长江中下游地区若干Cu（Au）,Cu—Fe（Au）和Fe矿床中钙质夕卡岩的稀土元 …

本区夕卡岩的稀土元素（ＲＥＥ）分布模式表现为富集轻稀土元素（ＬＲＥＥ）的直线型和以Ｃｅ、Ｐｒ或Ｎｄ为峰值的折线型。夕卡岩全岩中的ＲＥＥ分布模式基本上受石了石中的ＲＥＥ的分配行为控制。石榴子石富信ＬＲＥＥ可能是承袭形成它们的初始物中ＲＥＥ丰度和分配行为的反映。石榴子天生中ＲＥＥ分布的不均匀性、石榴子石微裂隙及包裹体中ＲＥＥ的丰度可能是导致直线型和过渡型ＲＥＥ分布模式的主要原因。石榴石石中折线型ＲＥＥ     

大冶-武山矿化夕卡岩的稀土元素地球化学研究

用ICP-MS分析了25个含矿夕卡岩样品的REE含量,其中对8个样品的石榴子石等矿物中的熔融包裹体进行了均一温度测定,还对5个夕卡岩样品石榴子石中的熔融包裹体进行了电子探针分析.在这些样品的石榴子石、辉石或方解石中都观察到熔融包裹体.夕卡岩的球粒陨石标准化REE分布模式具有两个突出特点:其一是以富集轻稀土元素(LREE)右倾为特征;其二是多数以具有Eu正异常为特征.夕卡岩球粒陨石标准化REE分布模式有三种类型:第一类型显示斜率不大的右倾直线;第二类型具有以Ce为峰值的折线的特征,即REE线段向上凸,在Ce处有一极大值(个别无峰值,LREE曲线向上凸,呈穹隆状);第三类型为过渡型REE分布模式.在当今REE资料有限的情况下,利用稀土元素地球化学特点鉴别夕卡岩成因是困难的.     

浪都夕卡岩型铜矿床中石榴子石稀土元素地球化学研究

文中对浪都矿床夕卡岩中石榴子石进行了主量和稀土元素研究。分析结果表明研究区石榴子石为钙铁榴石-钙铝榴石固溶体系列,成分变化于Ad_(87)Gr_(13)-Ad_(92)Gr_8之间,以钙铁榴石为主。与世界上很多夕卡岩矿床中石榴子石REE配分模式截然不同,研究区石榴子石稀土元素总量较低、配分模式表现为轻稀土富集,重稀土亏损,并且具有明显的Eu正异常。研究显示,浪都矿床钙铁榴石是在水/岩比值较高的环境下快速形成,其与流体之间并没有完全达到REE平衡。岩浆热液中REE的配分模式、表面吸附可能为制约石榴子石REE含量及配分模式的主要因素。Eu~(2+)(r=1.25 A)与其他REE~(3+)相比具有更大的离子半径,更容易被吸附在石榴子石晶体表面,可能是形成浪都矿床中石榴子石Eu正异常的主要原因。     

层控夕卡岩及有关矿床形成过程的稀土元素行为——以安徽冬瓜山矿床为例

对安徽省冬瓜山层控夕卡岩型铜（金）矿床中穿层方向上不同蚀变程度的大理岩，顺层方向上距岩体远近不同但垂向深度的块状石榴子石夕卡岩及其主矿物石榴子石，不同演化阶段的石英及矿石等到的REE特征进行了系统研究，结果显示，在穿层方向上，大理岩被交代的程度愈深其稀土总量（∑REE）愈高，Eu负异常愈显著，尽管，夕卡岩全岩的RE分布模式与原岩（大理岩）相似，但前者的稀土总量（∑REE）远高于后者，且Eu异常更为显著，显然不是继续承原岩的REE特征所致，而是受控于其主矿物石榴子石的REE特征，后者又由参与交代作用的岩浆热液REE所决定，热液中的REE具有缓和右倾型分布模式，LREE富集，较显著的Eu负异常等基本特征，石榴子石晶体基本承袭了热液的REE特征，REE的空间变化特征结果地层的构造特征可以揭示夕卡岩及相关矿体形成过程中流体的输运径及输运方式，REE的研究有助于深化对层控夕卡岩及其相关矿床形成过程的认识。     

