Geography Optional Notes: Oceanic Deposits Calssification

The classification of oceanic deposits can be done on the basis of Source, Sediments and Location

A. Source based Classification of Oceanic Deposits

  1. Terrigenous/Lithogenous (material eroded from land)
  2. Hydrogenous (e.g. Carbonite)
  3. Biogenous (Siliceous, Calcareous)
  4. Cosmogenous (e.g. meteorite)
  5. Vulcanous
  6. Inorganic precipitate (from Air)

B. Sediment based Classification of Oceanic Deposits

Oceanic Zones: Pelagic, Eupelagic, Mesopelagic etc.

Image Source:

  1. Pelagic (open sea, not close to the shore)
  2. Littoral (close to the shore)
  3. Hemipelagic (between littoral and pelagic)
  4. Eupelagic (uppermost part of the oceanic zone, lying above the mesopelagic zone, that receives enough sunlight to allow photosynthesis)

C. Location based Classification of Oceanic Deposits

  1. Continental
    • Littoral (land)
    • Shallow Waters (1000 fathoms depth)
    • Terrigenous (>1000 fathom depth)
  2. Neritic (Shallow Sea)
  3. Pelagic (Deep Sea)

Ocean Layers: Oceanic Zones

Lithogenous Deposits

  • Depth of deposit is according to size
  • Continental shelf has boulders
  • followed by gravel, sand, silt, clay and mud
  • Mud can be of four types:
    • Red Mud: iron oxides
    • Blue Mud: Iron + Sulfur
    • Green Mud: (Blue mud + Sea Water), has potassium silicate
    • Coral mud: coral reefs derivative
Depth Profile of Biogenous Oceanic Deposits

Depth Profile of Biogenous Deposits

Biogenous Deposits

  • These are the oceanic deposits derived from dead remains of living organisms. It can be classified into
    1. Siliceous Ooze
      • Diatoms : mostly phytoplanktons
      • Radiolarians: Single celled Protozoans
      • Most abundant in the Pacific Ocean
    2. Calcareous Ooze
      • Pteropods: marine molluscs, abundant in Indian and Atlantic Oceans
      • Globigerina: Protozoans, abundant in Pacific
      • Coccolithophores

Google the terms to understand them well enough and practice the diagrams given along with this article. These are the basics of Oceanography and must be at your fingertips. You can refer to Savindra Singh for more.

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