Sedimentary Rocks - L25- Flashcards

1
Q

What does SSR stand for

A

Sedimentary stratigraphic record

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2
Q

Thickness of sediments across the world

A

0.82-20km

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3
Q

Problems with the SSR

x3

A

1) incomplete
2) Not always precise dates for the units studied
3) Not a continuous record

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4
Q

Accommodation Space

A

The volumetric space within which sediment can accrue

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5
Q

What does deposited sediment equal when the accommodation space is larger than the sediment supply?

A

Sediment supply

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6
Q

What is deposited sediment equal to when the supply of sediment is larger than the accommodation space?

A

The accommodation space

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7
Q

What sedimentary condition is found within the rock record

  • so which rocks do we see
A

Depositional = aeolian and carbonate

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8
Q

Which rocks do we not see in the sedimentary record?

A

Erosional - so glacial and alluvial

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9
Q

What 3 things do we need to get ancient rocks for modern analysis

A

1) Accommodation space
2) Basins
3) Post-depositional Survival (as even now ancient but exposed sedimentary rocks are being eroded)

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10
Q

What is accommodation space filling dictated by

A

base level

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11
Q

What is base level

A

The level above which deposition is temporary and erosion occurs

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12
Q

What is a diachronous facies

A

The same sediment deposited at different points at different times

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13
Q

Walther’s Law

A

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

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14
Q

Oldest Sedimentary rock in Britain

A

Mesoproterozoic

  • Meall Dearg Formation - Scotland
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15
Q

Why is it harder to rpedict the shape of the continents and tectonic plates after the Permian

A

Subduction zones have destroyed the continent or oceans - don’t know when continent became ocean plates etc

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16
Q

Allogenic Processes

A

External to the system - climate and tectonics and leave sedimentary and geomorphic signatures

e.g Earthquakes, floods, waves, sea level

17
Q

Autogenic Processes

A

Pattern formation arises from how they were made - from growth

e.g Dune migration, River avulsion, Delta Growth

18
Q

Sadler Effect - 1981

A

The rate of sedimentation is more difficult to ascertain due to erosion

  • the gaps skew the record of time and so understanding the parts missing is just as important