Basalts And Granites

If i type granites are descended from basalts then their formation represents net growth of the continents and net removal from the mantle of elements that are highly concentrated in the crust such as the heat producing radioactive isotopes 40 k and 238 u.

Basalts and granites.

If the melt extrudes onto the surface this can lead to extensive basalt flows that form what are called flood basalts where hundreds of square kilometers of basaltic lava can be produced. If instead they form by melting preexisting crustal rocks they represent a. Granite is an intrusive igneous rock with a felsic composition. Basalt is a dark colored fine grained igneous rock composed mainly of plagioclase and pyroxene minerals.

Granite makes up the cores of continents and much of the bulk of major. The key difference between basalt and granite is that basalt is mostly occurring on ocean floors while granite is in the crust of the earth in all continents. Basalts may be broadly classified on a chemical and petrographic basis into two main groups. The saturation surface for zircon in late stage lunar basalts and granites has been determined over the temperature range1400 1070 c.

Intrusive slowly cooled inside the crust. Igneous rocks are formed by the crystallisation of a magma. The tholeiitic and the alkali basalts. Learn more about basalt in this article.

Earth contains three kinds of rocks namely igneous rocks sedimentary rocks and metamorphic rocks basalt and granite are two types of igneous rocks. 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. Since the rate of cooling and solidification of magmas inside the earth. Below 1200 the saturation surface turns down sharply and becomes nearly temperature independent.

Basalt extrusive igneous volcanic rock that is low in silica content dark in color and comparatively rich in iron and magnesium. The saturation surface in the basalt shows a strong temperature dependence from 1400 to 1200 c. All rocks of igneous origin consist of magma or molten earth that finds its way up to. Granites that form the thick framework of the all continental crusts and also of those defined as anomalous oceanic crusts were mainly extracted in the archean from the upper mantle and later reworked metamorphism anatexis in later.

A basalt is about 53 sio2 whereas granite is 73. Granites are the example of the plutonic intrusive igneous rocks which are formed deep within the earth.