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1.
赣南浅变质岩岩石地球化学特征及稀土成矿潜力研究 总被引：2，自引：1，他引：1
赣南地区浅变质岩系分布广泛,且风化壳发育,查明浅变质岩的岩石学及地球化学特征对分析离子吸附型稀土矿床的成矿潜力具有重要作用,而目前关于变质岩离子吸附型稀土矿的研究资料较少。本文对区内广泛发育的新元古代—寒武纪浅变质岩进行采样,通过岩相学、岩石地球化学等方法对赣南浅变质岩进行分类研究。结果表明:赣南浅变质岩时代跨度大,从青白口系至泥盆系以及少量侏罗系均有出露,以新元古代面积最广,主要类型有变砂岩类、变质凝灰岩类、板岩类、千枚岩类及片岩类。其中,变砂岩类和变质凝灰岩类的稀土含量高(∑REEs平均值分别为302μg/g和246μg/g),LREEs/HREEs=2.68~5.43,目前查明的稀土矿物主要为独居石和磷钇矿。区内变质凝灰岩类产出厚度较大,稀土含量较高,风化壳发育,是良好的离子吸附型稀土矿的成矿母岩类型。千枚岩类和片岩类的平均稀土含量(∑REEs224μg/g)次之,但由于岩石风化难度较大,形成稀土风化壳型矿体可能性偏低。本研究是对变质岩离子吸附型稀土矿成矿的初步探讨,旨在为今后进一步的研究和找矿工作提供基础资料和依据。 相似文献
2.
稀土元素是现代科技、新能源、特种制造的关键性材料, 以其不可替代性和稀缺性, 而备受关注, 很多国家将其列为关键资源或战略资源。地球化学是研究稀土分布和发现稀土矿床的有效方法。本文利用“化学地球”大科学计划获得的全国15个稀土元素地球化学基准数据以及“一带一路”的中蒙边境、中缅老越边境地区地球化学填图数据为基础, 阐述中国稀土地球化学背景和圈定远景区。获得全国岩石和汇水域沉积物15个稀土元素、轻稀土(ΣLREE)、重稀土(ΣHREE)和总稀土(ΣREE)背景值。全国岩石背景值分别为: ΣLREE 121 μg/g, ΣHREE 35.0 μg/g, ΣREE 157 μg/g, 轻重稀土比值为3.5。全国汇水域沉积物背景值分别为: ΣLREE 134.0 μg/g, ΣHREE 38.5 μg/g, 和ΣREE 173 μg/g, 轻重稀土比值为3.5。总体上汇水域沉积物与岩石一致, 但含量略高于岩石。全国共圈定稀土地球化学异常区35处, 其中有26处异常与已知稀土矿或稀土成矿带相吻合, 新发现稀土超富集中心的稀土异常9处, 分别位于内蒙白云鄂博以西的乌拉特中旗—乌拉特后旗、华南异常富集中心、松潘—甘孜—攀西地区、云南红河州—中越边境、三江南段—中缅边境、雅鲁藏布江东段、西藏札达地区、中塔边境、黔东正安—荔波地区。这些异常显示, 是具有寻找白云鄂博型、碱性岩型、离子吸附型、花岗伟晶岩型、磷块岩型和泥岩型稀土矿的有利地区。 相似文献
3.
X射线荧光光谱法测定稀土精矿中的稀土元素分量 总被引：1，自引：1，他引：0
氟碳铈矿、独居石、磷钇矿和风化壳淋积型稀土矿四种稀土精矿样品采用化学法预分离富集,X射线荧光光谱法测定样品中稀土元素和伴生的铀、钍元素含量,选择以硼酸盐为主的混合熔剂高温熔融制样,消除矿物间存在的矿物结构影响,通过加大熔剂稀释比降低元素间的基体效应,人工标准样品绘制标准曲线,用数学校正方法校正元素间的谱线重叠效应。对淋积型稀土矿样品重复测定12次,方法检出限为0.9～42.1μg/g,待测组分的相对标准偏差(RSD)均小于10%,测定结果与电感耦合等离子体质谱法的测定值基本吻合。此方法应用于国家一级标准物质稀土标准样品定值工作,检出限和精密度能够满足分析要求,报出数据被采用率达到100%。 相似文献
4.
