Fluid Inclusion Studies and Geochemistry of Rare Earth Elements of Hydrothermal Fluorites from Pohrenk, Kirsehir, Central Turkey

Fluorite mineralization occurs along fractures and cracks of Middle Eocene and Pliocene limestones and marls in the north and northeast of the Pohrenk region (Qicekdagi, Kirsehir). Tb/Ca - Tb/La and Y/Ho ratios were obtained from REE contents of fluorites which have revealed that mineralization is of hydrothermal type. Negative Ce anomalies and positive Eu anomalies reflect that hydrothermal solutions once had high oxygen fugacity. Fluid inclusion studies indicate that homogenization temperatures of mineralization varied between 90℃ and 200℃, and hydrothermal solutions are composed of NaCl + KCl + MgCl2 + H2O. In addition, salinity measurements show that hydrothermal solutions were mixed with meteoric or rock formation water. Geologic setting, REE geochemistry and fluid inclusion studies suggest that mineralization was deposited from a solution generated by mixing of magmatic and meteoric water under epithermal conditions.     

Fluid Inclusion Studies and Geochemistry of Rare Earth Elements of Hydrothermal Fluorites from Pöhrenk,Kirşehir,Central Turkey

Fluorite mineralization occurs along fractures and cracks of Middle Eocene and Pliocene limestones and marls in the north and northeast of the Pöhrenk region (Çiçekdagi, Kirsehir). Tb/Ca – Tb/La and Y/Ho ratios were obtained from REE contents of fluorites which have revealed that mineralization is of hydrothermal type. Negative Ce anomalies and positive Eu anomalies reflect that hydrothermal solutions once had high oxygen fugacity. Fluid inclusion studies indicate that homogenization temperatures of mineralization varied between 90°C and 200°C, and hydrothermal solutions are composed of NaCl + KCl + MgCl₂ + H₂O. In addition, salinity measurements show that hydrothermal solutions were mixed with meteoric or rock formation water. Geologic setting, REE geochemistry and fluid inclusion studies suggest that mineralization was deposited from a solution generated by mixing of magmatic and meteoric water under epithermal conditions.     

西秦岭寨上金矿床地球化学特征 及成因机制研究

寨上金矿床共发现金矿脉22条,金矿体19条.通过氢、氧同位素分析得出:该区成矿流体水具有多来源特征.δ34S的组成特点可能反映了硫源为岩浆硫和地层硫的混合.碳的来源主要由海相沉积碳酸盐岩经溶解作用和花岗岩岩浆热液提供.矿石稀土元素并没有完全继承围岩的特征.成矿流体具有以下特征:成矿流体为中低温、低盐度、低密度、多期次活动的流体.金矿成矿是在300Ma之后燕山晚期形成的.成矿热液中,金主要以硫化物配合物的形式迁移.成矿流体与围岩发生充分的物质交换后.运移到裂隙发育部位,并因为流体的混合和围压突然降低,成矿流体产生强烈的沸腾作用,使成矿物质沉淀富集成矿.     

山东省东明地热田地球物理化学特征分析

山东省东明地热田内蕴藏着丰富的地热资源,通过已有地质资料及近年的勘查项目研究成果,对东明地热田的地热资源的地质背景、热储特征,地球物理化学特征等进行了研究分析,认为东明地热田属干层控型低温地热田,热储层主要为新近纪明化镇组下部、馆陶组、古近纪东营组地层,该区的地温梯度主要受构造控制,断裂导热是形成该地温场的一个重要因素,地下热水水平方向水化学组分变化甚微,具有明显的垂直分带性,地热水水源主要为渗入的溶滤水.     

滇西北衙金多金属矿床成矿地球化学特征

北衙金多金属矿床是金沙江-哀牢山-红河断裂带与新生代富碱斑岩有关的斑岩型矿床之一.本文重点提供了流体包裹体中稀土微量元素和矿石S、Pb同位素分析结果,并对成矿流体及成矿物质来源等问题进行了讨论.研究表明,本区流体包裹体稀土总量较低,∑REE介于5.19×10-6～9.0×10-6之间,反映轻重稀土分馏程度的∑LREE/...     

