Maritimes Basin Research Articles

Late Devonian felsic magmatism in southern New Brunswick and its association with a large igneous province that may have contributed to the Frasnian-Famennian extinction

Felsic rocks of the Piskahegan Group and coeval plutons form a major part of a Late Paleozoic epicontinental caldera in southwestern New Brunswick, Canada. The caldera forms an elliptical structure with a length of ∼34 km and a width of ∼13 km. It hosts a significant polymetallic deposit of tin, molybdenum, indium and bismuth associated with mid-sequence granitic intrusions. The caldera formed in the aftermath of the late Early to Middle Devonian Acadian Orogeny during the opening of the late Paleozoic Maritimes Basin in the Northern Appalachian Belt. Its surrounding successions are largely composed of bimodal igneous rocks that were derived from two distinct sources: upper mantle-derived mafic magma and lower crust-derived felsic magma. The rocks that marked the beginning of volcanic activity in the caldera are no younger than 374.2 ± 2 Ma, whereas the uppermost dated volcanic unit in the complex yielded an age of 364.6 ± 0.7 Ma. The latter is conformably overlain by a succession of red beds and undated basalts that also overlie penecontemporaneous felsic volcanic rocks adjacent to the caldera. The post-orogenic felsic rocks are fractionated, peraluminous A-2 type rocks with silica contents ranging from ∼70 to ∼79 wt% along with high K2O contents and ɛNd(t) ranging from −0.10 to +1.05. They were generated by the melting of lower crustal basement rocks linked to a lithospheric plate that was metasomatized during the Neoproterozoic. Based on available geochemical, geophysical and structural data on Late Paleozoic rocks of southeastern Canada, the melting may have been triggered by the injection of profuse mafic magma that eventually formed a thick underplating at the base of the crust in association with heat derived from an underlying mantle plume and conveyed by transtensional structures. Basal rocks of the Piskahegan Group (the Intracaldera Sequence) and penecontemporaneous volcanic rocks in Nova Scotia are interpreted as small erosional remnants of a Large Igneous Province (LIP) based on the extensive exposure of large coeval plutons throughout southeastern Canada. The new geochronological data suggests that profuse late Frasnian magmatism in this LIP could have contributed to the environmental deterioration that led to a significant extinction at the Frasnian-Famennian boundary (the Kellwasser Event).

A primary evaporite weld revealed in the late Paleozoic Antigonish sub-basin of Nova Scotia

The Antigonish sub-basin lies within the late Paleozoic Maritimes Basin of Atlantic Canada. Late Devonian to early Carboniferous basin development resulted in a basin-and-range topography, within which the clastic Horton Group was deposited in grabens and half-grabens. The overlying Viséan Windsor Group contains substantial evaporite units; later basin development was accompanied by expulsion of these evaporites. In the Antigonish sub-basin, a significant stratigraphic omission surface initially described as a thrust was subsequently reinterpreted as the extensional Ainslie Detachment. This surface can be examined in drill-core, where the halite-bearing interval is reduced to 3.8 m of halite-cemented breccia of sedimentary rock fragments. The halite cement is sub-horizontally foliated and lineated. At Lakevale, an outcrop section of the Windsor Group is reduced in thickness to tens of metres. Above a basal limestone unit containing pseudomorphs of gypsum, most of the Windsor Group is represented by sedimentary-clast breccias that resemble those seen in core, but with the halite removed by solution in the near-surface environment. The stratigraphic record within the sub-basin implies that expulsion of lower Windsor salt was initially toward the edges of the basin where rising diapirs blocked the deposition of middle Windsor group, but in the basin centre a second salt unit was deposited. Subsequently, during contractional inversion of basin-bounding faults, the middle Windsor salt was expelled into diapirs near the centre of the basin. The Ainslie Detachment is reinterpreted as a primary salt weld: a boundary between units formerly above and below expelled lower Windsor evaporites. The resulting stratigraphic omissions and structures match those seen above expelled evaporite layers on continental margins.

