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  | isbn    = 0-89181-602-X

  | isbn    = 0-89181-602-X

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Depositional environment influences many aspects of sandstone diagenesis. The flow chart in [[:file:predicting-reservoir-system-quality-and-performance_fig9-51.png|Figure 1]] shows the interrelationship of depositional environment with the many factors controlling sandstone diagenesis.

Depositional environment influences many aspects of sandstone [[diagenesis]]. The flow chart in [[:file:predicting-reservoir-system-quality-and-performance_fig9-51.png|Figure 1]] shows the interrelationship of depositional environment with the many factors controlling sandstone diagenesis.

[[file:predicting-reservoir-system-quality-and-performance_fig9-51.png|300px|thumb|{{figure number|1}}Flow chart showing the interrelationship of depositional environment with the many factors controlling sandstone diagenesis. After Stonecipher et al.<ref name=ch09r60>Stonecipher, S. A., Winn, R. D. Jr., Bishop, M. G., 1984, [http://archives.datapages.com/data/specpubs/sandsto2/data/a059/a059/0001/0250/0289.htm Diagenesis of the Frontier Formation, Moxa Arch: a function of sandstone geometry, texture and composition, and fluid flux], in McDonald, D. A., Surdam, R. C., eds., Clastic Diagenesis: AAPG Memoir 37, p. 289–316.</ref>]]

[[file:predicting-reservoir-system-quality-and-performance_fig9-51.png|400px|thumb|{{figure number|1}}Flow chart showing the interrelationship of depositional environment with the many factors controlling sandstone diagenesis. After Stonecipher et al.<ref name=ch09r60>Stonecipher, S. A., R. D. Winn, Jr., and M. G. Bishop, 1984, [http://archives.datapages.com/data/specpubs/sandsto2/data/a059/a059/0001/0250/0289.htm Diagenesis of the Frontier Formation, Moxa Arch: a function of sandstone geometry, texture and composition, and fluid flux], in D. A. McDonald, and R. C. Surdam eds., Clastic Diagenesis: AAPG Memoir 37, p. 289–316.</ref>]]

==Sediment texture and composition==

==Sediment texture and composition==

Depositional environment affects sediment composition by determining the amount of reworking and [[Core_description#Maturity|sorting]] by size or hydraulic equivalence. Sediments that have a higher degree of reworking are more mechanically and chemically stable. The energy level of depositional environments affects sorting by size or hydraulic equivalence and consequently produces different detrital mineral suites.<ref name=Stonecipher&May1990>Stonecipher, S. A., and J. A. May, 1990, [http://archives.datapages.com/data/specpubs/resmi1/data/a065/a065/0001/0000/0025.htm Facies controls on early diagenesis: Wilcox Group, Texas Gulf Coast], in D. Meshri and P.J. Ortoleva, eds., Prediction of Reservoir Quality Through Chemical Modeling, I: AAPG Memoir 49, p. 25–44.</ref>

Depositional environment affects sediment composition by determining the amount of reworking and [[Core_description#Maturity|sorting]] by size or hydraulic equivalence. Sediments that have a higher degree of reworking are more mechanically and chemically stable. The energy level of depositional environments affects sorting by size or hydraulic equivalence and consequently produces different detrital mineral suites.<ref name=Stonecipher&May1990>Stonecipher, S. A., and J. A. May, 1990, [http://archives.datapages.com/data/specpubs/resmi1/data/a065/a065/0001/0000/0025.htm Facies controls on early diagenesis: Wilcox Group, Texas Gulf Coast], in D. Meshri and P. J. Ortoleva, eds., Prediction of Reservoir Quality Through Chemical Modeling, I: AAPG Memoir 49, p. 25–44.</ref>

For example, different facies of the Wilcox Group along the Gulf Coast of Texas have different compositions that are independent of their source area.<ref name=Stonecipher&May1990 /> Wilcox basal fluvial point bar sands are the coarsest and contain the highest proportion of nondisaggregated lithic fragments. Prodelta sands, deposited in a more distal setting, contain fine quartz, micas, and detrital clays that are products of disaggregation. Reworked sands, such as shoreline or tidal sands, are more quartzose.

