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A diagram of various depositional environments. 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.
The central area of the exhalitive massive sulfides lying above the feeder zone became progressively replaced by massive pyrrhotite-chlorite alteration. Ongoing fluid flow and precipitation in the feeder zone eventually led to its sealing and diversion of fluid flow to the ring-shaped surrounding Transition Zone (TZ) characterized by sericite ...
A contact can be formed during deposition, by the intrusion of magma, [2] or through faulting or other deformation of rock beds that brings distinct rock bodies into contact. [ 3 ] The geologic subdiscipline of stratigraphy is primarily concerned with depositional contacts, [ 4 ] while faults and shear zones are of particular interest in ...
Normally graded beds generally represent depositional environments which decrease in transport energy (rate of flow) as time passes, but these beds can also form during rapid depositional events. They are perhaps best represented in turbidite strata , where they indicate a sudden strong current that deposits heavy, coarse sediments first, with ...
Robert J. Dunham published his classification system for limestone in 1962. [2] The original Dunham classification system was developed in order to provide convenient depositional-texture based class names that focus attention on the textural properties that are most significant for interpreting the depositional environment of the rocks.
Evaporite depositional environments that meet the above conditions include: Graben areas and half-grabens within continental rift environments fed by limited riverine drainage, usually in subtropical or tropical environments Example environments at the present that match this is the Denakil Depression, Ethiopia; Death Valley, California
Ripple cross-laminae forms when deposition takes place during migration of current or wave ripples. A series of cross-laminae are produced by superimposing migrating ripples. The ripples form lateral to one another, such that the crests of vertically succeeding laminae are out of phase and appear to be advancing upslope.
When many outwash streams flow from the ice front into a lowland area they form a broad sandur, or outwash plain. [17] A sandar may hold deposits that are tens of meters thick. [ 19 ] In mountainous regions the outwash streams are confined by valley sides and deposit thick layers of sediment in linear outwash plains called valley trains. [ 17 ]