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西准白杨河铍矿床萤石及流体包裹体特征 总被引：3，自引：0，他引：3
利用激光测温学和激光拉曼光谱方法,通过镜下观察,研究了白杨河铍矿床与铍成矿作用有关的脉石矿物(萤石),将萤石分为4个期次,其中第三期萤石与铍成矿关系最密切。萤石流体包裹体具低盐(0.7%~7.0%)、低温(89.7℃~188.9℃)的特征,第三期萤石脉流体包裹体成矿温度99.4℃~120.5℃,成矿盐度3.5%~5.4%,与铍矿物属同一期,揭示出该矿床成矿流体为低温、低盐度热液。 相似文献
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德兴斑岩铜矿成矿过程的氧、锶、钕同位素证据 总被引：10，自引：0，他引：10
为探讨德兴铜厂斑岩铜矿床成矿热液流体的来源、作用范围、时空演化及Cu在热液流体中的行为和迁移方向等重要问题，对采集于该矿床南部不同蚀变程度的岩石进行了氧、锶、钕同位素分析，结果表明，虽然与铜三斑岩铜矿成矿过程有关的热液流体至少有3种，包括高温岩浆流体、来自深部围岩的非岩浆流体和大气降水，但是起主导作用的是岩浆流体，钕、锶同位素在空间上的变化表明，在成矿流体形成及演化过程中，锶同位素值由斑岩体内部向围岩接触带有规律地升高（0.705→0.711），指示了矿床是因热液流体将成矿元素从岩体内部迁移到接触带附近富集而成的，它符合斑岩铜矿的正岩浆模式，而钕同位素则相对稳定，可作为蚀变侵入体岩浆起源的示踪剂。 相似文献
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与高硅富氟火成岩(流纹岩或花岗斑岩)有关的铍矿床中常伴有铀矿化,其成矿特色明显,是认识岩浆-岩浆热液-热液演化过程中铍与铀地球化学行为异同的理想对象,但其中铍与铀成矿的时空关系及成因关系尚不清楚。为了理解该类矿床中铍与铀的成生关系,并为区域内铍与铀的找矿勘查提供理论支撑,本文选取该类矿床的典型代表—西准噶尔白杨河铍铀矿床为研究对象,通过镜下观察、扫描电镜能谱和激光拉曼光谱分析,对矿区内单铍矿石、单铀矿石和铍铀矿石开展了系统的岩相和矿相学研究。结果显示,与铍矿化相关的围岩蚀变为钠长石化、电气石化、白云母化、萤石化、碳酸盐化和绿泥石化,与铀矿化相关的围岩蚀变为硅化、赤铁矿化、萤石化、伊利石化和锰矿化(含少量铅),且铍铀矿石中可见沥青铀矿切穿羟硅铍石的现象。结合铍与铀的地球化学行为和前人研究成果,认为白杨河铍铀矿床中铍矿化与铀矿化应是不同期热液作用的结果:铍矿化可能是花岗斑岩深部岩浆房分异的岩浆热液在不断演化过程中形成的,而铀矿化可能与后期流体(如幔源流体、加热循环的大气降水等)的淋滤作用有关。 相似文献
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661铀矿床流体包裹体特征及成矿流体来源探讨 总被引：2，自引：0，他引：2
本文利用显微测温学和激光喇曼光谱方法,研究了661铀矿床与铀成矿作用有关的脉石矿物(萤石、石英和方解石)中的流体包裹体。结果表明,成矿早期脉石矿物中的流体包裹体均一温度为130~250℃,盐度为1.65%~3.44%(NaCl),密度为0.81~1.01 g/cm3;成矿晚期流体包裹体的均一温度为95~150℃,盐度为1.48%~1.64%(NaCl),密度为0.88~0.96g/cm3。这些资料揭示出该矿床的成矿流体为中低温、低盐度、中等密度热液。激光喇曼光谱气相成分分析主要为H2O,未见其他气体成分。明显不同于岩浆热液矿床中的包裹体特征及其成矿流体的性质,结合该矿床成矿地质特征、氧同位素及区域铀矿床成矿物化条件等资料,进一步分析推断成矿流体的水可能主要来自大气降水。 相似文献
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赣南黄泥湖铀矿床成矿流体的氦、氩同位素组成及其意义 总被引：1，自引：0，他引：1
黄泥湖铀矿床是赣南典型的热液铀矿床,文章通过对该矿床成矿期形成的萤石、方解石和黄铁矿中流体包裹体的He、Ar同位素的测定表明,黄泥湖铀矿床流体包裹体中3 He/4 He值为0.007~2.272Ra(绝大部分在0.024~1.754Ra),40 Ar/36 Ar值为191.6~1126.1(绝大部分高于295.5),认为成矿流体的氦具有壳-幔混合来源特征,其中幔源流体占主导地位,地壳流体端元为含有一定放射性成因Ar的大气降水。结合前人研究成果,认为黄泥湖铀矿床为深源热液成因,与晚燕山期华南岩石圈伸展作用有关。 相似文献
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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. 相似文献
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白石坡银矿床是大别山地区具代表性的中型银矿床,已探明银储量219.8 t。银矿体与矿区花岗斑岩空间关系密切。为深化理解其成矿地质背景,对白石坡花岗斑岩进行了详细的岩相学观察、锆石U-Pb同位素测年、岩石地球化学和Sr-Nd-Hf同位素研究。通过激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)分析,获得花岗斑岩锆石U-Pb同位素年龄为(142±2) Ma(MSDW=1.9),表明其形成于早白垩世。岩石具较高的SiO2含量(73.94%~76.14%)和富K2O(7.46%~9.55%)等特点,总体属于强过铝质(A/CNK=1.07~1.45)、高钾钙碱性系列,具高分异花岗岩特征;岩石富集轻稀土((LREE/HREE)N=10.88~12.89),具中等Eu负异常,并具有较低的Sr、Y、Yb含量。岩石锶同位素初始比值ISr为0.714 762~0.715 890,钕同位素εNd(t)值约为-13.8,两阶段Nd模式年龄TDM2=2.06~2.05 Ga。锆石εHf(t)值集中于-16.6~-13.5,两阶段Hf模式年龄TDM2=1.98~1.81 Ga。岩石地球化学和Sr-Nd-Hf同位素特征共同揭示,该花岗斑岩可能是扬子陆壳北缘古老地壳物质重熔演化的产物。白石坡花岗斑岩及相关银矿床形成于白垩纪加厚下地壳拆沉之前地壳持续挤压加厚环境,与陈棚组火山活动不存在直接联系。 相似文献
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Influences of the unsaturated,saturated, and riparian zones on the transport of nitrate near the Merced River,California, USA 总被引：1，自引：0，他引：1