For example, different facies of the Wilcox Group along the Gulf Coast of Texas have different compositions that are independent of their source area.<ref name=Stonecipher&May1990 /> Wilcox basal fluvial point bar sands are the coarsest and contain the highest proportion of nondisaggregated lithic fragments. Prodelta sands, deposited in a more distal setting, contain fine [[quartz]], micas, and detrital clays that are products of disaggregation. Reworked sands, such as shoreline or tidal sands, are more quartzose.

==Depositional pore-water chemistry==

==Depositional pore-water chemistry==

Depositional pore-water chemistry of a sandstone is a function of depositional environment. Marine sediments typically have alkaline pore water. Nonmarine sediments have pore water with a variety of chemistries. In nonmarine sediments deposited in conditions that were warm and wet, the pore water is initially either acidic or anoxic and has a high concentration of dissolved mineral species.<ref name=ch09r7>Burley, S., D., Kantorowicz, J., D., Waugh, B., 1985, Clastic diagenesis, in Brenchley, P., J., Williams, B., P., J., eds., Sedimentology: Recent Developments and Applied Aspects: London, Blackwell Scientific Publications, p. 189–228.</ref>

Depositional pore-water chemistry of a sandstone is a function of depositional environment. Marine sediments typically have alkaline pore water. Nonmarine sediments have pore water with a variety of chemistries. In nonmarine sediments deposited in conditions that were warm and wet, the pore water is initially either acidic or anoxic and has a high concentration of dissolved mineral species.<ref name=ch09r7>Burley, S. D., J. D. Kantorowicz, and B. Waugh, 1985, Clastic diagenesis, in P. J. Brenchley, and B. P. J. Williams, eds., Sedimentology: Recent Developments and Applied Aspects: London, Blackwell Scientific Publications, p. 189–228.</ref>

==Marine pore-water chemistry==

==Marine pore-water chemistry==

==Marine diagenesis==

==Marine diagenesis==

[[file:predicting-reservoir-system-quality-and-performance_fig9-52.png|300px|thumb|{{figure number|2}} Typical diagenetic pathways for marine sediments. Copyright: Burley et al.;<ref name=Burley1985>Burley, S. D., J. D. Kantorowicz, and B. Waugh, 1985, Clastic diagenesis, in P. J. Brenchley and B. P. J. Williams, eds., Sedimentology: Recent Developments and Applied Aspects: London, Blackwell Scientific Publications, p. 189–228.</ref> courtesy Blackwell Scientific.]]

[[file:predicting-reservoir-system-quality-and-performance_fig9-52.png|300px|thumb|{{figure number|2}} Typical diagenetic pathways for marine sediments. Copyright: Burley et al.;<ref name=ch09r7 /> courtesy Blackwell Scientific.]]

The precipitation of cements in quartzarenites and subarkoses deposited in a marine environment tends to follow a predictable pattern beginning with clay authigenesis associated with quartz and feldspar overgrowths, followed by carbonate precipitation. Clay minerals form first because they precipitate more easily than quartz and feldspar overgrowths, which require more ordered crystal growth. Carbonate cement stops the further diagenesis of aluminosilicate minerals.

The precipitation of cements in quartzarenites and subarkoses deposited in a marine environment tends to follow a predictable pattern beginning with clay authigenesis associated with [[quartz]] and feldspar overgrowths, followed by carbonate precipitation. Clay minerals form first because they precipitate more easily than quartz and feldspar overgrowths, which require more ordered crystal growth. Carbonate cement stops the further diagenesis of aluminosilicate minerals.

The diagram in [[:file:predicting-reservoir-system-quality-and-performance_fig9-52.png|Figure 2]] summarizes typical diagenetic pathways for marine sediments.

