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7463623 
Journal Article 
Petrogenetic evolution of ultramafic rocks from Lesvos Island (NE Aegean, Greece) 
Migiros, G; Hatzipanagiotou, K; Gartzos, E; Serelis, K; Tsikouras, B 
2000 
Yes 
Chemie der Erde: Geochemistry
ISSN: 0009-2819
EISSN: 1611-5864 
60 
1 
27-46 
English 
WOS:000087376000002 
The ophiolitic unit in the SE Lesvos constitutes the uppermost tectonic nappe, consisting of ultramafic rocks with minor gabbroic dykes and an amphibolite sole. The most abundant lithologies comprise lherzolite and harzburgite with minor dunite. The harzburgite member and the dunite are intensively serpentinized. The harzburgite has chemical affinity analogous to Alpine peridotites while the lherzolite is more fertile and resembles some abyssal peridotites. Both have undergone partial melting and depletion as indicated by geochemical and mineralogical results. The exsolution of clinopyroxene and spinel from orthopyroxene indicates elemental redistribution in the pyroxenes and hence geothermometric calculations based on pyroxenes cannot give the original temperatures of formation. Therefore, our geothermobarometric calculations indicate a later cooling episode, which occurred after the formation of porphyroclasts in a temperature range of 1100-650°C and at pressures of about 6-7 kbars. Metasomatic phenomena that affected the Lesvos peridotites resulted in low MgO/FeO(t) ratios and enrichment in some incompatible trace elements together with the formation of amphibole. Chemical affinities and mineralogical compositions suggest that the Lesvos peridotites originated in a marginal basin regime. 
ophiolite; petrogenesis; ultramafic rock