Changes in DMS production and flux in relation to decadal shifts in ocean circulation     

J. ICARUS ALLEN  STEPHEN D. ARCHER  JERRY C. BLACKFORD  FRANCIS J. GILBERT  ARNOLD H. TAYLOR 《Tellus. Series B, Chemical and physical meteorology》2006,58(3):242-254

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红河-哀牢山断裂带钾质碱性岩锆石LA-ICP-MS U-Pb年龄及地质意义     

梁华英  孙卫东  张玉泉  Ian H.Campbell 《矿物岩石地球化学通报》2008,27(Z1)

哀牢山-红河断裂是东南亚地区主要断裂,Tapponnier [1,2]和Leloup等[3]认为它与南海的形成有密切的内在成因联系.因此,分析这一深大断裂开始活动的时间,对了解南海的形成及东南亚的构造演化有着重要的意义.目前对这条深大断裂开始活动的时间有人[4]认为晚于27 Ma,即在南海打开之后,因而两者没成因联系;较多的学者[5～9]认为其活动期限与南海的开合基本一致,均为32～16Ma.  相似文献   

藏东玉龙超大型斑岩铜矿床成岩成矿系统时间跨度分析   总被引：12，自引：5，他引：7  

梁华英  莫济海  孙卫东  喻亨祥  张玉泉  Charllote M. ALLEN 《岩石学报》2008,24(10):2352-2358

藏东玉龙超大型斑岩铜矿床是目前西藏发现的最大斑岩铜矿床,含铜岩体主要由早期石英二长斑岩及晚期正长花岗斑岩组成。本文用LA-ICP-MS法测定早期石英二长斑岩及晚期正长花岗斑岩锆石U-Pb年龄及Ar-Ar法测定钾质蚀变带黑云母的Ar-Ar年龄,发现玉龙含矿斑岩体早期石英二长斑岩锆石LA-ICP-MS U-Pb年龄(41.3±0.3Ma, MSWD=0.92)与晚期正长花岗斑岩锆石LA-ICP-MS U-Pb年龄(41.3±0.2Ma, MSWD=1.24)基本相同,也和黑云母Ar-Ar坪年龄(41.7±0.8Ma)及等时线年龄(41.3±0.8Ma)在误差范围内一致。玉龙斑岩铜矿早期及晚期岩体锆石U-Pb年龄一致表明含矿岩体在地质上的早期及晚期主要是岩浆在较短时间内脉动侵入所致。玉龙含矿岩体锆石U-Pb年龄(封闭温度约800℃)、³⁹Ar-⁴⁰Ar 年龄(封闭温度约300℃)及前人获得的Re-Os年龄40.1±1.8Ma(封闭温度约500℃)在误差范围内基本一致,表明含矿岩体岩体快速冷却,玉龙超大型斑岩铜矿床成岩成矿系统时间跨度小于1Ma。  相似文献   

Identifying signals from intermittent low-frequency behaving systems     

A. HANNACHI  M. R. ALLEN 《地球，A辑:动力气象学与海洋学》2001,53(4):469-480

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AN INTERPRETATION AND ANALYSIS OF RECUMBENT-FOLDED DEFORMED CROSS-BEDDING   总被引：2，自引：0，他引：2  

J. R. L. ALLEN  N. L. BANKS 《Sedimentology》1972,19(3-4):257-283

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A REVIEW OF THE ORIGIN AND CHARACTERISTICS OF RECENT ALLUVIAL SEDIMENTS   总被引：12，自引：1，他引：12  

J. R. L. ALLEN 《Sedimentology》1965,5(2):89-191

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THE CLASSIFICATION OF CROSS-STRATIFIED UNITS, FURTHER DISCUSSlON     

J. R. L. ALLEN 《Sedimentology》1965,5(3):252-254

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Zoisite--Anorthite--Calcite Stability Relations in H2O--CO2 Fluids at 5000 Bars: An Experimental and SEM Study     

