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Line 20: − The lowering of sea level moves the water mass- and substrate-linked biofacies assemblages seaward—possibly far enough to place the inner neritic biofacies at the physiographic shelf/slope break. This movement causes the middle to outer neritic biofacies to shift basinward onto the upper slope of the clinoform (Figure 4-30B). The magnitude of relative sea level fluctuation, as well as the angle of the basin slope, controls how far the biofacies move across the physiographic profile. This pattern of low sea level biofacies distribution is confusing because the commonly used biofacies nomenclature is based on high sea level patterns where, by convention, the neritic biofacies are on the shelf (Figure 4-30A). During a lowstand, neritic biofacies may occur in situ on the physiographic slope. − + + +
Biofacies and changing sea level (view source)
Revision as of 19:31, 26 February 2014
, 19:31, 26 February 2014→Biofacies distribution during lowstand
==Biofacies distribution during lowstand==
==Biofacies distribution during lowstand==
[[file:sedimentary-basin-analysis_fig4-30.png|thumb|{{figure number|4-30}}After Armentrout.<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><ref name=ch04r9>Armentrout, J., M., 1996, High-resolution sequence biostratigraphy: examples from the Gulf of Mexico Plio–Pleistocene, in Howell, J., Aiken, J., eds., High Resolution [[Sequence stratigraphy]]: Innovations and Applications: The Geological Society of London Special Publication 104, p. 65–86.</ref> Copyright: Springer-Verlag, Geological Society of London.]]
[[file:sedimentary-basin-analysis_fig4-30.png|thumb|{{figure number|1}}After Armentrout.<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><ref name=ch04r9>Armentrout, J., M., 1996, High-resolution sequence biostratigraphy: examples from the Gulf of Mexico Plio–Pleistocene, in Howell, J., Aiken, J., eds., High Resolution [[Sequence stratigraphy]]: Innovations and Applications: The Geological Society of London Special Publication 104, p. 65–86.</ref> Copyright: Springer-Verlag, Geological Society of London.]]
The lowering of sea level moves the water mass- and substrate-linked biofacies assemblages seaward—possibly far enough to place the inner neritic biofacies at the physiographic shelf/slope break. This movement causes the middle to outer neritic biofacies to shift basinward onto the upper slope of the clinoform ([[:file:sedimentary-basin-analysis_fig4-30.png|Figure 1B]]). The magnitude of relative sea level fluctuation, as well as the angle of the basin slope, controls how far the biofacies move across the physiographic profile. This pattern of low sea level biofacies distribution is confusing because the commonly used biofacies nomenclature is based on high sea level patterns where, by convention, the neritic biofacies are on the shelf ([[:file:sedimentary-basin-analysis_fig4-30.png|Figure 4-1A]]). During a lowstand, neritic biofacies may occur in situ on the physiographic slope.
==Holocene GOM basin example==
==Holocene GOM basin example==