The Campbellton Formation, New Brunswick, Canada: paleoenvironments in an important Early Devonian terrestrial locality

Abstract

Strata of the Campbellton Formation, nearly 1 km-thick and known for its diverse fossil assemblage of early plants, arthropods, and fish, can be divided into six facies associations: (1) restricted lacustrine, (2) marginal lacustrine, (3) near-shore lacustrine, (4) coastal-deltaic, (5) sandy to gravelly alluvial plain, and (6) gravelly proximal alluvial environments. Lacustrine deposits with restricted circulation, due to depth or stagnation, are fine-grained with preserved organic material. The marginal lacustrine association consists of massive siltstone and very fine sandstone, interbedded with conglomerate. The latter are interpreted to have shed from older volcanic units forming the basin walls. The near-shore lacustrine association is characterized by rippled sandstone with microbialites. Alluvial strata include interbedded imbricate to nonimbricate conglomerate, trough cross-stratified sandstone, and barren to plant-bearing siltstone. Rare exposures of thickly bedded imbricate to weakly imbricated cobble-boulder conglomerate with sandy plant-bearing lenses are interpreted as products of hyperconcentrated debris flows. In the western belt, a braided-fluvial system had paleocurrents flowing WNW. Coastal-deltaic deposits west of the fluvial outcrops, containing aquatic vertebrates and invertebrates, had paleocurrents flowing ESE, suggesting a confined body of fresh or brackish water. In lower parts of the eastern belt, lacustrine facies are prevalent, representing a large open lake. Alluvial facies dominate upper parts of the formation, representing an eastward-flowing axial braided river system, with proximal alluvium shed transversely from the basin margins. Although most strata have a volcanic provenance, only one outcrop in the lacustrine beds shows evidence of active volcanism during deposition of the Campbellton Formation.Résumé : D'une épaisseur d'environ 1 km, les strates de la Formation de Campbellton sont connues pour ses assemblages diversifiés de fossiles d'anciennes plantes, d'arthropodes et de poissons; elles peuvent être divisées en six associations de faciès : (1) lacustre restreinte, (2) lacustre de bordure, (3) lacustre près d'un rivage, (4) côtier-deltaïque, (5) plaine alluviale de sable à gravier et (6) environnements proximaux de gravier alluvionnaire. En raison de la profondeur ou de stagnation, les dépôts lacustres avec circulation réduite sont à grain fin et contiennent de la matière organique préservée. L'association lacustre de bordure comprend des siltstones massifs et des grès très fins, interlités avec des conglomérats. Ces derniers proviendraient d'anciennes unités volcaniques qui forment les parois du bassin. L'association près du rivage est caractérisée par des grès ridés contenant des microbialites. Les strates alluvionnaires comprennent un conglomérat imbriqué à non imbriqué, des grès de fosse à stratification croisée et des siltstones stériles à contenant des plantes. De rares affleurements de conglomérats imbriqués à lits épais à des conglomérats de cailloux à blocs faiblem...

A eurypterid from the lacustrine facies of the Early Devonian Campbellton Formation, New Brunswick, Canada

“…The paleoenvironment for the specimen described herein, in a marginal lacustrine facies, is consistent with the setting described for Parahughmilleria from other Early Devonian sites. The two outcrop belts of the Campbellton Formation that have yielded eurypterids were interpreted as having been deposited in western and eastern sub-basins by Kennedy and Gibling (2011), possibly separated by a topographic barrier. In both sub-basins, sparse eurypterid material has been found at low stratigraphic levels in the formation, within a few tens of metres of the basal contact with the Val d' Amour those specimens possess only a rounded semi-lunar sculpture, suggesting that the specimen described here as cf.…”

“…Repeated searches have uncovered no additional material. The eurypterid bed occurs at a level 14 m above the base of section III in the marginal lacustrine facies association described by Kennedy and Gibling (2011). The outcrop consists of thick beds of horizontally stratified granule-pebble conglomerate, sharply overlain by massive to graded beds of grey siltstone.…”

“…These beds were described as representing a mix of wetland, alluvial-plain and lacustrine environments (Kennedy and Gibling 2011) and, in addition to plants, have yielded the oldest land animal assemblage in North America, including scorpion and arthropleurid fossils (Shear et al 1996) and millipede fossils (Wilson 2006). A single abdominal eurypterid fragment was found in these beds in 1997, just east of Point La Nim, from a hard, grey siltstone unit approximately 1.6 m from beach level (Fig.…”

The classic Lower Devonian plant-bearing deposits of northern New Brunswick, eastern Canada: Dispersed spore taxonomy and biostratigraphy

“…However, placing the plants in a secure stratigraphical context has been hampered because the stratigraphy of the deposits was unclear and they were poorly age-constrained. Recent work on the stratigraphy, sedimentology and palaeoecology of the deposits (Kennedy and Gibling, 2011;Kennedy et al, 2012aKennedy et al, ,b, 2013, coupled with analysis of their dispersed spore/pollen assemblages (this work), now enables these plant communities to be considered within a rigid stratigraphical/biostratigraphical framework.…”

Dental patterning in the earliest sharks: Implications for tooth evolution

“…Herein, we describe the almost intact battery of oral teeth from Doliodus problematicus (Fig. ; NBMG 10127, Lower Devonian, New Brunswick, Canada, 397 Ma; Kennedy and Gibling, ), the oldest known tooth‐bearing shark with a relatively intact oral dentition (Miller et al, ; Turner, ). Tomographic scanning and segmentation analysis (or “digital preparation,” whereby structures are extracted virtually from surrounding rock) of NBMG 10127 provided a means to investigate and reconstruct its dentition (Fig.…”