AMBIENTE SEDIMENTARIO: conjunto de procesos físicos, químicos y biológicos que afectan la sedimentación (Fraser, 1989).  Se reconocen tres sitios primarios para el depósito de sedimentos: (1) Continental, (2) Marino-marginal o transicional, y (3) Marino. Cada uno de éstos se encuentra dividido en diferentes sistemas de depósito, así como en una serie de ambientes y sub-ambientes asociados. 

SITIO PRIMARIO DE DEPÓSITO

SISTEMAS PRINCIPALES

   

CONTINENTAL

FLUVIAL DESÉRTICOLACUSTREGLACIALVOLCANICLÁSTICO

   

MARINO-MARGINAL

DELTAICOLAGUNARESTUARIOPLAYABARRAS DE ARENAPLANICIE DE MAREAS

   

MARINO

PLATAFORMA CARBONATADAPLATAFORMA SILICICLÁSTICAABANICO SUBMARINOPLANICIES ABISALES

 Clasificación general de los ambientes de depósito.

http://www.geologia.uson.mx/academicos/grijalva/ambientesfluviales/introduccion.htm

http://www.geocities.com/SiliconValley/Bridge/3339/index50.html

Factores físicos: incluyen aspectos dinámicos como la velocidad. dirección y variaciones en el movimiento del fluido que condicionan el medio; corrientes de agua. oleaje, mareas. vientos. etc.. asi como los parámetros geográficos y climáticos del mismo, como tipo de meteorización, clima, temperatura, humedad, frecuencia de las heladas, precipitación. etc.

Factores químicos: condiciones de pH y eH del medio, la geoquímica de la roca madre y la interacción química entre el sedimento y el ambiente; principalmente en los subacuáticos.

Factores biológicos: tipo de flora y fauna y su influencia en los procesos sedimentarios, formación de suelos, erosión, etc., así como las correspondientes interacciones con el ambiente que puede motivar la individualización de algún medio sedimentario.

Factores físicos, químicos y biológicos que afectan la sedimentación

Boggs, 1995

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 structural characteristics of a sedimentary deposit resulting from accumulation and modification in a particular environment.

• grain size, sorting, roundinggrain size, sorting, rounding

• lithologylithology

• sedimentary structuressedimentary structures

• bedding typebedding type

Ley Facies de Walter

Johannes Walther, states that the vertical succession of facies reflects lateral changes in environment. Conversely, it states that when a depositional environment "migrates" laterally, sediments of one depositional environment come to lie on top of another.

http://higheredbcs.wiley.com/legacy/college/levin/0471697435/chap_tut/chaps/chapter05-11.html

CHARACTERISTICS OF NON-MARINE ENVIRONMENTS USEFUL IN IDENTIFICATION OF DEPOSITIONAL ENVIRONMENT

Alluvial fan lots of coarse particles, usually sandstone and conglomerate, poor sorting, deposited by high energy floods or mudflows

Fluvial (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 halite

Glacialextremely 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 well rounded and frosted, rocks may be polished and faceted (windblown)

http://dept.kent.edu/geology/ehlab/sed_environ/sed_environment.htm

Transitional Environments

Beach sizes range from cobbles to fine sand, well sorted and well-rounded, may be plane bedded or cross-bedded dunes

Estuary and Tidal Flats water 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 storms highly bioturbated oyster hash common

http://dept.kent.edu/geology/ehlab/sed_environ/sed_environment.htm

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

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, or brown

Grain Size Clay to gravel Clay to gravel (Fining upward)

