prof. abdulkader m. abed university of jordan 20/11 carbonate depositional environments abdulkader...

PROF. ABDULKADER M. ABED UNPROF. ABDULKADER M. ABED UNIVERSITY OF JORDAN 20/11IVERSITY OF JORDAN 20/11

CARBONATE DEPOSITIONAL CARBONATE DEPOSITIONAL ENVIRONMENTSENVIRONMENTS

Abdulkader M. AbedAbdulkader M. Abed

University of JordanUniversity of Jordan

[email protected]@ju.edu.jo


Depositional Environment are Depositional Environment are divided into:divided into:

1. Non – marine env.1. Non – marine env.LacustrineLacustrine

Calcrete=CalicheCalcrete=Caliche2. Marine env.2. Marine env.

Carbonate platformCarbonate platformIntertidal-supraidalIntertidal-supraidal

LagoonalLagoonal


Non-Marine environmentsNon-Marine environments1. 1. Lacustrine limestoneLacustrine limestone

Open lakesOpen lakesClosed lakesClosed lakes

Carbonate deposition can beCarbonate deposition can be1. Inorganic1. Inorganic

2.Algal/microbial2.Algal/microbial3. skeletal sands3. skeletal sands


Inorganic limestonesInorganic limestonesChemical precipitation due to Chemical precipitation due to carbonate saturation either by carbonate saturation either by

evaporation or due to loss of CO2 evaporation or due to loss of CO2 by photosynthesis or P/T changes.by photosynthesis or P/T changes.

Lime mud precipitatesLime mud precipitates..In agitated lakes ooids can formIn agitated lakes ooids can form

Aragonite, H Mg, L Mg calcite and Aragonite, H Mg, L Mg calcite and dolomite, all can form depending on dolomite, all can form depending on

the Mg/Ca ratio.the Mg/Ca ratio.


Algal/microbial limestonesAlgal/microbial limestonesLime mud formsLime mud forms by by

algae, cyanobacteria,algae, cyanobacteria,microbes and phtoplankton blooms.microbes and phtoplankton blooms.Cyanobacteria forms stromatolites, Cyanobacteria forms stromatolites,

e.g. Great Salt Lake, USA.e.g. Great Salt Lake, USA.Oncoids also, e.g. Lake Constance, Oncoids also, e.g. Lake Constance,

SwitzerlandSwitzerland


Skeletal sandsSkeletal sandsThese represent the fossis and These represent the fossis and fossil fragments livinf in lakes fossil fragments livinf in lakes

like Chara (green alagae), like Chara (green alagae), bivalves and gastropods.bivalves and gastropods.


Lacustrine FaciesLacustrine FaciesLike marine facies:Like marine facies:

ooids and stromatolite (reefs) near shore in ooids and stromatolite (reefs) near shore in agitated wateragitated water

Lime mud further inside in the deeper parts Lime mud further inside in the deeper parts of the lake.of the lake.

Sediments are usually laminated Sediments are usually laminated rhythmically , possibly seasonally,rhythmically , possibly seasonally,

laminae consists of carbonates followed by laminae consists of carbonates followed by organic matter laminaeorganic matter laminae

Closed lakes like the Dead Sea can deposit Closed lakes like the Dead Sea can deposit

evaporitesevaporites


2. Non-Marine2. Non-MarineCalcrete = calicheCalcrete = caliche

Precipitates by descending water in the soil B Precipitates by descending water in the soil B horizonhorizon

Precipitation = 200-600 mm/y &Precipitation = 200-600 mm/y &evaporation > precipitationevaporation > precipitationcan be can be dolomite = dolocretedolomite = dolocrete

Laminated & massive calcreteLaminated & massive calcretePeloids, pisoids, plant roots making veins Peloids, pisoids, plant roots making veins

fiiled with calcitefiiled with calciteUsually does not make continuous beds like Usually does not make continuous beds like

marine depositesmarine deposites


Marine carbonates and Marine carbonates and carbonate platformscarbonate platforms

