Turbidity currents and turbidites Flashcards
what is a turbidity current?
its a type current that flows down a subaqueous slope along the bottom of a lake or ocean and carries a mixed mass of sediment
what are turbidites?
they are deposits made by a turbidity current, typically with graded bedding
what are the triggers for a turbidity current?
earthquakes or overloading and failure of sediments
or
storm related flow of sand and mud into canyon heads
or
bedload inflow from rivers and glacial meltwater (into lakes)
what propels the energy for a turbidity current?
Gravity. Not water.
what are the parts of a turbidity current?
body, neck, head and drag
how do turbidity currents move?
they may move as surges or as steady, uniform flows
what are the two types of turbidity current deposits?
high density flow and low density flow
what does the high density flow deposits consist of?
thick deposits, containing coarse grain sandstones or gravels
what does the low density flow deposits consist of?
thin deposits, finer-grained
in a turbidite, what do the graded beds represent?
a single, short-lived turbidity current flow event. this is called a chronostratigraphic unit
Continental margin deep-sea settings are dominated by which two types of sediments
Siliciclastic Sediment
or
Pelagic Sediment
Characteristics of a Turbidite
Poorly sorted
Fining upwards
have a poured-in appearance
a Bouma Sequence’s graded bedding is often completely lacking what?
Lamination (eg: basal conglomerate in Rader Turbidite)
A bouma sequence reflects what type/kind of flow regime?
a decreasing flow regime from bottom to top
A bouma sequence’s sedimentary structures may include what?
flute casts on the lower surfaces of sandstone
