What causes Flaser bedding to form?
Flaser beds are a sedimentary, bi-directional, bedding pattern created when a sediment is exposed to intermittent flows, leading to alternating sand and mud layers. Individual sand ripples are created, which are later infilled by mud during quieter flow periods.
Where is Flaser bedding found?
Flaser and wavy bedding were found in two ephemeral stream deposits: the Jurassic Kayenta Formation and the modern wash in Seven Mile Canyon, both located in southeastern Utah, USA. These examples demonstrate that flaser bedding can form and be preserved in ephemeral streams.
What is wavy bedding?
Wavy bedding occurs when mud is deposited over the whole area of a bed of rippled and/or cross stratified sand. It usually loosely follows the alternating concave-convex nature of the ripples creating a wavy appearance.
How is lenticular bedding formed?
Lenticular bedding is a sedimentary bedding pattern displaying alternating layers of mud and sand. Formed during periods of slack water, mud suspended in the water is deposited on top of small formations of sand once the water’s velocity has reached zero.
What is a sedimentary Bedform?
Bedforms are primary sedimentary structures; structures that form at the time of deposition of the sediment in which they occur and they reflect some characteristic(s) of the depositional environment.
What is trough cross bedding?
Trough cross-beds have lower surfaces which are curved or scoop shaped and truncate the underlying beds. The foreset beds are also curved and merge tangentially with the lower surface. They are associated with sand dune migration.
What is the difference between a dune and a ripple?
The main difference between a ripple and dune is size, with dunes being taller than about 10 cm. Sometimes tiny ripples form on silty sediment, and larger dunes form where very fast water currents flow over gravel. Ripples and dunes are useful because they are fairly commonly preserved in the sedimentary record.
What kind of bedding is a flaser bed?
Flaser bed. Flaser bedding, vertical section. Flaser beds are a sedimentary, bi-directional, bedding pattern created when a sediment is exposed to intermittent flows, leading to alternating sand and mud layers.
When does a flaser bed form in a stream?
Flaser bedding, vertical section. Flaser beds are a sedimentary, bi-directional, bedding pattern created when a sediment is exposed to intermittent flows, leading to alternating sand and mud layers. While flaser beds typically form in tidal environments, they can (rarely) form in fluvial conditions – on point bars or in ephemeral streams.
Which is the best definition of a flaser?
Definition of flaser. : an irregular usually streaked lens of granular texture found in a micaceous interstitial mass of rock and produced by shearing and pressure during metamorphism.
How long does it take for a flaser bed to consolidate?
These mud drapes are typically a minor constituent of the deposit; they can consolidate within three hours, protecting the underlying layer from erosion. Flaser bedding typically forms in high-energy environments but some have also been described in turbiditic sediments reworked by contour currents (Rebesco, 2014).
