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The Norumbega Fault system is traced from southern New England to Prince Edward Island, and its major strike-slip history is pre-Carboniferous. Carboniferous and later movements are less well constrained. Along the Fredericton Fault in western New Brunswick, offsets affect outcrops of Carboniferous strata in several ways. Revision of Carboniferous stratigraphy in this area using new miospore data and mapping of new exposures augmented by LiDAR imagery permits refinement of some of the post-Devonian movement history. The oldest post-Silurian unit recognized, the Longs Creek Formation, is fault-dissected and tightly folded, with faults and folds overlapped by the unconformity at the base of the upper Visean Shin Formation. The age of the Longs Creek Formation is uncertain and may be late Devonian to early Visean. Faults affecting the Shin Formation and Royal Road basalts are truncated by the unconformity at the base of the Bolsovian Minto Formation. Beneath this unconformity the presence of fault-bounded panels of vertical Langsettian strata (Boss Point and Deerwood formations) along the Fredericton Fault demonstrate late Visean to Serpukhovian, and post-Langsettian, pre-Bolsovian (Duckmantian) movements. At least three phases of movement can be seen affecting the Minto Formation. All the movement phases along the Fredericton Fault appear to be right-lateral strike-slip, except for one phase of post-Bolsovian left-lateral displacement. [ABSTRACT FROM AUTHOR]

The role of tectonism associated with right lateral strike- slip faults, and related salt movement is well-documented along the eastern part of Fundy coast of New Brunswick and adjacent parts of Nova Scotia. They relate to the Yeadonian-Langsettian (early Pennsylvanian) evolution of the Cumberland basin. Transpressional flower structures of similar age are seen from the Saint John area west to Lepreau. More recent structural mapping and related stratigraphic research between Saint John and Alma has defined more transpressional flower structures affecting lower Pennsylvanian strata, and transtensional structures involved in lower Pennsylvanian deposition (Tynemouth Creek Formation), and Permian-Triassic sequences from Quaco Head, Martin Head, and Waterside. Some of these structures involved salt movement, with candidates for salt welds and diapirs now identified from Quaco Head, Martin Head, Waterside, and Alma. Timing remains an issue, but early-middle Pennsylvanian salt movement is most probable around Alma and Waterside (comparable and contiguous with structures seen on the Maringouin Peninsula and at Joggins), while the gypsum (and salt?) diapir at Martin Head could be as young as Triassic (depending on the age of the hanging wall rocks (currently correlated with middle-upper Triassic formations around St. Martins, viz: Echo Cove Formation). Refinement of the Permian and Triassic stratigraphy is underway and will further help to elucidate a detailed tectonic history, but the persistence of the right lateral strike-slip regime from the early Pennsylvanian through the Permian into the lower to middle Triassic seems probable. This begs the question of when the post-Alleghenian adjustments related to major orogen-parallel faults gave way to regional extension associated with opening of the mid-Atlantic ocean basin. With which regime should the half-grabens of the Fundy Basin (and its continuation to the southwest to the Hartford and Newark basins) be considered related? [ABSTRACT FROM AUTHOR]

