Understanding Sediment Dispersion along the Continental Margin
This content explores the influences and types of sediment dispersion systems along the continental margin. Processes affecting sediment supply, depositional environments, and different dispersal systems like Estuarine Accumulations Dominated and Marine Dispersal Dominated are discussed. Walsh and Nittrouer's research from 2009 provides insights into how sediment loads behave in various scenarios.
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Christina Neal, AVO/USGS. Continental Margin Sediment Dispersion Tom Moore, NOAA Restoration Center
Sediment Dispersion Influences 1) Processes that effect sediment supply - precipitation - terrestrial morphology - drainage-basin elevation - vegetation 2) Character of the depositional environments - shelf width - wave height - sediment supply - tidal range - size and shape of the draining basin
Types of Dispersal Systems * 1) Estuarine Accumulations Dominated (EAD) 2) Proximal Accumulation Dominated (PAD) 3) Subaqueous Delta Clinoform (SDC) 4) Marine Dispersal Dominated (MDD) 5) Canyon Captured (CC) *Walsh and Nittrouer (2009)
Estuarine Accumulations Dominated (EAD) Simplest scenario of marine dispersal Low sediment loads contained in unfilled estuaries Irrespective of other characteristics (shelf width, waves, or tides, most river sediments accumulate within the estuaries *Walsh and Nittrouer (2009)
Proximal Accumulation Dominated (PAD) Small waves and low tidal range Majority of sediments flocculate and deposit close to the coastline Significant portion of the load also can be moved in the direction of prevailing currents Channel migration and switching are common *Walsh and Nittrouer (2009)
Subaqueous Delta Clinoform (SDC) Shelf sedimentary deposits displaced from the river sediment source Coastline is characterized by a tide-dominated delta as a result of strong tidal flow Large sediment loads and large tidal ranges *Walsh and Nittrouer (2009)
Marine Dispersal Dominated (MDD) Most river sediments dispersed on the continental margin Moderate to high waves and/or tidal ranges High sediment accumulation can be located in shelf or slope basins or in canyons *Walsh and Nittrouer (2009)
Canyon Captured (CC) Majority of sediment discharged is transported rapidly to the deep sea via a submarine canyon Narrow Shelf Widths with small tidal ranges Proximity of a submarine canyon is the most important factor in amount of transport *Walsh and Nittrouer (2009)
