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1.
杜米芳 《岩矿测试》2008,27(2):146-148
通过选择分析谱线、处理样品方法和消除干扰因素等实验,建立了电感耦合等离子体发射光谱法同时测定玻璃中的Al2O3、CaO、Fe2O3、K2O、MgO、Na2O、TiO2和SO3的方法,克服了利用常规化学法测定玻璃中各氧化物步骤繁琐、耗时长、工作量大的不足。方法的回收率为95.0%~103.0%,精密度(RSD,n=10)为0.20%~1.72%。方法具有快速、简便、线性范围宽等优点,分析误差满足常规化学分析法的要求。用于钠钙硅玻璃及其制品的分析,结果令人满意。  相似文献   

2.
Lake Joyce is one of the least studied lakes of the McMurdo Dry Valleys. Similar to other lakes in this region, Lake Joyce is a closed-basin, permanently ice-covered, meromictic lake. We present here a detailed investigation of major ions, nutrients, and dissolved trace elements for Lake Joyce. Specifically, we investigate the role of iron and manganese oxides and hydrous oxides in trace metal cycling.Lake Joyce is characterized by fresh, oxic waters overlying an anoxic brine, primarily Na–Cl. Surface waters have a maximum nitrate concentration of 26M with a molar dissolved inorganic nitrogen to phosphorus ratio of 477. The supply of nitrogen is attributed to atmospheric deposition, possibly from polar stratospheric clouds. Dissolved phosphorus is scavenged by hydrous iron oxides. The pH is highest (10.15) just beneath the 7-m thick ice cover and decreases to a minimum of 7.29 in the redox transition zone. Dissolved Al exceeds 8M in surface waters, and appears to be controlled by equilibrium with gibbsite. In contrast, concentrations of other trace elements in surface waters are quite low (e.g., 5.4nM Cu, 0.19nM Co, <20pM La). Dissolved Fe, Mn, Ni and Cd were below our detection limits of 13 nM, 1. 8 nM, 4.7 nM and 15pM (respectively) in surface waters. There was a 6-m vertical separation in the onset of Mn and Fe reduction, with dissolved Mn appearing higher in the water column than Fe. Based on thermodynamic calculations, dissolved Mn appears to be controlled by equilibrium with hausmannite (Mn3O4). Co tracks the Mn profile closely, suggesting Co(III) is bound in the lattice of Mn oxides, whereas the Ce profile is similar, yet the Ce anomaly suggests oxidative scavenging of Ce. Release of Cu, Ni, Cd and trivalent REE appears to be controlled by pH-induced desorption from Fe and Mn oxides, although Cu (and perhaps Ni) may be scavenged by organic matter in surface waters.  相似文献   

3.
Oxide–sulphide–Fe–Mg–silicate and titanite–ilmenite textures as well as their mineral compositions have been studied in felsic and intermediate orthogneisses across an amphibolite (north) to granulite facies (south) traverse of lower Archean crust, Tamil Nadu, south India. Titanite is limited to the amphibolite facies terrane where it rims ilmenite or occurs as independent grains. Pyrite is widespread throughout the traverse increasing in abundance with increasing metamorphic grade. Pyrrhotite is confined to the high‐grade granulites. Ilmenite is widespread throughout the traverse increasing in abundance with increasing metamorphic grade and occurring primarily as hemo‐ilmenite in the high‐grade granulite facies rocks. Magnetite is widespread throughout the traverse and is commonly associated with ilmenite. It decreases in abundance with increasing metamorphic grade. In the granulite facies zone, reaction rims of magnetite + quartz occur along Fe–Mg silicate grain boundaries. Magnetite also commonly rims or is associated with pyrite. Both types of reaction rims represent an oxidation effect resulting from the partial subsolidus reduction of the hematite component in ilmenite to magnetite. This is confirmed by the presence of composite three oxide grains consisting of hematite, magnetite and ilmenite. Magnetite and magnetite–pyrite micro‐veins along silicate grain boundaries formed over a wide range of post‐peak metamorphic temperatures and pressures ranging from high‐grade SO2 to low‐grade H2S‐dominated conditions. Oxygen fugacities estimated from the orthopyroxene–magnetite–quartz, orthopyroxene–hematite–quartz, and magnetite–hematite buffers average 2.5 log units above QFM. It is proposed that the trends in mineral assemblages, textures and composition are the result of an external, infiltrating concentrated brine containing an oxidizing component such as CaSO4 during high‐grade metamorphism later acted upon by prograde and retrograde mineral reactions that do not involve an externally derived fluid phase.  相似文献   

