辽宁鞍山－本溪地区铁矿床流体包裹体和硫、氢、氧同位素特征研究

鞍山-本溪地区是我国最大的铁矿集区,分布有诸多大型、特大型铁矿床,并且产出有弓长岭二矿区大型和齐大山、南芬中型磁铁富矿床。贫铁矿体与变质沉积岩和火山碎屑岩等围岩呈层状或似层状产于太古宙花岗岩中,富铁矿体(TFe50%)呈层状或透镜体状产于贫铁矿体和围岩及其附近的断裂带中,并可见明显的热液蚀变现象。为了探讨鞍本地区富铁矿的成因,为指导找富矿提供依据,本文主要对比研究了鞍本地区贫铁矿石和富铁矿石中流体包裹体、硫同位素和氢氧同位素特征。贫铁矿石(磁铁石英岩和假象赤铁石英岩)石英中含有大量的孤立分布负晶形气体包裹体(Ⅰc类包裹体),富铁矿石石英中主要以液体包裹体(Ⅰb类包裹体)为主,可见含子矿物的流体包裹体;贫铁矿石中黄铁矿的δ34S变化范围为-6.5‰~11.8‰,平均值为0.4‰,富铁矿石中黄铁矿的δ34S变化范围较大,为-7‰~14.4‰,平均值为2.0‰;贫铁矿石中磁铁矿δ18 O变化范围为3.4‰~10.4‰,平均值为7.1‰,石英δ18 O变化范围为11.8‰~15.1‰,平均值为13.4‰,富铁矿石中磁铁矿δ18 O变化范围为-1.4‰~6.5‰,平均值为2.3‰,富铁矿石中石英δ18 O变化范围为9.6‰~15.8‰,平均值为13.6‰,δD变化范围为-129‰~-75‰,平均值为-104‰。富铁矿石中石英流体包裹体、黄铁矿δ34S和磁铁矿δ18 O部分继承了贫铁矿石的特征,但是显示更多的后期热液特征,暗示鞍本地区富铁矿石是在贫铁矿石的基础上受后期热液改造形成的。富铁矿石中石英的氢氧同位素特征表明其热液流体主要为混合岩化热液,富铁矿的形成可能为去硅富铁模式,同时也可能有铁质活化再转移模式。     

Microbial Processes in Stratified Lake Doroninskoe(Transbaikal Region)

正In recent decades,meromictic ponds attract the attention of researchers in different directions,because here the character of the physical,chemical and biological processes differ from those of typical mixing waters(Kuznetsov,1970;Hutchinson,1969).In Transbaikalia widely distributed soda and salt lakes with different salinity.Notable among them is Lake Doroninskoye,which has a pronounced stratification for a     

基于语料库的中国大学生动/名词搭配研究

采用中国学习者语料库（CLEC）和本族语语料库（Brown和LOB语料库）中的真实语料，对中国大学生的动词／名词搭配使用行为进行研究。针对同一名词或动词的搭配词，中国学习者的搭配词与本族语者的搭配词差异极大，甚至有些搭配词在本族语者的语料中从未出现过。进一步分析表明，中国学习者的搭配词选择很大程度受到该词在母语（汉语）中搭配词的影响。     

