Marine Environments of DepositionQuiz 3

1. What sedimentary setting is most likely to create overpressure by compaction?

A. Muddy deltas (deposition is too fast to allow compaction)

2. In what kind of sedimentary environment do evaporate (salt) deposits form?

A. Deserts

3. Walter’s law of sedimentation

A. When depositional environments migrate laterally, sediments of one environment come to lie on top of sediments of an adjacent environment

• :

Outline

• Delta Environment

• Progradation

• Deep water environments

– Continental slopes and turbidites

• Near shore environments

– Barrier Islands

– Reefs, Tidal flats

– Carbonate Platforms

Deltas: Continental/Marine interface

(Sand + silt)

(Silt + Clay)

(Shale)

Delta Migration Deltas: Continental/Marine interface

(Sand + silt)

(Silt + Clay)

(Shale)

Fluvial (river) Stacking

Delta Stacking Mississippi Delta

Gulf of Mexico Deep Water

Gulf of Mexico PlatfomsSubmarine canyons and

fans on New Zealand slope and rise

Courtesy of Clark Alexander

Turbidites

TurbiditeSands

• Can form very thick piles of sandstone reservoir

Deposition events tied to hurricanes

Garrison et al. 2013 19

Gum Hollow DeltaTexas

Turbidite channels and Fan in 3D Seismic slice-North Sea

Fans

Barrier Islands

21

Shallow shelf

Lagoon

Land Ocean

Barrier Islands

LongshoreCurrents Sea level

change and the stacking of rocks

Stacking Patterns

26

Progradation

Retrogradation

Ancient Beach

Deposit, Utah

Carbonate Reefs

Atoll Reef Evolution Carbonate Reservoirs

32

Leduc Reef Reservoirs

Geoexpro vol.9, 2013 – Leduc Reef, Alberta, Canada33

Carbonate Shoals - Clastics

35Potential Reservoir

Tidal Flat DepositsSeals and Source rocks- Sometimes include evaporates (salt)

Take home points• The vertical stacking of sedimentary rocks reflects

the lateral change of the sedimentary system

• Fining upwards is caused by decrease of the energy of the system: this can result from flooding or slowing down of the transport medium

• High energy systems often make good reservoirs

• Low energy systems make good source rocks

• Sedimentary environments have their distinctive distribution of rock types