Explain why the Composition of the Plagioclase Feldspar may vary within an Intrusion.

Ca plagioclase forms early meaning that it settles down through the magma body and forms in the lower part of the intrusion and solidifies. Na rich plagioclase forms later so is only present in the middle and upper parts of the intrusion – the part of the intrusion which solidifies last. 

AG
Answered by Arthur G. Geology tutor

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