江西足洞和关西花岗岩的稀土元素地球化学及矿化特征

足洞和关西岩体分别为花岗岩风化壳离子吸附型重、轻稀土矿床的原岩。足洞岩体的∑REE¹⁾为264ppm,LREE/HREE²⁾值为0.81-024,平均的钇对∑REE占有率为35.8-54.5%。这主要是由于岩浆结晶演化及晚期有交代钠长石化、白云母化和萤石-氟碳钙钇矿化的结果。这些蚀变产生了钇族稀土氟碳酸盐、硅酸盐和砷酸盐等内生矿化作用。     

The Carboniferous at the Northern Foot of the Dabie Mountains and Its Tectonic Implications

In the Qinling orogenic belt. oceanic crust originated in the Early Palaeozoic. while the product of conti-nental collision appeared as late as after the Triassic. The Late Palaeozoic records there are of major impor-tance for understanding the tectonic regime at that time. The Carboniferous and even Permian sequences andthe distribution of sedimentary facies in northern Huaiyang indicate that the rocks were formed in a large basinopening towards the south. Regional stratigraphic correlation shows that the interior of the Qinling orogenicbelt was a sea trough lying between the Yangtze and North China plates in the middle part of the LatePalaeozoic. With subsequent northward migration of the South China Sea, the two seas were connected witheach other. Both the melanges and the Dabie block ia the eastern sector of the Qinling belt were formed in theMesozoic ?.     

Post-orogenic and anorogenic A-type fluorite-bearing granitoids, Eastern Desert, Egypt: Petrogenetic and geotectonic implications

The present study focuses on four A-type fluorite-bearing granitic plutons in the Eastern Desert of Egypt which are classified into post-orogenic subsolvus (Homrit Waggat, 535 Ma; Homer Akarem, 541 Ma and Ineigi, 571 Ma) and anorogenic hypersolvus (Gabal Gharib, 476 Ma) granites. All the granites are Si- and alkali-rich and MgCaTi poor. Whereas both granite types appear relatively homogeneous in terms of most of their major and trace elements, they differ in that the subsolvus granites are depleted in TiO₂, FeO^*, Ba, Sr and Zr and enriched in Rb and Y with respect to the hypersolvus granites. The two granite types, however, can be distinguished more easily by their rare-earth element (REE) patterns. Chondrite-normalized REE patterns of the hypersolvus granite display a gull-wing shape, characterized by a large negative Eu anomaly and moderate-to-high LREE contents. Relative to the hypersolvus granite, subsolvus granite is depleted in LREE and more enriched in HREE contents. The increase of HREE in the subsolvus granite is presumably caused by F complexing during the late stage of its evolution. This is supported by the abundance of fluorite veins cross-cutting the subsolvus granite. The negative Eu anomalies in the subsolvus granite point to the role of feldspars as residual phase in the source, and as a crystallizing phase during magmatic differentiation.Field relations, textural, mineralogical and geochemical data of the post-orogenic subsolvus granite are consistent with its derivation from a parental basic magma through crystal-liquid fractionation of alkali feldspar, plagioclase, amphibole, FeTi oxides, titanite, zircon, monazite and allanite. Crystallization occurred in a water-enriched and rather oxidizing environment, as a result of which the entire suite has a transitional character between that of a post-orogenic and an anorogenic setting. On the other hand, the most credible mechanism for the origin of the anorogenic hypersolvus granite is partial melting of I-type granodiorite-monzogranite source rocks in the study area.     

