Question 74 Igneous rocks are characterized based on two characteristics: C magm

Question

Question 74 Igneous rocks are characterized based on two characteristics: C magma temperature, composition C volcanic, plutonic C texture, composition C mafic, felsic Question 75 Recall that a batholith is a large body of plutonic rock formed by the coalescing of 40 or more magma chambers. This covers an area of C 20 50 C 75 C 100 Question 76 Volcanic rock cools fast and will have some aspect of fine-grained These rocks are said to be . square kilometers or more. texture. C phaneritic, extrusive aphanitic, extrusive C aphanitic, intrusive phaneritic, intrusive

Explanation / Answer

1. volcanic or plutonic ,

if the igneous rock is formed on the surface then it will be termed volcanic (extrusive) and have a fine grained texture due to rapid cooling. whereas if the rock is formed deep beneath then it will be called plutonic (intrusive) having coarse grained texture.

2. 100

batholiths are large intrusive igneous bodies having transgressive relationship with the host rock. Their diameter is usually 100 km or more and their outcrop is roughly circular or oval.

3. aphanitic, extrusive

if magma cools slowly then crystals get time to grow bigger in size but if lava reaches the surface it does not get much time to grow and rapidly crystallises into fine grained or glassy texture known as aphanitic texture.

since it is formed at the surface it is known as extrusive.

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