4.
西藏泽当蛇绿岩位于雅鲁藏布江缝合带东段,由地幔橄榄岩、辉长岩、玄武岩等组成,地幔橄榄岩中发育有少量辉石岩、辉长岩、异剥钙榴岩、斜长花岗岩和角闪辉长岩。本文研究的角闪辉长岩侵入于泽当地幔橄榄岩的辉石岩中,主要由角闪石、葡萄石+绿纤石和少量Fe-Ti氧化物组成。岩石中角闪石呈自形,伟晶结构,褐色,均一的干涉色,与交代成因的角闪石相比具有较高的Al2O3(7.0%~11.0%)、Ti O2(1.0%~2.5%)和Na2O(1.0%~1.9%)含量,指示其为岩浆成因;Fe-Ti氧化物以磁铁矿为主(Ti O2=1.2%~13.2%;Fe2O3=40.6%~61.4%;Fe O=31.1%~43.6%),与钛铁矿(Ti O2=36.2%~50.8%;Fe2O3=2.5%~24.6%;Fe O=33.0%~43.7%)经常呈矿物对共生或出溶钛铁矿,磁铁矿—钛铁矿计算矿物平衡氧逸度(-logfo2)为12.4~22.8,约为NNO+1,比正常MORB氧化程度高,指示岩浆结晶时具有较高的水逸度。其锆石εHf(t)值为11.0~19.8,显示亏损地幔源区特征。岩石地球化学分析显示其具有高的Al2O3(20.4%~22.4%)、Ti O2(1.0%~1.5%),低的Mg O(4.1%~5.5%)含量类似高铝玄武岩的特征。泽当角闪辉长岩可能由亏损地幔部分熔融形成的含水岩浆经过演化(分离结晶作用等)形成的低镁高铝类似高铝玄武岩的岩浆结晶形成。然而样品严重亏损轻稀土(LREE),与常见于岛弧区的高铝玄武岩不同,可能为蛇纹石化的洋壳或地幔橄榄岩在俯冲早期脱水使得地幔楔发生部分熔融导致。对泽当蛇绿岩中侵入岩及地幔橄榄岩进行更详细的调查研究将对揭示泽当蛇绿岩的形成环境构造背景提供更多的线索。  相似文献   

5.
The Shevaroy Hills of northern Tamil Nadu, southern India, expose the highest-grade granulites of a prograde amphibolite facies to granulite facies deep-crustal section of Late Archaean age. These highly oxidized quartzofeldspathic garnet charnockites generally show minor high-TiO2 biotite and amphibole as the only hydrous minerals and are greatly depleted in the incompatible elements Rb and Th. Peak metamorphic temperatures (garnet–orthopyroxene) and pressures (garnet–orthopyroxene–plagioclase–quartz) are near 750 °C and 8 kbar, respectively. Pervasive veinlets of K-feldspar exist throughout dominant plagioclase in each sample and show clean contact with orthopyroxene. They are suggested to have been produced by a low H2O activity, migrating fluid phase under granulite facies conditions, most likely a concentrated chloride/carbonate brine with high alkali mobility accompanied by an immiscible CO2-rich fluid. Silicate, oxide and sulphide mineral assemblages record high oxygen fugacity. Pyroxenes in the felsic rocks have high Mg/(Mg+Fe) (0.5–0.7). The major oxide mineral is ilmenite with up to 60 mole per cent exsolved hematite. Utilizing three independent oxygen barometers (ferrosilite–magnetite–quartz, ferrosilite–hematite–quartz and magnetite–hematite) in conjunction with garnet–orthopyroxene exchange temperatures, samples with XIlmHm>0.1 yield a consistent oxygen fugacity about two log units above fayalite stability. Less oxidized samples (XIlmHm<0.1) show some scatter with indications of having equilibrated under more reducing conditions. Temperature-f (O2 ) arrays result in self consistent conditions ranging from 660 °C and 10?16 bar to 820 °C and 10?11.5 bar. These trends are confirmed by calculations based on the assemblage clinopyroxene–orthopyroxene–magnetite–ilmenite using the QUIlF program. In the most oxidized granulite samples (XIlmHm>0.4) pyrite is the dominant sulphide and pyrrhotite is absent. Pyrite grains in these samples have marginal alteration to magnetite along the rims, signifying a high-temperature oxidation event. Moderately oxidized samples (0.1no coexisting magnetite. Chalcopyrite is a common accessory mineral of pyrite and pyrrhotite in all the samples. Textures in some samples suggest that it formed as an exsolution product from pyrrhotite. Extensive vein networks of magnetite and pyrite, associated principally with the pyroxene and amphibole, give evidence for a pervasive, highly oxidizing fluid phase. Thermodynamic analysis of the assemblage pyrrhotite, pyrite and magnetite yields consistent high oxidation states at 700–800 °C and 8 kbar. The oxygen fugacity in our most oxidized pyrrhotite-bearing sample is 10?12.65 bar at 770 °C. There are strong indications that the Shevaroy Hills granulites recrystallized in the presence of an alkali-rich, low H2O-activity fluid, probably a concentrated brine. It cannot be demonstrated at present whether the high oxidation states were set by initially oxidized protoliths or effected by the postulated fluids. The high correspondence of maximally Rb-depleted samples with the highest recorded oxidation states suggests that the Rb depletion event coincided with the oxidation event, probably during breakdown of biotite to orthopyroxene+K-feldspar. We speculate that these alterations were effected by exhalations from deep-seated alkali basalts, which provided both heat and high oxygen fugacity, low aH2O fluids. It will be of interest to determine whether greatly Rb-depleted granulites in other Precambrian terranes show similar highly-oxidizing signatures.  相似文献   