The Partridge Island block is a newly identified tectonic element in the Saint John area of southern New Brunswick, located south of and in faulted contact with Proterozoic and Cambrian rocks of the Ganderian Brookville and Avalonian Caledonia terranes. It includes the Lorneville Group and Tiner Point complex. The Lorneville Group consists of interbedded volcanic and sedimentary rocks, subdivided into the Taylors Island Formation west of Saint John Harbour and West Beach Formation east of Saint John Harbour. A sample from thin rhyolite layers interbedded with basaltic flows of the Taylors Island Formation at Sheldon Point yielded a Late Devonian - Early Carboniferous U-Pb (zircon) age of 358.9 +6/-5 Ma. Petrological similarities indicate that all of the basaltic rocks of the Taylors Island and West Beach formations are of similar age and formed in a continental within-plate tectonic setting. West of Saint John Harbour, basaltic and sedimentary rocks of the Taylors Island Formation are increasingly deformed and mylonitic to the south, and in part tectonically interlayered with mylonitic granitoid rocks and minor metasedimentary rocks of the Tiner Point complex. Based on magnetic signatures, the deformed rocks of the Tiner Point complex can be traced through Partridge Island to the eastern side of Saint John Harbour, where together with the West Beach Formation, they occupy a thrust sheet above a redbed sequence of the mid-Carboniferous Balls Lake Formation. The Tiner Point complex includes leucotonalite and aegirine-bearing alkali-feldspar granite with A-type chemical affinity and Early Carboniferous U-Pb (zircon) ages of 353.6 ± 5.7 and 346.4 ± 0.7 Ma, respectively. Based on similarities in age, petrological characteristics, alteration, iron oxide - copper - gold (IOCG)-type mineralization, and deformation style, the Partridge Island block is correlated with Late Devonian - Early Carboniferous volcanic-sedimentary-plutonic rocks of the Cobequid Highlands in northern mainland Nova Scotia. Deformation was likely a result of dextral transpression along the Cobequid-Chedabucto fault zone during juxtaposition of the Meguma terrane. [ABSTRACT FROM AUTHOR]

The Weldon Formation of the Lower Carboniferous (Tournaisian) Sussex Group of southeastern New Brunswick consists of red mudstone intervals interbedded with red siltstone and fine-grained sandstone. Some of the mudstone intervals excemudstoneed 50 m in thickness and are deformed in such a way as to render bedding ambiguous. At two localities south of Moncton, these thick mudstone intervals carry two fracture cleavages that are almost perpendicular to each other, and perpendicular to bedding. In the Weldon Creek section these cleavages are particularly well preserved, and a clear timing relationship can be established. The second cleavage crenulates and transposes the first, which typically carries a slicken lineation where lithons are deformed by crenulation. Thin section and scanning electron microscope images reveal that these cleavages are defined by microveins of calcite, gypsum, and montmorillonitic clays with hematite and vivianite, and that there is some evidence for silica dissolution. At Belliveau Village, these two cleavages are largely disrupted by layer-parallel shear planes in the limb of the Belliveau syncline, indicating that they predated folding. The presence of primary diagenetic gypsum, primary carbonate cement in interbedded sandstone, and low equivalent vitrinite reflectance (%R) values in underlying oil shale (0.65-0.77) indicate that these cleavages formed below 100 °C during diagenesis rather than under anchizone conditions. Their presence reflects a bulk shortening parallel to bedding prior to fold development, and layer-parallel deformation during folding progressively destroyed them. These early cleavages are not precursors to slaty cleavage, and are essentially ephemeral features, though they could provide another anisotropy on which later cleavages might nucleate. [ABSTRACT FROM AUTHOR]

A major ductile high-strain zone up to 5 km in width can be traced for at least 70 km diagonally across the Avalonian Caledonia terrane of southern New Brunswick. A study of the northeastern part of this zone from the Prosser Mountain area in the northwest to the Point Wolfe River area west of Fundy National Park shows that both the ca. 630-620 Ma Broad River Group and associated plutons and the 560-550 Ma Coldbrook Group contain similar structural elements, related to a largely shared deformational history. Some of this history is apparent also in the 560-550 Ma plutonic rocks. A pervasive foliation (S1) lies parallel to bedding (S0), and although evidently composite (S0-1) in the Broad River Group, this fabric is very heterogeneous in the younger Coldbrook Group, where low strain enclaves are widespread. No folds have been seen of an F1 generation, and no reversals of facing or vergence are apparent. A mineral lineation (Lm¹) is locally prominent, defined by biotite aggregates. The plutonic rocks have fabrics that developed during and soon after crystallization, including a foliation (S1) producing augen-gneiss with a prominent L-tectonite (Lm¹). S1 in the plutonic rocks also includes a schistosity associated with the growth of white mica and breakdown of feldspar. Geometry suggests that S1 in the granites is related to S0-1 in the supracrustal rocks, and the mineral lineation (Lm¹) in both units shares a common orientation. S1 and S0-1 are crenulated by a strong second cleavage (S2) axial planar to folds (F2), the large-scale expression of which is an asymmetric synform containing a belt of Coldbrook Group rocks. Kinematic indicators for F2 structures suggest an overall top-to-the-southeast motion along thrusts that stack units of Broad River Group, Coldbrook Group, and plutonic rocks. Fabric development in the older plutonic rocks implies a history of exhumation beginning under hot, anhydrous conditions during and soon after crystallization at ca. 620 Ma, followed by hydration during retrogression as plutonic rocks were tectonically emplaced into this crustal stack. The age of the later tectonic events is not yet well constrained, but could be as late as Carboniferous. [ABSTRACT FROM AUTHOR]

