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1.
本文用Ｍｇ－Ｃｒ＾２＋橄榄石、辉石、尖晶石的粉晶Ｘ射线衍射数据，采取“整体图谱最小二乘Ｒｉｅｔｖｅｌｄ”方法计算了上述矿物的晶胞参数和摩尔体积，并对Ｃｒ＾２＋在各晶体结构中的占位情况进行了研究。结果显示，各矿物的晶胞参数随含Ｃｒ＾２＋量的增大而增大。据Ｖｅｇａｒｄ定律，推算出各端元组分铬橄榄石（ＣＦ２ＳｉＯ４）、铬辉石（Ｃｒ２ＳｉＯ２Ｏ６）及立方铬尖晶石（Ｃｒ３Ｏ４）的摩尔体积分别为４７．７，６８ 相似文献
2.
Cr^2＋在橄榄石,斜方辉石和尖晶石中溶解度的实验研究 总被引：1，自引：0，他引：1
为了研究Ｃｒ＾２＋在橄榄石、斜方辉石和尖晶石中的溶解度及其在各相间的分配，在压力为０－２．８８ＧＰａ和温度为１１００－１４５０℃的条件下，于ＭｇＯ－ＳｉＯ２－Ｃｒ－Ｏ体系中完成了一系列实验。实验起始成分由高纯度的ＭｇＯ、ＳｉＯ２、Ｃｒ２Ｏ３和Ｃｒ混合得到。通过Ｃｒ２Ｏ３和Ｃｒ等化学混合得到所需的ＣｒＯ，且加有过量（５０％）的Ｃｒ，使得实验产物和金属Ｃｒ保持平衡。此外，还加入占起始混合物重量１０％的 相似文献
3.
浙西石炭纪层状硅质岩地球化学特征及其意义 总被引：7，自引：0，他引：7
在浙西石炭纪地层中存在与地层整合产出的层状硅质岩。硅质岩中ＦｅＯ、ＭｎＯ、ＴｉＯ２、Ａｌ２Ｏ３、ＭｇＯ、ＣａＯ、Ｎａ２Ｏ、Ｋ２Ｏ等含量相对较高，富集Ａｓ、Ｓｂ、Ｂｉ、Ａｕ、Ａｇ、Ｇａ，Ｆｅ２Ｏ３／ＦｅＯ、ＳｉＯ２／Ａｌ２Ｏ３、ＳｉＯ２／（Ｎａ２Ｏ＋Ｋ２Ｏ）、ＳｉＯ２／ＭｇＯ比值较小，稀土元素总量低，Ｃｅ弱负异常，重稀土相对富集，包裹体富含气相组份ＣＨ４、ＣＯ２、Ｎ２、ＣＯ、Ｈ２，具热水沉积硅质岩的地球化学特征。在Ｆｅ—Ｍｎ—（Ｎｉ＋Ｃｏ＋Ｃｕ）三角图及ＳｉＯ２—Ａｌ２Ｏ３、ＳｉＯ２—Ｆｅ２Ｏ３图上均属于热水沉积硅质岩。硅质岩中硅、氧同位素也显示其热水成因之特点。硅质岩的硅同位素和稀土元素Ｃｅ／Ｃｅ※值表明本区层状硅质岩主要是在浅海环境下沉积的。硅质岩的形成温度较高，为９８℃～１５２℃ 相似文献
4.
华南下寒武统黑色岩系中的热水成因硅质岩 总被引：17，自引：2，他引：17
华南下寒武统黑色岩系Ｎｉ－Ｍｏ－ＰＧＥ序列富硫化物层上，下均出现在区域上延伸不甚稳定的硅质岩，过去对其成因未作研究。该硅质岩刘岫峰（１９９４）的化学成因，生物成因和火山成因硅质岩氧化物（ＳｉＯ２－Ａｌ２Ｏ３，ＳｉＯ２－ＭｇＯ，ＳｉＯ２－Ｋ２Ｏ＋Ｎａ２Ｏ）判别图解上多落在化学成因区和火山成因区，在Ｗｏｎｄｅｒ的热水成因和正常水成因硅质岩ＳｉＯ２－Ａｌ２Ｏ３判别图解上，多落在热水因区，该硅质岩稀土总量 相似文献
5.