Fluid Inclusion, Rare-Earth Element and Stable Isotope Study of Carbonate Minerals from the Pongkor Epithermal Gold–Silver Deposit, West Java, Indonesia

The Pongkor gold–silver deposit is the largest low‐sulfidation epithermal precious metal deposit in Indonesia, and is of Pliocene age. The deposit consists of nine major subparallel quartz–adularia–carbonate veins with very low sulfide content. Vein infill records five paragenetic sequences, dominated by calcite in the early stage and quartz in the later stage of the hydrothermal evolution. Fluid inclusions in hydrothermal calcite and quartz of all stages indicate a temperature ranging from 180 to 220°C and a meteoric water origin (very low salinity close to 0 wt% NaCl equivalent). Carbon isotope data on calcite display a narrow range from ?6.5 to ?3.0‰δ¹³C. The oxygen isotope values have a wider range of +4.6 to +10.1‰δ¹⁸O. The broadly positive correlation of the δ¹³C versus δ¹⁸O plot suggests that the carbon species, which equilibrated during the formation of calcite, is dominated by H₂CO₃ not far from equilibrium with HCO₃^?. The abundance of rare earth and yttrium (REY) in carbonate samples is very low (>REY mostly <2 ppm). However, there is always a positive Eu anomaly, which indicates a deeper fluid reservoir at >250°C.     

广西德保铜矿床成因探讨

德保铜矿矿体主要赋存于花岗岩外接触带的寒武系碳酸盐岩岩层中,受后期断裂构造破坏明显.矽卡岩化岩(矿)石中Au、Ag、As、Bj、Sb等微量元素含量明显高于其他岩石,显示矽卡岩化作用是导致该区微量元素富集的主要原因.相同岩(矿)石的稀土元素配分曲线十分相似,不同岩(矿)石则差异很大,但稀土元素的总体特征显示铜矿化与花岗岩...     

Implication of Apatite and Anhydrite for Formation of an Iron‐Oxide‐Apatite (IOA) Rare Earth Element Prospect,Benjamin River,Canada

The Benjamin River apatite prospect in northern New Brunswick, Canada, is hosted by the Late Silurian Dickie Brook plutonic complex, which is made up of intrusive units represented by monzogranite, diorite and gabbro. The IOA ores, composed mainly of apatite, augite, and magnetite at Benjamin River form pegmatitic pods and lenses in the host igneous rocks, the largest of which is 100 m long and 10–20 m wide in the diorite and gabbro units. In this study, 28 IOA ore and rock samples were collected from the diorite and gabbro units. Mineralogical observations show that the apatite–augite–magnetite ores are variable in the amounts of apatite, augite, and magnetite and are associated with minor amounts of epidote‐group minerals (allanite, REE‐rich epidote and epidte) and trace amounts of albite, titanite, ilmenite, titanomagnetite, pyrite, chlorite, calcite, and quartz. Apatite and augite grains contain small anhydrite inclusions. This suggests that the magma that crystallized apatite and augite had high oxygen fugacity. In back scattered electron (BSE) images, apatite grains in the ores have two zones of different appearance: (i) primary REE‐rich zone; and (ii) porous REE‐poor zone. The porous REE‐poor zones mainly appear in rims and/or inside of the apatite grains, in addition to the presence of apatite grains which totally consist of a porous REE‐poor apatite. This porous REE‐poor apatite is characterized by low REE (<0.84 wt%), Si (<0.28 wt%), and Cl (<0.17 wt%) contents. Epidote‐group minerals mainly occur in grain boundary between the porous REE‐poor apatite and augite. These indicate that REE leached from primary REE‐rich apatite crystallized as allanite and REE‐rich epidote. Magnetite in the ores often occurs as veinlets that cut apatite grains or as anhedral grains that replace a part of augite. These textures suggest that magnetite crystallized in the late stage. Pyrite veins occur in the ores, including a large amount of quartz and calcite veins. Pyrite veins mainly occur with quartz veins in augite. These textures indicate pyrite veins are the latest phase. Apatite–augite–magnetite ore, gabbro–quartz diorite and feldspar dike collected from the Benjamin River prospect contain dirty pure albite (Ab₉₈Or₂–Ab₁₀₀) under the microscope. The feldspar dikes mainly consist of dirty pure albite. Occurrences of the dirty pure albite suggest remarkable albitization (sodic alteration) of original plagioclase (An_25.3–An₆₀ in Pilote et al., 2012) associating with intrusion of monzogranite into gabbro and diorite. SO₄^2? bearing magma crystallized primary REE‐rich apatite, augite and anhydrite reacted with Fe in the sodic fluids, which result in oxidation of Fe²⁺ and release of S^2? into the sodic fluids. REE, Ca and Fe from primary REE‐rich apatite, augite and plagioclase altered by the sodic fluids were released into the fluids. Then Fe³⁺ in the sodic fluids precipitated as Fe oxides and epidote‐group minerals in apatite–augite–magnetite ores. Finally, residual S^2? in sodic fluids crystallized as latest pyrite veins. In conclusion, mineralization in Benjamin River IOA prospect are divided into four stages: (1) oxidized magmatic stage that crystallized apatite, augite and anhydrite; (2) sodic metasomatic stage accompanying alteration of magmatic minerals; (3) oxidized fluid stage (magnetite–epidote group minerals mineralization); and (4) reduced fluid stage (pyrite mineralization).     

