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AMBIENTE SEDIMENTARIO: conjunto de procesos fsicos, qumicos y biolgicosque afectan la sedimentacin (Fraser, 1989).
Se reconocen tres sitios primarios para el depsito de sedimentos:(1) Continental, (2) Marino-marginal o transicional, y (3) Marino.
Cada uno de stos se encuentra dividido en diferentes sistemas de depsito, ascomo en una serie de ambientes y sub-ambientes asociados.
SITIO PRIMARIODE DEPSITO
SISTEMASPRINCIPALES
CONTINENTAL
FLUVIALDESRTICOLACUSTREGLACIALVOLCANICLSTICO
MARINO-MARGINAL
DELTAICOLAGUNARESTUARIO
PLAYABARRAS DE ARENAPLANICIE DE MAREAS
MARINO
PLATAFORMACARBONATADAPLATAFORMASILICICLSTICAABANICO SUBMARINOPLANICIES ABISALES
Clasificacin general de los ambientes de depsito.
http://www.geologia.uson.mx/academicos/grijalva/ambientesfluviales/introduccion.htm
http://www.geocities.com/SiliconValley/Bridge/3339/index50.html
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Factores fsicos: incluyen aspectos dinmicos como la velocidad. direccin yvariaciones en el movimiento del fluido que condicionan el medio; corrientes
de agua. oleaje, mareas. vientos. etc.. asi como los parmetros geogrficos y
climticos del mismo, como tipo de meteorizacin, clima, temperatura,
humedad, frecuencia de las heladas, precipitacin. etc.
Factores qumicos: condiciones de pH y eH del medio, la geoqumica de laroca madre y la interaccin qumica entre el sedimento y el ambiente;
principalmente en los subacuticos.
Factores biolgicos: tipo de flora y fauna y su influencia en los procesos
sedimentarios, formacin de suelos, erosin, etc., as como lascorrespondientes interacciones con el ambiente que puede motivar la
individualizacin de algn medio sedimentario.
Factores fsicos, qumicos y biolgicos que afectan la sedimentacin
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Boggs, 1995
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The concept of facies goes back to Armand Gressly (1830), who used the term to
designate rocks of different aspect within a particular stratigraphic unit. The idea of
facies sequences was emphasized by Johannes Walther (1896), and since about
1965, facies sequences of various types have been a standard part of
sedimentological interpretation.
facies are a body of rock with specified characteristics. [Reading (1996)]Ideally, a facies is a distinctive rock unit that forms under certain conditions of
sedimentation, reflecting a particular process or environment.
facies: the total textural, compositional and structuralcharacteristics of a sedimentary deposit resulting from
accumulation and modification in a particularenvironment. grain size, sorting, rounding
lithology
sedimentary structures
bedding type
http://en.wikipedia.org/wiki/Rock_unithttp://en.wikipedia.org/wiki/Rock_unit7/30/2019 Ambient Esse Destr at i Graf i A
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CHARACTERISTICS OF NON-MARINE ENVIRONMENTS USEFUL INIDENTIFICATION OF DEPOSITIONAL ENVIRONMENT
Alluvial fanlots of coarse particles, usually sandstone and conglomerate, poor sorting, deposited by
high energy floods or mudflowsFluvial (stream channel)sandstone and conglomerate, ripple marks and cross-beds, graded bedding
Fluvial (floodplain)usually plane bedding, fine-grained sand, silt, and clay,
Paludal (swamps)dominantly fine-grained, coal common
Lacustrine (lakes)beaches along edge; coarse-grained, well-sorted sandstone, sediments in lake are finer
grained, can find evaporites such as gypsum and haliteGlacialextremely poorly sorted, usually coarse material in moraines, better sorting in outwash
deposits, large cobbles may be striated
Aeolian (desert)
sand usually fine-grained, very large scale cross-bedding, well sorted, usually wellrounded and frosted, rocks may be polished and faceted (windblown)
http://dept.kent.edu/geology/ehlab/sed_environ/sed_environment.htm
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Transitional Environments
Beachsizes range from cobbles to fine sand,
well sorted and well-rounded,may be plane bedded or cross-bedded dunes
Estuary and Tidal Flatswater level rises and falls depending on tides,
ripples will stack on top of each other in opposite directions
