Gondwana break-up related magmatism in the Falkland Islands
Jurassic dykes ( c . 182 Ma) are widespread across the Falkland Islands and exhibit considerable geochemical variability. Orthopyroxene-bearing NW–SE-oriented quartz-tholeiite dykes underwent fractional crystallization at >1 GPa, and major element constraints suggest that they were derived by mel...
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ftgeosoclonfig:oai:figshare.com:article/3454094 2023-05-15T13:33:01+02:00 Gondwana break-up related magmatism in the Falkland Islands M. J. Hole R. M. Ellam D. I. M. Macdonald S. P. Kelley 2016-06-21T11:53:49Z https://doi.org/10.6084/m9.figshare.3454094.v1 https://figshare.com/articles/Gondwana_break-up_related_magmatism_in_the_Falkland_Islands/3454094 unknown doi:10.6084/m9.figshare.3454094.v1 https://figshare.com/articles/Gondwana_break-up_related_magmatism_in_the_Falkland_Islands/3454094 CC BY 4.0 CC-BY Geology Falkland Islands olivine equilibration temperatures lithosphere Nd Falkland Islands Jurassic dykes NW Karoo magma types Sr andesites exhibit geochemical compositions intrusion Dataset 2016 ftgeosoclonfig https://doi.org/10.6084/m9.figshare.3454094.v1 2020-02-21T07:23:46Z Jurassic dykes ( c . 182 Ma) are widespread across the Falkland Islands and exhibit considerable geochemical variability. Orthopyroxene-bearing NW–SE-oriented quartz-tholeiite dykes underwent fractional crystallization at >1 GPa, and major element constraints suggest that they were derived by melting of a pyroxenite-rich source. They have εNd 182 in the range −6 to −11 and 87 Sr/ 86 Sr 182 >0.710 and therefore require an old lithospheric component in their source. A suite of basaltic-andesites and andesites exhibit geochemical compositions transitional between Ferrar and Karoo magma types, and are similar to those seen in the KwaZulu-Natal region of southern Africa and the Theron Mountains of Antarctica. Olivine-phyric intrusions equilibrated at <0.5 GPa, and have isotopic compositions (εNd 182 1.6–3.6 and 87 Sr/ 86 Sr 182 0.7036–0.7058) that require limited interaction with old continental lithosphere. A suite of plagioclase-phyric intrusions with 87 Sr/ 86 Sr 182 c . 0.7035 and εNd 182 c . +4, and low Th/Ta and La/Ta ratios ( c . 1 and c . 15, respectively) also largely escaped interaction with the lithosphere. These isotopically depleted intrusions were probably emplaced synchronously with Gondwana fragmentation and the formation of new oceanic lithosphere. Estimates of mantle potential temperature from olivine equilibration temperatures do not provide unequivocal evidence for the presence of a plume thermal anomaly beneath the Falkland Islands at 182 Ma. Dataset Antarc* Antarctica Geological Society of London: Figshare Theron Mountains ENVELOPE(-28.068,-28.068,-79.044,-79.044) |
institution |
Open Polar |
collection |
Geological Society of London: Figshare |
op_collection_id |
ftgeosoclonfig |
language |
unknown |
topic |
Geology Falkland Islands olivine equilibration temperatures lithosphere Nd Falkland Islands Jurassic dykes NW Karoo magma types Sr andesites exhibit geochemical compositions intrusion |
spellingShingle |
Geology Falkland Islands olivine equilibration temperatures lithosphere Nd Falkland Islands Jurassic dykes NW Karoo magma types Sr andesites exhibit geochemical compositions intrusion M. J. Hole R. M. Ellam D. I. M. Macdonald S. P. Kelley Gondwana break-up related magmatism in the Falkland Islands |
topic_facet |
Geology Falkland Islands olivine equilibration temperatures lithosphere Nd Falkland Islands Jurassic dykes NW Karoo magma types Sr andesites exhibit geochemical compositions intrusion |
description |
Jurassic dykes ( c . 182 Ma) are widespread across the Falkland Islands and exhibit considerable geochemical variability. Orthopyroxene-bearing NW–SE-oriented quartz-tholeiite dykes underwent fractional crystallization at >1 GPa, and major element constraints suggest that they were derived by melting of a pyroxenite-rich source. They have εNd 182 in the range −6 to −11 and 87 Sr/ 86 Sr 182 >0.710 and therefore require an old lithospheric component in their source. A suite of basaltic-andesites and andesites exhibit geochemical compositions transitional between Ferrar and Karoo magma types, and are similar to those seen in the KwaZulu-Natal region of southern Africa and the Theron Mountains of Antarctica. Olivine-phyric intrusions equilibrated at <0.5 GPa, and have isotopic compositions (εNd 182 1.6–3.6 and 87 Sr/ 86 Sr 182 0.7036–0.7058) that require limited interaction with old continental lithosphere. A suite of plagioclase-phyric intrusions with 87 Sr/ 86 Sr 182 c . 0.7035 and εNd 182 c . +4, and low Th/Ta and La/Ta ratios ( c . 1 and c . 15, respectively) also largely escaped interaction with the lithosphere. These isotopically depleted intrusions were probably emplaced synchronously with Gondwana fragmentation and the formation of new oceanic lithosphere. Estimates of mantle potential temperature from olivine equilibration temperatures do not provide unequivocal evidence for the presence of a plume thermal anomaly beneath the Falkland Islands at 182 Ma. |
format |
Dataset |
author |
M. J. Hole R. M. Ellam D. I. M. Macdonald S. P. Kelley |
author_facet |
M. J. Hole R. M. Ellam D. I. M. Macdonald S. P. Kelley |
author_sort |
M. J. Hole |
title |
Gondwana break-up related magmatism in the Falkland Islands |
title_short |
Gondwana break-up related magmatism in the Falkland Islands |
title_full |
Gondwana break-up related magmatism in the Falkland Islands |
title_fullStr |
Gondwana break-up related magmatism in the Falkland Islands |
title_full_unstemmed |
Gondwana break-up related magmatism in the Falkland Islands |
title_sort |
gondwana break-up related magmatism in the falkland islands |
publishDate |
2016 |
url |
https://doi.org/10.6084/m9.figshare.3454094.v1 https://figshare.com/articles/Gondwana_break-up_related_magmatism_in_the_Falkland_Islands/3454094 |
long_lat |
ENVELOPE(-28.068,-28.068,-79.044,-79.044) |
geographic |
Theron Mountains |
geographic_facet |
Theron Mountains |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_relation |
doi:10.6084/m9.figshare.3454094.v1 https://figshare.com/articles/Gondwana_break-up_related_magmatism_in_the_Falkland_Islands/3454094 |
op_rights |
CC BY 4.0 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.6084/m9.figshare.3454094.v1 |
_version_ |
1766037736960032768 |