Changes

Systems tracts are composed of all deposits accumulating during one phase of relative sea level cycle and preserved between specific primary chronostratigraphic surfaces.<ref name=ch04r23>Brown, L., F., Fisher, W., L., 1977, [http://archives.datapages.com/data/specpubs/seismic1/data/a165/a165/0001/0200/0213.htm Seismic-stratigraphic interpretation of depositional systems: examples from Brazilian rift and pull-apart basins], in Payton, C., E., ed., Seismic Stratigraphy—Applications to Hydrocarbon Exploration: [http://store.aapg.org/detail.aspx?id=1157 AAPG Memoir 26], p. 213–248.</ref> Erosion usually dominates the falling phase of a sea level cycle, and the deposited sediments are most often assigned to the lowstand systems tract.

Systems tracts are composed of all deposits accumulating during one phase of relative sea level cycle and preserved between specific primary chronostratigraphic surfaces.<ref name=ch04r23>Brown, L., F., Fisher, W., L., 1977, [http://archives.datapages.com/data/specpubs/seismic1/data/a165/a165/0001/0200/0213.htm Seismic-stratigraphic interpretation of depositional systems: examples from Brazilian rift and pull-apart basins], in Payton, C., E., ed., Seismic Stratigraphy—Applications to Hydrocarbon Exploration: [http://store.aapg.org/detail.aspx?id=1157 AAPG Memoir 26], p. 213–248.</ref> Erosion usually dominates the falling phase of a sea level cycle, and the deposited sediments are most often assigned to the lowstand systems tract.

==Lowstand systems tracts==

===Lowstand systems tracts===

The lowstand systems tract occurs between the basal sequence boundary and the transgressive surface. Lowstand systems are thickest toward basin centers because much of the basin margin is undergoing erosion. Lowstand systems with shelf-to-slope geometries may have basin center [[gravity]]-flow deposits due to sediment bypass of the slope and thick shelf-edge deltaic systems [[Depocenter#Sediment_supply_rate_and_facies_patterns|prograding]] into deep water. Fluvially dominated depositional systems are common.

The lowstand systems tract occurs between the basal sequence boundary and the transgressive surface. Lowstand systems are thickest toward basin centers because much of the basin margin is undergoing erosion. Lowstand systems with shelf-to-slope geometries may have basin center [[gravity]]-flow deposits due to sediment bypass of the slope and thick shelf-edge deltaic systems [[Depocenter#Sediment_supply_rate_and_facies_patterns|prograding]] into deep water. Fluvially dominated depositional systems are common.

==Transgressive systems tracts==

===Transgressive systems tracts===

The transgressive systems tract encompasses those deposits between the transgressive surface and maximum flooding surface. Transgressive systems tracts show landwardstepping depositional patterns and basin margin onlap due to relative rise in sea level, forcing sediment accumulation toward the basin margin. The basin center is likely to become progressively more sediment starved, and coastal depositional systems may show a strong tidal influence.

The transgressive systems tract encompasses those deposits between the transgressive surface and maximum flooding surface. Transgressive systems tracts show landwardstepping depositional patterns and basin margin onlap due to relative rise in sea level, forcing sediment accumulation toward the basin margin. The basin center is likely to become progressively more sediment starved, and coastal depositional systems may show a strong tidal influence.

==Highstand systems tracts==

===Highstand systems tracts===

The highstand systems tract is between the maximum flooding surface and the overlying sequence boundary. Highstand systems tracts show a [[Depocenter#Sediment_supply_rate_and_facies_patterns|progradational]] stacking pattern due to sediment supply exceeding the accommodation space. Progradation results in basinward downlapping onto the maximum flooding surface. Basin centers may still be sediment starved if shelves are broad. Coastal depositional systems tend to be wave to fluvially dominated, thin, and widespread. Definition and further discussion on identifying characteristics of each of the surface types and systems tracts can be found in Posamentier and Vail,<ref name=ch04r79 /> Loutit et al.,<ref name=ch04r59>Loutit, T., S., Hardenbol, J., Vail, P., R., Baum, G., R., 1988, Condensed sections: the key to age determination and correlation of continental margin sequences: SEPM Special Publication 42, p. 183–213.</ref> Van Wagoner et al.,<ref name=ch04r70>Mitchum, R., M., Jr., Van Wagoner, J., C., 1990, High-frequency sequences and eustatic cycles in the Gulf of Mexico basin: Proceedings, Gulf Coast Section SEPM 11th Annual Research conference, p. 257–267.</ref> and Armentrout.<ref name=ch04r7 /> <ref name=ch04r15>Armentrout, J., M., Malacek, S., J., Mathur, V., R., Neuder, G., L., Ragan, G., M., 1996, Intraslope basin reservoirs deposited by gravity-driven processes: South Ship Shoal and Ewing Banks areas, offshore Louisiana, ''in'' Pacht, J., A., Sheriff, R., E., Perkins, B., F., eds., Stratigraphic Analysis: Utilizing Advanced Geophysical, Wireline, and Borehole Technology for Petroleum Exploration and Production: Proceedings, Gulf Coast Section SEPM 17th Annual Research conference, p. 7–18.</ref>

The highstand systems tract is between the maximum flooding surface and the overlying sequence boundary. Highstand systems tracts show a [[Depocenter#Sediment_supply_rate_and_facies_patterns|progradational]] stacking pattern due to sediment supply exceeding the accommodation space. Progradation results in basinward downlapping onto the maximum flooding surface. Basin centers may still be sediment starved if shelves are broad. Coastal depositional systems tend to be wave to fluvially dominated, thin, and widespread. Definition and further discussion on identifying characteristics of each of the surface types and systems tracts can be found in Posamentier and Vail,<ref name=ch04r79 /> Loutit et al.,<ref name=ch04r59>Loutit, T., S., Hardenbol, J., Vail, P., R., Baum, G., R., 1988, Condensed sections: the key to age determination and correlation of continental margin sequences: SEPM Special Publication 42, p. 183–213.</ref> Van Wagoner et al.,<ref name=ch04r70>Mitchum, R., M., Jr., Van Wagoner, J., C., 1990, High-frequency sequences and eustatic cycles in the Gulf of Mexico basin: Proceedings, Gulf Coast Section SEPM 11th Annual Research conference, p. 257–267.</ref> and Armentrout.<ref name=ch04r7 /> <ref name=ch04r15>Armentrout, J., M., Malacek, S., J., Mathur, V., R., Neuder, G., L., Ragan, G., M., 1996, Intraslope basin reservoirs deposited by gravity-driven processes: South Ship Shoal and Ewing Banks areas, offshore Louisiana, ''in'' Pacht, J., A., Sheriff, R., E., Perkins, B., F., eds., Stratigraphic Analysis: Utilizing Advanced Geophysical, Wireline, and Borehole Technology for Petroleum Exploration and Production: Proceedings, Gulf Coast Section SEPM 17th Annual Research conference, p. 7–18.</ref>