Ophiolite

(redirected from Ophiolites)
Also found in: Dictionary.
Related to Ophiolites: Benioff Zone, Turbidites

ophiolite

[′äf·ē·ə‚līt]
(petrology)
A distinctive assemblage of mafic plus ultramafic rocks, generally considered to be fragments of oceanic lithosphere that have been tectonically emplaced onto continental margins and island arcs.

Ophiolite

 

a group of ultrabasic and basic intrusive (dunites, peridotites, pyroxenites, various gabbros, tonalites), effusive (primarily basalts and their tuffs), and sedimentary (pelagic oceanic deposits) rocks that are found together.

The concept of ophiolite was introduced by the Swiss scientist G. Steinmann in 1905. Ophiolites are usually associated with the manifestation of magmatism in the early stages of the formation of geosynclinal systems.

During the 1960’s and 1970’s, in connection with intensive study of the oceans, the problem of ophiolites attracted a great deal of attention. Scientists began viewing ophiolites in folded regions as relics of oceanic crust tectonically moved to the margins of the continents. Moreover, serpentinized ultrabasites are viewed as part of the mantle; gabbroids, as the “basalt layer”; and the effusive sedimentary series, as an analogue of the “first” and “second” layers of the present-day oceanic crust. A partial disruption of this sequence of rocks results from the tectonic factors that cause the development of a specific geological formation, a serpentinite rock, in which all members of the ophiolite group, as well as other rocks, are chaotically intermixed and “cemented together” by serpentinites.

Ophiolites are a common component of the earth’s linear folded regions. They are widespread in geosynclinal systems, forming within them protrusions (rock masses tectonically intruded in the solid state into the deposits covering them) or nappes thrust over the miogeosynclinal or platform sediments that overlie the continental crust. The study of ophiolites is important in discovering deposits of chromium, nickel, platinum, gold, mercury, and other ores genetically related to ophiolites, and for studying the historical development of the earth’s crust.

REFERENCES

Peive, A. V. “Okeanicheskaia kora geologicheskogo proshlogo.” Geotektonika, 1969, no. 4.
Hess, H. H. “History of Ocean Basins.” In Buddington Volume. New York, 1962.

A. L. KNIPPER

References in periodicals archive ?
This piece of the Hajar Mountain, between Oman and UAE, is the biggest exposed ophiolite complex in the world.
From north to south these are the Kyrenia Terrane, the Circum-Troodos sedimentary succession, the Troodos Ophiolite complex, and the Mamonia Complex in the south-west (Geological Survey Department 1993).
The Noorabad ophiolite is part of the High Zagros situated between the Zagros Folded Belt and SanandajSirjan Zone (Fig.
The facies is mainly made up of sandsized, moderately-sorted mainly angular to subangular consisting of altered serpentine, chert and subordinate quartz with minor components of pebble-sized clasts ophiolites, micro-quartz, polyquartz and micrite limestone.
southward-convex ophiolites, perhaps reflecting rapid episodes of basin opening, and closure, early quaternary volcanism of Afghanistan, and Pleistocene calcalkaline activity in Koh-i-Sultan.
Martin Flower from University of Illinois while giving his presentation on Plate Collision End-games: A Possible Role for Collision-Induced Mantle Extrusion said their current work focuses on ophiolites in the complex NW India-Asia syntaxis where a collage of accreted micro-continents is associated with a complex sequence of neo-Tethyan basin closure, in many cases post-dating those associated with the hard of India.
With contributions from geologists and earth scientists from throughout the United States, the title contains separate sections for papers on the topics of ophiolites, arcs, and batholiths.
The ophiolites mark the opening and destruction of subduction-related basins, and as such contain important information regarding the tectonic development of the orogen.
Some discoveries have been made in formations beneath ophiolites in the Amanus area, on both sides of the Levant Fracture called Kara Su Valley.
The new discoveries verify some lessons geologists have learned by studying ophiolites - slabs of the ocean floor that have been pushed up onto the continents.
In the Northern Areas the ophiolites have been emplaced along the suture zones between Eurasian and Indo-Pakistan continents and long fault slices.
Mineralization in the area occurs as massive sulfides hosted in ophiolites and gold/antimony in quartz stockworks.