Description of a tetrapod trackway from the early Carboniferous Bonaventure Formation of New Brunswick, Canada

The Bonaventure Formation is an early Carboniferous fossil-bearing rock unit that crops out in northern New Brunswick and eastern Quebec, eastern Canada. Here, we describe CMNFV 10013, a tetrapod trackway found in Bonaventure Formation outcrops on Heron Island, New Brunswick, by Robert Wheelock Ells in 1879. The specimen shows at least seven prints including two pes–manus couples, one of which is sufficiently well preserved to be attributable to Hylopus isp. Several underprints significantly depart from typical Hylopus tracks and emphasise the importance of considering taphonomy when identifying fossil trackways. CMNFV 10013 is the first described fossil reported from the Bonaventure Formation. It extends the Carboniferous Maritimes Basin tetrapod trackway record northwards and represents one of the oldest tetrapod trackways from Canada. Reviewing the global record of Hylopus isp. reveals CMNFV 10013 is also one of the earliest Hylopus found. This global record also reveals that Hylopus occurrences are clustered around the paleotropics, possibly suggesting a biogeographical preference. This specimen highlights the importance of describing forgotten museum specimens. Future research should focus on undescribed museum specimens and contributing to existing collections through fieldwork in the promising rocks of Heron Island.

Type material ofParaconularia planicostata(Dawson) from the Upper Mississippian of Nova Scotia, Atlantic Canada

Paraconularia planicostata(Dawson, 1868) is one of two species in this genus (Sinclair, 1940) of conulariid cnidarian currently known from Mississippian strata in the Maritimes Basin in Atlantic Canada (Babcock and Feldmann, 1986). A salient characteristic of the species is the presence of a low and narrow internal carina at or near the longitudinal midline of each of the four faces of the gently tapered periderm (Van Iten et al., 2020).Paraconularia planicostataoccurs in marine carbonates in the Upper Mississippian lower Windsor and lower Codroy groups in Nova Scotia and western Newfoundland, respectively (e.g., Bell, 1929; Stacy, 1953; Dix and James, 1988; Boehner et al., 1989; Boehner and Prime, 1993; Lavoie and Sami, 1998; Jutras et al., 2006; Ryan and Giles, 2017; Van Iten et al., 2020). The species is exceptionally abundant, with richly fossiliferous biohermal limestones containing up to approximately 20 specimens per 1000 cm3of host rock (Van Iten, unpublished observations)—a volumetric density matched by few other conulariid-bearing rock units.

Late Devonian shear-zone reactivation in the Canadian Appalachian orogen

Abstract Oblique accretion zones often display transpressive, strike-slip and transtensive structures of different orientations with respect to the convergence axis. The Late Devonian oblique collision of Meguma within the Canadian Appalachian orogen is often characterized as transpressive. However, the simultaneous opening of the Maritimes Basin indicates that the orogenesis also partitioned into an extensional component. In this context, few of the shear zones reactivated during this time period have been characterized while accounting for the possibility of strain partitioning. To do so, we characterize the kinematics and timing of deformation of the Eastern Highlands Shear Zone (EHSZ) and the Coinneach Brook Shear Zone (CBSZ) on Cape Breton Island, Nova Scotia, using a combination of U–Pb geochronology (zircon, monazite, xenotime and apatite) and 40 Ar/ 39 Ar geochronology in situ and step-heating experiments (amphibole, muscovite and biotite). Results show that the Silurian EHSZ was reactivated at c. 385–367 Ma and the CBSZ was formed at c. 395–369 Ma, both yielding oblique kinematics. Together, these structures accommodated the rapid exhumation of the Cape Breton Highlands during the docking of the Meguma terrane. This study thus highlights the heterogeneous distribution of transtensive and transpressive deformation during the Neoacadian Orogeny.

