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 determined by the hydrothermal solutions involved in the infiltration metasomatism. The hydrothermal fluids are characterized by having slightly right-hand dipping REE patterns, being enriched in LREE and having strongly negative Eu anomalies. The uptake of REE from hydrothermal fluids during the growth of garnet crystals resulted in the garnets having similar REE patterns to the hydrothermal fluids. Based on the spatial variation of REE in skarns and the structures of the hosting strata, we can get a better understanding of the transport path and pattern of the fluids involved in the formation of skarns and their related deposits. REE geochemistry investigation can help elucidate the genesis of skarns and skarn-related deposits.

Rare earth element(REE) geochemistry of different colored fluorites from the Baoshan Cu–Pb–Zn deposit, Southern Hunan,South China

The Baoshan Cu–Pb–Zn deposit, located in the central part of the Qin–Hang belt in South China, is closely related to the granodiorite-porphyry. However, the characteristics and the source of the ore-forming fluid are still ubiquitous. According to the crosscutting relationships between veinlets and their mineral assemblages, three stages of hydrothermal mineralization in this deposit were previously distinguished. In this contribution, two different colored fluorites from the major sulfide mineralization stage are recognized:(1) green fluorites coexisting with Pb–Zn ores;and(2) violet fluorites coexisting with pyrite ores. Y/Ho ratios verify the green fluorites and violet fluorites were co-genetic. The fluorites display elevated(La/Yb)Nratios, which decrease from 1201 to 5710 for green fluorites to 689–1568 for violet fluorites, indicating that they precipitated at the early hydrothermal sulfide stage,and Pb–Zn ores crystallized earlier than pyrite ores. The similar Tb/La ratios of the fluorites also indicate that they precipitated at an early stage within a short time. From the green fluorites to violet fluorites, the total rare earth element(ΣREE)concentrationsdecreasefrom1052–1680 ppm to 148–350 ppm, indicating that the green fluorites precipitated from a more acidic fluid. The Eu/Eu*ratios increase from 0.17 to 0.30 for green fluorites to0.29–0.48 for violet fluorites, and the Ce/Ce* ratios decrease from 1.08–1.13 to 0.93–1.11, suggesting a gradual increase in oxygen fugacity(fO_(2)) and pH value of the mineralization fluid. Though the fluorites display similar REE patterns to the granodiorite-porphyry and limestone,the ΣREE concentrations of the fluorites are significantly higher than those of limestone and the granodiorite-porphyry, suggesting that an important undetected non-magmatic source is involved to provide sufficient REE for fluorites. The most plausible mechanism is fluid mixing between magma fluid and an undetected non-magmatic fluid.

Geochemistry of Subvolcanic-Type Copper-Silver Deposits in Eastern China

The metallogenesis of subvolcanic deposits is controlled by subvolcanic activities. The copper polymetallic deposits are genetically related to intermediate-acid rocks, and the silver polymetallic deposits are more closely related to acid rocks. The abundance of Cu is relatively high in the intermediate-acid rocks and subvolcanic rocks, whereas the abundances of Pb, An and Ag are high in acid rocks, indicating rich ore-forming elements in original magmas. The study of REEs shows that the magmatic type related to copper deposits is the syntectic type, and that related to silver polymetallic deposits is mainly the re-melting type. The deposits were formed under medium-low temperatures and low salinity. The metallogenic times were the late stage of the early Yanshanian or the late Yanshanian, dating 78–147 Ma.

Geochemistry Characteristics of Granodiorite Porphyry in the Degongniuchang Copper Deposit, Muli, Sichuan Province, China

1 Introduction 1The Sanjiang region in SE Tibet Plateau and NW Yunnan is known to have formed by amalgamation of Gongwanaderived continental blocks and arc terranes as a result of oceanic subduction followed by continental

Geotectonic Settings of Large and Superlarge Mineral Deposits on the Southwestern Margin of the North China Plate

The geotectonic setting refers to the three-dimensional space and relatedevents based on which a metallogenic system is formed and an ore-forming process takes place. Thispaper discusses the tectonic evolution of the southwestern margin of the North China paleocontinentand related geotectonic settings in which large or superlarge deposits are formed. Emphasis is puton the geodynamic conditions of the Jinchuan nickel-copper deposit, the Baiyin copper-polymetallicdeposit and the Hanshan gold deposit. It is significant that the three deposits occur together as a'trinity' on the same paleocontinental margin. The Jinchuan nickel-copper deposit was formed duringthe early stage of rifting of the paleocontinental margin; the Baiyin copper-polymetallic depositwas formed during the splitting stage of a continental-margin arc. The continental-margin arcspitting resulted in an 'island arc rift' in the early stage of evolution. The Hanshan gold depositwas formed within the Altun sinistral strike-slip fault system and its provenance is the'intraoceanic arc' volcanic rocks.

