Oceanography chapter 4

methane hydrate

A white compact icy solid made of water and methane. The most common type of gas hydrate.

Radiolaria

An order of planktonic and benthic protozoans that possess protective coverings usually made of silica.

Coccolith

Tiny calcareous discs averaging 3 microns (0.0001 inch) in diameter that form the cell wall of coccolithophores.

Calcite

a mineral with the chemical formula CaCO3

rotary drilling

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

The distribution of biogenous sediment on the ocean floor depends on three fundamental processes

productivity, destruction, and dilution

cosmogenous sediment

sediment derived from outer space;

Silica

silicon dioxide (SiO2)

carbonate minerals

those that contain CO3 in their chemical formula

upwelling

where deep-ocean water comes to the surface and supplies nutrients that stimulate high rates of biological productivity

Chikyu

"Planet Earth" - state of the art drill ship that is capable of drilling deeper at sea that any other science drilling vessel - up to 7000 m

cores

(1) the deep, central layer of Earth, composed primarily of iron and nickel. it is subdivide into a liquid outer core 2270 km thick and a solid inner core with a radius of 1216 km. (2) a cylinder of sediment and/or rock material usually obtained by drilling.

ice rafting

(1) the movement of trapped sediment within or on top of ice by flotation. (2) the forcing of some ice flows on top of others as a result of expanding floes running out of open water on which to float as they grow.

metal sulfide

A compound containing one or more metals and sulfur.

manganese nodule

A concretionary lump containing oxides of manganese, iron, copper, cobalt, and nickel found scattered over the ocean floor.

Siliceous

A condition of containing abundant silica (SiO2)

diatom

A member of the class Bacillariophyceae of algae that possesses a wall of overlapping silica valves.

metor

a bright trail or streak that appears in the sky when a meteoroid is heated to incandescence by friction with earth's atmosphere; also called a falling or shooting star

Stromatolites

a calcium carbonate sedimentary structure in which algal assemblages trap sediment and bind it into forms that are often dome shaped. They are known to form only in shallow-water environments

Calcium carbonate

a chalk-like substance secreted by many organisms in the form of coverings or skeletal structures

limestones

a class of sedimentary rocks composed of at least 80% carbonates of calcium or magnesium. may be either biogenous or hydrogenous

spherule

a cosmogenous microscopic globular mass composed of silicate rock material (tektites) or of iron and nickel

diatomaceous earth

a deposit composed primarily of the tests of diatoms mixed with class (diatomite, tripolite, kieselguhr)

Oolite

a deposit formed a small spheres from 0.25 to 2 mm to diamater. each one is composed of concentric layers of calcite

Integrated Ocean Drilling Program (IODP)

a drilling program that replaced ODP in 2003 with a new drill ship that has riser technology, enabling cores to be collected from deep within Earth's interior

aragonite

a form of CaCO3 that is less common and less stable than calcite. Pteropod shells are usually composed of this

gravity corer

a hollow steel tube with a heavy weight on top would be used to collect the first cores

gas hydrates

a lattice-like compound composed of water and natural gas (usually methane) formed in high-pressure and low-temperature environments such as those found in deep-ocean sediments. also known as clathrates because of their cage-like chemical structure

Wentworth scale of grain size

a logarithmic scale for size classification of sediment particles

coccolithophore

a microscopic planktonic form of algae encased by a covering composed of calcareous discs (coccoliths)

petroleum

a naturally occurring liquid hydrocarbon;

ooze

a pelagic sediment containing at least 30% skeletal remains of pelagic organzisms, the balance being clay minerals. further defined by the chemical composition of the organic remains (siliceous or calcareous) and by their characteristics organisms (e.g. diatomaceous ooze, foraminifer ooze).

protozoa

a phylum of one-celled animals with nuclear material confined within a nuclear sheath

weathering

a process by which rocks are broken down by chemical and mechanical means

Ocean Drilling Program (ODP)

a program that replaced the Deep Sea Drilling Project in 1983, focusing on drilling the continental margins using the drill ship JOIDES Resolution