塔里木盆地中寒武统泥晶白云岩红层的地球化学特征与成因探讨

塔里木盆地西部克拉通台地区寒武系中寒武统发育大量泥晶白云岩红层。钻孔岩芯观察及岩石学分析表明,该白云岩以岩芯呈暗红色、显微镜下呈泥粉晶结构、并伴随有纤状石膏假晶与陆源石英碎屑为主要特征,指示了该白云岩形成于潮上带蒸发环境。地球化学分析结果表明,该白云岩具有固有属性的CaO％,MgO％含量正相关特征, 因此,塔里木盆地中寒武统泥晶白云岩红层属于典型的潮上带Sabkha型沉积的“原白云石”。泥晶白云岩红层U,Mo含量亏损,指示了该白云岩形成于氧化环境,与色泽较红相一致;稀土元素特征上,该泥晶白云岩红层稀土元素配分模式呈右倾特征,但是在陆源碎屑的影响下,常出现中稀土元素富集的“帽”型特征;碳氧同位素分析表明,泥晶白云岩红层碳同位素变化没有规律性,多数δ18OPDB值变化在-7‰~-4.4‰之间,与潮上带蒸发沉积的Sabkha特征一致;英买7井白云岩红层δ18OPDB值较低（＜-10‰）,可能为成岩作用过程中热液改造的结果;由于泥质矿物的存在,潮上带白云岩87Sr/86Sr比值一般比同期海水值偏高。     

西藏努日铜钼钨矿床辉钼矿微量元素、稀土元素地球化学特征——对矿床成矿流体性质的约束

为厘清努日铜钼钨矿床的成矿时代,以矿床中的辉钼矿为研究对象,用ICP-MS分析方法,开展了稀土元素和微量元素地球化学研究。结果显示,辉钼矿具有典型的轻重稀土分馏、轻稀土元素(LREE)富集的右倾配分模式,辉钼矿稀土元素具有强烈的Ce负异常和Eu负异常,前者可能为成矿流体本身具有高温高氧逸度导致,后者可能是与矽卡岩矿化有密切关系的黑云母花岗闪长岩浆在分离结晶过程中大量的斜长石晶出引起的,同时岩体蚀变过程中对成矿流体体系亏损铕有一定贡献。辉钼矿中Pb、Ba、V、Ni、Sr、Rb含量相对较高,U、Th含量非常低,Hf/Sm、Th/La远小于1,Nb/La远大于1,表明成矿流体早期以富F的来自于深部幔源的岩浆热液为主,而Y/Ho、Zr/Hf、Nb/Ta变化范围存在不同幅度的差异。表明主成矿期成矿流体在该阶段不同程度的混入了部分外来流体而富Cl,但总体特征仍以早期成矿流体为主。     

山东荣成马草夼橄榄岩矿物地球化学研究

马草夼橄榄岩位于苏鲁超高压变质带山东荣成腾家集附近,其原岩为残余地幔方辉橄榄岩,经历了超高压变质作用和后期麻粒岩-角闪岩相变质作用.对马草夼橄榄岩及侵入于其中的辉石岩脉和角闪岩脉的主要矿物橄榄石、斜方辉石和角闪石做了单矿物微量元素和稀土元素地球化学分析,结果表明Co和Ni在橄榄石中含量最高且富集,在斜方辉石和角闪石中含量低且亏损.由于橄榄石在全岩中含量高达90%以上,因而全岩Co、Ni富集.虽然角闪石在全岩中体积含量仅占3%～8%,但斜方辉石和橄榄石的微量和稀土元素含量远远低于角闪石,故全岩的微量(Co、Ni除外)和稀土元素化学特征受控于角闪石.斜方辉石、橄榄石与角闪石的微量和稀土元素分布特征基本相同,辉石岩脉和角闪岩脉中的角闪石比地幔橄榄岩中的角闪石更富集微量和稀土元素.微量和稀土元素地球化学特征显示马草夼橄榄岩至少受到了含Co、Ni的流体,富含LREE、Ba、Sr、Ta的硅酸盐流体和少量低Th、U的碳酸盐地幔流体的多次交代,流体交代发生于超高压变质后期浅部地幔驻留期间.马草夼橄榄岩所处的氧逸度(相对于FMQ)为+1.0～+2.0,落入正常大陆地幔的范围,在折返过程中未受到壳源流体的影响,保持了地幔氧同位素特征.     

