Sökning: "crustal growth"

Hittade 3 uppsatser innehållade orden crustal growth.

  1. 1. U-Pb, O and Lu-Hf isotope ratios of detrital zircon from Ghana, West-African Craton : formation of juvenile, Palaeoproterozoic crust

    Master-uppsats, Lunds universitet/Geologiska institutionen

    Författare :Bára Dröfn Kristinsdóttir; [2013]
    Nyckelord :Hf-Model ages; West African Craton; detrital zircon; Ghana; crustal growth; Earth and Environmental Sciences;

    Sammanfattning : Detrital zircon were sampled from five rivers in Ghana and they were analysed in situ for U-Th-Pb, O and Lu-Hf isotopes. Based on the analyses, their U-Pb crystallisation ages, δ18O isotope ratio, εHf and Hf-model ages were determined. This provides information about the origin and crustal evolution of the Palaeoproterozoic bedrock in Ghana. LÄS MER

  3. 2. Disintegration and Devolatilisation of Sandstone Xenolith in Magmatic Conduits: an Experimental Approach

    Kandidat-uppsats, Berggrundsgeologi

    Författare :Sylvia Berg; [2010]
    Nyckelord :xenolith; melting; bubbles; gas migration; crustal volatiles; magma-crust interaction; magma volatile budget; explosive eruption;

    Sammanfattning : Xenoliths preserve evidence of magma-crust interactions in magmatic reservoirs and conduits. They reveal processes of partial melting of country rock, and disintegration into magma. Widespread evidence for frothy xenoliths in volcanic deposits exists, and these evidently indicate processes of gas liberation, bubble nucleation and bubble growth. LÄS MER

  4. 3. Zircon U-Pb, Hf and O isotope constraints on the growth versus recycling of continental crust in the Grenville orogen, Ohio, USA

    Master-uppsats, Lunds universitet/Geologiska institutionen

    Författare :Andreas Petersson; [2010]
    Nyckelord :zircon; U-Pb; geochronology; Hf-isotopes; O-isotopes; Grenville; crustal growth; North-American craton; zirkon; Hf-isotoper; O-isotopeer; kontinenttillväxt; nordamerikanska kratonen; Earth and Environmental Sciences;

    Sammanfattning : Detta arbetet har hanterat sex olika borrkärnor från den Prekambriska berggrunden i Ohio, USA. Denna berggrund är täckt med 800 – 5000 meter av Paleozoiska avlagringar och på grund av detta vet vi väldigt lite om den. LÄS MER