6.
Coastal uses and other human activities have inevitably impinged on the Gulf environment; therefore, these regions require continuous monitoring. The investigated area covered the maximum fragments of Dubai coastal region in the Arabian Gulf. The determination of major oxides and trace metal concentrations in Dubai sediments revealed three heavily and moderately contaminated regions. One is in the far northeastern part at Al-Hamriya Sts 1–3 and contaminated by Fe, Cu, Pb, and Zn; the second is in the mid-northeastern part at Dry Docks and contaminated by Cu, Ni, Pb, and Zn; and finally, the third is in the near southwestern part at Dubal and contaminated by Fe, Mg, Cr, Ni, and Zn. Al-Hamriya St 3 represented the highest values of Cu, Pb, and Zn, whereas Dubal exhibited the maximum values of Fe, Mg, Ba, Cr, Mn, Ni, and V. The anthropogenic discharge and natural deposits are the main sources of contamination. In general, all trace and major elements showed the minimal levels at Jebel Ali Sanctuary (Sts 11, 12, 13) except for Sr and Ca, which showed their maximum values. The highest concentrations of Ca and Sr are mainly attributed to carbonate gravel sands and sands, which cover most stations. Each of V and Ni showed negative correlation with TPH, which may be indicated that the source of oil contamination in the region is not related to crude oil but mostly attributable to anthropogenic sources. The significant positive correlation, which was found between trace metals and TOC indicates that organic matter plays an important role in the accumulation of trace metals in case of Cu, Zn, and Pb.  相似文献   

7.
自然水体采集的生物膜上铁、锰氧化物的萃取分离   总被引：1，自引：0，他引：1  
采用选择性萃取分离技术对自然水体采集的生物膜上铁、锰氧化物进行萃取分离研究,考察该技术的适用性。参考人工培养生物膜的萃取方法,分别用NH2OH·HCl和Na2S2O4为萃取剂选择性萃取生物膜上的锰氧化物和铁、锰氧化物。实验中分别依次只改变萃取剂浓度、萃取液酸度或萃取时间,保持其它两个因素不变,分别考察这三个因素对萃取效果的影响,从中选出对铁、锰氧化物萃取率高而对有机质影响小的条件为最佳条件。用选定的最佳条件对不同时间和地点采集的生物膜进行萃取,发现对目的组分的萃取率可达70.8%~94.6%,而对非目的组分的影响很小（3.3%~11.0%）,满足萃取分离的要求。这说明选择性萃取技术可以广泛应用于自然水体采集的生物膜上铁、锰氧化物的萃取分离。  相似文献   

