苏北榴辉岩的稀土元素地球化学及其成因讨论

江苏北部的榴辉岩出露于东海群变质岩系中，榴辉岩的产状是：１）呈似层状或透镜状产于东海群片麻岩中；２）呈不规则团块状产于超镁铁岩中，或与超镁铁岩伴生。全岩分析表明，前者相当橄榄拉斑玄琥岩或石英拉斑玄武岩，后者相当橄榄玄武岩或橄榄拉斑玄武岩。     

ANC,BNC and mobilization of Cr from polluted sediments in function of pH changes

During the manufacturing of chromate salts (1972–1992) large quantities of Chromite Ore Processing Residue (COPR) were released into a decantation pond east of the former chemical plant of Porto-Romano (Durres, Albania), giving rise to yellow colored pond sediments. These Cr(VI) bearing sediments were deposited upon Quaternary silty-clay lagoonal sediments rich in iron oxides and organic matter. The pH values in these lagoonal sediments vary around 6.6, while in the pond sediments, it is mainly acidic (due to the presence of the sulfur stock piles in the area and the release of the H₂SO₄ from the activity of the former chemical plant), varying between 1.4 and 3.8. Continuous leaching of the COPR waste resulted in yellow-colored surface water runoff. The prediction of pH changes in the different types of sediments based upon acid/base neutralizing capacity (ANC/BNC) jointly with the quantitative data on release of heavy metals and especially Cr is considered an important advantage of the pH_stat leaching test if compared to conventional leaching procedures. Thus, factors controlling the leaching of Cr(VI), Cr(III), Ca, Al, Fe, Mg from the COPR were investigated by means of pH_stat batch leaching tests and mineralogical analysis. Moreover, mathematical and geochemical modeling complemented the study. The COPR in the area contain very high concentrations of chromium 24,409 mg/kg, which mainly occurs as Cr(III) (75–90%) as well as Cr(VI) (25–10%). The leaching of Cr(VI) occurs in all the range (2–10) of the tested pH values, however, it decreases under acidic conditions. Beside some reduction of Cr(VI) to Cr(III), the Cr(VI) content of the leachtes remains relatively high in the acidic environment, while the limning of Cr(VI) pond sediments will increase the release of the latter specie. The leaching of the Cr(III) occurs strictly under acidic conditions, whereby limning of these sediments will give rise to the lower solubility of Cr(III). The key mineral phases responsible for the fast release of the Cr(VI) are: the chromate salts (i.e. sodium chromate and sodium dichromate), while sparingly soluble chromatite (CaCrO₄) and hashemite (BaCrO₄) release Cr(VI) very slowly. Thus, pH and mineral solubility have been identified as key factors in the retention and the release of the hexavalent CrO₄ ²⁻ and Cr₂O₇ ⁻ from the COPR-rich pond sediments.     

稀土元素地球化学在锡矿床成因及找矿研究中的应用

研究锡矿床中花岗岩、赋矿地层、蚀变岩石和锡石的稀土地球化学特征,来探讨各类锡矿床成因.并总结了花岗岩成矿性评价的稀土地球化学定量标志.     

钇易解石族的端员—钛钇易解石的发现

本矿物为新发现的钇易解石族的端员矿物－钛钇易解石，产于江西省龙南县足洞燕山期中粒白云母花岗岩及其风化壳中。矿物属斜方晶系，常呈板状或短柱状，为天然晶质体，浅黄色，粒度为０．０７５ｍｍ，硬度４．７，比重４．７３，二轴正晶，Ｎｇ＝２．２４８，Ｎｍ＝２．２１２，Ｎｐ＝２．１９４，Ｎｇ－Ｎｐ＝０．０５４，２Ｖ＝７０°。空间群为Ｄ＾１６２ｈ－Ｐｍｎｂ，ａ０＝０．７５０ｎｍ，ｂ０＝１．０９２ｎｍ，Ｃ０＝０．５     

莫托萨拉一带稀土元素地球化学特征及其地质意义

对莫托萨拉一带不同时代地质体中不同岩石稀土元素的分布,配分,比值进行研究,并探讨它们之间的某些成因关系,从分析结果看,莫托萨拉石炭系和三叠系花岗质砾岩,砂岩系盆地周围花岗质岩浆岩的风化产物,铁锰矿与火山岩间在稀土元素方面关系不密切,奥热且克沟铜矿石与变质围岩间有较密切的关系。     

松潘—甘孜造山带中巴西金-矽卡岩矿床成矿热液系统演化的(REE、Sr、O)证据

本文通过对巴西典型金-矽卡岩矿床的解剖，探讨了成矿流体来源、组成演化，以及流体和岩石之间的质量转移程度和机理的信息，揭示金成矿过程中成矿流体演化的规律。研究认为，成矿作用两阶段的成矿流体分别为变质流体和大气降水，它们在开放系统中水岩质量比分别为0．02，2．11，并且获得矽卡岩可能是由围岩转向岩体方向的变质流体交代形成的认识。     

