Sediments of the OceanSediments of the Ocean

Chapter 5Chapter 5

Sediments of the OceansSediments of the Oceans Are particles of Are particles of

organic or inorganic organic or inorganic matter that matter that accumulates in a accumulates in a loose unconsolidated loose unconsolidated formform

Originates from:Originates from:1.1. WeatheringWeathering2.2. ErosionErosion3.3. Living organismLiving organism

4.4. Volcanic eruptionsVolcanic eruptions5.5. Chemical processChemical process6.6. Outer spaceOuter space

Erosion, Transportation, Erosion, Transportation, and Depositionand Deposition

Water delivers the vast Water delivers the vast majority of particulate and majority of particulate and dissolved material to the dissolved material to the sea.sea.

Wind transports only a small Wind transports only a small fraction of the sediment fraction of the sediment reaching the oceansreaching the oceans

Glaciers: In polar regions, Glaciers: In polar regions, they deliver considerable they deliver considerable quantities of coarse quantities of coarse sediment.sediment.

Larger particles require more energy to Larger particles require more energy to be moved (fig. 5.5) be moved (fig. 5.5)

The energy is supplied by moving water The energy is supplied by moving water or wind. or wind.

The faster the water or wind, the larger The faster the water or wind, the larger size particle can be picked up. size particle can be picked up.

minerals from living organisms, minerals from living organisms, calcitecalcite from coralsfrom corals

B) B) Non-mineralsNon-minerals a. a. OrganicOrganic: contains C (carbon) and H : contains C (carbon) and H (hydrogen), (hydrogen),

Ex.:plant matter, algal matter (oil) Ex.:plant matter, algal matter (oil)

b. b. InorganicInorganic: lacks the crystalline : lacks the crystalline structure (= structure (= glassglass) ) examples: volcanic ash; the silica (SiOexamples: volcanic ash; the silica (SiO22) ) of diatom shells of diatom shells

Classifying SedimentsClassifying Sediments

TurbiditesTurbidites

Turbidity Currents: play an important Turbidity Currents: play an important role in transporting sediment to deep role in transporting sediment to deep oceanocean

Turbidity Currents are density currents: Turbidity Currents are density currents: a flowing mixture of sediment and water a flowing mixture of sediment and water which is denser than surrounding water. which is denser than surrounding water.

image of a turbidity current moving down the continental slope off image of a turbidity current moving down the continental slope off California California 

Like rivers, they seek lowest point.Like rivers, they seek lowest point. Characteristics of Turbidite deposits: Characteristics of Turbidite deposits:

graded beddinggraded bedding Turbidity currents occur Turbidity currents occur

catastrophically.catastrophically. Associated features: submarine Associated features: submarine

canyons, fans, leveescanyons, fans, levees

Calcite (calcareous) particles dissolve in Calcite (calcareous) particles dissolve in deeper ocean water. deeper ocean water.

The pteropods go first, followed by the The pteropods go first, followed by the forams, and, lastly, the coccoliths. forams, and, lastly, the coccoliths.

The water depth at which all of the The water depth at which all of the forams dissolve is called the forams dissolve is called the lysoclinelysocline. .

The water depth at which the coccoliths The water depth at which the coccoliths dissolve is called the Calcium Compensation dissolve is called the Calcium Compensation Depth, the CCD (fig. 5.9) Depth, the CCD (fig. 5.9)