Test 2 Flashcards
ocean sediments
solid, mineral or organic in origin; deposits of insoluble particles that have accumulated on the seafloor
How are ocean sediments transported?
Water, air, ice then deposited
How are rocks transported?
by river and deposited into the sea
Size of sediments control the …
erosion (renewal), transport (lateral), deposition
What are the different types of erosion occurs in solutions?
evaporation, chemical reactions, organisms
What is the size of sediments from biggest to smallest?
boulder, cobbles, pebbles, granules, sand, silt, clay
sediment
Loose particles of rock, mineral, or biological material that accumulate on the seafloor or other surfaces, transported and deposited by wind, water, ice, or biological processes.
lithogenic sediment
Sediment derived from the weathering and erosion of rocks, typically composed of mineral grains.
Terrigenous Sediment
Derived from land sources through weathering, erosion, and transported by rivers, wind, or glaciers to the ocean.
Clastic Sediment
Made of fragments of pre-existing rocks or minerals, often carried by water, wind, or ice.
Detrital Sediment
Similar to clastic, a broader term that refers to sediment composed of solid particles derived from the breakdown of pre-existing rocks. It includes all clastic sediments but can also include some materials like volcanic ash or mineral grains that are not necessarily transported as solid fragments, consisting of solid particles from weathered rocks.
Volcanogenic Sediments
Sediments formed from volcanic activity, including ash, lava fragments, and pumice, often carried into the ocean by wind or water.
Cosmogenic Sediments
Sediments originating from space, including micrometeorite dust and tektites, which accumulate slowly on the ocean floor.
Biogenic Sediment
Sediment composed of the remains of marine organisms, primarily shells and skeletal material made of calcium carbonate (CaCO₃) or silica (SiO₂).
Active Biogenic Sediment
Actively accumulating organic material, often in areas of high biological productivity.
Passive Biogenic Sediment
Older, less biologically active material that has settled in deeper ocean areas.
Passive Biogenic Sediment
Older, less biologically active material that has settled in deeper ocean areas.
Hydrogenic Sediments
Sediments formed from the precipitation of dissolved minerals in seawater, such as manganese nodules, evaporites, and phosphorites.
Erosion
The process of breaking down and removing sediments or rock material by water, wind, ice, or gravity.
Transportation
The movement of sediment from one place to another by agents like water currents, waves, wind, or ice.
Deposition
The process by which transported sediments settle and accumulate in a new location, such as the seafloor.
Sorting
The process by which sediments are separated based on size, shape, or density during transportation.
Well-Sorted
Sediment composed of particles of a uniform size, typically found in environments with consistent energy conditions, such as beaches or dunes.
poorly sorted
Sediment composed of particles of varying sizes, often deposited in environments with fluctuating energy levels, such as glacial or high-energy river settings.
Hjulstrom Diagram
A graph that shows the relationship between particle size and the velocity of water needed to erode, transport, or deposit sediments. It helps explain why some fine sediments require higher velocities to erode due to cohesion.
Inertia
The resistance of sediment particles to changes in motion. Larger particles have more inertia and require more energy to move.
Minimum Velocity to Erode
The lowest water velocity required to lift sediment particles from the seabed and put them into motion.
Maximum Velocity to Deposit
The highest velocity at which a moving sediment particle will settle and be deposited rather than remain in suspension.
Cohesive
Describes fine-grained sediments, like clay and silt, that stick together due to electrostatic forces, making them harder to erode compared to larger, non-cohesive particles.
Settling Velocity
The speed at which a sediment particle falls through water, determined by its size, shape, and density, as well as water viscosity.
Lamellar Flow (Laminar Flow)
A smooth, orderly flow of water in parallel layers, with minimal mixing between them. Common in slow-moving water.
Turbulent Flow
A chaotic and irregular flow of water with swirling motion and mixing, which enhances sediment transport. Found in fast-moving currents and rivers.
Eddies
Swirling currents of water that form within turbulent flow, often causing localized mixing and influencing sediment transport.
Fluid Density
The mass of a fluid per unit volume, which affects the ability of water to transport sediment. Higher-density fluids, like seawater, can carry more sediment than freshwater.
Solution
A mode of sediment transport where dissolved minerals are carried in water, often contributing to chemical sediment deposition.
Suspension
A transport mode in which fine sediment particles (such as silt and clay) are carried within the water column without settling quickly.
