Sixty-six suites of trace fossils from thirty-four different localities were collected or observed in the Carboniferous Mabou and Cumberland groups of western Cape Breton Island. Recurrent suites have been compiled into thirteen ichnocoenoses. Twelve of these ichnocoenoses, together with others from the Carboniferous elsewhere in the Maritimes, can be considered representative of two revised ichnofacies and their related composite ichnofacies. The remaining ichnocoenosis is currently anomalous. In our view, some ichnofacies identifi ed in the nonmarine realm have been too broadly defi ned. They allow for the inclusion of ichnocoenoses that are better considered representatives of composite ichnofacies. The Mermia ichnofacies is thus emended to consist primarily of systematic-coverage interface burrows and trails, irregular interface burrows and trails, non-striate pits, sinusoidal burrows and trails, migrating burrows, systematic-coverage burrow networks, (dense coverage) simple burrows and, if present, subordinate trackways. It remains an ichnofacies indicative of quiet water, oxygenated, permanently subaqueous conditions with signifi cant organic input. Two Cape Breton Island ichnocoenoses are representative of the revised Mermia ichnofacies. The Scoyenia ichnofacies is emended to consist primarily of bilobate or striate pits and trails, trackways, meniscate burrows, (sparse coverage) simple burrows and, if present, subordinate vertical burrows. It remains an ichnofacies indicative of transitional environments, specifi cally quiet water conditions that regularly dry out, or periodically inundated fl oodplains. Four Cape Breton Island ichnocoenoses are representative of the revised Scoyenia ichnofacies. Six ichnocoenoses from Cape Breton Island contain some trace fossils considered typical of both the Mermia and Scoyenia ichnofacies as emended. Two interpretations are possible. These ichnocoenoses might indicate instances where the trace-fossil producers were environmentally tolerant animals that could inhabit and behave similarly in either setting. Alternatively, they may represent cases where producers active in different environments had their traces juxtaposed or even overprinted due to a change in environmental conditions. In this latter case, the ichnocoenoses can be considered examples of composite ichnofacies that are taphonomic successors of combinations of the Mermia, Scoyenia, and the well-established Skolithos ichnofacies. RÉSUMÉ Soixante-six ensembles d'ichnofossiles de 34 emplacements différents ont été prélevés ou observés dans les groupes carbonifères de Mabou et de Cumberland dans l'ouest de l'île du Cap-Breton. Les ensembles répétitifs ont été compilés au sein de 13 ichnocoenoses. Douze de ces ichnocoenoses, auxquelles on peut ajouter les autres exemplaires du Carbonifère présents ailleurs dans les Maritimes, peuvent être considérées comme des types représentatifs de deux ichnofaciès révisés et de leurs ichnofaciès composites connexes. Les autres ichnocoenoses constituent actuellement des types...
