Petrography, microprobe analyses and isotope composition of ultramafic rock from the northern Haskard Highlands, Shackleton Range, East Antarctica
In the Shackleton Range of East Antarctica, garnet-bearing ultramafic rocks occur as lenses in supracrustal high-grade gneisses. In the presence of olivine, garnet is an unmistakable indicator of eclogite facies metamorphic conditions. The eclogite facies assemblages are only present in ultramafic r...
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ftpangaea:oai:pangaea.de:doi:10.1594/PANGAEA.849763 2024-09-15T17:43:50+00:00 Petrography, microprobe analyses and isotope composition of ultramafic rock from the northern Haskard Highlands, Shackleton Range, East Antarctica Romer, T Mezger, Klaus Schmädicke, Esther LATITUDE: -80.410000 * LONGITUDE: -29.780000 2009 application/zip, 3 datasets https://doi.pangaea.de/10.1594/PANGAEA.849763 https://doi.org/10.1594/PANGAEA.849763 en eng PANGAEA https://doi.pangaea.de/10.1594/PANGAEA.849763 https://doi.org/10.1594/PANGAEA.849763 CC-BY-3.0: Creative Commons Attribution 3.0 Unported Access constraints: unrestricted info:eu-repo/semantics/openAccess Supplement to: Romer, T; Mezger, Klaus; Schmädicke, Esther (2009): Pan-African eclogite facies metamorphism of ultramafic rocks in the Shackleton Range, Antarctica. Journal of Metamorphic Geology, 27(5), 335-347, https://doi.org/10.1111/j.1525-1314.2009.00820.x Haskard_Highlands_N Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas ROCK Rock sample Shackleton Range Antarctica SPP1158 dataset publication series 2009 ftpangaea https://doi.org/10.1594/PANGAEA.84976310.1111/j.1525-1314.2009.00820.x 2024-07-24T02:31:21Z In the Shackleton Range of East Antarctica, garnet-bearing ultramafic rocks occur as lenses in supracrustal high-grade gneisses. In the presence of olivine, garnet is an unmistakable indicator of eclogite facies metamorphic conditions. The eclogite facies assemblages are only present in ultramafic rocks, particularly in pyroxenites, whereas other lithologies - including metabasites - lack such assemblages. We conclude that under high-temperature conditions, pyroxenites preserve high-pressure assemblages better than isofacial metabasites, provided the pressure is high enough to stabilize garnet-olivine assemblages (i.e. >=18-20 kbar). The Shackleton Range ultramafic rocks experienced a clockwise P-T path and peak conditions of 800-850 °C and 23-25 kbar. These conditions correspond to ~70 km depth of burial and a metamorphic gradient of 11-12 °C/km that is typical of a convergent plate-margin setting. The age of metamorphism is defined by two garnet-whole-rock Sm-Nd isochrons that give ages of 525 ± 5 and 520 ± 14 Ma corresponding to the time of the Pan-African orogeny. These results are evidence of a Pan-African suture zone within the northern Shackleton Range. This suture marks the site of a palaeo-subduction zone that likely continues to the Herbert Mountains, where ophiolitic rocks of Neoproterozoic age testify to an ocean basin that was closed during Pan-African collision. The garnet-bearing ultramafic rocks in the Shackleton Range are the first known example of eclogite facies metamorphism in Antarctica that is related to the collision of East and West Gondwana and the first example of Pan-African eclogite facies ultramafic rocks worldwide. Eclogites in the Lanterman Range of the Transantarctic Mountains formed during subduction of the palaeo-Pacific beneath the East Antarctic craton. Other/Unknown Material Antarc* Antarctic Antarctica Antarctica Journal East Antarctica Sea ice PANGAEA - Data Publisher for Earth & Environmental Science ENVELOPE(-29.780000,-29.780000,-80.410000,-80.410000) |
institution |
Open Polar |
collection |
PANGAEA - Data Publisher for Earth & Environmental Science |
op_collection_id |
ftpangaea |
language |
English |
topic |
Haskard_Highlands_N Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas ROCK Rock sample Shackleton Range Antarctica SPP1158 |
spellingShingle |
Haskard_Highlands_N Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas ROCK Rock sample Shackleton Range Antarctica SPP1158 Romer, T Mezger, Klaus Schmädicke, Esther Petrography, microprobe analyses and isotope composition of ultramafic rock from the northern Haskard Highlands, Shackleton Range, East Antarctica |
