English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The Escuminac Formation of-the Upper Devonian Miguasha Group at the western end of Chaleurs Bay, Quebec, famous for its fossil fish fauna, is a turbidite sequence whose environment of deposition has been a matter of debate. Interpretations vary with different authors between lacustrine or brackish to coastal marine. It is possibly of estuarine origin. Its total stratigraphic thickness of 117 m has been divided into eight lithostratigraphic units on the basis of vertical changes in sands tone: shale ratio. A lacustrine setting is feasible in view of the association with fluvial formations below (Fleurant Formation) and above (Bonaventure Formation), although these are separated by a disconformity or an angular unconformity from the Escuminac. The lack of any shelly marine invertebrate fauna is negative evidence indirectly favoring a lacustrine origin. Periodically stagnant bottom-water conditions evidenced by the preservation of laminites are compatible with a lake environment. The fossil fish fauna, however, contains elements which point toward brackish or marine environments. Geochemical evidence also seems to support brackish conditions, although it is not clear to what extent the geochemical signature may have been inherited from older marine detrital clays. A silled estuary would best accommodate the different lines of evidence, but poses problems of fitting into the broadscale paleogcographic picture of the Upper Devonian Old Red Continent.   RESUME  La Formation d'Escuminac du Groupe de Miguasha du Devonien superieur, dans la partie ouest de la baie des Chaleurs, Quebec, celebre pour sa faune de poissons fossile, est une sequence de turbidites dont l'environnement de deposition a fait l'objet de discussions. Les interpretations varient suivant les differents auteurs entre lacustre ou saumatre a marin cotier. C'est possiblement d'origine estuarienne. Son epaisseur totale de 117 m a ete divisee en huit unites lithostratigraphiques sur la base de variations verticales dans le rapport gres:shale. Un milieu lacustre est possible en regard de l’association avec les formations fluviatiles en-dessous (Formation de Fleurant) et au-dessus (Formation de Bonaventure), bien qu'elles soient separees de l’Escuminac par une inconformite ou une discordance angulaire. L'absence de toute faune marine invertebree a coquille est un argument negatif favorisant indirectement une origine lacustre. Des conditions d'eau de fond periodiquement stagnante, indiquees par la preservation de laminites, sont compatibles avec un environnement de lac. La faune de poissons fossile, cependant, contient des elements qui pointent vers des environnement saumatres ou marins. Les donnees geochimiques semblent aussi appuyer des conditions saumâtres, bien qu'il ne soit pas clair jusqu'a quel point la signature geochimique ait pu etre heritec d'argiles marines plus anciennes. Un estuaire endigue accomoderait le mieux les diverses donnees, mais rencontre des difficultes a s'incrire dans le cadre paleogeographique a grande echelle du continent Old Red du Devonien superieur.  [Traduit par la journal]

atlantic geology

Geology and sedimentology of the Upper Devonian Escuminac Formation, Qu&amp;#xE9;bec, and evaluation of its paleoenvironment: lacustrine versus estuarine turbidite sequence