Carbonation of Cl-rich scapolite boudins in Skallen, East Antarctica: evidence for changing fluid condition in the continental crust

Spectacular reaction textures in poikiloblastic scapolitite boudins, within marbles in the continental crust exposed in the Lützow–Holm Complex, East Antarctica, provide insights into the changing fluid composition and movement of fluid along grain boundaries and fractures. Petrographic and geochemical features indicate scapolite formation under contrasting fluid compositions. Core composition of scapolite poikiloblasts (Scp_I) are marialitic (Cl = 0.7 apfu) whereas rims in contact with biotite or clinopyroxene are meionite rich. Fine‐grained recrystallized equigranular scapolite (Scp_II) shows prominent chemical zoning, with a marialitic core and a meionitic rim (Cl = 0.36 apfu). Scapolite poikiloblasts are traversed by Scp_III reaction zones along fractures with compositional gradients. Pure CO₂ fluid inclusions are observed in healed fractures in scapolite poikiloblasts. These negative crystal‐shaped fluid inclusions are moderately dense, and are believed to be coeval with Scp_III formation at temperatures >600 °C and a minimum pressure of c. 3.8 kbar. Grain‐scale LA‐ICPMS studies on trace and rare earth elements on different textural types of scaplolites and a traverse through scapolite reaction zone with compositional gradient suggest a multistage fluid evolution history. Scp_I developed in the presence of an internally buffered, brine‐rich fluid derived probably from an evaporite source during prograde to peak metamorphism. Recrystallization and grain size reduction occurred in the presence of an externally sourced carbonate (CaCO₃)‐bearing fluid, resulting in the leaching of Cl, K, Rb and Ba from Scp_I along fractures and grain boundaries. Movement of fluids was enhanced by micro‐fracturing during the transformation of Scp_I to Scp_III. Fractures in fluorapatite are altered to chlorapatite proving evidence for the pathways of escaping Cl‐bearing fluids released from Scp_I. The present study thus provides evidence for the usefulness of scapolite in fingerprinting changing volatile composition and trace element contents of fluids that percolate within the continental crust.     

青海西宁城南新区杜家庄地热田地下水的地球化学特征

依据青海省西宁市城南新区杜家庄地热田DR2005地热井地下热水的水化学资料,采用兰格利厄—路德维金图解法、同位素水文学方法、地球化学温标法等,对杜家庄地热田地下热水的补给机制、地下热水年龄、地热资源潜力等关键问题进行分析。分析结果表明杜家庄地热田地下热水源于大气降水入渗补给,但仍有现代冷水补给,地热田下部还存在着远高于DR2005地热井开采段温度的热储。依据研究区地热地质条件具可比性的地热生产井水化学动态观测资料推断,随着DR2005地热井开采时间的延续,地下热水水质将向淡化的方向发展。研究结果为杜家庄地热田的开发利用提供水文地球化学依据。     

Coexistence of a Fluid Phase with Granitic Magma: Geochemical Characteristics of REE and Cu in Miyako Granite and in Scheelite-bearing Aplitic Veins at the Yamaguchi Cu-W Skarn Deposit, Iwate, Japan

