A lacustrine environment is a type of aquatic environment that is characterized by a large body of standing water, such as a lake. Lacustrine environments are typically low-energy environments, meaning that the water is relatively calm and there is little wave action. This allows for the deposition of fine-grained sediments, such as silt and clay. Lacustrine environments are home to a variety of plants and animals, including algae, fish, and amphibians. The types of plants and animals that live in a lacustrine environment will vary depending on the climate, the depth of the water, and the nutrient content of the water. Lacustrine environments are important for a number of reasons. They provide a habitat for a variety of plants and animals. They also help to regulate the water cycle and to prevent flooding. Lacustrine environments can also be used for recreation, such as swimming, fishing, and boating. Here are some of the characteristics of lacustrine environments: Low-energy: Lacustrine environments are typically low-energy environments, meaning that the water is relatively calm and there is little wave action. This allows for the deposition of fine-grained sediments, such as silt and clay. Variety of plants and animals: Lacustrine environments are home to a variety of plants and animals, including algae, fish, and amphibians. The types of plants and animals that live in a lacustrine environment will vary depending on the climate, the depth of the water, and the nutrient content of the water. Important for water regulation: Lacustrine environments are important for a number of reasons. They provide a habitat for a variety of plants and animals. They also help to regulate the water cycle and to prevent flooding. Used for recreation: Lacustrine environments can also be used for recreation, such as swimming, fishing, and boating. Here are some examples of lacustrine environments: Lakes: Lakes are the most common type of lacustrine environment. They are typically formed by glacial activity, volcanic activity, or tectonic activity. Oxbow lakes: Oxbow lakes are formed when a river bends and then cuts off, leaving a crescent-shaped lake behind. Crater lakes: Crater lakes are formed when a volcano erupts and collapses, leaving a depression that fills with water. Lakes can be formed in a variety of ways, but the most common are: Glacial activity: Glaciers are large masses of ice that slowly move across the land, carving out depressions as they go. When a glacier melts, the depression is filled with water, forming a lake. Glacial activity lake formationOpens in a new window www.pmfias.com Glacial activity lake formation Volcanic activity: When a volcano erupts, it can leave behind a crater that fills with water, forming a lake. Volcanic activity lake formationOpens in a new window www.nps.gov Volcanic activity lake formation Tectonic activity: Tectonic activity is the movement of the Earth's plates. When tectonic plates move, they can create cracks

1. LACUSTRINE
ENVIRONMENT

2. 1
2
Introduction
lake is an inland body of water.
Water from streams, groundwater feed lakes with water.
The sediments deposited in lakes are called lacustrine deposits.
Lakes cover about 1-2 percent of the Earth’s surface
It is sometimes referred to as ‘inland seas’ but ‘inland seas’ have
some exchange of water with open ocean whereas true lakes don’t.
Formed where water is retained in a topographical depression.
4
6
5
3

3. The study of modern lakes is referred to as limnology
Sediment accumulated in lakes are locally significant.
Lake chemistry is sensitive to climatic conditions, making them useful
indicators of past climates.
Sand and mud are the most common components of lake deposits.
Some lake deposits may also contain;
1.Economically significant quantities of oil shales,
2.evaporite minerals, limestone, uranium or iron
3.abundant fine organic matter that may be source
material for petroleum or coal
7
8
9
10
11

5. Lake
Formation

6. LAKE FORMATION
Endogenous Process Exogenous Process
Tectonic Activity
Volcanic Activity
Glaciation
Erosion &
Deposition

7. TECTONIC
ACTIVITY
 Rift and strike- slip basins are bounded by faults that cause
parts of the land surface to subside relative to the
surrounding area.
 With continued movement on the faults and hence
continued subsidence, the lake may become hundreds of
metres deep, and through time may accumulate hundreds
or even thousands of metres of sediment.
 Depressions that are related to broad subsidence of the
crust (sag basins) tend to be larger and shallower.
Continental extension
to generate rift
Strike slip with
continental crust
Intracontinental Sag
basins

8. VOLCANIC
ACTIVITY
 Volcanic activity can also create large lakes by caldera collapse and explosive
eruptions that remove large quantities of material from the Centre of a volcanic
edifice, leaving a remnant rim within which a crater lake can form.
 The crust of a hollow lava flow may collapse. The subsidence leaves behind a wide and
shallow depression in which a lake may form.
 In volcanic regions a stream of lava may flow across a valley, become solidified and thus
dam the river forming a lake.
Caldera Lakes
Types
Crater and
Caldera
Lakes
Subsidence
of a Volcanic
Land
Surface
Lava-
Blocked
Lakes

