What does sedimentary facies mean in geology?

2020-11-01 by No Comments

What does sedimentary facies mean in geology?

Sedimentary facies, physical, chemical, and biological aspects of a sedimentary bed and the lateral change within sequences of beds of the same geologic age. Sedimentary rocks can be formed only where sediments are deposited long enough to become compacted and cemented into hard beds or strata.

What are facies used for?

Facies are used mostly to establish different units of rock from adjacent units within a contiguous body of rock by physical, chemical, or biological means.

What is a facies boundary?

Facies are transgressive (move shoreward) when. the sediment supply is overwhelmed by a relative rise in the ocean, or when the basin margin subsides tectonically.

What does Microfacies mean?

microfacies (plural microfacies) (petrology) The composition, features, or appearance of a portion of a facies small enough to be examined in thin sections, or in rock samples of similar size.

What is the difference between lithofacies and sedimentological facies?

Facies based on petrological characters (such as grain size and mineralogy) are called lithofacies, whereas facies based on fossil content are called biofacies. Sedimentary facies reflect their depositional environment, each facies being a distinct kind of sediment for that area or environment.

What is a transgression in geology?

A transgression occurs when the rate of sea level rise landward exceeds the rate of sediment input and causes an increase in accommodation, initiating the development of a transgressive surface over which the trangressive sediments of the transgressive systems tract onlap and retrograde.

What is a depositional environment in geology?

A depositional environment is defined as a site where sediments (e.g. detrital, chemical) accumulated, governed by physical, biological, and chemical processes related to modern and applied to ancient environments, and lithified into sedimentary rock units.

Who gave the concept of rock facies?

geologist Amanz Gressly
The term facies was introduced by the Swiss geologist Amanz Gressly in 1838 and was part of his significant contribution to the foundations of modern stratigraphy, which replaced the earlier notions of Neptunism.

What is the process of Retrogradation geology?

1. n. [Geology] The accumulation of sequences by deposition in which beds are deposited successively landward because sediment supply is limited and cannot fill the available accommodation.

What causes a regression geology?

This process is known as regression. Transgressions and regressions may be caused by tectonic events such as orogenies, severe climate change such as ice ages or isostatic adjustments following removal of ice or sediment load. In either case, sea water rises farther up onto land than it did before.