西藏洞嘎金矿床地质特征、原位硫同位素组成及成因探讨

洞嘎金矿位于西藏雄村矿集区, 是冈底斯成矿带较早发现且投入开采的金矿, 但研究程度低, 矿床成因存在较大争议。本文通过系统的矿床地质特征研究, 开展了硫化物原位硫同位素测试, 分析成矿物质来源, 进而探讨洞嘎金矿的成因。洞嘎金矿体受控于雄村组凝灰岩中的裂隙系统, 矿体呈脉状产出, 已探获金金属资源量9.55 t, 达到中型规模。矿石构造主要为脉状-细脉状构造, 金主要以包裹金和粒间金的形式赋存于黄铁矿和黄铜矿中。根据脉体穿插关系及矿物共生组合特征, 将洞嘎金矿的成矿过程划分为热液成矿期与表生氧化期, 其中热液成矿期为主成矿期, 可进一步划分为3个成矿阶段: 成矿早阶段、成矿主阶段及成矿晚阶段。洞嘎金矿床硫化物的硫同位素δ34S= –1.57‰~+5.26‰, 平均值+1.69‰, 具明显的塔式分布, 表明硫源具岩浆硫的特点。结合前人已发表的数据, 我们认为洞嘎金矿属于斑岩铜金成矿系统外围的热液脉型金矿床, 深部可能存在斑岩型铜金矿床, 找矿潜力极大。洞嘎金矿的成矿物质来源主要为地幔, 有少量的地壳物质(俯冲沉积物)加入。洞嘎金矿床的金与绿泥石密切相关, 该绿泥石主要为溶蚀-迁移-结晶机制形成, 绿泥石形成过程导致含金热液流体成分及物理化学性质发生改变, 使得成矿流体中的金发生卸载, 最终在凝灰岩的裂隙系统中形成洞嘎金矿床。     

内蒙古沙章土锡铜多金属矿床成矿年代学及成因探讨

沙章土锡铜多金属矿位于内蒙古中部,近年来区内锡矿找矿工作的新发现,锡矿体为呈脉状、浸染状分布的电气石脉、电英岩及电英岩化蚀变岩,含锡矿物主要为锡石;铜矿体为浸染状分布的黄铜矿化电英岩化蚀变岩、方铅矿-闪锌矿-黄铜矿化蚀变岩,含铜矿物主要为黄铜矿,同时,经由钻探工程在矿床深部发现有闪长玢岩岩体。为了查清锡铜矿体成矿年龄及成矿物质来源,明确矿床成因类型,进一步指导找矿工作,文章在野外调查和室内综合研究基础上,对锡石开展了LA-MC-ICP-MS U-Pb定年及电子探针分析工作,并对共生的硫化物进行了硫同位素测试。测试结果显示,锡石成矿年龄为(316.3±8.9)Ma,为海西期晚石炭世阶段的产物;探针数据显示其成因为热液型锡石;硫同位素测试结果,δ³⁴S值为0.43‰～7.34‰,平均值4.39‰,具混合硫源特征。综上所述,笔者初步认为沙章土锡铜矿床的成因类型是与闪长玢岩有关的岩浆热液型。     

Metallogenic age and fluid evolution of the Kangshan Au-polymetallic deposit in the southern margin of the North China Craton: Constraints from monazite U-Pb age,and in-situ trace elements and S isotopes of pyriteSCIEI北大核心CSCD

小秦岭-熊耳山金矿集区位于华北克拉通南缘,发育众多伴生铅锌银等金属的金矿,成为揭示克拉通破坏型金矿成因的天然实验室。产于小秦岭-熊耳山金矿集区内的康山金多金属矿床受控于北东向的中生代脆性断裂,赋存于新太古代变质岩和中元古代火山岩中。成矿过程可分为4个热液阶段:石英±黄铁矿阶段、石英-黄铁矿-黄铜矿-自然金阶段、多金属硫化物-自然金-石英-铁白云石阶段、石英-方解石±萤石阶段。本文获得康山金多金属矿床金成矿阶段热液独居石LA-ICP-MS U-Pb年龄为131.7±4.6Ma,与晚中生代华北克拉通破坏有关的岩浆热液成矿作用时代一致。本次研究开展的各阶段黄铁矿原位微量元素单点和扫面分析,发现第2阶段Au与Co、Ni、As呈正相关关系,且有明显的振荡环带,Cu、Ag、Sb、Pb、Bi这几种元素从黄铁矿颗粒的核部向边缘含量逐渐降低,且黄铁矿颗粒中出现富含这些元素的矿物包裹体,说明该阶段发生流体沸腾作用;而第3阶段黄铁矿中各微量元素含量为所有阶段中最低,黄铁矿无振荡环带且裂隙中有富含各微量元素的硫化物充填,说明各种元素在该阶段均得到充分卸载,且成矿流体的化学性质较稳定。结合前人关于该矿床各阶段流体包裹体分析结果,表明流体沸腾是Au的主要沉淀机制,而流体混合是Pb、Zn、Ag的主要沉淀机制。黄铁矿中微量元素含量指示,从第1阶段到第3阶段流体温度依次降低;第2和第3阶段流体fO2比第1阶段高且后两者相差不大。根据黄铁矿Co、Ni含量及比值的计算,认为第1和第2阶段黄铁矿为岩浆热液成因,第3阶段黄铁矿受围岩物质影响。黄铁矿原位S同位素分析得到第1至第3阶段黄铁矿δ34S分别为+6.6‰-+8.9‰、+5.0‰-+7.2‰和+6.0‰-+8.7‰,均与区域花岗岩类的S同位素值类似。综上所述,本文得出康山金多金属矿床形成于早白垩世与华北克拉通破坏有关的岩浆热液成矿作用。     

