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