A new specimen of Batrachichnus salamandroides was recovered from a recently discovered fossil-bearing site situated along the southern shore of Grand Lake, New Brunswick, among a diverse ichnofaunal assemblage from the Middle Pennsylvanian (upper Bolsovian; lower Moscovian), upper Minto Formation. The identity of the tracemaker of this ichnogenus is reinterpreted as a composite of various late Paleozoic tetrapod taxa, based on similarities of the postcranial skeletons, notably that of the manus and pes, of both temnospondyls and some “microsaurs”. These results indicate that the tracemaker of the monospecific ichnogenus Batrachnichus is not limited solely to a temnospondyl tracemaker, as previously interpreted, and that some “microsaurs” should also be considered among tracemaker candidates for this ichnotaxon. [ABSTRACT FROM AUTHOR]

The evolution of arborescence in Devonian plants, followed by their architectural radiation in the Carboniferous, is a transition fundamental to Earth-system processes and ecological development. However, this evolutionary transition in trees is based on preserved trunks, of which only a few known specimens possess crowns. We describe Mississippian-aged (Tournaisian) trees with a unique three-dimensional crown morphology from New Brunswick, Canada. The trees were preserved by earthquake-induced, catastrophic burial of lake-margin vegetation. The tree architecture consists of an unbranched, 16-cm-diameter trunk with compound leaves arranged in spirals of ∼13 and compressed into ∼14 cm of vertical trunk length. Compound leaves in the upper ∼0.75 m of the trunk measure >1.75 m in length and preserve alternately arranged secondary laterals beginning at 0.5 m from the trunk; the area below the trunk bears only persistent leaf bases. The principal specimen lacks either apical or basal sections, although an apex is preserved in another. Apically, the leaves become less relaxed toward horizontal and are borne straight at an acute angle at the crown. The compact leaf organization and leaf length created a crown volume of >20–30 m3. This growth strategy likely maximized light interception and reduced resource competition from groundcover. From their growth morphology, canopy size, and volume, we propose that these fossils represent the earliest evidence of arborescent subcanopy-tiering. Moreover, although systematically unresolved, this specimen shows that Early Carboniferous vegetation was more complex than realized, signaling that it was a time of experimental, possibly transitional and varied, growth architectures. • Extensively preserved, ∼350 Ma trunk with protracted crown morphology • Early Carboniferous growth architecture presages modern fern lineages • Densely arrayed compound leaves provide expansive photosynthetic surface and cover • Fossils preserved as a consequence of earthquake-induced burial in ancient rift lake Newly discovered tree fossils from ∼350 Ma in New Brunswick, Canada, are architecturally unique, and Gastaldo et al. interpret them to presage modern tree-fern lineage growth forms. These fossils, preserved by earthquake-induced burial in an Early Carboniferous rift lake, may represent early evidence of a subcanopy forest niche. [ABSTRACT FROM AUTHOR]

