Chapter 4 Oceanography
boulder, cobble, pebble, and granule are also known as what?
Gravel
Radiolarian ooze are
Heterotrophs ( all have symmetry )
What is a high amount of siliceous ooze associated with?
High productivity
what sediment is created from chemical reactions?
Hydrogenous Sediments
Lithogenous origin
derived from land
Biogenous origin
derived from organisms
Cosmogenous origin
derived from outer space
Where do hydrogenous sediments come from? What are some examples?
- Minerals precipitated directly from seawater - Ex: Iron manganese nodules, phosphates, evaporites, metal sulfides
Are cosmogenous sediments a large portion of marine sediments?
- No, they are overall insignificant
Hydrogenous origin
derived from water
Hydrogenous marine sediments
- Minerals precipitate directly from seawater * Maganese Nodules * phosphates * Metal Sulfides - small proportion of marine sediments
Properties of poorly-sorted sediments
- "immature sediment" - mixed sizes - turbidities
Properties of well-sorted sediments
- "mature" sediment - similar sizes - ex: beach sand - areas of high energy
In order to be called biogenic ooze it must contain
- 30% or more tests aka tiny shells
What is limestone made up of?
- CaCO3/ Calcite/ Calcium Carbonate
Carbonate deposits contain
- Carbonate (CO3) - Limestone (CaCO3) - Stromatolites
Why do we care about sediments?
- Determines past climates - Tracks movement of ocean floor - Tracks ocean circulation patterns - Determines nutrient availability - Pinpoints major extinctions
Resources from Marine Sediments
- Energy Resources: * Petroleum ( mainly from continental shelves) * Gas Hydrates - Sand and gravel ( Including tin, gold, etc) - Evaporative Salts - Phosphorite - Manganese nodules and crusts
Distribution of biogenous sediments
- Factors controlling distribution * productivity ( areas w/lots of life) * destruction (dissolving at depth ) * dilution ( ex: addition of lots of lithogeous sediments will lead to less biogenous sediments)
Calcium Carbonate is formed by and forms/makes what?
- Formed by Foraminifers and coccolithophores - forms calcareous ooze (which is chalk)
Biogenous Marine Sediments
- Hard parts of living things * Macroscopic ( ex: shells, bones, teeth, coral) * Microscopic (more common) ( ex: tiny shells or tests, settle through water column) - Biogenic ooze must contain 30% or more tests - Commonly either silica (SiO2) or calcium carbonate (CaCO3) - Silica-diatoms or radiolarians - Foraminifers and coccolithophores
Lithogenous Deposits based on size and energy
- High energy --> larger size particles - Low energy --> fine sized particles - Becomes finer with distance from shore
Iron-Maganese Nodules
- Lumps of manganese, iron, and other metals - Very slow growth rates-5mm/million years! - Still a mystery!
What is the primary component of cosmogenic sediment?
- Meteorites
Neritic
- Shallow water deposits * mostly lithogenous (quartz) * beach * Turbidite (from turbidity currents) * glacial deposits
What are stromatolites?
- a calcareous mound of lime-secreting cyanobacteria and sediment - found in Warm, shallow-ocean waters with high salinity - Cyanobacteria trap sediment in mucous mats
what is weathering?
- a process by which rocks are BROKEN DOWN by chemical and mechanical means
Why do you not often find calcareous ooze below the CCD?
- bc it easily dissolves below the CCD therefore there is no sediment accumulation to form ooze
Siliceous ooze is found where?
- below the CCD - in areas of high biologic activity - cold, deep areas
Size Classification of sediment grains from biggest to smallest particles
- boulder - cobble - pebble - granule - sand - silt - clay
What things do Biogenic and Lithogenic sediments have in common
- can be used to determine past climates - used to support the theory of seafloor spreading - used to track ocean circulation patterns
Below the CCD....
- carbonate readily dissolves - no calcareous sediment accumulation - scarce calcareous ooze below 5000 meters in modern ocean - ancient calcareous ooze at greater depths if moved by sea floor spreading
Phosphates
- coatings on rocks on continental shelf - fertilizer
Halite is
- common table salt
Siliceous Ooze
- commonly associated with high biologic productivity in surface ocean - areas with high productivity and many silica tests sinking leads to silica tests accumulating as siliceous ooze - areas with few silica tests sinking and lower productivity leads to the silica tests dissolving
Metal Sulfides
- contain iron, nickel, copper, zinc, silver, and other metals - hydrothermal vents
Pelagic
- deep ocean deposits * finer, grained sediments, slowly deposited * mostly biogenic * abyssal clay: red clays (high iron)
Lysocline :
- depth at which a significant amount of CaCO3 begins to dissolve rapidly
Carbonate Compensation Depth (CCD):
- depth where CaCO3 readily dissolves (5000 meters)
What primary organisms make up biogenous sediments?
- diatoms - radiolarians - coccolithophores - foraminifers
What organisms are made of silica?
- diatoms - radiolarians
How/Why does ooze form?
- due to oversaturation
What organisms are made of calcium carbonate?
- foraminifers - coccolithophers
Evaporites
- form when seawater evaporates - Halite (common table salt) and gypsum
Cosmogenous Marine Sediments
- formed from meteorites - overall, insignificant proportion of marine sediments
What size particles would be deposited in high energy environments? Low energy?
