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Details van artikel 7 van 13 gevonden artikelen
| Titel: |
Geology and structure of the Larsemann Hills area, Prydz Bay, East Antarctica |
| Auteur: |
Stuwe, Kurt Braun, Hans-Martin Peer, Helmuth |
| Verschenen in: |
Australian journal of earth sciences |
| Paginering: | Jaargang 36 (1989) nr. 2 pagina's 219-241 |
| Jaar: |
1989-06 |
| Inhoud: |
The Larsemann Hills area in Prydz Bay, East Antarctica, underwent low pressure granulite facies metamorphism about 1100 Ma ago. This peak metamorphic age is similar to that of large areas west of the Larsemann Hills, but contrasts with the Archaean age of the Vestfold Hills only 100 km to the northeast. The dominant rock types in the Larsemann Hills are metapelitic cordierite- and Fe-Ti oxide-rich gneisses and various leucogneisses. Felsic, garnet-bearing, variably foliated 'yellow gneiss' (60% of outcrop) and the extremely cordierite-rich 'blue gneiss' (10% of outcrop) constitute the two major metasedimentary units. Mafic dykes, charnockites and evidence of brittle deformation are absent, and there are minor orthogneisses as well as mafic two pyroxene gneisses that lack garnet and ultramafic rocks. These features distinguish the Larsemann Hills not only from the Archaean Vestfold Hills to the northeast, but also from the 1000 Ma old 'transition zone' in the Rauer Group and outcrops of similar age to the southwest. Three major deformation phases affected the Larsemann Hills area. The first deformation, D1, took place prior to and synchronously with the peak metamorphic event M1 and formed tight, isoclinal folds which cannot be resolved on a regional scale. The second deformation, D2, the major outcrop-scale shortening deformation, took place at the time of decompression (M2) from the metamorphic peak, and subsequent minor deformation may have continued during cooling to the stable geotherm. The third deformation, D3, folded the Larsemann Hills gneisses into a large, knee-shaped fold plunging steeply to the southwest. Overprinting of many textures by large porphyroblasts and granitic melts indicates that a thermal event (M3) or rapid increase in H2O activity affected the area after the pervasive ductile deformations. This event may correlate with D3 and may have been responsible for the excavation of the Larsemann Hills during the Palaeozoic. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 7 van 13 gevonden artikelen
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