EARTH121 Chapter 6: Ch 6 Sedimentary Rocks
29 Aug 2016
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Document Summary
As piles of sediment accumulate, the materials near the bottom are compacted. Over long periods, sediment becomes cemented by mineral matter deposited into the space between particles. Only 5% of earth"s outer 16km, but 75% of all rock outcrops are sediments. Rock layers that sediments form reveal past environments that exist ar the surface. Indicate past environments which their particles were deposited and mechanisms involved in their transport. Diagensis all chemical, physical and biological changes which occur after sediments are deposited but before metamorphism. Burial promotes diagenesis: buried, more pressure and temperatures (150-200c) Upper limit of 200c marks limit between diagenesis and metamorphism. Recrystallization development of more stable minerals from less stable ones. Lithification when unconsolidated materials are transformed into solid sedimentary rocks: compaction and cementation reduce pore space, compaction weight of overlaying material compresses, reduces pore space and fluids driven out. Most significant in fine-grained particles: cementation most important process which converts sediments into sedimentary rock.
