Marine Provinces and Marine Sediments Flashcards
Represent earth’s largest museum with displays of earth history, dating millions of years. It provides clues to history, specifically on:
- Marine Organism Distribution
- Ocean Floor Movements
- Ocean Circulation Patterns
- Climate Change
- Global Extinction Events
Marine Sediments
Destroyed >75% of species on earth (dinosaurs, many others). After extinction, many groups underwent sudden and prolific divergence into new forms and species (ex mammals diversified into horses, whales, bats, primates). Boundary clay showed high levels of metal _____? which is rare in earth’s crust
K-Pg Extinction Event, Iridium
Size and Shape of Particles. Its origins can be:
- Worn rocks
- Living Organisms
- Minerals dissolved in water
- Outer space
Texture
Over time, sediments can become _____ and form what?
Lithified, Sedimentary rock
More than half of rocks exposed on the continents are sedimentary rocks deposited in ancient ocean environments and uplifted onto land by ____?
Plate Tectonics
Mt. Everest (in Himalaya Mountains) consists of ____, which originated in sea floor deposits
Limestone
The study of the history of the oceans in the geologic past. It is the study of how ocean, atmosphere, and land interactions have produced changes in ocean chemistry, circulation, biology, and climate.
Paleoceanography
As sediments accumulate, they preserve materials and conditions of the environment that existed in the overlying water column; can infer sea surface temp, nutrient supply, abundance of marine life, atmospheric winds, ocean current patterns, volcanic eruptions, major extinctions events, changes in climate, movement of tectonic plates
Sediment Cores
Unconsolidated organic and inorganic particles that accumulate on the ocean floor
Sediment
Sediment Load:
- Dissolved chemicals, ions
- Fine-grained particles, carried in water column
- Coarse-grained particles, remain on or near stream bed by rolling, sliding, or jumping
- Dissolved Load
- Suspended Load
- Bed Load
Sediments are classified according to its:
- ?
- ?
- Size
- Origin
Sediments are classified by size according to the ____?. It’s measured on a _____ scale called the “___”, which classified particles by size from “clay” to “boulder”.
Wentworth Scale, Log Base 2 Scale, Phi Scale
This indicates the energy of the transporting medium.
- more energy needed
- low energy environments
Particle Size
- Larger Grain Size
- Small Particles
Same size, found in area where energy change within narrow limits (ex. deep ocean sediment)
Well-sorted
Multiple sizes, found where energy fluctuates over wide range (ex. rubble at base of cliff, sediments carried by turbidity currents)
Poorly-sorted
The function of energy of the environment – exposure of area to action of waves, tides, currents. Well sorted sediments occur in env where energy fluctuates within narrow limits (ex deep ocean sediments). ____? form in env where energy fluctuates over wide spectrum (ex. rubble at base of cliff, sediments carried by turbidity currents)
Sorting, poorly sorted sediments
Indicated by several factors
- decreased silt and clay content
- increased sorting
- increased rounding of grains, as a result of weathering and abrasion
Sediment Maturity
The _____ the time and distance of transportation, the ____ the rounding and the degree of sorting
Longer, Better
Graphs the relationship between particle size and energy for erosion, transportation and deposition. ____ means pick up and move.
Hjulstrom’s Diagram, Erode
Sediments Originate from Numerous Sources:
1. Terrigenous
2. Terrigenous
3. Biogenic
4. Autogenic
5. Cosmogenic
- Weathering and erosion of the continents
- Volcanic eruptions
- Biological activity
- Chemical processes within the oceanic crust and seawater
- Impacts of extra-terrestrial objects
also called Lithogenous sediments
Terrigenous Sediments
- Eroded rock fragments from land
- Also called terrigenous
- Reflect composition of rock from which derived
- Produced by _____, the breaking of rocks into smaller pieces.
Lithogenous Sediments, Weathering
Most abundant, derived from weathering of rocks at or above sea level (e.g., continents, islands)
- from erosion, volcanic eruptions,
blown dust
- two distinct chemical compositions
ferromagnesian, or iron-magnesium bearing minerals
- non-ferromagnesian minerals – e.g., quartz, feldspar, micas
- largest deposits on continental margins (less than 40% reach abyssal plains)
transported by water, wind, gravity, and ice
- ____? – most familiar continental igneous rock , source of quartz and clay (2 of the most common component of terrigenous sediments)
- ____ are main source of terrigenous sediments. Lithogenous (lithos = stone) derived from preexisting rock material
Lithogenous/Terrigenous Sediments, Granite, Rivers
One of the most abundant, chemically stable, and durable minerals in earth’s crust is _____?, composed of silicon and oxygen in the form of SiO2 – same composition as ordinary glass. Because ____ is resistant to abrasion, it can be transported long distances and deposited far from the source area. Majority of lithogenous deposits such as beach sands are composed primarily of _____.
