View source for Earth:Depositional environment

{{Short description|Processes associated with the deposition of a particular type of sediment}}
[[File:Main depositional environments.svg|thumb|320px|right|A diagram of various depositional environments]]

In [[Earth:Geology|geology]], '''depositional environment''' or '''sedimentary environment''' describes the combination of physical, chemical, and biological processes associated with the [[Earth:Deposition (geology)|deposition]] of a particular type of [[Earth:Sediment|sediment]] and, therefore, the [[Earth:Sedimentary rock|rock]] types that will be formed after [[Earth:Lithification|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. [[Earth:Banded iron formation|banded iron formation]]s).

==Types of depositional environments==

[[File:Tsunami deposit environments.png|thumb|400px|Diagram to show the different depositional environments in which tsunami deposits are formed – partly after Shanmugam 2006 <ref name="Shanmugam_2006">{{Cite journal |last=Shanmugam G. |year=2006 |title=The Tsunamite Problem |url=https://www.researchgate.net/publication/229003931 |journal=Journal of Sedimentary Research |volume=6 |issue=5 |pages=718–730 |doi=10.2110/jsr.2006.073|bibcode=2006JSedR..76..718S }}</ref>]]

[[File:Araripe Basin - depositional environments and sequence stratigraphy.jpg|thumb|Depositional environmental model of the Araripe Basin formations, NE Brazil]]
'''Continental'''<ref>{{Cite web|url=https://commons.wvc.edu/rdawes/G101OCL/Basics/BscsTables/depenv.html|title=Basics—Table of Depositional Environments|website=commons.wvc.edu|access-date=2020-01-13}}</ref><ref name=":0">{{Cite journal |last1=Earle |first1=Steven |date=September 2015 |title=6.3 Depositional Environments and Sedimentary Basins – Physical Geology |url=https://opentextbc.ca/geology/chapter/6-3-depositional-environments-and-sedimentary-basins/ |journal=Physical Geology |access-date=2020-01-13}}</ref>

* {{annotated link|Earth:Aeolian processes| Aeolian}}. Often in deserts and coastal regions and well sorted, large scale cross-beds
* {{annotated link|Earth:Lacustrine deposits|Lacustrine}} – processes due to moving water, mainly lakes. Common sediments are sand, silt, and clay.

'''Transitional'''<ref name=":0" />

* {{annotated link|Astronomy:Tide}} – processes due to tidal currents, creates tidal flats (fine-grained, ripple marks, cross-beds).<ref>{{Cite web|url=https://commons.wvc.edu/rdawes/G101OCL/Basics/BscsTables/depenv.html|title=Basics—Table of Depositional Environments|website=commons.wvc.edu|access-date=2020-01-13}}</ref> Common sediments are silt and clay
* {{annotated link|Earth:Lagoon| Lagoonal}}. Little transportation, creates lagoon bottom environment. Common sediments are [[Chemistry:Carbonate|carbonate]]s (in tropical climates).
* {{annotated link|Earth:Beach}}. Caused by waves and longshore currents. Creates beaches, spits, and sandbars with the common sediments of gravel and sand.
* {{annotated link|Earth:Lake}}
'''Marine'''<ref name=":0" />

* {{annotated link|Earth:Shallow water marine environment}} – processes due to waves and tidal currents, creates shelves and slopes, lagoons. Common sediments are carbonates (in tropical climates) or sand, silt, and clay (elsewhere)
**{{annotated link|Physics:Upper shoreface}}
**{{annotated link|Earth:Lower shoreface}}
* {{annotated link|Earth:Abyssal plain|Deep water marine environment}} (abyssal plains) caused by ocean currents. Common sediments are clay, carbonate mud, silica mud.
* {{annotated link|Earth:Reef}} caused by waves and tidal currents. Also creates adjacent basins. Common sediments are carbonates.

'''Others'''
* {{annotated link|Earth:Evaporite}}
**Till – angular to rounded grains, poorly sorted, unstratified (massive)
**Outwash – ripple marks, cross-beds, similar to stream channel<ref>{{Cite web|url=https://commons.wvc.edu/rdawes/G101OCL/Basics/BscsTables/depenv.html|title=Basics—Table of Depositional Environments|website=commons.wvc.edu|access-date=2020-01-13}}</ref>

==Recognition of depositional environments in ancient sediments==

Depositional environments in ancient sediments are recognised using a combination of [[Earth:Facies|sedimentary facies]], facies associations, [[Earth:Sedimentary structures|sedimentary structures]] and [[Biology:Fossil|fossil]]s, particularly [[Biology:Trace fossil|trace fossil]] assemblages, as they indicate the environment in which they lived.

==References==
{{Reflist}}
* Harold G. Reading. 1996. ''Sedimentary Environments: Processes, Facies and Stratigraphy''. Blackwell Publishing Limited.

==External links==
* [https://web.archive.org/web/20090228095248/http://facstaff.gpc.edu/~pgore/geology/historical_lab/environmentchart.htm Sedimentary Environments Classification Charts] 
* [http://www.enotes.com/earth-science/depositional-environments Depositional environments on e-notes]

[[Category:Sedimentology]]
[[Category:Deposition (geology)]]

{{Sourceattribution|Depositional environment}}