热水沉积电气石岩稀土元素地球化学特征

阐述了辽东元古宙大陆型裂谷内层状硫化物矿床中伴生的电气岩稀土元素特征。含矿建造内的电气石岩具有ＲＥＥ总量低，较强的Ｅｕ正异常和Ｃｅ负异常，稀土元素属（ＬＲＥＥ／ＨＲＥＥ）Ｎ＞１．３的富集型，为热水沉积的产物。纹层状电气石岩的ＲＥＥ研究证明，成矿流体来自富含挥发份的深源。     

接触交代夕卡岩型矿床中石榴子石和辉石成分特点及其与矿化的关系

本文对中国十四个接触交代钙夕卡岩矿床和钙-镁夕卡岩矿床中的三百多个样品的石榴子石和辉石成分进行了电子探针分析。不同矿床类型的石榴子石和辉石成分代表着钙夕卡岩矿床的十个矿种(Fe、Fe-Cu、Pb-Zn、W、Sn、Sn-Mo-Bi-W、、W-Bi-Cu-Mo、Cu-Zn、Cu-Sn、W-Zn-Cu)和钙-镁夕卡岩矿床的三个矿种(Fe-Cu、Mo、Pb-Zn)。石榴子石和辉石成分变化范围大,大多数石榴子石是含锰铝榴石+铁铝榴石+镁铝榴石小于15％(摩尔百分数)的钙铝榴石-钙铁榴石固溶体;大多数辉石是含小于5％的锰钙辉石的透辉石-钙铁辉石固溶体。有些Pb-Zn钙-镁夕卡岩矿床中的辉石显示出Mn含量有所增加。只有Sn和W钙夕卡岩矿床及Pb-Zn钙-镁夕卡岩矿床含(Sps+Alm+Pyr)总量大于15％的石榴子石。石榴子石和辉石成分与夕卡岩矿床金属矿化类型之间有某些联系。     

都龙锌锡矿床夕卡岩石榴子石地球化学特征与成矿-找矿意义

都龙锌锡矿床是我国重要的锡锌铟资源基地,但其成因认识尚存在一定分歧。本文以含矿夕卡岩的主要矿物石榴子石为研究对象,在夕卡岩地质特征和矿物学特征研究基础上,通过石榴子石的主量-微量元素地球化学特征研究,表明该矿床石榴子石以钙铁榴石-钙铝榴石系列为主,石榴子石及含矿夕卡岩的形成均受燕山晚期花岗岩控制,揭示该矿床主要与燕山晚期岩浆热液活动有关,进而提出了深部及外围找矿方向。     

云南中甸红牛-红山大型夕卡岩铜矿床石榴子石U-Pb年代学、元素地球化学及地质意义

为厘定云南中甸红牛-红山大型夕卡岩铜矿床赋存矿体的夕卡岩的形成年龄，对矿区产出的石榴子石开展了U-Pb定年，并结合石榴子石的元素地球化学特征探讨矿床成因。结果显示，矿区不同矿段(红牛、红山)均发育早(GrtⅠ)、晚(GrtⅡ)两个世代的石榴子石，其成分均为钙铝-钙铁榴石固溶体(红牛为And_{27.02～62.53}Gro_{36.74～71.64},红山为And_{42.51～99.94}Gro_0.00～56.37)。不同矿段、不同世代石榴子石的稀土元素配分模式特征迥异，表现为左倾型、负Eu异常和右倾型、正Eu异常两种配分模式；两个矿段石榴子石的稀土总含量相差较大(红牛为5.29×10^-6～102×10^-6,红山为19.8×10^-6～206×10^-6)。研究表明，石榴子石的稀土配分模式主要受钙铝榴石-钙铁榴石端元组分控制；更高的稀土元素含量可能与富氯流体的加入及流体运移距离较短有关。红牛-红山矿床石榴子石U-Pb年龄为(79.7...     

