LA-ICP-MS analysis of single fluid inclusions in a quartz crystal (Madan ore district,Bulgaria)

A “long-living” crystal of barren quartz from Kroushev Dol Pb-Zn deposit (Madan district, Rhodope Mountains, Bulgaria) was studied. The semitransparent base part (the “root”) of the crystal contains abundant inclusions, predominantly along healed cracks, while the upper half or third of the crystal is clear and poor in inclusions. In order to analyze fluid inclusions in the quartz crystal, it was cut into 4 pieces across and along the c-axis and doubly-polished sections were prepared. Fluid inclusions trapped in this quartz supply information about the temporal evolution of paleofluids depositing ore minerals.     

华北地块东南缘中生代侵入杂岩中所含榴辉岩类包体矿物微量元素地球化学特征及其意义

华北地块东南缘中生代侵入杂岩中所含榴辉岩类包体中矿物的分析结果表明, 组成榴辉岩类包体的各矿物之间元素的分配在榴辉岩相变质阶段已经达到了化学平衡;石榴石中Al、Fe、Mn, 单斜辉石中Na、Mg、Ca, 角闪石中Na、Mg、Fe等主量元素含量与其全岩之间均呈良好的正相关, 受全岩成分制约;石榴石明显富集HREE、贫LREE, 单斜辉石相对富集LREE、MREE、贫HREE, 两者轻、重稀土含量呈相互消长的互补关系, 石榴石和单斜辉石中分别富集Y、Sr, Ga和过渡族元素Sc、Ti、V、Cr、Co等含量较高, 其含量受全岩成分控制;金红石中稀土元素的含量很少, Fe、Al、Mg、Ca、Mn、Nb、Ta、Cr和Zr含量相对较高, Rb、Sr、Ba含量极低, 部分微量元素(如Nb、Cr、Fe、V、W等)含量与其原岩有继承和对应关系;部分原生或/和退变角闪石的REE配分模式分别与单斜辉石和石榴石相似, 过渡族金属元素等的含量与石榴石、单斜辉石和全岩具有一定的相关性, 角闪石容纳Na、K、Sr、Rb、Ba等元素的能力较强, 其成分除受全岩成分的制约外, 石榴石、单斜辉石对其形成也有影响。榴辉岩类包体与其寄主中生代侵入杂岩中部分高价态/高场强元素(HFSE)和重稀土元素(HREE)呈相互消长的关系。榴辉岩的形成与扬子地块和华北地块之间的俯冲-碰撞作用有关。     

