--> Abstract: Ichnological Patterns at Kouchibouguac Estuary, NB, Canada; #90063 (2007)

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Ichnological Patterns at Kouchibouguac Estuary, NB, Canada

 

Hauck, Tyler E.1, Murray K. Gingras1, S. George Pemberton1 (1) University of Alberta, Edmonton, AB

 

A modern microtidal barrier island / embayment system in New Brunswick, Canada was studied to describe its ichnological characteristics for integration into existing bay / estuary facies models. The main dataset comprised soft-sediment cores taken from depositional sub-environments throughout the bay. Cores were x-rayed to facilitate description and interpretation of the burrows present and to estimate relative abundance. In addition to the cored data, burrow-diameters and trace diversities were recorded throughout the bay (at fixed stations). Sediment was collected from each station for analysis of both textures and total organic carbon contents.

 

We found that the shallow lagoon is heavily bioturbated by a depauperate assemblage of benthic organisms: the animal activities obscure or eradicate most primary physical sedimentary structures. Gradually and up to the fluvial-marine transition the preservation of physical sedimentary structures is more prevalent. Other trends that are noted up-estuary are: (1) the mean diameter of burrows is smaller in two species of polychaete; and, (2) the diversity of benthic organisms decreases gradually in a landward direction. Contour maps produced from the various measurements of burrow diameter are used to illustrate the trends in dimunition and diversity of tracemaking organisms up estuary. The map shows a gradual decrease in the size-diversity index (burrow diameter x diversity of burrows locally) up the fluvial-marine transition, and in general a lower size-diversity index is evident closer to tidal channels and shorelines. In most respects our efforts at Kouchibouguac support previous articulations of the brackish-water model. However, they also aptly demonstrate the potential for high-resolution paleogeographic studies using ichnofossil measurements to estimate relative salinities and reveal discrete depositional locales.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California