9. GLACIATION
 Glaciers Create lakes by building of natural
dams across a a valley floor through the
formation of a terminal moraine.
 Glacier can scour more deeply into the valley,
creating a depression in the valley floor &
lakes creates.
Types
Cirque
Lakes or
Tarns
Kettle
Lakes
Rock-
Hollow
Lakes
Deposition
of Glacial
Drifts
Morainic
Damming
of Valleys

10. EROSION
AND
DEPOSITION
o Karst lakes are formed as the result of a collapse of caves,
especially in water-soluble rocks such as limestone, gypsum and
dolomite.
o The deflating action of winds in deserts creates hollows. These
may reach ground water which seeps out forming small,
shallow lakes.
Types
Karst
Lake
Wind
Deflated
Lake
Barrier
lake
Ox- Bow
Lake

11. HUMAN AND
BIOLOGICAL
ACTIVITY
Man Made
lake
o Animals like beavers are particularly interesting. They
live in communities and construct dams across the
rivers with timber. Such beaver dams are quite
permanent and are found in North America.
Lake Made by
Animals
o Besides the natural lakes, man has now created artificial
lakes by erecting a concrete dam across a river valley so
that the river water can be kept back to form reservoirs.
Human activities (a lake made by
constructing a a concrete dam across a a
river valley)
Dhebar lake

12. Lake Hydrology

13. 1 2 3
From Streams the
sweet water can
accumulate into
lake and enrich the
lake. It is Main
source of water for
lake.
Rainfall contributes
much low in lake
water volume water.
Only 6% of lake
water enriched in
rainfall.
STREAMS RAINFALL
Through Ground
water seepage
water can
accumulate in lake
basin.
GROUND WATER
Supply of Water in Lake

14. 2. Hydro-Geologically
closed basin
1. Hydro-Geologically
open basin
2
Based on
inflow-
outflow for
basin

15. 1 2
water wont outflow
until it reaches spill
point
Balanced Water supply
into or out the basin
Points to remember for
Hydrogeologically Open Basin
After reaching spill
point, water level is
constant and inflow-
outflow takes place as its
own
4 Due to constant inflow
and outflow of sweet
streamwater, ground
and rainwater; salinity
or dissolved salt level
in this basin is so much
low that other basins
3

16. Inflow into basin
Spill point
Outflow from basin
Inflow = outflow
Hydrogeologically open basin

17. 1 2
This type of basin known as
endorheic lake. means the
basin of internal drainage.
points to remember for
Hydrogeologically closed basin
only inflow of basin
takes place. There is no
outflow of basin. only
outflow of the basin is
evaporation.
Soluble ions weathered
from rock and deposited in
basin. As there in no outflow
they start accumulating in
basin increses basin salinity
4 evaporation rate is high and
inflow is so low so there water
level cannot reach spill point.
3

18. Inflow
no out flow
evapo-transporation rate (if we
consider it not as outflow) > inflow
Hydrogeologically closed basin

19. Effect of
climate on
lake
salinity
In arid dry environment mainly evaporation rate is high so here due to no outflow the
closed basin waters have more salinity.
In Humid and cold areas, the evaporation rate is very much low. so here basins are
generally open basins and if it is closed the water in the basin is much less saline than
the arid one.

20. Salt water lake
Sweet water lake

21. PRECIPITAION
CARVE
so according to precipitation carve the precipitation sequence will be
Calcite Gypsum Halite

22. NEAROCEAN
LAKES
Near Ocean when a waterbody partly isolated
form Ocean. This are not actually Lake . This are
Barred ocean but as they are isolated waterbody
we will cover it.
They are connected with seawater and seawater
repeatedly replenish them. So they are deposited
as salt giants.
Production of thick succession
Shallow water
to
Deep Basin
Sallow water
to
Shallow basin
Deep water
to
Deep basin

23. 1
Shallow water
to
Shallow Basin
Here periodic overflow takes
place.
Due to this periodic overflow
when saline water enter the
basin and by evaporating it
form a salt layer. then another
saline water flow enter the
basin . it forms another
evaporite layering.
so in this setting continuous
subsidence of evaporite layer
takes place.

24. 2
Shallow water
to
Deep Basin
• Here, exists a basin which is
well below sea level but is
only partly filled with
evaporating seawater, which
is periodically replenished.
• The deposits overlying the
evaporites show deep marine
characteristics such as
turbidites.

25. 3
Deep water
to
Deep Basin
• Is a basin in which evaporite
sediments are formed at the
shallow margins and are
redeposited by gravity flows
into deeper parts of the
basin.
• Normally graded beds
generated by turbidites and
poorly sorted deposits
resulting from debris flows
are evidence of
redeposition.

