Sedimentary rocks are formed through the weathering of pre-existing rocks, erosion, transportation, and deposition of sediment. Weathering occurs through physical and chemical processes that break down rock into smaller pieces. Physical weathering involves no chemical change while chemical weathering uses chemical reactions. Erosion moves the weathered debris, which is then transported by agents such as wind and water and deposited in layers in basins. Over time, the compacted and cemented layers of sediment lithify into sedimentary rocks through the process of diagenesis.

1. SEDIMENTARY
PETROLOGY
FORMATION OF SEDIMENTARY
ROCKS
By: ROLL NO. 22N0008
JOYDEEP DEB

2. CONTENTS FOR DISCUSSION:
Brief Introduction to Sedimentary Rocks
Processes involve in the formation
of sedimentary rocks
 Weathering
 Physical and Chemical Weathering
 Erosion
 Transportation and Deposition

3. SEDIMENTARY ROCKS:
 Formed from sediments like pebbles, sand etc.
 Clastic Rocks: Sandstone, Conglomerate,
Breccia
 Non-Clastic Rocks: Limestone, Dolomite
How do SEDIMENTARY ROCKS Form:
Consolidation : Diagenesis
Basin
Law of Horizontality

4. What is WEATHERING ?
 Breaking, dissolving or deformation of rock to form debris
 Occurs when Exposed to weather
 Weathering agents: Wind or Air, Water, Rain, Ice, Changes in
Temperature (Differential Heating) etc.
Types of WEATHERING:

5. PHYSICAL WEATHERING:
 No Chemical reaction.
 Agents: rain, wind, changes in temperature etc
 Less vegetation cover
 Lithic Clasts
 Clasts Vary in Size
 Differential Heating
Mountain regions undergo rapid physical weathering due to wind,
ice, and temperature changes

6. CHEMICAL WEATHERING:
 Rock is Dissolved
 Chemical reaction
 Agents
CHEMICAL WEATHERING occurs mainly through:
 Oxidation:
Example: Rusting of Iron: 4Fe + 3O2 = 2Fe2O3
 Hydrolysis:
Example: Formation of Clay Minerals from K-Feldspars
 Reaction with acids:
Example: (a) H2O (water) + CO2 = H+ + (HCO3)- (bicarbonate) = H2CO3 (Carbonic acid)
(b)
c) Albite converts to Clay Minerals

7. .
EROSION:
 Movement of Debris to locations away from the rocks.
 Accompanied by Transportation.

8. TRANSPORTATION &
DEPOSITION:
 Agents carry sediments
 At large Distance Agents lose energy
 Deposition of Sediments in basins
 Stratification
 Old and Young Beds