哈西哇地区铜镍元素地球化学特征及找矿前景

哈西哇地区属东昆仑伯喀里克-香日德印支期金、铅、锌、铁、铜、镍(稀有、稀土)成矿带,随着勘查程度的提高,成矿较为显著。根据区域地质学研究,早中泥盆世构造岩浆阶段为碰撞晚期(后碰撞)构造环境,整个东昆仑西段表现为持续性的伸展体制,岩浆活动(特别是幔源岩浆活动)极为强烈,东昆仑地区铜镍矿床就是在这种岩石圈构造伸展环境下,大量幔源岩浆深部熔离和上侵贯入形成的产物,即夏日哈木等区成矿作用的具体体现。本文通过对哈西哇地区地球化学特征及找矿前景分析研究,得出一定找矿前景。

超镁铁岩的REE特点及其对青海德尔尼铜钴矿的成因意义

不同成因的超镁铁岩具有不同的ＲＥＥ特点。与硫化镍矿有关的侵入超镁铁岩有较高的ＲＥＥ含量，富集轻稀土；蛇绿岩套中的变质橄榄岩ＲＥＥ含量较低，以“Ｕ”型或轻稀土亏损型为特点。德尔尼超镁铁岩体有变质橄榄岩的ＲＥＥ特征，属蛇绿岩套的一部分，为地幔物质低度部分熔融的产物，部分熔融程度约为５％。德尔尼铜矿属火山成因的块状硫化物矿床，由于构造作用致使矿体产于超镁铁岩中。阿尼玛卿山地区铜钴矿的找矿方向是原布青山群和部分三叠系中玄武岩－硅质（碳质）板岩出露地区。

金川铜镍矿床年龄和源区同位素地球化学特征

本文报道了金川铜镍硫化物矿床 Sm- Nd、Rb- Sr、Re- Os同位素年龄测定结果 ,讨论了矿床物质源区。金川铜镍矿床 Re- Os年龄为 10 4 3± 2 8(2 σ) Ma,IOs=0 .15 0 3± 5 0 (2 σ) ;Sm- Nd等时年龄约 0 .97± 0 .31(2 σ)Ga,INd=0 .5 110 6± 2 8(2 σ) ;Rb- Sr等时年龄约 819Ma,ISr=0 .7118。矿床物质来自富集地幔源区。

江西新余铁矿的地球化学特征及其与华北BIFs铁矿的对比

本文报道了新余和华北BIF铁矿的主量元素、微量元素、稀土元素的测试结果:新余和华北地区BIF铁矿的化学成分均主要由Fe2O3T和SiO2组成,它们的页岩标准化稀土元素配分曲线均呈现轻稀土亏损、重稀土富集的分馏模式。与华北BIF相比,新余铁矿具有更高的Al2O3和TiO2含量、微量元素含量、稀土总量,以及更低的Eu异常和Y/Ho比值,这些特征均表明,与华北地区相比,高温热液对新余地区BIF的贡献不明显。铁矿无明显的Ce负异常和Fe同位素组成为正值的特征暗示了铁矿沉淀时的海水为低氧逸度环境。

铜陵狮子山矿田金矿床和铜矿床矿石稀土元素地球化学

在全面收集前人有关安徽铜陵狮子山矿田主要矿床矿石和蚀变岩石稀土元素分析结果的基础上,对比研究了矿田内金矿床和铜矿床的稀土元素地球化学特征。研究表明,金矿床和铜矿床矿石和蚀变岩石的稀土元素组成、轻重稀土比值和(La/Yb)N值等特征参数承袭了矿区岩浆岩的特征,显示成矿物质的来源以岩浆来源为主,富集地壳组分,反映在成矿过程中深部热液对已固结岩浆岩的淋滤萃取作用和对沉积围岩的叠加改造作用,成矿作用与岩浆作用密切相关;不同成矿阶段和不同类型矿石或蚀变岩石的REE特征反映REE的来源和演化可能与成矿金属元素的来源及其富集成矿机制相一致。此外,金矿床和铜矿床矿石稀土元素地球化学行为亦显示出明显的差异性,铜矿床矽卡岩阶段矿石比石英硫化物阶段矿石相对低的REE含量,以及部分矽卡岩矿石具有La,Ce明显亏损的富集LREE折线型配分模式,反映铜矿床这部分矽卡岩具有岩浆成因的特征;而金矿床和部分铜矿床中的矽卡岩及矽卡岩型矿石则以热液交代成因为主;金矿床和铜矿床Eu异常特征则反映了其成矿热液流体起源压力的差异及流体性质的阶段性演化。