The diagram in [[:file:predicting-reservoir-system-quality-and-performance_fig9-52.png|Figure 2]] summarizes typical diagenetic pathways for marine sediments.

==Nonmarine pore-water chemistry and cements==

==Nonmarine pore-water chemistry and cements==

[[file:predicting-reservoir-system-quality-and-performance_fig9-53.png|300px|thumb|{{figure number|3}}Typical diagenetic pathways for warm and wet nonmarine sediments. Copyright: Burley et al.;<ref name=Burley1985 /> courtesy Blackwell Scientific.]]

[[file:predicting-reservoir-system-quality-and-performance_fig9-53.png|300px|thumb|{{figure number|3}}Typical diagenetic pathways for warm and wet nonmarine sediments. Copyright: Burley et al.;<ref name=ch09r7 /> courtesy Blackwell Scientific.]]

Nonmarine pore-water chemistry falls into two climatic categories: (1) warm and wet or (2) hot and dry. The chemistry of pore waters formed in warm and wet conditions is usually acidic or anoxic with large concentrations of dissolved mineral species. The interaction of organic material with pore water is a critical factor with these waters. The depositional pore water of sediments deposited in hot and dry conditions is typically slightly alkaline and dilute.

Nonmarine pore-water chemistry falls into two climatic categories: (1) warm and wet or (2) hot and dry. The chemistry of pore waters formed in warm and wet conditions is usually acidic or anoxic with large concentrations of dissolved mineral species. The interaction of organic material with pore water is a critical factor with these waters. The depositional pore water of sediments deposited in hot and dry conditions is typically slightly alkaline and dilute.

==Cements==

==Cements==

The table below, compiled from data by Thomas (1983),{{citation needed}} shows the cements that generally characterize specific depositional environments.

The table below, compiled from data by Thomas<ref>Thomas, R., 1983, An introduction to the thin section analysis of the diagenetic histories of clastic rocks, in I. Hutcheon, A. Oldershaw, and R. Thomas, eds., Clastic diagenesis: Canadian Society of Petroleum Geologists Short Course, University of Calgary, chapter 3, 56 p.</ref> shows the cements that generally characterize specific depositional environments.

{| class = "wikitable"

{| class = "wikitable"

| rowspan="2" | Eolian

| rowspan="2" | Eolian

| Dune

| Dune

| Quartz overgrowths dominate; also clay coats

| [[Quartz]] overgrowths dominate; also clay coats

|-

|-

| Interdune

| Interdune

| Grain-coating clays; in areas that were alternately moist and dry anhydrite, dolomite, or calcite common

| Grain-coating clays; in areas that were alternately moist and dry [[anhydrite]], [[dolomite]], or calcite common

|-

|-

| rowspan="2" | Fluvial

| rowspan="2" | Fluvial

==Diagenesis and depositional pore waters==

==Diagenesis and depositional pore waters==

In the Wilcox of the Texas Gulf Coast, certain minerals precipitate as a result of the influence of depositional pore-water chemistry:<ref name=ch09r59>Stonecipher, S., A., May, J., A., 1990, [http://archives.datapages.com/data/specpubs/resmi1/data/a065/a065/0001/0000/0025.htm Facies controls on early diagenesis: Wilcox Group, Texas Gulf Coast], in Meshri, D., Ortoleva, P., J., eds., Prediction of Reservoir Quality Through Chemical Modeling: AAPG Memoir 49, p. 25–44.</ref>

In the Wilcox of the Texas Gulf Coast, certain minerals precipitate as a result of the influence of depositional pore-water chemistry:<ref name=ch09r60 />

* Mica-derived kaolinite characterizes fluvial/distributary-channel sands flushed by fresh water

* Mica-derived kaolinite characterizes fluvial/distributary-channel sands flushed by fresh water

[[Category:Predicting the occurrence of oil and gas traps]]  

[[Category:Predicting the occurrence of oil and gas traps]]  

[[Category:Predicting reservoir system quality and performance]]

[[Category:Predicting reservoir system quality and performance]]