topic_facet |
Haskard_Highlands_N Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas ROCK Rock sample Shackleton Range Antarctica SPP1158 |
description |
In the Shackleton Range of East Antarctica, garnet-bearing ultramafic rocks occur as lenses in supracrustal high-grade gneisses. In the presence of olivine, garnet is an unmistakable indicator of eclogite facies metamorphic conditions. The eclogite facies assemblages are only present in ultramafic rocks, particularly in pyroxenites, whereas other lithologies - including metabasites - lack such assemblages. We conclude that under high-temperature conditions, pyroxenites preserve high-pressure assemblages better than isofacial metabasites, provided the pressure is high enough to stabilize garnet-olivine assemblages (i.e. >=18-20 kbar). The Shackleton Range ultramafic rocks experienced a clockwise P-T path and peak conditions of 800-850 °C and 23-25 kbar. These conditions correspond to ~70 km depth of burial and a metamorphic gradient of 11-12 °C/km that is typical of a convergent plate-margin setting. The age of metamorphism is defined by two garnet-whole-rock Sm-Nd isochrons that give ages of 525 ± 5 and 520 ± 14 Ma corresponding to the time of the Pan-African orogeny. These results are evidence of a Pan-African suture zone within the northern Shackleton Range. This suture marks the site of a palaeo-subduction zone that likely continues to the Herbert Mountains, where ophiolitic rocks of Neoproterozoic age testify to an ocean basin that was closed during Pan-African collision. The garnet-bearing ultramafic rocks in the Shackleton Range are the first known example of eclogite facies metamorphism in Antarctica that is related to the collision of East and West Gondwana and the first example of Pan-African eclogite facies ultramafic rocks worldwide. Eclogites in the Lanterman Range of the Transantarctic Mountains formed during subduction of the palaeo-Pacific beneath the East Antarctic craton. |
format |
Other/Unknown Material |
author |
Romer, T Mezger, Klaus Schmädicke, Esther |
author_facet |
Romer, T Mezger, Klaus Schmädicke, Esther |
author_sort |
Romer, T |
title |
Petrography, microprobe analyses and isotope composition of ultramafic rock from the northern Haskard Highlands, Shackleton Range, East Antarctica |
title_short |
Petrography, microprobe analyses and isotope composition of ultramafic rock from the northern Haskard Highlands, Shackleton Range, East Antarctica |
title_full |
Petrography, microprobe analyses and isotope composition of ultramafic rock from the northern Haskard Highlands, Shackleton Range, East Antarctica |
title_fullStr |
Petrography, microprobe analyses and isotope composition of ultramafic rock from the northern Haskard Highlands, Shackleton Range, East Antarctica |
title_full_unstemmed |
Petrography, microprobe analyses and isotope composition of ultramafic rock from the northern Haskard Highlands, Shackleton Range, East Antarctica |
title_sort |
petrography, microprobe analyses and isotope composition of ultramafic rock from the northern haskard highlands, shackleton range, east antarctica |
publisher |
PANGAEA |
publishDate |
2009 |
url |
https://doi.pangaea.de/10.1594/PANGAEA.849763 https://doi.org/10.1594/PANGAEA.849763 |
op_coverage |
LATITUDE: -80.410000 * LONGITUDE: -29.780000 |
long_lat |
ENVELOPE(-29.780000,-29.780000,-80.410000,-80.410000) |
genre |
Antarc* Antarctic Antarctica Antarctica Journal East Antarctica Sea ice |
genre_facet |
Antarc* Antarctic Antarctica Antarctica Journal East Antarctica Sea ice |
op_source |
Supplement to: Romer, T; Mezger, Klaus; Schmädicke, Esther (2009): Pan-African eclogite facies metamorphism of ultramafic rocks in the Shackleton Range, Antarctica. Journal of Metamorphic Geology, 27(5), 335-347, https://doi.org/10.1111/j.1525-1314.2009.00820.x |
op_relation |
https://doi.pangaea.de/10.1594/PANGAEA.849763 https://doi.org/10.1594/PANGAEA.849763 |
op_rights |
CC-BY-3.0: Creative Commons Attribution 3.0 Unported Access constraints: unrestricted info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1594/PANGAEA.84976310.1111/j.1525-1314.2009.00820.x |
_version_ |
1810491035962310656 |