granite-lamprophyre genetic link
Summary The central Victoria Land crustal sector of the early Paleozoic Ross Orogen is characterized by the widespread occurrence of pink granite plutons and dikes (Irizar unit) and lamprophyric dikes (Vegetation unit). Structural evidence indicates these intrusions were emplaced in a tensional regi...
| Main Authors: | , , , |
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.555.7013 http://pubs.usgs.gov/of/2007/1047/ea/of2007-1047ea002.pdf |
| Summary: | Summary The central Victoria Land crustal sector of the early Paleozoic Ross Orogen is characterized by the widespread occurrence of pink granite plutons and dikes (Irizar unit) and lamprophyric dikes (Vegetation unit). Structural evidence indicates these intrusions were emplaced in a tensional regime during late stages of the Ross Orogeny. Geochronological U-Pb and 40Ar-39Ar data indicate emplacement age for both units within a restricted time interval around 490 Ma. This, coupled with emplacement style, imply a fast, block-like exhumation during this postcollisional stage. The Irizar granites-dikes and the Vegetation lamprophyres are both potassic, with overlapping initial Sr-Nd isotope ratios. The Vegetation melts derived from enriched subcontinental lithospheric mantle further metasomatised by a Ross subduction component, while the Irizar melts derived from remelting of Vegetation-like underplated material. Comparison with coeval postcollisional igneous activity in Australia-Tasmania suggests similar scenarios with slab roll-back in the Antarctic sector evolving to slab break-up in Australia-Tasmania. |
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