Marine Sediments Flashcards
why marine sediments are interesting to oceanographers.
Reveals Earth’s history.
Provides clues to past geographic distributions of marine organisms, movements of the ocean floor, ocean circulation patterns climate changes on Earth and global extinction.
four primary types of marine sediment
Lithogenous
Biogenous
Hydrogenous
Cosmogenous
List the past conditions that scientists can infer by analyzing marine sediments.
Sea surface Temperature Nutrient supply abundance of marine life atmospheric winds ocean current patterns volcanic eruptions major extinction events changes in Earth’s climate movement of tectonic plates
paleoceanography
The study of how the ocean, atmosphere, and land have interacted to produce changes in ocean chemistry, circulation, biology and climate.
lithogenous sediment
Derived from pre-existing rock material that originates on the continents of islands from erosion, volcanic eruptions, or blown dust. Also referred to as terrigenous sediment.
Characteristics of Lithogenous Sediment
dsaf
List the transportation mechanism that carry sediment to the ocean
Streams, wind, glaciers, and gravity.
List the submarine transportation mechanisms that carry sediment beyond the continental margin
Turbidity currents
In which marine region do the largest marine sedimentary deposits form
Around the margins of the continents.
why most lithogenous particles, including most sand (but not Hawai’i sand), are quartz
Quartz is a major component of most rocks and since it is resistant to abrasion it can be transported long distances.
the primary sediment transportation mechanism from the Sahara Desert to the ocean.
Prevailing winds
list the primary sediment sizes from coarse-grained to fine-grained.
Boulder, cobble, pebble, granule, sand, silt, clay
why lithogenous sediments tend to become finer with increasing distance from shore.
Because high-energy transporting media predominate close to shore and lower-energy conditions exist in the deep-ocean basins.
Define well-sorted sediment and poorly-sorted sediment.
Well-sorted sediment is sediment composed of particle that are primarily the same size whereas poorly-sorted sediment is sediment that is comprised of a variety of differently sized particles.
Define neritic deposits and pelagic deposits.
Neritic deposits are found on continental shelves and in shallow water near islands and are generally coarse grained; pelagic deposits are found in deep-ocean basins and are typically fine grained
Decribe the characteristics and formaton of glacial deposits.
Poorly-sorted deposits containing particles ranging from boulders to clays may be found in the high-latitude portions of the continental shelf.
Describe the characteristics and formation of abyssal clays.
70% (by weight) fine, clay sized-particles, composed of particles transported great distances and deposited on the deep ocean floor, and are red-brown due to the oxidized iron it contains.
biogenous sediment
The remains of hard parts of once-living organisms.
Explain why most marine biogenous deposits are called oozes
Because marine biogenous deposits resemble fine-grained, mushy material, or ooze.
List the two primary biogenous sediment compositions: name and chemical formula.
Calcium carbonate (CaCO3) and Silica (SiO2)
List two microscopic, planktonic organisms with siliceous tests.
Diatoms and radiolarians
List two microscopic, planktonic organisms with calcareous tests.
Foraminifers and coccolithophores
Explain why diatoms and coccolithophores live near the ocean’s surface.
They need sunlight because they photosynthesize
List the three factors that control the formation of biogenous oozes.
Production, destruction, and dilution
Explain why biogenous deposits dominate the pelagic sea floor.
Because there is so little lithogenous sediment deposited at great distances from the continents that could dilute the biogenous material.
List the three dominate siliceous oozes types.
Diatomaceous ooze, radiolarian ooze, and silicoflagellate ooze
List the two dominate calcarous ooze types.
coccolith ooze, foraminifer ooze
Explain why calcareous oozes are rarely form on the deep-sea floor.
The carbonic acid dissolves calcareous material by the cold waters CO2
Define the calcite compensation depth (CCD)
The depth at which the amount of calcite 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
Give the average CCD depth
4500 m
Explain the relationship between upwelling and siliceous deposits.
siliceous deposits form below cool surface water regions and upwellings being deep, cld nutrient rich water to the surface.
Define hydrogenous sediment
sediment that forms from precipitation from ocean water or ion exchange between sediment and ocean water
Describe growth of a Mn nodules
requires extremely low rates of lithogenous nodules or biogenous input so that the nodes are not buried
Give the average Mn nodule growth rate.
5mm per million of years