Quartz
Primary dust source is ____ in Asia and North Africa
Deserts
Dust from ____? is carried downwind across the _____?, hence ships traveling downwind are dusty. Some dust fall in ____? where it has been linked to stress and disease among corals.
Sahara Desert, Atlantic, Caribbean
Slow moving mass of ice formed by accumulation of snow on mountains or near poles. Boulder to clay size particles also eroded and transported to oceans via glacial ice
Glaciers
A large floating mass of ice detached from a glacier or ice sheet and carried out to sea.
Iceberg
Cloudiness or haziness of water. Sediment also transported to the open-ocean by gravity-driven ____ currents.
Dense ‘slurries’ of suspended sediment moved as ______ underflows
- Means for deep water ventilation of the Sulu Sea
Turbidity / Turbidity Currents
Cut some of TransAtlantic telegraph cable south of Newfoundland. Cables close to earthquake broke simultaneously with earthquake, but cables that crossed the slope and deeper ocean floor at greater distances from the earthquake were broken progressively later.
1929 Grand Banks Earthquake
Typically consists of rock fragments and silicate materials. _____ means formed by rock breakdown. _____ means volcanic rock.
Rock-clastic sediments, Clastic, Pumice
Begins as the hard parts (shells, bones, teeth) of living organisms ranging from minute algae and protozoans to fish and whales. What are the two most common chemical compounds in biogenous sediments?
Biogenous Sediments, Calcite, Silica
Biogenous sediments classified into:
- Large enough to be seen without microscope; ex. shells, bones, teeth
- Accumulate in deep-ocean floor; ex. tiny shells called tests
- Macroscopic
- Microscopic
_____ are 10-100x smaller than most diatoms, hence they are called _____
Cocolithophores, Nanoplanktons
Calcareous or siliceous ‘oozes’ if biogenic component greater than ____. Median grain size typically less than _____ (i.e., silt or clay size particles)
30%, 0.005mm
_____ (primarily diatom oozes) cover __%? of the ocean floor
Siliceous Oozes, 15%
Tests are perforated with small holes in intricate patterns to allow nutrients to pass in and waste products to pass out. Two parts of the _____’s test fit together
Diatom
Have long spikes or rays of silica protruding from their siliceous shells, they display well-developed symmetry hence they are described as the living snowflakes of the sea. _____ oozes are more commonly found in the ____? regions.
Radiolarians, Equatorial
____? (foraminifera, coccolithophores) cover ____? of the ocean floor. Distribution controlled largely by _____? processes
Calcareous Oozes, 50%, Dissolution
Affected by temperature, pressure, CO2
solubility of CaCO3 increases in colder water and at greater pressures
Dissolution
Photosynthetic Algae, _____ are individual plates from dead organism. _____ are lithified coccolith-rich ones.
Coccolithophores, Coccoliths, Rock Chalk
- Depth where dissolution begins
- Depth where calcium carbonate has dissolved
- Lysocline
- Carbonate Compensation Depth or CCD
- Calcareous hard parts of invertebrates
- Thanatocoenosis
- Ease of identification depends on _____
Carbonate Sand Grains, Degree of Damage
_____ is a genus of green macroalgae. The algal body (thallus) is composed of calcified green segments. _____ is deposited in its tissues, making it inedible to most herbivores.
Halimeda, Calcium Carbonate
- Coral Fragments
- Coral reef-associated algae such as Halimeda, Mollusks, some Echinoderms and Foraminifera
Coral Reef-Derived Beach Sediments
Minerals ____? daily from seawater.
- Manganese Nodules
- Phosphates
- Carbonates
- Metal Sulfides
Small proportion of marine sediments and is distributed in diverse environments.
Hydrogenous Marine Sediments
- Produced by chemical processes in seawater (due to change in temperature, pressure or addition of chemically active fluids
- Essentially solid chemical precipitates of several common forms
Hydrogenous (or Authigenic) Sediments
Form in surface waters supersaturated with calcium carbonate (ex. short aragonite crystals and oolites)
Non-biogenous Carbonates
- Phosphate crusts (containing greater than 30% P2O5) occurring as nodules
- Formed as large quantities of organic phosphorus settle to the ocean floor
- Unoxidized material is transformed to phosphorite deposits
- Found on continental shelf and upper slope in regions of high productivity
Phosphorites
Occur abundantly as coatings on rocks and as nodules on the continental shelf and on banks at depth shallower than 1000m. Conc of _____ in such deposits commonly reach 30% by weight and indicate abundant biological activity in surface water where they accumulate.
