Cyclical variation in composition in continental tholeiites of East Greenland
The Prinsen of Wales Bjerge (PWB), part of the Tertiary volcanic province of East Greenland, consists of tholeiitic basalts overlain by alkalic basalts that were erupted 100–150 km west of the original axis of continental rifting and active ocean-floor development during the creation of the North At...
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1989
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crcansciencepubl:10.1139/e89-045 2024-09-15T18:04:17+00:00 Cyclical variation in composition in continental tholeiites of East Greenland Hogg, A. J. Fawcett, J. J. Gittins, J. Gorton, M. P. 1989 http://dx.doi.org/10.1139/e89-045 http://www.nrcresearchpress.com/doi/pdf/10.1139/e89-045 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 26, issue 3, page 534-543 ISSN 0008-4077 1480-3313 journal-article 1989 crcansciencepubl https://doi.org/10.1139/e89-045 2024-07-25T04:10:07Z The Prinsen of Wales Bjerge (PWB), part of the Tertiary volcanic province of East Greenland, consists of tholeiitic basalts overlain by alkalic basalts that were erupted 100–150 km west of the original axis of continental rifting and active ocean-floor development during the creation of the North Atlantic Ocean. They have many features of continental flood basalts but are somewhat enriched in Fe and in Ti relative to Fe and have slightly lower Al 2 O 3 . They have slight enrichments in the light rare-earth elements (La/Yb = 3–4). A nunatak within the PWB displays four cycles of tholeiitic basalt, each about 50 m thick, which are defined by trace-element variations (Ni, Cr, Sr, Zr, and Zr/Y). In three of the four cycles the lowermost flows are the most highly differentiated, and successive flows are increasingly primitive. These changes are thought to be the result of frequent injection of primitive, mantle-derived tholeiitic magma into small crustal magma chambers that contain evolved tholeiitic magma. The resultant mixing and expulsion of hybrid magma produce flows of small volume (0.01–0.03 km 3 ) that display increasingly primitive character upward within each cycle (increasing Mg# and decreasing content of incompatible elements). This process is expected to be more efficient in small reservoirs than in the very large magma chambers that have been invoked by previous exponents of the differentiation–replenishment hypothesis. We suggest that cyclical volcanism in areas well back from the line of active rifting may be more common than is realized and is controlled by the fractionation–magma-replenishment process operating in numerous small reservoirs in an extensively fractured continental crust. Article in Journal/Newspaper East Greenland Greenland North Atlantic Canadian Science Publishing Canadian Journal of Earth Sciences 26 3 534 543 |
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Open Polar |
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Canadian Science Publishing |
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crcansciencepubl |
language |
English |
description |
The Prinsen of Wales Bjerge (PWB), part of the Tertiary volcanic province of East Greenland, consists of tholeiitic basalts overlain by alkalic basalts that were erupted 100–150 km west of the original axis of continental rifting and active ocean-floor development during the creation of the North Atlantic Ocean. They have many features of continental flood basalts but are somewhat enriched in Fe and in Ti relative to Fe and have slightly lower Al 2 O 3 . They have slight enrichments in the light rare-earth elements (La/Yb = 3–4). A nunatak within the PWB displays four cycles of tholeiitic basalt, each about 50 m thick, which are defined by trace-element variations (Ni, Cr, Sr, Zr, and Zr/Y). In three of the four cycles the lowermost flows are the most highly differentiated, and successive flows are increasingly primitive. These changes are thought to be the result of frequent injection of primitive, mantle-derived tholeiitic magma into small crustal magma chambers that contain evolved tholeiitic magma. The resultant mixing and expulsion of hybrid magma produce flows of small volume (0.01–0.03 km 3 ) that display increasingly primitive character upward within each cycle (increasing Mg# and decreasing content of incompatible elements). This process is expected to be more efficient in small reservoirs than in the very large magma chambers that have been invoked by previous exponents of the differentiation–replenishment hypothesis. We suggest that cyclical volcanism in areas well back from the line of active rifting may be more common than is realized and is controlled by the fractionation–magma-replenishment process operating in numerous small reservoirs in an extensively fractured continental crust. |
format |
Article in Journal/Newspaper |
author |
Hogg, A. J. Fawcett, J. J. Gittins, J. Gorton, M. P. |
spellingShingle |
Hogg, A. J. Fawcett, J. J. Gittins, J. Gorton, M. P. Cyclical variation in composition in continental tholeiites of East Greenland |
author_facet |
Hogg, A. J. Fawcett, J. J. Gittins, J. Gorton, M. P. |
author_sort |
Hogg, A. J. |
title |
Cyclical variation in composition in continental tholeiites of East Greenland |
title_short |
Cyclical variation in composition in continental tholeiites of East Greenland |
title_full |
Cyclical variation in composition in continental tholeiites of East Greenland |
title_fullStr |
Cyclical variation in composition in continental tholeiites of East Greenland |
title_full_unstemmed |
Cyclical variation in composition in continental tholeiites of East Greenland |
title_sort |
cyclical variation in composition in continental tholeiites of east greenland |
publisher |
Canadian Science Publishing |
publishDate |
1989 |
url |
http://dx.doi.org/10.1139/e89-045 http://www.nrcresearchpress.com/doi/pdf/10.1139/e89-045 |
genre |
East Greenland Greenland North Atlantic |
genre_facet |
East Greenland Greenland North Atlantic |
op_source |
Canadian Journal of Earth Sciences volume 26, issue 3, page 534-543 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e89-045 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
26 |
container_issue |
3 |
container_start_page |
534 |
op_container_end_page |
543 |
_version_ |
1810441782436036608 |