Facies analyses and volcanic setting of the giant Neves Corvo massive sulfide deposit,Iberian Pyrite Belt,Portugal     

Carlos J. P. Rosa  Jocelyn McPhie  Jorge M. R. S. Relvas  Zélia Pereira  Tomás Oliveira  Nelson Pacheco 《Mineralium Deposita》2008,43(4):449-466

In the Iberian Pyrite Belt, volcanic rocks are relatively scarce, accounting for approximately only 25% of the geologic record, with the remaining 75% consisting of sedimentary units. This association is very clear in the host succession to the Neves Corvo massive sulfide deposit in Portugal. The Neves Corvo host succession comprises the products of explosive and effusive rhyolitic eruptions intercalated with mudstone that records a submarine below-wave-base environment and provides precise biostratigraphic age constraints. The first and second volcanic events involved eruptions at local intrabasinal vents. The first event generated thick beds of fiamme breccia that are late Famennian in age. The fiamme were originally pumice clasts produced by explosive eruptions and were subsequently compacted. The second event was the late Strunian (latest Famennian) effusion of rhyolitic lava that was pervasively quench-fragmented. The third and final event is younger than the massive sulfide deposits poorly represented in the mine area and minor compared with the two other events. The integration of biostratigraphic data with the volcanic facies architecture indicates that the Neves Corvo ore deposits are similar in age to the late Strunian rhyolitic lava. Although regionally the Iberian Pyrite Belt is essentially a sedimentary succession, ore formation at Neves Corvo can be closely linked to discrete volcanic events that produced a relatively narrow range of volcanic facies.  相似文献   

The effect of metal complexation on hydrogen sulfide transport across the sea-air interface     

Scott Elliott  F. Sherwood Rowland 《Journal of Atmospheric Chemistry》1990,10(3):315-327

Hydrogen sulfide dissolved in surface seawater is distributed into free forms which include the volatile neutral H₂S and its conjugate anions, and also into a set of involatile metal complexes. Calculation of the sulfide fraction capable of supporting sea-air flux is sensitive to large uncertainties in complexation equilibrium relationships, both for the sulfides themselves, and for organic ligands competing with them to coordinate dissolved copper. Saturation can be achieved relative to the troposphere if metal interactions are minimized, or if strong sulfide binders are titrated.  相似文献   

Lacustrine massive mudrock in the Eocene Jiyang Depression,Bohai Bay Basin,China: Nature,origin and significance     

《Marine and Petroleum Geology》2016

Massive mudrock refers to mudrock with internally homogeneous characteristics and an absence of laminae. Previous studies were primarily conducted in the marine environment, while notably few studies have investigated lacustrine massive mudrock. Based on core observation in the lacustrine environment of the Jiyang Depression, Bohai Bay Basin, China, massive mudrock is a common deep water fine-grained sedimentary rock. There are two types of massive mudrock. Both types are sharply delineated at the bottom and top contacts, abundant in angular terrigenous debris, and associated with oxygen-rich (higher than 2 ml O₂/L H₂O) but lower water salinities in comparison to adjacent black shales. In addition, type 1 is laterally isolated and contains abundant sand injections and contorted layers formed in the depositional process, but type 2 exactly distributes in the distal part of deep water gravity-driven sandstone units, and shows scoured bases, high-angle mineral crytsals, and fining-upward trend. It is suggested that type 1 is a muddy mass transport deposit (MMTD) formed by slide, slump, and/or debris flow, and type 2 is a turbiditic mudrock deposited by settling from dilute turbidity currents. A warm and humid climate and high subsidence rate are two main triggering events. Because of its mass movement nature, MMTD preserves the mineralogic composition and organic matter characteristics of the source sediment. By contrast, dilute turbidity currents are able to greatly entrain biochemically-formed micrite and planktonic organisms from the water column, and deposit them in the turbiditic mudrock. Because of their different ability to deposit organic matter, MMTD have poor or fair source rock potential, but the turbiditic mudrock is able to be a potentially effective source rock. The minerals in the massive mudrock are disorganized and chaotic, which cause fractures to develop in various directions, thereby, enhancing the vertical migration of oil and gas molecules to horizontal wellbore in shale reservoir exploitation.  相似文献   

