GroupGroup

1.UMAR KAMAL SHAH1.UMAR KAMAL SHAH

2.UMER ZAMAN2.UMER ZAMAN

LACUSTRINE LACUSTRINE ENVIRONMENTENVIRONMENT

Land locked water bodies.Land locked water bodies.

They presently cover 1% of the They presently cover 1% of the earth surface.earth surface.

Cowardin et al. (1979) define the Cowardin et al. (1979) define the lacustrine environment as lacustrine environment as

"wetlands and deepwater habitats "wetlands and deepwater habitats situated in a topographic situated in a topographic

depression or dammed river depression or dammed river channel, lacking trees, shrubs, channel, lacking trees, shrubs,

persistent emergent plants, persistent emergent plants, mosses, or lichens with greater mosses, or lichens with greater

than 30% areal coverage. than 30% areal coverage.

LACUSTRINE ENVIRONMENTLACUSTRINE ENVIRONMENT

They may be of shallow depth or They may be of shallow depth or hundreds of meters deep.hundreds of meters deep.

They may be filled with terrigenous, They may be filled with terrigenous, carbonate or evaporitic sediments.carbonate or evaporitic sediments.

Volcanic lakes are very deep but not Volcanic lakes are very deep but not very extensive.very extensive.

RELATED ENVIRONMENTSRELATED ENVIRONMENTS

SWAMP =Saturated environment with SWAMP =Saturated environment with standing water and stand of trees.standing water and stand of trees.

MARSH= Saturated environment with MARSH= Saturated environment with grasses but lack of trees.grasses but lack of trees.

BOGS=All saturated environments that BOGS=All saturated environments that contain peat.contain peat.

CHEMISTRYCHEMISTRY

They are considered as fresh water if They are considered as fresh water if dissolved solid concentration is 5%.dissolved solid concentration is 5%.

Salinity or TDS of fresh water lake is Salinity or TDS of fresh water lake is 120ppm ,while that of sea water is 120ppm ,while that of sea water is 35000ppm.35000ppm.

CACO3 ions are most CACO3 ions are most abundant,followed by Mg,Na,K,SO4.abundant,followed by Mg,Na,K,SO4.

CHEMISTRYCHEMISTRY

On basis of oxygenOn basis of oxygen Oligotropic lakes with well Oligotropic lakes with well

oxygenated oxygen.oxygenated oxygen. Eutrophic lakes with oxygen Eutrophic lakes with oxygen

deficiency.deficiency.

TEMPERATURETEMPERATURE

In almost all except shallow lakes, a distinct In almost all except shallow lakes, a distinct fairly persistent stratification develops due fairly persistent stratification develops due to temperature variation.to temperature variation.

Warm water overlies colder water.Warm water overlies colder water. Thermocline = a zone b/w these waters Thermocline = a zone b/w these waters

where temperature changes rapidly with where temperature changes rapidly with depth.depth.

Epilimnion= warm water surface.Epilimnion= warm water surface. Hypolimnion=cold water mass below Hypolimnion=cold water mass below

thermocline.thermocline.

CIRCULATION CIRCULATION

The temperature profile actually The temperature profile actually controls the circulation in a lake.controls the circulation in a lake.

Water motion in lakes is either density Water motion in lakes is either density driven or wind driven.driven or wind driven.

If there is no stratification in the lake If there is no stratification in the lake then circulation could take place in then circulation could take place in entire lake.entire lake.

If stratification is present then it will If stratification is present then it will take place in epilimnion.take place in epilimnion.

Amictic = no wind effect covered Amictic = no wind effect covered with snow.with snow.

Monomictic= characterized by one Monomictic= characterized by one period of over turn in a year.period of over turn in a year.

Dmictic = characterized by two Dmictic = characterized by two periods of overturn in a year.periods of overturn in a year.

CHEMICAL SEDIMENTSCHEMICAL SEDIMENTS

1)Saline lakes1)Saline lakes Contain more than 5000ppm dissolved Contain more than 5000ppm dissolved

solids.solids. Associated with arid or semi arid climates.Associated with arid or semi arid climates. Na is the most abundant ionNa is the most abundant ion The sequence of minerals follow the The sequence of minerals follow the

genereal evaporite sequence.genereal evaporite sequence.

CHEMICAL SEDIMENTSCHEMICAL SEDIMENTS

2)Carbonate lakes2)Carbonate lakes Precipitation is not caused by Precipitation is not caused by

evapoation.evapoation. Not restricted to arid climates.Not restricted to arid climates. Inorganic in nature but precipitation Inorganic in nature but precipitation

is caused by biological processes.is caused by biological processes. Example gear salt lake (USA).Example gear salt lake (USA).

LACUSTRINE SEDIMENTSLACUSTRINE SEDIMENTS

Clastic lacustrine sediments can be Clastic lacustrine sediments can be classified as:classified as:

Shallow littoral sediments=mostly sandy Shallow littoral sediments=mostly sandy deposits.deposits.

Pelagic sediments=muddy sediments at Pelagic sediments=muddy sediments at the deepest parts of the basin.the deepest parts of the basin.

Palustrine env= occurs where lake Palustrine env= occurs where lake margin sediments are sub aerally margin sediments are sub aerally exposed.exposed.

LACUSTRINE SEDIMENTARY LACUSTRINE SEDIMENTARY STRUCTURESSTRUCTURES

BurrowsBurrows Ripple marksRipple marks stromatolitesstromatolites

HYDROCARBON POTENTIALHYDROCARBON POTENTIAL

Large accumulations of oil and gas Large accumulations of oil and gas trapped in rocks formed in ancient trapped in rocks formed in ancient lake systems are known to be lake systems are known to be present in wester USA and china.present in wester USA and china.

Siliciclastic rocks of lacustrine origin Siliciclastic rocks of lacustrine origin are known to contain oil,natural gas are known to contain oil,natural gas and bitumen.and bitumen.