Paleoflow data have been compiled for Late Carboniferous (late Westphalian A) to Early Permian alluvial deposits over a large area of Atlantic Canada. The data, which include more than 36 000 measurements of large-scale trough cross-strata, indicate a predominantly northeasterly paleoflow, and suggest that a major source area lay to the southwest of the region throughout the 30 Ma period represented. Uplands within the basin deflected paleoflow and probably formed important local drainage and sediment sources. Tectonostratigraphic analysis suggests that the drainage originated in the fold-and-thrust belt of the central Appalachians and parts of the northern Appalachians. Rivers probably followed northeast-oriented structural lineaments through the older Acadian mountains of the northern Appalachians. A considerable proportion of the rising orogen's drainage, and probably detritus, may have traversed basins along the strike of the mountain belt, a situation analogous to that of the modern Himalayas.
The Tynemouth Creek Formation (formerly the Tynemouth Creek and McCoy Head Formation) is redefined and detailed stratigraphic and structural sections through representative parts of the formation are presented. The Tynemouth Creek Formation is of Lower Pennsylvanian age and is at least 800 m thick. It is dominantly clastic, shows an overall upward-coarsening from siltstones and sandstones into conglomerates and was deposited in an alluvial fan and piedmont setting. Six sedimentary facies are recognized. (1) Coarse, polymict, clast-supported conglomerates dominate the upper part of the formation.(2) Tabular and channelized pebbly sandstones, up to 8 m thick represent braided channels, the former characterized by unstable banks and laterally migrating channels while the latter may have formed on the upper fan when periodic tectonic movement caused rejuvenation of the streams and resultant channel incision. (3) Erosive-based sandstones up to 30 m thick occur near the base of the formation and are interpreted as point-har deposits of large meandering rivers that existed on the floor of the basin beyond the alluvial fan toe. (4) Thin-bedded sandstones and siltstones were deposited on the banks and in abandoned channels of rivers which locally supported dense growths of CaZamiteA.(5) Red siltstones and sheet sandstones were laid down in interchannel and distal fan areas, the former by low-energy flooding and perhaps wind action; the latter by sheet floods. Paleosols and calcitic nodules are characteristic of this facies. (6) In areas starved of clastic sediment, shallow lakes occasionally formed and accumulated thin bioclastic (ostracode/gastropod/spirorbid) or algal limestones. Palaeocurrents are unimodal with a mean flow towards the north-west. The Tynemouth Creek Formation probably represents a sector of a large alluvial fan that built northward from the southern, fault-bounded margin of the Cumberland Basin. The upward-coarsening of the sequence may record continued tectonic rejuvenation of the source area, causing fan progradation and deposition of coarse, fan-head conglomerates over finer, lower fan sediments. A climate of alternating wet and (?hot) dry seasons is inferred from the sedimentary evidence as a whole. Un groupement unimodal des paleocourants est note, avec un vecteur moyen vers le nord-ouest. La formation de Tynemouth Creek correspond probablement a la portion d'un grand cone de dejection qui s'est edifie en direction nord, a partir de la bordure faillee du Bassin de Cumberland. La granulometrie croissante de la sequence correspond peut etre a un rajeunissement tectonique continuel de la region source, accompagne de la progression du cone ainsi que de la deposition de conglomerats grossiers du cone superieur sur les sediments plus fins de la partie inferieure du cone. Un climat marque par l'alternance entre saison humide et saison seche (chaude?) est deduit a partir des donnees sedimentologiques.
Remapping of the Quaco Head area of southern New Brunswick has revealed a more complex structure than had been previously documented. The structure is dominated by two major thrust faults that dip to the south and southeast at between 35 and 45°. The lower (younger?) thrust emplaces Precambrian basalts and tuffaceous siltstones (Coldbrook Group) over alluvial sediments of the Boss Point and Tynemouth Creek formations (Westphalian A–B). Resting unconformably on the upper surface of the basalt is a thin layer (≤ 10 m) of marine, basal Windsor Group limestone, disconformably overlain by alluvial conglomerates of inferred Hopewell Group age. This sequence is truncated by an older, southeast-dipping thrust fault, to the southeast of which lie Hopewell conglomerates overturned towards the west and northwest. The latter sequence probably forms the lower limb of a large recumbent fold. Folding and thrusting in the Quaco Head area may have begun during Westphalian B times, although major movement was probably post-Westphalian C and occurred contemporaneously with dextral strike-slip movement on the Minas geofracture. Following this Alleghenian–Variscan deformation, the area underwent deep erosion prior to the deposition of a thick sequence of Triassic alluvial sediments. The more southerly reverse fault was reactivated as a normal fault during a phase of late Triassic or Jurassic faulting along the Bay of Fundy that was probably related to early Atlantic rifting.
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