Abstract

Identification of salt-marsh deposits in the rock record can aid in the paleoenvironmental reconstructions of ancient marginal-marine successions. Salt-marsh sediments exposed at Waterside Beach and in Waterside Marsh alongside the Bay of Fundy, Canada offer an opportunity to describe and define facies and facies associations in a temperate, mineralogenic salt marsh. Three facies associations are identified and represent the three main components of the Waterside Marsh–Beach depositional system. Facies Association (FA) 1 includes genetically related deposits that accumulate on the salt-marsh surface, FA2 comprises sediments deposited within the naturally formed tidal creeks, and FA3 encompasses sediments derived from the adjacent coarse-grained beach. Facies Associations 1 to 3 respectively comprise 3, 4, and 2 sedimentologically and ichnologically distinct facies.

Application of these facies and facies associations to the rock record is dependent upon the preservation potential of the facies and the relative sea level (RSL) regime of the system. RSL in the Bay of Fundy is presently rising. This results in transgression of Waterside Beach and erosion of the upper 4 to 5 m of salt-marsh sediment at the beach-marsh interface. Consequently, the probability of sediments being preserved increases with distance from the seaward limit of the marsh and with depth. Sediments deposited on the salt-marsh surface well away from the seaward edge of the marsh (FA1) and those deposited at the base of the tidal creeks (FA2) have a high probability of being preserved. Conversely, the coarse-grained clastic sediments of FA3 deposited near the seaward edge of the marsh will likely be eroded.