Abstract: The North granitic body of the Miyako pluton is located in the Northern Kitakami belt, Northeast Japan. The formation of the scheelite–chalcopyrite–magnetite–bearing aplitic veins and scheelite–chalcopyrite–magnetite–bearing Yamaguchi skarn deposit was closely associated with the formation of the Miyako plutons. Petrographic facies of the North granitic body vary from quartz diorite in marginal zone (zone A), to tonalite and granodiorite (zone B), and to granite (zone C) in the central. The large numbers of aplitic veins distributed around the Yamaguchi mining area are divided into two groups: barren and scheelite–mag–netite–chalcopyrite–bearing aplitic veins. The latter cut massive clinopyroxene skarns of the Yamaguchi deposit, and are composed of plagioclase, K‐feldspar and titanite. Some plagioclase crystals have dusty cores with irregularly shaped K‐feldspar flakes, and clear rims of albite. Textures of plagioclase in the mineralized aplitic veins are different from the idiomorphic textures with sharp plagioclase crystal boundaries that occur in the North granitic body and barren aplitic veins. These textural data suggest that the mineralized aplitic veins were formed from hydrothermal fluid. Changes in the contents of major and minor (Rb, Sr, Sc, Co, Th, U) elements in the North Miyako granitic body are similar to those of zoned plutons formed by typical magmatic differentiation processes. On the other hand, concentrations of REE, especially middle to heavy REE, of granitic rocks in zone C and barren aplitic veins are significantly lower than those of granitic rocks in zones A and B. The hypothetical chondrite‐normalized REE patterns, calculated assuming fractional crystallization from zone B granitic melt, suggest that REE concentrations of the residual melt increased with the degree of fractional crystallization, and changed into a pattern with enriched LREE and strongly negative Eu anomaly. However, the REE patterns of granitic rocks in zone C are different from the hypothetical patterns. Moreover, the REE patterns of magnetite–scheelite–chalcopyrite aplitic veins are quite different from those of granitic rocks. The Cu contents of granitic rocks in the North Miyako body increase from zone A (5–26 ppm) to zone B (10–26 ppm), and then clearly decrease to zone C (5–7 ppm) and drastically increase to the barren aplitic veins (39–235 ppm). Concentrations of Cu in the mineralized aplitic veins are also higher than those of the granitic rocks in zone C. The decrease in REE and Cu contents of granitic rocks from zone B to zone C is not a result of simple magmatic fractional differentiation. Fluid inclusions in quartz from mineralized aplitic veins contain 3.3 wt% NaCl equivalent and 5.8 wt% CO₂. It was also demonstrated experimentally that the removal of MREE and HREE by fluid from melt enabled the formation of complexes of REE and ligands of OH^‐ and CO₃^2‐. Based on the possibility that the melt of the granitic rocks of zone C and the mineralized aplitic veins coexisted with CO₂‐bearing fluid, it is thought that REE were extracted from the melt to the CO₂‐bearing fluid, and that the REE in the mineralized aplitic veins were transported by the CO₂‐bearing fluid. It is likely that the low HREE and Cu contents of the granitic rocks in zone C could have been caused by the removal of those elements from the granitic melt by the fluid coexisting with the melt. The expelled materials could have been the sources of scheelite–magnetite–chalcopyrite–bearing aplitic veins and copper mineralization of the Yamaguchi Cu‐W skarn deposit.     

川西阿坝州壤古温泉成因机制研究：来自水文地球化学和地球物理勘探的证据

地热资源是一种清洁低碳、储量丰富、安全优质的可再生能源,大力开发利用地热资源,对落实“碳达峰、碳中和”战略目标具有重要意义。壤古温泉位于青藏高原东南缘川西阿坝州壤塘县,为松潘-甘孜褶皱带地热资源空白区钻获的优质地热资源,井口水温39.5℃,自流流量1500 m³/d,属富含偏硅酸、偏硼酸、锶的氟、锂优质热矿水,具有极高的医疗价值。文章以壤古温泉为研究对象,通过水文地球化学、地球物理特征研究,探讨了地热形成机制。结果表明：壤古温泉pH值6.7～7.1,溶解性总固体2050~2760 mg/L,水化学类型为HCO₃-Na型,水岩作用强烈。其氢氧同位素分布于全球大气降水方程线附近,说明热水主要为大气降水补给。Na-K-Mg平衡图表现为未成熟水,表明热水受裂隙潜水或地表冷水强烈混合作用。基于传统地热温标、硅焓混合模型、Cl⁻校正估算热储温度为138~183.3℃,冷水混合比例为77.9~84.3%。综合地球物理勘探、钻探揭露特征,本文构建了壤古温泉成因概念模型,可为壤古温泉的开发利用提供理论支撑。

     

大洋锰结核(壳)中南极底流活动的矿物学与地球化学记录

总结了大洋锰结核(壳)的形态、构造、矿物组合、元素富集特点,以及区域分布和南极底流活动的关系,采用ICP-MS测试手段对中太平洋海山区17个锰结壳样品和1个基岩样品的稀土元素进行测试,结果表明,富钴结壳的REE含量很高,平均为1716.66×10-6,轻稀土明显富集,LREE/HREE平均为4.82,锰结壳样品中除MID06样品有轻微的Ce负异常外,其余样品均具明显的Ce正异常,基岩MKD01呈明显的Ce负异常。不同区域锰结核(壳)中稀土元素的对比研究表明,南极底流活动区和非活动区Ce/La值有显著差异,但不能通过Ce/La值确定底流的迁移路径。这一成果将有助于全面认识大洋成矿作用与海洋环境变迁的内在联系。     

