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Hydrous partial melting within the lower oceanic crust
journal contributionposted on 2023-05-17, 10:58 authored by Koepke, J, Sandrin FeigSandrin Feig, Snow, J
We studied more than 60 oceanic gabbros from the recent oceanic crust and from ophiolites (East Pacific Rise, Mid-Atlantic Ridge, Southwest Indian Ridge, Oman ophiolite) by scanning electron microscopy and found in nearly all samples microstructures suggesting that hydrous partial melting reactions proceeded. The characteristic paragenesis consists of orthopyroxene and pargasite rimming olivine and clinopyroxene primocrysts in intimate contact with neoblastic plagioclase strongly enriched in anorthite. This is in agreement with recent water-saturated melting experiments on a variety of natural gabbros between 900 and 1000 Â°C. The observed microtextures in the natural gabbros imply the propagation of water-rich fluids on grain boundaries in a ductile regime causing hydrous partial melting. Thus, this type of hydrothermal activity proceeds within the deep oceanic crust at very high temperatures (900-1000 Â°C) without a crack system, a prerequisite in current models for enabling hydrothermal circulation. Â© 2005 Blackwell Publishing Ltd.
Publication titleTerra Nova: The European Journal of Geosciences
PublisherBlackwell Publishing Ltd
Place of publication9600 Garsington Rd, Oxford, England, Oxon, Ox4 2Dg
Rights statementThe definitive published version is available online at: http://www3.interscience.wiley.com/