sedimentary structures ,sedimentary rocks ,weathering and erosion ,sediment transport mechanism ,hjulstrom curve ,types of flow of sediments ,reynold number ,froude number ,laminations ,bedding plane ,cross bedding ,herringbone structure ,ripple marks ,graded bedding ,sole marks ,mud cracks ,ball and pillow structures ,stylolites ,concretion ,nodules

1. PROCESS OF TRANSPORT AND
GENERATION OF SEDIMENTARY
STRUCTURES
AKSHAY D. RAUT
M.Sc. SEM- 3,
K.S.K.V. KACHCHH UNIVERSITY

2.  Sediment is solid material that is moved and
deposited in a new location
 Sediment can consist of rocks and minerals, as well
as remains of plants and animals.
 It can be as small as a grain of sand or as large as a
boulder.
 Sediment is produced by the weathering and
erosion of preexisting rock bodies.
 Once formed, sediment is transported to a new area
where it is deposited as layers that are subsequently
lithified to form sedimentary rocks.

3. WEATHERING
EROSION
TRANSPORT
DEPOSITION
SEDIMENTS
LITHIFICATION
SEDIMENTARY
ROCK
GENERATION OF
SEDIMENTARY ROCKS

4.  Weathering is the breakdown or
decomposition of preexisting rock body.
 Three types of Weathering
1) Physical Weathering
2) Chemical Weathering
3) Biological Weathering

8. Erosion happens when rocks and sediments
are picked up and moved to another place by
different transporting agents.
Transporting Agents involved in the process are-
 Wind
 Water
 Ice, etc.

9.  Once sediment has been eroded, it is moved
to a new location by water, wind, ice, or mass
movement.
 Sediment Transport Media
1. Water- Overland flow, channel flow
Waves, tides, ocean currents
2. Air ( small particles)
3. Ice
4. Gravity- Rock Falls
Debris flows

10.  Fluid Flow
1) Traction- Rolling over the bed surface
2) Saltation- Jumping over the bed surface
3) Suspension – Permanent transport within the fluid
4) Solution- Chemical Transport

11.  Gravity Flow
Grain Flow - Cohesionless Sediment movement
Debris Flow - Viscous sediment Movement
Liquefied Flow - over-pressured interstitial fluid movement
Density/turbidity Flow: slurry movement driven by
differential density

12.  Hjulstrom curve used to determine the Erosion,
Transportation and Deposition of sediments.

13. 1. Laminar Flow
2. Turbulent Flow
3. Transition Flow

14. 1. Laminar Flow- Sediment followed a straight path that
was parallel to the boundaries.
2. Transitional Flow- Sediment followed wavy but parallel
path that was not parallel to boundary path.
3. Turbulent Flow- Sediment followed very complex path

15. Reynolds number is used to check whether flow is laminar or
turbulent using following formula
Where,
Ρ is the density of the fluid,
V is the velocity of the fluid,
Μ is the viscosity of fluid,
L is length of the fluid
The Kind of flow depends on value of Re
If Re < 2000 the flow is Laminar
If Re > 4000 the flow is turbulent
If 2000 < Re < 4000 it is called transition flow.

16. Froude number describes different flow speed and
can be find by using following formula
Where:
V = Water velocity
D = Hydraulic depth (cross sectional area of flow / top width)
g = Gravity
When:
Fr = 1, critical flow,
Fr > 1, supsercritical flow (fast rapid flow),
Fr < 1, subcritical flow (slow flow)

17. Formed at time of sedimentation.
These can be classified on the basis of
following criteria-
A. Bedding Geometry
B. Bedding of internal Structure
C. Bedding Plane Markings
D. Deformed Structures

18. A.Bedding Geometry
1. Lamination: Beds with
thickness less than 1cm is called
laminae. They are characterised
by fine grained sediments.
2. Wavy Bedding :
Wavy bedding occurs when
mud is deposited over the
whole area of a bed of rippled
and/or cross stratified sand.

19. TERMINOLOGY OF BED
THICKNESS

20. DIFFERENT TYPES OF BEDDING OR
LAMINATIONS

21. Flaser bedding is where cross-laminated sand contains mud
streaks, usually in the ripple troughs. These are commonly
forms in relatively high energy environments
Wavy bedding is where thin-ripple cross-laminated
sandstones alternate with Mudrock are commonly forms in
environments that alternate frequently from higher to lower
energies
Lenticular bedding is where mud dominates and the cross-
laminated sand occurs in lenses. They are commonly forms in
relatively low energy environments.

22. B. Bedding of internal structures :
 Cross Bedding : When the flow has changed the
direction, the structure is known as Cross Bedding.
Cross bedding forms on a sloping surface such
as ripple marks and dunes, and allows us to interpret
that the depositing agents were water or wind.

23. Basically, two main types of cross-bedding can be
defined by the geometry and their bounding surfaces:
i. Planar or Tabular planar cross-bedding, and
ii. Trough cross-bedding.

25. Herringbone cross-bedding –
Herringbone cross-bedding is produced by
reversals of the current, causing dunes and sand-
waves to change their direction of migration.
Cross-bed dips of adjacent sets are oriented in
opposite directions

26. Ripple marks are small marine, lake or riverine
topographic features, consisting of repeating wavelike
forms with symmetrical slopes, sharp peaks and rounded
troughs.
 There are mainly two types of ripples
1. Symmetrical Ripple Marks
2. Asymmetrical Ripple Marks

29. Graded Bedding :
In Graded bedding the gran size within a bed
decreases upward. Coarse material deposited first and
finer material deposited later.
There must be repeated depositional events with
changes in precipitation of materials over time

30. C. BEDDING PLANE MARKINGS
When beds separate along bedding planes, the
surfaces produced commonly display various markings
and structures.
 Sole Marks – These are markings found on the
lower side of the beds.
Types of Sole Marks-
1. Scour Marks
2. Tool Marks

31. 1. Scour Marks- They mainly form due to current
action. They are produced by cutting action of a
current of water flowing over the bottom. E.g.. Flute
Marks
2. Tool Marks- They are produced by object carried by
the flow interacting with the bed rather the flow
itself. E.g. Grooves
Scour Marks Tool Marks

32. Surface Marks :
Markings present on the surface of beds.
Mud Cracks : This sedimentary structure forms
as muddy sediments dries and contracts.
Crack formation occurs due to reduction in
water content.
Some irregular polygonal fractures are
present on the surface of beds.

34. D. Deformation Structures –
Gravitational displacement may occur during
sedimentation or shortly there after, which deform
the depositional structure.
1. Load Cast – These are the structures produced by
sinking of heavier into lighter sediments.

35. 2. Ball and Pillow Structures –
Ball-and-pillow deformations are a result of a
physical shock that has been applied to
unconsolidated sediment. This shock causes
rupturing to occur in the sedimentary rock layer,
which induces instability. Individual lobes caused by
break off move downward, settling into the
underlying layers.
These are characterized by hemispherical or
kidney shaped masses resembling balls and pillows.

37. The Structures formed by chemical processes such as
oxidation, reduction, precipitation and evaporation, etc.
1. Stylolites- These are surfaces within a rock mass at
which mineral material has been removed by pressure
dissolution, in a process that decreases the total volume
of rock.

38. Nodules- A nodule is
generally spherical or
irregularly rounded in
shape. These are typically
solid replacement bodies of
chert or iron oxide.
Concretion- A concretion is
a hard, compact mass of
matter formed by the
precipitation of mineral
cement within the spaces
between particles