HR: 1340h
AN: V33B-1394    [Abstracts]
TI: A Revised Geochemical Grouping of Gondwana LIP: Distinctive Sources and Processes at the Weddell and Limpopo Triple Junctions
AU: * Luttinen, A V
EM: arto.luttinen@helsinki.fi
AF: University of Helsinki, Departent of Geology Gustaf Hallstrominkatu 2, Helsinki, 00014, Finland
AU: Leat, P T
EM: ptle@bas.ac.uk
AF: British Antarctic Survey, High Cross Madingley Road, Cambridge, CB3 0ET, United Kingdom
AB: The magma types belonging to the Gondwana large igneous province can be divided into two categories based on, respectively, their primitive mantle-like and fractionated Sm/Yb and Sr/Zr values, different Sr and Nd isotopic trends, and geographic affinity to the Weddell and Limpopo triple junctions. In the new grouping, the Ferrar magmas, the Karoo Central Area magmas, and the Kirwanveggen-Sembberget magmas from Dronning Maud Land are viewed as three major magmatic lineages generated at the Weddell triple junction. These Weddell group magmas were produced by voluminous low-pressure partial melting of possibly subduction-modified upper mantle and tended to be laterally transported over long distances. The Limpopo group magmas include the Karoo high-Ti magma types and various low-Ti types from Lebombo (Karoo), Vestfjella, and Heimefrontfjella (Dronning Maud Land). They are likely to represent magmas that were produced at high pressure from an eclogite-bearing mantle source below the Kaapvaal craton. The distribution of the Limpopo group magmas was mainly confined within the rift valleys of the Limpopo triple junction. The chemically distinctive magma types of the Gondwana LIP probably reflect heterogeneities in the Weddell and Limpopo magma sources and lithospheric level differentiation within Archean (Limpopo group) and younger lithospheric terranes.
DE: 1025 Composition of the mantle
DE: 1037 Magma genesis and partial melting (3619)
DE: 1065 Major and trace element geochemistry
DE: 5480 Volcanism (6063, 8148, 8450)
DE: 8137 Hotspots, large igneous provinces, and flood basalt volcanism
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting