What types of rocks make up an ophiolite?
Ophiolite is a stratified igneous rock complex composed of upper basalt member, middle gabbro member and lower peridotite member (Fig. 1). Some large complexes measure more than 10 km thick, 100 km wide and 500 km long. The term “ophiolite” means “snake stone” in Greek.
What are the main rocks in an ophiolite suite?
A sequence of rocks consisting of deep-sea marine sediments overlying (from top to bottom) pillow basalts, sheeted dikes, gabbro, dunite, and peridotite.
What are the rock type members of an ophiolite sequence?
An ophiolite sequence consists of variably altered oceanic rocks, including marine sediments, ocean crust, and part of the mantle. The name ophiolite means “snakestone” from “ophio” (snake) and “lithos” (stone) in Greek.
What is an ophiolite rock?
Ophiolite is thrust sheets of ancient oceanic crust and upper part of mantle rocks that have been uplifted and exposed above sea level and often emplaced on top of the continental lithosphere.
Is ophiolite a rock?
ultramafic rocks are known as ophiolites. Many geologists believe that ophiolites formed at oceanic ridges were emplaced by tectonic forces at convergent plate boundaries and then became exposed in highly deformed orogenic (mountain) belts.
What are ultramafic rocks made of?
Ultramafic metamorphic rocks result from the metamorphism of mantle rocks and some oceanic crust and contain dominantly magnesium, silicon, and carbon dioxide, with smaller amounts of iron, calcium, and aluminum.
What is Melange in rock structure?
In geology, a mélange is a large-scale breccia, a mappable body of rock characterized by a lack of continuous bedding and the inclusion of fragments of rock of all sizes, contained in a fine-grained deformed matrix.
What rocks are included in an ophiolite sequence list them stratigraphically from bottom to top?
The stratigraphic sequence observed in an ophiolite corresponds to layered oceanic crust: from top to bottom, an upper layer of oceanic sediment (siliceous or carbonate ooze); a layer of pillow basalt; a layer of sheeted near-vertical dykes; layers of gabbro and plagioclase and mafic cumulates; and a basal layer of “ …
Where can ophiolite be found?
Ophiolites have been found in Cyprus, New Guinea, Newfoundland, California, and Oman. The Samail ophiolite in southeastern Oman has probably been studied in the greatest detail. The rocks probably formed in the Cretaceous not far from the what is now the Persian Gulf.
How do Ophiolites form?
formation. … ultramafic rocks are known as ophiolites. Many geologists believe that ophiolites formed at oceanic ridges were emplaced by tectonic forces at convergent plate boundaries and then became exposed in highly deformed orogenic (mountain) belts.
What kind of rock is an ophiolite made of?
Ophiolite. A term originally applied to rocks consisting mainly of serpentine, but later extended to the rock suite of Alpine-type peridotite s, gabbro s, dolerite s, spilite s and keratophyre s. Now used to define the association of basic to ultrabasic rocks thought to represent oceanic crust.
Where are ophiolites located in the oceanic crust?
An ophiolite is a section of the Earth’s oceanic crust and the underlying upper mantle that has been uplifted and exposed above sea level and often emplaced onto continental crustal rocks. Ophis is Greek for “snake”, and lite (from Greek lithos) means “stone”, after the green-color rocks that make up many ophiolites.
How many types of ophiolites are there in the world?
A recent review of ophiolites proposed classifying them into seven different types: Ligurian-type ophiolites formed during the early opening of an ocean basin like today’s Red Sea. Mediterranean-type ophiolites formed during the interaction of two oceanic plates like today’s Izu-Bonin forearc.
Why are ophiolites important to the big cycle?
A hundred and fifty years after Brongniart, the advent of plate tectonics gave ophiolites a place in the big cycle: they appear to be small pieces of oceanic crust that have been attached to the continents.