Usually produces a thick Usually produces a thick sequence of marine carbonate of sequence of marine carbonate of

shallow water environmentshallow water environment5 types of platforms can be 5 types of platforms can be

recognizedrecognized


Rimmed shelfRimmed shelf = = shallow water shallow water platform with distinct break of slope platform with distinct break of slope

into deeper water. Reef and into deeper water. Reef and carbonate sand bodies usually carbonate sand bodies usually develop along the high energy develop along the high energy

margin.margin.Behind them, Behind them, shelf lagoonshelf lagoon develop develop

with restricted water circulation.with restricted water circulation.Near the shore: tidal flats and beach Near the shore: tidal flats and beach

complex develop.complex develop.


Reef

Carbonate

sandShelf lagoonTidal flats& beaches

Rimmed shelf


Carbonate RampCarbonate RampIs a gently sloping surface with Is a gently sloping surface with

a generally high energy a generally high energy shorelines and a quiet deeper shorelines and a quiet deeper

environmentenvironment


Intertidal-Supratidal carbonatesIntertidal-Supratidal carbonatesIntertidal or tidal flats lies between Intertidal or tidal flats lies between

high and low tidehigh and low tidewhile supratidal is above high while supratidal is above high

tides.tides.Tidal flats : Lime mud but some Tidal flats : Lime mud but some

times carbonate sandtimes carbonate sandSupratidal can have evaporites like Supratidal can have evaporites like

gypsum and anhydrite, and gypsum and anhydrite, and dolomitedolomite


Supratidal IntertidalTidal flat

Subtidal

Lime mudstoneRare grainstonesRestricted fossilsFenestrate porosityMicrobial matsStromatolitesBioturbationHerringbone cross beddingMud cracks

Lime mudstoneDolomiteEvaporites

Fossil diversityCarbonate Sand Below FWWB lime mud

PROF. ABDULKADER M. ABED UNPROF. ABDULKADER M. ABED UNIVERSITY OF JORDAN 20/11IVERSITY OF JORDAN 20/11 http://www.soton.ac.uk/~imw/jpg/3PT-oolite-with-mm.jpg

Carbonate sand

PROF. ABDULKADER M. ABED UNPROF. ABDULKADER M. ABED UNIVERSITY OF JORDAN 20/11IVERSITY OF JORDAN 20/11 http://www.aoml.noaa.gov/hrd/Storm_pages/odette2003/photo.html

Carbonate sands


Lagoonal CarbonatesLagoonal CarbonatesLagoons are subtidal areas behind Lagoons are subtidal areas behind

barriers, with restricted water barriers, with restricted water bodies, different from normal open bodies, different from normal open

marine water. marine water. Lime mudtsoneLime mudtsone

low fossil diversitylow fossil diversityPelletsPellets

Abundant bioturbationAbundant bioturbationNo grainstoneNo grainstone


Conditions of Carbonate Deposition

PROF. ABDULKADER M. ABED UNPROF. ABDULKADER M. ABED UNIVERSITY OF JORDAN 20/11IVERSITY OF JORDAN 20/11http://earthsystems.uta.edu/historical_labs/3depo_environments.htm

PROF. ABDULKADER M. ABED UNPROF. ABDULKADER M. ABED UNIVERSITY OF JORDAN 20/11IVERSITY OF JORDAN 20/11 http://earthnet.bio.ns.ca/english/glossary/

Beaches and Barrier Islands

When sea level rises it sometimes floods the land faster than the beach can move inland, resulting in ponded water (the lagoon) behind the beach (now barrier island). As a result there are two beaches, one on the ocean side and one on the lagoon side.

Barrier Island

Storm washover deposits

Landwardbeach

Oceansidebeach

Transition Environments

Lagoon

PROF. ABDULKADER M. ABED UNPROF. ABDULKADER M. ABED UNIVERSITY OF JORDAN 20/11IVERSITY OF JORDAN 20/11 http://www.lcss.net/florida/tortugas.htm


REEFSREEFSA carbonate build up that posses a wave A carbonate build up that posses a wave

resistant framework constructed by resistant framework constructed by organisms.organisms.

