Sequence Stratigraphy Flashcards
What does it mean to say that facies are retrogradational?
If sea level rises faster than sediment is supplied, the coastline shifts landward: this is known as transgression and the pattern in the sediments is retrogradational
What is progradational?
If sediment is supplied to a coast where there is no (or relatively slow) sea‐level rise the coastline moves seaward: this is regression and the sediment pattern is progradational.
What is aggradational
A situation where the coastline stays in the same position for long periods of time is relatively unusual and requires a balance between relative sea‐level rise and sediment supply producing a pattern of aggradation in the sediments.
What is the maximum flooding surface?
When transgression ceases and the shoreline initially remains static and then starts to move seawards. It can be identifies by the furthest point of landward extent of the shore line
The maximum flooding surface divides which two system tracts?
Highstand and transgressive
What is a ravinement surface? How does it form?
surfaces of erosion formed during transgression, they form because high wave energy in the shallow water that floods over the land surface can result in erosion
What is a parasequence?
packages of beds deposited as a consequence of the creation of a small amount of accommodation that is then filled up by sediment.
What triggers the start of new parasequence
a facies shift from shallower to deeper water deposition
What is the surface called that divides two parasequences
flooding surface
What is the facies pattern within an individual parasequence?
progradational
What is the definition of “sequence stratigraphy
The study of the relationships between sea level changes and sedimentation
What forms the upper and lower boundaries of a sequence
An unconformity caused by erosion called a sequence boundary
What is transgression
During a relative sea‐level rise, the shoreline will move landward
What is regression
Movement of the shoreline seawards as a result of sedimentation occurring at the coast
What is forced regression
seaward movement that is due to a relative sea‐level fall