plate tectonics …of ocean crust, known as ophiolites, are preserved on land. They provide a valuable natural laboratory for studying the composition and character of the oceanic crust and the mechanisms of their emplacement and preservation on land.

Where are ophiolites 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.

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 an igneous?

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 does an ophiolite represent?

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. The suffix lite from the Greek lithos means “stone”.

What is the significance of ophiolites?

Thus, ophiolites in the geologic record provide evidence primarily of subduction zone tectonics, not mid-ocean ridge spreading. Although they typically lie between continental blocks, their emplacement may predate final closure of the ocean basin in which they formed by many millions of years.

What is the meaning of accretionary wedge?

Sediments, the top layer of material on a tectonic plate, that accumulate and deform where oceanic and continental plates collide. These sediments are scraped off the top of the downgoing oceanic crustal plate and are appended to the edge of the continental plate.

What causes a subduction zone?

Oceanic crust is denser than continental crust. At a subduction zone, the oceanic crust usually sinks into the mantle beneath lighter continental crust. (Sometimes, oceanic crust may grow so old and that dense that it collapses and spontaneously forms a subduction zone, scientists think.)

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 rocks are included in 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.

Where does the name ophiolite come from in geology?

Why are peridotite nodules important to paleogeologists?

Some of the nodules preserve isotope ratios of osmium and other elements that record processes that occurred when Earth was formed, and so they are of special interest to paleogeologists because they provide clues to the early composition of Earth’s mantle and the complexities of the processes that occurred.

How are geologists used in the real world?

If geologists can prepare maps of areas that have flooded in the past, they can prepare maps of areas that might be flooded in the future. These maps can be used to guide the development of communities and determine where flood protection or flood insurance is needed. Geologists study Earth materials: People use Earth materials every day.

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