Changes

==Interpretation of stratal patterns example==

==Interpretation of stratal patterns example==

Relative changes in sea level can also be inferred from detailed analysis of local depositional geometries on [[Seismic data|seismic reflection profiles]]. On the seismic reflection profile schematic in [[:file:sedimentary-basin-analysis_fig4-27.png|Figure 8]]<ref name=ch04r6>Armentrout, J. M., 1987, Integration of biostratigraphy and seismic stratigraphy: Pliocene–Pleistocene, Gulf of Mexico: Proceedings, Gulf Coast Section SEPM 8th Annual Research Conference, p. 6–14.</ref> clinoforms 1-5 [[pinch out]] with [http://homepage.ufp.pt/biblioteca/Seismic/Pages/Page22.htm toplap] against a common horizon, suggesting oblique clinoforms.<ref name=ch04r68>Mitchum, R., M., Jr., 1977, [http://archives.datapages.com/data/specpubs/seismic1/data/a165/a165/0001/0200/0205.htm Seismic stratigraphy and global changes in sea level, 11: Glossary of terms used in seismic stratigraphy], in Seismic Stratigraphy—Applications in Hydrocarbon Exploration: [http://store.aapg.org/detail.aspx?id=1157 AAPG Memoir 26], p. 205–212.</ref> These oblique [http://unterm.un.org/DGAACS/unterm.nsf/8fa942046ff7601c85256983007ca4d8/6d701a3f58b3c00d852570d70052c711?OpenDocument clinoforms] can be interpreted as forming when sediment supply exceeds the accommodation space and causes shelf-margin [[Depocenter#Sediment_supply_rate_and_facies_patterns|progradation]]; sea level falls at the same rate as subsidence, completely bypassing the shelf with no accumulation of seismic-scale [http://www.merriam-webster.com/dictionary/topset%20beds topset] beds. Clinoforms 6 and 7 are sigmoidal<ref name=ch04r68 /> These can be interpreted as sediment supply exceeding accommodation space, forcing progradation but with subsidence exceeding the relative change in sea level and consequent accumulation of topset beds. The change from no topset beds to [[Depocenter#Sediment_supply_rate_and_facies_patterns|aggradational]] topset beds indicates a turnaround from apparent still-stand to apparent rise in sea level at the site of deposition.

Relative changes in sea level can also be inferred from detailed analysis of local depositional geometries on [[Reflection configuration patterns|seismic reflection profiles]]. On the seismic reflection profile schematic in [[:file:sedimentary-basin-analysis_fig4-27.png|Figure 8]]<ref name=ch04r6>Armentrout, J. M., 1987, Integration of biostratigraphy and seismic stratigraphy: Pliocene–Pleistocene, Gulf of Mexico: Proceedings, Gulf Coast Section SEPM 8th Annual Research Conference, p. 6–14.</ref> clinoforms 1-5 [[pinch out]] with [http://homepage.ufp.pt/biblioteca/Seismic/Pages/Page22.htm toplap] against a common horizon, suggesting oblique clinoforms.<ref name=ch04r68>Mitchum, R., M., Jr., 1977, [http://archives.datapages.com/data/specpubs/seismic1/data/a165/a165/0001/0200/0205.htm Seismic stratigraphy and global changes in sea level, 11: Glossary of terms used in seismic stratigraphy], in Seismic Stratigraphy—Applications in Hydrocarbon Exploration: [http://store.aapg.org/detail.aspx?id=1157 AAPG Memoir 26], p. 205–212.</ref> These oblique [http://unterm.un.org/DGAACS/unterm.nsf/8fa942046ff7601c85256983007ca4d8/6d701a3f58b3c00d852570d70052c711?OpenDocument clinoforms] can be interpreted as forming when sediment supply exceeds the accommodation space and causes shelf-margin [[Depocenter#Sediment_supply_rate_and_facies_patterns|progradation]]; sea level falls at the same rate as subsidence, completely bypassing the shelf with no accumulation of seismic-scale [http://www.merriam-webster.com/dictionary/topset%20beds topset] beds. Clinoforms 6 and 7 are sigmoidal<ref name=ch04r68 /> These can be interpreted as sediment supply exceeding accommodation space, forcing progradation but with subsidence exceeding the relative change in sea level and consequent accumulation of topset beds. The change from no topset beds to [[Depocenter#Sediment_supply_rate_and_facies_patterns|aggradational]] topset beds indicates a turnaround from apparent still-stand to apparent rise in sea level at the site of deposition.

==Time significance of seismic reflections==

==Time significance of seismic reflections==