PRESERVATION POTENTIAL OF SALT-MARSH FORAMINIFERA FROM THE FRASER-RIVER DELTA, BRITISH-COLUMBIA

Three biofacies were recognized in samples collected at a depth of 10cm along three transects from the marshes of the Fraser River delta, British Columbia. These biofacies, defined by comparison with those previously identified from surface marsh samples, correspond to three elevational zones: the High Marsh Zone, characterized by the Jadammina macrescens biofacies; the Lower High Marsh Zone, characterized by the Ammonia beccarii biofacies; and the Low Marsh Zone, characterized by the Miliammina fusca biofacies. A dramatic decrease in the abundance of Ammonia beccarii at 10cm depth suggests that the calcareous tests of this species are poorly preserved in the low pH subsurface sediments. As a result, the Ammonia beccarii biofacies will no longer be recognizable after extended burial. Although fewer biofacies can be resolved from paleomarshes of the Fraser delta than at the surface, it is still possible to differentiate between a High Marsh fauna (>+0.94m above mean sea level) and a Low Marsh fauna (<+0.94m above mean sea level).