NJG80-2-03
2000
Geochemistry and petrogenesis of extrusive rocks,dykes and high-level plutonic rocks on the island of Oldra, Solund-Stavfjord Ophiolite Complex, western Norway
80
2
pp. 97-110

The island of Oldra, part of the Late Ordovician Solund-Stavfjord Ophiolite Complex of the western Norwegian Caledonides, comprises extrusive rocks, a sheeted dyke complex and high-level gabbros. The metabasalts are of N-MORB affinity, and their Nd isotopic composition (?Nd=+ 7.8 to +8.4) indicates generation from a relatively homogeneous, bul strongly depleted mantle. Eighty percent of the metabasalts classify as FeTi-basalts (FeOt/MgO >1. 75, TiO2 > 2 wt% ), but pseudostratigraphically their distribution varies significantly (51% of the extrusive rocks and 92% of the sheeted dykes). The contents of FeOt, MgO, Al2O3, Cr, Ni and Zr indicate that differences in depth of melting (30 to 12 kbar), crystal fractionation of olivine, plagioclase and clinopyroxene at different levels in the mantle and crust (

Hanne Lone Ryttvad, Norsk Hydro ASA, Sandslivn. 90, N0-5049 Bergen, Norway;
Harald Furnes, Geologisk Institutt, Allégt. 41, NO-5007 Bergen, Norway (e-mail. This email address is being protected from spambots. You need JavaScript enabled to view it.);
Kjell Petter Skjerlie, Institutt for Geologi, N0-9037 Tromsø, Norway;
Rinn Rolfsen, Esso Norge AS, Grensevn. 6, N0-4313 Sandnes, Norway

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0029-196X