Chapter 4- Marine Sediments

chalk

- lithified remains of coccolith-rich ooze -ex. White Cliffs of Southern England

ooze

- made of microscopic tests that accumulate on the deep-ocean floor, must contain at least 30% -resembles fine-grained mushy material - other 70% is fine-grained lithogenous clay

hydrogenous sediment

- sediment that is derived from the dissolved material in water.

turbidite deposits

-A sediment or rock formed from sediment deposited by turbidity currents characterized by both horizontally and vertically graded bedding.

glacial deposits

-A sedimentary deposit formed by a glacier and characterized by poor sorting

meteorite

-A stony or metallic mass of matter that has fallen to Earth's surface from outer space. -either composed of silicate rock material (called chondrites) or iron and nickel (called irons).

North Atlantic Deep Water

-Cold, dense water formed in the Arctic that flows onto the floor of the North Atlantic ocean. -Water in this deep current circulates through the global ocean, driving deep-ocean circulation and global heat transport, which, in turn, impacts global climate - very climatically sensitive

calcerous ooze

-Deposits comprised primarily of tests of foraminifers, coccoliths, and other calcareous-secreting organisms

rotary drilling

-Drilling involving the use of a long, hollow pipe with a drill bit on its end that is rotated to crush the rock around the outside and retain a cylinder of rock (a core sample) on the inside of the pipe.

siliceous ooze

-Ooze composed mostly of the hard remains of silica-containing organisms -at least 30% remains of silica organisms

limestone

-Rocks from the marine environment composed primarily of calcium carbonate

Neritic Deposits

-Sediment composed primarily of lithogenous particles and deposited relatively rapidly on the continental shelf, continental slope, and continental rise - these deposits are generally coarse grained

lysocline

-The depth in the ocean at which the pressure is high enough, and the amount of carbon dioxide in deep-ocean waters is great enough, to begin dissolving calcium carbonate

upwelling

-The movement of deep, cold, and nutrient-rich water to the surface - This stimulates biologic productivity which can increase deposition of siliceous ooze.

Sorting

-a measure of the uniformity of grain sizes and indicates the selectivity of the transportation process.

Stromatolites

-are lobate structures consisting of fine layers of carbonate that form in specific warm, shallow-water environments -Cyanobacteria produce these deposits by trapping fine sediment in mucous mats. -Other types of algae produce long filaments that bind carbonate particles together

Manganese nodules

-are rounded, hard lumps of manganese, iron, and other metals typically 5 centimeters (2 inches) in diameter up to a maximum of about 20 centimeters (8 inches). -When cut in half, they often reveal a layered structure formed by precipitation around a central nucleation object which could be anything discovered during voyage of HMS Challenger

oolites

-are small calcite spheres 2 millimeters (0.08 inch) or less in diameter that have layers like an onion and form in some shallow tropical waters where concentrations of CaCO3 are high. -are thought to precipitate around a nucleus and grow larger as they roll back and forth on beaches by wave action

micropscopic spherules

-are small globular masses. Some are composed of silicate rock material and show evidence of being formed by extraterrestrial impact events on Earth or other planets that eject small molten pieces of crust into space. -others are made of iron and nickel

turbidity currents

-are underwater avalanches that periodically move down the continental slopes and carve submarine canyons. -these currents also carry vast amounts of neritic material. -This material spreads out as deep-sea fans, comprises the continental rise, and gradually thins toward the abyssal plains

Aragonite

-composed of calcium carbonate (CaCO3), but has a different crystalline structure that is less stable and transforms into calcite over time

Sand and Gravel

-includes both rock fragments that are washed out to sea and shells of marine organisms, is mined by offshore barges using suction dredges. This material is primarily used as aggregate in concrete, - is the second largest sea floor deposit behind petroleum.

Wentworth scale of grain size

-indicates that particles can be classified as boulders, cobbles, pebbles, granules, sand, silt or clay - this is logarithmic scale

Phosphates

-occur abundantly as coatings on rocks and as nodules on the continental shelf and on banks at depths shallower than 1000 meters (3300 feet). -Concentrations of phosphates in such deposits commonly reach 30% by weight and indicate abundant biological activity in surface water above where they accumulate.