26. Bull's eye pattern
Denotes long time
isolation from
ocean

27. Teardrop pattern
Denotes semi isolated
Basin

28. Lake Types

29. TYPES
Freshwater
Lake
Ephemeral
Lake
Saline
Lake
1
3
2
Based on Sedimentological view point

30. 1.Freshwater
Lake
The majority of large modern lakes
are freshwater.
Low saline water, mainly hydrologically
closed; hence low supply of dissolve ion.
They occur at latitude ranging from
equator to polar.
Wular lake, Kashmir

31. 1.Freshwater
Lake Hydrogeology of Freshwater lake
Contrast in temperature, density and chemistry of upper and lower part of the water body forms LAKE WATER
STRATIFICATION.
Upper warmer water is known as Epilimnion
Lower colder water body is known as Hypolimnion.
They are separated by a surface, called Thermocline.

32. Freshwater
Lake Hydrogeology of Freshwater lake
Epilimnion is aerobic by contact with air, in contrast hypolimnion is anaerobic part.
Organic matter deposited at lake floor, not subjected aerobic decomposition. Hence, good potential to form
coal or source rock for oil and gas.

33. Lake Margin Clastic
Deposit
Lake delta: Where River enters intO lake, the water velOcity drOps abruptly, and a delta
fOrms.
Marshy envirOnment near the lake margin,
referred tO as Palustrine envirOnment.

34. Deep Lake Facies
Away from the margins, clastic sedimentation occurs as plumes of suspended sediment and
transport by density currents. The suspended load will fall to the lake floor to form a layer of
mud.
Density currents provide mixtures of sediment and water brought in by a river or
reworked from a lake delta may flow as a turbidity current.
The deposits will be layers of sediment that grade from coarse material deposited from the
current first to finer sediment that settles out last.
Deep lake facies will consist of very finely laminated muds deposited from suspension
alternating with thin graded turbidites forming a characteristic, thinly bedded succession.

36. Varve deposits
A verve is a pair of sedimentary layers that is deposited over the course of a
single year. They are most common in high latitude areas or high altitude lakes
(i.e. glacial locations) where there is a strong contrast on seasonal conditions.
During the spring and summer, coarse sediments are deposited into the lakes
by the melt waters from nearby glaciers. During the winter, the lakes and rivers
freeze. Only the fine sediments that settle from the water column is deposited
on the lake bottom. These fine sediments are often rich in organic materials
from decaying algae. Thus, they create a much darker layer.
By counting the pairs of coarse-light layers and fine-dark layers. Geologist can
determine how long it took for a particular sedimentary sequence to develop.

37. Saline Lake

38. Saline lakes are hydrologically close and perennial, supplied by rivers
containing dissolved ions weathered from bedrock and in a climatic setting
where there are relatively high rates of evaporation.
About
saline
water
lake

39. BRACKISH WATER SALINE WATER HYPERSALINE
WATER
The salinity may vary
from 5 g/L of solutes,
which is Brackish
water.
Saline, which is
close to the
concentration of salts
in marine waters.
Hyper saline
waters, which have
values well in excess
of the concentrations
in seawater.

40. Chemistry of Saline Lake water
• The chemistry of saline lake waters is determined by the nature of the salts
dissolved from the bedrock of the catchment area of the river systems that supply
the lake. As the bedrock geology varies from placed to place so the chemical
composition of every lake is therefore unique, unlike marine waters, Which
all have the same composition of salts.
• The types and proportions of evaporite minerals formed in saline lakes are
therefore variable.
• The main ions present in modern saline lake waters are the cations sodium,
calcium and magnesium and the carbonate, chloride and sulphate
anions.

41. Soda lake Sulphate lake
Salt lakes or Chlorite
lakes
Soda lakes have brines
with high concentrations
of bicarbonate ions
called Trona.
And Sodium carbonate
minerals such as Natron
Brines have lower
concentrations of bicarbonate
but are relatively enriched in
magnesium and calcium.
Such as the Dead Sea
are similar in mineral
composition to marine
evaporites.
These minerals are not
precipitated from marine
waters and are therefore
exclusive indicators of
non-marine evaporite
deposition.
They precipitate mainly sulphate
minerals such as gypsum and
mirabilite.

43. Organisms in Saline Lake
Blue-green algae and bacteria.
Organic productivity may be high enough to
result in sedimentary successions that
contain both evaporite minerals and black
organic-rich shale.

