Early–Middle Jurassic dolerite dykes from western Dronning Maud Land (Antarctica): identifying mantle sources in the Karoo Large Igneous Province
A suite of dolerite dykes from the Ahlmannryggen region of western Dronning Maud Land (Antarctica) forms part of the much more extensive Karoo igneous province of southern Africa. The dyke compositions include both low- and high-Ti magma types, including picrites and ferropicrites. New 40Ar/39Ar age...
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Oxford University Press
2005
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Online Access: | http://nora.nerc.ac.uk/id/eprint/1943/ http://petrology.oxfordjournals.org/cgi/content/abstract/46/7/1489 https://doi.org/10.1093/petrology/egi023 |
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ftnerc:oai:nora.nerc.ac.uk:1943 2024-06-09T07:40:09+00:00 Early–Middle Jurassic dolerite dykes from western Dronning Maud Land (Antarctica): identifying mantle sources in the Karoo Large Igneous Province Riley, Teal R. Leat, Philip T. Curtis, Michael L. Millar, Ian L. Duncan, Robert A. Fazel, Adela 2005 http://nora.nerc.ac.uk/id/eprint/1943/ http://petrology.oxfordjournals.org/cgi/content/abstract/46/7/1489 https://doi.org/10.1093/petrology/egi023 unknown Oxford University Press Riley, Teal R. orcid:0000-0002-3333-5021 Leat, Philip T.; Curtis, Michael L.; Millar, Ian L.; Duncan, Robert A.; Fazel, Adela. 2005 Early–Middle Jurassic dolerite dykes from western Dronning Maud Land (Antarctica): identifying mantle sources in the Karoo Large Igneous Province. Journal of Petrology, 46 (7). 1489-1524. https://doi.org/10.1093/petrology/egi023 <https://doi.org/10.1093/petrology/egi023> Earth Sciences Publication - Article PeerReviewed 2005 ftnerc https://doi.org/10.1093/petrology/egi023 2024-05-15T08:42:16Z A suite of dolerite dykes from the Ahlmannryggen region of western Dronning Maud Land (Antarctica) forms part of the much more extensive Karoo igneous province of southern Africa. The dyke compositions include both low- and high-Ti magma types, including picrites and ferropicrites. New 40Ar/39Ar age determinations for the Ahlmannryggen intrusions indicate two ages of emplacement at ~178 and ~190 Ma. Four geochemical groups of dykes have been identified in the Ahlmannryggen region based on analyses of ~60 dykes. The groups are defined on the basis of whole-rock TiO2 and Zr contents, and reinforced by rare earth element (REE), 87Sr/86Sr and 143Nd/144Nd isotope data. Group 1 were intruded at ~190 Ma and have low TiO2 and Zr contents and a significant Archaean crustal component, but also evidence of hydrothermal alteration. Group 2 dykes were intruded at ~178 Ma; they have low to moderate TiO2 and Zr contents and are interpreted to be the result of mixing of melts derived from an isotopically depleted source with small melt fractions of an enriched lithospheric mantle source. Group 3 dyke were intruded at ~190 Ma and form the most distinct magma group; these are largely picritic with superficially mid-ocean ridge basalt (MORB)-like chemistry (flat REE patterns, 87Sr/86Sri ~0·7035, {varepsilon}Ndi ~9). However, they have very high TiO2 (~4 wt %) and Zr (~500 ppm) contents, which is not consistent with melting of MORB-source mantle. The Group 3 magmas are inferred to be derived by partial melting of a strongly depleted mantle source in the garnet stability field. This group includes several high Mg–Fe dykes (ferropicrites), which are interpreted as high-temperature melts. Some Group 3 dykes also show evidence of contamination by continental crust. Group 4 dykes are low-K picrites intruded at ~178 Ma; they have very high TiO2–Zr contents and are the most enriched magma group of the Karoo–Antarctic province, with ocean-island basalt (OIB)-like chemistry. Dykes of Group 1 and Group 3 are sub-parallel (ENE–WSW) and both ... Article in Journal/Newspaper Antarc* Antarctic Antarctica Dronning Maud Land Ocean Island Natural Environment Research Council: NERC Open Research Archive Ahlmannryggen ENVELOPE(-2.500,-2.500,-71.833,-71.833) Antarctic Dronning Maud Land Journal of Petrology 46 7 1489 1524 |
institution |
Open Polar |
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Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
unknown |
topic |
Earth Sciences |
spellingShingle |
Earth Sciences Riley, Teal R. Leat, Philip T. Curtis, Michael L. Millar, Ian L. Duncan, Robert A. Fazel, Adela Early–Middle Jurassic dolerite dykes from western Dronning Maud Land (Antarctica): identifying mantle sources in the Karoo Large Igneous Province |