8.
周学粹  毛水和 《矿物学报》1989,9(3):257-261
未定名矿物(Ru,Fe)_2O_3产自我国西藏东巧超基性岩铬铂矿中。呈粒状、柱状、粒径8—42μm。具弱电磁性。与硫钌矿和等轴铁铂矿连生。反光下星灰黄色-灰白带棕色。双反射明显,强非均质性,有的呈3—10μm的微晶集合体。3个颗粒15个点的电子探针分析平均值(%):Ru 58.32,Fe 16.21,Os 2.71,Ir 1.78,O 20.97,矿物的化学式为(Ru,Fe)_2O_3。由于未能获X射线结构资料,暂未定名。  相似文献   

9.
根据对美国西部和我国东部一些岩体中钛铁氧化物的显微镜下统计测量和黑云母成分的电子探针分析结果,中性火成岩和Ⅰ型花岗岩中钛铁氧化物的平均粒度(S值)、分布密度(D值)和分布均匀度(H值)在一定程度上与岩浆成分及其结晶过程的物理化学条件(如温度、压力、水逸度、特别是氧逸度等)有关。据此,可将Ⅰ型花岗岩分为HD、MD、MLD和LD四种亚类。与斑岩铜矿及石英二长斑岩型斑岩钼矿有关的Ⅰ型花岗岩和与克莱麦克思型斑岩钼矿、斑岩钨矿和斑岩锡矿有关的Ⅰ型花岗岩二者的钛铁氧化物的S、D、H值亦有明显差别。  相似文献   

10.
Groundwater in some deep wells of Maydavood aquifer, southwestern Iran, contains relatively high concentrations of arsenic. Detailed hydrochemical analysis of these groundwaters (with ICP-OES instrument) showed that concentrations of iron, manganese, nickel, and vanadium are also high in them and concentrations of total arsenic in 81% of deep wells are greater than World Health Organization’s permissible value (10 ppb). XRF analysis of surrounding geological formations and aquifer sediments proposed that original source of arsenic in aquifer material can be attributed to minerals from Asmari Formation. It appears that a key mechanism for arsenic mobilizing to deep wells is microbial biodegradation of petroleum related organic matters (PROMs), which exist in aquifer sediments and originates from the bedrock of the aquifer (Gachsaran Formation). This process is followed by microbially mediated reductive dissolution of arsenic-bearing iron/manganese oxyhydroxides/oxides and further by nickel and vanadium mobilizing to groundwater. According to hydrogeochemical conditions and cluster analysis, water wells in Maydavood aquifer are divided to four subgroups: the wells with mildly reducing condition (subgroup I), moderately reducing condition (subgroup II), reducing condition (subgroup III), and high reducing condition (subgroup IV). Affected wells to arsenic are belonged to subgroups III and IV.  相似文献   

11.
东南极拉斯曼丘陵高级变质长英质岩石中铁钛氧化物的局部聚集与高级变质作用过程中的深熔作用有关,并非原岩富集这些组分。深熔作用造成惰性组分如铁钛氧化物滞留原地或略有聚集及活动性组分的迁移,而流体挥发组分优先聚集于熔体之中。当体系中水含量较低、处于不饱和状态时,深熔作用过程中形成局部"熔体",其结晶所成的浅色体不具低共结组分,没有熔体结晶结构,不是真正的熔体,可能是(准)熔体。较粗粒的浅色体或伟晶岩也是与深熔作用有关的产物,其形成早于花岗岩脉或岩体,而与花岗质岩浆分异无关。伴随(准)熔体的出现,体系中组分的萃取、分异效果较为明显,即可造成组分分异,形成截然不同的异地、二相分异结构,分别形成固相残留物(组成可以不固定)和(准)熔体相。固相残留体中富铝、铁组分,形成矽线石和铁钛氧化物团块,其中少或无挥发分;与此对应,短距离迁移浅色体中往往贫铁钛组分,可见石榴子石、偶见铁钛氧化物矿物。这种挥发分不饱和状态下的深熔作用基本属于封闭体系,整体失水不显著,高级变质岩中的一些特征矿物如矽线石、石榴子石、堇青石、尖晶石的形成也与这种分异作用有关,但组分迁移范围有限,并可保存组分分异各阶段的产物。拉斯曼丘陵长英质岩系中大量铁钛氧化物和矽线石类矿物组合的形成,反映了临界状态下的局部或差异抬升,变形作用的非均匀性及相伴随的组分分异作用,很可能相当于早期格林维尔期构造的泛非期再活动。   相似文献   