44. Ephemeral
Lake

45. 1 Defination
Ephemeral Lakes are large bodies of water that dry out
periodically.
2 Formation
Rate of evaporation outpaces rate of precipitation in
such lakes.
Types of Lakes
1. Perennial Brine bodies( Permanent saline lakes)
2. Ephemeral salt pans(Subjected to seasonal flooding)
3
4 Areas of Formation
Mainly in desert areas ( Arid environment)

46. Alternative layer of Mud and Evaporites
Water influx is periodic; suspension fall-out producing muddy layer
during high water stage.
With further evaporation the ion concentration in the water starts to
increase to the point where precipitation of saline evaporitic minerals
occurs.
Desiccation Cracks
Evaporation of the water body gradually reduces its volume and the
area of the lake starts to shrink, leaving areas of margin exposed
where desiccation cracks may form in the mud as it dries out.
Inland Sabkhas and Desert rose
Evaporite minerals form within the sediments surrounding the
ephemeral lakes.
5
Depositional Freatures

47. CONTROLS ON LACUSTRINE DEPOSITION
•Base level determining:
A.Climate: Determining the water as well as sediment supply rates
B. tectonism: Controls the size and depth of the lake and the type as well as rate of sediment supply
Base level of lake
Basin subsidence
Initial base level
Final base level
• Accommodation space increases
If, The accumulation of sediment is
less than the basin subsidence.
• Same effect will be there for uplift of the
sill.
Basin uplift
Initial base level
Final base level • Accommodation space decreases.
with basin uplift
with mass accumulation of sediment.

48. • The fluvial input is approximately
balanced by the loss through
evaporation.
• Sensitive to climate.
• Shoreline may shift towards the
basin centre.
• May develop structure like
desiccation crack.
• Shore line can shift towards the
sill.
• Facies exabits vertical fluctuation
of lake level.
• lake level rarely reaches
threshold, as in ephemeral or
saline lakes.
• Cycle of climate change can be
inferred from the alternation of
dark coloured mudrock and
ecvaporites deposits.
• Hydrologically OPEN.
• Generally in HUMID
environment.
• Deposition at the
margin(deltas, beaches).
• Deposition from suspension
fall out and by turbidity
current.
• No fluctuation of water depth.
LAKES
Overfilled Lakes Balanced fill Lakes Underfilled Lakes

49. Recognition of
Lacustrine Facies

50. Recognition of Lacustrine Facies
 If the succession is entirely terrigenous clastic material, it is not always easy to distinguish between the deposits of a
lake and those of a low energy marine environment such as a lagoon and deep ocean basin.
The main criteria for distinguishing between lacustrine and marine facies are often the differences between the
organisms and habitats that exist in these environments.
There are a number of groups of organisms that are found only in fully marine environments: these include corals,
echinoids, brachiopods, cephalopods, graptolites and foraminifers on the other hand the more reliable indicator of
freshwater condition are algal and bacterial fossil form.
The lack of mixing of the oxygenated surface water with the lower part of the water column results in anaerobic
condition which create stratification with in the water column of the lake. It is an unique feature of the lake environment.
The bottom water of the is devoid of animals Because of that anaerobic condition, for that reason most of the
sedimentary feature’s are remain unharmed from the bioturbation but in marine environments is typically destroyed by
burrowing organisms.

51. Recognition of Lacustrine Facies
The anoxia also prevents the aerobic breakdown of organic material that settles on the lake floor, allowing the
accumulation of organic-rich sediments.
The deposits of saline and ephemeral lakes usually can be distinguished from marine facies by the chemistry of the
evaporite minerals.

52. Life in lakes and fossils in lacustrine deposits
Paleontological evidence is often a critical factor in the recognition
of ancient lacustrine facies.
Fauna commonly found in lake deposits include gastropods,
bivalves, ostracods and arthropods, sometimes occurring in
Monospecific assemblages, that is, all organisms belong to the
same species. Algae and cyanobacteria are an important component
of the ecology of lakes.
A common organism found in lake deposits are Charophytes,
algae belonging to the Chlorophyta which are seen in many ancient
lacustrine sediments in the form of calcareous encrusted stems and
spherical reproductive bodies. Charophytes are considered to be
intolerant of high salinities.
Cold, sediment-starved lakes in mountainous or polar
environments may be sites of deposition of siliceous oozes, The
origin of the silica is diatom Phytoplankton it is very abundant in
glacial lakes. These deposits are typically bright white cherty beds
that are called Diatomite's
Images of Chara in the field
Source: THE ECOLOGY OF CHAROPHYTE ALGAE
(CHARALES)1Maximiliano Barbosa, Forrest Lefler,
David E. Berthold, and H. Dail Laughinghouse IV 2

53. Cold, sediment-starved lakes in mountainous or polar environments may be
sites of deposition of siliceous oozes, The origin of the silica is diatom
Phytoplankton it is very abundant in glacial lakes. These deposits are
typically bright white cherty beds that are called Diatomite's