Deep mantle plume osmium isotope signature from West Greenland Tertiary picrites
Picrites from Nuussuaq Peninsula and Qeqertarssuaq (Disko) Island, West Greenland, preserve trace element and isotopic signatures reflecting the composition of the Icelandic plume head. Os isotope ratios are low ( 187 Os/ 188 Os (i) =0.1272–0.1371) in terms of global plume related magmatism, and thi...
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ftopenunivgb:oai:oro.open.ac.uk:29113 2023-06-11T04:12:07+02:00 Deep mantle plume osmium isotope signature from West Greenland Tertiary picrites Schaefer, Bruce F. Parkinson, Ian Hawkesworth, Chris J. 2000 https://oro.open.ac.uk/29113/ https://doi.org/10.1016/S0012-821X(99)00290-3 unknown Schaefer, Bruce F.; Parkinson, Ian <http://oro.open.ac.uk/view/person/ijp5.html> and Hawkesworth, Chris J. (2000). Deep mantle plume osmium isotope signature from West Greenland Tertiary picrites. Earth and Planetary Science Letters, 175(1-2) pp. 105–118. Journal Item None PeerReviewed 2000 ftopenunivgb https://doi.org/10.1016/S0012-821X(99)00290-3 2023-05-28T05:46:44Z Picrites from Nuussuaq Peninsula and Qeqertarssuaq (Disko) Island, West Greenland, preserve trace element and isotopic signatures reflecting the composition of the Icelandic plume head. Os isotope ratios are low ( 187 Os/ 188 Os (i) =0.1272–0.1371) in terms of global plume related magmatism, and this is coupled with anomalously high Os abundances and radiogenic 143 Nd/ 144 Nd (i) isotopes. Crustally contaminated basalts within the West Greenland sequences possess Os and Nd isotopic signatures consistent with mixing between initial plume head compositions and two discrete types of West Greenland continental crust. One crustal component is of a local sedimentary origin, and the other is typical of ancient felsic crust. The low Os isotopic signatures of the picritic units are considered to be those of the initial mantle plume. The fact that such low Os isotope ratios occur in sequences with high 3 He/ 4 He, and the non-systematic variation in Os isotopes with indices of fractionation/accumulation and Pb isotopes, argue against mixing with depleted MORB mantle or ancient subcontinental lithospheric mantle. The high Os concentrations in the picrites are attributed to high degrees of partial melting (>25%) of mantle containing no residual sulphide. This is consistent with models for plume heads in which anomalous mantle temperatures initiate melting at high pressures generating large degrees of partial melting. Unradiogenic Os and radiogenic Nd components in plume-related CFB magmatism may preserve contributions from a reservoir which is sampled only occasionally in young oceanic basalts. Such a reservoir shares Os isotopic features with the primitive upper mantle (PUM), which may also be manifest in the ‘Kea’ component of Hawaiian magmatism. Therefore, portions of the West Greenland continental flood basalt province arguably represent the first direct sampling of unmodified plume head material derived from the lower mantle or lower portions of the upper mantle. Article in Journal/Newspaper Greenland Nuussuaq The Open University: Open Research Online (ORO) Greenland Nuussuaq ENVELOPE(-51.918,-51.918,66.626,66.626) Earth and Planetary Science Letters 175 1-2 105 118 |
institution |
Open Polar |
collection |
The Open University: Open Research Online (ORO) |
op_collection_id |
ftopenunivgb |
language |
unknown |
description |
Picrites from Nuussuaq Peninsula and Qeqertarssuaq (Disko) Island, West Greenland, preserve trace element and isotopic signatures reflecting the composition of the Icelandic plume head. Os isotope ratios are low ( 187 Os/ 188 Os (i) =0.1272–0.1371) in terms of global plume related magmatism, and this is coupled with anomalously high Os abundances and radiogenic 143 Nd/ 144 Nd (i) isotopes. Crustally contaminated basalts within the West Greenland sequences possess Os and Nd isotopic signatures consistent with mixing between initial plume head compositions and two discrete types of West Greenland continental crust. One crustal component is of a local sedimentary origin, and the other is typical of ancient felsic crust. The low Os isotopic signatures of the picritic units are considered to be those of the initial mantle plume. The fact that such low Os isotope ratios occur in sequences with high 3 He/ 4 He, and the non-systematic variation in Os isotopes with indices of fractionation/accumulation and Pb isotopes, argue against mixing with depleted MORB mantle or ancient subcontinental lithospheric mantle. The high Os concentrations in the picrites are attributed to high degrees of partial melting (>25%) of mantle containing no residual sulphide. This is consistent with models for plume heads in which anomalous mantle temperatures initiate melting at high pressures generating large degrees of partial melting. Unradiogenic Os and radiogenic Nd components in plume-related CFB magmatism may preserve contributions from a reservoir which is sampled only occasionally in young oceanic basalts. Such a reservoir shares Os isotopic features with the primitive upper mantle (PUM), which may also be manifest in the ‘Kea’ component of Hawaiian magmatism. Therefore, portions of the West Greenland continental flood basalt province arguably represent the first direct sampling of unmodified plume head material derived from the lower mantle or lower portions of the upper mantle. |
format |
Article in Journal/Newspaper |
author |
Schaefer, Bruce F. Parkinson, Ian Hawkesworth, Chris J. |
spellingShingle |
Schaefer, Bruce F. Parkinson, Ian Hawkesworth, Chris J. Deep mantle plume osmium isotope signature from West Greenland Tertiary picrites |
author_facet |
Schaefer, Bruce F. Parkinson, Ian Hawkesworth, Chris J. |
author_sort |
Schaefer, Bruce F. |
title |
Deep mantle plume osmium isotope signature from West Greenland Tertiary picrites |
title_short |
Deep mantle plume osmium isotope signature from West Greenland Tertiary picrites |
title_full |
Deep mantle plume osmium isotope signature from West Greenland Tertiary picrites |
title_fullStr |
Deep mantle plume osmium isotope signature from West Greenland Tertiary picrites |
title_full_unstemmed |
Deep mantle plume osmium isotope signature from West Greenland Tertiary picrites |
title_sort |
deep mantle plume osmium isotope signature from west greenland tertiary picrites |
publishDate |
2000 |
url |
https://oro.open.ac.uk/29113/ https://doi.org/10.1016/S0012-821X(99)00290-3 |
long_lat |
ENVELOPE(-51.918,-51.918,66.626,66.626) |
geographic |
Greenland Nuussuaq |
geographic_facet |
Greenland Nuussuaq |
genre |
Greenland Nuussuaq |
genre_facet |
Greenland Nuussuaq |
op_relation |
Schaefer, Bruce F.; Parkinson, Ian <http://oro.open.ac.uk/view/person/ijp5.html> and Hawkesworth, Chris J. (2000). Deep mantle plume osmium isotope signature from West Greenland Tertiary picrites. Earth and Planetary Science Letters, 175(1-2) pp. 105–118. |
op_doi |
https://doi.org/10.1016/S0012-821X(99)00290-3 |
container_title |
Earth and Planetary Science Letters |
container_volume |
175 |
container_issue |
1-2 |
container_start_page |
105 |
op_container_end_page |
118 |
_version_ |
1768387763170705408 |