12.
We examined the relationship between soil oxidation capacity and extractable soil manganese, iron oxides, and other soil properties. The Korean soils examined in this study exhibited low to medium Cr oxidation capacities, oxidizing 0.00–0.47 mmol/kg, except for TG-4 soils, which had the highest capacity for oxidizing added Cr(III) [>1.01 mmol/kg of oxidized Cr(VI)]. TG and US soils, with high Mn contents, had relatively high oxidation capacities. The Mn amounts extracted by dithionite-citrate-bicarbonate (DCB) (Mnd), NH2OH·HCl (Mnh), and hydroquinone (Mnr) were generally very similar, except for the YS1 soils, and were well correlated. Only small proportions of either total Mn or DCB-extractable Mn were extracted by NH2OH·HCl and hydroquinone in the YS1 soils, suggesting inclusion of NH2OH·HCl and hydroquinone-resistant Mn oxides, because these extractants are weaker reductants than DCB. No Cr oxidation test results were closely related to total Mn concentrations, but Mnd, Mnh, and Mnr showed a relatively high correlation with the Cr tests (r = 0.655–0.851; P < 0.01). The concentrations of Mnd and Mnh were better correlated with the Cr oxidation tests than was the Mnr concentration, suggesting that the oxidation capacity of our soil samples can be better explained by Mnd and Mnh than by Mnr. The first component in principal components analysis indicated that extractable soil Mn was a main factor controlling net Cr oxidation in the soils. Total soil Mn, Fe oxides, and the clay fraction are crucial for predicting the mobility of pollutants and heavy metals in soils. The second principal component indicated that the presence of Fe oxides in soils had a significant relationship with the clay fraction and total Mn oxide, and was also related to heavy-metal concentrations (Zn, Cd, and Cu, but not Pb).  相似文献   

13.
The Homrit Akarem granitic intrusion (HAGI) outcrops near the western edge of the south Eastern Desert basement exposure in Egypt. It is a composite of two cogenetic intrusive bodies: an early albite granite phase shallowly emplaced at the apex of a magmatic cupola, and a later subjacent pink granite phase with a marginal zone of muscovite granite and better preservation of magmatic features. Mineral chemistry of primary biotite and garnet, together with whole-rock chemistry, identify the HAGI as a highly fractionated A-type peraluminous intrusion. The chemistry of F-dominant, Li-bearing, Fe3+-rich primary magmatic mica in the pink granite resembles that typically found in highly evolved Nb-Y-F pegmatites. The HAGI is the evolved product of a primary magma generated by partial melting of juvenile crust of the Arabian-Nubian Shield (ANS), emplaced along a regional strike-slip fault system that promoted its ascent. The main emplacement mechanism and evolutionary sequence of the HAGI was magmatic, although secondary minerals and textures resulting from hydrothermal fluid interactions are observed, especially at its margins. Primary columbite-(Mn) crystallized from melt and was partly replaced by secondary fluorcalciomicrolite. The high fluorine content of magmatic fluids exsolved from the intrusion is indicated by quartz-fluorite veins, greisenization, albitization, and F-bearing secondary oxide minerals. The magmatic derivation of this fluid is demonstrated by the F-dominant primary mica, a siderophyllite-polylithionite solid solution commonly known as zinnwaldite. The chemistry of zinnwaldite constrains the F/OH activity ratio and oxygen fugacity of its parental melt and thereby resolves the ambiguity between pressure and the effects of F in controlling the normative quartz content of rare-metal granites. The HAGI is less mineralized than the post-collisional rare-metal granites found further east in the south Eastern Desert, replicating a trend observed previously in the central Eastern Desert and suggesting that east-west zoning in rare metal enrichment is a persistent feature across latitudes at the western edge of the ANS.  相似文献   