Saltation
A transport process in which medium-sized sediment particles (such as sand) bounce or skip along the seabed as they are lifted and dropped by water currents.
traction
A mode of sediment transport where large particles, such as pebbles and cobbles, are rolled or dragged along the seabed by strong currents.
Competency
The maximum particle size that a fluid (such as water) can transport; determined by the velocity and energy of the moving water.
Capacity
The total amount of sediment that a fluid can carry at a given time, depending on flow strength and sediment availability.
Load
The total amount of sediment transported by a river or ocean current, which can be carried in solution, suspension, saltation, or traction.
Flocculation
The process by which fine-grained particles, such as clay, clump together due to chemical interactions (like saltwater mixing with freshwater), increasing their size and causing them to settle faster.
Ions
Electrically charged atoms or molecules dissolved in seawater, contributing to chemical sediment formation and ocean salinity.
Salts
Compounds formed from the combination of positive and negative ions, such as sodium chloride (NaCl), that contribute to seawater salinity and can precipitate as sediment.
Bioagglomeration
The process by which biological activity causes sediment particles to clump together, often forming biogenic sediments or contributing to the formation of oozes.
Ice Rafting
The transport of sediments by floating ice (glaciers or icebergs), which later melt and deposit the carried material in the ocean.
Productivity
The rate at which marine organisms, such as phytoplankton, produce organic matter, influencing the accumulation of biogenic sediments on the seafloor.
Chemical Stability
The tendency of a mineral or compound to remain unchanged under specific environmental conditions, affecting its dissolution or preservation in ocean sediments.
Calcite
A mineral form of calcium carbonate (CaCO₃), commonly found in marine sediments and making up the shells of many marine organisms.
Aragonite
A less stable, but structurally different, form of calcium carbonate (CaCO₃) compared to calcite, often found in coral skeletons and some mollusk shells.
Silica
A mineral composed of silicon dioxide (SiO₂), commonly found in marine sediments from the skeletal remains of diatoms and radiolarians.
Apatite (Calcium Phosphate)
A phosphate mineral (Ca₅(PO₄)₃) found in marine sediments, often derived from fish bones, teeth, and other biological sources.
Oozes
Deep-sea sediments composed of at least 30% biogenic material, primarily made of silica (from radiolarians and diatoms) or calcium carbonate (from foraminifera and coccolithophores).
Aragonite Compensation Depth (ACD)
The depth in the ocean below which aragonite dissolves faster than it accumulates, preventing its long-term preservation in sediments.
Calcite Compensation Depth (CCD)
The depth (~4,500 meters) below which calcite dissolves more quickly than it accumulates, preventing carbonate-rich sediments from forming.
Silica Compensation Depth (SCD)
The depth at which silica dissolution equals its accumulation, controlling the distribution of siliceous sediments on the ocean floor.
Red Clay
A fine-grained deep-sea sediment primarily composed of wind-blown dust, volcanic ash, and small amounts of biogenic material, accumulating in areas with low biological productivity.
Authigenic Sediments
Sediments that form in place through chemical reactions within seawater or sediments, such as manganese nodules and phosphorites.
Evaporites
Minerals that precipitate from seawater due to evaporation, including salts like gypsum and halite, typically found in shallow, enclosed marine environments.
Manganese Nodules
Rounded deposits of manganese, iron, and other metals that form slowly on the deep-sea floor through chemical precipitation from seawater.
Rare Earth Elements (REEs)
A group of valuable metallic elements (like neodymium and yttrium) that accumulate in deep-sea sediments, often found in association with manganese nodules.
Phosphate Nodules
Rock-like deposits of calcium phosphate that form on the ocean floor, often in areas of high biological productivity where organic matter decomposes and releases phosphorus.
What are the various types of ocean sediments?
Lithogenic, biogenic, hydrogenic, cosmogenic
How are lithogenic sediments derived, distributed, and found near?
Derived from rocks, transported by rivers, wind, ice, or volcanic activity. Found near continental margins and deep-sea basins.
How are biogenic sediments derived, distributed, and found near?
Composed of organic material from marine organisms (e.g., calcareous & siliceous oozes). Found in areas of high biological productivity.
How are hydrogenic sediments derived, distributed, and found near?
Formed by precipitation of minerals from seawater (e.g., evaporites, manganese nodules). Found in isolated basins or deep-sea environments.
How are cosmogenic sediments derived, distributed, and found near?
