Marine Clastic Shelf Facies
Types of Shelves
a. tidal-dominated (17%)
diurnal - 2 high, 2 low - Bay of Fundy, Nova Scotia
semidiurnal - 1 high, 1 low, Gulf of Mexico
mixed tides - California coast Pacific Ocean
tidal bulge - sun/moon gravitational attraction, rotates around
amphidromic
sediments and structures = Fig. 12.8, p. 430
b. storm-dominated shelves (80%)
fair weather wave base = 10 to 15 m
storm wave base = as much as 200 m
wind-forced currents with Coriolis deflections
onshore = coastal setup
offshore = geostrophic or longshore current
sediments and structures = tempestites with hummocky Xstratification
c. ocean current shelves (3%)
density currents - due to changes in salinity, temperature or
suspension
nepheloid layer
sediments and structures = mostly relict sediments
3. Finish Clastic Marine Facies Models
Hummocky cross stratification
Glauconitic sands
Deep Sea Facies