The Sedimentological and Ichnological Characteristics of the Mud-Dominated Fluvio-Tidal Deposits, The Petitcodiac River Estuary, NB, Canada

Alina Shchepetkina, Murray K. Gingras, and S. George Pemberton
University of Alberta, Department of Earth and Atmospheric Sciences Edmonton, Alberta, Canada
[email protected]

More sedimentological and ichnological research in the mud-dominated estuaries is necessary to better distinguish the rock-record expression of inner-estuary and fluvially-dominated deposits. Mud-dominated estuaries are under-represented in the literature since muddy locales are dangerous and difficult to work on. Another reason for the absence of studies on muddy environments is the obsolete concept that mud deposition is simple and unimportant.

The meandering 79 km Petitcodiac River Estuary is widely known as the Chocolate River due to the abundance of fine-grained material in the water. The river is located in the province of New Brunswick, Canada and debouches into the Bay of Fundy. The Petitcodiac River Estuary is characterized by the highest tides in the world and represents a well-mixed macrotidal estuary.

The detailed analysis of the mud-dominated point bars and tidal flats in the Petitcodiac River Estuary indicate that Inclined Heterolithic Stratification (IHS) is the dominant style of bedding. It consists of interlaminated silty and sandy mud. Low-angle, planar bedding and ebb-oriented current ripples predominate. IHS strata forming the point bars dips channelward. Tidal flats comprise 4-13 cm of liquid mud cover underlain by a firm substrate. Individual beds can be traced along the entire length of the point bar and are occasionally disturbed by large-scale slumping. Mud ripples, tool casts, erosional tongues, rip-up clasts, desiccation cracks, and sediment binding bacteria with patchy distribution have been observed on the tidal flat surface. All of these features have distinctive physical appearances that can be identified in rock-record examples.

AAPG Search and Discovery Article #90183©2013 AAPG Foundation 2013 Grants-in-Aid Projects