贵州贞丰烂泥沟卡林型金矿床含砷黄铁矿Re-Os同位素测年及地质意义   总被引：19，自引：0，他引：19       下载免费PDF全文

陈懋弘毛景文  屈文俊吴六灵 Phillip J. UTTLEY Tony NORMAN郑建民  秦运忠 《地质论评》2007,53(3):371-382

贵州贞丰烂泥沟金矿(现称锦丰金矿)是滇黔桂“金三角”已知最大的卡林型金矿床,矿体赋存于断层破碎带内,最主要的载金矿物是具环带结构的含砷黄铁矿。本文运用Re-Os同位素法对该矿床的9个含砷黄铁矿样品进行了两次测试,成功获得10-9～10-12级Re-Os同位素数据:Re0.1257～1.233ng/g,Os6.75～33.50pg/g,等时线年龄为193±13Ma,反映其成矿时代为早侏罗世。等时线的初始n(187Os)/n(188Os)值为1.127±0.043,指示成矿物质来源于地壳而不是地幔。结合其他资料,初步建立其成矿模式为:盆地流体不断地从沉积物中萃取出包括金在内的成矿组分,形成含矿流体。印支期挤压造山期间,含矿流体沿不整合接触面和同生断层向上运动,造山后的伸展含矿流体进入减压扩容空间沉淀形成超大型金矿床。成矿作用发生在从印支期挤压造山向燕山期伸展转变的构造转换期。该模式与本文得到的成矿年龄和初始比值相吻合。  相似文献   

COMMENTS ON PAPER ENTITLED "SOME MODEL EXPERIMENTS RELATING TO ELECTRO-MAGNETIC PROSPECTING WITH SPECIAL REFERENCE TO AIRBORNE WORK" BY E. H. HEDSTROM and D. S. PARASNIS in Geophysical Prospecting, vol. VI, number 4, December 1958     

NORMAN R. PATERSON 《Geophysical Prospecting》1959,7(4):435-447

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Changes in School Geography since 1945     

NORMAN H. WHATMAN 《New Zealand geographer》1969,25(2):161-176

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Use of remote sensing for evapotranspiration monitoring over land surfaces   总被引：1，自引：0，他引：1  

W. P. KUSTAS  J. M. NORMAN 《水文科学杂志》2013,58(4):495-516

Abstract

Monitoring evapotranspiration (ET) at large scales is important for assessing climate and anthropogenic effects on natural and agricultural ecosystems. This paper describes techniques used in evaluating ET with remote sensing, which is the only technology that can efficiently and economically provide regional and global coverage. Some of the empirical/statistical techniques have been used operationally with satellite data for computing daily ET at regional scales. The more complex numerical simulation models require detailed input parameters that may limit their application to regions containing a large database of soils and vegetation properties. Current efforts are being directed towards simplifying the parameter requirements of these models. Essentially all energy balance models rely on an estimate of the available energy (net radiation less soil heat flux). Net radiation is not easily determined from space, although progress is being made. Simplified approaches for estimating soil heat flux appear promising for operational applications. In addition, most ET models utilize remote sensing data in the shortwave and thermal wavelengths to measure key boundary conditions. Differences between the radiometric surface temperature and aerodynamic temperature can be significant and progress in incorporating this effect is evident. Atmospheric effects on optical data are significant, and optical sensors cannot see through clouds. This has led some to use microwave observations as a surrogate for optical data to provide estimates of surface moisture and surface temperature; preliminary results are encouraging. The approaches that appear most promising use surface temperature and vegetation indices or a time rate of change in surface temperature coupled to an atmospheric boundary layer model. For many of these models, differences with ET observations can be as low as 20% from hourly to daily time scales, approaching the level of uncertainty in the measurement of ET and contradicting some recent pessimistic conclusions concerning the utility of remotely sensed radiometric surface temperature for determining the surface energy balance.  相似文献   

Petrology of the Partridge River Intrusion, Duluth   总被引：2，自引：1，他引：2  

GRANT  NORMAN K.; CHALOKWU  CHRISTOPHER I. 《Journal of Petrology》1992,33(5):1007-1038

