads in TV streams are difficult to predict. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

土壤样品镉同位素分析中Cd与Sn有效分离方法的改进     

段桂玲  段瑞春  谭娟娟  顾涛  邵长生  路韬 《岩矿测试》2016,35(1):10-16

保证Cd的高回收率以及彻底的Sn干扰去除是获得精确镉同位素组成的前提,目前报道的多种Cd分离与纯化方法获得的Cd回收率有较大差异(42.6%~99.8%),且去除Sn干扰的效果也不同(去除率在87.8%~97.4%之间),Cd回收率和Sn去除率均不理想。本文对前人报道的分离方法进行对比实验,发现0.1 mol/L氢溴酸-0.5 mol/L硝酸是分离Cd和Sn的有效试剂,增加该组混合酸的用量可淋洗出样品中更多的Sn且不会损失Cd,当混合酸的淋洗用量增加至30 mL时,Sn的淋洗率达到99.8%以上,Cd的回收率亦达到99.0%±0.5%,可满足土壤样品镉同位素的测定要求。本工作为获得高精度的镉同位素组成奠定了基础,为研究土壤环境中镉的污染来源提供了技术手段。  相似文献   

无内标-多外标校正激光剥蚀等离子体质谱法测定磁铁矿微量元素组成   总被引：4，自引：2，他引：2  

孟郁苗  黄小文  高剑峰  戴智慧  漆亮 《岩矿测试》2016,35(6):585-594

激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)常用于磁铁矿原位微量元素分析,按照校正策略不同,主要分为内标法和无内标法。内标法需要用电子探针(EMPA)预先测定磁铁矿中内标元素Fe的含量,过程较繁琐,且待测元素含量会受到内标元素含量测定的影响。本文采用铁含量较高的玄武质玻璃BCR-2G、BIR-1G、BHVO-2G和GSE-1G作为外标,避免了内标元素含量的测定,建立了无内标-多外标校正LA-ICP-MS测定磁铁矿微量元素组成的分析方法。利用该方法测定了科马提岩玻璃GOR-128g和自然岩浆磁铁矿BC 28的微量元素组成以评估方法的可靠性。结果表明,科马提岩玻璃的测定结果与推荐值及前人内标法的测定值一致,多数元素的相对标准偏差RSD5%;自然岩浆磁铁矿的测定结果与推荐值相比,多数元素的RSD7%,低于前人内标法的RSD(15%)。由此说明无内标-多外标法可以实现富铁硅酸岩或磁铁矿微量元素含量的准确校正,克服了基体效应的影响。因此,无内标-多外标法是一种原位测定磁铁矿微量元素含量的快速、准确方法,具有一定的应用潜力。  相似文献   

思维导图方法的教学实践     

刘智敏  独知行  于胜文  韩晓冬 《测绘科学》2016,41(9):186-190

思维导图在国内外已有多项研究证明思维导图在促进学生创新思维发展上有作用。在测绘类学科的高校教学中引入思维导图这种学习和工作方法,用在测绘本科教学改革中的讲座责任制授课模式上,通过在测绘本科教学方法改革的需求分析、应用实践和学生调查统计,得出结论:思维导图用于测绘类高校教学中,有利于提高学生创新思辨和自主学习能力,有助于达到以"能力"为核心的测绘专业人才培养目标。  相似文献