Phosphates
- Surficial deposits of manganese, iron, copper, cobalt, and nickel
- Accumulate only in areas of low sedimentation rate (e.g., the Pacific)
- Develop extremely slowly (1 to 10 mm/million years)
Manganese Nodules
____ object may be a piece of lithogenous sediment, coral, volcanic rock, fish bone, shark’s tooth
Nucleation
_____ contain:
- Important for making high-strength steel alloys
- Used in electrical wiring, in pipes, and to make brass and bronze
- Used to make stainless steel
- Used as an alloy with iron to make strong magnets and steel tools
Nodules,
- Manganese
- Copper
- Nickel
- Cobalt
- Form where there is restricted open ocean circulation and where evaporation rates are high (ex Mediterranean Sea).
- Composed dominantly of varying proportions of halite (rock salt) (NaCl), anhydrite (CaSO4) and gypsum (CaSO4-2H2O.
- May be classified as chlorides, sulfates or carbonates on the basis of their chemical composition
Evaporites
Surrounded by land except for shallow connection to Atlantic Ocean through the Strait of Gibraltar which is 14 km wide. 6million years ago, drop in sea level cut off Atlantic Ocean. Arid climate resulted in high evaporation rates. Dissolved substances began to precipitate. Salt deposits are 4000m thick. Half million years later, erosion or rise in sea level caused dam at Gibraltar to be breached and Med started to refill.
Mediterranean Sea
- Sediments derived from extraterrestrial materials
- Includes micrometeorites and tektites
Cosmogenous Sediments
- Debris from meteors that settle around impact site, composed of silicate rock or iron and nickel.
- A small body of matter from outer space that enters the earth’s atmosphere, becoming incandescent as a result of friction and appearing as a streak of light.
Meteorites
- Result from extraterrestrial impact events on earth or other planets that eject small molten pieces of crust
- Fragments of earth’s crust melt and spray outward from impact crater
crustal material re-melts as it falls back through the atmosphere - Forms ‘glassy’ ___
Tektites
In Marine Sediment Collection, early explorations used _____, while modern explorations used:
- Hollow steel tubes collect sediment columns
- Collects deep ocean sediment cores
Dredges
- Cores
- Rotary Drilling
Net or wire baskets dragged across the bottom to collect loose bulk material, surface rocks, and shells
Bottom Dredge
Hinged devices that are spring- or weight-loaded to snap shut when sampler strikes the bottom
Grab Sampler
Hollow pipe with sharp cutting end. ______ is forced down into the seafloor by its weight or for longer cores, by a piston device within the core barrel that uses water pressure to help drive the corer into the sediments. Sediments obtained has undisturbed sediment layers
Piston Corer, Free-falling Pipe
- Drive a rectangular metal box into the sediment, with doors that close over the bottom of the box before sample is retrieved.
- Used when large and undisturbed surface sediment needed
Box Corer
- Measure carbon flux
- Estimates Global carbon cycle
- Important for study of Climate change
Sediment Traps
- Originally believed deepest parts of the the ocean were in the _____?
- Estimates of depths (soundings) go back centuries, but details of seafloor didn’t arise until the late 19th century with the laying of transatlantic telegraph lines
Seafloor Investigation, Middle
- (bathos = depth, metry = measurement)
- Ocean depths and topography of ocean floor (topo = place, graphy = description)
Bathymetry
- Rope/wire with heavy weight
- Known length
Sounding
1st recorded attempt to measure ocean’s depth conducted in the Mediterranean Sea in 85BC by Greek named ____?
Posidonius
- Comprehensive scientific expedition
- Ship refitted with laboratories, winches, and sounding scope
- 3.5 yr voyage; every so often ______ crew stopped and measured the depth and other ocean properties. Found out the deep ocean floor not flat but with had significant relief (variations in elevation)
HMS Challenger
- Reflection of sound signals (pings)
- 1925 German ship Meteor
- Invented in 1920
- invented in early 1900s. In 1925, Meteor used _____to identify underwater mountain range
Echo Sounder
Depth Formula:
What is V (Speed of Sound?):
Depth = V * (T/2)
V = 1507 m/s
- 1950s
- Focused High-Frequency Sound Beam (Resolution of 1m)
- First reliable sea floor maps produced using _____
- Helped confirm sea floor spreading and plate tectonics
Precision Depth Recorder (PDR)
Multiple simultaneous sound frequencies
Multibeam Echo Sounders
- The first multibeam echosounder, made it possible for a survey ship to map the features of the seafloor along a strip up to 60 km wide.
- Hull mounted _______emit multiple beams of sound waves, which are reflected off the ocean floor.
