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  • 1
    Electronic Resource
    Electronic Resource
    Geothermobarometry of mafic granulites and metapelite from the Palghat Gap, South India: petrological evidence for isothermal uplift and rapid cooling (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of metamorphic geology 12 (1994), S. 0 
    Details
    ISSN: 1525-1314
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The Palghat Gap region is located near the centre of the large southern Indian granulite terrane. at the northern edge of the Kodaikanal charnockite massif. The dominant rock types in the region are hornblende-biotite ± orthopyroxene gneisses and charnockites along with minor amounts of intercalated mafic granulite, metapelite and calc-silicate. The P-T estimates from garnetiferous mafic granulites and metapelite samples are generally in the range 9-10 kbar and 800-900d̀ C using both conventional thermobarometric methods and the TWEEQU thermobarometry program. These P-T estimates, which should be taken as minimum values, are among the highest yet reported for South Indian and Sri Lankan granulites. The occurrence of orthopyroxene + plagioclase symplectites around embayed garnet grains in the mafic granulites and cordierite rims around garnet grains in metapelite suggest an isothermal decompression-type path. Similarly, a core-rim P-T trajectory indicates c. 3 and 7 kbar decompression at high temperature in the mafic granulites and metapelite, respectively. In both rock types, the key to the determination of the retrograde P-T path was the recognition of small amounts of second generation plagioclase with a more anorthitic composition than the matrix plagioclase. The preservation of high garnet-pyroxene temperatures in the mafic granulites (despite small garnet grain size) suggests rapid cooling of the terrane. Calculated minimum cooling rates range from 8 to 80d̀ C Ma-1. Such cooling rates are more rapid than those associated with normal isostatic processes and suggest that the terrane was tectonically exhumed at high temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1525-1314.1994.tb00037.x
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  • 2
    Electronic Resource
    Electronic Resource
    Metamorphism at a late Mesozoic accretionary margin: a study from the Coast Belt of the North American Cordillera (2001)
    Oxford, UK : Blackwell Science Inc
    Journal of metamorphic geology 19 (2001), S. 0 
    Details
    ISSN: 1525-1314
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The late Mesozoic and Cenozoic metamorphic evolution of the western North American continental margin is recorded in a belt of homogeneous metapelitic rocks, the Kluane metamorphic assemblage (KMA), in the northern Coast Belt of Yukon Territory. A record of Late Cretaceous medium-pressure and -temperature (c. 7 kbar, 500 °C) metamorphism, M1, is preserved in Ca-rich garnet and Na-rich plagioclase cores in rocks that were little affected by later events. M1 was synchronous with mylonitization and is attributed to accretion of the KMA to the ancient continental margin. Isothermal decompression during rapid uplift was followed by early Eocene emplacement of the Ruby Range Batholith (RRB), part of a magmatic arc produced by subduction of the Kula plate. The intrusion of the RRB led to a contact metamorphic overprint, M2, producing a 5–6 km wide aureole in which the grade ranges from subgarnet zone to garnet–cordierite–K-feldspar zone. Pressure and temperature estimates for M2, calculated from mineral equilibria, are 3.5–4.5 kbar and 530–720 °C, generally consistent with the stability limits of the observed mineral assemblages. Comparison of mineral assemblages and P–T conditions in the KMA with those in the Mclaren Glacier metamorphic belt in Alaska does not support the correlation of the two metamorphic sequences. This weakens the hypothesis proposing 400 km of dextral slip along the Denali fault zone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.0263-4929.2000.00300.x
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  • 3
    Electronic Resource
    Electronic Resource
    Strategies for high-temperature oxygen isotope thermometry: a worked example from the Laramie Anorthosite Complex, Wyoming, USA
    Amsterdam : Elsevier
    Earth and Planetary Science Letters 117 (1993), S. 407-422 
    Details
    ISSN: 0012-821X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0012-821X(93)90093-O
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  • 4
    Electronic Resource
    Electronic Resource
    Fluorescence and electron microscopical study of aminergic nuclei in the brain of Bufo poweri (1974)