topic_facet |
Earth Sciences |
description |
A suite of dolerite dykes from the Ahlmannryggen region of western Dronning Maud Land (Antarctica) forms part of the much more extensive Karoo igneous province of southern Africa. The dyke compositions include both low- and high-Ti magma types, including picrites and ferropicrites. New 40Ar/39Ar age determinations for the Ahlmannryggen intrusions indicate two ages of emplacement at ~178 and ~190 Ma. Four geochemical groups of dykes have been identified in the Ahlmannryggen region based on analyses of ~60 dykes. The groups are defined on the basis of whole-rock TiO2 and Zr contents, and reinforced by rare earth element (REE), 87Sr/86Sr and 143Nd/144Nd isotope data. Group 1 were intruded at ~190 Ma and have low TiO2 and Zr contents and a significant Archaean crustal component, but also evidence of hydrothermal alteration. Group 2 dykes were intruded at ~178 Ma; they have low to moderate TiO2 and Zr contents and are interpreted to be the result of mixing of melts derived from an isotopically depleted source with small melt fractions of an enriched lithospheric mantle source. Group 3 dyke were intruded at ~190 Ma and form the most distinct magma group; these are largely picritic with superficially mid-ocean ridge basalt (MORB)-like chemistry (flat REE patterns, 87Sr/86Sri ~0·7035, {varepsilon}Ndi ~9). However, they have very high TiO2 (~4 wt %) and Zr (~500 ppm) contents, which is not consistent with melting of MORB-source mantle. The Group 3 magmas are inferred to be derived by partial melting of a strongly depleted mantle source in the garnet stability field. This group includes several high Mg–Fe dykes (ferropicrites), which are interpreted as high-temperature melts. Some Group 3 dykes also show evidence of contamination by continental crust. Group 4 dykes are low-K picrites intruded at ~178 Ma; they have very high TiO2–Zr contents and are the most enriched magma group of the Karoo–Antarctic province, with ocean-island basalt (OIB)-like chemistry. Dykes of Group 1 and Group 3 are sub-parallel (ENE–WSW) and both ... |
format |
Article in Journal/Newspaper |
author |
Riley, Teal R. Leat, Philip T. Curtis, Michael L. Millar, Ian L. Duncan, Robert A. Fazel, Adela |
author_facet |
Riley, Teal R. Leat, Philip T. Curtis, Michael L. Millar, Ian L. Duncan, Robert A. Fazel, Adela |
author_sort |
Riley, Teal R. |
title |
Early–Middle Jurassic dolerite dykes from western Dronning Maud Land (Antarctica): identifying mantle sources in the Karoo Large Igneous Province |
title_short |
Early–Middle Jurassic dolerite dykes from western Dronning Maud Land (Antarctica): identifying mantle sources in the Karoo Large Igneous Province |
title_full |
Early–Middle Jurassic dolerite dykes from western Dronning Maud Land (Antarctica): identifying mantle sources in the Karoo Large Igneous Province |
title_fullStr |
Early–Middle Jurassic dolerite dykes from western Dronning Maud Land (Antarctica): identifying mantle sources in the Karoo Large Igneous Province |
title_full_unstemmed |
Early–Middle Jurassic dolerite dykes from western Dronning Maud Land (Antarctica): identifying mantle sources in the Karoo Large Igneous Province |
title_sort |
early–middle jurassic dolerite dykes from western dronning maud land (antarctica): identifying mantle sources in the karoo large igneous province |
publisher |
Oxford University Press |
publishDate |
2005 |
url |
http://nora.nerc.ac.uk/id/eprint/1943/ http://petrology.oxfordjournals.org/cgi/content/abstract/46/7/1489 https://doi.org/10.1093/petrology/egi023 |
long_lat |
ENVELOPE(-2.500,-2.500,-71.833,-71.833) |
geographic |
Ahlmannryggen Antarctic Dronning Maud Land |
geographic_facet |
Ahlmannryggen Antarctic Dronning Maud Land |
genre |
Antarc* Antarctic Antarctica Dronning Maud Land Ocean Island |
genre_facet |
Antarc* Antarctic Antarctica Dronning Maud Land Ocean Island |
op_relation |
Riley, Teal R. orcid:0000-0002-3333-5021 Leat, Philip T.; Curtis, Michael L.; Millar, Ian L.; Duncan, Robert A.; Fazel, Adela. 2005 Early–Middle Jurassic dolerite dykes from western Dronning Maud Land (Antarctica): identifying mantle sources in the Karoo Large Igneous Province. Journal of Petrology, 46 (7). 1489-1524. https://doi.org/10.1093/petrology/egi023 <https://doi.org/10.1093/petrology/egi023> |
op_doi |
https://doi.org/10.1093/petrology/egi023 |
container_title |
Journal of Petrology |
container_volume |
46 |
container_issue |
7 |
container_start_page |
1489 |
op_container_end_page |
1524 |
_version_ |
1801383628551225344 |