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Sedimentation and StratigraphyGeology 5142
Dr. Thieme
Lecture 11: Facies and
Environments of Deposition
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Facies
Sedimentary rocks or rockcharacteristics which indicate a
particular depositional environment
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Walther's Law
The vertical succession of facies in astratigraphic column through timecorresponds to a lateral migration of those
facies over space (also referred to as-
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Facies
Different sediments accumulate adjacentto one another at the same time
Sediment facies (lithofacies) differ in
those characteristics which indicate thedepositional environment
physical (i.e. sedimentological) chemical (salinity, pH, etc...)
The changes between adjacent lithofacies
tend to be gradual
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Lithofacies
Lithofacies descriptions should include
sedimentary structures
dimensions (particularly thickness)
biogenic content (ooids, peloids, shells,
plant remains, etc... ) and its physicalcondition
composition (minerals, rocks, other sedparticles)
grain size
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Biofacies, Ichnofacies
Facies may also be identified anddescribed based upon:
the latter are most likely to directly
coincide with the lithofacies identified
Trace fossils present in the rock
(ichnofacies)
Fauna and/or flora present at the timeand place of deposition (biofacies)
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Facies Models
general enough to indicate depositionalenvironment, but
specific enough to be applied in theinterpretation of stratigraphic sections
typically combine lithofacies, ichnofacies,
and biofacies (where applicable) often define a lithofacies association
channel lag / overbank / buried soil are all
associated with "meandering stream" facies
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Transgression (Onlap)
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Regression (Offlap)
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Depositional Environment
A geographic setting where sedimentis accumulating
Determines the nature of thesediments that accumulate (grain
size, grain shape, etc.)
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Sedimentary Environments
Transitional (shoreline) Tidal flats
Lagoons Deltas
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Transitional (Shoreline) Environments
Sedimentary structures tell us where we are on
the transect from mean high water across theshoreface to offshore depositional environments
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Calcite Compensation Depth (CCD)
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Photic Zone -Photosynthesis bymarine plants andalgae in the upper
part of the watercolumn providesfood for organismsthat build shells and
skeletons depositedin limestones on thesea floor.
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