TY - JOUR

T1 - Modelling the composition of melts formed during continental breakup of the Southeast Greenland margin

AU - Armitage, John J.

AU - Henstock, Timothy J.

AU - Minshull, Timothy A.

AU - Hopper, John R.

N1 - Funding Information: We are grateful to Simon Dean for the use of his melt parameterisation code. We would also like to thank David Sparks, Charles Lesher and Bramley Murton for constructive and enjoyable discussions regarding various aspects of this paper. This project was supported by the NERC Oceans Margins LINK thematic program through a studentship for John Armitage. We would also like to thank Claude Jaupart and an anonymous reviewer for their constructive comments.

PY - 2008/5/15

Y1 - 2008/5/15

N2 - 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.

AB - 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.

KW - large igneous province

KW - major element composition

KW - ridge-hotspot interaction

KW - Southeast Greenland margin

UR - http://www.scopus.com/inward/record.url?scp=42649126343&partnerID=8YFLogxK

U2 - 10.1016/j.epsl.2008.02.024

DO - 10.1016/j.epsl.2008.02.024

M3 - Journal article

AN - SCOPUS:42649126343

VL - 269

SP - 248

EP - 258

JO - Earth and Planetary Science Letters

JF - Earth and Planetary Science Letters

SN - 0012-821X

IS - 1-2

ER -