滇东南都龙Sn-Zn多金属矿床交生硫化物微区主量元素、硫同位素特征及成因研究

都龙Sn-Zn多金属矿床位于滇东南老君山锡锌钨多金属成矿区南部,是中国3大锡石硫化物矿床之一。该矿床发育闪锌矿-黄铜矿-磁黄铁矿密切共生结构,即硫化物交生结构。文章利用电子探针和LA-MC-ICP-MS对具有交生结构的闪锌矿-黄铜矿-磁黄铁矿和毒砂进行了微区主量元素和硫同位素测试,以期明确其成因及硫的来源。主量元素测试结果显示,闪锌矿中的w(Zn)为52.23%~57.22%,w(S)为33.06%~36.10%,w(Fe)为9.92%~12.24%,w(Cu)为0.11%~0.30%;黄铜矿中的w(Cu)为33.95%~35.08%,w(S)为33.49%~35.27%,w(Fe)为30.74%~31.41%,w(Zn)为0.04%~1.50%;磁黄铁矿中的w(Fe)为49.30%~51.94%,w(S)为38.36%~39.69%,w(Zn)为9.35%~11.01%,w(Cu)为0.05%~0.15%。磁黄铁矿和黄铜矿包裹体边部和核部成分均一,且投影点全部落在固溶体出溶区域,说明都龙矿床交生闪锌矿-黄铜矿-磁黄铁矿是固溶体分离成因。原位S同位素分析结果显示,闪锌矿的δ³⁴S为0.9‰~3.2‰,磁黄铁矿的δ³⁴S为0.6‰~2.1‰,毒砂的δ³⁴S为2.9‰~4.2‰,黄铜矿的δ³⁴S为0.6‰~2.8‰,均显示为岩浆来源特征。主量元素温度计估算的闪锌矿-黄铜矿的形成温度介于285~394℃,指示该矿床主要硫化物形成于中高温阶段。     

Origin and quantitative source assessment of deep oils in the Tazhong Uplift,Tarim Basin

A large amount of deep oil has been discovered in the Tazhong Uplift, Tarim Basin whereas the oil source is still controversial. An integrated geochemical approach was utilized to unravel the characteristics, origin and alteration of the deep oils. This study showed that the Lower Cambrian oil from well ZS1C (

_1x) was featured by small or trace amounts of biomarkers, unusually high concentration of dibenzothiophenes (DBTs), high δ³⁴S of DBTs and high δ¹³C value of n-alkanes. These suggest a close genetic relationship with the Cambrian source rocks and TSR alteration. On the contrary, the Middle Cambrian oils from well ZS1 (

