EAE1011 Lecture Notes - Lecture 10: Igneous Rock, Subduction, Feldspar
6 Aug 2018
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Eae1011 lecture 10 - earth, atmosphere and environment. What happens as the magma rises up through the crust: hot liquid magma melts surrounding rocks and they add to magma may change magma composition if surrounding (country) rocks are chemically different to magma. Surrounding rocks are cooler magma freezes (cools/chills) slowly within them to become rock made of minerals = intrusive rock. Some magma makes its way to the surface (cid:374)o(cid:449) (cid:272)alled (cid:862)la(cid:448)a(cid:863) where it freezes rapidly= Cooling rate determines the mineral size and what you call the rock. Long time for minerals to grow = big crystals = phaneritic= coarse grained: cools slowly within crust = intrusive = plutonic, big crystals means rocks has cooled deeply below the surface, cools quickly at surface = extrusive= volcanic. Short time for minerals to grow = small crystals = aphanitic = fine grained. If cools too fast for minerals to grow = glass.