14.
Hydrothermal Fe-Mn-Si oxides and nontronite are pervasive in the Hine Hina, Vai Lili and Mariner hydrothermal fields along the central Valu Fa Ridge, Lau Basin. Morphometric and mineralogical analyses reveal that the iron-rich filaments are the most important constituents of these Fe-Mn-Si oxide deposits. Both the morphologies and chemical composition of the filaments indicate that neutrophilic Fe-oxidizing bacteria have played a key role in the formation of these deposits. A key process of the formation of these deposits is the creation of a complicated filamentous network in which a series of metabolic activities and passive sorption and nucleation processes occur. The precipitation of dissolved Si in unsaturated and saturated states leads to a “two-generation” growth model in the hydrothermal vents. The precipitation of amorphous opal occurs in a relatively narrow temperature range (41.1-42.9 °C) based on oxygen isotope analyses, indicating a fast precipitation rate of opal-A when conductive cooling of the hydrothermal fluid occurrs. Patchy nontronite in the Mariner fields is a product of the direct precipitation from hydrothermal fluids at a temperature of ∼87.9 °C, whereas the scattered nontronite at the Hine Hina field is the product of the replacement of hydrothermal Fe-Si oxides at a temperature of ∼46.2 °C.  相似文献   

15.
To remediate Pb contaminated soils it is proposed that phosphorus can be amended to the soils to transform the Pb into poorly soluble Pb-phosphate mineral phases. However, remediation strategies must account for variable Pb speciation and site-specific factors. In this study soil mineralogy and Pb speciation in soils from P-amended field trials at sites within the Coeur d’Alene River Basin in Idaho, USA were investigated. The soils are contaminated from mining activities and are enriched with Fe and Mn. Selective extraction of the soils indicated that the Fe oxides are poorly crystalline. XRD of the soil clay size fractions identified quartz, muscovite, kaolinite, siderite, lepidocrocite, and chlorite minerals. Amendment with P fertilizer dissolved the siderite. No Pb–phosphate minerals were detected by XRD. Electron microprobe analysis showed direct correlations between Pb, Fe, and Mn in the unamended soils, and negative correlations between Pb and Si. Lead and Mn were strongly correlated. In the amended soils Fe and P were strongly correlated. Results indicate that the Pb is associated with poorly crystalline Fe and Mn oxides, and that added P is primarily associated with Fe oxide phases. Comparisons of pore water Pb concentrations with chloropyromorphite and plumbogummite solubility suggest that in the phosphate-amended soils the pore waters are undersaturated in these phases, whereas several of the control soil pore waters were oversaturated, indicating the added phosphate suppressed the Pb solubility. Results from this research provide insight into the geochemistry occurring in the P-remediated soils that will help in making management and remediation decisions.  相似文献   

16.
Michael D. Higgins   《Lithos》2005,83(3-4):199-213
The layered mafic intrusion at Sept Iles, Canada, is one of the largest intrusions in the world. A new interpretation of its structure is proposed, based on a review of its geology and a comparison with the Skaergaard intrusion, Greenland. Several different magmatic components are recognized; hence the name Sept Iles Intrusive suite (SIIS) is proposed. Emplacement of the suite may have been preceded by eruption of flood basalts. The first magmas of the suite rose in the crust to accumulate beneath the density filter afforded by the basalts. The largest component is the Sept Iles Mafic intrusion (SIMI). The Lower series of the SIMI is dominated by leucotroctolites and leucogabbros. Above it lie the Layered series, which is largely comprised of gabbro and troctolite. Both these units are unchanged from earlier interpretations. The anorthosites (s.l.), gabbros and monzogabbros, formerly called the Transitional series, are now considered to be the Upper Border series, developed by floatation of plagioclase. Common autoliths in the Layered series are parts of the hydrothermally altered Upper Border series from towards the interior of the intrusion, which have foundered and settled through the magma. The contamination of the magma that accompanied this event oxidised iron in the magma and led to the precipitation of magnetite around the periphery of the intrusion. The subsequent depletion of Fe3+ and/or increase in SiO2, CaO and P2O5 may have induced apatite saturation and accumulation to form two layers rich in apatite, near the base and at top of the Layered series. Granitic magma was developed by fractional crystallisation and was emplaced along the roof of the chamber, where it acquired large quantities of xenoliths. These were probably derived from the flood basalts, their evolved members and fragments of mafic dykes chilled by the granitic magma. Accumulations of monzonite pillows in this unit testify to another magmatic event and a floor to the granitic magma chamber, indicating lateral transport of magma. Chemically distinct syenites in the upper part of the intrusion are part of the Point du Criade intrusion, a large, late composite sill. Diabase and leucogabbro components show a close link with the SIMI and all the acidic magmas may have originally formed by differentiation of the main magma in cupolas towards the centre of the intrusion. A series of late gabbro intrusions that cut the SIMI may represent a rejuvenation of magmatism. The Border zone is a mass of fine-grained rocks that occurs along the border of the SIMI: it may be another magmatic component, or just the lateral border series of the SIMI.  相似文献   