Petrological and geochemical characteristics of Zhaibei granites in Nanling region,Southeast China: Implications for REE mineralization

Mineralization with ion adsorption rare earth elements (REEs) in the weathering profile of granitoid rocks from Nanling region of Southeast China is an important REE resource, especially for heavy REE (HREE) and Y. However, the Jurassic granites in Zhaibei which host the ion adsorption light REE (LREE) ores are rare. It is of peraluminous and high K calc-alkaline composition, which has similar geochemical features of high K₂O + Na₂O and Zr + Nb + Ce + Y contents and Ga/Al ratio to A-type granite. Based on the chemical discrimination criteria of Eby [Geology 20 (1992) 641], the Zhaibei granite belongs to A1-type and has similar source to ocean island basalts. The rock is enriched in LREE and contains abundant REE minerals including LREE-phosphates and halides. Minor LREE was also determined in the feldspar and biotite, which shows negligible and negative Eu anomalies, respectively. This indicates that the Zhaibei granite was generated by extreme differentiation of basaltic parent magmas. In contrast, granites associated with ion adsorption HREE ores contain amounts of HREE minerals, and show similar geochemical characteristics with fractionated felsic granites. Note that most Jurassic granitoids in the Nanling region contain no REE minerals and cannot produce REE mineralization. They belong to unfractionated M-, I- and S-type granites. Therefore, accumulation of REE in the weathering profile is controlled by primary REE mineral compositions in the granitoids. Intense fractional crystallization plays a role on REE enrichment in the Nanling granitoid rocks.     

Tveitite-(Y) and REE-enriched fluorite from amazonite pegmatites of the Western Keivy,Kola Peninsula,Russia: Genetic crystal chemistry of natural Ca,REE-fluorides

Tveitite-(Y) as pods up to 10 cm across has been found at Mt. Rovgora, the Western Keivy, Kola Peninsula, Russia, in an albite-quartz-amazonite pegmatite vein related to alkaline granite. Tveitite-(Y) grains (up to 4 cm) are parallel microintergrowths of two isostructural varieties, Ca_9.5Na_1.7Y_5.2Ln_2.0F_42.6 and Ca_11.4Na_1.9Y_4.4Ln_1.4F_42.0. The idealized structural formula (Z = 3) is (Y, Na)₆(Ca, LREE)₆(Ca, Na, HREE)₆(Ca, Na)F₄₂; the simplified formula is (Ca, REE, Na)₁₃(Y, Na)₆F₄₂; space group R \(\bar 3\) a = 17.020, c = 9.679 Å. [Lanthanoides are abbreviated in this paper as Ln, whereas Ln + Y as REE]. Nine fluorite samples containing from 0 to 18 mol % (REE)F₃ were examined by electron microprobe, X-ray powder diffraction, and IR spectroscopy. The crystal structure of natural yttrofluorite has been determined for the first time (R _aniso = 1.47 %): Fm3m, a = 5.493 Å; the structural formula is (Ca_0.82Y_0.12Ln_0.06)F_2.15. Earlier published and new data show that yttrofluorite containing (REE)F₃ > 20 mol % and REE-enriched fluorite with LREE > Y (HREE) are metastable under room conditions. In nature, tveitite-(Y) is a product of solid-state transformation of metastable yttrofluorite with (REE)F₃ > 20 mol %. Inferred protophases could have been exsolved into tveitite-(Y) variable in composition or tveitite-(Y) + yttrofluorite stable under normal conditions. The formation of tveitite-(Y) requires the erichment of a protophase not only in Y but also in LREE and HREE as stabilizing admixtures regularly distributed by different types of Ca-dominant structural sites. Tveitite-(Y) and yttrofluorite are geochemical indicators of a medium that is not only enriched in Y, Ln, and F, but also depleted in Na, Ca, CO₂ and P.     

Determination of the Neoproterozoic Shicaogou Syn-collisional Granite in the Eastern Qinling Mountains and Its Geological Implications

The Shicaogou granite has been identified as a magnesian (Fe-number=0.71-0.76), calcic to calc-alkalic (MALI=3.84-5.76) and peraluminous (ASI=1.06-1.13) granite of the syn-collisional S-type, with high SiO2(>71%), A12O3 (>13%) and Na2O+K2O (6.28%-7.33%, equal for NaO2 and K2O). Trace element and REE analyses show that the granite is rich in LILE such as of Rb, Sr, Ba and Th, and poor in HFSE like Yb, Y, Zr and Hf. Its Rb/Sr ratio is greater than 1; the contents of Nb and Ta, and the ratio of Nb/Ta as well as the REE geochemical features (e.g. REE abundance, visible fractionation of LREE and HREE and medium to pronounced negative Eu anomalies) are all similar to those of crust-origin, continent-continent syn-collisional granite. Moreover, the granite exhibits almost the same pattern as that of the typical continent-continent syn-collisional granite on the spider diagram and all samples fall within the syn-collisional granite field.The cathodoluminescence (CL) investigations have revealed that the zircon f     