研究了在氯化十六烷基吡啶（ＣＰＣ）和乳化剂ＯＰ存在下，Ｍｇ与邻氯苯基荧光酮（ｏ－Ｃｌ－ＰＦ）的显色反应。在ｐＨ１２的碱性介质中，Ｍｇ（Ⅱ）与ｏ－Ｃｌ－ＰＦ形成１：３的蓝色配合物，其λ＿ｍａｘ＝６１２ｎｍ，表现摩尔吸光系数ε＿６１２＝１．３９×１０￣５Ｌ·ｍｏｌ￣－１·ｃｍ￣－１，Ｍｇ（Ⅱ）在０～０．２μｇ／ｍｌ范围内符合比尔定律。方法用于新陶瓷材料氮化硅（Ｓｉ＿３Ｎ＿４）中微量ＭｇＯ的测定，其结果与原子吸收光谱法相符。 相似文献
6.
在温度为１１３０－１４５０℃，压力为０．４－２．０ＧＰａ条件下，实验研究了地幔橄榄岩部分熔融及相转变（尖晶石相→斜长石相）过程中的固相化学成分演变。在部分熔融中，随熔融度的增大，橄榄石的Ｍｇ／（Ｍｇ＋Ｆｅ）＾尖晶石和斜方辉石的Ｍｇ／（Ｍｇ＋Ｆｅ）及Ｃｒ／（Ｃｒ＋Ａｌ）逐渐增大；而橄榄石中的Ｃａ含量增至单斜辉石消失后逐渐降低；尖晶石中的Ｔｉ以较低的含量（ＴｉＯ２〈０．１５％）保持不变或稍有降低；斜方 相似文献
7.
锇粉中杂质元素分析方法研究 总被引：2，自引：0，他引：2
利用ＩＣＰ＿ＭＳ技术建立了锇粉中痕量杂质元素的分析方法。在浓ＨＮＯ３介质中，锇以ＯｓＯ４形式挥发除去，分离锇基体后，可直接测定的痕量元素达５０余种。取样量０．１ｇ，测定限为０．２～２４６ｎｇ／ｇ，可实现质量分数ｗ（Ｏｓ）为９９．９９９９％锇粉中杂质元素测定。结合ＩＣＰ＿ＡＥＳ测定Ｋ、Ｎａ、Ｃａ、Ｍｇ、Ａｌ、Ｆｅ、Ｓｉ和Ｐ，可实现锇粉原料及产品的纯度分析。 相似文献
8.
在西藏境内喜马拉雅山脉的东端的南迦巴瓦峰地区发现了星叶石。该矿物产出于火成碳酸岩脉中，与白云石、方解石、镁橄榄石、镁铝尖晶石、金云母、韭闪石、磷灰石、镁钛矿、石榴石以及三种未定名副矿物共生。该矿物的晶胞参数为：ａ０＝５．３５６（１），ｂ０＝１１．６０７（４），ｃ０＝１１．８５１（６），α＝６４．５７°（３），β＝７６．９８°（４），γ＝８５．４５°（３）。化学成分（％）为：ＳｉＯ２３５．２２，ＴｉＯ２１１．４７，Ａｌ２Ｏ３１．１８，ＦｅＯ２８．９０，ＭｎＯ５．１５，ＭｇＯ１．５１，ＣａＯ１．７５，Ｋ２Ｏ５．９０，Ｎａ２Ｏ２．４６，总和９３．５４％，化学式为：（Ｋ，Ｎａ）３（Ｆｅ，Ｍｎ，Ｍｇ，Ｃａ）７Ｔｉ２Ｓｉ８Ｏ２４（Ｏ，ＯＨ）７。 相似文献
9.
对Ｐ５０７萃淋树脂分离稀土元素的条件进行了实验，拟定了以Ｐ５０７萃淋树脂为固定相，ＨＣｌ为流动相分离４Ｎ级荧光材料Ｅｕ＿２Ｏ＿３中１４种稀土杂质元素的流程，使被测杂质与基体Ｅｕ＿２Ｏ＿３达到了较好的分离；再用阳离子交换树脂分离被测液中非稀土杂质元素。选择了端视ＩＣＰ－ＡＥＳ测量稀土杂质元素的最佳条件。称样量５０ｍｇ时各杂质组分的测定下限（ｕｇ／ｇ）为：ＣｅＯ＿２、Ｐｒ＿６Ｏ＿（１１）、Ｎｄ＿２Ｏ＿３、Ｓｍ＿２Ｏ＿３、Ｔｂ＿４Ｏ＿７、Ｈｏ＿２Ｏ＿３、Ｅｒ＿２Ｏ＿３，Ｔｍ＿２Ｏ＿３、Ｌｕ＿２Ｏ＿３０．４，Ｌａ＿２Ｏ＿３、Ｇｄ＿２Ｏ＿３、０．２，Ｄｙ＿２Ｏ＿３、Ｙ＿２Ｏ＿３０．０４，Ｙｂ＿２Ｏ＿３０．０２。６次取样分析，各杂质组分加入量为１０ｕｇ／ｇ（ＣｅＯ＿２为２ｕｇ／ｇ），加入回收率在８４％～１１２％；ＲＳＤ＜１３％。方法可用于纯度在９９．９９％～９９．９９９５％Ｅｕ＿２Ｏ＿３中１４种稀土杂质元素的测定。 相似文献
10.