Drill core DDH-221 was drilled for the Minnamax Project by AMAX Exploration, Inc., as part of the exploration for Cu-Ni sulfidesin the basal rocks of the northwestern margin of the DuluthComplex. The drill core intersects 525 m of the Partridge RiverIntrusion before passing into the Virginia Formation footwall.The rocks in the drill core comprise plagioclase and olivinecumulates, with troctolite and olivine gabbro as the most commonrock types. Sulfide- and oxide-bearing gabbros are present inthe lowest 100 m of the core where decreases in the crystalsizes of plagioclase and olivine, and the appearance of ophitictextures adjacent to the footwall, indicate that the chilledmargin of the intrusion has been preserved (Chalokwu & Grant,1990). The concentrations of incompatible elements in the wholerocks and the iron contents of olivine and pyroxenes all increasesharply in the lowest 100 m of the drill core (Chalokwu &Grant, 1990), and are interpreted as the downward increase inintercumulus liquid now preserved as intercumulus phases, andthe reaction of this liquid with olivine and pyroxenes. Mass, balance calculations for rocks containing widely differentvolumes of intercumulus phases show that the intercumulus liquidwas a chemically uniform ferrodiorite that can be derived fromKeweenawan high-alumina olivine tholeiite by plagioclase (An₆₃),clinopyroxene (En₅₀Fs₁₀Wo₄₀), and olivine (Fo₇₁) fractionation. Initial ⁸⁷Sr/⁸⁶Sr values for plagioclase range between 0–704764and O-706335, with the highest values occurring adjacent tothe footwall Virginia Formation, and the lowest at intermediatedepths in the core. These variations are similar to ⁸⁷Sr/⁸⁶Srvalues reported earlier by Grant & Moiling (1981) From theadjacent core DDH-295, although the values are all greater thanpublished initial ratios for the least altered Keweenawan lavas.We attribute the isotopic variations in core DDH-221 to isotopicheterogeneities in the Partridge River Intrusion magmas, andto limited assimilation of the Virginia Formation within 50m of the footwall. Rare-earth and other trace elements in the intercumulus liquidfrom core DDH-221 have similar distributions to the same elementsin Keweenawan basic to intermediate lavas. We conclude that the rocks of the Partridge River Intrusionsampled in drill core DDH-221 comprise a mechanical mixtureof cumulus plagioclase and olivine and intercumulus liquid thatwere not in equilibrium with each other, and that the intercumulusliquid was broadly consanguineous with Keweenawan high-aluminaolivine tholeiite lavas, but was modified to a greater extentby assimilative exchange with continental crust. After emplacement,the crystal-liquid mixture was modified by flotation of thecumulus plagioclase out of the basal zone, and by limited —but not ubiquitous — assimilation of footwall VirginiaFormation.  相似文献   

The Evolution of the Upper Mantle beneath the Canary Islands: Information from Trace Elements and Sr isotope Ratios in Minerals in Mantle Xenoliths   总被引：4，自引：1，他引：3  

NEUMANN  ELSE-RAGNHILD; GRIFFIN  WILLIAM LINDSEY; PEARSON  NORMAN J.; O'REILLY  SUZANNE YVONNE 《Journal of Petrology》2004,45(12):2573-2612

Laser ablation microprobe data are presented for olivine, orthopyroxeneand clinopyroxene in spinel harzburgite and lherzolite xenolithsfrom La Palma, Hierro, and Lanzarote, and new whole-rock trace-elementdata for xenoliths from Hierro and Lanzarote. The xenolithsshow evidence of strong major, trace element and Sr isotopedepletion (⁸⁷Sr/⁸⁶Sr 0·7027 in clinopyroxene in themost refractory harzburgites) overprinted by metasomatism. Thelow Sr isotope ratios are not compatible with the former suggestionof a mantle plume in the area during opening of the AtlanticOcean. Estimates suggest that the composition of the originaloceanic lithospheric mantle beneath the Canary Islands correspondsto the residues after 25–30% fractional melting of primordialmantle material; it is thus significantly more refractory than‘normal’ mid-ocean ridge basalt (MORB) mantle. Thetrace element compositions and Sr isotopic ratios of the mineralsleast affected by metasomatization indicate that the upper mantlebeneath the Canary Islands originally formed as highly refractoryoceanic lithosphere during the opening of the Atlantic Oceanin the area. During the Canarian intraplate event the uppermantle was metasomatized; the metasomatic processes includecryptic metasomatism, resetting of the Sr–Nd isotopicratios to values within the range of Canary Islands basalts,formation of minor amounts of phlogopite, and melt–wall-rockreactions. The upper mantle beneath Tenerife and La Palma isstrongly metasomatized by carbonatitic or carbonaceous meltshighly enriched in light rare earth elements (REE) relativeto heavy REE, and depleted in Zr–Hf and Ti relative toREE. In the lithospheric mantle beneath Hierro and Lanzarote,metasomatism has been relatively weak, and appears to be causedby high-Si melts producing concave-upwards trace element patternsin clinopyroxene with weak negative Zr and Ti anomalies. Ti–Al–Fe-richharzburgites/lherzolites, dunites, wehrlites and clinopyroxenitesformed from mildly alkaline basaltic melts (similar to thosethat dominate the exposed parts of the islands), and appearto be mainly restricted to magma conduits; the alkali basaltmelts have caused only local metasomatism in the mantle wall-rocksof such conduits. The various metasomatic fluids formed as theresults of immiscible separations, melt–wall-rock reactionsand chromatographic fractionation either from a CO₂-rich basalticprimary melt, or, alternatively, from a basaltic and a siliceouscarbonatite or carbonaceous silicate melt. KEY WORDS: mantle xenoliths; mantle minerals; trace elements; depletion; carbonatite metasomatism  相似文献   