内蒙古林西萤石矿床稀土元素地球化学特征及其指示意义

内蒙古林西县萤石矿产资源丰富,已知萤石矿床（点）68处。萤石矿床产出于中生界火山-沉积岩地层中,矿体主要受近 SN 向或 NNE 向断裂破碎带控制。为了研究水头地区萤石矿床的成矿流体来源和成矿机理,文章对矿床稀土元素进行了分析。结果表明萤石和方解石的稀土元素总量（∑REE）为4.37-159μg/g, LREE/HREE比值为0.24-1.80,δEu =0.57-1.60,具弱Ce负异常（0.81-0.98）特征, Y/Ho比值为21-78,平均41。从成矿早阶段到晚阶段,∑REE值及LREE/HREE比值均逐渐减小,晚阶段萤石具有重新活化、重结晶的特征。结合赋矿地层及矿区外围花岗岩体REE特征分析,认为其成矿流体迁移距离较远,稀土元素和成矿元素可能来自下伏高F地体和含Ca赋矿火山-沉积地层,为热液成因-破碎带充填交代型萤石矿床。     

“寨背式”离子吸附型稀土矿床多类型稀土矿化及其成因

赣南寨背离子吸附型稀土矿床产于寨背复式花岗岩体的风化壳中,自20世纪80年代发现以来一直以轻稀土型开采,近年在轻稀土型花岗岩风化壳中发现了重稀土矿。为了探讨轻稀土型花岗岩风化过程中重稀土元素的迁移、分馏和富集机制,本文选择了区内三个具有代表性的风化壳钻孔(ZK1、ZK2和ZK4)对其进行了全相和离子交换相稀土元素地球化学研究。结果显示：钻孔ZK4中离子交换相稀土含量介于14.90×10^-6～835.8×10^-6之间,并富集轻稀土(LREE/HREE=2.28～10.78);钻孔ZK1中离子交换相稀土含量达1470×10^-6(9件样品均值),具有从轻稀土型向重稀土型过渡的配分特征(LREE/HREE=1.30～1.65),并且剖面自上而下显示轻、重稀土逐渐富集的趋势;钻孔ZK2中离子交换相稀土含量为492.4×10^-6(8件样品均值),自上而下稀土配分类型从轻稀土型过渡至重稀土型(LREE/HREE=0.43～2.25),且轻稀土富集在全风化层上部而重稀土则富集在下部。三个钻孔的Nb/Ta和Zr/Hf...     

内蒙古宝日拉锦乌拉钠闪石花岗岩特征

宝日拉锦乌拉钠闪石花岗岩岩体位于大兴安岭中段东坡,形成于早白垩世晚期或更晚些.钠闪石花岗岩富SiO₂（含量为71.63%~77.35%）,富碱（ALK=4.94%~9.17%）,贫铝、镁、钙.钠闪石花岗岩的稀土元素总量极高,其中钠闪石钾长花岗岩的稀土总量在271.77×10^-6~701.77×10^-6之间,而钠闪石二长花岗岩中的稀土元素总量在2938×10^-6~6933.2×10^-6之间.轻、重稀土元素比值在1.63~7.49之间,大部分在2~5之间,稀土配分曲线为略呈右倾的“V”字形,说明轻、重稀土元素的分馏程度较差.δEu值极低,在0.016~0.035之间,说明该岩石的Eu负异常极为明显.研究区出露的钠闪石花岗岩形成于板块内部非造山的相对稳定的构造环境.     