mud drapes common, often find a mix of marine and non-marine animals,
tidal flats may have mud cracks
Lagoonmud and silt common
occasional sandy layers deposited by stormshighly bioturbated
oyster hash common
http://dept.kent.edu/geology/ehlab/sed_environ/sed_environment.htm
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Shallow marine (less than 200 meters)reef structures
limestone, dolomite, and gray shale common
sediments rich in glauconite and phosphate
Deep marine (greater than 200 meters)graded gray sandstone
interbedded with gray shale
bedded chert
Marine Environment
http://dept.kent.edu/geology/ehlab/sed_environ/sed_environment.htm
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CONTINENTAL SEDIMENTARY ENVIRONMENTS
ALLUVIAL FAN FLUVIALPALUDAL
Rock Type Breccia,conglomerate,
arkose
Conglomerate,
sandstone, siltstone,
shale
Peat, coal, black
shale, siltstone
Composition Terrigenous Terrigenous Terrigenous
Color Brown or red Brown or red Black, gray, orbrown
Grain Size Clay to gravel Clay to gravel (Finingupward)
Clay to silt
Grain Shape Angular Rounded to angular ---
Sorting Poor Variable Variable
Inorganic Sedimentary Structures Cross-bedding andgraded bedding
Asymmetrical ripples,
cross-bedding, graded
bedding, tool marks
Laminated to
massive
Organic or Biogenic SedimentaryStructures
--- Tracks, trails,burrows Root marks,
burrows
Fossils --- Rare freshwater shells,bones, plant fragments
Plant fossils, rare
freshwater shells,
bones, fish
http://facstaff.gpc.edu/~pgore/geology/historical_lab/environmentchart.htm
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TRANSITIONAL SEDIMENTARY ENVIRONMENTS
DELTA BARRIER BEACH LAGOON TIDAL FLAT
Rock Type Sandstone,siltstone, shale, coal
Quartz arenite,
coquina
Siltstone, shale,
limestone, oolitic
limestone or gypsum
Siltstone, shale,
calcilutite, dolostone
or gypsum
Composition Terrigenous Terrigenous orcarbonate
Terrigenous,
carbonate, or
evaporite
Terrigenous,
carbonate, or
evaporite
Color Brown, black, gray,
green, red
White to tan Dark gray to black Gray, brown, tan
Grain Size Clay to sand(Coarsening upward
Sand Clay to silt Clay to silt
Grain Shape --- Rounded to angular --- ---
Sorting Poor Good Poor Variable
InorganicSedimentaryStructures
Cross-bedding,
graded bedding
Cross-bedding,
symmetrical ripples
Lamination, ripples,
cross-bedding
Lamination,
mudcracks, ripples,
cross-bedding
Organic orBiogenicSedimentaryStructures
Trails, burrows Tracks, trails,
burrows
Trails, burrows Stromatolites, trails,
tracks, burrows
Fossils Plant fragments,shells
Marine shells Marine shells Marine shells
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MARINE SEDIMENTARY ENVIRONMENTS
REEFCONTINENTAL
SHELFCONTINENTAL
SLOPE AND RISEABYSSAL PLAIN
Rock Type Fossiliferouslimestone
Sandstone, shale,
siltstone, fossiliferous
limestone, oolitic
limestone
Litharenite,
siltstone, and shale
(or limestone)
Shale, chert, micrite,
chalk, diatomite
Composition Carbonate Terrigenous orcarbonate
Terrigenous or
carbonate
Terrigenous or
carbonate
Color Gray to white Gray to brown Gray, green, brown Black, white red
Grain Size Variable,frameworks, few
to no grains
Clay to sand Clay to sand Clay
Grain Shape --- --- --- ---
Sorting --- Poor to good Poor Good
InorganicSedimentaryStructures
--- Lamination, cross-
bedding
Graded bedding,
cross-bedding,
lamination, flute
marks, tool marks
(turbidites)
Lamination
Organic or BiogenicSedimentaryStructures
--- Trails, burrows Trails, burrows Trails, burrows
Fossils Corals, marine
shells
Marine shells Marine shells, rare
plant fragments
Marine shells
(mostly microscopic)
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SISTEMA FLUVIAL
Los depsitos fluviales estn constituidos por sedimentos que se acumulan apartir de la actividad de los ros y los procesos de deslizamiento por gravedadasociados. Aunque estos depsitos se estn generando actualmente bajo una
diversidad de condiciones climticas, desde desrticas hasta glaciales, sereconocen cuatro sistemas fluviales bien definidos: (1) sistema de abanicosaluviales (al luvial fans), (2) sistema de ros trenzados (braidded), (3) sistema deros mendricos (meander ing), y (4) sistema de ros anastomosados(anastomosing).