_2a) were characterized by low δ¹³C of n-alkanes and relatively high δ³⁴S of individual sulfur compounds and a general “V” shape of steranes, indicating a good genetic affinity with the Middle–Upper Ordovician source rocks. The middle Cambrian salt rock separating the oils was suggested to be one of the factors responsible for the differentiation. It was suggested that most of the deep oils in the Tazhong Uplift were mixed source based on biomarkers and carbon isotope, which contain TSR altered oil in varied degree. The percentage of the oils contributed by the Cambrian–Lower Ordovician was in the range of 19–100% (average 57%) controlled by several geological and geochemical events. Significant variations in the δ³⁴S values for individual compounds in the oils were observed suggesting a combination of different extent of TSR and thermal maturation alterations. The unusually high DBTs concentrations in the Tazhong-4 oilfield suggested as a result of mixing with the ZS1C oil (

_1x) and Lower Ordovician oils based on δ³⁴S values of DBT. This study will enhance our understanding of both deep and shallow oil sources in the Tazhong Uplift and clarify the formation mechanisms of the unusually high DBTs oils in the region.     

Solubility of Anhydrite, CaSO4, in NaCl-H2O Solutions at High Pressures and Temperatures: Applications to Fluid-Rock Interaction

Anhydrite solubility in H₂O–NaCl solutions was measuredat 6–14 kbar, 600–800°C and NaCl mole fractions(X_NaCl) of 0–0·3 in piston–cylinder apparatus.Solubilities were determined by weight changes of natural anhydritein perforated Pt envelopes confined with fluid in larger Ptcapsules. In initially pure H₂O at 10 kbar and 800°C, CaSO₄concentration is low (0·03 molal), though much largerthan at the same temperature and 1 kbar. Hematite-buffered experimentsshowed slightly lower solubilities than unbuffered runs. CaSO₄solubility increases enormously with NaCl activity: at 800°Cand 10 kbar and X_NaCl of 0·3, CaSO₄ molality is 200 timeshigher than with pure H₂O. Whereas CaSO₄ solubility in pureH₂O decreases with rising T at low T and P, the high-P resultsshow that anhydrite solubility increases with T at constantP at all X_NaCl investigated. The effects of salinity and temperatureare so great at 10 kbar that critical mixing between sulfate-richhydrosaline melts and aqueous salt solutions is probable at900°C at X_NaCl 0·3. Recent experimental evidencethat volatile-laden magmas crystallizing in the deep crust mayevolve concentrated salt solutions could, in light of the presentwork, have important implications regarding such diverse processesas Mount Pinatubo-type S-rich volcanism, high-f O₂ regionalmetamorphism, and emplacement of porphyry Cu–Mo ore bodies,where anhydrite–hematite alteration and fluid inclusionsreveal the action of very oxidized saline solutions rich insulfur. KEY WORDS: anhydrite; sulfur; solubility; metamorphic brines; granulites     

On the Retrieval of Volcanic Sulfur Dioxide Emissions from GOME Backscatter Measurements

We focus on the retrieval of volcanic sulfur dioxide (SO₂) emissions from an analysis of atmospheric UV backscatter spectra obtained by the Global Ozone Monitoring Experiment (GOME) spectrometer on board the ESA European Remote Sensing Satellite (ERS-2). Here, the last major eruptions of Mt. Etna on Sicily (Italy) in July/August 2001 and October/November 2002 provided an excellent opportunity to study the retrieval of SO₂ columnar amounts from ground-based, LIDAR and satellite measurements. Our study shows that the bulk of emitted SO₂ was confined in the troposphere, mainly between 700 hPa and 400 hPa which is confirmed by trajectory analysis, by LIDAR observations and AVHRR observations. The area of influence of Mt. Etna eruptions ranges from the Western Saharan Desert to Greece and the near east states and even down to the basin of Tschad, Africa. Our analysis revealed that information about the plume height of volcanic eruptions and aerosol parameters is necessary for a reliable quantitative retrieval of SO₂ from space-borne sensor data at periods perturbed by volcanic eruptions.