羊拉地区含矿矽卡岩成因的地球化学证据

滇西北羊拉铜矿化集中区现已发现４个矽卡岩体，按成因分为喷流－沉积和接触交代矽卡岩两大类，前者呈层状，是铜的主要赋矿围岩．不同成因的矽卡岩具有不同的岩石化学组成，其中喷流－沉积矽卡岩有贫Ａｌ２Ｏ３，ＴｉＯ２，ＲＥＥ和富铁（ＴＦｅＯ）等特征．在ｗ（ＴｉＯ２）－ｗ（Ａｌ２Ｏ３），ｗ（ＳｉＯ２）－ｗ（Ａｌ２Ｏ３），Ｎ（Ｆｅ）／Ｎ（Ｔｉ）－Ｎ（Ａｌ）／Ｎ（Ａｌ＋Ｆｅ＋Ｍｎ），ｗ（ＳｉＯ２）／２－ｗ（ＴＦｅＯ）－ｗ（ＣａＯ），ｗ（Ａｌ）－ｗ（Ｆｅ）－ｗ（Ｍｎ）和ｗ（Ａｌ２Ｏ３）－ｗ（ＴＦｅＯ）－ｗ（ＣａＯ）等多种岩石化学图解中喷流－沉积矽卡岩显示出与交代矽卡岩有较大的差别，前者的数据点多落在热水沉积区，而后者的数据点则多分布在大理岩与岩浆岩（中基性火山岩和花岗闪长岩）之间；喷流－沉积矽卡岩的稀土分布形式与现代大洋中脊热水沉积物相似，而交代矽卡岩则更接近于相关的侵入岩．

新疆喀拉通克铜镍硫化物矿床Y9岩体年代学与成岩成矿机制探讨

新疆喀拉通克是中国大型铜镍硫化物矿床中基性程度最低的,显示出罕见的Cu平均品位大于Ni平均品位。矿区划分为南、北2个岩带,南岩带主要为原生矿,北岩带主要为氧化矿。文章研究对象为北岩带中的Y9岩体,近年发现其下部存在原生矿石。通过单颗粒锆石SHRIMP测年,获得Y9岩体中辉长岩的结晶年龄为(287±4)Ma,与Y1岩体的成岩年龄〔(287±5)Ma〕一致,结合岩石地球化学和同位素地球化学特征,证明喀拉通克矿区南、北岩带具有同期同源岩浆演化的特征,岩浆源自亏损型地幔部分熔融与不含沉积物消减板片脱水物质的混合。研究认为喀拉通克铜镍矿床形成于亏损地幔在相对较高的氧逸度条件下低程度部分熔融,产生硫化物不饱和的岩浆,岩浆源区相对富水和较高的氧逸度,原始岩浆具有较高的钛含量,具有富碱亲合性。

云南大红山铜铁矿床稀土元素地球化学特征初探

文中主要选取大红山铜铁矿床典型穿脉进行构造-岩石地球化学编录,系统取样并对样品稀土元素进行化验分析。研究表明：（1）该矿区内各类岩（矿石）从矿化构造岩→矿石→未矿化构造岩的稀土总量呈现出逐渐降低的趋势,反映出成矿流体与不同构造岩的水岩反应程度上的差异。（2）从（La∕Yb）N看,该矿区内同类断裂构造岩的轻稀土分异程度较大,但不同断裂构造岩间的分异性却较为均一,从该区围岩、矿石、构造断裂岩的LREE∕HREE与（La∕Yb）N比值特征中可以看出,轻稀土元素与重稀土元素间的分异程度具有一定的相似性,反映出成矿流体对地层岩石存在着一定的继承性,却又具有一定的阶段演化性特征。（3）从地层岩石→未矿化断裂构造岩→矿化断裂构造岩→块状、条带状矿石,LREE∕HREE（5.66-13.27）有逐渐增大的趋势,反映出在断裂构造作用过程中,稀土元素发生了迁移;该矿区内各类岩（矿）石的δEu均大于1,δCe弱负异常,显示出大红山铜铁矿床的成矿作用主要是在相对氧化的环境下进行。

中国云南易门式铜矿床的主要类型及成因(英文)

系统地概括了易门铜矿田的成矿地质背景及2种矿床类型的地质特征,在此基础上论证了火山热水沉积作用、构造改造作用、岩浆叠加作用、地下热水再造作用与成矿密切相关。易门式铜矿床为"裂谷成矿背景-火山热水沉积-构造改造富集-深源岩浆叠加-地下热水再造"型多因复成矿床,建立了新的成矿模式,为该类矿床深部及外围的找矿预测指明了方向。

中国东部中生代陆相次火山岩型铜银矿床成矿地球化学特征

次火山岩型矿床的成矿作用受次火山活动控制。铜多金属矿床与中酸性岩类有成因联系,银多金属矿床与酸性岩类关系更密切。中酸性火山—次火山岩Cu的丰度值较高,酸性岩类Pb、Zn、Ag丰度值高,各自代表原始岩浆为富含矿源质的。稀土元素表明,与铜矿有关的岩浆为同熔型,而与银多金属矿有关的为地壳重熔型。矿床是在中低温、低盐度条件下形成的。其成矿时代为燕山早期晚阶段或燕山晚期。