ALLEN  JOHN M.; FAWCETT  J. J. 《Journal of Petrology》1982,23(2):215-239

The reaction 2 zoisite + CO₂ = 3 anorthite + calcite + H₂O hasbeen reversed experimentally in cold-seal pressure vessels usingnatural phases and H2O–C02 fluids generated by water-silveroxalate mixtures. Equilibrium has been determined at 5000 50bars, 599 9 °C and 0–075 ± 0–010 X_{CO2.Extrapolation using the MRK equation of Kerrick & Jacobs(1981) gives an equilibrium curve of negative T–X slopeconsistent with bracketing runs at 500, 550 and 650 °C.The curve agrees only with a new bracket of Nitsch (in Hoschek,1980), and is at higher XCo2} than all other experimental determinationsand at lower XCO₂ than those calculated from the thermodynamicdata of Helgeson et al. (1978). Discrepancies are attributedto differences in starting materials and small errors in thethermodynamic properties of the phases. Reaction direction and equilibrium have been determined by observingsurface textures of run products by SEM. Growth and solutiontextures are non-equivalent, permitting unequivocal determinationof reaction direction even where the extent of reaction is small,an advantage over conventional and insensitive XRD methods whichmeasure bulk changes in the charge. Dissolution features ofanorthite and zoisite are defect-related indicating controlby surface reaction, whereas calcite dissolves by both surfacereaction and diffusion controlled processes. Margarite forms in most runs below 585 °C. Textural features,its restriction to the margarite stability field and comparisonwith feldspar solubility data demonstrate it is an equilibriumphase formed by incongruent solubility of anorthite and zoisitein H₂O-CO₂ fluids. Quench phases formed from the solute areconsequently silica-rich, with implications for metasomaticprocesses in feldspar–epidote–bearing rock and fluidsystems. Absence of margarite from runs with anorthite, zoisiteand calcite in the zoisite stability field is apparently dueto the fast growth rate of zoisite. The full equilibrium assemblageis zoisite–anorthite–calcite–margarite atthese temperatures, and the degeneracy of the model system isunobtainable in experiments, and presumably, in nature.  相似文献   

Sediment dispersal and palaeohydraulics of Oligocene rivers in the eastern Ebro Basin     

PHILIP ALLEN  MARIA MANGE-RAJETZKY 《Sedimentology》1982,29(5):705-716

Mapping of heavy mineral associations and diagnostic accessories in Oligocene sediments of the eastern Ebro Basin has revealed two major provinces and several sub-provinces. The Pyrenean Province is characterized by an apatite-tourmaline-garnet association with diagnostic staurolite in the west (western Pyrenean Sub-Province) and micaceous composite grains plus chloritoid in the east (eastern Pyrenean Sub-Province). The Catalanides Province is characterized by an ultrastable angular brown tourmaline-staurolite association with kyanite in the south-west (Montsant Sub-Province), faceted garnets and rounded tourmalines in an intermediate position (St Miquel del Montclar Sub-Province) and in the north-east rounded and green tourmalines admixed with clinopyroxene, apatite and micas derived from the Pyrenees (Montserrat Sub-Province). Palaeodischarges have been estimated from 30 channels distributed throughout both major provinces. A gradual decrease in river discharge through Oligocene times is indicated for the rivers of Catalanides parentage, although the discharges of high-sinuosity streams alone remain uniform. This decrease through time of Catalanides drainage competitiveness is reflected in the greater areal extent of the Pyrenean petrological province together with a progressive displacement south or south-eastwards of basinal lacustrine facies. The increasing dominance of Pyrenean drainage during the Oligocene may be due to more prolonged tectonic activity in the Pyrenees compared to the more quiescent Catalanides.  相似文献   

Determination of Niobium in 15 USGS Standard Rocks by NEutron Activation Analysis     

R.O. ALLEN  E. STEINNES 《Geostandards and Geoanalytical Research》1979,3(1):57-60

The niobium concentrations in 15 U.S.G.S. standard rocks were measured by neutron activation analysis. The niobium was separated from the rock matrix (in the presence of ⁹⁵Nb tracer, which was used to measure the fraction recovered) before irradiation to improve the sensitivity. Results of this work are compared with those obtained by other techniques. Some results obtained by multielement X-ray fluorescence procedures agree well with the present data, but a systematic disagreement exists between these and the spectrophotometric data.  相似文献