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Origin of the Igneous Rocks

We can find the mineral composition of igneous rocks by means of studying the chemical composition of the magma from which the rock has been crystallized. Because there is a large variety of igneous rocks, thus it was originally thought an equally large variety of magma also existed. But the later research found out that there are only two types of magma existed and all types of igneous rocks were derived from them.

Differentiation of Magma while cooling and solidification

Magmatic Differentiation: Magmatic differentiation means the split of magma into various parts due to the presence of different types of chemicals in it. These parts of magma on cooling and solidification produce rocks of different types. As the chemical composition of magma differs in its different parts and layers, the newly born rocks also differ …

Formation of Igneous Rocks

The igneous rocks are formed from the cooling and solidification of the Magma/Lava. The minerals and the chemical makeup of igneous rocks are important in order to understand their formation. Experimental studies of the crystallization sequence of minerals from a melt have helped greatly in understanding the origin of igneous rocks. The temperature-composition diagrams involving …

Mechanics of Intrusion

Source of Magma:  Magma is originated from the upper mantle, which lies just under the crust, and is nearly molten. A slight drop in pressure caused by dee faulting etc, completes the melting process. The basaltic magma originates in this manner, while the “granitic magma” can be produced in two ways: (a) from melting of …

Forms of Igneous Bodies

The igneous material is of two types; one is extrusive, and the other is intrusive. The extrusive igneous bodies are formed from the magma poured out at the surface of the earth. The lava flows are examples of extrusive igneous material. While the igneous bodies are formed by the consolidation of magma at some depth …

Structures of Igneous Rocks

Once the molten magma extrudes out, it is affected by several factors. These factors provide varied structures to the rocks on cooling. Some important factors are as under; (1). Flow Structures: Sometimes an igneous rock shows parallel or subparallel bands or streaks which are caused by the flow of magma or lava during cooling and …

Texture of the igneous rocks

The texture of the igneous rocks: The size, shape, and arrangement of mineral grains in a rock are known as their texture. The grain size of the igneous rocks depends on the rate of cooling of magma. In general, slower is the rate of cooling, the coarser is the grain of rock. In the study …

Occurrence of Igneous Rocks

The interior of the earth is very hot. Due to this intense heat, the internal matter of the earth is molten. The molten material of the earth is known as Magma. Magma is produced deep in the earth’s crust where temperatures are very high ranging from 900 degrees Celsius to 1600 degrees celsius. Magma being …

Chemical Composition of Igneous Rocks

Igneous rocks make approximately 90% of the earth’s crust by volume. But their great abundance is hidden on the earth’s surface by a relatively thin layer of sedimentary and metamorphic rocks. Igneous rocks are formed by the cooling and solidification of magma. Magma is a hot viscous, siliceous melt containing water vapour and gases. It …