17.
本文叙述了用沉淀抽滤法制备薄试样,X射线荧光光谱法测定混合稀土氧化物原料组分的分析方法。本法定量下限为0.01％—0.17％,方法精度为0.85％—14.9％。对几种类型的原料分析结果表明,本法与ICP-AES法结果基本相符。方法简便快速,可用于混合稀土氧化物原料的成分分析。  相似文献   

18.
激光熔蚀微量氧同位素分析方法及其地质应用   总被引：2，自引：1，他引：1  
高建飞  丁悌平 《地质论评》2008,54(1):135-144
研究小尺度或微区的同位素组成变化已成为地球化学分析技术发展的重要方向之一。在研制CO2激光熔蚀氧同位素制样装置的基础上,通过该装置与MAT253质谱计联机实现了硅酸盐和氧化物矿物的氧同位素在线分析。所测样品包括NBS28石英标样、石英玻璃,以及天然的石榴子石、锆石、橄榄石等一些难熔矿物。该装置分析的颗粒样品氧同位素分析精度为±022‰,最低样品量为8μmol的O2;石英玻璃原位分析的氧同位素分析精度为±035‰,最低样品量为7μmol的O2。这种装置和分析方法具备速度快,熔样温度高的特点,尤其适于难熔矿物。该装置可采用脉冲激光实现石英玻璃的微区原位分析,可应用于单个矿物生成环带的氧同位素研究。  相似文献   

19.
The Bizielle vein has some unique features among the Pyrenean alpine veins that allow us to address the question of the nature of iron oxides transformations under low temperature hydrothermal conditions, which is well known to prevailed over wide areas of western Europe between early Triassic to early Cretaceous times. Isotopic studies indicate a deep-seated origin of the ore-forming fluids and suggest that the metals were leached from the Variscan basement (mainly from granites). Isotopic geothermometry and regional evidences point to a 250 °C and reducing fluid, being SH2 the predominant S specie. Under such conditions, the proposed in situ deposition of hematite is a consequence of Fe carbonates dissolution and oxidation involving dissolution/precipitation processes in the sense of Putnis. Non-redox model is a quite plausible origin for subsequent hematite to magnetite conversion.  相似文献   

20.
Nanometric solid inclusions in diamond incorporated in garnet and zircon from felsic gneiss of the Kokchetav massif, Kazakhstan, have been examined utilizing electron microscopy and focused ion beam techniques. Host garnet and zircon contain numerous pockets of multiple inclusions, which consist of 1–3 diamond crystals intergrown with quartz, phengite, phlogopite, albite, K‐feldspar, rutile, apatite, titanite, biotite, chlorite and graphite in various combinations. Recalculation of the average chemical composition of the entrapped fluid represented by multiple inclusion pockets indicates that such fluid contained a low wt% of SiO2, suggesting a relatively low‐temperature fluid rather than a melt. Transmission electron microscopy revealed that the diamond contains abundant nanocrystalline inclusions of oxides, rare carbonates and silicates. Within the 15 diamond crystals studied, abundant inclusions were found of SiO2, TiO2, FexOy, Cr2O3, ZrSiO4, and single grains of ThxOy, BaSO4, MgCO3, FeCr2O4 and a stoichiometric Fe‐rich pyroxene. The diversity of trace elements within inclusions of essentially the same stoichiometry suggests that the Kokchetav diamond crystallized from a fluid containing variable amounts of Si, Fe, Ti, Cr, Zr, Ba, Mg and Th and other minor components such as K, Na, P, S, Pb, Zn, Nb, Al, Ca, Cl. Most of the components in crystals included in diamond appear to have their origin in the subducted metasediments, but some of them probably originate from the mantle. It is concluded that Kokchetav diamond most likely crystallized from a COH‐rich multicomponent supercritical fluid at a relatively low temperature (hence the apparently low content of rock‐forming elements), and that the diversity of major and minor components suggests interactions between subducted metasediments and mantle components.  相似文献   

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