《地学前缘》2017,(5):172-181
选择赣南典型稀土矿区,即寻乌(以轻稀土为代表)、安远(以中稀土为代表)和龙南(以重稀土为代表)为研究区域,于生产期和停产期(停产后半年)分别采集了矿区上游、矿区淋滤废水、矿区山泉水、生活用井水、近矿支流、矿区下游等地表水共90件,分析了溶解态稀土元素在离子吸附型稀土矿区周边地表水中的含量、空间分布特征及影响因素。结果表明:稀土矿的开采对矿区周边地表水中DREE含量影响较大。此外,水粒作用、区域地质背景与风化作用、水化学因素都是影响离子吸附型稀土矿区周边水体DREE行为的主要因素。矿区周边地表水中稀土含量高是我国离子吸附型稀土矿山开采引发的特殊问题。 相似文献
5.
内蒙某稀土-铌-铁矿床含稀土较高,以独立矿物形式存在的有独居石、各种稀土氟碳酸盐、稀土铌钛酸盐(包括易解石、黄绿石、褐铈铌矿和褐钇铌矿),稀土碳酸盐(已发现的有碳铈钠矿)和极少量的硅酸盐(如褐帘石)。此外还有相当量的稀土以类质同象存在于一些非稀土矿物中。本矿床有些稀土矿物的颗粒很细,含量又高,很难单体分离,此外,含稀土分散量的矿物又常连生和包裹这些微细的稀土矿物。用一般物理方法和岩矿手段无法使它们分开,更不能进行定量分析。因此,本文用化学方法分离和测定各类稀土矿物和 相似文献
6.
7.
稀土分组的测定是研究物质组成以及综合评价稀土矿物的依据之一。大部分的稀土工业矿物均系综合回收多种金属的原料,其化学成分的测定对于稀土资源的开发和利用有着很大的参考价值。钍的化学性质与稀土相似,常以类质同象置换进入稀土矿物中。几种主要的稀土工业矿物中钍的含量可达0.X～X％,甚或更高。因此,铈族稀土、钇族稀土和钍相互之间的分离和测定是稀土类矿物分析中的一个重要环节。 相似文献
8.
9.
磷块岩中通常伴生有稀土元素富集,是一种潜在、具有很高开发利用价值的稀土资源。我国磷块岩型稀土矿分布广、稀土含量高、具有综合回收价值,是仅次于独立稀土矿床的伴生稀土资源。通过统计全球及中国磷矿时空分布规律,总结中国典型磷块岩型稀土矿床的矿床成因、地质背景、沉积环境、岩石组合、REE地球化学特征。在此基础上,结合P_2O_5与ΣREE、δCe、δEu、MREE/ΣREE和MREE/LREE在各时代之间的对比及耦合关系,讨论各时代稀土配分模式,讨论磷块岩中稀土富集机制与控制因素问题,讨论中国典型磷块岩型稀土矿资源储量。同时总结国内对磷块岩中稀土高效、环保的提取技术,对工业化开发利用磷块岩中稀土资源具有良好的可行性。因此,从磷矿中提炼稀土资源可以获得很好的社会价值和经济效益,能有效缓解我国南方离子吸附型稀土开采带来的环境污染、生态破坏,为日益枯竭稀土资源提供新的资源途径。 相似文献
10.
南岭地区蕴藏着丰富的稀土资源,是我国稀土矿产的重要产地。南岭稀土矿的成矿,具有一些独特的特征。1.矿化类型多,质量好矿化类型按稀土成因特点划分,有内生型、外生型和变生型等三大类矿床;按矿化岩性划分,有花岗岩型、火山岩型、混合岩型、伟晶岩型、中基性脉岩型和砂矿等;按稀土赋存形式划分,有单矿物型和离子吸附型矿床;按稀土元素组合特征划分,有轻稀土、中稀土和重稀土三大类型。本区的稀土矿质量好,富含经济价值较高的中、重稀土元素,杂质含量低。 相似文献
11.
We studied the states of rare earth elements in ore of the Xianglushan rare earth deposit. Rare earth ore samples were tested and examined by scanning electron microscope, electron probe, and chemical leaching. No independent rare earth minerals were detected by scanning electron microscope. Elements detected by the electronic probe for the in situ micro-zone of the sample included: O, Al, Si, Ca, Mg, Fe, Ti, K, Na, S, Cl, C, Cu, Cr, V, and Pt. Rare earth elements were not detected by electron probe. (NH4)2SO4, (NH4)Cl, NaCl, and H2SO4 were used as reagents in chemical leaching experiments that easily leached out rare earth elements under the action of 10% reagent, indicating that the rare earth elements in ore are mainly in the ionic state rather than present as rare earth minerals. 相似文献
12.