Joseph L. Domagalski Steven P. Phillips E. Randall Bayless Celia Zamora Carol Kendall Richard A. WildmanJr Janet G. Hering 《Hydrogeology Journal》2008,16(4):675-690
Transport and transformation of nitrate was evaluated along a 1-km groundwater transect from an almond orchard to the Merced River, California, USA, within an irrigated agricultural setting. As indicated by measurements of pore-water nitrate and modeling using the root zone water quality model, about 63% of the applied nitrogen was transported through a 6.5-m unsaturated zone. Transport times from recharge locations to the edge of a riparian zone ranged from approximately 6 months to greater than 100 years. This allowed for partial denitrification in horizons having mildly reducing conditions, and essentially no denitrification in horizons with oxidizing conditions. Transport times across a 50–100-m-wide riparian zone of less than a year to over 6 years and more strongly reducing conditions resulted in greater rates of denitrification. Isotopic measurements and concentrations of excess N2 in water were indicative of denitrification with the highest rates below the Merced River. Discharge of water and nitrate into the river was dependent on gradients driven by irrigation or river stage. The results suggest that the assimilative capacity for nitrate of the groundwater system, and particularly the riverbed, is limiting the nitrate load to the Merced River in the study area. 相似文献
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山西五台山区滹沱群变质玄武岩岩石学、地球化学特征及其成因意义 总被引：10，自引：0，他引：10
在野外地质调查的基础上,选取滹沱群豆村亚群底部四集庄组玄武岩、顶部青石村组玄武岩和东冶亚群中下部河边村组玄武岩,进行岩石学和地球化学研究。分析结果表明：玄武岩主量元素高TiO2、TFeO,低MgO,具有演化的基性岩浆的特征。稀土元素含量相对较高,具有弱—中等程度的轻稀土元素富集,中等程度的轻重稀土元素分异,轻微的Eu异常;玄武岩中Cr、Ni含量变化较大,但与Mg#具有很好的正相关性。微量元素配分图解中具有明显的Sr负异常,部分样品具有Nb、Ta和Ti负异常,无Zr、Hf负异常,与岛弧火山岩不同;同时Nb、Ta无分异,Zr/Hf值较高,具有板内玄武岩浆的特征。综合分析认为,滹沱群玄武岩可能形成于板内裂谷环境。在岩浆上升过程中发生橄榄石与尖晶石的分离结晶作用,同时不同程度地受到地壳的混染。 相似文献
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以出露在西藏南木林县秦马弄地区二长花岗岩体为研究对象,从野外地质调查、岩石学、LA-ICP-MS锆石U-Pb定年、元素和Lu-Hf同位素地球化学等方面对其进行了分析研究。结果显示：秦马弄地区二长花岗岩体类似于A型花岗岩,形成于古近纪(E1),其LA-ICP-MS锆石U-Pb年龄为(62.0±0.5)~(63.0±0.5) Ma;岩体形成的温度较高(锆石饱和温度为745~805 ℃,平均766 ℃);岩石富SiO2(72.6%~75.0%)、Na2O(2.86%~3.59%)和K2O(4.12%~5.25%),贫CaO(0.72%~1.39%)和MgO(0.26%~0.36%),高FeOT/MgO值(7.26~10.3),属高钾钙碱性系列,弱过铝质;岩石具明显的负Eu异常(Eu/Eu*=0.40~0.70),普遍表现出Ba、Sr、P、Ti元素的亏损和Rb、Th、K、Zr、Hf元素的富集。εHf(t)值为-4.7~-1.8,其两阶段地壳Hf模式年龄tDM2为(1.1~1.3) Ga。秦马弄A型花岗岩体是冈底斯基底地壳物质部分熔融的岩浆产物,形成于古近纪印度板块与欧亚板块俯冲碰撞引起的总体为岛弧背景下的局部拉张构造环境。 相似文献
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扬子北缘马元铅锌矿床闪锌矿微量元素及S-Pb-He-Ar-C同位素地球化学研究 总被引：7，自引：3，他引：4