Response of the sea surface temperature to heatwaves during the France 2022 meteorological summer

Abstract. The summer of 2022 was memorable and record-breaking, ranking as the second hottest summer in France since 1900, with a seasonal surface air temperature average of 22.7 ∘C. In particular, France experienced multiple record-breaking heatwaves during the meteorological summer. As the main heat reservoir of the Earth system, the oceans are at the forefront of events of this magnitude which enhance oceanic disturbances such as marine heatwaves (MHWs). In this study, we investigate the sea surface temperature (SST) of French maritime basins using remotely sensed measurements to track the response of surface waters to the atmospheric heatwaves and determine the intensity of such feedback. Beyond the direct relationship between SSTs and surface air temperatures, we explore the leading atmospheric parameters affecting the upper-layer ocean heat budget. Despite some gaps in data availability, the SSTs measured during the meteorological summer of 2022 were record-breaking, the mean SST was between 1.3 and 2.6 ∘C above the long-term average (1982–2011), and the studied areas experienced between 4 and 22 d where the basin-averaged SSTs exceeded the maximum recorded basin-averaged SSTs from 1982 to 2011. We found a significant SST response during heatwave periods with maximum temperatures measured locally at 30.8 ∘C in the north-western Mediterranean Sea. Our results show that in August 2022 (31 July to 13 August), France experienced above-average surface solar radiation correlated with below-average total cloud cover and negative wind speed anomalies. Our attribution analysis based on a simplified mixed-layer heat budget highlights the critical role of ocean–atmosphere fluxes in initiating abnormally warm SSTs, while ocean mixing plays a crucial role in the cessation of such periods. We find that the 2 m temperatures and specific humidity that are consistently linked to the advection of warm and moist air masses are key variables across all the studied regions. Our results reveal that the influence of wind on heatwaves is variable and of secondary importance. Moreover, we observe that the incident solar radiation has a significant effect only on the Bay of Biscay (BB) and the English Channel (EC) areas. Our study findings are consistent with previous research and demonstrate the vulnerability of the Mediterranean Sea to the increasing frequency of extreme weather events resulting from climate change. Furthermore, our investigation reveals that the recurring heatwave episodes during the summer of 2022 had an undeniable impact on all the surveyed maritime areas in France. Our study therefore provides valuable insights into the complex mechanisms underlying the ocean–atmosphere interaction and demonstrates the need for an efficient and sustainable operational system combining polar-orbiting and geostationary satellites to monitor the alterations that threaten the oceans in the context of climate change.

Comparative analysis of National Ocean Strategies of the Atlantic Basin countries

In 2007 the European Union (EU) launched the Blue Book introducing the Integrated Maritime Policy (IMP) for the sustainable growth of the coastal regions of Member States. The IMP has several cross-cutting areas of intervention such as the Blue Growth Strategy, Maritime Spatial Planning, and Strategies for maritime basins. To ensure this policy’s implementation, the European Commission requested its coastal members to develop integrated maritime strategies. Furthermore, within the United Nations Decade of Ocean Science for Sustainable Development, it is also a priority of the EU to ensure compliance with the 2030 Agenda, in particular the SDG14. This study focuses on countries from the Atlantic Basin, namely France, Ireland, Portugal, Spain, and the UK (before Brexit) comparing key priorities and objectives of national ocean strategies of these countries and how they match IMP guidelines and the 2030 Agenda. The results show that one of the main focuses of these strategies is the mitigation and adaptation to climate change and nature conservation. On the other hand, desalination, exploration and prospection of oil and gas are the socioeconomic sectors of smaller significance. This study also demonstrated that Spain and UK’s ocean strategies cannot be considered as a national ocean strategy in the IMP concept. The national ocean strategy of Ireland was introduced almost 10 years ago, therefore can be considered outdated in several dimensions. France and Portugal are the only countries whose national ocean strategies are aligned with the objectives of the Atlantic Action Plan and the only ones that truly follow the guidelines of the EU Integrated Maritime Policy.

The Actual Security Climate in the Black Sea Basin

Abstract This paper analyses the context of security in the Black Sea basin area and its connections with the strategic, military, and economic aims of the main factors contributing to the region’s stability and security. The work debuted with some geographical and physical features of the maritime basin, switching the analysis to security actors. The article portrays the EU (European Union) and NATO (North Atlantic Treaty Organization) regarding the actual and past actions taken to enhance the region’s security and stability. Further, the article investigates the six riparian states through the military and strategic-oriented approach. The concluding part of the work exhibits a sharp insight beyond the sea basin area, and the work is closed by short concluding remarks.

