Changes

===Compaction===

===Compaction===

Compaction reduces the porosity and permeability of a rock by causing the following: (1) grain rotation and rearrangement into a tighter packing configuration, (2) plastic [[deformation]] of [[Ductility|ductile]] grains that flow into adjacent pores and pore throats, (3) [[Fracture|fracturing]] and crushing of [[Brittleness|brittle]] grains, and (4) pressure solution in the form of grain suturing and stylolitization.<ref name=pt06r84>McBride, E. F., 1984, [http://archives.datapages.com/data/bulletns/1984-85/data/pg/0068/0004/0500/0505.htm Compaction in sandstones—influence on reservoir quality]: AAPG Bulletin, v. 68, p. 505.</ref> Rocks that contain mechanically labile grains, such as clay clasts, altered rock fragments, or delicate fossils, are likely to experience a reduction in porosity and permeability as the ductile grains plastically flow into adjacent pore spaces. Brittle grains will fracture, shatter, or in the case of some fossils and porous grains, collapse. A rock that consists of a framework of strong minerals, such as quartz, tends to undergo only minor porosity and permeability reduction during compaction due to grain rotation and rearrangement into a tighter packing configuration.

Compaction reduces the porosity and permeability of a rock by causing the following: (1) grain rotation and rearrangement into a tighter packing configuration, (2) plastic [[deformation]] of [[Ductility|ductile]] grains that flow into adjacent pores and pore throats, (3) [[Fracture|fracturing]] and crushing of [[Brittleness|brittle]] grains, and (4) pressure solution in the form of grain suturing and stylolitization.<ref name=pt06r84>McBride, E. F., 1984, [http://archives.datapages.com/data/bulletns/1984-85/data/pg/0068/0004/0500/0505.htm Compaction in sandstones—influence on reservoir quality]: AAPG Bulletin, v. 68, p. 505.</ref> Rocks that contain mechanically labile grains, such as clay clasts, altered rock fragments, or delicate fossils, are likely to experience a reduction in porosity and permeability as the ductile grains plastically flow into adjacent pore spaces. Brittle grains will fracture, shatter, or in the case of some fossils and porous grains, collapse. A rock that consists of a framework of strong minerals, such as [[quartz]], tends to undergo only minor porosity and permeability reduction during compaction due to grain rotation and rearrangement into a tighter packing configuration.

===Cementation===

===Cementation===

! Cement || Common Crystal Form

! Cement || Common Crystal Form

|-

|-

| Quartz || Syntaxial overgrowth, prismatic

| [[Quartz]] || Syntaxial overgrowth, prismatic

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|-

| Calcite || Fibrous, bladed, granular, blocky, poikilotopic, syntaxial rim

| Calcite || Fibrous, bladed, granular, blocky, poikilotopic, syntaxial rim

| [[Dolomite]] || Rhombohedral, blocky, granular

| [[Dolomite]] || Rhombohedral, blocky, granular

|-

|-

| Anhydrite || Blocky, bladed

| [[Anhydrite]] || Blocky, bladed

|-

|-

| [[Gypsum]] || Blocky, bladed, prismatic

| [[Gypsum]] || Blocky, bladed, prismatic

[[Category:Geological methods]]

[[Category:Geological methods]]