Unit 4: Marine Sediments

The four types of neritic lithogenous deposits

- Beach deposits - Continental shelf deposits - Turbidite deposits - Glacial deposits

Qualities of pelagic sediment

- Finer-grained sediments - Deposited slowly - Has greater proportion of biogenous material

What are the four types of marine sediment classifications?

- Lithogenous (Terrigenous) - Biogenous - Hydrogenous (Authigenic) - Cosmogenous

What 3 discoveries led to the support of seafloor spreading aboard the Glomal Challenger?

- Ocean floor age increased progressively with distance from the mid-ocean ridge - Sediment thickness increased progressively with distance from the mid-ocean ridge - Earth's magnetic field polarity reversals were recorded in ocean floor rocks

Qualities of Neritic sediment

- close to land - mostly lithogenous - generally course grained - typically deposited quickly

Traits of calacerous organisms + 2 examples

- single-celled protozoans (amoeba-like) - use external food - foraminifers, coccoliths

What processes create marine sediment?

- the weathering and erosion of rocks - the activity of living organisms - volcanic eruptions - chemical processes within the water itself space

It is difficult to study ocean sediments because even "shallow" water sediments are ________.

100s of feet deep, and can be 1000s of feet deep

Very small sediment from rivers, wind-blown dust and volcanic ash that are reddish-brown to chocolate-brown in color from oxidized iron (Fe).

Abyssal clay

What was discovered by the Challenger Expedition in the 1870s?

Abyssal clay

Seafloor sediment derived from the remains of hard parts of once-living organisms

Biogenous

What type of sediment produced Dover's white cliffs?

Biogenous sediment made up from Calcareous ooze by calcium-rich minerals from organisms.

The depth at which the rate of accumulation of calcareous sediments equals the rate of dissolution of these sediments (Rate of supply = rate at which the shells dissolve) is called the ______.

CCD - Calcite/carbonate compensation depth

CCD

Calcite compensation depth (or carbonate compensation depth)

Also written as CaCO3 and forms mineral calcite.

Calcium carbonate

The two most common chemical compounds found in biogenous sediment are ______.

Calcium carbonate and silica

Seafloor sediment derived from outer space

Cosmogenous

What is the rarest type of seafloor sediment?

Cosmogenous; consists of minerals that fall from space such as: - interplanetary dust (silt and sand-sized micrometeoroids) - impact products of large asteroids and comets.

What type of sediment are manganese nodules

Hydrogenous (manganese, iron, copper, nickel, cobalt) (precipitate directly from water)

Seafloor sediment derived from the dissolved material in water

Hydrogenous (Authigenic)

The U.S National Science Foundation (NSF) formed the ________ in ______.

Joint Oceanographic Institutions for Deep Earth Sampling (JOIDES); 1963

Seafloor sediment derived from land

Lithogenous (Terrigenous)

______ is the depth at which a significant amount of CaCO2 begins to dissolve rapidly.

Lysocline

Particles of organic or inorganic matter that accumulate in a loose, unconsolidated form on the seafloor are known as _________.

Marine sediment

Why are marine sediments important to study?

Marine sediments show scientists: - Clues to Earth history - Marine organism distribution - Ocean floor movements - Ocean circulation patterns - Climate change - Global extinction events - Valuable resources sometimes can be recovered from these sediments

Shallow-water deposits found primarily on the continental shelf.

Neritic

The study of how ocean, atmosphere, and land interactions have produced changes in ocean chemistry, circulation, biology, and climate is known as ________.

Paleoceanography

Deeper-water deposits

Pelagic

What is the type of seafloor sediment most commonly found on the deep ocean floor?

Pelagic sediment - Finer-grained sediments - Deposited slowly - Has greater proportion of biogenous material

What are the 3 processes that determine the distribution of biogenous sediment?

Productivity, destruction, dilution

Also written as SiO2; hydrated form is called opal.

Silica

What is the difference between siliceous ooze and calacerous ooze?

Siliceous oozes are composed of skeletons made from opal silica Si(O2), as opposed to calcareous oozes, which are made from skeletons of calcium carbonate organisms (i.e. coccolithophores).

As a result of JOIDES, what project was initiated and what did it accomplish?

