GLG 301 Lecture Notes - Lecture 3: Oceanic Crust, Subduction, Igneous Differentiation
Document Summary
History from the rocks: classification of rocks and the rock cycle. Naturally occurring aggregates of minerals (and by definition glass* and coal**) Texture (grain/crystal size) texture/composition can tell us a lot about the history of the rock. A glass is a solid with no coherent (crystalline) structure - in geology usually formed when something is cooled very rapidly; **organic sedimentary rock. Formed from the cooling of molten rock (magma) either on or below the surface of the earth. Rock melt if one/more of the following occurs: Increase temperatures past melting point (solidus*) of specific minerals. Usually by bringing hot material (or magma) up into cooler areas. Melting of only some minerals/some fraction of a specific mineral is called partial melting. Decompression by rising hot mantle rock (plumes) In particular, water is brought to depth by the process of subduction. Magma forms at relatively shallow depths (<100 km or so) Temperature below which minerals are completely solid.
