Tectono-metamorphic history of the re-worked, high-grade Maud Belt at central-Eastern H.U. Sverdrupfjella, Antarctica
The reworking of granulites by amphibolite- to granulite-facies metamorphism can complicate the interpretation of their geological history because the event that reached higher peak P-T conditions will either completely overprint earlier peak assemblages or prevent the formation of new 'peak...
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ftunivcapetownir:oai:open.uct.ac.za:11427/16195 2024-09-15T17:45:11+00:00 Tectono-metamorphic history of the re-worked, high-grade Maud Belt at central-Eastern H.U. Sverdrupfjella, Antarctica Byrnes, Gregory Diener, Johann Fagereng, Ake 2015 application/pdf http://hdl.handle.net/11427/16195 eng eng Department of Geological Sciences Faculty of Science University of Cape Town http://hdl.handle.net/11427/16195 Geological Sciences Master Thesis Masters MSc 2015 ftunivcapetownir 2024-06-25T03:27:02Z The reworking of granulites by amphibolite- to granulite-facies metamorphism can complicate the interpretation of their geological history because the event that reached higher peak P-T conditions will either completely overprint earlier peak assemblages or prevent the formation of new 'peak' minerals. The extent of reworking in granulites is controlled by three main factors, namely: (1) the pressures and temperatures reached in earlier and later metamorphic events, (2) the extent of deformation during subsequent events, and (3) the amount of fluid influx into the system during subsequent metamorphic events. Extensive reworking will occur if the peak temperature of the later event exceeds that of the earlier event, but if it does not, reworking will be less pervasive, and restricted to areas of deformation and/or fluid influx. The Salknappen nunatak in central-Eastern H.U. Sverdrupfjella, Antarctica forms a part of the highgrade Maud Belt that was formed by a granulite facies Grenvillian orogeny and was variably overprinted by high-grade metamorphism (eclogite to amphibolite facies) during the PanAfrican orogeny. The degree of reworking during the Pan-African has been a contentious issue for some time, with early workers assigning the metamorphic peak to the Grenvillian, whereas others assigned it to the Pan-African. Mineral assemblages and textures preserved in metapelitic and metamafic rocks preserve evidence of only one prograde to retrograde metamorphic cycle with peak mineral assemblages that are characteristic of granulites. Sillimanite in metapelitic rocks forms pseudomorphs after kyanite whereas garnet breakdown microstructures and in both metapelitic and metamafic rocks formed as a result of near-isothermal decompression. Garnet and hornblende display retrograde zoning profiles whereas retrograde cummingtonite, hornblende, plagioclase and ilmenite in metamafic rocks moderately constrain retrograde conditions. Pseudosection modelling with THERMOCALC on peak mineral assemblages from metapelitic and ... Master Thesis Antarc* Antarctica University of Cape Town: OpenUCT |
institution |
Open Polar |
collection |
University of Cape Town: OpenUCT |
op_collection_id |
ftunivcapetownir |
language |
English |
topic |
Geological Sciences |
spellingShingle |
Geological Sciences Byrnes, Gregory Tectono-metamorphic history of the re-worked, high-grade Maud Belt at central-Eastern H.U. Sverdrupfjella, Antarctica |
topic_facet |
Geological Sciences |
description |
The reworking of granulites by amphibolite- to granulite-facies metamorphism can complicate the interpretation of their geological history because the event that reached higher peak P-T conditions will either completely overprint earlier peak assemblages or prevent the formation of new 'peak' minerals. The extent of reworking in granulites is controlled by three main factors, namely: (1) the pressures and temperatures reached in earlier and later metamorphic events, (2) the extent of deformation during subsequent events, and (3) the amount of fluid influx into the system during subsequent metamorphic events. Extensive reworking will occur if the peak temperature of the later event exceeds that of the earlier event, but if it does not, reworking will be less pervasive, and restricted to areas of deformation and/or fluid influx. The Salknappen nunatak in central-Eastern H.U. Sverdrupfjella, Antarctica forms a part of the highgrade Maud Belt that was formed by a granulite facies Grenvillian orogeny and was variably overprinted by high-grade metamorphism (eclogite to amphibolite facies) during the PanAfrican orogeny. The degree of reworking during the Pan-African has been a contentious issue for some time, with early workers assigning the metamorphic peak to the Grenvillian, whereas others assigned it to the Pan-African. Mineral assemblages and textures preserved in metapelitic and metamafic rocks preserve evidence of only one prograde to retrograde metamorphic cycle with peak mineral assemblages that are characteristic of granulites. Sillimanite in metapelitic rocks forms pseudomorphs after kyanite whereas garnet breakdown microstructures and in both metapelitic and metamafic rocks formed as a result of near-isothermal decompression. Garnet and hornblende display retrograde zoning profiles whereas retrograde cummingtonite, hornblende, plagioclase and ilmenite in metamafic rocks moderately constrain retrograde conditions. Pseudosection modelling with THERMOCALC on peak mineral assemblages from metapelitic and ... |
author2 |
Diener, Johann Fagereng, Ake |
format |
Master Thesis |
author |
Byrnes, Gregory |
author_facet |
Byrnes, Gregory |
author_sort |
Byrnes, Gregory |
title |
Tectono-metamorphic history of the re-worked, high-grade Maud Belt at central-Eastern H.U. Sverdrupfjella, Antarctica |
title_short |
Tectono-metamorphic history of the re-worked, high-grade Maud Belt at central-Eastern H.U. Sverdrupfjella, Antarctica |
title_full |
Tectono-metamorphic history of the re-worked, high-grade Maud Belt at central-Eastern H.U. Sverdrupfjella, Antarctica |
title_fullStr |
Tectono-metamorphic history of the re-worked, high-grade Maud Belt at central-Eastern H.U. Sverdrupfjella, Antarctica |
title_full_unstemmed |
Tectono-metamorphic history of the re-worked, high-grade Maud Belt at central-Eastern H.U. Sverdrupfjella, Antarctica |
title_sort |
tectono-metamorphic history of the re-worked, high-grade maud belt at central-eastern h.u. sverdrupfjella, antarctica |
publisher |
Department of Geological Sciences |
publishDate |
2015 |
url |
http://hdl.handle.net/11427/16195 |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_relation |
http://hdl.handle.net/11427/16195 |
_version_ |
1810492916809859072 |