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Structures and other features within sedimentary rocks
- clues to the past environmentsPaleoenvironments
• Environment of deposition• Direction of water or wind• Strength or energy of transport agent• The “up” side of a sedimentary bed• Life that existed and the environment they
lived in• Climate conditions
Facies
• Set of conditions that lead to a particular rock type or group of rocks.
Chemical Sedimentary Environments
– Shallow marine (salt water) areas (usually carbonates and evaporites form)
– For example – Limestone, Halite, Gypsum
Clastic Sedimentary Environments
• Marine– Beaches, tidal flats, deltas, deep seas,
lagoons.
• Continental– Rivers, deserts, alluvial fans, playa lakes,
glacial areas.
• Transgression – ocean advancing over areas that were once dry land (happening today)
• Regression – opposite, land migrates further out into ocean. (or ocean level dropping)
Typical ocean sediments
beachsand
mud
carbonate
sedimentssand mud
Dissolved ions
Typical ocean sediments
beachsand
mud
carbonate
sediments
Process of transgression
sand mud
carbonate
Typical ocean sediments
beachsand
mud
carbonate
sediments
Process of transgression
sand mud
carbonate
sand mud carbonate
Typical sediment sequence would showCarbonate
Mudsand