冲绳海槽Jade热液区块状硫化物中流体包裹体的氦、氖、氩同位素组成   总被引：3，自引：1，他引：3       下载免费PDF全文

曾志刚  秦蕴珊  翟世奎 《海洋学报》2003,25(4):36-42

对冲绳海槽Jade热液区块状硫化物中流体包裹体的氦、氖和氩同位素组成进行了测定,流体包裹体的3He/4He比值为(6.2～10.1)Ra,均值为7.8Ra,与大洋中脊玄武岩一致[3He/4He≈(6～11)Ra],20Ne/22Ne比值为10.7～11.3,明显高于大气值(9.8),而40Ar/36Ar比值的变化范围在287～334之间,接近大气值(295.5),这些结果表明,块状硫化物中热液流体捕获的稀有气体是地幔和海水源组分混合的产物,且流体包裹体中的氦主要来自地幔,氖和氩主要来自海水。  相似文献   

Hydrodynamics of Supernova Evolution in the Winds of Massive Stars     

Vikram V. Dwarkadas 《Astrophysics and Space Science》2007,307(1-3):153-158

Core-Collapse supernovae arise from stars greater than 8 M_⊙. These stars lose a considerable amount of mass during their lifetime, which accumulates around the star forming wind-blown bubbles. Upon the death of the star in a spectacular explosion, the resulting SN shock wave will interact with this modified medium. We study the evolution of the shock wave, and investigate the properties of this interaction. We concentrate on the evolution of the SN shock wave in the medium around a 35 solar mass star. We discuss the hydrodynamics of the resulting interaction, the formation and growth of instabilities, and deviations from sphericity.  相似文献   

辽宁红透山块状硫化物矿床蚀变带元素迁移特征及定量计算   总被引：2，自引：1，他引：1  

郑远川  顾连兴  汤晓茜  吴昌志  李春海  刘四海 《矿床地质》2010,29(5):785-809

辽宁红透山块状硫化物矿床（MSD）位于华北地台东北部的浑北花岗岩-绿岩地体内,矿区岩石在30～28 亿年期间受到了600～650℃的高级角闪岩相变质。研究结果表明,广泛分布于红透山层状矿体下盘数百米处的和直接产于矿体下盘的堇青-直闪片麻岩,分别代表了变质后的MSD成矿系统以绿泥石化为特征的半整合和筒状不整合海底热液蚀变带。微量元素特征显示,层状堇青-直闪片麻岩的原岩并非同一种岩石,而是由5种不同岩性的岩石组成,筒状堇青-直闪片麻岩的原岩主要由流纹质岩石组成,而在堇青-直闪片麻岩走向上与之过渡的角闪片麻岩和黑云片麻岩则代表了不同岩性蚀变岩的未蚀变原岩。质量变化计算表明,相对于未蚀变原岩而言,两种蚀变岩的成分发生了显著变化,其中层状堇青-直闪片麻岩的Fe、Mg发生了富集,Na、K、Ca、Cu、Pb和Zn等元素被迁出,而筒状堇青-直闪片麻岩的Fe、Mg、Si、Na、Pb、Cu和Zn等元素则发生了富集,K被迁出。重稀土元素（HREE）和高场强元素(Zr、Ti、Nb、Hf和Ta)在海底热液蚀变过程中保持惰性,而Rb、Sr、Ba和轻稀土元素（LREE,尤其是Eu）则被强烈的迁出。这些元素变化特征表明海底热液蚀变以绿泥石化和硅化为特征,同时海底水-岩反应体系具有高水/岩比值。层状堇青-直闪片麻岩可作为红透山矿区成矿潜力评价的重要依据,而含硫化物石英脉的筒状堇青-直闪片麻岩不但本身可成为工业矿体,还可作为上覆层状矿体的近矿找矿标志。  相似文献   