马元铅锌矿床是近年扬子陆块北缘铅锌找矿的新突破。矿体呈层状、似层状产于碑坝隆起翼部震旦系灯影组角砾状白云岩层间构造带中,围岩蚀变很弱。矿石中硫化物以闪锌矿、方铅矿为主,中粗粒晶质结构,充填于白云岩角砾间。闪锌矿富集Cd、Ge、Ag,贫In、Tl、Se,Ga/In为6~132,Ge/In多1000,成矿温度以中-低温为主。金属硫化物ε~(34)S值相对集中,为12.9‰~19.4‰,平均为17.4‰,来自于海相硫酸盐的还原。铅同位素组成稳定,~(206)Pb/~(204)Pb为17.858~17.918:~(207)Pb/~(204)Pb为15.603~15.694;~(208)Pb/~(204)Pb为37.756~38.046,具有造山带和上地壳铅的特征,震旦系可能提供了金属成矿物质。闪锌矿中流体包裹体的~3He/~4He为0.03Ra~1.05Ra,~(40)Ar/~(36)Ar为326.1~765.1,~(38)Ar/~(36)Ar为0.183~0.204,表明成矿流体主要为地壳流体和饱和大气水(大气降水或海水)的混合。闪锌矿内流体包裹体挥发分δ~(13)C_(CH_4)值为-36.01‰~-28.80‰,δ~(13)C_(C_2H_6)值为-27.72‰~-22.44‰,δ~(13)C_(CO_2)值为-23.24‰~-9.68‰,表明有机流体参与了成矿作用。石英、方解石的H-O同位素结果表明具有海水和有机水混合的特征。可见,成矿流体具有两种流体混合的特征,一为蒸发海水与围岩反应所形成的盆地卤水,二为有机流体。推测矿区可能存在一个古油气藏,由于TSR生成一高硫气藏,为区内还原性有机流体的主要来源。当富含Pb、Zn等成矿物质的成矿流体运移至富含CH_4和H_2S的还原性流体的矿区角砾岩带时,两种流体混合,Pb、Zn等遇到H_2S发生反应而沉淀成矿,并伴生热液白云石等,形成了马元铅锌矿床。综上所述,我们认为马元矿床属MVT型铅锌矿床。 相似文献
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I. A. Tararin V. M. Chubarov E. K. Ignat’ev S. V. Moskaleva 《Russian Journal of Pacific Geology》2007,1(1):82-97
The geology and mineralogy of host metamorphic rocks, the mineralogy of sulfide ores, and the distribution of PGE mineralization were studied in detail for the Kvinum-1 and Kvinum-2 copper-nickel occurrences of the Kvinum ore field, which are the most promising targets for the copper-nickel-PGE mineralization of the Sredinny Range of Kamchatka. It was established that stringer-disseminated and massive copper-nickel ores are localized in amphibole peridotites, cortlandites, and form ore bodies varying from tens of centimeters to 5–20 m thick among the layered cortlandite-gabbroid massifs. The massive sulfide ores were found only at the bottom of cortlandite bodies and upsection grade into stringer-disseminated and disseminated ores. Pyrrhotite, chalcopyrite, and pentlandite are the major ore minerals with a sharply subordinate amount of pyrite, sphalerite, galena, arsenopyrite, and löllingite. Besides pentlandite, the Ni-bearing minerals include sulforasenides (gersdorffite), arsenides (nickeline), and tellurides (melonite) of nickel. It was found that PGE mineralization represented by antimonides (sudburyite) and tellurobismuthides (michenerite) of Pd with sharply subordinate platinum arsenide (sperrylite) is confined to the apical parts of massive sulfide zones and the transition zone to the stringer-disseminated ores. Ore intervals enriched in arsenides and tellurides of Ni, Pd, and Bi contain high-purity gold. In the central parts of the orebodies, the contents of PGE and native gold are insignificant. It is suggested that the contents of major sulfide minerals and the productivity of PGE mineralization in the cortlandites are defined by combined differentiation and sulfurization of ultramafic derivatives under the effect of fluids, which are accumulated at the crystallization front and cause layering of parental magmas with different sulfur contents. The fluid-assisted layering of mafic-ultramafic massifs resulted in the contrasting distribution of PGM in response to uneven distribution of sulfur (as well as As, Te, and Bi) during liquid immiscibility. The productivity of PGE mineralization significantly increases with increasing contents of S, As, Te, and Bi (elements to which Pt and, especially, Pd have high affinity) in fluids. 相似文献
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A geophysical survey was conducted to determine the depth of the base of the water-table aquifer in the southern part of