REE-HFSE distribution/partitioning between garnetiferous restites and TTG from Nademavinapura area,Western Dharwar craton

The major part of the Peninsular Gneiss in Dharwar craton is made up of Trondjhemite-Tonalite-Granodiorite (TTG) emplaced at different periods ranging from 3.60 to 2.50 Ga. The sodic-silicic magma precursors of these rocks have geochemical features characteristic of partial melting of hydrated basalt. In these TTGs, enclaves of amphibolites (± garnet) are abundant. These restites are considered to be the residue of a basaltic crust after its partial melting. A detailed study of these (residue) enclaves reveals textures formed due to the process of partial melting. Major, trace and REE analysis of these residue enclaves and the melt TTGs and microprobe analysis of the coexisting minerals show partitioning of REE and HFSE between the precursor melt of TTGs and the upper amphibolite facies residues. Formation of garnetiferous amphibolites with biotite, Cpx and plagioclase consequent to melting, has squeezed the original MORB type of basaltic crust and given rise to the TTGs, depleted in Y, Yb, K₂O, MgO, FeO, TiO₂ and enriched in La, Th, U, Zr and Hf. Coevally during the process of melting, the hydrated basalt was depleted in Na₂O, Al₂O₃, LREE, Th, U and enriched in K₂O, MgO, Nb, Ti, Yb, Y, Sc, Ni, Cr and Co. Mineral chemistry of co-existing garnet-biotite and amphibole-plagioclase in these amphibolitic (restite) enclaves indicates an average temperature of 700 ± 50° C and pressure of 5 ± 1 Kbar. These data are inferred to indicate that during the garnet stability field metamorphism, effective fractionation of HREE and HFSE has taken place between the restites having Fe-Mg silicates, ilmenites and the extracted melt generated from the MORB type of hydrated basalt. These results are strongly substantiated by the reported melting experiments on hydrated basalts.     

Rare earth elements in waters from the albitite-bearing granodiorites of Central Sardinia, Italy

With the aim of contributing to the knowledge of the geochemical behaviour and mobility of the rare earth element (REE) in the natural water systems, the ground and surface waters of the Ottana-Orani area (Central Sardinia, Italy) were sampled. The study area consists of albititic bodies included in Hercynian granodiorites. The waters have pH in the range of 6.0-8.6, total dissolved solid (TDS) of between 0.1 and 0.6 g/l, and major cation composition dominated by Ca and Na, whereas predominant anions are Cl and/or HCO₃.The pH and the major-element composition of the waters are the factors affecting the concentration of REE in solution. The concentrations of ∑REE+Y in the samples filtered at 0.4 μm vary between 140 and 1600 ng/l, with La of between 14 and 314 ng/l, and Yb of between <6 and 12 ng/l. A negative Ce anomaly, especially marked at high pH, is observed in the groundwaters. The surface waters show lower REE concentrations, which are independent of pH, and negligible Ce anomaly.Speciation calculations, carried out with the EQ3NR computer program, showed that the complexes with the CO₃²⁻ ligand are the dominant REE species at pH in the range of 6.7-8.6. The REE³⁺ ions dominate the speciation at pH <6.7 and only in the light REE (LREE).The relative concentrations of REE in water roughly reflect those in the aquifer host rocks. However, when concentrations of REE in water are normalised relative to the parent rocks, a preferential fractionation of heavy REE (HREE) into the water phase can be observed, suggesting the greater mobility and stability of HREE in aqueous solution.     

金山韧性剪切带大型金矿床稀土元素地球化学

根据ＲＥＥ含量及其组成和∑ＲＥＥ、∑Ｃｅ／∑ｙ、δＥｕ、（Ｌａ／Ｙｂ）Ｎ……参征参数，以金山金矿床为例，探讨“金山式”矿床的形成、演倾与成矿的ＲＥＥ地球化学特征。     

Geochemistry of the Rare Earth Elements in Natural Terrestrial Waters：A Review of What Is Currently Knows

The range of observed chemical compositions of natural terrestrial waters varies greatly especially when compared to the essentially constant global composition of the oceans.The concentrations of the REEs in natural terrestrial waters also exhibit more variation than what was reported in seawater,In terrestrial waters ,pH values span the range from acid up to alkaline,In addition,terrestrial waters can range from very dilute waters through to highly concentrated brines.The REE concentrations and their behavior in natural terrestrial waters reflect these compositional ranges,Chemical weathering of rocks represents the source of the REEs to natural terrestrial waters and ,consequently,the REE signature of rocks can impart their REE signature to associated waters,In addition,Because of the typical low solubilities of the REEs both surface and solution complexation can be important in fractionating REEs in aqueous solution.Both of these processes are important in all natural terrestrial waters,however,their relative importance varies as a function of the overall solution composition,In alkaline waters,for example,Solution complexation of the REEs with carbonate ions appears to control their aqueous distributions whereas in acid waters,the REE signature of the labile fraction of the REEs is readily leached from the rocks.In circumneutral pH waters,both processes appear to be important and their relative significance has not yet been determined.