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Modelling the composition of melts formed during continental breakup of the Southeast Greenland margin

Modelling the composition of melts formed during continental breakup of the Southeast Greenland margin
Modelling the composition of melts formed during continental breakup of the Southeast Greenland margin
We have developed a generic dynamic model of extension of the lithosphere, which predicts major element composition and volume of melt generated from initial extension to steady state seafloor spreading. Stokes equations for non-Newtonian flow are solved and the mantle melts by decompression. Strengthening of the mantle due to dehydration as melting progresses is included. The composition is then empirically related to depletion. Using a crystallisation algorithm, the predicted primary melt composition was compared with mean North Atlantic mid-ocean ridge basalt (MORB). At steady state, using half spreading rates from 10 to 20 mm yr? 1 and mantle potential temperatures of 1300 to 1325 °C we predict a major element composition that is within the variation in the mean of North Atlantic MORB.

This model is applied to the Southeast Greenland margin, which has extensive coverage of seismic and ODP core data. These data have been interpreted to indicate an initial pulse of magmatism on rifting that rapidly decayed to leave oceanic crustal thickness of 8 to 11 km. This pattern of melt production can be recreated by introducing an initial hot layer of asthenosphere beneath the continental lithosphere and by having a period of fast spreading during early opening. The hot layer was convected through the melt region giving a pulse of high magnesian and low silica melt during the early rifting process. The predicted major element composition of primary melts generated are in close agreement with primary melts from the Southeast Greenland margin. The observed variations in major element composition are reproduced without a mantle source composition anomaly.
southeast greenland margin, major element composition, large igneous province, ridge–hotspot interaction
0012-821X
248-258
Armitage, John J.
e84ac08b-32e9-4550-b85b-779907832ee1
Minshull, Timothy A.
bf413fb5-849e-4389-acd7-0cb0d644e6b8
Henstock, Timothy J.
27c450a4-3e6b-41f8-97f9-4e0e181400bb
Hopper, John R.
df476df1-ddea-448b-bcaf-bf24f60d24ad
Armitage, John J.
e84ac08b-32e9-4550-b85b-779907832ee1
Minshull, Timothy A.
bf413fb5-849e-4389-acd7-0cb0d644e6b8
Henstock, Timothy J.
27c450a4-3e6b-41f8-97f9-4e0e181400bb
Hopper, John R.
df476df1-ddea-448b-bcaf-bf24f60d24ad

Armitage, John J., Minshull, Timothy A., Henstock, Timothy J. and Hopper, John R. (2008) Modelling the composition of melts formed during continental breakup of the Southeast Greenland margin. Earth and Planetary Science Letters, 269 (1-2), 248-258. (doi:10.1016/j.epsl.2008.02.024).

Record type: Article

Abstract

We have developed a generic dynamic model of extension of the lithosphere, which predicts major element composition and volume of melt generated from initial extension to steady state seafloor spreading. Stokes equations for non-Newtonian flow are solved and the mantle melts by decompression. Strengthening of the mantle due to dehydration as melting progresses is included. The composition is then empirically related to depletion. Using a crystallisation algorithm, the predicted primary melt composition was compared with mean North Atlantic mid-ocean ridge basalt (MORB). At steady state, using half spreading rates from 10 to 20 mm yr? 1 and mantle potential temperatures of 1300 to 1325 °C we predict a major element composition that is within the variation in the mean of North Atlantic MORB.

This model is applied to the Southeast Greenland margin, which has extensive coverage of seismic and ODP core data. These data have been interpreted to indicate an initial pulse of magmatism on rifting that rapidly decayed to leave oceanic crustal thickness of 8 to 11 km. This pattern of melt production can be recreated by introducing an initial hot layer of asthenosphere beneath the continental lithosphere and by having a period of fast spreading during early opening. The hot layer was convected through the melt region giving a pulse of high magnesian and low silica melt during the early rifting process. The predicted major element composition of primary melts generated are in close agreement with primary melts from the Southeast Greenland margin. The observed variations in major element composition are reproduced without a mantle source composition anomaly.

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More information

e-pub ahead of print date: 4 March 2008
Published date: 15 May 2008
Keywords: southeast greenland margin, major element composition, large igneous province, ridge–hotspot interaction
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 58916
URI: https://eprints.soton.ac.uk/id/eprint/58916
ISSN: 0012-821X
PURE UUID: 0de36161-04b7-4cf1-880f-d08193c783a3
ORCID for Timothy A. Minshull: ORCID iD orcid.org/0000-0002-8202-1379
ORCID for Timothy J. Henstock: ORCID iD orcid.org/0000-0002-2132-2514

Catalogue record

Date deposited: 19 Aug 2008
Last modified: 17 Sep 2019 01:02

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