Sediment Flashcards
What is sediment?
Particles of organic and inorganic matter that accumulate
in loose, unconsolidated form
What do the different colors of sediment indicate about their origin?
White: biological origin
-Gray: crustal (silica)
-Red (brown): oxidation (aerobic conditions need O2 to turn metal to rust)
-Black or blue: anoxic conditions
What is terrigenous sediment?
Comes from land, most abundant type
What is biogenous sediment?
Siliceous and calcareous compounds derived from
living organisms
Plants and animals extract dissolved silica and
calcium carbonate from water to produce shells and
skeletons
How can you use biogenous sediment to know what ocean conditions were?
Look at the abundance of different species and you will know what the conditions were based on that organism’s preferences (salinity, temp, etc)
Most abundant where there were nutrients available
What is hydrogenous sediment?
Precipitate directly from seawater
Source of dissolved minerals
Submerged rock and sediment, hydrothermal vents,
oceanic ridges, etc…
were formed where they are found
What is cosmogenous sediment?
Extraterrestrial in origin
impacts by larger asteroids and comets
Why does sediment type vary by depth?
There isn’t enough energy to transport bigger materials so the deeper in the ocean, the finer the particle of sediment
Why is calcarious ooze so well known and what is it made of?
White cliffs of dover– pure white sediment out of the ocean to form “marine snow” in areas with high CO2 in the water
Made from calcium carbonate
What is silicious ooze made from?
formed from radiolarians and diatoms
Why is the ocean floor reflective of conditions when thinking about ooze?
Organisms that lived there are eaten by other things and preserved in feces which sink much faster
What are hydrogenous deposits?
most originate from chemical reactions that occur on existing particles, form around things on the ocean floor
oolites, evaporites, manganese nodules
sedimentary rock
What are oolites?
decrease in acidity or increase in temperature can
cause calcium carbonate to precipitate from water
in shallow seas with high biological productivity,
microorganisms use CO2 during photosynthesis, water
slightly less acidic, shallow water warms, calcium
carbonate precipitates around nuclei forming small smooth stones
What are evoporites?
precipitate out of solution when water evaporates
salt lakes
What are manganese nodules?
form around nuclei (anything, sharks teeth, crystals
animal skeletons, etc…)