Destruction

-occurs when skeletal remains (tests) dissolve in seawater at depth. -biogenous sediment dissolves before ever reaching the sea floor; in other cases, it is dissolved before it has a chance to accumulate into deposits on the sea floor

Dilution

-occurs when the deposition of other sediments decreases the percentage of the biogenous sediment found in marine deposits -occurs most often because of the abundance of coarse-grained lithogenous material in neritic environments, so biogenous oozes are uncommon along continental margins

relict sediments

-sediments that accumulated and were left stranded when the sea level was lower than present day (about 5,000 years ago); - much of the continental shelf is blanketed with these sediments

Productivity

-the number of organisms present in the surface water above the ocean floor. Surface waters with high biologic_______ contain many living and reproducing organisms—conditions that are likely to produce biogenous sediments. Conversely, surface waters with low biologic ________ contain too few organisms to produce biogenous oozes on the ocean floor.

grain size

-the size of the grains that make up a rock, which helps to classify the type of rock

Gas Hydrates (Clathrates)

-unusually compact chemical structures made of water and natural gas. They form only when high pressures squeeze chilled water and gas molecules into an icelike solid.

quartz

A very hard mineral composed of silica, SiO2

coccoliths

Calcium carbonate scales that surround coccolithophores for protection

Wind transport

How are the majority of lithogenous particles transported into the deep-ocean?

-Mid Ocean ridges often pokes up above the CCD, even though the surrounding deep-ocean floor is below the CCD. Thus, calcareous ooze deposited on top of the mid-ocean ridge does not dissolve. However, sea floor spreading causes the newly created sea floor and the calcareous sediment on top of it to move into deeper water away from the ridge, eventually being transported below the CCD. This calcareous sediment will dissolve below the CCD unless it is covered by some deposit that is unaffected by the CCD.

How can Calcareous ooze exist below the CCD?

-When the organism dies, the individual plates (called coccoliths) disaggregate and can accumulate on the ocean floor as coccolith-rich ooze. -When this ooze lithifies over time, it forms a white deposit called chalk

How do Coccolithophores produce ooze?

- they do so as part of fecal pellets, which are produced by tiny animals that eat algae and protozoans living in the water column, digest their tissues, and excrete their hard parts. -These pellets are full of the remains of algae and protozoans from the surface waters and, though still small, are large enough to sink to the deep-ocean floor in only 10 to 15 days. -Once fecal pellets settle onto the ocean floor, the organic material in them is quickly consumed by bacteria and other microbes, releasing the indigestible, inorganic hard parts to the sediment.

How do biogenous tests fall to the ocean floor?

-If you examine the individual ocean pie charts, they show that the amount of ocean basin floor covered by calcareous ooze decreases in deeper ocean basins because they generally lie beneath the CCD

How does amount of ocean floor covered by calcareous ooze vary with ocean depth?

-At the warmer surface and in the shallow parts of the ocean, seawater is generally saturated with calcium carbonate, so calcite does not dissolve. -In the deep ocean, however, the colder water contains greater amounts of carbon dioxide, which forms carbonic acid and causes calcareous material to dissolve. The higher pressure at depth also helps speed the dissolution of calcium carbonate

How does destruction of calcium carbonate relate to ocean depth?

-lithogenous sediment tends to become finer with increasing distance from shore. -This relationship is mostly because high-energy transporting mechanisms predominate close to shore and lower energy conditions exist in the deep ocean basins.

How does distance from shore relate to size of lithogenous sediment?

-Sediment size is proportional to the energy needed to lay down a deposit. -Deposits laid down where wave action is strong (areas of high energy) may be composed primarily of larger particles—cobbles and boulders. -Fine-grained particles, on the other hand, are deposited where the energy level is low and the current speed is minimal.

How does grain size relate to energy needed to lay down a deposit?

(JOIDES) Joint Oceanographic Institutions for Deep Earth Sampling

Scientists continued to develop new technology for deep-sea drilling and sampling of seafloor sediments through the what program

Pelagic Deposits

Sediment composed primarily of fine lithogenous and biogenous particles that is deposited slowly on the deep ocean floor;

cosmogenous sediment

Sediment of extraterrestrial origin.