南岭地区钨锡铌钽花岗岩及其成矿作用

在晚侏罗世时,南岭地区发生了与花岗岩有关的钨锡铌钽大规模成矿作用。依据花岗岩的岩石学、地球化学及其矿化特征,可将南岭地区含钨锡铌钽花岗岩划分为三个主要类型：含钨花岗岩、含锡钨花岗岩和含钽铌花岗岩。含钨花岗岩的地球化学特征可归纳为铝过饱和,低Ba+Sr 和TiO2,轻重稀土比值低,铕亏损强烈,富Y 和Rb,Rb/Sr 比值高,分异强烈。含锡钨花岗岩总体特征表现为TiO2 含量高,准铝质—弱过铝质,轻重稀土比值和CaO/(K2O+Na2O)比值高,富高场强元素、稀土、Ba+Sr 和Rb,低Rb/Sr 比值,分异演化程度较低。含钽铌花岗岩的地球化学特征主要为TiO2 含量和CaO/(K2O+Na2O)比值低,Al2O3/TiO2 和Rb/Sr 比值明显偏高,强过铝质,贫Ba+Sr、稀土和高场强元素,铕亏损强烈,明显富Rb 和Nb,高度分异演化。三类含矿花岗岩具有明显不同的演化特征,成矿作用与它们的演化密切相关。黑云母花岗岩主要与锡成矿作用有关,二云母花岗岩和白云母花岗岩主要产生钨矿化或锡钨共生矿化,钠长石花岗岩主要与钽铌或锡（钨）钽铌矿化有关。总结了南岭锡钨钽铌矿床的重要类型,提出了绿泥石化花岗岩型锡矿新类型,指出南岭地区要特别注意在含锡钨花岗岩中寻找此类锡矿和云英岩- 石英脉型锡钨矿。     

Magmatic and hydrothermal R.E.E. fractionation in the Xihuashan granites (SE China)

The Xihuashan stock (South Jiangxi, China) is composed of cogenetic granitic units (granites Xe, a, c, d and b) and emplaced during the Yanshanian orogeny (153±0.2 Ma). They are two feldspars, Fe-rich biotite±garnet and slightly peraluminous granites. Primary accessory minerals are apatite 1, monazite, zircon, uranothorite±xenotime in granites Xe and a, zircon, uranothorite, uraninite, betafite, xenotime 1; hydrothermal minerals are monazite altered into parisite and apatite 2, Y-rich parisite, yttroparisite, Y-rich fluorite and xenotime 2 in granites c and b. Petrographic observations, major element, REE, Y and Rb–Sr isotropic data point to a magmatic suite (granites Xe and a granites c and d granite b) distinct from hydrothermal Na-or K-alteration of b. From granite Xe to granite b, LREE, Eu, Th and Zr content are strongly depleted, while HREE, Y and U content increase. During K-alteration of b, these variations are of minor importance. Major and accessory mineral evidences, geochemical and fluid inclusion results indicate two successive alteration fluids interacting with b, (1) a late-magmatic F^– and CO₂–rich fluid and (2) a post-magmatic, aqueous and slightly saline fluid. The depletion of LREE and Th content and the increase in HREE, Y and U content correspond, in the magmatic suite to the early fractionation of monazite in the granites where there is no hydrothermal alteration (granites Xe and e) and to the hydrothermal alteration of monazite into parisite and secondary apatite, intense new formation of yttroparisite, Y enrichment and U loss in the uranothorite and late crystallization of uraninite in the granites c and b. Moreover, simulated crystallization of monazite and temperature of monazite saturation show early fractionation of monazite from the magma in the less evolved granites (Xe and e) and prevailing hydrothermal leaching of monazite in the most evolved granites (c-d and b) related to a late-magmetic event. The slight variations of REE, Y, Th and U content in the K-altered granites compared to granite b emphazes the distinct chemical nature of the successive hydrothermal fluids. Rb–Sr and Sm–Nd isotopic results point to a 30 Ma period of time between the late-magmatic and the post-magmatic fluid circulation.     