- From data, can determine the depth, shape, and whether bottom is rock, sand or mud. Can produce detailed image of sea floor bathymetry
Seabeam, Multibeam Instruments
SONAR, makes picture with sound
Sounding Navigation and Ranging
Can be towed behind ship to provide very detailed bathymetric strip map. In deep water where detailed survey is required, _____ can provide enhanced views of the seafloor.
(ex: _____ and _____)
Side-scan Sonar
- GLORIA (Geological Long Range Inclined Acoustical Instrument)
- Sea MARC (Sea Mapping and Remote Characterization)
- Gets close to seafloor so it can image with higher resolution
- Trade off is slower, more limited coverage
Deep-Tow Sonar
- Uses Satellite Measurements
- Measures sea floor features based on gravitation bulges in sea surface
- Indirectly reveals bathymetry
- The result is that the ____ roughly
reflects the ______
Sea Floor Mapping From Space, Surface, Bottom Topography
- Air Guns
- Strong, low frequency sounds
- Details ocean structure beneath sea floors
Seismic Reflection Profiles
Good for determining subsurface properties; application in mineral and petroleum exploration
Seismic Profiling
3 Major Ocean Provinces
- Shallow-water areas close to shore
- Deep-water areas farther from land
- Submarine mountain range
- Continental Margins
- Deep-ocean Basins
- Mid-Ocean Ridge
- Includes: Shelf, Slope and Rise
- Make up ____%? of ocean floor
Continental Margins, ~21%
2 major types of Continental Margins:
- Relatively little earthquakes/volcanic activities ; facing the edges of diverging plates
- Much movement; near the edges of converging plates or where plates are slipping past each other; coincide with plate boundaries
- Passive (e.g. Atlantic)
- Active (e.g. Pacific)
Shallow submerged extension of a continent; more similar to the continent than the deep-ocean floor; varying widths depending on proximity to plate boundary (active or passive margin) and currents and sea level
Continental Shelf
Transition between gently descending continental shelf and deep ocean floor; formed of sediments that reach the edge of shelf and transported over the side; at shelf break (~ 140 m)
Continental Slope
Due to underwater “avalanche” triggered by e.g., earthquakes
Submarine Canyons
Along passive margins; base of slope covered by an apron of accumulated sediment (100-1000km width)
Continental Rise
- Make up ______ of Earth’s surface
- Includes
- Abyssal plains and hills
- Volcanic peaks
- Trenches
Ocean Basins, More than Half
Majority of ocean trenches are along the margins of the _____, where plates are being subducted. Most of the world’s large earthquakes and active volcanoes occur around the _____.
Pacific Ocean, Pacific Rim / Pacific Ring of Fire
- Very flat depositional surfaces starting from base of continental rise
- 4500 – 6000 meters deep
- Next to trenches they are the deepest parts of the ocean
- Suspension settling of very fine particles
- Sediments cover ocean crust irregularities so it looks flat…like snow
- Well-developed in Atlantic and Indian oceans
Abyssal Plains
- Poke through sediment cover
- Below sea level:
- _____ are less than 1 km
- _____, _____, ______ at least 1 km above seafloor
Above sea level: - _____
Volcanic Peaks
Below Sea Level:
- Abyssal Hills <1 km
- Seamounts, Tablemounts, Guyots >= 1km above seafloor
Above Sea Level:
- Volcanic Islands
Volcanoes that don’t rise above sea surface;
Seamounts
If they rose above sea level in the past and eroded to a flat top by waves
Guyots
Broad undersea mountain chains; Location of diverging plates;
- Oceanic ridge
- Oceanic rise
Features;
- Central rift valley, faults and fissures
- Pillow basalts
- Hydrothermal vents
Mid-Oceanic Ridges
Volcanic igneous rock that forms when lava of basaltic composition is erupted underwater, rapidly cooled w/ seawater
Pillow Basalts
Solar Energy = Photosynthesis
Hydrothermal Energy = _____?
Instead of Oxygen, hydrothermal energy uses ____?
Chemosynthesis, Sulphuric Acid
- _____ is a 13-million-hectare underwater plateau located near Aurora. It is larger than Luzon and is consideredpart of the Philippines’ continental shelf.
- It is potentially a rich source of natural gas and other resources such as heavy metals. It is about 2,000 to 5,000 meters deep.
- In 2012, the United Nations Commission on the Limits of the Contintental Shelf (UNCLOS) confirmed _____ as part of the Philippines’ continental shelf. Under the UN Convention on the Law of the Sea (UNCLOS), the continental shelf comprises the seabed and subsoil of the submarine areas 200 nautical miles (NM), or 370 kilometers, from a state’s baselines or “edges.”
- According to scientific data based on seismic, magnetic, other geological features, the Benham Rise region is an extension of the Philippines’ continental shelf.
Benham Rise
