Search for dissertations about: "mantle plume"

Found 5 swedish dissertations containing the words mantle plume.

  1. 1. U-Pb baddeleyite geochronology of Precambrian mafic dyke swarms and complexes in southern Africa - regional scale extensional events and the origin of the Bushveld Complex

    Author : Johan Olsson; Berggrundsgeologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; U-Pb TIMS geochronology; geochemistry; baddeleyite; mafic dyke swarms; mantle plume; Bushveld Complex; Kaapvaal Craton; Zimbabwe Craton; Archean; Proterozoic;

    Abstract : Dolerite dykes are formed when iron- and magnesium-rich (mafic) mantle-derived magmas ascend through the lithosphere (upper part of the mantle) and crystallize as ‘hydro-fractures’ within the crust. Dykes may exist in great numbers to form dyke swarms (linear or radiating), which can be linked to time periods of continental break-up, or attempted break-up events, associated with voluminous volcanism. READ MORE

  2. 2. New constraints on paleoreconstructions through geochronology of mafic dyke swarms in North Atlantic Craton

    Author : Mimmi Nilsson; Berggrundsgeologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; baddeleyit; U-Pb; geokronologi; large igneous province; mantelplym; superkontinent; paleorekonstruktion; North Atlantic craton; baddeleyite; Large Igneous Province; Mantle plume; supercontinent; paleoreconstruction; U-Pb; geochronology; North Atlantic craton;

    Abstract : Earth history is punctuated by a series of events of supercontinent amalgamation and break-up. Fragments of old continents display rifted margins and orogenic sutures that testify their involvement in supercontinent cycles. READ MORE

  3. 3. Magmatism in the Cenozoic Ethiopian rift zone : the case against the Afar plume hypothesis

    Author : Begashaw Wolde; Luleå tekniska universitet; []
    Keywords : NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Applied Geology; Tillämpad geologi;

    Abstract : Volcanism and rifting in the Afro-Arabian, i.e. Red Sea - Gulf of Aden - Ethiopian, region have often been attributed to a Tertiary plume centered on Afar, at the junction of the three rifts. READ MORE

  4. 4. Evolution of continental crust in the Proterozoic : growth and reworking in orogenic systems

    Author : Andreas Petersson; Berggrundsgeologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; crustal reworking; Proterozoic; O-isotopes; Lu–Hf; U–Pb; zircon; Crustal growth;

    Abstract : To understand the growth of continental crust, the balance between juvenile mantle derived extraction, infracrustal reworking and crustal recycling, needs to be estimated. Since the beginning of the century, the use of coupled in situ zircon U–Pb, Lu–Hf and O isotope analyses as a tool to address these questions have increased exponentially. READ MORE

  5. 5. Tectonic setting and metallogeny of the Kiruna greenstones

    Author : Olof Martinsson; Luleå tekniska universitet; []
    Keywords : NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Ore Geology; Malmgeologi;

    Abstract : The Paleoproterozoic Kiruna Greenstones belong to a large c. 2.1 Ga tholeiitic province in the north-eastern part of the Baltic Shield. The mainly basaltic volcanism was related to an event of continental rifting, which ended up with continental rupture. READ MORE