地幔岩包体中斜方辉石的GOD化现象 总被引：2，自引：2，他引：2
对我国东部四个地点碱性玄武岩中地幔岩样品的研究分析表明，地幔岩包体被带上来的过程中，斜方辉石比单斜辉石更易发生部分熔融，而形成熔体玻璃（Ｇｌａｓｓ）、橄榄石（Ｏｌｉｖｉｎｅ）和铬透辉石（ＣｈｒｏｍｅＤｉｐｓｉｄｅ）集合体，此作用可称为ＧＯＤ化。ＧＯＤ化沿包体边部最发育，向内逐渐减弱，以至消失。当玻璃极富Ｋ２Ｏ时，出现强烈ＧＯＤ化。在强烈ＧＯＤ化外面的寄主岩石中，还形成销沸石和／或方沸石聚集体。斜方辉石的ＧＯＤ化不仅是由于升温降压而导致的不一致熔融所致，而且还伴有物质的交换（带入ＣａＯ＋Ｎａ２Ｏ＋Ｋ２Ｏ，带出ＳｉＯ２＋ＭｇＯ）。 相似文献
11.
12.
Yastami Oka Petra Steinke Niranjan D. Chatterjee 《Contributions to Mineralogy and Petrology》1984,87(2):196-204
Three Al-Cr exchange isotherms at 1,250°, 1,050°, and 796° between Mg(Al, Cr)2O4 spinel and (Al, Cr)2O3 corundum crystalline solutions have been studied experimentally at 25 kbar pressure. Starting from gels of suitable bulk
compositions, close approach to equilibrium has been demonstrated in each case by time studies.
Using the equation of state for (Al, Cr)2O3 crystalline solution (Chatterjee et al. 1982a) and assuming that the Mg(Al, Cr)2O4 can be treated in terms of the asymmetric Margules relation, the exchange isotherms were solved for Δ G
*,
and
. The best constrained data set from the 1,250° C isotherm clearly shows that the latter two quantities do not overlap within
three standard deviations, justifying the choice of asymmetric Margules relation for describing the excess mixing properties
of Mg(Al, Cr)2O4 spinels. Based on these experiments, the following polybaric-polythermal equation of state can be formulated:
, P expressed in bars, T in K, G
m
ex
and W
G,i
Sp
in joules/mol.
Temperature-dependence of G
m
ex
is best constrained in the range 796–1,250° C; extrapolation beyond that range would have to be done with caution. Such extrapolation
to lower temperature shows tentatively that at 1 bar pressure the critical temperature, T
c, of the spinel solvus is 427° C, with dTc/dP≈1.3 K/kbar. The critical composition, X
c, is 0.42
, and changes barely with pressure.
Substantial error in calculated phase diagrams will result if the significant positive deviation from ideality is ignored
for Al-Cr mixing in such spinels. 相似文献
13.
采用X射线衍射技术(XRD)对水镁石原矿和不同工艺条件生产的出口镁砂产品进行了物相组成分析,水镁石原矿粉中主相Mg(OH)2含量达到85.9%,杂质主要是Mg3Si2(OH)4O5、CaCO3和CaMg(CO3)2;轻烧镁砂中的Mg(OH)2大部分已经分解为MgO,但还有12.3%的Mg(OH)2未分解,并在低温煅烧的情况下生成了微量的新相Mg2SiO4;重烧镁砂中的Mg(OH)2已经完全分解为MgO,杂质主要存在形式是Mg2SiO4和CaCO3,占总量的18.5%。实验结果将成为提高水镁石矿煅烧生产的镁砂品质而改进提纯工艺的参考依据。 相似文献
14.
