Most Of The Sea Floor Worldwide Is Composed Of Basalt

It is composed of several layers not including the overlying sediment.

Most of the sea floor worldwide is composed of basalt. Oceanic crust is about 6 km 4 miles thick. In fact most of the ocean floor is made of basalt. The columbia river basalts erupted 15 to 17 million years ago cover most of southeastern washington and regions of adjacent oregon. The dark plains on the moon known as maria and possibly the volcanoes on mars and venus are made of basalt.

Basalt the once molten rock that makes up most new oceanic crust is a fairly magnetic substance and scientists began using magnetometers to measure the magnetism of the ocean floor in the 1950s what they discovered was that the magnetism of the ocean floor around. It most commonly forms as an extrusive rock such as a lava flow but can also form in small intrusive bodies such as an igneous dike or a thin sill it has a composition similar to gabbro the difference between basalt and gabbro is that basalt is a fine grained rock while. It can form volcanic islands when it is erupted by volcanoes in ocean basins. Basalt is the most common rock type in the earth s crust the outer 10 to 50 km.

Included in this category are most basalts of the ocean floor most large oceanic islands and continental flood basalts such as the columbia river plateau. The topmost layer about 500 metres 1 650 feet thick includes lavas made of basalt that is rock material consisting largely of plagioclase and pyroxene oceanic crust differs from continental crust in several ways. Vesicular and amygdaloidal textures. It is thinner denser younger and of different.

On earth most basalt magmas have formed by decompression melting of the mantle this can occur in a variety of tectonic settings. Tholeiitic basalt is relatively rich in iron and poor in alkali metals and aluminium. Basalt is a dark colored fine grained igneous rock composed mainly of plagioclase and pyroxene minerals. Huge outpourings of lava called flood basalts are found on many continents.