Deformation of soft sediments and evaporites in a tectonically active basin: Bay St. George sub-basin, Newfoundland, Canada

The Bay St. George sub-basin of SW Newfoundland, part of the larger late Paleozoic Maritimes basin, formed under the influence of strike-slip faulting and the movement of evaporites. New stratigraphic correlations between Newfoundland and other late Paleozoic sub-basins illustrate the effects of both basement and salt movement. Coastal outcrops show complex combinations of synsedimentary, salt-related, and tectonic structures. Map relationships and dramatic thickness contrasts in the Tournaisian Anguille Group indicate that a large, concealed, NE–striking normal growth fault (Ship Cove fault) controlled sedimentation; the exposed Snakes Bight fault originated as a hanging-wall splay. Structures formed during, or soon after deposition include soft-sediment folds, boudins, clastic dykes, and millimetre-scale diapiric bulb structures, formed by overpressuring and liquidization of sediment. These suggest that the sub-basin was tectonically active throughout deposition. Evaporite-related deformation is recorded in the Visean Codroy Group and overlying strata. Comparisons between outcrop and subsurface suggests that significant amounts of evaporite were removed from exposed sections by halokinesis and solution. Complex outcrop relationships indicate salt welds, and suggest that units of the upper Codroy and overlying Barachois groups represent fills of minibasins that subsided into thick evaporites. Field relationships suggest tectonic inversion deposition related to E-W dextral strike slip motion that affected the entire Maritimes basin in the Serpukhovian, producing reverse-sense offsets and contractional folds. Many of the structures in the Bay St. George sub-basin, previously interpreted as post-depositional and purely tectonic, were formed by deformation of unlithified sediment and ductile evaporites during basin development.

Carboniferous tetrapod footprint biostratigraphy, biochronology and evolutionary events

Abstract The Carboniferous record of tetrapod footprints is mostly of Euramerican origin and provides the basis for a footprint biostratigraphy and biochronology of Carboniferous time that identifies four tetrapod footprint biochrons: (1) stem-tetrapod biochron of Middle Devonian–early Tournaisian age; (2) Hylopus biochron of middle Tournaisian–early Bashkirian age; (3) Notalacerta–Dromopus interval biochron of early Bashkirian–Kasimovian age; and (4) Dromopus biochron of Kasimovian–early Permian age. Particularly significant is the Carboniferous tetrapod footprint record of the Maritimes basin of eastern Canada (New Brunswick, Nova Scotia and Prince Edward Island), which encompasses well-dated and stratigraphically superposed footprint assemblages of Early Mississippian–early Permian age. The Carboniferous tetrapod footprint record provides these important biostratigraphic datums: (1) oldest temnospondyls (middle Tournaisian); (2) oldest reptiliomorphs, likely anthracosaurs (middle Tournaisian); (3) oldest amniotes (early Bashkirian); and (4) oldest high-fibre herbivores (Bashkirian). Carboniferous tetrapod footprints thus provide significant insight into some major events of the Carboniferous evolution of tetrapods.

Paleotethyan faunal/floral evidence in the Mississippian Maritimes Basin of Canada: An overview

AbstractIn this study, middle to late Mississippian microfossil assemblages from the Maritimes Basin of eastern Canada (Nova Scotia, SW Newfoundland, and New Brunswick) are closely compared to those from Western Paleotethys basins. The comparison is focused mainly on foraminifers and calcareous algae. Most foraminifers and algae described from the Maritimes Basin are considered cosmopolitan, and the occurrence in western Europe and northern Africa of taxa previously considered endemic to the North America Realm suggests a close paleobiogeographic relationship. This European/African correlation is further supported by other foraminiferal/algal taxa, the importance of which were previously overlooked, including:Plectogyranopsisex gr.P. hirosei(Okimura, 1965),MikhailovellaGanelina, 1956,Koktjubina windsorensis(Mamet, 1970),Polysphaerinella bullaMamet, 1973,MstiniaDain in Dain and Grozdilova, 1953,HaplophragminaReitlinger, 1950,OmphalotisShlykova, 1969,PseudolituotubaVdovenko, 1971,PseudoendothyraMikhailov, 1939,Saccamminopsis(Sollas, 1921) Vachard and Cózar, 2003,KamaenellaMamet and Roux, 1974, andAnthracoporellopsisMaslov, 1956. Some species recorded in the Maritimes Basin have been typically recorded in Britain and Ireland in the southern platform of Laurussia. This implies a connection via the Rhenohercynian Ocean, whereas statistical analyses suggest that Maritimes Basin assemblages are closer to those of the Gondwana platform, which could have been established via the Paleotethys Ocean, and also with terranes northwest of the Variscan Front, in which its most logical connection should be with a still-open Rheic Ocean during the Visean and early Serpukhovian. Those taxa demonstrate a more-or-less continuous faunal and microfloral interchange between the Maritimes Basin and the Western Paleotethys paleobiogeographic realm. Furthermore, the width of the Paleotethys and Rheic oceans separating these regions is not considered excessive, particularly during the late Visean and early Serpukhovian.