Diferentes tipos de canales dentro de los sistemas fluvialeshttp://www.geologia.uson.mx/academicos/grijalva/ambientesfluviales/introduccion.htm
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ALLUVIAL FAN DEPOSITS
Boggs, 1995
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M d i t
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Meandering stream
Walker, 1984
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D t E i t ( li )
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Boggs, 1995
Desert Environment (eolian)
Lakes
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Lakes
Boggs, 1995
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Boggs, 1995
Gl i l
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Glacial
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Boggs, 1995
D lt
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Delta
Walker, 1984
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Walker, 1984
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Lewis and McConchie, 1994
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Boggs, 1995
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Beach/ barrier bar
Walker, 1984
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Boggs, 1995
Playa
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Estuario
Boggs, 1995
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Reineck and Singh, 1980 Boggs, 1995
Lagoon
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Lagoon
Boggs, 1995
Tidal Flat
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Tidal Flat
Boggs, 1995
Marine Environment
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Marine Environment
Lewis and McConchie, 1994
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Shallow seas can be subdivided into clastic and carbonate-
dominated systems, depending mainly on sediment supply andclimatic setting
Idealized models predict a general decrease of grain size withwater depth (i.e., away from the shoreline); however, thissimple picture is complicated by a large number of factors (e.g.,
shelf bathymetry)
http://www.uic.edu/classes/geol/eaes350/
Shallow marine environments
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Walker, 1984
Shallow Carbonate marine environments
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Shallow Carbonate marine environments Shallow seas within the photic zone are the premier carbonate
factories
Carbonate platforms can cover continental shelves or
epicontinental seas, when the conditions for carbonateproduction (temperature, salinity, light conditions) are favorable
Isolated platforms (atolls) are found in shallow seas surroundedby deep water, like extinct volcanoes
http://www.uic.edu/classes/geol/eaes350/
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Lewis and McConchie, 1994
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Boggs, 1995
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http://www.uic.edu/classes/geol/eaes350/
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http://www.uic.edu/classes/geol/eaes350/
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Boggs, 1995http://www.uic.edu/classes/geol/eaes350/
Arrecifal
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Boggs, 1995
Walker, 1984
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Boggs, 1995
Talud
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Walker, 1984
Deep marine environments
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p
The continental slope is a major source of sediment for the deep sea, andis a setting where slumps can occur
Debris flows and turbidity currents are the main mechanisms of transport
from the continental slope into the deep sea; these processes can betriggered by external forcing (e.g., an earthquake) or by the slopereaching a critical state as a result of ongoing deposition
Debris-flow deposits and turbidites are often genetically related
Turbidites can be both clastic (commonly leading to the formation of
wackes) or calcareous
Pelagic sediments primarily have a biogenic origin Calcareous ooze (e.g., foraminifera) forms above the calcite compensation depth
(CCD) at ~4000 m depth
Siliceous ooze (e.g., radiolarians, diatoms) forms between the CCD and ~6000 m
depth where silica dissolves; it lithifies into cherts Hemipelagic sediments consist of fine-grained (muddy) terrigenous
material that is deposited from suspension Eolian dust is an important component (~50%) of hemipelagic (and pelagic)
facies
Black shales have a 1-15% organic-matter content and form in anoxic bottomwaters http://www.uic.edu/classes/geol/eaes350/
Abanico Submarino
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Reineck and Singh, 1980
Abanico Submarino
Turbiditas
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Turbiditas
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