黔西南、桂北地区微细浸染型金矿床砷、锑、汞、铊元素及矿物组合特征   总被引：2，自引：0，他引：2  

钱汉东  陈武  胡勇 《高校地质学报》1995,1(2):5-52

本文结合野外地质调查和有关的低温硫化物相平衡实验结果，对黔西南、桂北地区的浅成低温热液浸染型金矿床中与金共（伴）生的硫化物矿物组合、地球化学特征及其成矿作用机制进行了综合分析研究。研究表明，与金矿化共（伴）生的砷、锑、汞和铊等地球化学指示元素及其矿物组合不仅具有成生方面的联系，而且可以作为寻找金的一种特征的标型标志。  相似文献   

地质流体力学研究的进展     

邓吉牛 《地质科技情报》1993,12(3):39-44

归纳了地质流体力学研究中目前常用的三个基础理论,即双扩散对流理论,边界层理论和相似理论,重点总结了其在岩浆岩石学、成矿学、地球物理学及沉积岩石学等研究领域内的进展。  相似文献   

The use of electron backscatter diffraction and orientation contrast imaging as tools for sulphide textural studies: example from the Greens Creek deposit (Alaska)     

Katja?Freitag  Alan?P.?BoyleEmail author  Eric?Nelson  Murray?Hitzman  James?Churchill  Magda?Lopez-Pedrosa 《Mineralium Deposita》2004,39(1):103-113

The Greens Creek polymetallic massive sulphide deposit is hosted in a typical polyphase deformed lower greenschist facies orogenic setting. The structure of the host rocks is well constrained, exhibiting a series of three superimposed ductile deformations followed by two brittle episodes. The ore is found both in fold hinges where early-formed depositional features are preserved and in fold limbs where primary features are typically strongly modified or obliterated. Samples from both settings have been investigated using electron backscatter diffraction (EBSD) coupled with forescatter orientation contrast (OC) imaging in order to observe the effects of deformation and lower greenschist facies metamorphism on pyrite. Results suggest that colloform pyrite may preserve information relevant to palaeoenvironment, that apparently simple textures are generally more complex, and that pyrite can deform plastically by dislocation glide and creep processes at lower temperatures and/or strain rates than generally accepted. This analysis indicates that EBSD and OC imaging provide powerful tools for observing textural relationships in pyrite that are not shown by more traditional methods. They should become routine tools for pyrite texture analysis.Editorial handling: D. Lentz  相似文献   

Zn–Pb–Cu volcanic-hosted massive sulphide deposits: criteria for distinguishing brine pool-type from black smoker-type sulphide deposition     

M. Solomon  F. Tornos  R. R. Large  J. N. P. Badham  R. A. Both  Khin Zaw 《Ore Geology Reviews》2004,25(3-4):259-283

Eight Zn–Pb–Cu massive sulphide deposits that appear to have formed on the sea floor (seven in Spain, one in Tasmania) are believed to have been precipitated in brine pools, based on the salinities and temperatures of fluid inclusions in underlying stockworks. Comparing the geological features of these deposits with those of the Zn–Pb–Cu massive sulphide ores of the Hokuroku Basin, Japan, which have formed as mounds from buoyant fluids of low salinity, shows that brine pool deposits have: (1) potentially very large size and tonnage, and high aspect ratio, (2) higher Zn/Cu and Fe/Cu values, (3) no evidence of chimneys, (4) relatively abundant framboidal pyrite and primary mineral banding, (5) reduced mineral assemblages (pyrite-arsenopyrite/pyrrhotite), and minor or rare barite in the massive sulphide, (6) associated stratiform and/or vein carbonates, (7) relatively unimportant zone refining, (8) lack of vertical variation in sphalerite and sulphur isotopic compositions, and (9) evidence of local bacterial sulphate reduction. Application of these criteria to the Rosebery deposit in Tasmania, for which there are no fluid inclusion data, leads to the conclusion that the southern section was deposited as separate lenses in a brine-filled basin or basins. Other potential candidates include Brunswick no. 12 and Heath Steele (Canada), Woodlawn and Captains Flat (New South Wales), Hercules and Que River (Tasmania), and Tharsis and the orebodies at Aljustrel (Spain and Portugal). Recently published fluid inclusion data for Gacun (China) and Mount Chalmers (Queensland) suggest that not all ores deposited from highly saline fluids have reduced mineral assemblages.  相似文献