Research directions for information and communication technology and society in Geography     

Melissa R. Gilbert 《Geoforum》2005,36(3):277-279

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Examining tendencies of in-plane rupture to migrate to material interfaces     

Gilbert B. Brietzke  Yehuda Ben-Zion 《Geophysical Journal International》2006,167(2):807-819

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Rare earth element mobility in the Roffna Gneiss,Switzerland   总被引：1，自引：0，他引：1  

Robert D. Vocke Jr.  Gilbert N. Hanson  Marc Grünenfelder 《Contributions to Mineralogy and Petrology》1987,95(2):145-154

The Roffna Gneiss, a deformed Hercynian granite porphyry within the Penninic nappes of eastern Switzerland, underwent extreme cataclasis with the progressive development of phengite towards the margins of the nappe under conditions of the glaucophane schist to greenschist facies. This resulted in the selective mobilization of major and trace elements over distances of 10's to 100's of meters and the resetting of the Rb — Sr whole rock isotopic systems some 100 my ago. The component ratios and compositionvolume relationships of progressively deformed gneiss samples studied here suggest that this process was essentially isovolumetric. The mineralogy of the deformation sequence appears to have been controlled by a reaction involving the breakdown of microcline, albite and biotite and the formation of phengite and quartz. The fluids introduced Mg and H₂O, promoting the development of phengite, and removed the Na being released by the breakdown of albite. The fluids were most probably derived from the surrounding Triassic carbonates and quartzites. These relatively high fO₂ and carbonate rich fluids also introduced rare earth elements (REE) into the gneiss. The gneiss was progressively enriched in Eu up to 60%, Y up to 40%, and Yb up to 100%. These enrichments are associated with the development of epitaxial xenotime around zircon in the most phengite-rich sample. While the REE were mobile, uranium and thorium were essentially immobile. The formation of xenotime was suggested to explain the observed heavy REE enrichment when large differences in the REE contents were found for replicate analyses using HF and then lithium metaborate for dissolution. These differences arose because xenotime, like monazite, can be difficult (if not impossible) to dissolve in hydrofluoric acid. Due to the possibility of incomplete sample dissolution, we now recommend fusion with lithium metaborate for all REE, Lu — Hf or Sm — Nd studies.  相似文献   

Pogo and Pangaea     

Herbert Frey  Robert Langel  Gilbert Mead  Keith Brown 《Tectonophysics》1983,95(3-4)

Long wavelength magnetic anomalies of crustal origin derived from the POGO and MAGSAT satellite data often display a strong continuity across the now-rifted continental margins when the continents are reassembled into Pangaea. These anomalies predate the breakup of the supercontinent and represent major blocks whose crustal properties are broadly similar even though those blocks are no longer contiguous.  相似文献   

Comparison of the structures of humic substances from aquatic and terrestrial sources by pyrolysis gas chromatography-mass spectrometry     

M.A. Wilson  R.P. Philp  A.H. Gillam  T.D. Gilbert  K.R. Tate 《Geochimica et cosmochimica acta》1983,47(3):497-502

Four humic extracts isolated from terrestrial, mahne, plankton and freshwater sources have been investigated by pyrolysis-gas chromatography-mass spectrometry. The results show that substantial quantities of phenols (some not derived from lignin), pyrroles and nitrites (derived from proteins, nucleic acids or porphyrins) are decomposition products. Small amounts of furans (derived from carbohydrates) and unsaturated ketones (derived from polycarboxylic aliphatic acids) are also present. The results illustrate how parent material, transport factors and biological activity affect the composition of humic extracts.  相似文献   

CO₂-poor composition of the fluid attending Franciscan and Sanbagawa low-grade metamorphism     

W.G Ernst 《Geochimica et cosmochimica acta》1972

Previous phase equilibrium and oxygen isotopic researches on the high-pressure, low-temperature metamorphic rocks of the Franciscan and Sanbagawa blueschist type terranes have demonstrated the near ubiquity of a fluid at high (≈ total) pressure and its oxygen-rich nature during metamorphism. The coexistence of quartz with a CaCO₃ polymorph instead of wollastonite, and of sphene rather than rutile + quartz + calcium carbonate in these rocks places narrow, rather low limits on the partial pressures of CO₂, as computed in this note; equilibrium calculations indicate that the mole fraction of carbon dioxide in the fluid must have been less than about 0.04 in the Sanbagawa terrane and less than 0.01 in the Franciscan terrane. The rocks are not sulfated or strongly oxidized, hence the only other likely component which could comprise the balance of this phase is H₂O. Evidently metamorphism in the Sanbagawa belt and particularly in the Franciscan terrane must have taken place in the presence of a highly aqueous fluid.  相似文献   

Distribution of gold,silver, copper,lead and zinc in the productive Marysville stock,Montana     

Erwin Mantei  Ernst Bolter  Zuhair Al Shaieb 《Mineralium Deposita》1970,5(2):184-190

125 whole rock samples from the productive Marysville, Montana, granodiorite and the surrounding metamorphic rocks were analyzed by neutron activation analysis for gold and silver, and by atomic absorption for copper, lead and zinc. In the vicinity of known gold veins, anomalous values for gold and silver were found in both types of bedrock. Anomalies for the base metals were much less pronounced. The results indicate that systematic analysis of igneous bodies could be useful in exploration for hydrothermal ore deposits.

