Northern Nova Scotia Research Articles

Cooling in the Gulf of St. Lawrence and estuary region at 9.7 to 7.2 14C ka (11.2–8.0 cal ka): Palynological response to the PBO and 8.2 cal ka cold events, Laurentide Ice Sheet air-mass circulation and enhanced freshwater runoff

An examination of post-Younger Dryas (YD) pollen stratigraphies in the Gulf of St. Lawrence and St. Lawrence estuary region reveals features in the pollen records that represent breaks in the normal vegetation succession, widespread vegetation suppression, and a delay in migration of plant taxa between 9.7 and 7.2 14C ka (11.2 and 8.0 cal ka). The domination of Alnus crispa at sites bordering the St. Lawrence estuary–Gulf region in Gaspésie and northern New Brunswick within this timeframe represents a diversion from the typical vegetation progression from Picea and/or Populus or Picea/Betula to Pinus and/or Betula, and signifies a shift to a cooler, drier climate. Coinciding with the A. crispa expansion and domination in that region was the contraction of Picea populations in other areas. In southwestern New Brunswick and eastern and southeastern Nova Scotia, Picea was replaced by the first appearance of tree birch, B. papyrifera; whereas in western and southwestern Newfoundland, Picea gave way to a resurgence of shrub birch, Betula glandulosa. The Picea contraction and immediate resurgence of Betula represents cooling, and is reliably dated at 9720 ± 110 14C BP (10,800–11,240 cal BP) in southwest Newfoundland. This first post-YD episode of widespread cooling is correlated with the North Atlantic Preboreal Oscillation (PBO) centered around 9650 14C BP (10,900–11,180 cal BP) in the adjacent Great Lakes region. Sites exposed to winds from the Gulf of St. Lawrence in eastern New Brunswick, Prince Edward Island, and northern Nova Scotia show a lingering persistence of Picea and delay in arrival of Pinus to 8.0 and 7.7 14C ka (9.0 and 8.4 cal ka), yet Pinus was dominant as early as 9.4 14C ka (10.6 cal ka) in southwestern New Brunswick. At the same time, tundra vegetation persisted at high elevations in western and southwestern Newfoundland only to be replaced by upslope migration of shrub–birch heath by 8 14C ka. Prolonged broad-scale cooling to 8 14C ka and to as late as 7.7 14C ka extended up to 200 km inland in areas exposed to the St. Lawrence estuary and Gulf region and was in response to strong, cold, dry anticyclonic winds coming off the retreating Laurentide Ice Sheet in combination with enhanced freshwater runoff through the Gulf of St. Lawrence. The end of the period of prolonged cooling and onset of regional warming coincided with the diversion of western Canada runoff and Agassiz–Ojibway drainage to Hudson Bay and reduced effect or final break-up of the Laurentide Ice Sheet. Several sites document a subsequent cold shift, that interrupted regional warming at 7650 to 7200 14C BP (8400 to 8000 cal BP), and which is variously represented by the suppression of Pinus and resurgence of Picea, sometimes with A. crispa (Québec–Maritime region), or by an abrupt decrease of Picea and resurgence of Betula (western Newfoundland). This second post-YD cool interval is equated with the 8200 cal BP cold event registered in the Greenland ice isotopic record.

The Spindle Tree, <em>Euonymus europaea</em> L. (Celastraceae): A Newly Naturalized Shrub in Nova Scotia

Over 100 plants, including over 750 individual shoots, of Euonymus europaea L. are reported from the Town of Antigonish in northern Nova Scotia. Plants were found in five discrete areas separated by 200-1000 m. A few individuals at one site may represent human planting; however, over 90% of plants occur on waste ground or in dense shrubbery where natural colonization has occurred. Many individuals were observed in fruit in the fall of 2005, and over 95% of the plants had well developed buds and flowers in May and early June 2006. Euonymus europaea is considered a newly naturalized species for the flora of Nova Scotia.