    Springer
    Cell & tissue research 149 (1974), S. 481-495 
    Details
    ISSN: 1432-0878
    Keywords: Brain ; Monoamines ; Amphibia ; Fluorescence microscopy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of monoamines in the brain of Bufo poweri was investigated with the Falck-Hillarp method. Green fluorescence was observed in neurons of the diencephalic preoptic recess organ (PRO) and its so-called additional cells, in the paraventricular organ (PVO) and its so-called accompanying cells, in the nucleus infundibularis dorsalis (NID) and in the mesencephalic nucleus reticularis mesencephali (NRM). Yellow fluorescence was found in some cells of the PVO and NID and in neurons of the caudal part of the NRM. Extensive tracts of aminergic fibres are described running caudo-rostrally and mainly terminating in the septa and striata of the telencephalon. It is suggested that the aminergic nuclei mentioned above partly contribute to the ascending tracts. Other fibres, originating in the PVO and NID are curving centro-caudally towards the median eminence. Although with the electron microscope some apparently aminergic nerve fibres were detected in the pars intermedia, such fibres have not been observed fluorescence microscopically. The ultrastructural study of the PRO has shown the presence of two types of aminergic liquor-contacting neurons. Among the distal cells of the PRO, aminergic and peptidergic neurons were distinguished. The presence of PRO additional cells, which are considered as a rostral extension of the PRO, is discussed with regard to the terrestrial habitat of the species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223027
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  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructural and cytochemical localization of the storage sites of monoamines in the paraventricular organ of Xenopus laevis tadpoles (1974)
    Springer
    Cell & tissue research 151 (1974), S. 417-421 
    Details
    ISSN: 1432-0878
    Keywords: Paraventricular organ ; Xenopus laevis ; Monoamines ; Cytochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultracytochemical identification of monoamines in the paraventricular organ (PVO) of Xenopus laevis tadpoles was achieved by applying glutaraldehyde-potassium dichromate fixation to the brains. It appears that the amines are concentrated inside elongated or round large granular vesicles within the neurons. The presence of dopamine and, to a lesser extent, of indolamines in neurons of the PVO is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222988
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  • 6
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    Fluorescence and electron microscopical study of aminergic nuclei in the brain of Bufo poweri (1974)
    Springer
    Details
    Publication Date: 1974-06-01
    Print ISSN: 0302-766X
    Electronic ISSN: 1432-0878
    Topics: Biology , Medicine
    Published by Springer
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  • 7
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    Ultrastructural and cytochemical localization of the storage sites of monoamines in the paraventricular organ of Xenopus laevis tadpoles (1974)
    Springer
    Details
    Publication Date: 1974-08-01
    Print ISSN: 0302-766X
    Electronic ISSN: 1432-0878
    Topics: Biology , Medicine
    Published by Springer
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  • 8
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    An experimental study of the diffusion of C and O in calcite in mixed CO2-H2O fluid (2011)
    Mineralogical Society of America
    Details
    Publication Date: 2011-08-01
    Description: The diffusivity of C and O in calcite in mixed CO2-H2O fluid was determined over the range in xCO2 from 1.0 to about 0.2 at 700 {degrees}C, 100 MPa, with selected experiments conducted at pressures to 250 MPa and temperatures of 600 and 800 {degrees}C. The diffusivity of C, DC, varies little with xCO2, although there is some evidence for a slight increase in DC from ~5 x 10-18 to ~5 x 10-17 cm2/s with decreasing xCO2. Our data and those of others are consistent with a model for DC {vprop} 1/fCO2. Despite the large uncertainty, we observed that the diffusivity of O, DO, increases from ~2 x 10-16 to ~5 x 10-14 cm2/s with xCO2 decreasing from 1.0 to 0. There is a good correlation at 700 {degrees}C between log DO and log fH2O regardless of the total pressure, matching the observations of previous workers. The data are consistent with a simple two-component model for the diffusion of O in calcite, one component for