阿尔泰南缘克兰盆地的脉状金-铜矿化及其流体演化

阿尔泰山南缘泥盆纪克兰火山-沉积盆地蕴藏有丰富的VMS锌铅铜多金属矿床。自晚泥盆世至早二叠世末, 阿尔泰山南缘为NE-SW向强烈挤压的构造环境, VMS矿石受到变形变质改造,脉状金铜矿化发育。金(铜)石英脉主要有2种产状:(1)白色-灰白色(硫化物)顺层石英脉(QI), 产于韧脆性剪切带发育地段,呈细脉状或透镜状产于绿泥片岩、黑云片岩中;(2)斜切黄铁矿化蚀变岩、层状铅锌矿和变质岩产状的黄铜矿-黄铁矿石英脉(QII),与晚期的脆性构造有关。金(铜)石英脉的流体包裹体发育,按室温下相态特征有3类。第I类为含子矿物的高盐度包裹体(L-V-S型),子晶为NaCl, 有时为KCl,包裹体呈孤立或无序分布,代表变质早期流体特征。一般NaCl子晶先消失(210~357℃),包裹体的最终均一温度369~512℃,其捕获温度与变质相的相平衡计算温度相当,反映了变质早期中高温热液活动的特征。第II类是富CO₂ 包裹体,包括单相的碳质流体包裹体(L _CO2、L _CO2-CH4或L _CO2-N2)和两相富CO₂包裹体(L _CO2-L _H2O)2个亚类。碳质流体包裹体是常见类型,有时与L _CO2-L_H2O型伴生,在较晚期的黄铜矿-黄铁矿石英脉中表现为原生特征,而在较早的石英脉中常表现为次生特征。萨热阔布的碳质流体可分为纯CO₂包裹体和CO₂-CH₄体系包裹体,纯CO₂包裹体的固体CO₂熔化温度(T_m,CO2)为 -60~-56.5℃,CO₂部分均一温度(T_h,CO2) 变化于-23~+31℃;密度一般为0.85~0.89g·m^-3。CO₂-CH₄包裹体的T_m,CO2＜-57℃,可低达-78.1℃,T_h,CO2低达-33.7~-17.7℃, 其密度高达1.01~1.07g·m^-3。VMS矿床中晚期叠加的黄铜矿石英脉中碳质流体包裹体可分为贫CH₄-N₂和富CH₄-N₂的CO₂-CH₄-N₂包裹体,贫CH₄-N₂的碳质包裹体T_m,CO2=-63.3~-57℃,T_h,CO2=-27.5~+29.7℃;富CH₄-N₂的CO₂-CH₄-N₂包裹体T_m,CO2=-83.4~-65.5℃,T_h,CO2=-56.0~+16.9℃。铜金石英脉中与碳质流体共生的L_CO2-L_H2O型包裹体均一温度T_h,total=205~370℃,略低于第I类高盐度包裹体的T_h,total=369~512℃。据CO₂流体高温高压相图估算包裹体的捕获压力至少为110~300MPa。金(铜)石英脉的主体在相当于445~566℃的高温条件下形成的,而金铜矿化则是在高于205~370℃、110~330MPa的中高温中深条件下发生的。流体包裹体的δ¹⁸O为7.54‰~11.84‰ (QI)和3.82‰~7.82‰ (QII), δD为-84.7‰~-98.2‰(QI)和-75.8‰~-108.8‰ (QII)。结合地质特征和流体研究,说明成矿热液来源与区域变质及相关的岩浆活动有关。     

遵义黄家湾Ni-Mo多金属矿床成矿流体特征:来自方解石流体包裹体、REE和C、O同位素证据

黄家湾矿床是近几年在贵州遵义地区寒武系底部黑色页岩中新发现的以Ni-Mo为主的多元素矿床,本文首次对该矿床成矿阶段方解石的流体包裹体、REE和C、O同位素组成特征进行了系统研究.研究结果显示:(1)该矿床成矿阶段方解石中含有3种类型的流体包裹体:富液相气液两相水溶液包裹体;富气相气液两相水溶液包裹体;纯液相包裹体.它们的气相分数变化较大,显示成矿过程中可能发生过沸腾作用.流体包裹体的显微测温结果显示,成矿流体的冰点温度为-11.6～-5.5℃,流体盐度变化范围为8.55％ ～ 15.57％ NaCleqv,均一温度为109.0 ～ 181.8℃,对应流体密度为0.97 ～ 1.44g·cm-3;(2)遵义黄家湾钼-镍多金属矿床中与成矿期有关的方解石的稀土总量高且变化范围宽(39.9×10-6～ 275×10-6),配分曲线为轻稀土富集((La/Yb)N=29.6 ～63.3)的右倾型,且铕正异常明显(Eu/Eu*为2.14～14.8),与现代海底热液矿床中方解石的稀土特征类似;(3)同位素测定显示成矿流体的碳氧同位素组成分别为δ13C V-PDB=-6.3‰～-5.7‰,δ18OV-SMOW=15.6‰ ～16.0‰,计算得到流体水的δ18OV-SMOW-H2O‰平均值变化于-0.97‰～ +5.16‰之间.上述综合研究表明:黄家湾Ni-Mo多金属矿床成矿流体主要为海水和地层中的建造水(盆地热卤水),同时由海水演化来的海底热液也参与了成矿过程.成矿流体中的碳可能由深源碳与海相碳酸盐岩共同提供.     