The Deep Sea Drilling Project (DSDP), confirmed the existence of seafloor spreading by collecting cores in deep water (aboard the Glomal Challenger)

What is the type of seafloor sediment found mixed in with the two common types?

The type of seafloor sediment found mixed in with terrigenous and biogenous sediment is hydrogenous. These are minerals that crystalize directly from seawater through various chemical reactions.

The destruction of CaCO3 varies with depth. (True or False?)

True

The four processes that transport lithogenous sediment are ______.

Wind (ex. dust and volcanic ash) Glaciers (ex. ice-rafted rocks) Water (ex. rivers carry broken down rock such as quarts, sand, and clay minerals from granite) Gravity (ex. turbidity currents)

Calcareous ooze will only form ______ the CCD.

above

Hydrogenous sediments are also called ______ sediments because they were formed in the place they now occupy.

authigenic

Sediment made mainly from wave-deposited quartz-rich sands is known as ______ deposit.

beach

Biogenous siliceous oozes are found ______ areas of unusually ______ biological productivity.

beneath; high

Pelagic (deep ocean) sediment is dominated by ______ and ______ oozes.

biogenous; calcareous (make up about 3/4 of the ocean floor)

Relict sediments (were deposited from 3000 to 7000 years ago and have not yet been covered by more recent deposits) are known as ______ deposits.

continental shelf

Deep, cold waters are ______ to CaCO2.

corrosive

the process of skeletal remains (tests) dissolving in seawater at depth is known as ______.

destruction

The deposition of other sediments that decrease the percentage of biogenous sediments is known as ______.

dilution

In warm, shallow ocean saturated with calcium carbonate, Calcite (calcium carbonate) ______ dissolve.

does NOT

Early exploration used ________ to study ocean sediments.

dredges, a bucket-like device that scoops up sediments from the ocean floor.

Sediment size is proportional to the ______ needed to lay down a deposit.

energy (ex. high energy carries large particles and low energy carries small particles)

Hydrogenous minerals that form when seawater evaporates and are restricted open ocean circulation are known as _____.

evaporites; heating of water; breaking H bonds and adding energy

Poorly sorted deposits that are found in the high-latitude portions of the continental shelf and are currently forming by ice rafting are known as ______ deposits.

glacial

A hollow, steel tube with a heavy weight on top that collects sediment columns (cores) is a ________.

gravity core

Modern exploration uses ________ and ________ to study ocean sediments.

gravity cores; rotary drilling

Siliceous oozes predominate at ______ latitudes and ______ zones - Cover ~__% of Earth's surface

high; upwelling; 15

Minerals that precipitate (change from the dissolved to the solid state) directly from seawater through various chemical reactions are known as ______.

hydrogenous sediment

Manganese nodules, Phosphates, Carbonates and Metal sulfides are all examples of ______.

hydrogenous sediment (precipitate directly from water)

In cool, deep ocean undersaturated with calcium carbonate, CaCO3 solubility: ______ with increasing pressure. ______ with decreasing temp. ______ with increasing CO2 concentration

increases; increases; increases

The greatest quantity of ______ sediments is found around continental margins

lithogenous; coarser sediments closer to the shore while finer sediments are farther from the shore

The two types of biogenous sediment are ______.

macroscopic and microscopic

Visible to the naked eye and can be made of shells, bones, or teeth of large organisms (rare to find).

macroscopic biogenous sediment

If a biogenous comes from biogenic ooze and contains at least 30% of biogenous test material by weight, it is known as ______.

microscopic biogenous sediment

Hydrogenous minerals that change from the dissolved to the solid state are known as ______.

precipitates; cooling of water; removal of energy

The number of organisms present in the surface water above the ocean floor is known as ______.

productivity

Technology borrowed from the offshore oil industry that can collect a large supply of deep-sea sediment cores is known as _______.

rotary drilling

Sediments lithify to form ________.

sedimentary rocks

Oceanic ridges have very little marine sediment because ________.

they are newly formed, and the sediment has not had time to accumulate.

Continental margins have large deposits of marine sediment because ______.

they are older formations with a high degree of biological activity.

Sediment composed of graded bedding, deposited by turbidity currents and make up the continental rise is known as ______ deposit.

turbidite

Pelagic lithogenous sediment include particles that have come from ______, ______, and ______.

volcanic eruptions (volcanic ash); wind-blown dust; fine-grained material transported by deep ocean currents