Carboniferous (Namurian-Westphalian A) strata of the Mabou and Cumberland groups outcrop extensively in western Cape Breton Island. As well as a diverse collection of burrows, trails, pits, and coprolites described previ ously, numerous surface marks, mostly trackways, were encountered in these strata: Diplichnites cf. logananus (Marsh) Smith, Appendage Marks (types A and B), an "Arthropod Resting" Trace, Horn-shaped Surface Traces, and Vertebrate Trackways (types A, B, C, D, E, and F).Des strates du Carbonif&re (Namurien-Westphalien A) des groupes de Mabou et de Cumberland aifleurent sur une surface dtendue dans l'ouest de l 'ile du Cap-Breton. On rel&ve en outre dans ces strates une collection diversifide de terriers, de pistes, de trous et de coprolites ddcrits antdrieurement; un grand nombre de marques au sol, en majeure partie des pistes, comme celles du Diplichnites cf. logananus (Marsh) [Traduit par la rddaction] I n t r o d u c t io nThis paper describes and discusses several o f the trace fossils encountered at various localities in western Cape Breton Island (Fig. 1). The numerous surface markings described (pri marily trades and trackways) occur in Carboniferous (Namurian-W estphalian A) M abou and Cumberland Group strata that have been confidently inferred to be the products of fluvial, floodplain, and lacustrine sedimentation in half grabens main tained by a transtensional tectonic regime (Keighley and Pickerill, 1996a). The surface markings may occur exclusive of, or asso ciated with, the trace fossils already described from these strata by Keighley and Pickerill (1997); Baird (personal com munication, 1989Baird (personal com munication, ,1994 and his co-workers have collected additional material that remains undescribed. Future work will assess the palaeoenvironmental distribution of our specimens.N o m e n c l a t u r a l p r o b l e m s and t e r m in o l o g y Before presenting our taxonomic classification o f the trace fossils from the study area, it is necessary to first comment on the chaotic taxonomic nom enclature that exists for both •Current Address: Department of Earth Sciences, University of Liverpool, Brownlow Street, Liverpool, England, L69 3BX vertebrate and invertebrate trackways and explain the prin ciples behind our nomenclatural decisions. As stated in Keighley and Pickerill (1996b, 1997) and Pickerill and Keighley (1997), an ichnotaxon can only be formally nam ed (and hence diag nosed) from distinguishing morphological features, follow ing the guidelines o f the International Code o f Zoological Nomenclature (I.C.Z.N., 1985). Criteria such as (a) the phy togeny of the producer, (b) stratigraphic limitation of the trace fossil, or (c) the environm ent in which the trace fossil was produced, are not criteria that can be directly, or objectively, observed or proven in a type specimen. Therefore they re main hypothetical concepts and so cannot be used to pro vide a name based upon the 'Principle o f the Name-bearing Type' (I.C.Z.N., 1985, p. xiii, Article lb-1). Specificall...
Strata of the Mabou and Cumberland groups (Namurian-Westphalian A) outcrop extensively in western Cape Breton Island. Trace fossils were encountered at various localities, and include: Circulichnus montanus (nom. correct.), Cochlichnus anguineus, Cochlichnus isp., Conichnus isp., Cruziana problematica, Didymaulichnus cf. lyelli, Diplopodichnus biformis, Gordia marina, Helminthopsis abeli, Helminthopsis hieroglyphica, Palaeophycus striatus, cf. Palaeophycus,Phycodespedum, Planolites beverleyensis,Planolites terraenovae, cf. Planolites, Rusophycus carbonarius, cf. Rusophycus, Selenichnites isp., Taenidium barretti, cf. Taenidium, Thalassinoides suevicus, Undichnus binus (nom. correct.), Undichnus consulcus (nom. correct.), cf. Undichnus, coprolites, interface trails (types A, B, and C), plug-shaped burrows, small ovate pits (types A, B, and C), and vertical 'escape' structures. In total (including tracks and trackways not described herein), twenty-two ichnogenera have been identified that comprise a total of eighteen named ichnospecies, eight ichnospecies retained in open nomenclature, and thirteen unnamed ichnospecies. A further ten trace-fossil morphologies (comprising twenty different types) are retained in the ver nacular.On trouve de vastes affleurements de strates des groupes de Mabou et de Cumberland (Namurien -Westphalien A) dans l'ouest de Tile du Cap-Breton. On y a releve des ichnofossiles en divers endroits, notamment: le Circulichnus montanus (nom corrige), le Cochlichnus anguineus, le Cochlichnus isp., le Conichnus isp., le Cruziana problematica, le Didymaulichnus cf. lyelli, le Diplopodichnus biformis, le Gordia marina, le Helminthopsis abeli, le Helminthopsis hieroglyphica, le Palaeophycus striatus, cf. le Palaeophycus, le Phycodes pedum, le Planolites beverleyensis, le Planolites terraenovae, cf. le Planolites, le Rusophycus carbonarius, cf. le Rusophycus, le Selenichnites isp., le Taenidium barretti, cf. le Taenidium, le Thalassinoides suevicus, VUndichnus binus (nom corrige), VUndichnus consulcus (nom corrige), cf. P Undichnus, des coprolites, des pistes de reptation de jonction (types A, B et C), des trous de forme cylindrique, de petites fossettes ovees (types A, B et C) et des structures de " fuite " verticales. On a releve au total (et ce, y compris des traces et des traces non decrits aux presentes) 22 ichnogenres comprenant 18 ichnoesp&ces nominees, huit ichnoespeces retenues dans une nomenclature ouverte et 13 ichnoespeces sans nom. On retient en plus les noms vulgaires de dix autres formes d'ichnofossiles (qui comprennent 20 types differents). Morphological terminology is not covered by the I.C.Z.N. and, unfortunately, such term inology frequently has differ ent definitions attached to it, potentially causing nomenclatural confusion. For clarity, therefore, it should be noted that our use o f 'burrow', 'w all', 'lin in g', 'm eniscus', and 'branching' follow s K eighley and Pickerill (1 9 9 4 ,1 9 9 5 ). A 'm ould' is a 'negative' o f the original structure and a 'cast' is a reproduction ...