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Zusammenfassung 125 Gesteinsproben des sogenannten produktiven Granodiorits in Marysville (Montana) wurden durch Neutronenaktivierungsanalyse auf Gold und Silber und mittels Atomabsorptionsanalyse auf Kupfer, Blei und Zink analysiert. In der Nähe bekannter Goldadern wurden in beiden Gesteinsarten ungewöhnlich hohe Gold- und Silber-Werte gefunden. Anomale Werte für Kupfer, Blei und Zink waren seltener. Die Ergebnisse zeigen, daß eine systematische Untersuchung magmatischer Gesteinskomplexe bei der Suche nach hydrothermalen Erzlagerstätten von Nutzen sein kann.

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Folgerungen für die Entstehung der Basalte aus dem speziellen Auftreten der Pyroxene in diesen Gesteinen     

Prof. Dr. Th. Ernst 《International Journal of Earth Sciences》1962,51(2):364-374

Zusammenfassung Die früheren Angaben über die Pyroxenführung, besonders über den Gehalt an rhombischem Pyroxen, wurden in den Basalten der südwestlichen Ausläufer des Vogelsberges überprüft. Es kann in Abhängigkeit vom SiO₂-Gehalt dieser Gesteine eine Beziehung über die Zusammensetzung der Basalte und die Art der auftretenden Pyroxene aufgestellt werden. Vereinfacht ergibt sich, daß die Olivinbasalte keinen rhombischen Pyroxen in der Grundmasse führen - abgesehen von den Olivinknollen - und die Gesteine mit Bronzitführung dem gabbrodioritischen bzw. dioritischen Magmentyp angehören. Daneben kommt Pigeonit in weiter Verbreitung vor. Diese Befunde unterstützen die Auffassung, daß die Olivinknollen der Basalte Reste von assimilierten Peridotiten sind. die dem basaltischen primären Magma zugefügt werden. Dadurch wird ein Hinweis auf den Ort der Bildung der basaltischen Magmen gegeben.  相似文献   

Microbiota of Salt Lakes as Food for the Brine Shrimp Artemia     

Gilbert VAN STAPPEN  Thanh Toi HUYNH  Nguyen Van Ho  SUI Liying  DENG Yuangao  Peter BOSSIER 《《地质学报》英文版》2014,88(Z1):105-105

正The brine shrimp Artemia is often abundantly found in hypersaline environments.The larvae(‘nauplii’)hatching from its dormant embryos(‘cysts’)are a crucial live food item for the larval stages of fish and shrimp in aquaculture  相似文献   

Review of solutions for 3D hydrodynamic modeling applied to aquaculture in South Pacific atoll lagoons   总被引：1，自引：0，他引：1  

Andréfouët S  Ouillon S  Brinkman R  Falter J  Douillet P  Wolk F  Smith R  Garen P  Martinez E  Laurent V  Lo C  Remoissenet G  Scourzic B  Gilbert A  Deleersnijder E  Steinberg C  Choukroun S  Buestel D 《Marine pollution bulletin》2006,52(10):1138-1155

A workshop organized in French Polynesia in November 2004 allowed reviewing the current methods to model the three-dimensional hydrodynamic circulation in semi-enclosed atoll lagoons for aquaculture applications. Mollusk (e.g. pearl oyster, clam) aquaculture is a major source of income for South Pacific countries such as French Polynesia or Cook Islands. This aquaculture now requires a better understanding of circulation patterns to improve the spatial use of the lagoons, especially to define the best area to set larvae collectors. The pelagic larval duration of the relevant species (<20 days) and the size of the semi-closed lagoons (few hundreds of km2) drive the specifications of the model in terms of the spatial and temporal scale. It is considered that, in contrast with fish, mollusk larvae movements are limited and that their cycle occurs completely in the lagoon, without an oceanic stage. Atolls where aquaculture is productive are generally well-bounded, or semi-closed, without significant large and deep openings to the ocean. Nevertheless part of the lagoon circulation is driven by oceanic water inputs through the rim, ocean swells, tides and winds. Therefore, boundary conditions of the lagoon system are defined by the spatial structure of a very shallow rim (exposition and number of hoas), the deep ocean swell climate, tides and wind regimes. To obtain a realistic 3D numerical model of lagoon circulation with adequate forcing, it is thus necessary to connect in an interdisciplinary way a variety of methods (models, remote sensing and in situ data collection) to accurately represent the different components of the lagoon system and its specific boundary conditions. We review here the current methods and tools used to address these different components for a hypothetical atoll of the Tuamotu Archipelago (French Polynesia), representative of the semi-closed lagoons of the South Pacific Ocean. We hope this paper will serve as a guide for similar studies elsewhere and we provide guidelines in terms of costs for all the different stages involved.  相似文献