陕西柞山地区穆家庄铜矿稀土元素地球化学特征

尽管秦岭泥盆系铅锌金多金属成矿带成矿作用均与热水喷流沉积作用有关,柞山地区却有别于凤太地区,具有独特的铜矿成矿背景。本文通过对矿床的岩、矿石稀土元素地球化学研究,认为浸染状贫铜矿石和近矿围岩的稀土组成和配分曲线基本一致,表明浸染状贫铜矿石代表了泥盆纪时期热水沉积事件所形成的含少量硫化物的热水沉积岩初步富集的产物,泥盆纪时期形成了穆家庄铜矿的初始矿源层。围岩中的层纹状硅质岩可能代表了泥盆纪时期的热水沉积岩性质。块状富矿石的稀土组成代表了广泛的陆陆碰撞造山运动所产生的流体热液作用的结果,它既就地改造了初始矿源层,而且从异地可能带来了部分成矿物质,在合适的构造部位改造富集成矿。穆家庄铜矿的成因为改造型的。

东天山天宇铜镍硫化物矿床磁黄铁矿Re-Os同位素物质来源示踪

天宇岩浆铜镍硫化物矿床的矿体由浸染状矿体和块状矿体组成。采用同位素稀释Triton-plus测定了浸染状矿石和块状矿石的磁黄铁矿Re-Os同位素比值。结果表明:浸染状矿石w(Re)为11.82×10^(-9)~45.28×10^(-9),w(Os)为0.944×10^(-9)~8.528×10^(-9),187Os/188Os初始比值为0.885~2.332,γOs为607~1763;块状矿石w(Re)为49.38×10^(-9)~315.10×10^(-9),w(Os)为0.191×10^(-9)~42.420×10^(-9),187Os/188Os初始比值为0.654~3.322,γOs为423~2555。Re、Os含量、同位素组成和特征值表明,该矿床物质为壳-幔混合来源,块状矿石可能比浸染状矿石经历了更强的地壳物质混染。浸染状矿体发育透闪石化、蛇纹石化、绿泥石化蚀变,表明存在岩浆期后热液活动,但块状矿体热液蚀变不明显,块状矿石的Re-Os同位素特征可能是与地壳岩石直接作用的结果。地壳混染作用发生在深部岩浆房,同时也发生在岩浆侵位及再次迁移过程中,这些过程造成块状矿体与浸染状矿体不同的同位素特征。

红旗岭矿床茶尖矿区铂族元素地球化学特征及其意义

以红旗岭铜镍硫化物矿床茶尖矿区1号和9号岩体为研究对象,进行了岩石化学特征分析、微量元素分析和稀土元素(REE)分析,重点研究了其铂族元素(PGE)地球化学特征。REE分析结果表明,岩石富集轻稀土元素,且有微弱的铕负异常。PGE富集在硫化物含量高的岩石中,与硫化物含量呈正相关关系。岩石中PGE分异明显,富集Rh、Pt和Pd。推测该区的基性-超基性岩形成于硫不饱和玄武质岩浆的演化,岩浆有地壳物质混染的特征,其成矿物质来源于上地幔,主要成矿机制为深部熔离-贯入作用。

金川铜镍硫化物矿床两类矿石的稀土元素地球化学特征研究

文章对金川铜镍硫化物矿床的网状富矿石和星点状贫矿石的稀土元素地球化学特征进行了研究,结果表明:网状富矿石的稀土元素含量低于星点状矿石,这可能与矿石中硫化物及橄榄石含量有关;网状富矿石的δEu差别大,结合矿石显微照片的结构特征,说明其岩浆演化环境比较复杂,应该处于缓慢冷凝的早期深部熔离成矿作用阶段;而星点状矿石样品的稀土元素标准化分布曲线相似,结合矿石显微照片的结构特征,指示其应该形成于快速冷凝的晚期就地熔离成矿作用。此外,两者的轻、重稀土元素分馏程度相当,这否定了贫矿岩浆与富矿岩浆之间的演化关系,揭示了原始岩浆分层后,各层岩浆是独立演化并成矿的。

我国铜镍硫化物矿床的稀土元素地球化学特征

我国铜镍硫化物矿床成矿岩体的稀土元素地球化学特征与其产出的构造环境及含矿性密切相关。地槽区岩体的稀土元素含量及多种参数相对较低，主要与其起源于俯冲洋壳较大比例重熔有关。同一环境中富矿岩体较贫矿岩体的稀土元素含量及多种参数比值相对较高，则与其所经历的深部岩浆分异程度较高有密切关系。因而依据岩体稀土元素地球化学特征，可推断其铜镍含矿性。