A thermochemical data base for phases in the system Fe-Mg-Si-O at high pressures up to 300 kbar is established by supplementing the available calorimetric data with data calculated from experimental high pressure synthesis studies. Phases included in the data base are the SiO2 polymorphs, rock salt solid solutions (Fe-Mg-O), Fe2O3, Fe3O4, (Mg, Fe)2SiO4 olivine, spinel, modified spinel and (Mg, Fe)SiO3 perovskite and pyroxene. Phases not included are the MgSiO3-ilmenite and -garnet. Fe-Mg solution properties of olivine, spinel, perovskite and wustite (rock salt) are estimated. The wüstite solid solution has been modeled as a nonideal solution of three end members; FeO, FeO1.5 and MgO. The new data base is made consistent with most of the available information on high pressure phase studies. The data base is useful in generating phase diagrams of various different compositions for the purpose of planning new experiments and analysing existing phase synthesis data. 相似文献
15.
Using recent additions to thermochemical data on minerals and information on their solid solution behavior, new equilibrium phase diagrams have been computed in a system of solar gas composition (Si, Al, Mg, Ca, Fe, Ni, Ti, Na, K, C, H, O, S, N) in the pressure and temperature ranges of 1 to 10?6 bar and 1153 to 1773 K respectively. These calculations show that Fe-Ni alloy condenses before all silicates included here (except melilite) down to a pressure of 2 · 10?4 bar below which plagioclase and clinopyroxene condense first. Orthopyroxene condenses next followed by ilmenite. Pressure-temperature variation of the chemical composition of melilite, clinopyroxene, orthopyroxene, metal alloy and plagioclase may be used for cosmothermometry and cosmobarometry for equilibrium assemblages.The major transition from the refractory oxides and melilite (the meteorite ‘inclusion assemblage’) to an assemblage of Fe-Ni alloy, olivine, plagioclase and pyroxenes (‘planet-forming’) takes place within a narrow interval of pressure and temperature. Small fluctuations of either pressure or temperature across this narrow region result in drastic changes in types and modes of minerals, which may explain the wide mineralogical varieties of meteorites. 相似文献
16.
The finding of ilmenite rods in olivine from orogenic peridotites has sparked a discussion about the processes of incorporation and exsolution of titanium in olivine. We have experimentally investigated the solubility of Ti in olivine as a function of composition, temperature and pressure in the synthetic TiO2–MgO–SiO2 system. Experiments at atmospheric pressure in the temperature range 1,200–1,500°C showed that the highest concentration of TiO2 is obtained when olivine coexists with spinel (Mg2TiO4). The amount of TiO2 in olivine in the assemblages olivine + spinel + periclase and olivine + spinel + ilmenite at 1,500°C was 1.25 wt.%. Changes in the coexisting phases and decreasing temperature result in a significant reduction of the Ti solubility. Olivine coexisting with pseudobrookite (MgTi2O5) and a Ti–Si-rich melt at 1,500°C displays a fourfold lower TiO2 content than when buffered with spinel. A similar decrease in solubility is obtained by a decrease in temperature to 1,200°C. There is a negative correlation between Ti and Si and no correlation between Ti and Mg in Ti-bearing olivine. Together with the established phase relations this suggests that there is a direct substitution of Ti for Si at these temperatures, such that the substituting component has the stoichiometry Mg2TiO4. The unit cell volume of olivine increases systematically with increasing TiO2 content demonstrating that the measured TiO2 contents in olivine are not caused by micro-inclusions but by incorporation of Ti in the olivine structure. Least squares fitting of 20 olivine unit cell volumes against the Ti content yield the relation: V (Å3)=290.12(1) + 23.67(85) NTi. The partial molar volume of end-member Mg2TiO4 olivine (NTi=1) is thus 47.24±0.13 cm3. The change of the Ti solubilty in olivine coexistent with rutile and orthopyroxene with pressure was investigated by piston cylinder experiments at 1,400°C from 15 to 55 kbar. There is no increase in TiO2 contents with pressure and in all the experiments olivine contains ~0.2 wt.% TiO2. Moreover, a thermodynamic analysis indicates that Ti contents of olivine coexisting with rutile and orthopyroxene should decrease rather than increase with increasing pressure. These data indicate that the ilmenite exsolution observed in some natural olivine does not signify an ultra-deep origin of peridotite massifs. 相似文献
17.
