Facies Architecture and Ichnology of Recent Salt-Marsh Deposits: Waterside Marsh, New Brunswick, Canada

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 MarshBeach 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 beachmarsh 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.

An Ichnological and Sedimentological Facies Model for Muddy Point-Bar Deposits

“…The patchy distribution of these deposits, and their position within laminated and directly overlying the bioturbated units, suggest that sediment derived from the lower supratidal zone was brought into the channel by multiple processes. It is likely that periods of increased runoff (early spring), increased turbulence related to storms (late fall and winter), and winter ice rafting most contribute to the exotic detritus observed therein (Dalrymple et al 1991;Dashtgard and Gingras 2005).…”

Brackish-Water Ichnological Trends in a Microtidal Barrier Island-Embayment System, Kouchibouguac National Park, New Brunswick, Canada

“…Notably, previous studies aimed at understanding size-diversity-salinity relationships have concentrated on environments in which high tidal ranges (i.e., meso-to macrotidal regime, 2-4 m and .4 m respectively) expose large areas of intertidal sediment during low tides (Frey et al, 1987;Gingras et al, 1999;Dashtgard and Gingras, 2005;Dashtgard et al, 2006), or where tidal energy is the dominant force (e.g., Georgia coastal temperate subarctic with short cool summers and long cold winters (mean average precipitation 5 1058 mm, mean average temperature 5 4.9 uC). The lagoons and estuaries represent preglacial valleys drowned during Holocene transgression.…”

Onset of the glacioeustatic signal recording late Palaeozoic Gondwanan ice growth: New data from palaeotropical East Fife, Scotland

“…Macroform cross-bedding in many cases resembles Inclined Heterolithic Stratification (IHS), which Thomas et al (1987) argued is characteristic of lateral accretion on meandering reaches within the fluvial-tidal transition. Although not exclusive to such environments, IHS is now abundantly documented from the fluvial-tidal transition zone of modern systems (e.g., Dashtgard and Gingras, 2005;Sisulak and Dashtgard, 2012). The impoverished trace fossil suite is characteristic of highly stressed environments and wholly consistent with other examples of estuarine trace fossil suites (MacEachern and Gingras et al, 2011;Gingras and MacEachern, 2012).…”