Other related terms are:Other related terms are:Patch reef: small & circular in shapePatch reef: small & circular in shape

Fringing reef: attached to the coast with no Fringing reef: attached to the coast with no lagoonlagoon

Atoll: within the ocean and enclosing a Atoll: within the ocean and enclosing a lagoonlagoon

Bioherm: As reefBioherm: As reefBuildup: a general term for accumulated Buildup: a general term for accumulated

organisms such as reef …etcorganisms such as reef …etc

PROF. ABDULKADER M. ABED UNPROF. ABDULKADER M. ABED UNIVERSITY OF JORDAN 20/11IVERSITY OF JORDAN 20/11http://earthsystems.uta.edu/historical_labs/3depo_environments.htm

REEFS1. Warm Water

• Carbonates form only in tropical waters between 30 degrees north and south.

• The formation of highly consolidated reefs only occur where the temperature does not fall below 18°C for extended periods of time. http://www.coris.noaa.gov/about/what_are/what_are.html

3. Shallow Water• The luxurient abundance of life requires photosynthesis. If the water is too deep light is filtered out.

2. Clear Water• Usually means an absence of “turbidity”, that is clastic particles• Clastic particles block out sunlight needed for photosynthetic productivity, and clog the filter feeding apparatus of organisms.

• Inorganic carbonate precipitation requires supersaturation of the water with carbonate favored by high temperatures.

4. Agitated Water• Thus usually means wave and tidal action. Part of this is to bring in the abundant nutrients to support biological activity, and part to form specific particles such as oolites.

PROF. ABDULKADER M. ABED UNPROF. ABDULKADER M. ABED UNIVERSITY OF JORDAN 20/11IVERSITY OF JORDAN 20/11 http://geology.asu.edu/~sreynolds/glg103/sed_env_start.htm

The exceptionally clear water as seen in this reef is a requirement for

carbonate formation.


Reef-building organismsReef-building organismsRecent reefs: corals + coraline Recent reefs: corals + coraline

algaealgaeless important are sponges, less important are sponges,

serpulites, oysters and certain serpulites, oysters and certain gastropods.gastropods.

In the geological many other In the geological many other groups of organisms were groups of organisms were involved in reef buildupsinvolved in reef buildups


The reef system can be divided into The reef system can be divided into three parts:three parts:

1. Fore reef (reef front, into the 1. Fore reef (reef front, into the deeper environment)deeper environment)

2. The reef itself (the reef crest and 2. The reef itself (the reef crest and flat)flat)

3. Back reef: lagoon behind the reef.3. Back reef: lagoon behind the reef.Reefs are a good reservoir for oil Reefs are a good reservoir for oil

and gas.and gas.


Pelagic limestonesPelagic limestonesDeeper water environment in the Deeper water environment in the

open ocean > 100 m.open ocean > 100 m.Source of carbonates are planktonic Source of carbonates are planktonic

organism; e.g. foraminifera, organism; e.g. foraminifera, coccoliths, … coccoliths, …

Very little siliclastic claysVery little siliclastic claysSediments are called Sediments are called calcareous calcareous

oozeooze and after lithification become and after lithification become chalkchalk


Because the source of the sediment Because the source of the sediment s is from sea surface, then after a s is from sea surface, then after a certain depth called the certain depth called the carbonate carbonate

compensation depthcompensation depth ( (CCDCCD).).In tropical waterIn tropical water

Calcite CCD: 4500-5000mCalcite CCD: 4500-5000mAragonite CCD: <2000mAragonite CCD: <2000m

In tempertae and cooler water it is In tempertae and cooler water it is much less.much less.

prof. abdulkader m. abed university of jordan 20/11 carbonate depositional environments abdulkader...

Documents

abed university of jordan

evaporites slide

switzerland slide

marine deposites slide

quiet deeper environment

carbonate platforms

marine carbonates

carbonate saturation