Abstract
The mineralogical and geochemical features of the lower Ordovician Betts Cove ophiolite of northeastern Newfoundland indicate that hydrothermal circulation of seawater near a mid-ocean ridge has been involved in the metamorphism of the complex. The degree of greenschist facies metamorphism increases with stratigraphie depth in the ophioli te. Calcite, hematite and epidote distributions show that the metamorphosing fluid penetrated downward and was reduced with depth. The mobilities of major and trace elements support the hypothesis of the interaction of seawater and basalt: Fe2O3, MgO, Na2O and H2O increase whereas CaO and Cu decrease in the rock after alteration; SiO2, total iron, K2O, Ba and Rb can either be depleted or enhanced in the altered material; TiO2, P2O5, Zr, Y, Cr and Ni remain stable during the metamorphic episode. Finally, the occurrence of massive sulphides and incipient rodingitic gabbro is explicable in a circulatory seawater system.
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Coish, R.A. Ocean floor metamorphism in the Betts Cove ophiolite, Newfoundland. Contr. Mineral. and Petrol. 60, 255–270 (1977). https://doi.org/10.1007/BF01166800
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DOI: https://doi.org/10.1007/BF01166800