Petrogenetic significance of rare-earth element behavior in the basement rocks of southern Obudu Plateau, Bamenda Massif, southeastern Nigeria

Rock samples representing various igneous and metamorphic rocks of southern Obudu Plateau were analyzed for rare-earth element ( REE ) behavior by ICP-MS. Results of the analyses indicate a range of REE abundances and distinctive patterns from highly fraetionated patterns with negative Eu anomalies in granitic rocks to relatively low abundances and less REE fractionated flat patterns with little Eu anomaly in some paragneisses, schists, enderbites and dolerites to unfractionated patterns with positive Eu anomalies in some paragneisses and charnockites. Over all, there are low to high ∑ REE contents with negative to positive Eu anomalies. The ratios of different parameters, especially La/Yb and Ce/Yb, show behaviors consistent with crustal to mantle derivation. The heterogeneity of REE abundances and REE patterns reflects mantle to crustal petrogenetic variations of different rock suites on the Plateau. The LREE content is higher than the HREE content in the highly differentiated rocks, as evidenced by their La/Yb,Ce/Yb and La/Sm ratios, which are normally higher in residual products than in primary melts. The dominantly intermediate nature of the source rock of the orthogneisses is suggested by the generally low ∑ REE. The granites enriched in LREE and depleted in HREE and some of the charnockites with negative Eu anomalies were probably formed by partial melting and crystallization.     

Geology, geochemistry and petrogenesis of intrusive rocks of the Wallagga area, western Ethiopia

Crystalline rocks from the western Ethiopian Precambrian terrain comprise two major rock groups: (1) the often migmatised eastern and western high-grade gneisses; and (2) the central low-grade metavolcanosedimentary rocks. Granitoid bodies of different ages and compositions intrude these rocks. Field observations, petrographic investigations, and geochemical features support a two-fold classification of the granitoid rocks. The volcanic arc granitoids (VAG) are most common and include the Ujjukka granite and granodiorite, and the Dhagaa Booqa and Guttin K-feldspar megacrystic granites. The second and geographically more restricted group represents within-plate or anorogenic (A-type) granitoids, typified by the Tullu Kapii syenite. Geochemically, the Tullu Kapii syenite is characterised by moderate to high contents of SiO₂, total alkalis, Y, Nb, Ta, Hf, Zn, Zr, Ga, ΣREE, higher ratios of Fe₂O_3(total)/MgO, , , and lower contents of CaO, MgO, Sr, and Ba, compared to the other granitoids. The VAG group shows chondrite-normalised REE patterns with slightly enriched LREE and flat HREE patterns without significant Eu anomalies. In contrast, the Tullu Kapii A-type granitoid is characterised by a nearly horizontal REE pattern with variable negative Eu anomalies. The Ujjukka granite and granodiorite; and the Dhagaa Booqa and Guttin K-feldspar megacrystic granites originated in a two-step process, which involves batch equilibrium melting of basaltic or andesitic material producing tonalitic magma, followed by fractional crystallisation. The Tullu Kapii syenite was the product of partial melting of source rocks enriched in high field strength elements.     

Regional Tectonic Transformation in East Kunlun Orogenic Belt in Early Paleozoic: Constraints from the Geochronology and Geochemistry of Helegangnaren Alkali-feldspar Granite

The Helegangnaren feldspar granite exposed in the eastern part of East Kunlun, is characterized by high concentrations of SiO2 and alkaline, low abundances of Fe, Mg and Ca, metaluminous-weak peraluminous. Trace elements analysis shows that the granite is depleted extremely in Ba, Sr and Eu, and rich in some large-ion lithophile elements and high field strength elements. Besides, the granite has high Ga contents, the values of 104(Ga/Al) vary from 2.50 to 2.77, which is mainly greater than the lower limit of A-type granites (2.6), and is higher than the I- and S-type granites’ average (2.1 and 2.28, respectively). Rare earth element (REE) is characterized by relatively high fractionations of light REE (LREE) and heavy REE (HREE) (LREE/HREE=9.3–13.60, (La/Yb)N=10.92–18.02), pronounced negative Eu anomalies (δEu=0.08–0.13), and exhibits right-dipping gull pattern. Major elements, rare elements and trace elements features show the granite is ascribed to A-type granite and A2 subtype in tectonic genetic type. They are plotted into post-collision or within-plate area in a variety of tectonic discriminations. Geological and geochemical data comprehensively suggest that the granite is formed in a post-collision extensive tectonic setting. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U-Pb dating yields a weighted mean age of 425?Ma, belonging to Middle Silurian, which is similar to the age of the post-collision geological events in the region. The differences of magmatic rocks in formation age, rocks assemblage and rocks series systematically indicate that the regional tectonic stress regime in the East Kunlun orogenic belt experienced a major transformation from compress to extension in Middle Silurianin, and the Helegangnaren feldspar granite intruded in the early stage of tectonic transformation.     