Clay to silt

Grain Shape Angular Rounded to angular ---

Sorting Poor Variable Variable

Inorganic Sedimentary Structures Cross-bedding and graded bedding

Asymmetrical ripples, cross-bedding, graded bedding, tool marks

Laminated to massive

Organic or Biogenic Sedimentary Structures

--- 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

http://facstaff.gpc.edu/~pgore/geology/historical_lab/environmentchart.htm

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 or carbonate

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

Inorganic Sedimentary Structures

Cross-bedding, graded bedding

Cross-bedding, symmetrical ripples

Lamination, ripples, cross-bedding

Lamination, mudcracks, ripples, cross-bedding

Organic or Biogenic Sedimentary Structures

Trails, burrows Tracks, trails, burrows

Trails, burrows Stromatolites, trails, tracks, burrows

Fossils Plant fragments, shells

Marine shells Marine shells Marine shells

http://facstaff.gpc.edu/~pgore/geology/historical_lab/environmentchart.htm

MARINE SEDIMENTARY ENVIRONMENTS

REEFCONTINENTAL

SHELFCONTINENTAL

SLOPE AND RISEABYSSAL PLAIN

Rock Type Fossiliferous limestone

Sandstone, shale, siltstone, fossiliferous limestone, oolitic limestone

Litharenite, siltstone, and shale (or limestone)

Shale, chert, micrite, chalk, diatomite

Composition Carbonate Terrigenous or carbonate

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

Inorganic Sedimentary Structures

--- Lamination, cross-bedding

Graded bedding, cross-bedding, lamination, flute marks, tool marks (turbidites)

Lamination

Organic or Biogenic Sedimentary Structures

--- Trails, burrows Trails, burrows Trails, burrows

Fossils Corals, marine shells

Marine shells Marine shells, rare plant fragments

Marine shells (mostly microscopic)

Boggs, 1995

SISTEMA FLUVIAL       Los depósitos fluviales están constituidos por sedimentos que se acumulan a partir de la actividad de los ríos y los procesos de deslizamiento por gravedad asociados. Aunque estos depósitos se están generando actualmente bajo una diversidad de condiciones climáticas, desde desérticas hasta glaciales, se reconocen cuatro sistemas fluviales bien definidos: (1) sistema de abanicos aluviales (alluvial fans), (2) sistema de ríos trenzados (braidded), (3) sistema de ríos meándricos (meandering), y (4) sistema de ríos anastomosados (anastomosing).

Diferentes tipos de canales dentro de los sistemas fluviales

http://www.geologia.uson.mx/academicos/grijalva/ambientesfluviales/introduccion.htm

ALLUVIAL FAN DEPOSITS

Boggs, 1995

Boggs, 1995

Walker, 1984

Boggs, 1995

Meandering stream

Walker, 1984

Walker, 1984

Boggs, 1995

Desert Environment (eolian)

Lakes

Boggs, 1995

Boggs, 1995

Glacial

Boggs, 1995

Delta

Walker, 1984

Walker, 1984

Lewis and McConchie, 1994

Boggs, 1995

Beach/ barrier bar

Walker, 1984

Boggs, 1995

Playa

Estuario

Boggs, 1995

Reineck and Singh, 1980 Boggs, 1995

Lagoon

Boggs, 1995

Tidal Flat

Boggs, 1995

Marine Environment

Lewis and McConchie, 1994

• Shallow seas can be subdivided into clastic and carbonate-dominated systems, depending mainly on sediment supply and climatic setting

• Idealized models predict a general decrease of grain size with water depth (i.e., away from the shoreline); however, this simple picture is complicated by a large number of factors (e.g., shelf bathymetry)

http://www.uic.edu/classes/geol/eaes350/

Shallow marine environments

Walker, 1984

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 carbonate production (temperature, salinity, light conditions) are favorable

• Isolated platforms (atolls) are found in shallow seas surrounded by deep water, like extinct volcanoes

http://www.uic.edu/classes/geol/eaes350/

Lewis and McConchie, 1994

Boggs, 1995

http://www.uic.edu/classes/geol/eaes350/

http://www.uic.edu/classes/geol/eaes350/

Boggs, 1995http://www.uic.edu/classes/geol/eaes350/

Boggs, 1995

Arrecifal

Walker, 1984

Walker, 1984

Boggs, 1995

Walker, 1984

Talud

Deep marine environments• The continental slope is a major source of sediment for the deep

sea, and is 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 be triggered by external forcing (e.g., an earthquake) or by the slope reaching 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

bottom waters http://www.uic.edu/classes/geol/eaes350/

Reineck and Singh, 1980

Abanico Submarino

Reineck and Singh, 1980

Turbiditas