Mantle-derived dunite and lherzolite nodules from Ubekendt Ejland, west Greenland Tertiary province
ABSTRACT. Scattered unite and iherzolite nodules occur in one of the youngest basanitoid lavas on Ubekendt Ejland. They have protogranular toporphyroclastic tex-tures. The dunites are oamposed of olivine (Fo93.2-91.9b), enstatite (En93.4_92.8) lOW in Al2Oa and CaO, and Cr-spinel (61-13 % Cr20 3 and...
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| Format: | Text |
| Language: | English |
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1982
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.618.9462 http://www.minersoc.org/pages/Archive-MM/Volume_46/46-340-329.pdf |
| Summary: | ABSTRACT. Scattered unite and iherzolite nodules occur in one of the youngest basanitoid lavas on Ubekendt Ejland. They have protogranular toporphyroclastic tex-tures. The dunites are oamposed of olivine (Fo93.2-91.9b), enstatite (En93.4_92.8) lOW in Al2Oa and CaO, and Cr-spinel (61-13 % Cr20 3 and 3-55 % AI203). A solitary lherzolite module has olivine (Fo94.7_94.1), enstatite (En94.7-94.2), Cr-rich spinel, Ti-phlogopite (11 % TiO2), and hyalophane. Petrographic evidence suggests that the two latter minerals have not been introduced by magmatic injection from the host in spite of the refractory nature of the coexisting phases, and metasomatic processes prior to the last deformation are therefore indicated. Partial melting of such mantle material would presumably pro-duce small amounts of alkaline liquids even at very high |
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