- high energy: larger sized particles - low energy: fine sized particles
A high siliceous ooze amount is associated with what?
- high productivity
Where do silica, diatoms, and radiolarians dissolve?
- in places where sea water under-saturated with SiO2 ( Silica)
What are four examples of hydrogenic sediments?
- iron maganese nodules - metal sulfides - phosphates - evaporites
What do radiolarians look like?
- known as "snowflakes of the sea" - they are symmetrical
Calcareous Sediment accumulation leads to what?
- leads to calcareous ooze
what do foraminifers look like?
- look like shells - have segmented or chamber tests
What do diatoms look like?
- looks like a "greenhouse" - 2 sides of silica to allow light in for photosynthesis - hole for nutrients
Biogenic Sediments ( Venn Diagram List)
- made up of shells, bones, teeth, and coral - chalk - pelagic (offshore) deposits - contains diatoms, radiolarians, foraminifers, and coccolithophores - comes from living things - most abundant materials are calcium carbonate (CaCO3) or Silica (SiO2)
what do coccolithophores look like?
- makes chalk - 10-100 times smaller than a diatom - spherical/round tests
What is the primary component of hydrogenic sediment?
- metal sulfides - iro manganese nodules - evaporites - phosphates - small proportion of marine sediments
Lithogenous Composition
- most abundant MINERAL is quartz ( SiO2) ( in a majority of sediments) - deposits based on size and energy * high energy --> larger size particles * low energy --> fine sized particles * becomes finer with distance from shore
continental shelf has what kind of sediments?
- neritic sediments - lithogenous sediments
Lithogenic Sediments ( Venn Diagram List)
- originated from rocks - particles are transported by wind, water, glaciers, or turbidity (erosion) - particles are broken down by physical and chemical weathering (weathering) - Quartz (SiO2) is the most abundant material - neritic (nearshore deposits) - classified by size and roundness(gravel, sand, silt , clay)
What is the relationship between particle size and distance from the shore?
- particles become finer/smaller with distance from the shore
Factors controlling biogenous sediment distribution
- productivity ( areas w/lots of life) - destruction (dissolving at depth ) - dilution ( ex: addition of lots of lithogeous sediments will lead to less biogenous sediments)
What is the primary component of biogenous sediment?
- silica - calcium carbonate
What is ooze?
- soft mud on the ocean floor composed of organisms
which ocean is one of the most productive oceans of the world?
- the arctic ocean ( especially at the ice edge)
Where do calcium carbonate, foraminifers, and coccolithophers dissolve?
- they easily dissolve below the CCD ( Carbonate Compensation Depth)
Poorly sorted sediments have what kind of energy?
- they have low energy
precipitate
- to cause a substance to be deposited in solid form from a solution.
Calcareous Ooze and the CCD
- warm, shallow ocean areas are saturated with calcium carbonate - cool, deep ocean areas are undersaturated with calcium carbonate (siliceous ooze) * acidity increases with depth * lysocline : depth at which a significant amount of CaCO3 begins to dissolve rapidly * Carbonate Compensation Depth (CCD): depth where CaCO3 readily dissolves ( 5000 meters)
Lithogenous sediments
- weathered and eroded rock - has properties of original rock
What is the difference between weathering and erosion?
- weathering: a process by which rocks are BROKEN DOWN by chemical and mechanical means - erosion: The process by which wind, water, ice, or gravity transports/MOVES soil and sediment from one location to another
Does ooze form when the water is saturated or unsaturated with the primary component?
- when the water is saturated with the primary component
How are lithogenous sediments transported from land?
- wind, water, glaciers ( mostly to continental margin) - gravity ( turbidity currents) (erosion)
Can calcareous ooze be found below the CCD? Explain.
- yes, but in very scare amounts - as well as ancient calcareous ooze that was moved by sea floor spreading ( under abyssal clay or siliceous ooze)
Calcareous ooze is found where?
-above CCD -near/on top of mid ocean ridge - warm, shallow areas
siliceous ooze and calcareous ooze are both what?
BIOGENIC
What is the primary component of lithogenous sediment?
Quartz
what is erosion?
The process by which wind, water, ice, or gravity transports/MOVES soil and sediment from one location to another
example of coccolithophores
algae
example of diatoms
algae
most sediments are or are not a mixture of lithogenous, biogenous, hydrogenous, and cosmogenous sediments
are
Diatomaceous Ooze (Silica Diatoms ) are
autotrophs
coccolithophores are heterotrophs or autotrophs?
autotrophs
diatoms are heterotrophs or autotrophs?
autotrophs
Finest grain material in sediment is
clay
siliceous ooze is found near what temperature of water?
cold water
Sorting Indicates
energy of transport and duration of deposition
foraminifers are heterotrophs or autotrophs?
heterotrophs
radiolarians are heterotrophs or autotrophs?
heterotrophs
Size and shape descriptions of sediments usually affect what type of sediments?
lithogenous sediments
Lithogenous is neritic or pelagic?
neritic
is there just biogenic ooze?
no
Biogenous is neritic or pelagic?
pelagic
example of foraminifers
protozans
example of radiolarians
protozoans
what is the most common mineral and is also very hard
quartz
calcareous ooze is found near water temperature of water?
warm water