Deep Sea Drilling Project (DSDP)

a sea floor drilling program initiated in 1968 that was designed to obtain cores from the deep sea; it was the predecessor to the Ocean Drilling Program (ODP) and the Integrated Ocean Drilling Program (IODP)

turbidite deposits

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

glacial deposit

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

evaporite minerals

a sedimentary deposit that is left behind when water evaporates

phosphorite

a sedimentary rock composed primarily of phosphate minerals

chalk

a soft, compact form of calcite, generally gray-white or yellow-white in color and derived chiefly from microscopic fossils

meteorite

a stony or metallic mass of matter that has fallen to earth's surface from outer space; the debris from meteors

precipitate

a substance that is formed chemically whenever dissolved material change from existing in the dissolved state to existing in the solid state

Sorting

a texture of sediments, where a well-sorted sediment is characterized by having great uniformity of grain sizes

quartz

a very hard mineral composed of silica, SiO2. one of the most abundant, chemically stable, and durable minerals in earth's crust

salt deposit

an evaporative deposit composed of precipitated salts from seawater such as halite, gypsum, and in some cases calcite.

foraminifer

an order of planktonic and benthic protozoans that possess protective coverings, usually composed of calcium carbonate.

phosphates

any of a number of phorphorus-bearing compounds

pelagic deposits

are found in the deep-ocean basin and are typically fine-grained

Neritic deposits

are found on continental shelves and in shallow water near islands; these deposits are generally coarse grained.

Examples of lithogenous neritic deposits

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

dredge

bucket-like device that was used to scoop up sediment from the deep ocean floor. It didn't work correctly and disturbed the sediment and could only gather samples from the surface of the ocean floor.

microscopic biogenous sediment

contains particles so small they can be seen only through a microscope; produce tiny shells called tests that begin to sink after the organisms die and continually rain down in great numbers onto the ocean floor

Abyssal clay

deep-ocean (oceanic) deposits containing less than 30% biogenous sediment. Often oxidized and red in color, this commonly termed red clay

Calcareous

deposits comprised primarily of tests of foraminifers, coccoliths, and other calcareous-secreting organisms; containing calcium carbonate

planktonic

free floating bacteria such as in saliva or sulcular fluid

clues to sediment origin are found

in its mineral composition and its texture

Macroscopic biogenous sediment

large enough to be seen without the aid of a microscope and includes shells, bones, and teeth of large organisms.

Phosphorus-bearing compounds

occur abundantly as coating on rocks and as nodules on the continental shelf and on banks at depths shallower than 1000 m.

destruction

occurs when skeletal remains (tests) dissolve in seawater at depth.

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.

sediment

particles of organic or inorganic origin that accumulate in loose form

pelagic lithogenous sediment includes

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

nannoplankton

plankton less than 50 microns (0.002 inch) in length that cannot be captured in a plankton net and must be removed from the water by centrifuge or special microfilters

algae

primarily aquatic, eukaryotic, photosynthetic organisms that have no root, stem, or leaf systems. can be micro or macro - scopic

Lithogenous Sediment

sediment composed of mineral grains derived from the weathering of rock material and transported to the ocean by various mechanisms of transport, including running water, gravity, the movement of ice and wind.

Biogenous sediment

sediment containing material produced by plants or animals, such as coral reefs, shell fragments, and housings of diatoms, radiolarians, foraminifers, and coccolithophores; components can be either

terrigenous sediment

sediment produced from or of thee earth. also called lithogenous sediment

Hydrogenous sediment

sediment that forms from precipitation from ocean water or ion exchange between existing sediment and ocean water. ex: manganese nodules, metal sulfides, and evaporites

grain size

the average size of the grains of material in a sample. also know as fragment or particle size. one of the most important components of lithogenous sediment

Calcite compensation depth (CCD)

the depth at which the amount of calcite (CaCO3) products 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 m

texture

the general physical appearances of an object

erosion

the group of natural process, including weathering, dissolution, abrasion, corrosion, and transportation, by which material is worn away from earth's surface

Opal

the hydrated form of silica

Lysocline

the level in the ocean at which calcium carbonate begins to dissolve, typically at a depth of about 4000 m (13,100 ft). Below the lysocline, calcium dissolves at an increasing rate with increasing depth until the calcite compensation depth (CCD) is reached

Productivity

the number of organisms present in the surface water above the ocean floor.

suspension settling

the process by which fine-grained material that is bing suspended in the water column slowly accumulates on the sea floor

paleoceangraphy

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

tests

the supporting skeleton or shall (usually microscopic) of many invertebrates