Marine Sediments Marine Sediments Origin, Composition, and DistributionOrigin, Composition, and Distribution
Introductory OceanographyIntroductory OceanographyRay Rector - Instructor
Example of Seafloor SedimentsExample of Seafloor SedimentsExample of Seafloor SedimentsExample of Seafloor Sediments
Shallow Underwater Carbonate Sand Dunes - Bahamas
Ocean Basins are Vast Sinks for SedimentOcean Basins are Vast Sinks for Sediment
Land- and plankton-derived sediments settle on both the continental margins and on the deep ocean seafloor
Two Major Types of Marine Sediment Two Major Types of Marine Sediment
Depositional Environments Depositional Environments Shallow Margin = Littoral and Neritic
Deep Sea = Pelagic
NeriticPelagic
Littoral
Seafloor Sediment ProvincesSeafloor Sediment Provinces
Continental shoreline = Littoral Province
Continental shelf = Neritic Province
Continental slope to rise = Transitional
All deep sea regions = Oceanic or Pelagic
Cross-Section Profile of an Ocean BasinCross-Section Profile of an Ocean Basin
Four Compositional Types Four Compositional Types of Seafloor Sedimentsof Seafloor Sediments
1. TerrigenousTerrigenous
Sources: Erosion of land; volcanic eruptions; wind-blown dust
Material: Gravels, Sands, Silts, and Clays
2. BiogenousBiogenous
Sources: Organic; accumulation of plant and animal hard parts
Material: Calcareous and Siliceous Oozes
3. HydrogenousHydrogenous
Sources: Precipitation of minerals from solution
Material: Carbonates, Metal Oxides and Sulfides
4. CosmogenousCosmogenous
Sources: Extraterrestrial dust and meteorites
Material: Tektite particles, Glassy spheres, Silicate dust
Type and Locality of Marine SedimentsType and Locality of Marine Sediments
Marine Sediment Sampling MethodsMarine Sediment Sampling Methods
Piston Coring
Bucket-Scooping
Submersible
Drilling
Marine Sediment Sampling LocationsMarine Sediment Sampling Locations
Terrigenous Sediments Sources: Erosion of land; volcanic eruptions; wind-blown dust; icebergs
Material Comp: Quartz, Feldspar, Mica, Amphibole, Fe Oxide, & Clays Material Size: Cobbles, Gravels, Sands, Silts, and Clays
Sediment from rivers
Ash from volcanic eruptions
Wind-blown material Sediment-filled glacial ice flows
Biogenous Sediments Sources: Carbonate reefs; Benthic shelled-animals; Plankton
Material Comp: Calcium carbonate and Silica
Material Size: Gravel, Sand, Silt, and Clay
Coral and Sponge Reefs
Microscopic PlanktonBenthic shelled-animals
Type and Locality of Marine SedimentsType and Locality of Marine Sediments
Continental Margins of the WorldContinental Margins of the World
Seafloor that includes shoreline, continental shelf and slope
Submerged continental margins are shown in pale orange color
Continental Margin SettingsContinental Margin Settings
Seafloor that includes shoreline, continental shelf and slope
Key Points
1) Shallow marine sediments that deposit along shorelines and offshore shelf are termed littoral and neritic
2) Coast and shelf sediments are of two types:
Land-derived inorganic rock and mineral fragments of gravel, sand, silt, and clay
Organic carbonate and silica materials of marine life skeletons from reefs and sea bottom habitats
Carbonate, silica and phosphate seawater precipitates
3) Shelf sediments mostly arrive via rivers
4) Coastal sediments may reach deep waters via turbidity currents moving down submarine canyons
Shallow Marine SedimentsShallow Marine SedimentsShallow Marine SedimentsShallow Marine Sediments
Deep Ocean Basins of the World
Deep seafloor excluding the continental shelf and slope
From continental rise to mid-ocean ridge
1) Deep ocean sediments are 1) Deep ocean sediments are termed termed pelagicpelagic
2) Pelagic sediments are 2) Pelagic sediments are predominately very fine-grained predominately very fine-grained
3) Two types of pelagic sediments 3) Two types of pelagic sediments
Inorganic clays – from landInorganic clays – from land
Biogenic oozes – from planktonBiogenic oozes – from plankton
4) Two types of biogenic oozes 4) Two types of biogenic oozes
CalcareousCalcareous
SiliceousSiliceous
5) Abundant benthic organisms 5) Abundant benthic organisms crawl over and burrow through crawl over and burrow through the sediment = the sediment = BioturbationBioturbation
Key PointsKey Points
Deep Marine Deep Marine SedimentsSediments
Calcareous Ooze SedimentsCalcareous Ooze Sediments Accumulation of calcium carbonate hard parts from dead microscopic plankton
Mainly consists of cocolithophores and foraminifera tests
Calcite-shelled plankton abundant in warmer surface waters
Accumulate above the Carbonate Compensation Depth (CCD)
cocolithophoresforaminifera
Distribution of Calcareous Ooze Sediments
1) Calcareous oozes principally deposit in relatively shallow, low- to mid-latitude regions of deep ocean
2) Concentrated on tops and flanks of mid ocean ridges
Silica Ooze Sediments Accumulation of silica hard parts from dead plankton
Mainly consists of diatoms and radiolarian tests
Abundant in deeper, cooler surface waters – high latitude
Silica Ooze Sediments Accumulation of silica hard parts from dead plankton
Mainly consists of diatoms and radiolarian tests
Abundant in cooler surface waters – high latitude
Comparing Silica and Carbonate OozesComparing Silica and Carbonate Oozes
Types of Hydrogenous Sediment Sources:Sources: Precipitation of minerals from solution
Material:Material: Carbonates, Metal Oxides and Sulfides
Manganese Nodules
Black Smoker Chimneys
Types of Cosmogenous Sediment Sources:Sources: Extraterrestrial rock, dust ,and debris
Material:Material: Silicates, glass, and metals
Tektite Strewn Fields
Microtektites
Type and Distribution of Marine Sediments
Percentage Distribution of Pelagic Sediments
1) Calcareous OozesCalcareous Oozes = covers 48% of deep seafloor
2) Abyssal ClaysAbyssal Clays = covers 38% of deep seafloor
3) Siliceous OozesSiliceous Oozes = covers 15% of deep seafloor
Rates of Deposition of Marine SedimentsRates of Deposition of Marine Sediments
Total Sediment Thickness in OceanTotal Sediment Thickness in Ocean
MARINE SEDIMENTSMARINE SEDIMENTSDiscussionDiscussion