Stratigraphy and sedimentology of the Pennsylvanian Grande Anse Formation, Cumberland Basin, eastern Canada: its relationship to salt tectonics and coeval strata of the Joggins World Heritage Site

The Cumberland Basin is one of several sedimentary basins composing the late Paleozoic Maritimes Basin complex of eastern Canada. Pennsylvanian salt tectonics in the Cumberland Basin caused two salt mini-basins to evolve on either side of the Minudie Anticline, a salt wall. South of the wall (Athol Syncline), along the Joggins World Heritage shoreline, an ∼3000 m succession of strata (Little River, Joggins, Springhill Mines, and Ragged Reef formations) accumulated conformably on the Boss Point Formation. North of the wall (Black Point sub-basin), the biostratigraphically equivalent, but mostly unstudied, ∼600 m thick succession of Grande Anse Formation lies in angular unconformity on folded and faulted Boss Point and basal Little River formations. Grande Anse Formation sedimentology indicates four lithofacies associations: floodplain (LA1), braided channel (LA2), sheet flood (LA3), and debris flow deposits (LA4). One possible model has the Black Point sub-basin with its own hydrological system, completely separated from the Athol Syncline. A low subsidence rate combined with the low sedimentation rate produced the ∼600 m thick sand- and mud-prone succession that was contemporaneous with the ∼3 km succession to the south. The second model proposes that north of the salt wall was exposed to erosion during accumulation of Joggins and Springhill Mines formation strata to the south. Subsequently, the sediment of the lithologically similar Ragged Reef and Grande Anse formations either (i) onlapped to the north, unconformably on the folded Boss Point; or (ii) unconformably–disconformably on the underlying strata after a period of time indistinguishable in the biostratigraphic record.

Sequence stratigraphy of the late Carboniferous Clifton Formation, New Brunswick

The Maritimes Basin of Atlantic Canada contains a rich record of Pennsylvanian cyclothems. Previous studies have focused on rapidly subsiding depocenters in the central part of the basin where Carboniferous successions feature cyclic alternations between terrestrial and marginal marine strata. In contrast, the Pennsylvanian Clifton Formation was deposited on the relatively stable New Brunswick platform and contains almost entirely terrestrial strata. Although early studies of the Clifton Formation noted a cyclic architecture, particularly within Member B, this unit has remained understudied. We provide a sedimentological and sequence stratigraphic framework for the lower 85 m of Member B and interpret our results relative to a broader regional framework. Near the base of the study interval, the highstand systems tract is composed of red floodplain mudrocks; overlying sequence boundaries are composed of calcretes and (or) channels. The transgressive systems tract and maximum flooding surface are represented by coals and aquatic bivalve-bearing mudrocks. Moving upward through the section, the architecture of the highstand systems tract remains largely unchanged while sequence-bounding paleosols become less well developed, the transgressive systems tract becomes thinner and eventually not preserved, and the maximum flooding surface is only occasionally preserved, possibly represented by carbonaceous shales. These changes in cyclic architecture may be attributed to changes in the magnitude of glacioeustatic fluctuations, climate, and (or) the accommodation/sediment supply ratio. The results of this study show that the Clifton Formation represents the terrestrial/proximal endmember for cyclicity in the Maritimes Basin and provide new insight into paleotopography as a possible control on cyclothem architecture.

