OCE TEST 2
Card Set Information
OCE TEST 2
Lecture 4 - Marine Sediments
What are examples and properties of Lithogenous sediments
Eroded rock fragments from land
Reflect composition of rock from which derived
Most lithogenous sediments at continental margins
Coarser sediments closer to shore
Finer sediments farther from shore
Mainly mineral quartz (SiO2)
How are Neritic sediments distributed and in which regions are they normally found?
Shallow water deposits
Close to land
What are som Types of neritic lithogenous sediments
Mainly wave-depositedquartz-rich sands
Continental shelf deposits
from turbidity currrents
High latitude continental shelf
How are Pelagic sediments distributed and in which regions are they normally found?
Deeper water deposits
What are the most common sources of fine pelagic lithogenous sediments?
Volcanic ash (volcanic eruptions)
Fine-grained material transported by deep ocean currents
what are the main qualities of Abyssal clay (red clay) and how are they transported?
At least 70% of clay-sizedgrains from continents
Transported by winds andcurrents
Abundant if other sediments absent
What are examples of Biogenous marine sediments and of what two organisms are they mainly of?
Hard remains of once-livingorganisms
Shells, bones, teeth
Macroscopic (large remains)
Microscopic (small remains)
Tiny shells or tests settlethrough water column
Biogenic ooze (30% or moretests)
Mainly algae and protozoans
What are two examples of Silica in Biogenous sediments and what type of ooze do they produce?
(Produces Siliceous Ooze).
What are they main properties of Siliceous Ooze?
Seawater undersaturated with silica socontinually dissolves back into water
Siliceous ooze commonly associated with highbiologic productivity in surface ocean becauseonce buried, they don’t dissolve easily
Give examples of Calcium carbonate in biogenous sediments (2 organisms)
What properties describe Foraminifera(protozoans) and what type of ooze do they produce?
Use external food
What are some characteristics of Coccolithophores(algae)?
May use plates assunshades
What factors control the distribution of biogenous sediments?
Give examples of Carbonate deposits (2 examples)
Describe the properties Limestone.
White Cliffs of Dover, England ishardened coccolithophore ooze
What environment do Stromatolites experience and of what bacteria were they originated?
Warm, shallow ocean, high salinity
Calcareous ooze and the CCD? Describe warm water, shallow ocean and cool, deep oceans with respect to their saturation of calcium carbonate(s).
Warm, shallow ocean saturatedwith calcium carbonate
Cool, deep ocean undersaturatedwith calcium carbonate
depth at which asignificant amount of CaCO3 beginsto dissolve rapidly
Calcite compensation depth (CCD) At what 'cline?
Below lysocline, depth where CaCO3readily dissolves
little calcareous ooze
Rate of supply = rate at which the shellsdissolve
Minerals precipitate directly from seawater (Hydrogenous) Give examples (At least 4)
Small proportion of marine sediments
Distributed in diverse environments
Describe characteristics of Phosphates, it's use and describe the areas it would most likely to be found.
Phosphorus-bearing apatite sedimentary rock
Occur beneath areas in surface ocean of veryhigh biological productivity
phosphatesreleased into interstitial water by decomposition
Give examples of Carbonates (CaCO3) (At least 3)
Aragonite and calcite
Give examples of Cosmogenous marine sediments (At least 2)
Microscopic iron-nickel and silicate spherules
Give examples of Microscopic iron-nickel and silicate spherules (2 examples)
Usually mixture ofdifferent sediment types contain up to how much non-biogenic components?
biogenicoozes can contain up to 70% non-biogeniccomponents
Neritic sediments cover about _ of sea floor
Pelagic sediments cover about _ of sea floor
Distribution of neritic and pelagic marinesediments controlled by:
Proximity to sources of lithogenous sediments
Productivity of microscopic marine organisms
Depth of water
Sea floor features
How sea floor sediments represent surface ocean conditions
Microscopic tests sink slowlyfrom surface ocean to sea floor(10-50 years)
Tests could be movedhorizontally
Most biogenous tests clumptogether in fecal pellets
Marine sediments often representocean surface conditions preservesrecord of past
Abundance of marine life
Ocean current patterns
Major extinction events
Changes in climate
Movement of tectonic plates
How do researchers traditionally retrieve sediments?
Deep Sea Drilling Program
Ocean Drilling Program
Integrated Ocean Drilling Program
Studies reveal support for which theories about the ocean?:
drying of the Mediterranean Sea
global climate change