| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Journal of Petrology | Volume 44 | Number 11 | Pages 2081-2112 | 2003
© Oxford University Press 2003; all rights reserved
An Isotope and Trace Element Study of the East Greenland Tertiary Dyke Swarm: Constraints on Temporal and Spatial Evolution during Continental Rifting
DANISH LITHOSPHERE CENTRE, ØSTER VOLDGADE 10, 1350 COPENHAGEN K, DENMARK
* Corresponding author. Present address: Woods Hole Oceanographic Institution, G&G, MS# 8, Woods Hole, MA 02543, USA. Telephone: +1 (508) 289 2946. Fax +1 (508) 457 2183. E-mail: khanghoj{at}whoi.edu
Dykes of the East Greenland Tertiary dyke swarm can be divided into pre- and syn-break-up tholeiitic dykes, and post-break-up transitional dykes. Of the pre- and syn-break-up dykes, the most abundant group (Tholeiitic Series; TS) has major element compositions similar to the main part of the East Greenland flood basalts. A group of high-MgO tholeiitic dykes (Picrite–Ankaramite Series; PAS) are much less common, and are equivalent to some of the oldest lavas of the East Greenland flood basalts. Isotopic compositions of the TS and PAS dykes partly overlap with those for Iceland, but Pb isotopic compositions extend to less radiogenic values than those seen in either Iceland or North Atlantic mid-ocean ridge basalt (MORB). The isotopically depleted source required to account for this isotopic variation is interpreted as subcontinental lithospheric mantle with low 87Sr/86Sr and 206Pb/204Pb and high 
Nd. The post-break-up Transitional Series (TRANS) dykes are isotopically distinct from Iceland and MORB, and are interpreted as the products of contamination of Iceland plume melts with continental crust. Comparison of the Nd–Sr–Pb isotopic and trace element compositions of dykes from different segments of the East Greenland margin indicates that there is no systematic compositional change with distance from the presumed proto-Icelandic plume centre. This suggests that a northward-increasing crustal thickness observed offshore may be attributed to active upwelling rather than a systematic rise in temperature towards the plume centre.
KEY WORDS: isotopes; trace elements; mantle sources; mantle melting
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  J. HANSEN, D. A. JERRAM, K. McCAFFREY, and S. R. PASSEY The onset of the North Atlantic Igneous Province in a rifting perspective Geological Magazine, May 1, 2009; 146(3): 309 - 325. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Storey, A.K. Pedersen, O. Stecher, S. Bernstein, H.C. Larsen, L.M. Larsen, J.A. Baker, and R.A. Duncan Long-lived postbreakup magmatism along the East Greenland margin: Evidence for shallow-mantle metasomatism by the Iceland plume Geology, February 1, 2004; 32(2): 173 - 176. [Abstract] [Full Text] [PDF]
|
|