Deep Sea Fan Systems
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Transcript of Deep Sea Fan Systems
Deep Sea Fan Systems
Deep-sea Fan Setting
Deep-sea fans occur primarily at the base of continental shelves and are often associated with shelf canyons.
Deep-sea fans are dominated by two facies associations: channel cut-and-fill deposits with well-developed levees in the upper to mid fan and channelized turbidite deposits in the distal fan.
Facies Models
Shanmugam 2000
Feeder Channels
Turbidites (density/gravity flows)
Bouma Sequence
Photo by W. W. Little
Photo by W. W. Little
Flute Casts
Photo by W. W. Little
Photo by W. W. Little
Tool Marks
Photo by W. W. Little
Bioturbation
Photo by W. W. Little
Photo by W. W. Little
Dish Strucures
Dish structures are subaqueous water-escape features formed during rapid deposition of sand.
Convoluted Bedding
Photo by W. W. Little
Laminated/Massive/Bioturbated Mud
Photo by W. W. Little
Photo by W. W. Little
Chert
Delta-front Turbidites
Because of the large quantity of sediment deposited by rivers as they enter the sea and its stacking to produce a relatively steeply-sided platform, turbidites are common features associated with deltas.
Bouma Sequence Variations
Figures 6 & 7: Sandstone Depositional Environments, Memoir 31 AAPG
Figure 4: Idealized facies model. http://www.eu-seased.net/services/issue2/img9.gif
Shanmugam 2000
Geostrophic (density) Currents
Grand Banks Turbidite
• Triggered by a magnitude 7.2 earthquake• Snapped 12 transatlantic telegraph cables• Lines began snapping at 59 minutes and continued through 797
minutes• Velocity is estimated to be 20 m/sec• Flow thickness of several hundred meters• Minimum volume of175 cubic kilometers
Grand Banks Turbidite