巴尔哲超大型稀有稀土矿床成矿机制研究 总被引：9，自引：2，他引：7
巴尔哲矿床中的矿化和非矿化碱性花岗岩主要造岩矿物均为微斜长石、石英、钠闪石和钠长石,但其相对含量及颗粒大小明显不同,且两类岩石中包裹体的组成特征及锆石的结晶习性也有显著差异.主量元素分析显示,矿化与非矿化碱性花岗岩均以富硅、富碱、贫镁和钙为特征,为较典型的非造山A型花岗岩.尽管矿化碱性花岗岩中K_2O和Na_2O的含量均没有明显的增加,但其Na+K/Al、Na_2O+K_2O/CaO、FeO~*/MgO及K_2O/MgO等岩石化学参数与非矿化碱性花岗岩明显不同.在矿化碱性花岗岩中除了矿化的稀土元素及Nb、Zr强烈富集外,U、Th及Y也明显富集,而Ba、Sr、P、Eu和Ti表现为强烈的亏损.在非矿化碱性花岗岩中除了大离子亲石元素Rb略有富集外,稀土元素、Nb、Zr、U、Th、Ta及Y并无明显富集,虽然Sr、P、Eu和Ti也表现为亏损,但与矿化碱性花岗岩相比其亏损程度明显降低.岩相学、岩石化学及微量元素地球化学特征显示,矿化碱性花岗岩不可能是非矿化碱性花岗岩硅化和钠长石化作用的产物,二者应是同一岩浆体系不同演化阶段熔体固结的产物.K/Rb、Rb/Sr及δEu等地球化学参数显示,矿化碱性花岗岩是高演化A型花岗质熔体固结的产物;而岩石学、包裹体及地球化学特征则显示,这种高演化的A型花岗质熔体已经进入了岩浆一热液过渡阶段.巴尔哲矿床稀有稀土元素的超常富集和成矿与A型花岗岩的高演化过程密切相关. 相似文献
13.
R. D. Shannon T. E. Gier C. M. Foris J. A. Nelen D. E. Appelman 《Physics and Chemistry of Minerals》1980,5(3):245-253
Single crystal synthesis, X-ray powder diffraction data, and electron microprobe data are given for some Na rare earth silicates of the types NaMSiO4, Na3MSi2O7, Na3MSi3O9, and Na5MSi4O12. NaYSiO4 is orthorhombic with SG Pbn21, a=5.132, b=11.156, anc c=6.405 Å. NaGdSiO4 is tetragonal with SG I4 or I \(\bar 4\) with a=11.743 and c=5.444 Å. A second form of NaGdSiO4 is orthorhombic with SG P21 nb or Pmmb, a=9.179, b=27.29, and c=5.472 Å. Na3YSi2O7 is hexagonal with a=9.416 and c=13.776 Å. Na3YSi3O9 is orthorhombic with a=15.215, b=15.126, and c=15.036 Å. Na ion conductivities of Na3YSi2O7 and Na3YSi3O9 at 300° C of 5×10?6 (Θ-cm)?1 and 6×10?6 (Θ-cm)?1, respectively, are substantially less than that for Na6YSi4O12, 1×10?1 (Θ-cm)?1. 相似文献
14.
Geochemistry of rare earth elements in oceanic phillipsites 总被引：3，自引：0，他引：3
A. V. Dubinin 《Lithology and Mineral Resources》2000,35(2):101-108
The behavior of rare earth elements (REE) was examined in oceanic phillipsites collected from four horizons of eupelagic clay
in the Southern Basin of the Pacific. The REE concentrations were determined in the >50-μm-fraction phillipsite samples by
the ICP-MS method. The composition of separate phillipsite accretions was studied using the electron microprobe and secondary
ion mass-spectrometry. Rare earth elements in phillipsite-only samples are related to the admixture of ferrocalcium hydroxophosphates.
The analysis of separate phillipsite accretions reveals low (<0.1–18.1 ppm) REE (III) concentrations. The Ce concentration
varies between 2.7 and 140 ppm. The correlation analysis shows that REE (III) are present as an admixture of iron oxyhydroxides
in separate phillipsite accretions. Based on the REE (III) concentration in iron oxyhydroxides, we can identify two generations
of phillipsite accretions. Massive rounded accretions (phillipsite I) are depleted in REE, while pseudorhombic (phillipsite
II) accretions are enriched in REE and marked by a positive Ce anomaly. Oceanic phillipsites do not accumulate REE or inherit
the REE signature of the volcaniclastic material and oceanic deep water. Hence, the REE distribution in phillipsites does
not depend on the sedimentation rate and host sediment composition. 相似文献
15.
