What is progradation in geology?

Progradation is the diagnostic depositional trend for regressions, and is defined as the building forward or outward toward the sea of a shoreline or coastline (as of a beach, delta, or fan) by nearshore deposition of river-borne sediments or by continuous accumulation of beach material thrown up by waves or moved by …

What is progradation process?

In sedimentary geology and geomorphology, the term progradation refers to the growth of a river delta farther out into the sea over time. This occurs when the volume of incoming sediment is greater than the volume of the delta that is lost through subsidence, sea-level rise, or erosion.

What are Clinoforms?

A clinoform is a two-dimensional surface with a sigmoidal (sloped) geometry that is characteristic of basin margin strata. They are timelines that represent a moment in geological time.

What is a Prograding shoreline?

Definition of Prograding coast: A coast where sediment is deposited, such that the shoreline is shifting seaward.

What is fining upward sequence?

Fining- and coarsening-upward sequence Fining upward sequence means that the grain size is decreasing upward, whereas coarsening upward means that the grain size is increasing upward.

What is Parasequence in geology?

A parasequence is a set of relatively conformable, genetically interrelated rock strata or stratal set that is bounded by marine flooding surfaces and their correlatable interfaces.

What happens during retrogradation?

Retrogradation is a reaction that takes place when the amylose and amylopectin chains in cooked, gelatinized starch realign themselves as the cooked starch cools.

What is difference between retrogradation and gelatinization?

The key difference between gelatinization and retrogradation is that gelatinization refers to the act of making or becoming gelatinous, whereas retrogradation refers to the motion in a retrograde manner. The terms gelatinization and retrogradation describe the properties of starch.

What causes retrogradation of starch?

When starch is heated in the presence of water and subsequently cooled, the disrupted amylose and amylopectin chains can gradually reassociate into a different ordered structure in a process termed retrogradation.

What is Aggrading river?

Aggradation (or alluviation) is the term used in geology for the increase in land elevation, typically in a river system, due to the deposition of sediment. Aggradation occurs in areas in which the supply of sediment is greater than the amount of material that the system is able to transport.

What does it mean for a delta to prograde?

Delta deposits prograde or advance their edges into the ocean. Because the coarsest sediments are deposited closest to the river mouth, and the finest ones farthest away, the general stratigraphy of a delta environment shows a coarsening upward sequence.

What causes fining upward sequence?

It is generally found in River point bars and Sand deposited by a turbidity flow, where there is less disturbance and more settling time. In basins, the larger (denser) grains settle first and gradually the smaller grains and finally sand, silt and clay settle to form the fining upwards sequence.

What causes coarsening upward?

Mostly, alluvial fan deposits have strongly developed thickening and coarsening-upward succession, which are caused by active fan progradation or outbuilding. But there are some fan deposits have thinning and finning upward succession which are caused by fan retrogradation.

How do you identify a parasequence?

In some cases, fining-upwards parasequences can be recognized. For example, in marginal-marine settings, the base of the parasequence may be marked by the abrupt appearance of marine sand above marginal-marine muds, above which the percentage of sand decreases and the sand beds become thinner.

What is Highstand system tract?

The highstand systems tract is between the maximum flooding surface and the overlying sequence boundary. Highstand systems tracts show a progradational stacking pattern due to sediment supply exceeding the accommodation space. Progradation results in basinward downlapping onto the maximum flooding surface.

What is an example of retrogradation?

When starchy foods—rice, pasta, bread dough—are cooked in the presence of water, all those individual granules of starch absorb water and swell up. The amylose and amylopectin molecules in the granules, formerly clinging together, relax a bit and come apart, allowing water to seep in among them.