Factors Associated with PAP Testing in Adolescents in Northern Nova Scotia

To determine relationships of socio-economic factors and contraceptive behaviours with PAP testing in sexually active women aged 15-19 who had received physician services in northern Nova Scotia in the previous year.A cross-sectional survey was completed by adolescents attending four high schools in three counties in northern Nova Scotia. Questions concerned contraceptive behaviours, socio-economic status and health services use, including PAP testing. Associations of socio-economic factors and contraceptive behaviours with receipt of a PAP test in the previous year were examined in women who were sexually active for at least one year, and who also had visited a physician during the previous year.One thousand and ninety adolescent women aged 15-19 completed surveys, with a response rate of 91%. Of the 396 (36.3%) who reported being sexually active and having visited a physician in the previous year, 393 provided information about PAP testing. Of these, 214 (54.5%) reported receiving a PAP test. Factors associated with PAP testing included viewing one's family as advantaged and living in a major town as opposed to a more rural area. Compared with using hormonal contraception, using either condom without other effective contraception or no effective contraception at last intercourse were negatively associated with PAP testing.These findings suggest that physicians use hormonal contraception as a cue for PAP testing in adolescent women. Guidelines call for regular PAP testing of sexually active adolescents, and efforts to increase adolescent PAP testing should include professional development to increase recognition of sexual activity.

Incidence of Mentum Deformities in Midge Larvae (Diptera:Chironomidae) from Northern Nova Scotia, Canada

Deformities in the mouthparts of larval Chironomidae, particularly of the teeth on the mentum, have been proposed as a bioindicator of sediment quality and environmental stress. Most work to date has concentrated on relatively few abundant, responsive genera common in soft-bottom lakes. We examined mentum deformities in 25 genera of Chironominae, Orthocladiinae and Diamesinae (one genus) from streams and a lake in rural Nova Scotia where farming and forestry are the principal land uses. Incidence of deformity at similar stream sites varied across genera from zero to >10%. Average frequencies of deformity across all three subfamilies at sites with no known sources of contamination ranged from <4% to 8%, and increased to nearly 15% at a site receiving treated municipal sewage effluent. Differences in chironomid community structure and rates of leaf litter decomposition above and below the sewage effluent outfall were congruent with the difference in mentum deformities. Frequencies of deformity observed here are an order of magnitude greater than in similar studies of rural areas. Low-level stress from agriculture or forest harvesting may be widespread in rural regions even in aquatic ecosystems that are seemingly free of industrial discharges or sediment contamination.

Provenance of fossiliferous clasts in Carboniferous conglomerate, Isle Madame, southern Cape Breton Island, Nova Scotia

Fossiliferous clasts occur in Carboniferous conglomerate in the Horton Group on western Isle Madame and in the Mabou Group on eastern Isle Madame. Most of the clasts (21 of 23 examined) are calcareous siltstone and sandstone that contain Silurian – Lower Devonian faunas comparable to those in the Arisaig area, northern mainland Nova Scotia, although the lithologies are coarser grained and less calcareous than those of the Arisaig section. These middle Paleozoic faunas are well constrained to the Silurian (uppermost Llandovery through Pridoli) and lowest Devonian and are characteristic of those known from shallow siliciclastic-dominated platforms of the Avalon microcontinent in Wales and England. The remaining two clasts have abundant inarticulate brachiopod shells that indicate provenance from Middle Cambrian proximal marine facies on the Avalonian marginal platform. No clasts were found that are likely to have been derived from the Torbrook Formation, and thus from the Meguma terrane in southwestern Nova Scotia, as has been previously reported. The association of relatively large, reworked fossiliferous clasts in Carboniferous conglomerate on Isle Madame suggests local derivation from lower and middle Paleozoic units not presently exposed, although probably present as subcrop under the Carboniferous units, in southwestern Cape Breton Island and adjacent mainland Nova Scotia.

Younger Dryas glacial advance in the southern Gulf of St. Lawrence, Canada: analogue for ice inception?

In the summer of 1999, the Maritimes and Northeast Pipeline Company excavated a 3‐m‐deep trench across northern Nova Scotia exposing a continuous transect of surficial deposits along a 237‐km corridor. A Lateglacial palaeosol with preserved A horizon (peat and wood) buried under 2–10 m of surface till consisted mainly of herbaceous plant material with few large wood fragments. Large pieces of wood from two sites yielded conventional radiocarbon ages of 10.9 14C kyr BP (GSC‐6435) and 10.8 14C kyr BP (GSC‐6419). Previous to these finds, only a few localities were known to reveal till overlying peat, so the extent of Younger Dryas (YD) glaciers could not be clearly established. Glacial flow lines indicated by fabric and fluting of the YD surface till sheet in northern Nova Scotia and ice‐marginal deposits imply an ice cap centred over eastern P.E.I. and the southern Gulf of St. Lawrence. This glacier also dammed a series of glacial lakes against the highland‐rimmed west coast of Cape Breton Island. Glaciers developed and advanced during the YD in the uplands and offshore shelf areas from small remnants of Late Wisconsinan ice. Renewed ice growth was enabled by increased precipitation and local cooling in the Gulf of St. Lawrence due to deflection of the jet stream and expanded sea‐ice cover in the North Atlantic. The YD may provide an analogy to glacier development in Maritime Canada during the interglacial/glacial transition.

