Depositional environment

The combination of physical, chemical and biological processes associated with the deposition of a particular type of sediment

In geology, depositional environment or sedimentary environment describes the combination of physical, chemical and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will be formed after lithification, if the sediment is preserved in the rock record. In most cases the environments associated with particular rock types or associations of rock types can be matched to existing analogues. However, the further back in geological time sediments were deposited, the more likely that direct modern analogues are not available (e.g. banded iron formations).

Contents

• 
  1 Types of depositional environments
  


• 
  2 Recognition of depositional environments in ancient sediments
  


• 
  3 References
  


• 
  4 External links
  

Types of depositional environments

Diagram to show the different depositional environments in which tsunami deposits are formed - partly after Shanmugam 2006 ^[1]

Depositional environmental model of the Araripe Basin formations, NE Brazil

Continental

• Alluvial


• 
  Aeolian – Processes due to wind activity


• Fluvial


• Lacustrine

Transitional

• 
  Deltaic – Silt deposition landform at the mouth of a river


• Tidal


• 
  Lagoonal – A shallow body of water separated from a larger body of water by barrier islands or reefs


• 
  Beach – Area of loose particles at the edge of the sea or other body of water


• 
  Lake – A body of relatively still water, in a basin surrounded by land

Marine

• 
  Shallow water marine environment
  
  
  
  • 
    Upper shoreface – The portion of the seafloor that is shallow enough to be agitated by everyday wave action
  
  
  • 
    Lower shoreface – The portion of the seafloor, and the sedimentary depositional environment, that lies below the everyday wave base
  
  
  
  


• 
  Deep water marine environment – Flat area on the deep ocean floor


• 
  Reef – A bar of rock, sand, coral or similar material, lying beneath the surface of water

Others

• 
  Evaporite – A water-soluble mineral sediment formed by evaporation from an aqueous solution


• Glacial


• Volcanic


• 
  Tsunami – Sedimentary unit deposited by a tsunami

Recognition of depositional environments in ancient sediments

Depositional environments in ancient sediments are recognised using a combination of sedimentary facies, facies associations, sedimentary structures and fossils, particularly trace fossil assemblages, as they indicate the environment in which they lived.

References

1. 
   ^ Shanmugam G. (2006). "The Tsunamite Problem" (PDF). Journal of Sedimentary Research. 6: 718–730. doi:10.2110/jsr.2006.073..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output .citation q{quotes:"""""""'""'"}.mw-parser-output .citation .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .citation .cs1-lock-limited a,.mw-parser-output .citation .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .citation .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Wikisource-logo.svg/12px-Wikisource-logo.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-maint{display:none;color:#33aa33;margin-left:0.3em}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}
   

• Harold G. Reading. 1996. Sedimentary Environments: Processes, Facies and Stratigraphy. Blackwell Publishing Limited.

External links

• Sedimentary Environments Classification Charts


• Depositional environments on e-notes

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