marine sediments Flashcards
divergence
spread apart
convergence
come together
what is sea floor spreading ?
Seafloor spreading is the continuous process of forming new igneous rock at midocean ridges by injection of magma that forms new seafloor
marine sediments
particles of various size from various sources and are deposited on the marine floor
what are the inputs of sediments to the ocean
Rivers (most)
Glaciers
Wind
Erosion
Volcanic debris
Ground water (least)
how are marine sediments produced ?
through chemical or physical weathering
What is physical weathering?
physical processes that cause rock fragmentation
what is chemical weathering
chemical reactions that alter rocks
what are the classifications of marine sediments
gravel (largest) , sand, silt and clay(smallest)
is mud a mixture of silt and clay?
yes
what what are the different marine sediment origins
Terrgienous, Biogenous, Authigenic(Hydrogenous), Cosmogenous
what indicates terrigenous origin ?
Eroded rock, volcanoes or airborne dust . basically anything created by terrain.
which sediment origins are internal and which are external ?
internal: terrestrial
external: biogenic or authigenic
terrigeneous material is typically is from
-rivers, 10^6 tons a year
-glaciers, they melt and their frozen debris settles on the ocean floor
-winds, aka aeolian dust
coastal erosion
-turbidities
what are the 3 major ocean basins
Pacific, Atlantic, Indian
what are turbidites?
rapidly accumulated terrestrial sediments like when earthquakes trigger avalanches
where can you find most terrigenous material
Dominantly neritic, pelagic in areas of low productivity
Examples: coarse beaches and shelf deposits
biogenous means
sediments from living things
biogenies material is typically made of ___
shells from planktonic organisms
the shells that make biogenies material are made from what ?
the shells are typically composed of either calcium carbonate or silica
Coccolithophores foraminifers and pteropods produce calcareous debris
where is biogenous material found ?
In regions of high productivity, dominantly pelagic , areas of upwelling, some beaches, shallow warm weather.
(basically areas where plankton can grow abundantly and die)
authigenic or hydrogenous material is from ___
chemical precipatation reaction in the sea water.
where can you find authigenic/hydrogenous material ?
Mid ocean ridges, areas starved of other sediment types, neritic and pelagic
what typically makes authigenic/hydrogenous sediment ?
Metal sulfides, manganese nodules, phosphates, some carbonates
Evaporites— salt deposits
cosmogenous material means
from space
where can you find cosmogenous material ?
Areas of significant deposit: Everywhere but in low concentration.
what is an example of cosmogenous material ?
meteorites and space dust
when referring to internal and external sediments, what do the term internal and external mean ?
internal means from the lan
external means from the sea
what is paleoceanography
study of Earth’s
oceanographic history involving the analysis of the ocean’s sedimentary record, the history of tectonic plate motions, glacial changes, and established relationships between present sedimentation
patterns and environmental factors.
what are the different types of core samples
piston, gravity, multicore
briefly explain the types of core samples
piston: pistol, shoot the ground
gravity: heavy weight pushes into the ground
multicore: same as gravity, but with multiple core samples
how are dredged rocks collected ?
collected by dragging an open steel box with an attached chain bag along the ocean bottom behind a ship.
Do biogenous sediments dissolve readily at shallow
depths on the continental shelf?
no
Do plankton species in coastal waters lack skeletons
no
Are planktonic organisms consumed by large
organisms, preventing deposition of skeletons?
no
rivers are 10 times more ____ than ____
terrigenous : biogenic
The large input of terrigenous
sediment to the continental margin
overwhelms the biogenous component
in the sediment. This explains what?
why biogenous oozes are rarely found near the shore
Why do red clays dominate far from
land in great water depths?
Minimal sediment input from land – Far from coasts, little sediment is delivered from rivers or erosion.
Slow sedimentation rates – Very little material accumulates in deep-sea environments, allowing fine red clays to settle.
Wind-blown dust – Fine particles from deserts are carried by wind over long distances and eventually settle in the deep ocean.
Low biological activity – In deep waters, there’s less biogenic material (like shells or skeletons), especially below the carbonate compensation depth (CCD), where calcium carbonate dissolves.
Iron oxides – Red clays get their color from iron oxide, which accumulates over time in the oxygenated deep ocean.