新疆塔什库尔干县曲曼地热田地下热水同位素研究

新疆塔什库尔干县曲曼地热田位于帕米尔高原中东部的塔什库尔干谷地北段,钻孔揭露最高温度162℃。文章测定了曲曼地热田地下热水和地表水样品中的氢、氧、硫、氦等同位素,结合B、Br、Cl等地热地球化学特征,对地热田的补给来源、补给区高程和气温、热源、循环特征等进行了分析。测试结果显示:地下热水中δ¹⁸O为–8.00‰～–10.77‰, δD为–72.50‰～–82.12‰, δ³⁴SCDT为21.10‰～23.76‰;其他水体中δ¹⁸O为–10.50‰～–13.03‰,δD为–81.68‰～–93.87‰,δ³⁴SCDT为1.16‰～7.05‰; ⁴He值为0.01×10^–4,³He/⁴He为0.397 Ra;地下热水中B含量为2.6～13.1 mg/L。对数据进行分析后得到以下结论:(1)曲曼地热田δD-δ¹⁸O分布在大气降水线下方且具有向右上方延伸的特点, TDS值为1～4 g/L, r Na...     

北京市延庆地热田成因模式

通过对地热流体水化学、同位素以及热储岩石热物性测试,分析了延庆地热田大地热流特征、地热流体补给来源、年龄、循环深度以及热储温度等,从源、通、储和盖四方面系统总结了地热田成因。结果显示:延庆地热田属于由正常大地热流加热的非火山型地热系统,热田内大地热流值为75.6m W/m~2,地热流体补给来源于延庆西北部山区的大气降水。热田内三个主要热储中的地热流体年龄和循环深度存在一定区别。燕山期花岗岩、白垩系砂岩和蓟县系白云岩热储中地热水年龄分别为15～21ka、28ka、48ka。花岗岩和砂岩热储中地热流体循环深度约2500m。白云岩热储中流体循环深度为2900～3600m,热储温度分布范围为80.5～98.3℃,平均热储温度90.6℃。     

河南塔山萤石矿地球化学特征及成矿年龄

为探究河南塔山萤石矿的成矿流体、成矿温度、成矿年龄及矿床成因,对研究区稀土元素、流体包裹体和Sm-Nd同位素特征进行了研究。研究区经历多期次的成矿作用,紫色萤石形成时间较早,紫色萤石成矿早期成矿流体中的稀土元素由吸附状态逐渐过渡到络合物状态,成矿晚期成矿流体中的稀土元素主要以络合物形式存在,为主成矿阶段,其球粒陨石标准化稀土元素配分模式和Y/Ho值与牛心山黑云母二长花岗岩、大理岩基本一致,指示三者之间有一定的成因联系。浅绿色萤石形成时间相对较晚,其与紫色萤石的稀土元素配分模式差异较大,表明二者具有不同成矿物质来源。塔山萤石矿发育气液两相包裹体,包裹体均一温度为143.6～168.5℃,盐度(NaCl_eqv)为7.02%～10.43%,密度为0.95～1.01 g/cm³;包裹体气-液相成分以H₂O为主,含有少量C₂H₆,成矿流体属于低温、中低盐度、低密度的NaCl-H₂O体系。测得的浅绿色萤石的成矿年龄为(141±13)Ma,为研究区萤石成矿年龄上限,推断...     

贵州修文小山坝铝土矿中稀土元素地球化学特征

前人已经积累了大量贵州铝土矿的研究成果,但关于铝土矿与其中稀土元素的关系至今不清。本研究以修文小山坝铝土矿为例,通过ICP-MS分析测试,研究了矿石和围岩的稀土元素组成。结果表明,矿石中稀土配分模式为轻稀土富集向右倾斜型,具明显Eu负异常,与下寒武统娄山关群含泥质白云岩稀土特征参数和配分模式相似,指出该矿床成矿物质来源以下寒武统娄山关群含泥质白云岩为主,在相对氧化环境下经风化作用成矿。矿床中稀土元素主要富集于矿体及其周围,与Al2O3含量具正相关关系。矿石中稀土元素含量大多达到或超过综合利用标准,具有巨大的潜在经济价值。