ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 1
    Description / Table of Contents: The continental crust is our archive of Earth history, and the store of many natural resources; however, many key questions about its formation and evolution remain debated and unresolved: - What processes are involved in the formation, differentiation and evolution of continental crust, and how have these changed throughout Earth history? - How are plate tectonics, the supercontinent cycle and mantle cooling linked with crustal evolution? - What are the rates of generation and destruction of the continental crust through time? - How representative is the preserved geological record? A range of approaches are used to address these questions, including field-based studies, petrology and geochemistry, geophysical methods, palaeomagnetism, whole-rock and accessory-phase isotope chemistry and geochronology. Case studies range from the Eoarchaean to Phanerozoic, and cover many different cratons and orogenic belts from across the continents.
    Pages: Online-Ressource (362 Seiten)
    ISBN: 9781862393752
    Language: English
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillian Magazines Ltd.
    Nature 423 (2003), S. 858-861 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Komatiites are ultramafic volcanic rocks containing more than 18 per cent MgO (ref. 1) that erupted mainly in the Archaean era (more than 2.5 gigayears ago). Although such compositions occur in later periods of Earth history (for example, the Cretaceous komatiites of Gorgona Island), ...
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A major difficulty with determining the petrogenetic history of mantle eclogites is the lack of definitive age constraints, owing to their complex history1'2'4. Here we use the Re-Os isotope system to determine the age of a well-characterized suite of eclogites from the Udachnaya ...
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 359 (1992), S. 718-721 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Picrite basalts from the Karoo flood basalt province have been the subject of extensive geochemical study8"10, in part because they are considered to represent primitive magmas similar to parental liquids that evolve to form the abundant, tholeiitic basalts typical of this and other flood basalt ...
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The Re — Os isotopic systematics of komatiites and spatially associated basalts from Gorgona Island, Colombia, indicate that they were produced at 155±43 Ma. Subsequent episodes of volcanism produced basalts at 88.1±3.8 Ma and picritic and basaltic lavas at ca. 58 Ma. The age for the ultramafic rocks is important because it coincides with the late-Jurassic, early-Cretaceous disassembly of Pangea, when the North- and South-American plates began to pull apart. Deep-seated mantle upwelling possibly precipitated the break-up of these continental plates and caused a tear in the subducting slab west of Gorgona, providing a rare, late-Phanerozoic conduit for the komatiitic melts. Mantle sources for the komatiites were heterogeneous with respect to Os and Pb isotopic compositions, but had homogeneous Nd isotopic compositions (εNd+9±1). Initial 187Os/186Os normalized to carbonaceous chondrites at 155 Ma (γOs) ranged from 0 to +22, and model-initial μ values ranged from 8.17 to 8.39. The excess radiogenic Os, compared with an assumed bulk-mantle evolution similar to carbonaceous chondrites, was likely produced in portions of the mantle with long-term elevated Re concentrations. The Os, Pb and Nd isotopic compositions, together with major-element constraints, suggest that the sources of the komatiites were enriched more than 1 Ga ago by low (〈20%) and variable amounts of a basalt or komatiite component. This component was added as either subducted oceanic crust or melt derived from greater depths in the mantle. These results suggest that the Re — Os isotope system may be a highly sensitive indicator of the presence of ancient subducted oceanic crust in mantle-source regions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Publication Date: 2019-07-16
    Description: It has been more than two decades since White (1985) and Zindler and Hart (1986) proposed that the observed range of Sr-Nd-Pb isotope ratios of oceanic basalts can be described as mixtures of depleted mantle (DMM) with a limited number of enriched global endmember components (HIMU, EMI, EMII). There is no doubt that the global endmembers in isotope space represent extremes of the timing and magnitude of chemical fractionation processes in the Earths mantle. However, it remains a matter of debate how the intermediate isotopic compositions often evident on the local scale of individual islands are formed: (1) Do they represent mixtures between the limited number of global endmembers, or (2) do they reflect processes intermediate to the ones forming the global endmembers, or (3) does each individual ocean island basalt suite provide us with information about the timing and kind of geochemical differentiation forming that single source? Each possibility has important geodynamic implications. The Earths mantle is continuously differentiating through partial melting and remixing through plate tectonic recycling and convection, suggesting variable timing and composition of mantle sources. However, mantle sources might be formed by mixed lithologies and thus melt compositions might reflect mixtures of sources of more extreme compositions, possibly representing the global endmembers. We further address these questions based on two examples. Grande Comore Island is located on 140 Ma Indian Ocean lithosphere and its lavas reflect plume-lithosphere interaction. The Grande Comore plume component has Sr-Nd-Pb isotopic compositions intermediate between HIMU and EMI. Its extreme Os isotope ratios are among the highest measured in shield building-stage lavas of oceanic islands, giving further support for generally radiogenic Os isotope ratios in the EMI and HIMU compositions. A lack of correlation between OIB with high Os isotope ratios with inferred lithospheric thickness implies that they are not solely controlled by melt dynamics of a pyroxenite-peridotite source, but require variable proportions of pyroxenite in individual sources. New isotope data from the second example, the Discovery Seamounts in the South Atlantic, reveal a continuum in compositions between the extreme EMI composition of Walvis Ridge DSDP 525A and the LOMU extreme of the Discovery ridge anomaly (Douglass et al., 1999) and require a range of extreme composition outside the mixing tetrahedron of the global endmembers. In the global context, each individual island or volcano with enriched mantle affinity seems to form a trend towards its own unique enriched mantle endmember, inconsistent with mixing between narrowly defined global endmembers. The spectrum of enriched mantle endmembers is consistent with a dynamic Earth, continuously recycling varying proportions of oceanic crust, sediment and some continental lower crust or mantle. Douglass, J., Schilling, J.-G. and Fontignie, D., 1999. J. Geophys. Res., 104: 2941-2962.White, W.M., 1985. Geology, 13: 115-118.Zindler, A. and Hart, S., 1986. Ann. Rev. Earth Planet. Sci., 14: 493-571.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 1989-07-01
    Print ISSN: 0022-1376
    Electronic ISSN: 1537-5269
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Publication Date: 2013-02-15
    Print ISSN: 1529-6466
    Electronic ISSN: 1943-2666
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2015-12-15
    Print ISSN: 1529-6466
    Electronic ISSN: 1943-2666
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2019
    Description: 〈p〉Neoproterozoic West African diamonds contain sulfide inclusions with mass-independently fractionated (MIF) sulfur isotopes that trace Archean surficial signatures into the mantle. Two episodes of subduction are recorded in these West African sulfide inclusions: thickening of the continental lithosphere through horizontal processes around 3 billion years ago and reworking and diamond growth around 650 million years ago. We find that the sulfur isotope record in worldwide diamond inclusions is consistent with changes in tectonic processes that formed the continental lithosphere in the Archean. Slave craton diamonds that formed 3.5 billion years ago do not contain any MIF sulfur. Younger diamonds from the Kaapvaal, Zimbabwe, and West African cratons do contain MIF sulfur, which suggests craton construction by advective thickening of mantle lithosphere through conventional subduction-style horizontal tectonics.〈/p〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...