Petrology and Geochronology of Granulites from the McKaskle Hills, Eastern Amery Ice Shelf, Antarctica, and Implications for the Evolution
A combined petrological and geochronological study was carried out on mafic granulites and associated felsic gneisses from the McKaskle Hills, eastern Amery Ice Shelf, East Antarctica. Garnet-bearing mafic granulites exhibit reaction textures and exsolution textures that indicate two-stage metamorph...
| Main Authors: | , , , , |
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| Other Authors: | |
| Format: | Text |
| Language: | English |
| Published: |
2006
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| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.630.692 http://petrology.oxfordjournals.org/content/48/8/1443.full.pdf |
| Summary: | A combined petrological and geochronological study was carried out on mafic granulites and associated felsic gneisses from the McKaskle Hills, eastern Amery Ice Shelf, East Antarctica. Garnet-bearing mafic granulites exhibit reaction textures and exsolution textures that indicate two-stage metamorphic evolution. Thermobarometric estimates from matrix and symplectite assemblages yield peak and retrograde P^T conditions of 90^95 kbar and 880^9508C and 66^72 kbar and 700^7508C, respectively. Similar but slightly scattered peak P^Testimates of 79^101kbar and 820^9808C are obtained from the core compositions of minerals from felsic para-and orthogneisses. Evidence for the prograde history is provided by muscovite inclusions in garnet from a paragneiss. Sensitive high-resolution ion microprobe U^Pb zircon dating reveals an evolution-ary history for the granulites, including a mafic and felsic igneous intrusion at 1174^1019Ma, sedimentation after 932^916Ma, and |
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