Estuary Environments Salmon River/Cobequid Estuary, Nova Scotia Landward limit of tidal facies Seaward limit of fluvial influence Estuary: a coastal embayment with mixed marine/fluvial influence Estuaries have retrogradational facies stacking pattern (form during transgression); deltas prograde and form during regression Tide-Dominated Estuary Flaser bedding, bidirectional (mostly seaward) x-beds, IHS Herringbone dune cross-bedding Wave-Dominated Estuary Wapengo Lagoon, Australia Central Basin Bay-Head Delta Flood-Tidal Delta Barrier Flaser bedding, bidirectional (mostly seaward) x-beds, IHS Fine-grained sed. Low-angle upper plane bed lamination Likely planar lamination, interfingering with central basin mud Flood-directed dunes (planar x-beds) High-energy tidal inlet (erosive base, 3D 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 Traces with sharp walls, scratch- marked walls, and/or contrasting sediment fill indicate firmground (firm but not lithified substrate) Skolithos and Arenicolites Rhizocorallium 1. Erosion of upper unconsolidated sediment exposes compacted firm lower layers Can occur at: tidal ravinement surfaces, wave ravinement surfaces, tidal channel lateral migration, tidal creek meanders (require exhumation of firm sediment in marine setting) 2. Organisms colonize firm substrate, creating open burrow networks 3. Subsequent deposition of contrasting sediment infills burrows FSST and LST missing, transgressive ravinement surface has scoured below maximum regressive surface and subaerial unconformity Combined TRS, MRS, RSME/SU Use name of most recent surface