Erosion and Weathering Processes

These flashcards cover key concepts regarding erosion, sedimentation, weathering processes, and the geological significance of basins as discussed in the lecture.

Gravity Erosion

The primary driver of erosion in high tops, causing sediment to accumulate in basins.

Basin Formation

A basin is formed through subsidence, where sediment accumulates.

Permeability

The ability of sediments to allow fluids to pass through, affected by sediment source, basin type, and maturity.

Physical Weathering

The disintegration of older rocks into smaller particles without chemical alteration, e.g., freeze-thaw cycles.

Insolation Weathering

Weathering due to differences in heat; the exterior of a rock heats more than the interior, causing thermal expansion and contraction, leading to fractures.

Sedimentary Basin

A large depression in the Earth's crust, often formed by tectonic activity, where sediments accumulate.

Tectonic Settings

Different geological types of basin formation, including intracratonic, passive margin, convergent, and transform boundaries.

Salt Weathering

The process where salts crystallize in pore spaces or fractures, causing increased pressure and rock breakdown.

Wet/Dry Cycles

An alternating process of wetting and drying that leads to rapid breakdown of soft rocks.

Spheroidal Weathering

A type of physical weathering characterized by the breakdown of rocks into rounded shapes.

Chemical Weathering

The chemical alteration of minerals through reactions, such as hydrolysis, oxidation, and reduction.

Hydrolysis

A chemical weathering process where acid water reacts with minerals, particularly clays.

Biological Weathering

Weathering caused by living organisms, such as plant roots breaking apart rocks and microbial activity altering chemical composition.

Lithification

The process through which unconsolidated sediments are transformed into solid rock, primarily via compaction and cementation.

Compaction

A component of lithification where the weight of overlying layers reduces the volume of sediments and squeezes out pore fluids.

Cementation

A component of lithification where minerals precipitate in pore spaces, acting as a glue that binds sediment grains together.

Sediment Transport

The movement of particles through a medium (water, air, or ice), categorized by mechanisms such as suspension, saltation, and traction.

Traction

A transport mechanism where large or heavy particles are rolled or dragged along the bottom of a flow.

Carbonation

A specific type of chemical weathering where rainwater reacts with CO{2} to produce carbonic acid (H{2}CO_{3}), which dissolves minerals like calcite.

Oxidation

A chemical weathering process where minerals react with oxygen, often recognized by the 'rusting' or reddening of rocks containing iron.

Porosity

The ratio of the volume of voids to the total volume of a rock or sediment, represented as \phi = \frac{V{v}}{V{t}}.

Sorting

A measure of the uniformity of grain sizes within a sediment; well-sorted sediments have a narrow range of sizes, while poorly sorted sediments have a wide range.

Diagenesis

The collective physical, chemical, and biological changes that occur in a sediment after its initial deposition and during/after its transformation into rock.

Suspension

A mode of transport for very fine particles (clay/silt) that are held up by the turbulence of a moving fluid.

Saltation

A transport mechanism where medium-sized particles (sand) move in a series of leaps or bounces along the bed.

Provenance

The geographic and tectonic source area from which sedimentary materials are derived.

Hydration

A chemical weathering process where water is added to the crystal structure of a mineral (e.g., converting Anhydrite to Gypsum).

Sediment Maturity

The degree to which a sediment has been physically and chemically modified; textural maturity refers to sorting/rounding, while compositional maturity refers to the removal of unstable minerals.

Intracratonic Basins

Basins located within the stable interior of a continental plate, formed by slow subsidence far from plate boundaries.

Passive Margin Basins

Basins occurring on the trailing edge of continents, formed by thermal subsidence and sediment loading after continental rifting.

Convergent Margin Basins

Basins associated with subduction zones or collisions, including trench, fore-arc, back-arc, and foreland basins.

Transform (Pull-Apart) Basins

Small, deep basins formed along strike-slip faults where bends or offsets in the fault cause crustal extension and subsidence.