What is an ophiolite in geology?

In Precambrian: Ophiolites. Phanerozoic ophiolites are considered to be fragments of ocean floor that have been trapped between island arcs and continental plates that collided or that have been thrust onto the shelf sediments of continental margins. They consist of a downward sequence of oceanic sediments such…

What type of rock is 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 is ophiolite used for?

Ophiolites may be overprinted by greenschist facies metamorphic assemblages and exhumed during collapse of a thrust-thickened orogen. Ophiolites in orogenic (mountain building) belts represent sutures between two continental plates. Their recognition is therefore important in tectonic reconstructions.

What rocks are in the ophiolite sequence?

From base to top the ophiolite is made of: peridotite, layered gabbro, massive gabbro, dikes, and volcanic rocks. At Samail this entire sequence is 15 km thick. The basal peridotite is made of a rock called harzburgite (made mostly of the minerals olivine and enstatite).

How does an ophiolite form at the subduction zone?

lithosphere, which becomes an ophiolite when incorporated into continental margins through a complex process known as ’emplacement’. A fundamental problem of ophiolite emplacement is how dense oceanic crust becomes emplaced over less dense material(s) of continental margins or subduction-accretion systems.

Where is ophiolite located in the Philippines?

Abstract. The Zambales Ophiolite Complex (ZOC) in the western portion of Luzon Island, Philippines represents a typical exposure of an emplaced crust-upper mantle section of an ancient lithosphere.

What does ophiolite look like?

The name ophiolite means “snakestone” from “ophio” (snake) and “lithos” (stone) in Greek. The rock sequence is named for the brilliant green, snake-like serpentine minerals which form in altered ocean crust and mantle. Ophiolites are rare but nonetheless found throughout the world.

Where do the ophiolite suit of rock occur?

An ophiolite is a section of 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.

What do ophiolite sequences indicate?

Ophiolite sequences are indicators of sea-floor spreading where the oceanic crust is thinned by the forces of plate tectonics, and magma rises to the sea’s floor and generates new crust.

What are the main rocks in an ophiolite suite and how are they formed?

An ophiolite is, therefore, a suite of temporally and spatially associated ultramafic, mafic, and felsic rocks that formed as the products of multiple mantle melting events and magmatic differentiation processes in a particular tectonic environment.

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 “ …

What is Zambales ophiolite?

The Zambales Ophiolite Complex (ZOC) on the island of Luzon, Philippines is one of the most well-studied crust-mantle sequences in the region. Several massifs comprise the ZOC, one of which is the Coto Block overlain by clastic sedimentary units previously dated as Eocene.