The Albert Formation (Horton Group) of the Moncton Basin, New Brunswick, is host to the only onshore petroleum system in the Maritime Provinces from which oil and natural gas are commercially produced. Production from the McCully gas field is from tight reservoir sandstone in the upper part of the Albert Formation. An outcrop analogue is herein identified on the basis of a comparison of subsurface and surface gamma ray logs. The analogue is exposed in four roadcuts 15 km to the west of the field, between Sussex and Norton. The succession in the roadcuts is about 60 m thick and can be divided into three, roughly 20 m thick units: a lower interbedded grey mudstone and sandstone interval, a medial organic rich grey mudstone interval, and an upper interbedded grey sandstone and mudstone interval. The lower interval is interpreted as having been deposited in a lacustrine offshore transition and lower shoreface setting. The overlying medial interval is interpreted as offshore, with the upper interval assigned to a lacustrine shoreface and shoreline (with some fluvial, possibly deltaic influence). The lower and upper interbedded sandstone intervals are viewed as progradational sediment packages deposited during times of stable lake level whereas the intervening mudstone-dominated medial interval represents a period of renewed lake deepening. On a larger scale, the entire succession is considered part of the final progradation of an axial fluvio-deltaic system into the Albert lake. RÉSUMÉLa formation Albert (Groupe Horton) du bassin de Moncton, Nouveau Brunswick, abrite le seul système pétrolier terrestre dans les Provinces Maritimes à partir duquel le pétrole et le gaz naturel sont exploités commercialement. La production de gaz naturel du champ de McCully provient d'un réservoir de grès peu perméable, situé dans la partie supérieure de la formation Albert. L'affleurement analogique ci-inclus est identifié sur la base d'une comparaison de diagraphies de rayons gamma souterrains et en surface. L'analogue est exposé dans quatre affleurements sur le bord de la route à 15 km à l'Ouest du champ, entre Sussex et Norton. Dans ces affleurements, la succession indique une épaisseur d'environ 60 m, et peut être divisée en trois unités d'une épaisseur approximative de 20 m: un intervalle inférieur intercalé de mudstone gris et de grès, un intervalle médian de mudstone gris riche en matières organiques, et un intervalle supérieur intercalé de grès et de mudstone gris. L'intervalle inférieur est interprété comme ayant été déposé au cours d'une transition de dépôt lacustre hauturier et d'une sédimentation inférieure d'avant-côtes. L'intervalle médian sus-jacent est interprété comme étant hauturier, avec l'intervalle supérieur affecté à un dépôt lacustre d'avant-côtes et littoral (avec quelques influences fluviales, possiblement deltaïques). Les intervalles intercalés de grès inférieurs et supérieurs sont considérés comme étant des sédiments compacts progradants, déposés durant les époques de niveaux stables du lac, alors que l'appari...
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