Calcite/ Carbonate Compensation Depth (CCD)

The depth at which the amount of calcite CaCO3 produced by the organisms in the overlying water column is equal to the amount of calcite the water column can dissolve. No calcite deposition occurs below this depth, which, in most parts of the ocean, is at a depth of 4500 meters (15,000 feet). - Increased amounts of CO2 can cause this level to rise

suspension settling

The process by which fine grained material that is being suspended in the water column slowly accumulates on the sea floor.

Paleooceanography

The study of how the ocean, atmosphere, and land have interacted in the past to produce changes in ocean chemistry, circulation, biology, and climate

Productivity, Destruction, Dilution

What 3 factors affect the distribution of biogenous sediment?

The most economically useful salts are gypsum and halite. Gypsum is used in plaster of Paris to make casts and molds and is the main component in gypsum board (wallboard or sheet rock). Halite—common table salt—is widely used for seasoning, curing, and preserving foods. - Halite is also used in industrial manufacture of chemicals

What are evaportive deposits used for?

The U.S considered manganese nodules a potential source of cobalt.

What are manganese nodules used for?

-are used in a variety of electronic, optical, magnetic, and catalytic applications. For example, rare-earth elements are used in a host of technological gadgets from cell phones and television screens to fluorescent light bulbs and batteries in electric car

What are rare-earth elements used for?

-are single-celled algae, most of which are planktonic. -produce thin plates or shields made of calcium carbonate, 20 or 30 of which overlap to produce a spherical test. - photosynthesize, so they need sunlight to live. -are really, really small. about 10 to 100 times smaller than most diatoms , which is why they are often called nannoplankton

What are some characteristics of Coccolithophores

-are single-celled protozoans, many of which are planktonic, ranging in size from microscopic to macroscopic. -do not photosynthesize, must ingest other organisms . -produce a hard calcium carbonate test in which the organism lives . -Most produce a segmented or chambered test, and all tests have a prominent opening in one end.

What are some characteristics of Foraminifers?

- are microscopic single-celled protozoans, most are also planktonic. -they often have long spikes or rays of silica protruding from their siliceous shell. -Rely on external food sources such as bacteria and other plankton. - typically display well-developed symmetry, which is why they have been described as the "living snowflakes of the sea."

What are some characteristics of Radiolarians

-Because diatoms photosynthesize, they need strong sunlight and are found only within the upper, sunlit surface waters of the ocean. =Most diatoms are free-floating, or planktonic. - they build a glass greenhouse out of silica as a protective cov-ering and live inside. -Most species have two parts to their test that fit together like a petri dish or pillbox. -The tiny tests are perforated in patterns that allow nutrients to pass in and waste products to pass out. -Where diatoms are abundant at the ocean surface, thick deposits of diatom-rich ooze can accumulate below on the ocean floor. - a diatoms test containing droplets of oil can even produce petroleum deposits in the ocean.

What are some characteristics of a Diatom

beach deposits, continental shelf deposits, turbidite deposits, and glacial deposits

What are some examples of neritic deposits?

- particles that have come from volcanic eruptions, windblown dust, and fine material that is carried by deep-ocean currents.

What are some examples of pelagic deposits.

-Most calcareous oozes contain some siliceous material and vice versa. • The abundance of clay-sized lithogenous particles throughout the world and the ease with which they are transported by winds and currents means that these particles are incorporated into every sediment type. • The composition of biogenous ooze includes up to 70% fine-grained lithogenous clays. • Most lithogenous sediment contains small percentages of biogenous particles. • There are many types of hydrogenous sediment. • Tiny amounts of cosmogenous sediment are mixed in with all other sediment types.

What are some examples of sediment mixtures?

Sand and gravel, evaporative salts, phosphorite, manganese nodules and crusts, and rare-earth elements.

What are some other resources associated with marine sediments?

Calcium Carbonate and Silica (SiO2)

What are the 2 most common compunds in biogenous sediment

coccolith ooze, foraminfer ooze, globigerina ooze( type of foram), pteropod oozes, ostracod oozes

What are the different types of calcareous ooze

-named after predominant organism diatomaceous ooze, radiolarian ooze, silicoflagellate ooze

What are the different types of siliceous ooze?

foraminifers and coccolithophores

What are the main producers of CaCO3 in biogenous ooze?

-large enough to be seen without microscope -includes shells, bones, and teeth of large organisms -Except in certain tropical beach localities where shells and coral fragments are numerous, this type of sediment is relatively rare in the marine environment, especially in deep water where fewer organisms live.