云南双沟变质橄榄岩中蛇纹石的稀土元素空间分布

本文探讨变质橄榄岩的ＬＲＥＥ富集型及Ｕ型分布的ＲＥＥ球粒陨石模型，是橄榄石固有的还是后期蚀变形成的。并寻求复原蚀变前橄榄石的ＲＥＥ丰度及型式。我们用蛇纹石颗粒代表蚀变后的橄榄石，用分选法和化学分层剥离法对样品进行予处理。用中子活化分析（ＮＡＡ）手段进行了测试。结果表明：分选法确定了ＬＲＥＥ的主要赋存载体是蛇纹石。分层剥离最后内核的ＲＥＥ丰度及模型，可近似地作为原来（未蚀变前）橄榄石的ＲＥＥ丰度及模型。     

湘中地区中奥陶统沉积岩的稀土元素地球化学

湘中地区中奥陶统黑色岩系稀土元素地球化学特点为稀土丰度高轻稀土富集，重稀土亏损，无负Ｃｅ异常，Ｅｕ负异常明显并有高的∑ＬＲＥＥ/∑ＨＲＥＥ、Ｌａ/Ｙｂ、（Ｌａ/Ｙｂ）ｎ特征值等，是一种被动大陆边缘缺氧盆地的产物，其沉积物的稀土元素地球化学特点受沉积速率、搬运方式、物源供给等因素的影响。     

Geochemical Behaviors of REE and Other Trace Elements during the Formation of Strata-bound Skarns and Related Deposits: A Case Study of the Dongguashan Cu (Au) Deposit, Anhui Province, China

REE and other trace elements in the altered marbles, massive skarns and ores, as well as garnet and quartz were determined in order to examine the behaviors of trace elements during hydrothermal alteration. It is demonstrated that the high-field-strength (HFS) elements Zr, Hf, Th and Nb were immobile while other trace elements were mobile during the formation of skarns and related deposits. REE and ore-forming elements such as Cu and Ag in hydrothermally-altered marbles and skarns were provided primarily by hydrothermal fluids. In the direction transverse of the strata, the more deeply the marbles were altered, the higher the total REE abundance and the larger the negative Eu anomalies would be. The chondrite-normalized REE patterns of skarns are similar to those of the marbles, but the former are distinguished by much higher REE contents and more remarkable negative Eu anomalies. Those patterns were apparently not inherited from the marble protolith, but were controlled by garnets, which were determine     

The Rare Earth Elements and Uranium in Garnets from the Beinn an Dubhaich Aureole, Skye, Scotland, UK: Constraints on Processes in a Dynamic Hydrothermal System

Garnets from skarns in the Beinn an Dubhaich granite aureole,Isle of Skye, Scotland, have a large range of concentrationsof uranium (0·2–358 ppm) and the rare earth elements(REE) (23–4724 ppm). Variations in these concentrationscorrelate with major element zonation within the garnets, andwith changes in the shape of REE patterns. Typical patternsin most garnets display light REE (LREE) enrichment, flat heavyREE (HREE) distribution and a negative Eu anomaly. These patternsare interpreted to represent equilibrium trace element exchangebetween pre-existing pyroxene, hydrothermal fluid and calcicgarnets. Iron-rich zones are characterized by positive Eu anomaliesand an increase in the abundance of the LREE relative to theHREE. These patterns are interpreted as resulting from changesin REE speciation related to the introduction of externallybuffered fluid to the skarn system. Relatively Fe-poor zonesshow strongly HREE-enriched patterns with negative Eu anomaliesand in some instances depletions in Y relative to Ho and Dy,which are interpreted as resulting from surface sorption ofthe REE during rapid, disequilibrium garnet growth. Strong correlationsbetween U abundance and the REE patterns indicate that the sameprocesses have affected U distribution. Both types of patterncan be modified by the effects of closed-system crystallizationon REE abundance in the fluid, and changes in fluid major elementchemistry. KEY WORDS: fractionation; garnet; hydrothermal; rare earth elements; skarn     