《International Geology Review》2012,54(15):1940-1974
Experimental synthesis of spinel peridotite phase assemblages for a range of compositions that mimic natural samples is used to derive a set of empirical geothermometers and geothermobarometers represented by multiple linear regression best-fit surfaces that link the variables of temperature, pressure, and composition. The calibrated geothermometers use reactions that govern the solubility of Al and Cr in both pyroxenes and the Mg–Fe exchange between silicates and spinel. Geothermobarometers map the Mg–Fe exchange between coexisting olivine and clinopyroxene and pyroxenes and Ca–Mg exchange between coexisting pyroxenes. Application of the geothermometers and geothermobarometers to suites of naturally occurring samples indicates that while reactions governing the Cr and Al solubility and solvus of orthopyroxene give useful estimates of ‘original’ mantle temperatures and pressures, respectively, comparable reactions for clinopyroxene yield estimates that are variably dependent on the transport phase of the sample suites. Temperature and pressure estimates from reactions governing Mg and Fe exchange between silicates and spinel and coexisting silicates are all sensitive to the later transport stage of the samples. 相似文献
18.
Diffusion of Al in synthetic forsterite was studied at atmospheric pressure from 1100 to 1500 °C in air along [100] with activities of SiO2, MgO and Al2O3 (aSiO2, aMgO and aAl2O3) buffered. At low aSiO2, the buffer was forsterite + spinel + periclase (fo + sp + per) at all temperatures, while at high aSiO2 and subsolidus conditions a variety of three-phase assemblages containing forsterite and two other phases from spinel, cordierite, protoenstatite or sapphirine were used at 1100–1350 °C. Experiments at high aSiO2 and 1400 °C used forsterite + protoenstatite + melt (fo + en + melt), and at 1500 °C, fo + melt. The resulting diffusion profiles were analysed by LA–ICP–MS in scanning mode. Diffusion profiles in the high aSiO2 experiments were generally several hundred microns in length, but diffusion at low aSiO2 was three orders of magnitude slower than in high aSiO2 experiments carried out at the same temperature, producing short profiles only a few microns in length and close to the spatial resolution of the analytical method. Interface concentrations of Al in the forsterite, obtained by extrapolating the diffusion profiles to the crystal/buffer interface, were only a fraction of those expected at equilibrium, and varied among the differing buffer assemblages according to (aAl2O3)1/2 and (aSiO2)3/4, pointing to the substitution of Al in forsterite by an octahedral-site, vacancy-coupled (OSVC) component with the stoichiometry Al 4/3 3+ vac2/3SiO4, whereas the main substitution expected from previous equilibrium studies would be the coupled substitution of 2 Al for Mg + Si, giving the stoichiometry MgAl2O4. It is proposed that this latter substitution is not seen on the length scales of the present experiments because it requires replacement of Si by Al on tetrahedral sites, and is accordingly rate-limited by the slow diffusivity of Si. Instead, diffusion of Al by the OSVC mechanism is relatively fast, and at high aSiO2, even faster than Fe–Mg interdiffusion. 相似文献
19.
《矿物学报》2013,(Z1)
Nepheline syenite is an important potassium-rich rock resource. Nepheline syenite powder was decomposed successfully by hydrothermal reaction using NaOH additive. Hydroxycancrinite (Na8(Al6Si6O24)(OH)2·2H2O ) solid and (K,Na)2SiO3 solution was obtained as a result of the hydrothermal reaction. 相似文献
20.
In order to understand the role of aqueous fluid on the differentiation of the mantle, the compositions of aqueous fluids coexisting with mantle minerals were investigated in the system MgO-SiO2-H2O at pressures of 3 to 10 GPa and temperatures of 1000 to 1500°C with an MA8-type multianvil apparatus. Phase boundaries between the stability fields of forsterite + aqueous fluid, forsterite + enstatite + aqueous fluid, and enstatite + aqueous fluid were determined by varying the bulk composition at constant temperature and pressure. The composition of aqueous fluid coexisting with forsterite and enstatite can be defined by the intersection of these two phase boundaries. The solubility of silicate components in aqueous fluid coexisting with forsterite and enstatite increases with increasing pressure up to 8 GPa, from about 30 wt% at 3 GPa to about 70 wt% at 8 GPa. It becomes almost constant above 8 GPa. The Mg/Si weight ratio of these aqueous fluids is much higher than at low pressure (0.2 at 1.5 GPa) and almost constant (1.2) at pressures between 3 and 8 GPa. At 10 GPa, it becomes about 1.4. Aqueous fluid migrating upward through the mantle can therefore dissolve large amounts of silicates, leaving modified Mg/Si ratios of residual materials. It is suggested that the chemical stratification of Mg/Si in the Earth may have been formed as a result of aqueous fluid migration. 相似文献