Sedimentary Rocks - L25- Flashcards
What does SSR stand for
Sedimentary stratigraphic record
Thickness of sediments across the world
0.82-20km
Problems with the SSR
x3
1) incomplete
2) Not always precise dates for the units studied
3) Not a continuous record
Accommodation Space
The volumetric space within which sediment can accrue
What does deposited sediment equal when the accommodation space is larger than the sediment supply?
Sediment supply
What is deposited sediment equal to when the supply of sediment is larger than the accommodation space?
The accommodation space
What sedimentary condition is found within the rock record
- so which rocks do we see
Depositional = aeolian and carbonate
Which rocks do we not see in the sedimentary record?
Erosional - so glacial and alluvial
What 3 things do we need to get ancient rocks for modern analysis
1) Accommodation space
2) Basins
3) Post-depositional Survival (as even now ancient but exposed sedimentary rocks are being eroded)
What is accommodation space filling dictated by
base level
What is base level
The level above which deposition is temporary and erosion occurs
What is a diachronous facies
The same sediment deposited at different points at different times
Walther’s Law
The transition between layers found in vertical-based deposits, where there is no break in succession, are the ones that are also found in laterally adjacent depositional environments
Oldest Sedimentary rock in Britain
Mesoproterozoic
- Meall Dearg Formation - Scotland
Why is it harder to rpedict the shape of the continents and tectonic plates after the Permian
Subduction zones have destroyed the continent or oceans - don’t know when continent became ocean plates etc