Zonal REE + Y profiles in garnet and their genetic implications: A case study of metapelites from the northern Ladoga region

The objective of this study is to provide insights into the REE and Y behavior during garnet porphyroblast formation in staurolite-bearing schists as a constituent of Late Paleoproterozoic metapelites of the Ladoga Complex. The MnNCKFMASH P–T pseudosection for a single sample and Grt–Bt thermometry indicate that the garnet core grew at 520°C and under 7.0–7.2 kbar in the Grt–Bt–Pl–Chl–Ms–Zo field, whereas the garnet rim was equilibrated at 590–600°C and under 3.5–4.0 kbar. The measured zoning profiles are strongly depleted in REE + Y in the garnet core containing high Mn and Ca concentrations. The intermediate zone of garnet is enriched in La, Ce, Pr, and Nd (inner LREE + Nd annulus), as well as in Dy, Er, Yb, Lu, and Y (outer HREE + Y + Dy annulus). According to pseudosection analysis, these peaks were probably produced owing to breakdown of epidote-group minerals (allanite, REE-rich epidote) at T < 535°C and P > 6.5 kbar. Towards the rim, the HREE + Y contents gradually decrease, whereas MREE (Sm, Eu, Gd) display an inverse trend. The rim also exhibits a negative Eu anomaly. The former tendency reflects an increase in temperature during garnet crystallization and partitioning of elements between garnet and monazite. It is thought that the latter is linked to oppositely directed change in garnet-monazite partition coefficients for HREE and MREE with increasing temperature.     

Are South China granites special in forming ion-adsorption REE deposits?

Ion-adsorption REE deposits associated with clay minerals are the main global HREE producer. The majority of these deposits are formed by the weathering of granites in South China, but whether there is any fundamental difference between the granites in and outside South China is still unclear. Besides, an effective evaluation system of granite mineralization potential is urgently needed for HREE exploration.To answer this question, we compiled a global granite geochemical dataset from within (n = 1932) and outside (n = 6109) South China, together with a dataset of representative REE deposits in South China (n = 128). The geochemical comparation shows that the South China granites share similar REE contents with those of many granites from places outside South China. Such similarity has also been found between REE ore-related and ore-barren granites in South China. This shows that granites from outside South China could also have ore-forming potential. Warm humid climate and quasi-equalized crustal state promote chemical weathering to continuously leach REEs and store them in the weathering crust. The enrichment ratio (Rx) can be used to quantify the climatic effect between orebodies and parent rocks. The calculated average Enrichment Ratios (Rx) of LREE- and HREE-rich deposits are 2.41 and 2.68, respectively. Sufficient REE content in granite is the prerequisite for mineralization, and we propose that the combination of the minimum REE + Y (172 and 108 ppm in LREE- and HREE-rich parent rocks, respectively) and REE oxide ratio (1.32) can reveal the granite metallogenic potential. Together with the suitable tropical and temperate climate area with ion-adsorption REE deposits, we further identified certain regions with high REE mineralization potential outside South China to assist future exploration.     