A glove box for the fine-scale subsampling of sediment box cores   总被引：1，自引：0，他引：1  

HARRY M. EDENBORN  ALFONSO MUCCI  NELSON BELZILE  JEAN LEBEL  NORMAN SILVERBERG  BJØRN SUNDBY† 《Sedimentology》1986,33(1):147-150

The construction and operation of a glove box which allows the fine-scale vertical subsampling of sediment box cores under a low oxygen atmosphere is described.  相似文献   

An Archean(?) to Paleozoic Evolution for a Garnet Peridotite Lens with Sub-Baltic Shield Affinity within the Seve Nappe Complex of Jamtland, Sweden, Central Scandinavian Caledonides   总被引：2，自引：0，他引：2  

BRUECKNER  HANNES K.; VAN ROERMUND  HERMAN L. M.; PEARSON  NORMAN J. 《Journal of Petrology》2004,45(2):415-437

Mineralogical, isotopic, geochemical and geochronological evidencedemonstrates that the Friningen body, a garnet peridotite bodycontaining garnet pyroxenite layers in the Seve Nappe Complex(SNC) of Northern Jämtland, Sweden, represents old, certainlyProterozoic and possibly Archean, lithosphere that became incorporatedinto the Caledonian tectonic edifice during crustal subductioninto the mantle at c. 450 Ma. Both garnet peridotite and pyroxenitecontain two (M₁ and M₂) generations of garnet-bearing assemblagesseparated by the formation of two-pyroxene, spinel symplectitearound the M₁ garnet and the crystallization of low-Cr spinel_1Cin the matrix. These textures suggest initial high-pressure(HP) crystallization of garnet peridotite and pyroxenite succeededby decompression into the spinel stability field, followed byrecompression into the garnet peridotite facies. Some pyroxenitelayers appear to be characterized solely by M₂ assemblages withstretched garnet as large as several centimeters. Laser ablationmicroprobe–inductively coupled plasma mass spectrometryRe–Os analyses of single sulfide grains generally definemeaningless model ages suggesting more than one episode of Reand/or Os addition and/or loss to the body. Pentlandite grainsfrom a single polished slab of one garnet peridotite, however,define a linear array on an Re–Os isochron diagram that,if interpreted as an errorchron, suggests an Archean melt extractionevent that left behind the depleted dunite and harzburgite bodiesthat characterize the SNC. Refertilization of this mantle bymelts associated with the development of the pyroxenite layersis indicated by enriched clinopyroxene Sr–Nd isotope ratios,and by parallel large ion lithophile-enriched trace elementpatterns in clinopyroxene from pyroxenite and the immediatelyadjacent peridotite. Clinopyroxene and whole-rock model Sm–Ndages (T_DM = 1·1–2·2 Ga) indicate that fertilizationtook place in Proterozoic times. Sm–Nd garnet₂–clinopyroxene₂–wholerock ± orthopyroxene₂ mineral isochrons from three pyroxenitelayers define overlapping ages of 452·1 ± 7·5and 448 ± 13 Ma and 451 ± 43 Ma (2  相似文献   

Modelling of hydrogen and oxygen isotope compositions for local precipitation   总被引：3，自引：0，他引：3  

HAIDONG PENG  BERNHARD MAYER  ANN-LISE NORMAN  H. ROY KROUSE 《Tellus. Series B, Chemical and physical meteorology》2005,57(4):273-282

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Orogeny, magmatism and metallogeny in Europe     

NORMAN E. BUTCHER  REW A. MCMILLAN 《Geology Today》1988,4(2):52-53

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