Intracellular mineral grains in the xenophyophore Nazareammina tenera (Rhizaria, Foraminifera) from the Nazaré Canyon (Portuguese margin, NE Atlantic)

Xenophyophores, a group of large agglutinated foraminifera, are characterized by the presence of numerous intracellular barite grains, termed granellae, the function and origin of which is unclear. The recently described xenophyophore Nazareammina tenera (Gooday et al., in press), from abyssal depth (4300 m) in the Nazaré Canyon contains an unusually dense concentration of mineral grains in its cytoplasm. Uniquely among known xenophyophores, the intracellular grains in this species comprise a variety of different mineral types in addition to barite. They exhibit a wide range of morphologies and energy dispersive X-ray analysis indicated that they include Ti-bearing minerals, many of them rod-shaped (probably rutile), as well as those containing Fe and Ti (possibly ilmenite and anatase), and Al and Si (probably clay minerals). While the function of intracellular particles in xenophyophores remains unclear, the presence of numerous particles of various types in the cytoplasm suggests that they originate from the sediment. This suite of intracellular mineral grains is completely different from that used to construct the agglutinated test of N. tenera, suggesting that this species is able to discriminate between different kinds of particles. A second xenophyophore species, Reticulammina cerebreformis (Gooday et al., in press), which is abundant at the same site as N. tenera, is devoid of intracellular particles, suggesting that their presence in N. tenera is a species-specific characteristic.     

Grains Containing Oil Inclusions in Different Hydrocarbon Production and Show Types of Sandstone Reservoirs from the Central Junggar Basin, Northwest China

The values of grains containing oil inclusions (GOI) in 120 reservoir sandstone samples from the central Junggar Basin of Northwest China were investigated. The sandstones are characterized by different types of hydrocarbon production and shows. The values range from 0.015% to 19.9%, and show a fairly good correlation with the hydrocarbon production/shows, which are qualitatively suggestive of reservoir hydrocarbon abundance and petroleum migration. Thus, it may be implied that the values can reflect hydrocarbon migration, being not controlled mainly by the other influencing factors. Further correlation between the values and the reservoir hydrocarbon production and show types indicates that the GOI method can be used in hydrocarbon migration study when the petroleum type of a reservoir is normal oil or gas alone, but it should be used with caution when light oil charges the reservoirs or a complex hydrocarbon migration event takes place. The case study in the central Junggar Basin using the method presents some new understanding on hydrocarbon migration. Thus, the method may help to solve specific petroleum geological problems, and can be treated as a routine tool in hydrocarbon migration study.     

甘肃肃北县鹰嘴山金矿矿质来源分析及成矿模式探讨

通过对鹰嘴山金矿容矿围岩的研究及加里东期超基性岩含金性的评价,认为鹰嘴山金矿的金主要来自超基性岩,而且超基性岩浆的侵入为黒茨沟组火山岩中微量金的加剧活化提供了热力条件。同时研究了断裂控矿性质、矿床地球化学特征认为,鹰嘴山金矿是一个与超基性有关的中低温热液型金矿床,提出了成矿模式。     

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...     

松辽盆地钱家店砂岩型铀矿床油气运移与铀成矿的关系:来自流体包裹体的证据

为探究油气运移与铀成矿的关系,笔者以松辽盆地钱家店砂岩型铀矿床为研究对象,系统开展了含矿砂岩薄片鉴定、电子探针研究以及流体包裹体岩相学和显微测温研究.结果表明:①研究区强矿化段砂岩硅质胶结物含量较多,为隐晶质玉髓胶结物;成岩演化序列为,泥晶方解石、自生黏土膜,石英加大边、石英加大边外围黏土膜、颗粒间压实的隐晶质玉髓胶结...