Estuary Environments Salmon RiverCobequid Estuary Nova Scotia Estuary

Estuary Environments Salmon River/Cobequid Estuary, Nova Scotia

Estuary: a coastal embayment with mixed marine/fluvial influence Estuaries have retrogradational facies stacking pattern (form during transgression); deltas prograde and form during regression Seaward limit of fluvial influence Landward limit of tidal facies

Tide-Dominated Estuary Herringbone dune cross-bedding Flaser bedding, bidirectional (mostly seaward) x-beds, IHS

Wave-Dominated Estuary Barrier Central Basin Bay-Head Delta Flood-Tidal Delta Wapengo Lagoon, Australia

Low-angle upper plane bed lamination Fine-grained sed. Flaser bedding, bidirectional (mostly seaward) x-beds, IHS

Likely planar lamination, interfingering with central basin mud

Flood-directed dunes (planar x-beds) High-energy tidal inlet (erosive base, 3 D dunes)

Transgressive Ravinement Surface: tidal or wave scour cut during landward transgression of shoreline Transgressive shoreface or estuary mouth deposits above; regressive fluvial or coastal below

Ravinement surfaces are stratigraphic discontinuities formed in a marine setting Can also be demarcated by distinctive trace fossils (animal burrows or borings) Glossifungites Ichnofacies Rhizocorallium Traces with sharp walls, scratchmarked walls, and/or contrasting sediment fill indicate firmground (firm but not lithified substrate) Skolithos and Arenicolites

1. Erosion of upper unconsolidated sediment exposes compacted firm lower layers 3. Subsequent deposition of contrasting sediment infills burrows 2. Organisms colonize firm substrate, creating open burrow networks Can occur at: tidal ravinement surfaces, wave ravinement surfaces, tidal channel lateral migration, tidal creek meanders (require exhumation of firm sediment in marine setting)

Combined TRS, MRS, RSME/SU Use name of most recent surface FSST and LST missing, transgressive ravinement surface has scoured below maximum regressive surface and subaerial unconformity