Black sea marine litter pollution related to naval operations

The Black Sea, due to its weak exchange of waters and poor vertical circulation, has an increased sensibility to pollution. Even though this maritime basin is subject to numerous regulations at the national, regional, and international levels, the pollution issue is still actual and stringent. The present paper analyses the findings of three studies focused on marine litter issues and provide, in the concluding part, few directions which can improve the pollution prevention and containment effort. As the studies related to Black Sea litter pollution are scarce and fragmented, the authors took the opportunity and analyzed three different studies conducted in different periods and concluded that a significant part of marine debris is related to naval operations.

Age correlation of Large Igneous Provinces with Devonian biotic crises

Abstract Large Igneous Provinces (LIPs) are emerging as a significant driver of short duration climatic change including mass extinctions. Here we compare the record of LIPs against the timing of Devonian biotic crises that are well recorded in the numerous anoxia events throughout this period. The largest LIPs are two-pulse events at ca. 370 and ca. 360 Ma that are present in both Siberia (Yakutsk-Vilyui LIP) and Baltica (Kola-Dnieper LIP) and correlate with the Kellwasser anoxia events (late Frasnian) and Annulata or Dasberg and Hangenberg anoxia events in the late/latest Famennian. The regionally significant Altai Sayan LIP is only approximately dated at c.400 Ma and within uncertainties could be linked to either (or both?) the c. 405 Ma Chebbi or Atopus anoxia events near the basal Emsian (associated with graptolite extinction) or the c. 385–390 Ma group of anoxia events in the Eifelian or Givetian. Additional magmatic events that are less precisely dated are: 1) the c. 400–345 Ma Kedon magmatism of the Omolon craton, possibly linked with the Yakutsk-Vilyui event, 2) 380–330 Ma Maritimes (Magdalen) basin event of the Appalachian region of eastern Canada and adjacent US, 3) middle-late Devonian Selwyn basin alkaline magmatism of northwestern Canada, and 4) the Ordovician - late Silurian- possibly Devonian Soltan Maidan event Iran. However, more precise dating is required for each of these magmatic events before they can be properly compared with the Devonian biotic crisis record.

Derivation of the Early Carboniferous Wedgeport pluton by crystal fractionation of a mafic parental magma: a rare case of an A-type granite within the Meguma terrane (Nova Scotia, Canada)

AbstractThe Cambrian–Ordovician metasedimentary rocks of the Meguma terrane (Canadian Appalachians) were extensively intruded by silicic plutons during Middle Devonian to Early Carboniferous times. Syn-plutonic but volumetrically minor mafic-ultramafic intrusions were also emplaced. In most localities, the silicic plutons and mafic-ultramafic intrusions do not appear to be petrogenetically related and are likely derived from different sources. The Attwoods Brook gabbronorite of SW Nova Scotia yielded an in situ zircon weighted-mean 206Pb–238U age of 357.9 ± 3.3 Ma that is within the uncertainty of the age of the neighbouring Wedgeport pluton (357 ± 1 Ma). The Wedgeport pluton is a rare example of a mantle-derived, peraluminous A-type granite within the Meguma terrane. The similar ages and Nd isotopes of the Attwoods Brook gabbronorite (εNd(t) = +1.1 to +4.0) and Wedgeport pluton (εNd(t) = +2.1 to +3.3) suggest the two intrusions are petrogenetically related. Fractional crystallization modelling demonstrates that a parental magma similar to the Attwoods Brook gabbronorite can produce residual silicic liquids that resemble the granites of the Wedgeport pluton, indicating that they could be members of the same intrusive complex. The emplacement of the gabbronorite and Wedgeport pluton occurred during a period of tensional plate stress that was contemporaneous with rifting of the Maritimes Basin that produced the Fountain Lake continental flood basalts and A-type granites of the Cobequid Highlands within the Avalon terrane. It is possible that the Early Carboniferous rocks of SW Nova Scotia are related to the rifted-related magmatism within the Maritimes Basin.

