Lecture: Shelf to Pelagic Environments Clastic sediment depositional processes • Continental Shelf • Continental Slope/Rise • Deep Sea (Pelagic)
Neoproterozoic Storms
1
Clastic Shelf Settings – 5% Earth covered in water < 200m deep – Palimpsest Effect- reworking of relict sediments deposited at lower sea levels – Shelf sands - high porosity & permeability
2
Extent of the modern shelves
Epeiric seas: large bodies of shallow water. 75 Ma
3
Current Velocity/Grain Size Influence sedimentary structure and texture – Tidal Currents: a few to >100 cm/sec, all depths – Storms: Variable 10-100 cm/sec – Geostrophic Currents: 4 m) zones • strong tide currents (>100 cm/s) - sand ribbons or ridges – up to 40 m high – km wide & long – Low angle x-strata
