Sequence Stratigraphy

Question 1

Sequence or depositional sequence?

Answer 1

A stratigraphic unit composed of a relatively conformable succession of genetically related strata and bounded at its top and base by unconformities or their correlative conformities. Not recognized as formal strat. units.

Question 2

Formula of Accommodation space?

Answer 2

dAC = deustacy + dsubsidence + dcompaction

d=delta

Question 3

Accommodation space?

Answer 3

The amount of space available for sediment to accumulate at any point of time and is controlled by subsidence rate and eustacy

Question 4

Eustasy?

Answer 4

Is measured between the sea-level surface and a fixed datum (usually the centre of the earth)

Question 5

Name the different types of systems tracts?

Answer 5

Highstand systems tract (HST) = sediment deposited during high sea level

Falling stage systems tract (FSST) = sediment deposited as sea falls from high to low

Lowstand systems tract (LST) = sediment deposited during low sea level and early rising sea level

Transgressive Systems Tract (TST) = sediment deposited during rising sea level

Parasequence - a relatively conformable succession of genetically related beds or bedsets (within a parasequence set) bounded by marine flooding surface and their correlative surfaces

Marine flooding surface: A surace that seperates younger from older strata, across which there is evidence of an abrupt increase in water depth

Question 6

Type 1 sequence boundary?

Answer 6

• Result of subaerial exposure and sea level drop below the shelf margin
• associated with stream rejuvenation and down cutting (erosion)
• basinward shift in facies
• downwards shift in coastal onlap
• relative sea level fall

Question 7

Type 2 sequence boundary?

Answer 7

-Marked by subaerial exposure and a downward shift in costal onlap landward at the depositional-shoreline break
-no subaerial erosion associated with stream rejuvination and down cutting
occurs when sea level does not fall belwo the shelf maring