西藏日土县拉热拉新花岗岩体特征及构造环境

拉热拉新花岗岩体属于唐古拉-东达山花岗岩带西段羌塘花岗岩区的组成部分,岩石类型主要为黑云角闪闪长岩、黑云角闪石英闪长岩、黑云角闪石英二长岩、黑云花岗闪长岩、黑云二长花岗岩、黑云花岗岩。其地球化学特征表现为：富Si,K,贫Ti,Mg,Fe,Ca,铝饱和指数ACNK〈1．1,稀土元素球粒陨石标准化图式呈右倾斜的“V”字型,LREE富集,HREE相对亏损,铕亏损。其形成时代为早白垩世,为多期次同碰撞的同熔型花岗岩。     

云南省澜沧县离子吸附型稀土矿床地质特征分析与成矿过程探讨

云南省澜沧县地处临沧花岗岩的中南段，在其境内发现多地与花岗岩风化壳有关的离子吸附型稀土矿床。文章通过对该区晚三叠世黑云母二长花岗岩风化壳全风化层的剖面及钻孔样品分析，对赋存于花岗岩风化壳离子吸附型稀土矿床的成矿地质地球化学特征进行研究，探讨其关键成矿过程并总结地形地貌与风化壳和矿体露头的关系。研究表明，黑云母二长花岗岩风化壳分层特征明显，离子吸附型稀土矿体规模及形态严格受风化壳发育程度及微地貌控制；花岗岩风化壳全风化层稀土元素配分曲线呈右倾平滑的浅“W”型，轻稀土元素的分异程度强于重稀土元素；除Ce元素外，轻稀土元素的浸出率略高于重稀土元素；矿石类型为以轻稀土元素为主、中重稀土元素配分齐全的混合型稀土矿。通过厘定离子吸附型稀土矿床的关键成矿过程，文章发现内应力、渗透能力、风化程度、黏土矿物含量在风化壳剖面中由上至下变化特征综合决定了稀土矿体主要定位于风化壳全风化层。     

Rare Earth Element and Trace Element Features of Gold-bearing Pyrite in the Jinshan Gold Deposit, Jiangxi Province

<正>Jinshan gold deposit is located in northeastern Jiangxi,South China,which is related to the ductile shear zone.It has a gold reserve of more than 200 tons,with 80%of gold occurring in pyrite. The LREE of gold-bearing pyrite is as higher as 171.664 ppm on average,with relatively higher light rare earth elements(LREE;159.556 ppm) and lower HREE(12.108 ppm).TheΣLREE/ΣHREE ratio is 12.612 and(La/Yb)_N is 11.765.These indicate that pyrite is rich in LREE.The(La/Sm)_N ratio is 3.758 and that of(Gd/Yb)_N is 1.695.These are obvious LREE fractionations.The rare earth element(REE) distribution patterns show obvious Eu anomaly with averageδEu values of 0.664,andδCe anomalies of 1.044.REE characteristics are similar to those of wall rocks(regional metamorphic rocks),but different from those of the Dexing granodiorite porphyry and Damaoshan biotite granite.These features indicate that the ore-forming materials in the Jinshan gold deposit derived from the wall rocks, and the ore-forming fluids derived from metamorphic water.The Co/Ni ratio(average value 0.38) of pyrite suggests that the Jinshan gold deposit formed under a medium-low temperature.It is inferred from the values of high-field strength elements,LREE,Hf/Sm,Nb/La,and Th/La of the pyrite that the ore-forming fluids of the Jinshan gold deposit derived from metamorphic water with ClF.     

Trace and rare earth elements in cassiterite — sources of components for the tin deposits of the Mole Granite,Australia

Trace and rare earth elements have been determined for cassiterite from deposits associated with the Mole Granite and hosted by granite, metasediments and metavolcanics. The REE of cassiterite is controlled by the REE of the the ore fluid and the rocks through which this fluid circulated. The REE distribution factor and LREE/HREE value of cassiterite is strongly influenced by the associated mineral assemblage, the fluid chemistry and the crystal chemical characteristics of the host mineral. Cassiterite from deposits hosted by granite have trace and rare earth element characteristics similar to those determined for the Mole Granite. Cassiterite from deposits hosted by metasediments or acid volcanics have most trace and rare earth element characteristics similar to those of the enclosing rocks and some characteristics similar to the Mole Granite. The ore fluid had chemical components derived from the parental granite and components acquired by passage through the metamorphosed aureole.