Pb and rare earth element diffusion in xenotime 总被引：1，自引：0，他引：1
Diffusion of Pb and the rare earth elements Sm, Dy and Yb have been characterized in synthetic xenotime under dry conditions. The synthetic xenotime was grown via a Na2CO3–MoO3 flux method. The sources of diffusant for the rare earth diffusion experiments were REE phosphate powders, with experiments run using sources containing a single REE. For Pb, the source consisted a mixture of YPO4 and PbTiO3. Experiments were performed by placing source and xenotime in Pt capsules, and annealing capsules in 1 atm furnaces for times ranging from 30 min to several weeks, at temperatures from 1000 to 1500 °C. The REE and Pb distributions in the xenotime were profiled by Rutherford Backscattering Spectrometry (RBS).The following Arrhenius relations are obtained for diffusion in xenotime, normal to (101):Diffusivities among the REE do not differ greatly in xenotime over the investigated temperature range, in contrast to findings for the REE in zircon [Cherniak, D.J., Hanchar, J.M., Watson, E.B., 1997. Rare earth diffusion in zircon. Chem. Geol. 134, 289–301.], where the LREE diffuse more slowly, and with higher activation energies for diffusion, than the heavier rare earths. In zircon, these differences among diffusion of the rare earths are attributed to the relatively large size of the REE with respect to Zr, for which they likely substitute in the zircon lattice. With the systematic increase in ionic radius from the heavy to lighter REE, this size mismatch becomes more pronounced and diffusivities of the LREE are as consequence slower. Although xenotime is isostructural with zircon, the REE are more closely matched in size to Y, so in xenotime this effect appears much smaller and the REE diffuse at similar rates. In addition, the process of diffusion in xenotime likely involves simple REE+ 3 → Y+ 3 exchange, without charge compensation as needed for REE+ 3 → Zr+ 4 exchange in zircon. This latter factor may also contribute to the large activation energies for diffusion of the REE in zircon (i.e., 691–841 kJ mol− 1, [Cherniak, D.J., Hanchar, J.M., Watson, E.B., 1997. Rare earth diffusion in zircon. Chem. Geol. 134, 289–301.]), in comparison with those for xenotime.For Pb, the following Arrhenius relation is obtained (also normal to (101)):These measurements suggest that Pb diffusion in xenotime is quite slow, even slower than Pb diffusion in monazite and zircon, and considerably slower than diffusion of the REE in xenotime. Xenotime may therefore be even more retentive of Pb isotope signatures than either monazite or zircon in cases where Pb isotopes are altered solely by volume diffusion. However, because the activation energy for Pb diffusion in xenotime is lower than those for monazite and zircon, Pb diffusion may be somewhat faster at many temperatures of geologic interest in xenotime than in monazite or zircon. 相似文献
16.
The ability of organic matter as well as carbonate ions to extract rare earth elements (REEs) from sandy sediments of a Coastal Plain aquifer was investigated for unpurified organic matter from different sources (i.e., Mississippi River natural organic matter, Aldrich humic acid, Nordic aquatic fulvic acid, Suwannee River fulvic acid, and Suwannee River natural organic matter) and for extraction solutions containing weak (i.e., CH3COO−) or strong (i.e., ) ligands. The experimental results indicate that, in the absence of strong REE complexing ligands in solution, the amount of REEs released from the sand is small and the fractionation pattern of the released REEs appears to be controlled by the surface stability constants for REE sorption with Fe(III) oxides/oxyhydroxides. In the presence of strong solution complexing ligands, however, the amount and the fractionation pattern of the released REEs reflect the strength and variation of the stability constants of the dominant aqueous REE species across the REE series. The varying amount of REEs extracted by the different organic matter employed in the experiments indicates that organic matter from different sources has different complexing capacity for REEs. However, the fractionation pattern of REEs extracted by the various organic matter used in our experiments is remarkable consistent, being independent of the source and the concentration of organic matter used, as well as solution pH. Because natural aquifer sand and unpurified organic matter were used in our experiments, our experimental conditions are more broadly similar to natural systems than many previous laboratory experiments of REE-humic complexation that employed purified humic substances. Our results suggest that the REE loading effect on REE-humic complexation is negligible in natural waters as more abundant metal cations (e.g., Fe, Al) out-compete REEs for strong binding sites on organic matter. More specifically, our results indicate that REE complexation with organic matter in natural waters is dominated by REE binding to weak sites on dissolved organic matter, which subsequently leads to a middle REE (MREE: Sm-Ho)-enriched fractionation pattern. The experiments also indicate that carbonate ions may effectively compete with fulvic acid in binding with dissolved REEs, but cannot out compete humic acids for REEs. Therefore, in natural waters where low molecular weight (LMW) dissolved organic carbon (DOC) is the predominant form of DOC (e.g., lower Mississippi River water), REEs occur as “truly” dissolved species by complexing with carbonate ions as well as FA, resulting in heavy REE (HREE: Er-Lu)-enriched shale-normalized fractionation patterns. Whereas, in natural terrestrial waters where REE speciation is dominated by organic complexes with high molecular weight DOC (e.g., “colloidal” HA), only MREE-enriched fractionation patterns will be observed because the more abundant, weak sites preferentially complex MREEs relative to HREEs and light REEs (LREEs: La-Nd). 相似文献
17.