Using permutational and multivariate statistics to understand inorganic well water chemistry and the occurrence of methane in groundwater, southeastern New Brunswick, Canada

Concerns over possible impacts from the rapid expansion of unconventional oil and natural gas (ONG) resource development prompted a regional domestic well sampling program focusing on the Carboniferous Maritimes Basin bedrock in southeastern New Brunswick, Canada. This work applies recent developments in robust multivariate statistical methods to overcome issues with highly non-Gaussian data and support the development of a conceptual model for the regional groundwater chemistry and the occurrence of methane. Principal component analysis reveals that the redox-sensitive species, DO, NO3, Fe, Mn, methane, As and U are the most important parameters that differentiate the samples. Permutation-based MANOVA and ANOVA testing revealed that geology was more important than geographic location and topography in influencing groundwater composition. The statistical inferences are supported by chemistry trends observed in relation to road de-icing salt and other saline sources. However, source differentiation between Carboniferous brines, entrapped post-glacial marine water and modern seawater cannot be made. Furthermore, Cl:Br ratios lower than those of seawater or regional brines suggest an origin related to the diagenesis of organic-rich sediment and that the groundwater may be influenced by local low permeability units.Combined spatial, statistical and chemical analysis shows that, while trace or low levels of methane, <1 mg/L, are found ubiquitously throughout the Maritimes Basin, elevated concentrations, >1 mg/L, are associated with the Horton Group, consistent with it being the host and inferred source of ONG resources in the province. The highest methane concentrations (14–29 mg/L) were detected in the region with a complex history of cycles of uplift and erosion which, in some locations, resulted in the juxtaposition at the surface of the Horton Group with several other groups of the Maritimes Basin. It is thought that proximity to the Horton Group can lead to naturally high methane concentrations in non-ONG-bearing units.

New insight on the geometry and evolution of the Moncton sub-basin from 3D seismic reflection data in the McCully area, New Brunswick, Canada

Abstract Within the Maritimes Basin of eastern Canada, the onshore Moncton sub-basin is one of the NE-trending second-order depocenters that recorded a complex tectonic history from Late Devonian to Late Carboniferous. Analysis of a 3D seismic volume in the McCully gas field area exemplifies the complex interplay between mainly continental sedimentation and several tectonic episodes that contribute to a net extension or shortening in an overall strike-slip setting. The new interpretation demonstrates the role of normal faults oblique to the sub-basin axis in initial phases of sub-basin development and their influence on the deposition of the Upper Devonian-Lower Mississipian Horton Group sediments. A subsequent episode of transpression is recorded by syn-folding growth strata (base of the Mississipian Sussex Group) preserved on both flanks of an anticline that belongs to a fold system that shows an en echelon geometry relative to sub-basin bounding faults. Deposition of a marine interval (Middle Mississipian Windsor Group), including evaporitic strata is succeeded by an halokinetic growth succession (Upper Mississipian-Pennsylvanian Mabou Group) found in minibasins that formed through drape folding (downbuilding) in response to salt-walls development. This polyphased history illustrates the complexity of strike-slip basins that are often controlled by structures with different geometry and kinematics in time and/or space.

Low-angle faulting in strike-slip dominated settings: Seismic evidence from the Maritimes Basin, Canada

The Maritimes Basin is an upper Paleozoic sedimentary basin centered in the Gulf of St. Lawrence (Canada). Early phases of basin formation included the development of partly connected sub-basins bounded by high-angle faults, in an overall strike-slip setting. Interpretation of reprocessed seismic reflection data indicates that a low-angle detachment contributed to the formation of a highly asymmetric sub-basin. This detachment was rotated toward a lower angle and succeeded by high-angle faults that sole into the detachment or cut it. This model bears similarities to other highly extended terranes and appears to be applicable to strike-slip and/or transtensional settings.

Tectonostratigraphic and petrogenetic setting of late Mississippian volcanism in eastern Canada

In the aftermath of the Middle Devonian Acadian Orogeny, a thick mafic body is inferred to have been emplaced at the base of the crust during development of the Maritimes Basin complex in eastern C...