Deltaic Clastics Flashcards
What is a delta?
a deposit of sediment formed at the mouth of a river where it enters a standing body of water such as a lake or ocean.
Describe the deltaic process from topset beds
rivers enters lake or ocean velocity decreases sediment deposited distributary channels formed delta progrades offshore coarsening upward sequence in profile
What is a topset bed?
a horizontal layer of coarse sand and gravel deposited on top of a delta
what is a foreset bed?
an inclined layer of sand a gravel deposited along the leading edge of a delta
what is a bottomset bed?
a fine, horizontal layer of clay and silt deposited beyond the edge of a delta
What are the 2 types of deltas and what is included in those categories?
- Constructive
- river dominated - Destructive
- Wave dominated
- Tide dominated
- Wave dominated
Can deltas switch lobe placement over time?
YESS
What is an example of a delta that switched lobes over time?
Mississippi River
What is a delta plain?
RIVER PROCESS DOMINATE: usually contain coarse distributary channels and tidal flat deposits
What is a delta front?
is the site of much of the active deposition in deltaic environments, particularly at the mouth of the distributary where coarse sediment is deposited in distinct distributary mouth bars.
What is a pro-delta?
BASINAL PROCESSES DOMINATE: is the are where fine mud and silt settle out of suspension and merge seaward with fine grained sediment of the basin floor
Example of a river dominated delta? what
Mahakan river-dominated delta (Indonesia)
How much hydrocarbon does the Mahakam river-dominated delta contain and when did production start?
3 billion barrels if oil and 30 tcf of gas. Production started in 1988.
Belly River Group is an example of what kind of sequence?
Deltaic Sequence CUS
Do Deltas coarsen upwards or downwards?
UPWARDS!!