In order to ascertain the forms in which uranium is present in ores of the Melovoe rare metal sedimentary deposit of uranium
and rare earth minerals (South Mangyshlak), we investigated a series of typical ore samples that were collected earlier; both
the uranium content and the total content of rare earth metals in them lay within 0.1–0.3%. The study was carried out by analytical
electron microscopy using transmission electron microscopy and scanning electron microscopy, electron microdiffraction, and
microprobing. It was ascertained that both uranium and rare earth elements are present in ore mostly associated with biogenic
phosphate in the form of natural minerals, such as uraninite, ningyoite, coffinite, autenite, and churchite. Iron hydroxides
and graphitized organic matter are present in some samples. It is assumed that the co-occurrence of uranium and rare earth
elements, which is nontypical for the sedimentary process, resulted from secondary epigenetic processes and alternation of
reducing and oxidizing environmental conditions. 相似文献
18.
Summary ?The occurrence of divalent rare earth elements (Sm2+, Yb2+, Tm2+, and Ho2+) in natural fluorite is evaluated using a suite of 37 samples deriving mainly from Sn–W deposits in the Erzgebirge (Germany),
Central Kazakhstan, and the Mongolian Altai. Trace element composition was determined by ICP-AES and ICP-MS. The defect structure
of the samples was studied by cathodoluminescence (CL), electron paramagnetic resonance (EPR), and optical absorption spectroscopy.
Reduction of cubic Sm3+, Yb3+, Tm3+, and Ho3+ under radioactive irradiation produces the corresponding divalent centres. Our data suggest a preferable formation of Sm2+ and Yb2+ under thorium and of Tm2+ and Ho2+ under uranium irradiation. Irradiation (indicated by intense brownish (thorium) and deep purple (uranium) coloration of fluorite)
gives rise to a population of divalent centres in equilibrium with their decay. However, sporadic radioactive irradiation
and stabilisation of the divalent state of the REE by other electron defects were found in most cases.
Three models of stabilisation of Sm2+, Yb2+, Tm2+, and Ho2+ are discussed. The most effective mechanism for Sm, Yb, Tm, and Ho is coupling with Fe3+ centres (REE3++Fe2+ → REE2++Fe3+). Accordingly, the occurrence of Fe3+ centres in natural fluorite is regarded to indicate not an oxidising, but rather a reducing environment during fluorite precipitation.
Originally incorporated in the divalent form, Fe2+ was converted to Fe3+ by radioactive irradiation. Such a conclusion is in agreement with the finding of high contents of interstitial fluorine
providing tetragonal local compensation of trivalent REE centres in crystals with high Fe3+. If Fe is not present, compensation of divalent Sm, Yb, and Tm is achieved by radiogenic oxidation of Ce(Pr, Tb)3+ accompanied by charge transfer (REE3++Ce(Pr, Tb)3+ → REE2++ Ce(Pr, Tb)4+). Ho2+ is sometimes stabilised by a hole trapped by an electron localised on a F vacancy (Ho3++e− on □F → REE2++ self-trapped exciton). Because Sm2+ is optically active, the stabilisation by Fe3+ (stable up to temperatures above 350 °C) or Ce(Pr, Tb)4+ (unstable even under visible light) in samples may be determined by careful observations in the field.
Institut für Geotechnik, ETH Zürich, ETH-H?nggerberg, Zürich, Switzerland
Stanford Linear Accelerator Center, Menlo Park, CA, USA
Received January 8, 2002; revised version accepted June 10, 2002 相似文献
19.
漳平永福稀土矿区位于闽西南坳陷带西南部广坪—龙岩复向斜东翼,政和—大埔大断裂西侧。区内成矿母岩为燕山早期第三阶段第三次侵入似斑状中粒黑云母花岗岩(永福岩体)。花岗岩岩体风化壳较发育,分布广,具有离子吸附型稀土矿的矿床地质特征、成矿条件以及稀土矿富集、成矿规律。 相似文献