New U-Pb zircon ages from volcanic, plutonic, and sedimentary units in the Avalonian Caledonia terrane of southern New Brunswick provide better timing constraints in this geologically complex area. Previous ca. 620 Ma ages from the Broad River Group are now corroborated by additional dates from felsic tuff in the Gordon Falls Formation and rhyolite in the former Fairfield (now East Branch Black River) Formation of 620 ± 5 Ma and 622 ± 1.9 Ma, respectively. Combined with ages ranging from ca. 625 Ma to 615 Ma from crosscutting plutons, the data suggest that the minimum age of the Broad River Group is about 615 Ma. A quartzfeldspar porphyry dyke in mafic volcanic rocks of the previously undated Long Beach Formation yielded an igneous crystallization age of 685 ± 10 Ma, the oldest unit yet dated in the Caledonia terrane but similar in age to porphyry in the Stirling belt in the Avalonian Mira terrane of Nova Scotia. The age of the Coldbrook Group was constrained previously by U-Pb (zircon) ages of volcanic rocks between 560 and 550 Ma as well as by similar ages from comagmatic plutons. Five additional samples from both volcanic and plutonic units lie in the same range of 560-550 Ma, including errors, demonstrating that the Coldbrook Group and related plutons formed in less than 10 million years. Such a large volume of mainly felsic magma erupted and emplaced in a short time span suggests a "supereruption/supervolcano" environment such as the late Cenozoic southwestern USA but not yet recognized at ca. 560-550 Ma elsewhere in Avalonia. Two units yielded Paleozoic ages: felsite of the Bloomsbury Mountain Formation with a zircon population at 427 ± 9 Ma, indicating a Silurian maximum emplacement age, and dacite of the Grassy Lake Formation with several zircon grains at 382.8 ± 8.3 Ma, indicating a maximum age of middle Devonian, the first rocks of this age to be identified in the Caledonia terrane. [ABSTRACT FROM AUTHOR]

The Early Mississippian (known as 'Romer's Gap') marks the beginning of a critical point in tetrapod history as they transitioned from dominantly aquatic to more terrestrial ecosystems. This paleoecological expansion set the stage for the radiation of all terrestrial tetrapod crown groups. The exact timing for the transition into freshwater continental environments is poorly understood. However, new discoveries in Scotland, England, and Nova Scotia, represent rare exceptions; offering a glimpse into coastal terrestrial ecologies during 'Romer's Gap'. These sites have evidence for a marine-water connection suggesting a coastal paleogeographic position. In contrast, Early Mississippian sedimentary deposits of the Moncton Subbasin in southern New Brunswick (NB) are interpreted as freshwater intra-continental conditions (lacustrine, wetland, fluvial, alluvial settings). A single stratigraphic horizon in the Albert Formation (Hiram Brook Member), exposed near Norton, NB, has yielded abundant tetrapod footprints. Preliminary assessments suggest at least four trackway ichnogenera: cf. Characichnos, cf.Matthewichnus, cf.Hylopus, and cf.Batrachichnus and a fifth trackway that may represent a new ichnogenus. Footprints range in size from 1 to 3 cm, suggesting that tetrapods were smaller than those documented from near time-equivalent sites in Nova Scotia, but are comparable in size to skeletal fossils described from younger strata in Scotland. These footprints are interpreted to be preserved in interfluvial crevasse splays associated with wetland forests dominated by Lepidodendropsis lycopods and Aneimites ferns preserved in their ecological context. The relatively large sample size of footprints suggests that a community of tetrapods were present and part of a diverse ecosystem, adapted to terrestrial and semi-aquatic continental environments in the earliest Mississippian. Additional trackways from slightly younger redbed playa lake deposits in the Sussex Group suggest tetrapods were also venturing into semi-arid continental environments. The ichnofossil assemblage from NB demonstrates considerable variation in ichnotaxa morphology and paleoenvironmental context from sites of approximately equivalent age. [ABSTRACT FROM AUTHOR]