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1. Sedimentary
Environment
BY
ABDUL BASIT
UNIVERSITY OF THE PUNJAB

2. Sedimentary Environment
 A depositional environment is a specific type of place
in which sediments are deposited, such as a stream
channel, a lake, or the bottom of the deep ocean. They
are sometimes called sedimentary environments
 The layers of sediment that accumulate in each type of
depositional environment have distinctive
characteristics that provide important information
regarding the geologic history of an area

3.  The characteristics that can be observed and measured
in a sedimentary rock to deduce its depositional
environment include its lithology (which is essentially
its rock type), its sedimentary structures, and any
fossils it may contain

4. WHY ARE DEPOSITIONAL ENVIRONMENTS
IMPORTANT?
 Knowledge of depositional environments is important
for reconstructing earth history, understanding earth
processes, and helping humans survive and prosper
on earth
 Reconstructing earth history
 By analyzing a sedimentary rock, a geologist can
deduce what was happening on earth at the place
and time the sediment was originally being deposited

5. Types of depositional
environments
 Four types of Sedimentry Environments
1. Continental
2. Transitional
3. Marine
4. Others

6. Continental sedimentry
environment
 It has further four types
a) Alluvium
b) Aeolian
c) Fluvial
d) Lacustrine

7. Alluvium
 Alluvium is drived from Latin, alluvius, which means"to
wash against“
 Alluvium is loose, unconsolidated (not cemented together
into a solid rock) soil or sediments, which has
been eroded, reshaped by water in some form, and
redeposited in a non-marine setting
 Alluvium is typically made up of a variety of materials,
including fine particles of silt and clay and larger particles
of sand and gravel.
 When this loose alluvial material is deposited or
cemented into a lithological unit, or lithified, it is called
an alluvial deposit

8. Aeolian
 Aeolian processes, also spelled eolian or æolian,
pertain to wind activity in the study
of geology and weather and specifically to the wind's
ability to shape the surface of the Earth (or
other planets)
 Winds may erode, transport, and deposit materials and
are effective agents in regions with sparse vegetation,
a lack of soil moisture and a large supply of
unconsolidated sediments
 Although water is a much more powerful eroding
force than wind, aeolian processes are important in
arid environments such as deserts

9. Fluvial
 Fluvial is a term used in and geology to refer to the
processes associated with rivers and streams and
the deposits and landforms created by them. When
the stream or rivers are associated with glaciers, ice
sheets, or ice caps, the term glaciofluvial or
fluvioglacial is used
 Fluvial processes include the motion of
sediment and erosion or deposition on the river bed

10. Lake
 A lake is an area of variable size filled with water, localized in
a basin, that is surrounded by land, apart from any river or other
outlet that serves to feed or drain the lake
 Lakes lie on land and are not part of the ocean (except for sea
lochs in Scotland and Ireland), and therefore are distinct
from lagoons, and are also larger and deeper than ponds,
though there are no official or scientific definitions
 Lakes can be contrasted with rivers or streams, which are usually
flowing. However most lakes are fed and drained by rivers and
streams
 Natural lakes are generally found in mountainous areas, rift
zones, and areas with ongoing glaciation
 Other lakes are found in endorheic basins or along the courses
of mature rivers

11. Lake
 In some parts of the world there are many lakes
because of chaotic drainage patterns left over from the
last Ice Age
 All lakes are temporary over geologic time scales, as
they will slowly fill in with sediments or spill out of the
basin containing them

12. Marine Sedimentary
Environments
 Marginal Marine Environments
 Marine Environments

13. Marginal Marine Sedimentry
Environment
 Marginal marine environments lies along the boundary
between continetal and marine depositional
environments
 A wide varity of sediments including Conglomerates,
Sand stones, Shales Carbonates and evaporites can
accumulate in these various marginal marine
environments

14. Beach & Barrier Islands
 These are shoreline deposits exposed to wave energy
and dominated by sand with marine fauna
 Barrier islands are separated from margined from the
mainland by a Lagoon
 The are commonly associated with tidal flat deposits

15. Lagoon Environment
 Lagoons are coastal bodies of water that have very
limited connection to the open ocean
 Lagoons generally develop along the coasts where
there is a wave formed barrier and are largely
protected from the power of open ocean waves
 A lagoonal succession is typically mudstone, often
organic rich with thin wave rippled sand beds

16. Estuarine Environments
 An estuary is the margined influenced portion of a
drowned valley
 A drowned valley is the seaward portion of a river
valley that becomes flooded with seawater when there
is a relative rise in sea level
 They are regions of mixing of fresh water and seawater
 Sediment supply to the estuary is from both river and
marine sources, and the processes that transport and
deposit sediments are a combination of river and wave
or tidal processes

17. Tidal Flats
 Tidal flats are formed when mud is deposited by tides
or rivers
 Tidal flats are the border of lagoons and estuarine
environments
 Tidal flats are areas of low relief, cut by meandering
tidal channels
 Laminated or rippled clay silt and fine sand may be
deposited by a tidal flat

18. Marine Environments
 Marine environments are in the seas or oceans
 Marine environments include reefs, the continental
shelf, slope, rise and abyssal plain

19. Continental Shelf
 The continental shelf is flooded edge of the continent
 It is relatively flat with a slope of less than 0.1*, shallow
less than 200m and may be up to hundreds of
kilometers wide
 Continental shelves are exposed to waves tides and
currents and are covered by sand silt mud and gravel

20. Reef Deposits
 Reefs are wave resistant, mound like structures made
of calcareous skeletons of organisms such as corals
and certain types of algae
 Most modern reefs are in warm, clear, shallow, tropical
seas between latitudes of 30o N and 30o S of equator

21. Continental Slope Deposits
 The continental slope are located seaward of the
continental shelf
 The continental slope is the steep (5-25o) drop off at
the edge of the continent
 The continental slope passes seaward into the
continental rise which has a more gradual slope

22. Continental Rise
 Continental rise located between the continental slope
and the abyssal plain
 The continental rise is the site of deposition of thick
accumulations of sediments much of which is in
submarine fans
 Deposited by turbidity currents at the base of
continental rise
 Turbidity current deposits are called turbidities are
characterized by graded bedding

23. Abyssal Plain
 Abyssal plain is the deep ocean floor
 It is basically flat, and is covered by very fine grained
sediments consisting primarily of microscopic
organisms e.g. radiolarians and diatoms
 Abyssal plain sediments may include chalk diatomite
and shale deposited over basaltic oceanic crust