diffusion in the presence of CO2 and one in the presence of H2O: DO = DOCO2 + DOH2O aH2O. The activity of H2O is relative to the fugacity at 100 MPa, 700 {degrees}C. DOCO2 is 3.45 x 10-16, and DOH2O is 3.8 x 10-14 cm2/s. The data indicate that the rate of diffusion of C and O in calcite is controlled by reactions at the surface of calcite. Adsorption of H2O and the creation of vacancies at the surface account for the dependence of the diffusivity on the fugacity of the fluid components. There is little evidence that H itself diffuses into calcite. With this model and the values of DO in pure CO2 (Labotka et al. 2000) and in pure H2O (Farver 1994), the value of DO is predicted over the temperature range 600-800 {degrees}C and pH2O up to 300 MPa, the range of the data. Calculated closure temperatures for diffusive exchange of O between calcite and fluid are reduced by about 150 {degrees}C in the presence of an aqueous fluid.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
    Published by Mineralogical Society of America
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  • 9
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    A Record of Paleoproterozoic Subduction Preserved in the Northern Slave Cratonic Mantle: Sr-Pb-O Isotope and Trace-element Investigations of Eclogite Xenoliths from the Jericho and Muskox Kimberlites (2014)
    Oxford University Press
    Details
    Publication Date: 2014-02-09
    Description: Paleoproterozoic eclogite xenoliths from the Jericho and Muskox kimberlites located in the northern Slave craton, Canada, display geochemical and isotopic evidence of a recycled oceanic lithosphere origin. The eclogites comprise a diverse suite of kyanite- and diamond-bearing and bimineralic xenoliths that have a wide range of geochemical compositions. Calculated whole-rock eclogite compositions are broadly basaltic to picritic, ranging from 5 to 13 wt % MgO. Calculated whole-rock trace-element compositions for the eclogites show three overall REE patterns: the first pattern resembles that of oceanic gabbros with prominent positive Eu anomalies and flat heavy REE; the second pattern is similar to the first but displays marked light REE depletion that is interpreted to record partial melt loss; the third pattern lacks Eu anomalies and instead displays both gradually increasing REE contents from La to Lu similar to boninitic melts and ‘humped’ middle REE patterns similar to those observed in eclogites formed by reaction with subduction fluids. Several eclogites have garnet and/or clinopyroxene 18 O values 〉6, which coupled with the trace-element systematics of all the eclogites is interpreted to reflect derivation from recycled oceanic lithosphere protoliths. Lead isotope data for eclogite clinopyroxenes form a broad array that extends from highly radiogenic isotope compositions similar to the host Jericho kimberlite to an intersection with the Stacey–Kramers terrestrial two-stage Pb evolution curve at c . 2·2 Ga. The slope of this data array defines a secondary Pb isochron with an associated age of 1·7 ± 0·3 Ga. Although it is possible that the Pb isotope array is actually a mixing line between the eclogite protolith and the host Jericho kimberlite, both the secondary isochron age and the c . 2·2 Ga Stacey–Kramers model age are consistent with Paleoproterozoic protolith oceanic crust formation. Eclogite xenoliths and eclogitic diamond inclusions from the Slave craton almost exclusively yield c . 2 Ga ages, which are broadly compatible with formation during subduction associated with the c . 1·9–1·8 Ga Wopmay orogeny at the western margin of the Slave craton. Trends in the Sr–Pb isotopic compositions of the eclogite clinopyroxene show that seawater alteration of the oceanic crust protoliths was an important process during protolith formation, and cryptic metasomatism further increased the Pb and Sr isotope values. This metasomatism is probably associated with the Jurassic kimberlite magmatism; however, contributions from the Mesoproterozoic Mackenzie event cannot be completely excluded.
    Print ISSN: 0022-3530
    Electronic ISSN: 1460-2415
    Topics: Geosciences
    Published by Oxford University Press
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  • 10
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    Circa 2.3‐Ga Magmatism of the Arrowsmith Orogeny, Uranium City Region, Western Churchill Craton, Canada (2007)
    University of Chicago Press
    Details
    Publication Date: 2007-03-01
    Print ISSN: 0022-1376
    Electronic ISSN: 1537-5269
    Topics: Geosciences
    Published by University of Chicago Press
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