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Seismic sounding of mid-ocean ridges has revealed only a few magma chambers beneath ridges, and these are quite thin.
A few deep drill holes into oceanic crust have intercepted gabbro, but it is not layered like ophiolite gabbro.
The term ophiolite was originally used by Alexandre Brongniart later modified its use to include serpentine, pillow lava, and chert ("Steinmann's trinity"), again based on occurrences in the Alps.
The term was little-used in other areas until the late 1950s to early 1960s, with the recognition that this assemblage provided another term for oceanic crust and the process of seafloor spreading.
Ophio is Greek for snake, and lite means stone from the Greek lithos, after the often-green-color rocks that make up many ophiolites.This insight was one of the founding pillars of plate tectonics, and ophiolites have always played a central role in plate tectonic theory and the interpretation of ancient mountain belts.This definition has been challenged recently because new studies of oceanic crust by the Integrated Ocean Drilling Program and other research cruises have shown that in situ ocean crust can be quite variable, and that in places volcanic rocks sit directly on peridotite tectonite, with no intervening gabbros.This recognition was tied to two events: (1) the observation of magnetic anomaly stripes on the seafloor, parallel to oceanic ridge systems, interpreted by Frederick Vine and Drummond Matthews to represent the formation of new crust at the oceanic ridge and its subsequent symmetric spreading away from that ridge, and (2) the observation of a sheeted dyke complex within the Troodos Ophiolite (Cyprus) by Ian Graham Gass and co-workers, which must have formed by repetitive extension of crust and intrusion of magma, resulting in a formation consisting of 100% dikes with no older wall rocks preserved within the complex.Moores and Vine Their great significance relates to their occurrence within mountain belts such as the Alps or the Himalayas, where they document the existence of former ocean basins that have now been consumed by subduction.