Changes

Composition affects sandstone [[diagenesis]] in two ways:

Composition affects sandstone [[diagenesis]] in two ways:

* The higher the quartz content, the greater the mechanical stability (less compaction occurs).

* The higher the [[quartz]] content, the greater the mechanical stability (less compaction occurs).

* The higher the variety of minerals, the lower the chemical stability (more cementation or dissolution occurs).

* The higher the variety of minerals, the lower the chemical stability (more cementation or dissolution occurs).

Sandstones with abundant lithics, feldspars, or [[chert]] have less occlusion of [[porosity]] by quartz overgrowths and more secondary porosity through dissolution of less stable grains. The ratio of quartz to [[Ductility|ductile]] grains is key to compaction porosity loss.

Sandstones with abundant lithics, feldspars, or [[chert]] have less occlusion of [[porosity]] by quartz overgrowths and more secondary porosity through dissolution of less stable grains. The ratio of quartz to [[Ductility|ductile]] grains is key to compaction porosity loss.

==Influence of sorting on porosity==

==Influence of sorting on porosity==

[[Core_description#Maturity|Sorting]] and porosity strongly correlate in unconsolidated sandstones.<ref name=ch09r5 /> The better the sorting, the higher the porosity. The initial porosities of wet, unconsolidated sands show a range of 44–28% porosity for well-sorted vs. poorly sorted grains. Well-sorted sands tend to have a higher percentage of quartz than do poorly sorted sands, and they tend to maintain higher porosities during burial than poorly sorted sands. Poorly sorted sands have more clay matrix and nonquartz grains.

[[Core_description#Maturity|Sorting]] and porosity strongly correlate in unconsolidated sandstones.<ref name=ch09r5 /> The better the sorting, the higher the porosity. The initial porosities of wet, unconsolidated sands show a range of 44–28% porosity for well-sorted vs. poorly sorted grains. Well-sorted sands tend to have a higher percentage of [[quartz]] than do poorly sorted sands, and they tend to maintain higher porosities during burial than poorly sorted sands. Poorly sorted sands have more clay matrix and nonquartz grains.

==See also==

==See also==