Progradation

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In sedimentary geology and geomorphology, the term progradation refers to the growth of a river delta farther out into the sea over time. This occurs when the mass balance of sediment into the delta is such that the volume of incoming sediment is greater than the volume of the delta that is lost through subsidence, sea-level rise, and/or erosion.

As a result, progradation can be caused by:

  • Periods of sea-level fall which result in marine regression. This can occur during major continental glaciations within ice ages, periods during which mass anomalies cause the local geoid to rise, or due to an overall deepening of ocean basins that can often be caused by the presence of older, deeper sea floor.
  • Deposition from discrete glacial wedges that fuse together to form the rectilinear edge of the shelf.
  • Human activities. Surveys show that the increased population at the Huang He River in China has caused the progradation of its shoreline.
  • Based on studies on the Chang Jiang river it's discovered that high accretion rate around the river mouth caused by the high concentration of river-borne sediment eventually resulting in low organic content in the sediments. This high accretion then results in progradation.
  • Bed adjustment as well as regression.


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Schlumberger Oilfield Glossary