STRATIGRAPHY AND SEDIMENTATION (DEEP MARINE) Flashcards
Largest area of sediment accumulation on Earth
Deep Marine
How much of the area of the globe is occupied by ocean basins?
71%
Deeply incised steep sided erosional features that commonly cut continental slopes and which act as conduits for the transfer of water and sediment from the shelf and usually cnotrols the formation and position of submarine sea fans
Submarine Canyons
Flas surfaces interruptions over isolated hotspots which can be wholly submarine or may build up above water as volcanic islands
Seamounts/Guyot
Deepest part of the oceans formed in regions of subductions
Trenches
Mariana Trench is what kind of trench?
Starved
Remobilisition of mass of poorly sorted sediment rich mixture from the edge of the shelf or the top of the slope
Underwater Debri Flow
What characterizes the top surface of a submarine debris flow?
Grading up ito finer deposits due to dilution of the upper part
Dilute mixtures of sediment and water moving as mass flows under the influence of gravity and is the most important mechanism for moving coarse clastic materials in deep marine
Turbidity Currents
Deposits which can range from few mm to tens of meters ad are carried by flows with seds concetration of a few parts per thousands to 10%
Turbidites
Dilute: Turbidity Currents: Dense:
Density Currents
Low Density: Bouma Sequqnce = High Density turbidites:
Lowe Sequqnce
Low Efficiency system vs High Efficiency System
LES when sandy sediments are carried only short distance and tends to accumulate at the Basinal Margins with less mud
HES when sandy materia are hundreds of Kilometers tends to accumulate far from the basin margins and is muddy
An area near the basin margin where sediment is not deposited and there may be scouring of the underlying surface
Bypass Zone
Flow associated with triggering of Turbidity and Density currents
Quasisteady flow
A body of sediment on the sea florr deposited by mass flow prcesses that may be fan shaped but more elongate , lobate geometries are also common
submarine fan
Clastic: Submarine fans = Carbonate seds:
Slope-Apron System
Architectural elements/Components of a submarine fan system
1) Channels
2) Lobes
3) Sheets
These are components of a fan system where in sediment and water are funneld by scours that are not incised into bedrock but are rather into underlying submarine fan deposits
Submarine Channels
Deposits in submarine channels
Thick Sturctureless Coarse Sands to granule (Ta-b, S1-3)
Formed by the lateral spilling out of dilute portions of the flow which contains sand silt and mud and spreads out with a low angle, wedge shaped geometry
Submarine Channel Levee
deposits in submarine levee
Thiniing Tce Tde
Forms at the istal ends of channels where turbidity currents spra out
Depositional lobe
Depsitional characteristics of lobe progradation
Coarsening up
These contains most complete bouma sequence
Depositional Lobes (Ta-e or Tb-e)
Deposits of turbidity current that are not restricted to deposition on a lobe
Turbidite sheets
Four Submarine systems
1) Gravel dominated
2) Sandy
3) Mixed Sandy and Mus
4) Muddy
Parts and corresponsing architerctural elements*
Not applied for gravel and muddy systems
Upper Far(Inner fan) Channel and Levees
Mid Fan Deposiional lobes
Lower Fan Sheets
Source of Gravel domnated systems
Braided rivers or alluvial fas
Source of Sand rich systems which are less efficient and is chraracterized by high density (70% sand)
Shallow Marine
Source of Mixed sand and Mud which are high efficient (30-19% sand)
River/delta system
Largest sumarine fans systems are fed by with very elongate lobes and most of the sands are restricted to the channel
Large Rivers
Flute Marks: Flow Direction= _______________: Axis of Flow
Groove Marks
Which of the bourma sequence can be measured and use as a paleocurrent idicator?
Tc- Cross Laminated
Sucession on prograding fan sequence
Thin Turbidite Sheets
Coarsening Up Lobe deposits
Thin Sands levee deposits
Coarse Sand to Granule Channel deposits
depositional systems on cotinental slopes and adjacent parts of the basin floor that are not fed by discrete point source (Kumbaga sabog ang flow at hindi focused)
Slope Apron
Block of rocks in a debris avalance
Olistoliths
Reworked sand from the edge of the shelf
Spill-over sand
Deposits removbilized by Geostrophic or Thermohaline currents that flow along the sea floor parallel to the bathymetric contours of the continental margin
Contourites
Pelagic means
Open Ocean
Wind blown Suspened material that was loating in the ocean away from the shorelines and has settled on the sea floor
Pelagic sediments
organism that contribute to calcareous ooze
1) Forams
Nannoplanktons
2) Chrysophyte Algae
3) Coccoliths
Organism that form siliceous ooze
Diatoms 5-50microns
Radiolarians 5-500 microns
Lithification of Calcaerous ooze forms
Pelagic Mudstone
Lithification of Siliceous Ooze
Chert
Which is slower to form?
Silicerous ooze
Unstable Opal alters to
Chalcedont (Radiating)
Primary Chert: Deeep Sea = Secondary Chert:
Nodular in a host limestone
depths at which calcite starts to dissolve
Lysocline (3000m)
Depths at which calcite compeletelt dissolve
Caclcite Compensation Depth (4000m) not contsant
this marks the depth at which opaline silica dissolves because of pressure which is usually 6000 m
Opal Compensation Depth (OCD)
Red brown mudrocks are indicative of
Hadal zones
Fine grained sediment that is dervie from a nearby continent
Hemipelagic
Minerals that precipitate directly on the sea floor
Chemogenic ocean deposits
Silica that can be chemogenic
Zeolites
Black Smokers: Iron Sulfides = White smokes:
Barite and Calcium Silicates
Important fossil indicator of mudrocks formed at ocean basins
Graptolites
