Changes

==Biostratigraphic patterns==

==Biostratigraphic patterns==

Using chronostratigraphically significant bioevents as defined by microfossil extinction events and abundance patterns, local cycles of transgression and [[regression]] can be correlated from well to well, providing a high-resolution calibration of depositional cyclicity. Patterns of relative dilution vs. concentration of fossils that correlate over a significant geographic area, such as a large portion of a basin margin, can be interpreted as reflecting cycles of regional transgression and regression rather than local lateral shifting of sediment input points.

Using chronostratigraphically significant bioevents as defined by microfossil extinction events and abundance patterns, local cycles of transgression and [[regression]] can be correlated from well to well, providing a high-resolution calibration of depositional cyclicity. Patterns of relative dilution vs. concentration of fossils that correlate over a significant geographic area, such as a large portion of a basin margin, can be interpreted as reflecting cycles of regional transgression and regression rather than local [[lateral]] shifting of sediment input points.

Stratigraphic intervals rich in calcareous nannoplankton and foraminiferal fossils and having maximum gamma-ray values are interpreted to correlate with condensed depositional intervals deposited during relative sediment starvation related to transgression.<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> Intervals devoid of fossils or having low abundance values, often associated with sandy lithofacies, can be interpreted as deposited during relative high rates of accumulation related to [[Depocenter#Sediment_supply_rate_and_facies_patterns|progradation]] of the sediment supply into the area of the well, marking a phase of regression. Biofacies are interpreted using benthic foraminiferal assemblages indicative of water mass conditions.<ref name=ch04r97>Tipsword, H., L., J., Setzer, F., M., Smith, F., L. Jr., 1966, Interpretation of depositional environment in Gulf Coast exploration from paleoecology and related stratigraphy: Gulf Coast Assoc. of Geological Societies Transactions, vol. 16, p. 119–130.</ref><ref name=ch04r28>Culver, S., J., 1988, New foraminiferal depth zonation of the northwestern Gulf of Mexico: Palaios, vol. 3, p. 69–85., 10., 2307/3514545</ref><ref name=ch04r7>Armentrout, J., M., 1991, Paleontological constraints on depositional [[modeling]]: examples of integration of biostratigraphy and seismic stratigraphy, Pliocene–Pleistocene, Gulf of Mexico, in Weimer, P., Link, M., H., eds., Seismic Facies and Sedimentary Processes of Submarine Fans and Turbidite Systems: New York, Springer-Verlag, p. 137–170.</ref>

Stratigraphic intervals rich in calcareous nannoplankton and foraminiferal fossils and having maximum gamma-ray values are interpreted to correlate with condensed depositional intervals deposited during relative sediment starvation related to transgression.<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> Intervals devoid of fossils or having low abundance values, often associated with sandy lithofacies, can be interpreted as deposited during relative high rates of accumulation related to [[Depocenter#Sediment_supply_rate_and_facies_patterns|progradation]] of the sediment supply into the area of the well, marking a phase of regression. Biofacies are interpreted using benthic foraminiferal assemblages indicative of water mass conditions.<ref name=ch04r97>Tipsword, H., L., J., Setzer, F., M., Smith, F., L. Jr., 1966, Interpretation of depositional environment in Gulf Coast exploration from paleoecology and related stratigraphy: Gulf Coast Assoc. of Geological Societies Transactions, vol. 16, p. 119–130.</ref><ref name=ch04r28>Culver, S., J., 1988, New foraminiferal depth zonation of the northwestern Gulf of Mexico: Palaios, vol. 3, p. 69–85., 10., 2307/3514545</ref><ref name=ch04r7>Armentrout, J., M., 1991, Paleontological constraints on depositional [[modeling]]: examples of integration of biostratigraphy and seismic stratigraphy, Pliocene–Pleistocene, Gulf of Mexico, in Weimer, P., Link, M., H., eds., Seismic Facies and Sedimentary Processes of Submarine Fans and Turbidite Systems: New York, Springer-Verlag, p. 137–170.</ref>