Sea Sediments

Match the type with origins

A. Cosmogenous 1. dissolved elements

B. Hydrogenous 2. erosion

C. Biogenous 3. dust from space

D. Terrogenous or 4. shells

Lithogenous

• Cosmogenous: cosmic dust

• Hydrogenous: dissolved elements such as the manganese nodules with lots of iron.

• Terrogenous/lithogenous: erosion of soil

• Biogenous: shells / living organisms

Sediment size from large to small

• Silt + clay = mud

Ooze distribution: yellow and green are silaceous (calcium has

dissolved due to pressure and cold)

Definitions

• Ooze: layer of dead organisms made from biogenous sediment

• Carbonate compensation depth (CCD) is a level in the oceans below which the rate of supply of calcium carbonate equals the rate of dissolution, such that no calcium carbonate is preserved.

Process of ooze formation

LYSOCLINE/CCD: calcium carbonate compensation depth

LYSOCLINE- RAPIDCHANGE IN THE

CALCIUM LEVELS AT DEPTHS OF ABOUT4000-5000 METERS

Sediment on continental shelves

• Calcareous biogenous sediments dominate tropical shelves.

• River-supplied sands and muds dominate temperate shelves.

• Glacial till and ice-rafted sediments dominate polar shelves.

Biogenous sediment producers

• Cocolithophores: Ca

• Foraminferans: Ca

• Diatoms: Si

• Radiolarians: Si

Ekman Grab

• Ekman Grab for soft • Bottom sampling

Hydrogenous sediments• Ferromanganese

Nodules• Hydrogenous deposits

from as a result of chemical reactions within seawater or between seawater and sediments; most known example are manganese nodules, with „growth rates“ of 5-10 mm/million yr.

• Mined for world’s manganese supply.

Glomar Challenger• 1968 - The Glomar

Challenger starts operations for the Deep-Sea Drilling Project. Over the years the OPD (Ocean Drilling Project) has drilled many sites.

• First major exploration of ocean floor sediments