Dust and debris from space, widely dispersed in small quantities.
How does particle size effect the Relationship of Erosion, Transportation & Deposition?
Larger particles require stronger forces to be transported and settle quickly.
How does turbulence effect the Relationship of Erosion, Transportation & Deposition?
Stronger currents suspend and move finer particles further.
How does settling velocity effect the Relationship of Erosion, Transportation & Deposition?
Larger and denser particles settle faster, while smaller ones remain suspended longer.
types of laminar flow and their differences
Laminar Flow – Smooth, parallel flow with minimal mixing; occurs in slow-moving water.
Turbulent Flow – Chaotic, irregular motion that keeps fine sediments in suspension.
Eddies – Circular currents caused by turbulence, affecting sediment transport.
what Factors Controlling Fluid Density?
temperature, salinity, pressure
How does temperature, salinity, and pressure affect fluid density?
Temperature – Cold water is denser than warm water.
Salinity – Higher salinity increases density.
Pressure – Greater depth increases density due to compression
What Factors control Settling Velocity?
particle size, density, shape, water viscosity
How does particle size, density, shape, and water viscosity control settling velocity?
Particle Size – Larger particles settle faster.
Density – Heavier particles sink more quickly.
Shape – Spherical particles settle faster than irregularly shaped ones.
Water Viscosity – Warmer water reduces settling velocity
What Ways in Which Water Transports Sediments?
Solution – Dissolved minerals transported in water.
Suspension – Fine particles carried without settling.
Saltation – Medium-sized particles bounce along the seafloor.
Traction – Large particles roll or drag along the bottom.
How is Clay removed from the Marine Environment?
Removed by flocculation (clumping of particles) or settling in low-energy environments.
in what Ways Lithogenic Sediment is Transported into the Ocean
Rivers – Major source of terrigenous sediment.
Wind – Carries fine dust and volcanic ash.
Ice Rafting – Glaciers transport and drop sediments as they melt.
Gravity Flows – Turbidity currents carry sediment downslope.
Controls on the Distribution of Oozes in the Ocean Basin
Productivity – More biological activity = more biogenic sediment.
Dissolution Rates – Oozes accumulate where dissolution is minimal.
Depth – Below the CCD, calcareous oozes dissolve.
Why Size Matters in Sediment Deposition & Erosion
Larger particles require stronger forces for movement and settle quickly.
Smaller particles stay suspended longer and are easily eroded.
Carbonate Compensation Depths & Stability of Aragonite vs. Calcite
Aragonite dissolves at shallower depths (ACD) because it is less stable than calcite.
Calcite dissolves at deeper depths (CCD), around 4,500 meters.
CO₂ levels and acidity increase with depth, causing dissolution.
Factors Controlling the Depth of the CCD
Water Chemistry – Higher CO₂ and acidity at depth dissolve carbonates.
Temperature & Pressure – Cold, deep water promotes dissolution.
Supply of Carbonate Material – More carbonate input raises the CCD.
Distribution of Sediment Types in Terms of Abundance
Near Coasts – Lithogenic sediments dominate.
Deep Ocean – Biogenic sediments (oozes) and red clay are most common.
Hydrothermal & Hydrogenic Areas – Authigenic sediments like manganese nodules.
Formation of Red Clay Deposits
Found in low biological productivity areas below the CCD.
Consists of wind-blown dust, volcanic ash, and cosmic debris.
Settles slowly in the deep ocean basins.
Layering of Deep-Ocean Sediments in the Atlantic & Pacific Oceans
Pacific Ocean – Deeper, colder, and more acidic → more red clay and siliceous oozes.
Atlantic Ocean – Shallower, less acidic → more calcareous oozes.
Layering is controlled by ocean depth, productivity, and dissolution rates.
Most Common Sediments in Different Parts of the Ocean
Continental Shelf – Lithogenic sediments from rivers.
Mid-Ocean Ridges – Biogenic oozes (calcareous & siliceous).
Abyssal Plains – Red clay and hydrogenic deposits.
Upwelling Zones – Siliceous oozes from high productivity.
Formation of Hydrogenic Deposits
Evaporites – Form when seawater evaporates, leaving behind salts (e.g., halite, gypsum).
Manganese Nodules – Form over millions of years by slow precipitation of metals.
Phosphate Deposits – Accumulate where organic material decomposes, releasing phosphorus.
