Oceanography: Chapter 4 (Marine Sediments)

What are the four types of Neritic Lithogenous Sediments?

1. Beach Deposits 2. Continental Shelf 3. Turbidite Deposits 4. Glacial Deposits

Metal sulphide deposites contain what 6 things?

1. Iron 2. Nickel 3. Copper 4. Zinc 5. Silver 6. Other materials

What four types of minerals precipitate directly from sea water?

1. Manganese Nodules 2. Phosphates 3. Carbonates 4. Metal sulphides

What five pieces of evidence provide clues of our Earth's history?

1. Marine organism distribution 2. Ocean floor movements 3. Ocean circulation 4. Climate change 5. Global extinction

Distribution of sediments depends on what three processes?

1. Productivity 2. Destruction 3. Dilution

Where are distributions of Neritic and Pelagic deposits controlled?

1. Proximity to sources of lithogenous sediments 2. Productivity of microscopic marine organisms 3. Depth of water 4. Sea floor features

Pelagic lithogenous sediments comes from what three things?

1. Volcanic ash (eruptions) 2. Wind blown dust 3. Fine grained material transported by deep ocean currents

Neritic sediments cover approximately how much of the sea floor?

1/4

Pelagic sediments cover approximately how much of the sea floor?

3/4

What do biogenous materials (ooze) consist of?

30% skeletal debris, 70% inorganic mud particles.

What do marine sediments provide?

A variety of important resources.

Where are hydrothermal vents and black smokers found?

Along the mid-ocean ridge.

Where is the greatest quantity of Lithogenous material found?

Around continental margins.

What are abyssal clays composed of?

At least 70%, fine, clay sized particles from the continents.

Biogenous deposits consist of what two Oozes?

Calcareous Oozes (Calcium Carbonate) and Siliceous Oozes (Silica)

What is CCD?

Calcite Compensation Depth is the point at which all calcite dissolves.

Where are you more likely to find coarse lithogenous sediments as opposed to fine lithogenous sediments?

Coarser sediments are closer to shore and finer are father away.

Define Rotary Drilling

Collects deep ocean sediment cores.

What are the two modern explorations of the ocean?

Cores and Rotary Drilling.

Where are Pelagic deposits found?

Deep water.

Lithogenous

Derived from land (small particles eroded from land; also called terrigenous; produced by weathering.

Biogenous

Derived from organisms.

Cosmogenous

Derived from outer space.

Hydrogenous (Authigenic)

Derived from water.

What happens to Calcareous oozes in deep water (Pelagic Deposits)?

Destruction varies with depth and temperature of water; depth speeds dissolution; CCD is reached

What do marine sediments consist of?

Eroded particles and fragments of dirt, dust and other debris.

Where are phosphates economically useful?

Fertilizers.

What are Pelagic Deposits?

Fine grained material that accumulates slowly on deep ocean floors.

Calcareous oozes break down into what two divisions?

Foraminifers (animal) and Coccolithophores (plant)

How is cosmogenous sediment produced?

From materials originating in outer space

What is one of the most important sediment properties?

Grain size.

What two minerals are considered evaporates?

Halite (table salt) and Gypsum

Define Cores

Hollow steel tubes collect sediment columns.

What are metal sulphides associated with?

Hydrothermal vents and black smokers.

What are glacial deposits?

Located in high latitude environments (currently forming by ice rafting).

What is the main ingredient in lithogenous sediments?

Mainly mineral quartz (SiO2).

What do beach deposits consist of?

Mainly wave-deposited quart-rich sands.

Where would we find clues to the origin of sediments?

Mineral composition and texture (size and shape).

Why is abyssal clay red?

Oxidized Iron (FE).

What is the study of how ocean, atmosphere, and land interactions have produced changes in ocean chemistry, circulation, biology, and climate.

Paleoceanography.

Marine sediments have been used to study what?

Past climate, geology, and biology.

Diatoms

Photosynthesize; require strong sun; nutrients allowed in through pores, and waste out; used in many products.

Siliceous Oozes break down into what two divisions?

Radiolarians (animal) and Diatoms (plant)

Coccolithophores (animal)

Range small to large; ingest organisms for food.

What does the continental shelf consist of?

Relict sediment, covering 70% of the world's continental shelf.

What do sediments over time turn into?

Rock - found in the world's tallest mountains.

How are metal sulphide deposits transported?

Sea floor spreading.

Microscopic

Seen under a microscope (tiny shells)

Where are Neritic deposits found?

Shallow water.

What happens to Silicious oozes in deep water (Pelagic Deposits)?

Silica dissolves slowly at all depths; limited amounts of silica; accumulation in high productivity zones.

How are Lithogenous sediments carried to the ocean?

Streams, wind, glaciers, and gravity.

A change in these two conditions allows for precipitation.

Temperature and pressure

What are turbidite deposits?

Underwater avalanches; forms submarine canyons; spreads to form "fans"; consists of graded bedding.

Macroscopic

Visible to the naked eye (teeth, bones, shells).

How is grain size classified?

Wentworth scale of grain size.

When is abyssal clay most likely to be abundant?

When other sediments are absent.

Radiolarians (animal)

glass-like exoskeleton; wide variety of patterns; gathers food through pores.

Foraminifers (plant)

microscopic algae; photosynthesize; spherical shell; forms chalk when dies.

What are Evaporates?

minerals that form when sea water evaporates.