A snapshot of the summary - Sedimentology And Stratigraphy
1 introduction: sedimentology and stratigraphy
What processes does sedimentology entail, to what environments does it apply and what does it eventually form?
The study of the processes of formation, transport and deposition of material that accumulates as sediment in continental and marine environments and eventually forms sedimentary rocks.
Of what is stratigraphy the study and how does it relate to sedimentary rocks in dynamic evolving environments?
Stratigraphy is the study of rocks to determine the
order and timing of events in Earth history: it provides the time frame that allows us to interpret sedimentary rocks in terms of dynamic evolving environments.
1.2 sedimentary environments and facies
By what sedimentary structures will a floodplain setting be represented?
The floodplain setting will be represented
by thinly bedded mudrock and sandstone with
roots and other evidence of soil formation.
How can a rock facies be described nad how does it relate to sedimentology and stratigraphy?
A rock facies is a body of rock with specified characteristics that reflect the conditions under which it was formed.
Explain the concept of superposition in a sequence of layered rocks
superposition: ‘in a sequence of layered rocks, any layer is
older than the layer next above it’
Explain what palaeogeography is and think superficial
palaeogeography: the appearance of an area during some time in
2 Terrigenous clastic sediments: gravel, sand and mud
What are terrigenous clastic sediments and sedimentary rocks composed? What practical use do clast size and texture have in the field of sedimentology?
Terrigenous clastic sediments and sedimentary rocks are composed of fragments that result from the weathering and erosion of older rocks. They are classified according to the sizes of clasts present and the composition of the material. Analysis of gravels and conglomerates can be carried out in the field and can reveal where the material came from and how it was transported. The proportions of different clast sizes and the textures of terrigenous clastic sediments and sedimentary rocks can provide information about the history of transport of the material and the environment of deposition.
2.1 Classification of sediments and sedimentary rocks
What is terrigenous clastic material in the field of geology and rocks?
Terrigenous clastic material: This is material that is made up of particles or clasts derived from pre-existing rocks.
What do the terms detrital sediments and siliclastic sediments describe in relation to clasts?
The clasts are principally detritus(waste or debris of any kind)
eroded from bedrock and are commonly made up
largely of silicate minerals.
Sedimentary rocks can be divided into two main branches: clastic and non-clastic. Name the five subcategories and mention if they fall in the clastic, non-clastic or both-category.Clastic:
- Volcaniclastic (tuffs, ignimbrites)
- Terrigenous clastic (mudrocks, sandstones, conglomerates)
- Carbonates (limestones)
- Carbonates (limestones)
- Others (coal, ironstones, phosphates, silicious deposits)
- Evaporites (chemical precipitates)
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