What is macroscopic biogenous sediment and what are some examples of it?

- contains particles so small that they can only be viewed through microscope. - examples include tests - much more abundant in deep ocean than macroscopic biogenous sediment

What is microscopic biogenous sediment, and what are some examples?

-Algae which are primarily aquatic, eukaryotic, photosynthetic organisms, ranging in size from microscopic single cells to large organisms like giant kelp. -Protozoans are any of a large group of single-celled, eukaryotic, usually microscopic organisms that are generally not photosynthetic.

What organisms contribute to biogenous sediment?

-Neritic (nearshore) deposits cover about one-quarter of the ocean floor, and pelagic (deep-ocean basin) deposits cover the other three-quarters.

What percentage of ocean in covered by Neritic and Pelagic deposits?

-The world ocean (combined) pie chart shows that calcareous ooze is the most dominant sediment worldwide, covering about 45% of the deep-ocean floor. The world ocean pie chart also shows that abyssal clay covers about 38% and siliceous ooze about 8% of the world ocean floor area

What percentage of the deep-ocean floor is covered by abyssal clay, calcareous ooze, and siliceous ooze.

-Glomar Challenger -(1) the age of the ocean floor increased progressively with distance from the mid-ocean ridge (2) sediment thickness increased progressively with distance from the mid-ocean ridge, (3) Earth's magnetic field polarity reversals were recorded in ocean floor rocks

What ship was used in the Deep Sea Drilling Project, and what did they discover?

Diatoms which are microscopic algae, and radiolarians which are a type of protozoan

What two organisms produce most of the silica in biogenous ooze

Integrated Ocean Drilling Program (IODP) -Chikyu

What was the ODP changed to, and what was one of their new ships called?

-usually occurs when there is a change in conditions, such as a change in temperature or pressure or the addition of chemically active fluids.

When does Precipitation occur?

Ocean Drilling Program (ODP) Joides Resolution

When the Deep Sea Drilling Project went international what was its name changed to? Additionally what was the new ship they used?

-is found on the shallower areas of the ocean floor beneath warmer surface water.

Where is calcareous ooze typically found?

Continental Margins

Where is the greatest quantity of lithogenous material found?

diatomaceous earth

a soft, fine, porous deposit that is composed mainly of the skeletons of diatoms -a soft, crumbly, porous sedimentary deposit formed from the fossil remains of diatoms. - this is actually used in a variety of products

metal sulfides

deposits that are associated with hydrothermal vents and black smokers along the mid-ocean ridge. -These deposits contain iron, nickel, copper, zinc, silver, and other metals in varying proportions. -Transported away from the mid-ocean ridge by sea floor spreading, these deposits can be found throughout the ocean floor and can even be uplifted onto continents.

evaporite minerals

deposits that form form wherever there are high evaporation rates (dry climates) accompanied by restricted open ocean circulation. ex. Halite- NaCl, Anhydrite CaSO4, Gypsum CaSO4 H2O)

Phosphorite

is a sedimentary rock consisting of various phosphate minerals containing the element phosphorus, an important plant nutrient. - used for fertilizer -occurs in the ocean at depths of less than 300 meters (1000 feet) on the continental shelf and slope in regions of upwelling and high productivit

Abyssal clay

is composed of at least 70% (by weight) fine, clay-sized particles from the continents. contain thick sequences of clay deposits composed of particles transported great distances by winds or ocean currents and deposited on the deep-ocean floor - also known as red clay for they sometimes contain oxidized iron

Methane Hydrate

most common gas hydrate in nature - is associated with increase in climate temperature

lithogenous sediment/ terrigenous sediment

sediment derived from preexisting rock material that originates on the continents or islands from erosion, volcanic eruptions, or blown dust.

biogenous sediment

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

tests

shells of microscopic organisms

tektites

spherules made of silicate rock materials - are glassy

sediment texture

the external features of clastic sediment grains including size, shape, and orientation

ice rafting

the process by which polar ice floats to sea carrying sediments that sink when the ice melts -In this process, rock particles trapped in glacial ice are carried out to sea by icebergs that break away from coastal glaciers. As the icebergs melt, lithogenous particles of many sizes are released and settle onto the ocean floor.

Petroleum and gas hydrates

what are the main energy sources associated with marine sediments?