Chapter 7 Notes - sedimentary rocks a) Compaction: most...

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Chapter 7: Sedimentary Rocks I) Sedimentary rocks: made of sediments that are from weathering A) Constituent 5% by volume of earth’s outer 16km B) At the surface about 75% is sedimentary rocks C) Comprises a relatively thin and discontinuous layer in uppermost portion of crust D) Contains fossils and is important economically II) Diagenesis: all of the chemical, physical, and biological changes that take place after sediments are  deposition and during and after lithification A) Promoted by burial B) Subjected to increasingly higher temp. and pressure C) Occurs within upper few km. of earth’s crust at temp. less than 150 o  to 200 oc D) Includes: 1) Recrystallization: development of more stable minerals from less stable ones 2) Lithification: processes by which unconsolidated sediments are transformed into solid 
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Unformatted text preview: sedimentary rocks a) Compaction: most common physical change i) Weight of overlying material compresses the deeper sediments ii) Reduction in pore spacewater is driven out iii) Most significant process in fine-grained sedimentary rocks b) Cementation: most important process by which sediments are converted to sedimentary rock i) Chemical diagenetic change Involves precipitation of minerals among individual sediment grains Cementing materials are carried in solution by water percolating through open spaces b/t particles Cement precipitates onto sediment grains, fills open spaces, and joins particles ii) Addition of cement reduces its porosity iii)...
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