Effects of size and origin of natural dissolved organic matter compounds on the redox cycling of iron in sunlit surface waters     

Laurence Meunier  Hansulrich Laubscher  Stephan J. Hug  Barbara Sulzberger 《Aquatic Sciences - Research Across Boundaries》2005,67(3):292-307

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Iron isotope fractionation during planetary differentiation   总被引：4，自引：0，他引：4  

Stefan Weyer  Ariel D. Anbar  Carsten Münker  Alan B. Woodland 《Earth and Planetary Science Letters》2005,240(2):251-264

The Fe isotope composition of samples from the Moon, Mars (SNC meteorites), HED parent body (eucrites), pallasites (metal and silicate) and the Earth's mantle were measured using high mass resolution MC-ICP-MS. These high precision measurements (δ⁵⁶Fe ≈ ± 0.04‰, 2 S.D.) place tight constraints on Fe isotope fractionation during planetary differentiation.Fractionation during planetary core formation is confined to < 0.1‰ for δ⁵⁶Fe by the indistinguishable Fe isotope composition of pallasite bulk metal (including sulfides and phosphides) and olivine separates. However, large isotopic variations (≈ 0.5‰) were observed among pallasite metal separates, varying systematically with the amounts of troilite, schreibersite, kamacite and taenite. Troilite generally has the lightest (δ⁵⁶Fe ≈ − 0.25‰) and schreibersite the heaviest (δ⁵⁶Fe ≈ + 0.2‰) Fe isotope composition. Taenite is heavier then kamacite. Therefore, these variations probably reflect Fe isotope fractionation during the late stage evolution and differentiation of the S- and P-rich metal melts, and during low-temperature kamacite exsolution, rather than fractionation during silicate-metal separation.Differentiation of the silicate portion of planets also seems to fractionate Fe isotopes. Notably, magmatic rocks (partial melts) are systematically isotopically heavier than their mantle protoliths. This is indicated by the mean of 11 terrestrial peridotite samples from different tectonic settings (δ⁵⁶Fe = + 0.015 ± 0.018‰), which is significantly lighter than the mean of terrestrial basalts (δ⁵⁶Fe = + 0.076 ± 0.029‰). We consider the peridotite mean to be the best estimate for the Fe isotope composition of the bulk silicate Earth, and probably also of bulk Earth. The terrestrial basaltic mean is in good agreement with the mean of the lunar samples (δ⁵⁶Fe = + 0.073 ± 0.019‰), excluding the high-Ti basalts. The high-Ti basalts display the heaviest Fe isotope composition of all rocks measured here (δ⁵⁶Fe ≈ + 0.2‰). This is interpreted as a fingerprint of the lunar magma ocean, which produced a very heterogeneous mantle, including the ilmenite-rich source regions of these basalts.Within uncertainties, samples from Mars (SNC meteorites), HED (eucrites) and the pallasites (average olivine + metal) have the same Fe isotope compositions as the Earth's mantle. This indicates that the solar system is very homogeneous in Fe isotopes. Its average δ⁵⁶Fe is very close to that of the IRMM-014 standard.  相似文献   

Elasticity of (Mg, Fe)(Si, Al)O₃-perovskite at high pressure     

Li Li  John P. Brodholt  Donald J. Weidner  Maria Alfredsson 《Earth and Planetary Science Letters》2005,240(2):529-536

The most abundant mineral on Earth has a perovskite crystal structure and a chemistry that is dominated by MgSiO₃ with the next most abundant cations probably being aluminum and ferric iron. The dearth of experimental elasticity data for this chemically complex mineral limits our ability to calculate model seismic velocities for the lower mantle. We have calculated the single crystal elastic moduli (c_ij) for (Mg, Fe^3 +)(Si, Al)O₃ perovskite using density functional theory in order to investigate the effect of chemical variations and spin state transitions of the Fe³⁺ ions. Considering the favored coupled substitution of Mg²⁺-Si^4 + by Fe³⁺-Al³⁺, we find that the effect of ferric iron on seismic properties is comparable with the same amount of ferrous iron. Ferric iron lowers the elastic moduli relative to the Al charge-coupled substitution. Substitution of Fe³⁺ for Al³⁺, giving rise to an Fe/Mg ratio of 6%, causes 1.8% lower longitudinal velocity and 2.5% lower shear velocity at ambient pressure and 1.1% lower longitudinal velocity and 1.8% lower shear velocity at 142 GPa. The spin state of the iron for this composition has a relatively small effect (< 0.5% variation) on both bulk modulus and shear modulus.  相似文献   

