ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    On the age of the Onverwacht Group, Swaziland sequence, South Africa (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Some rocks of the Onverwacht Group, South Africa, have been analyzed for Rb and Sr concentrations and Sr isotopic composition. These rocks include volcanic rocks, layered ultramafic differentiates and cherty sediments. Whole rock data indicate that the Rb-Sr isotopic systems in many samples were open and yield no reasonable isochron relationships. However, the data of mineral separates from a basaltic komatiite define a good isochron of 3.50 (plus or minus .2) b.y. with an initial Sr-87/Sr-86 ratio of 0.70048 plus or minus 5. The orthodox interpretation of this age is the time of the low grade metamorphism. It is reasonable to assume that the age of 3.50 b.y. might also represent the time of initial Onverwacht volcanism and deposition. The initial Sr-87/Sr-86 ratio obtained above is important to an understanding of the Sr isotopic composition of the Archean upper mantle.
    Keywords: GEOPHYSICS
    Type: Geochimica et Cosmochimica Acta; 38; June 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    Mesozoic thermal events in southeast China (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: A new set of age data on some granitic batholiths of southeast China is reported. It is shown that these new data support the postulate of Larsen and Putman (1972) that, during the late Mesozoic, the Pacific sea floor was spreading from at least five spreading centers joined at two triple points. Attention is called to the coeval occurrence of paired metamorphism and intrusion on both sides of the Pacific during the Mesozoic.
    Keywords: GEOPHYSICS
    Type: Nature; 248; Apr. 5
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Significance of the Sm-Nd isotopic systematics of the Akilia Association (1986)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Samarium-Neodymium analyses were carried out on fourteen samples of basic to ultrabasic metavolcanics from several enclaves of the Amitsoq gneisses (T = to or approximately 3,700 Ma). Field observations suggest that all the analyzed rocks belong to the pre-Amitsoq Akilia Association. Consequently, a minimum age of 3,700 Ma is postulated for the emplacement of their protoliths. When all the data points are put together in a conventional isochron diagram, no clear isochron relationship can be discerned. However, the points seem to fall within a band broadly corresponding to an age of 3,600 Ma. The isotopic results are difficult to interpret satisfactorily. Two contrasting interpretations are offered and summarized: (1) data scatter as a result of open system behavior; and (2) data scatter due to a melange of data sets defining two distinct isochrons.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst. Workshop on Early Crustal Genesis: The World's Oldest Rocks; p 55-58
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    Rb-Sr ages of the Archean rocks from the Vermilion district, northeastern Minnesota (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The Vermilion district in Northeastern Minnesota is a classic example of a lower Precambrian greenstone-granite terrane in the Superior Province of the Canadian Shield. The present study presents new Rb-Sr isotopic data for the Ely Greenstone, the Newton Lake Formation, granitic pebbles that occur within the Ely Greenstone, a graywacke composite of the Knife Lake Group, and some Algoman granites whose data are complementary to those of Peterman et al. (1972). The isochron ages obtained are statistically indistinguishable and therefore cannot be used to resolve the timing of specific geologic events. Volcanic extrusion, granitic intrusion, and metamorphism are shown to be less contemporaneous events which probably took place within a time span of less than 50 m.y. A major conclusion is that a granitic basement probably did not underlie the Ely Greenstone.
    Keywords: GEOPHYSICS
    Type: Geochimica et Cosmochimica Acta; 39; Dec. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    Trace element geochemistry of Archean volcanic rocks (1974)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The K, Rb, Sr, Ba and rare-earth-element contents of some Archean volcanic rocks from the Vermilion greenstone belt, northeast Minnesota, were determined by the isotopic dilution method. The characteristics of trace element abundances, supported by the field occurrences and major element chemistry, suggest that these volcanic rocks were formed in an ancient island arc system.
    Keywords: GEOPHYSICS
    Type: Geochimica et Cosmochimica Acta; 38; Apr. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...