Late Ordovician-Early Silurian trace fossils from the Matapedia Group, Tobique River, western New Brunswick, Canada. II. Additional discoveries with descriptions and comments
DOI :
https://doi.org/10.4138/1646Résumé
Previous recordings of Late Ordovician-Early Silurian flysch trace fossils (13 ichnogenera, 15 ichnospecies) from slope deposits of the Matapedia Basin at a single site on the Tobique River, western New Brunswick, are supplemented by the addition of 9 newly discovered ichnogenera (12 ichnospecies). These are:- Cirrculichnis montanus, Cruziana problematica, Cruziana cf. stromnessa, Dipt'tchnites ichnosp., Megagrapton irregulare, Monocraterion ichnosp., Phycosiphon incertum, Rusophycus didymus, Rusophycus ichnosp. types A and H, Scolicia ichnosp, and Tuberculichnus ichnosp. The traces are poorly preserved and occur only in low numbers compared to previously documented forms. Nevertheless, the meticulous sampling procedures adopted at the site emphasize the need for detailed collecting, before drawing conclusions regarding diversity models, stratigraphic distribution, etc., of trace fossils. Of these new forms only Diplichnites ichnosp. has previously been recorded from die Matapedia Basin in the partially coeval Lower Silurian Siegas Formation. Tuberculichnus ichnosp. is recorded for the first time in North America. The combined total of 22 ichnogenera (27 ichnospecies) from the Tobique River represents the most diverse ichnocoenosis yet reported from a single ancient slope deposit. The occurrence of several more typically shallow-water ichnogenera (e.g., Cruziana, Diplichnites, Monocraterion and Rusophycus) suggests that, at least in the Early Palaeozoic, caution must be exercised in their utilization as distinctive facies or environmental indicators. RÉSUMÉ 9 nouveaux ichnogenres (12 ichnoespeces) s'ajoutent à ceux déjà répertoriés (13 ichnogenrcs, 15 ichnoespcces) en un site unique localise sur la rivière Tobique, dans l’ouest du Nouveau-Brunswick, dans des sédiments tardiordoviciens è éosiluriens accumulés sur le talus continental du Bassin de Matapedia. Ce sont: Cirrculichnis montanus, Cruziana problematica, Cruziana cf. stromnessa, Dipt'tchnites ichnosp., Megagrapton irregulare, Monocraterion ichnosp., Phycosiphon incertum, Rusophycus didymus, Rusophycus ichnosp. types A et H, Scolicia ichnosp, et Tuberculichnus ichnosp. Ces demières sont malconservées et relativement rares par rapport aux formés déjà connues. Néanmoins, le dépouillement méiculeux utilisé à ce site démontre la nécessité d'une collecte détailiée avant de tirer des conclusions quant aux modeèles de diversité, à la distribution stratigraphique, etc., des traces fossiles. De ces nouvelles formés, seule Diplichinites ichnosp. est déjà cormue dans le Bassin de Matapedia, soil dans la Formation sihirienne inférieure et en partie synchrone de Siegas. On recense Tuberculichnus ichnosp. pour la première fois en Amerique du Nord. Le total combine de 22 ichnogenres (27 ichnoespeces) présents sur la rivière Tobique représente l’inchnocoenose la plus diverse jamais répertoriée dans un seul dépôt de talus. La présence de plusieur sichnogenres typiques d'une faible tranche d'eau (e.g., Cruziana, Diplichnites, Monocraterion et Rusophycus) démontre que la prudence est de mise lors de leur utilisation à litre d'indicateurs de faciès on de milieu, tout particuliérement à l'Éopaléozoique. [Traduit par le journal]Téléchargements
Publié-e
1988-08-01
Comment citer
Pickerill, R. K., Fyffe, L. R., & Forbes, W. H. (1988). Late Ordovician-Early Silurian trace fossils from the Matapedia Group, Tobique River, western New Brunswick, Canada. II. Additional discoveries with descriptions and comments. Atlantic Geoscience, 24(2). https://doi.org/10.4138/1646
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