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Earth and Space Sciences · Glossary

What is Parasequence and flooding surface?

Also known as: parasequence · flooding surface

Definition 16.8 University Earth and Space Sciences — Year 3 · Chapter 16 — Sequence Stratigraphy

A parasequence is a relatively conformable succession of genetically related beds bounded by flooding surfaces, in which the water shallows upward: on a wave-dominated coast, offshore mud passes up into lower and upper shoreface sand and beach. A flooding surface is a surface across which deeper-water facies abruptly overlie shallower ones, with evidence of a sudden deepening.

Three parasequences stacked three ways, drawn as grain-size logs (width to the right means coarser). Each parasequence coarsens upward from offshore mud to shoreface sand and ends at a flooding surface (FS); the top of each is coarser than the one below when the stack progrades, the same when it aggrades, finer when it retrogrades.
Three parasequences stacked three ways, drawn as grain-size logs (width to the right means coarser). Each parasequence coarsens upward from offshore mud to shoreface sand and ends at a flooding surface (FS); the top of each is coarser than the one below when the stack progrades, the same when it aggrades, finer when it retrogrades.
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