Lithospheric mantle evolution during continental break-up: the West Iberia non-volcanic passive margin

• Main Authors: Gilles Chazot, Sophie Charpentier, Riccardo Vannucci, Béatrice Luais
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2005
• Subjects: North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.565.3505; http://petrology.oxfordjournals.org/content/early/2005/07/25/petrology.egi064.full.pdf

Ultramafic (lherzolites, metasomatized peridotites, harzburgites, websterites and clinopyroxenites) and mafic igneous (basalts, dolerites, diorites and gabbros) rocks exposed at the sea-floor along the West Iberia continental margin represent a rare oppor-tunity to study the transition zone between continental and oceanic lithosphere. The igneous rocks are enriched in LREE, unlike North Atlantic MORB. A correlation between their 143Nd/144Nd iso-topic composition and Ce/Yb ratio suggests that they originate from mixing between partial melts of a depleted mantle source similar to DMM and of an enriched mantle source which may reside within the continental lithosphere. Clinopyroxenes and amphiboles in the ultramafic rocks are LREE depleted and have flat HREE patterns with concentrations higher than those of abyssal peridotites. Clino-pyroxenes in the harzburgites are less LREE depleted but have lower HREE concentrations. The clinopyroxenes in the Galicia