新疆蒙库铁矿床稀土元素地球化学及对铁成矿作用的指示

新疆富蕴县蒙库大型铁矿呈层状、似层状、透镜状赋存于下泥盆统康布铁堡组变质火山-沉积岩系中.矿体中发育矽卡岩,但矽卡岩并不产在侵入岩接触带上.绿帘石、石榴石和矿石的稀土配分模式具有相似性,均为轻稀土富集,正铕异常,基本上无铈异常,暗示它们之间存在成因联系.石榴石稀土配分模式呈折线型,具有明显的正铕异常,石榴石流体包裹体中熔融包裹体、熔流包裹体和气液包裹体共存,表明石榴石矽卡岩具有岩浆成因和热液成因的特征,形成于晶体 熔体 流体三相共存的岩浆-热液过渡阶段.矿床地质特征、矽卡岩矿物和矿石稀土特征表明蒙库铁矿为矽卡岩型矿床.     

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.     

Rare earth elements in high-grade metamorphic rocks from the western Alps

A sequence of amphibolite to granulite facies metasedimentary and mafic metaigneous rocks from the western Italian Alps has been analysed for rare earth elements (REE). In this sequence, the metasedimentary granulites have probably been affected by a melting event while the metaigneous granulites remained unaffected. Metasedimentary granulites have a less fractionated chondrite-normalized REE pattern than equivalent amphibolite facies rocks. The granulites tend to have a higher content of heavy REE and lower abundances of light REE (LREE). The leucosomes of migmatitic granulites have lower REE content than the melanocratic bands and both these rock types have variable relative abundances of Eu. The mafic granulites have LREE enriched patterns while the amphibolites are slightly depleted in LREE. The differences between the mafic granulites and amphibolites are probably of pre-metamorphic origin.     

苏鲁皖新生代玄武岩中巨晶组合的稀土元素特征

我国东部苏鲁皖地区新生代碱性玄武岩中,除了含有大量地幔橄榄岩类捕虏体以外,尚含有一定数量的石榴石、普通辉石和歪长石巨晶。这些巨晶是在地幔不同深度上从玄武岩中晶出的。巨晶组合的分离结晶作用对熔体稀土元素含量有很大影响。赋存巨晶的碱性玄武岩所具有的LREE富集、HREE亏损的稀土元素分配型式是由地幔橄榄岩类部分熔融程度、石榴石巨晶和普通辉石巨晶的早期高压熔离和玄武岩的结晶分异作用等综合因素造成的。     

Mineral geochemistry of the Sangan skarn deposit,NE Iran: Implication for the evolution of hydrothermal fluid

The Sangan iron skarn deposit is located in the Sabzevar-Dorouneh Magmatic Belt of northeastern Iran. The skarn contains zoned garnet, clinopyroxene and magnetite. Cores and rims of zoned garnets are generally homogeneous, having a relatively high ΣREE, low ΣLREE/ΣHREE ratios, and positive Eu anomalies. The cores of the zoned clinopyroxenes are exceptionally HREE-rich, with relatively high ΣREE and HREE/LREE ratios, as well as positive Eu anomalies. Clinopyroxene rims are LREE-rich, with relatively low ΣREE contents and HREE/LREE ratios, and do not have Eu anomalies. Magnetite grains are enriched in LREEs in comparison with the HREEs and lack Eu anomalies. Variations of fluid composition and physicochemical conditions rather than YAG-type substitution mechanism are considered to have major control on incorporating trace elements, including REE, into the skarn mineral assemblage. Based on baro-acoustic decrepitation analysis, the calc-silicate and magnetite dominant stages were formed at similar temperatures, around 350–400 °C. In the Sangan skarns, hydrothermal fluids shifted from near-neutral pH, reduced conditions with relatively high ΣREE, low LREE/HREE ratios, and U-rich characteristics towards acidic, oxidized conditions with relatively low ΣREE, high LREE/HREE ratios, and U-poor characteristics.