Jackson Hole, Wyoming, USA. Audio-magnetotellurics (AMT) measurements at 77 sites in the study area yielded electrical-resistivity
logs of the subsurface, and these were used to infer lithologic changes with depth. A 100–600 ohm-m geoelectric layer, designated
the Jackson aquifer, was used to represent surficial saturated, unconsolidated deposits of Quaternary age. The median depth
of the base of the Jackson aquifer is estimated to be 200 ft (61 m), based on 62 sites that had sufficient resistivity data.
AMT-measured values were kriged to predict the depth to the base of the aquifer throughout the southern part of Jackson Hole.
Contour maps of the kriging predictions indicate that the depth of the base of the Jackson aquifer is shallow in the central
part of the study area near the East and West Gros Ventre Buttes, deeper in the west near the Teton fault system, and shallow
at the southern edge of Jackson Hole. Predicted, contoured depths range from 100 ft (30 m) in the south, near the confluences
of Spring Creek and Flat Creek with the Snake River, to 700 ft (210 m) in the west, near the town of Wilson, Wyoming.
Received, May 1997 · Revised, February 1998 · Accepted, April 1998 相似文献
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E. M. Prasolov S. A. Sergeev B. V. Belyatsky E. S. Bogomolov K. A. Gruzdov I. N. Kapitonov R. Sh. Krymsky V. O. Khalenev 《Geochemistry International》2018,56(1):46-64
This paper reports the first results of a study of 11 isotope systems (3He/4He, 40Ar/36Ar, 34S/32S, 65Cu/63Cu, 62Ni/60Ni, 87Sr/86Sr, 143Nd/144Nd, 206–208Pb/204Pb, Hf–Nd, U–Pb, and Re–Os) in the rocks and ores of the Cu–Ni–PGE deposits of the Norilsk ore district. Almost all the results were obtained at the Center of Isotopic Research of the Karpinskii All-Russia Research Institute of Geology. The use of a number of independent genetic isotopic signatures and comprehensive isotopic knowledge provided a methodic basis for the interpretation of approximately 5000 isotopic analyses of various elements. The presence of materials from two sources, crust and mantle, was detected in the composition of the rocks and ores. The contribution of the crustal source is especially significant in the paleofluids (gas–liquid microinclusions) of the ore-forming medium. Crustal solutions were probably a transport medium during ore formation. Air argon is dominant in the ores, which indicates a connection between the paleofluids and the atmosphere. This suggests intense groundwater circulation during the crystallization of ore minerals. The age of the rocks and ores of the Norilsk deposits was determined. The stage of orebody formation is restricted to a narrow age interval of 250 ± 10 Ma. An isotopic criterion was proposed for the ore-bearing potential of mafic intrusions in the Norilsk–Taimyr region. It includes several interrelated isotopic ratios of various elements: He, Ar, S, and others. 相似文献