Deltaic Clastics Flashcards

1
Q

What is a delta?

A

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.

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2
Q

Describe the deltaic process from topset beds

A
rivers enters lake or ocean
velocity decreases
sediment deposited
distributary channels formed
delta progrades offshore
coarsening upward sequence in profile
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3
Q

What is a topset bed?

A

a horizontal layer of coarse sand and gravel deposited on top of a delta

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4
Q

what is a foreset bed?

A

an inclined layer of sand a gravel deposited along the leading edge of a delta

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5
Q

what is a bottomset bed?

A

a fine, horizontal layer of clay and silt deposited beyond the edge of a delta

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6
Q

What are the 2 types of deltas and what is included in those categories?

A
  1. Constructive
    - river dominated
  2. Destructive
    • Wave dominated
      - Tide dominated
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7
Q

Can deltas switch lobe placement over time?

A

YESS

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8
Q

What is an example of a delta that switched lobes over time?

A

Mississippi River

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9
Q

What is a delta plain?

A

RIVER PROCESS DOMINATE: usually contain coarse distributary channels and tidal flat deposits

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10
Q

What is a delta front?

A

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.

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11
Q

What is a pro-delta?

A

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

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12
Q

Example of a river dominated delta? what

A

Mahakan river-dominated delta (Indonesia)

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13
Q

How much hydrocarbon does the Mahakam river-dominated delta contain and when did production start?

A

3 billion barrels if oil and 30 tcf of gas. Production started in 1988.

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14
Q

Belly River Group is an example of what kind of sequence?

A

Deltaic Sequence CUS

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15
Q

Do Deltas coarsen upwards or downwards?

A

UPWARDS!!

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16
Q

What are the kinds of hydrocarbon occurrences and trapping mechanisms in deltaic environments?

A
  1. OCS: Outer continental Shelf

2. Progradational Basin Fill

17
Q

What is am example of outer continental shelf trapping mechanism and a progradational basin fill in a deltaic environment?

A

OCS: Northern Gulf of Mexico (18.75 billion barrels oil, 177 TCF gas)

progradational: Middle Pennsylvanian red fork SST in the Anadarko Basin
1,416 MMBoil, 23.7 TCF gas