Trace fossils in a Lower Palaeozoic submarine canyon sequence-the Siegas Formation of northwestern New Brunswick, Canada

The Siegas Formation (Silurian - early Llandovery) of northwestern New Brunswick represents, in part, an ancient example of a submarine canyon sequence, erosive into and partially coeval with the Carys Mills Formation of late Ordovician—middle Llandovery age. The canyon succession contains a moderately diverse ichnofauna consisting of Buthotrephis, Chondrites, Cochlichnus anguineus, Diplichnites, Fucusopeis, Gordia arauata, Gordia, Gyrochorte, Helminthoida labyrinthica, Helminthopsis of. abeli, Neonereites bieerialis, Neonereites unieerialis, Planolites beverleyensis, Protopaleodictyon, Scalarituba missourieneis and Skolithos. These trace fossils are described in detail. Contrary to previous predictions that dwelling burrows and associated traces would predominate in submarine canyon sequences, the Siegas Formation contains traces produced essentially by vagile sediment eaters. This Is perhaps best explained by the absence within the canyon, at least for the majority of time, of sufficiently strong bottom currents, which precluded inhabitation by an active and abundant suspension feeding population. Instead, the sediments probably contained sufficiently abundant organic detritus to support an active population of infaunal sediment feeding organisms