Enriched component of the proto-Icelandic mantle plume revealed in alkaline Tertiary lavas from East Greenland

Citation
S. Bernstein et al., Enriched component of the proto-Icelandic mantle plume revealed in alkaline Tertiary lavas from East Greenland, GEOLOGY, 29(9), 2001, pp. 859-862
Citations number
38
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Journal title
GEOLOGY
ISSN journal
0091-7613 → ACNP
Volume
29
Issue
9
Year of publication
2001
Pages
859 - 862
Database
ISI
SICI code
0091-7613(200109)29:9<859:ECOTPM>2.0.ZU;2-D
Abstract
Alkaline ultramafic lavas in north East Greenland were contemporaneous with Tertiary tholeiitic flood basalts in East Greenland. The alkaline lavas ar e enriched in light rare earth elements (REEs) and Ti and Nb, but depleted in Rb, Ba, K, Th, and P. The flood basalts have trace element profiles simi lar to those of the alkaline lavas. These features are not caused by fracti onal crystallization or crustal contamination and are thus regarded as inhe rited from the mantle source. The trace element profiles and Sr and Nd isot opic compositions of the flood basalts are shown to be consistent with a si mple model, in which 5%-10% alkaline melt is mixed into normal-mid-ocean ri dge basalt. This alkaline melt has a composition reflecting low-degree melt ing at high pressures of incompatible element-enriched mantle. In areas whe re only deep melting occurred, this enriched melt component reached the sur face in an essentially undiluted form. Elsewhere, under the rift axis, it m ixed with asthenospheric melts, resulting in the typical enriched character istics of East Greenland flood basalts. The presence of pronounced negative P anomalies in modern Iceland lavas suggests this to be a long-term featur e of the Iceland mantle plume.