新疆哈密百灵山铁矿地质特征及成矿时代   总被引：2，自引：0，他引：2  

王龙生  李华芹  陈毓川  刘德权 《矿床地质》2005,24(3):264-269

文章总结了前人对百灵山铁矿的研究成果,并对已发表的地质图件进行了修正。首次对矿石中含矿石英脉中的流体包裹体进行了Rb_Sr等时线年龄测定,结果为(293±10)Ma,确定了该矿床的成矿时代为石炭纪末—二叠纪初。  相似文献   

石墨包覆纳米铁镍材料的制备及表征   总被引：1，自引：0，他引：1  

曹宏  王学华  宾晓蓓  陈理强  王家辉 《矿物学报》2005,25(1):75-80

碳包纳米磁性金属因其巨大的潜在应用前景成为了近年的研究热点，但现有各种方法都只能合成毫克量级样品。作者用金属钾还原镍铁氯化物石墨层间化合物合成了石墨碳网包覆纳米铁镍合金，一次至少可以得到几克样品。所合成样品成分分布比较均匀，w(Fe)=3．44％～9．67％，w(Ni)=0～2．95％。(Fe，Ni)纳米晶大小均匀，粒度因原料NiCl2-FeCl3GIGs阶数不同而异，2阶为5．7nm，3阶为17．1nm。样品具有表观超顺磁性。  相似文献   

X射线荧光光谱法测定多种铁矿和硅酸盐中主次量组分   总被引：3，自引：15，他引：3  

欧阳伦熬 《岩矿测试》2005,24(4):303-306

采用熔融玻璃法,用Axios型X射线荧光光谱仪测定铁矿和硅酸盐中Fe2O3、SiO2、A l2O3、TiO2、CaO、MgO、SO3、MnO、V2O5、K2O、P2O5、Na2O、Co和N i等组分含量。使用理论α系数和经验系数法校正基体效应,经标准物质检验,分析结果与标准值基本吻合。用钒钛磁铁矿GBW 07225国家一级标准物质进行精密度试验,统计结果除K2O、P2O5、N i的RSD<15%,其余大多数组分的RSD<4.0%(n=12)。  相似文献   

锰铁废渣作为道路基层填料的试验研究     

张向东  贾宝新 《中国地质灾害与防治学报》2005,16(1):106-109

现代工业迅猛发展的同时，也随之产生大量的工业废渣。利用工业废渣修筑道路基层，既可以达到道路基层的强度标准，也可以解决大量废渣的处理问题，具有十分重要的现实意义。论文对锰铁废渣的化学成份进行了分析，对风积土的物理力学性质进行了试验研究，获得了大量的科学数据。同时利用石灰、锰铁废渣、碎石和风积砂土作为路面基层稳定土的原材料，进行了配比试验和性能测试。在试验过程中，运用均匀设计方法安排试验，测量稳定土的各项指标。依据试验结果，采用SPSS软件进行了回归分析，得到了稳定土无侧限抗压强度的回归方程。试验结果表明，利用锰铁废渣作为道路基层的填料是可行的，既可以节约原材料的能量消耗，又可以减少环境污染，具有广泛的应用前景和显著的社会效益、环境效益与经济效益。  相似文献   

我国太古宙条带状铁矿研究进展及展望   总被引：5，自引：0，他引：5  

周世泰 《地质与勘探》1997,33(3):1-7

论述了中国太古宙条带状铁矿的调查研究史,以及这种类型铁矿床的矿石物质成分、变质岩、同位素地质年代学、成矿理论、弓长岭型富铁矿等方面的研究现状。指出了今后研究的主要方面。  相似文献   

新疆预须开普台铁铜矿床成因探讨   总被引：1，自引：1，他引：1  

莫江平  黄明扬 《地质与勘探》1997,33(4):7-12

根据矿床地质地球化学等方面的研究，认为该矿床成矿物质来源于深部地壳或上地幔；通过海底火山同流作用，在酸性相对还原的热学沉积盆地中沉积成矿。成矿流体来源岩浆水，并有海水混入。红碧玉、重晶石等具有喷流岩的特征。矿床成因属于海底火山喷流一热水沉积矿床。  相似文献   

矿产资源综合利用在我国铁矿石生产中的应用   总被引：2，自引：0，他引：2       下载免费PDF全文

李永徽 《地质找矿论丛》1997,12(4):65-72

根据矿资源现状及综合利用意义，扼要地对我国铁矿石资源综合利用所取得的选矿试验成果和生产中的应用进行了综述，对其今后发展前景进行了探讨。  相似文献