Socio-economic Factors and Adolescent Sexual Activity and Behaviour in Nova Scotia

Little is known about associations of adolescents' socio-economic status (SES) and their sexual activity and risk behaviours. This study examined these associations in Nova Scotia adolescents aged 15-19. Students at four high schools in northern Nova Scotia completed surveys examining relationships of family SES factors and: 1) sexual activity (having had vaginal or anal intercourse, intercourse before age 15 (early intercourse)); and 2) risk behaviours (use of contraception/condoms, number of partners and unplanned intercourse after substance use). Of students present when the survey was administered, 2,135 (91%) responded. Almost half (49%) had had vaginal intercourse, and 7% anal intercourse. In univariate analysis for young women, non-intact family structure and lower parental education were associated with having vaginal, anal and early intercourse. Female risk behaviours showed no significant univariate associations with SES. Young men had univariate associations of family structure, lower maternal education and paternal unemployment with early intercourse, and lower paternal education with anal intercourse. Condom use was higher for young men with employed fathers; those living with both parents less often had >1 sexual partner. In multivariate analysis, most SES associations with females' sexual activities held, while most for males did not, and few associations of SES and risk behaviours were seen for females. Indicators of lower SES are associated with sexual activity in young women. Sexual risk behaviours are not often associated with SES in females, though they are more so in males. These findings have implications for sexual health promotion and health services.

Stratigraphy and structure of the Horton Group, Lochaber-Mulgrave area, northern mainland Nova Scotia

The Lochaber-Mulgrave area of northern mainland Nova Scotia is underlain by rocks of the Late Devonian - Early Carboniferous Horton Group, in faulted contact with older Devonian and Silurian rocks to the south and west, and younger Carboniferous rocks to the north and east. The Horton Group is divided into (from oldest to youngest) the Clam Harbour River, Tracadie Road, Caledonia Mills, and Steep Creek formations, with a total thickness of at least 4000 m. These units were deposited in a variety of braided fluvial and shallow to deep lacustrine environments, and show lithological and stratigraphic similarities to the Horton Group elsewhere in Nova Scotia. Sparse palaeonto-logical data from macrofossils and spores indicate an age range from Famennian to late Tournaisian. Compared to elsewhere in Nova Scotia, the Horton Group in the Lochaber-Mulgrave area is more deformed and metamorphosed, especially in the southern part of the area near the Roman Valley Fault. The time of regional deformation and meta-morphism is constrained to ca. 340– 335 Ma by whole-rock 40Ar/39Ar dating of slate in the Clam Harbour River and Tracadie Road formations. Regional deformation and metamorphism may have resulted from burial by older rocks of the Guysborough block, thrust over the Horton Group in the Lochaber-Mulgrave area from the south as a result of transpression at a restraining bend along the Chedabucto-Roman Valley fault system during juxtaposition of the Avalon and Meguma terranes. RÉSUMÉ Le secteur de Lochaber-Mulgrave dans le nord de l'intérieur de la Nouvelle-Écosse repose sur des roches du groupe du Dévonien tardif au Carbonifère précoce de Horton, en contact faillé avec des roches du Dévonien et du Silurien au sud et à l'ouest, et avec des roches carbonifères au nord et à l'est. Le groupe de Horton se subdivise en (de la plus ancienne à la plus récente) formations de Clam Harbour River, de Tracadie Road, de Caledonia Mills et de Steep Creek, d'une épaisseur totale d'au moins 4 000 mètres. Ces unités se sont déposées au sein de divers environnements lacustres allant de peu profonds à profonds et d'environnements fluviaux anastomosés; elles présentent des similarités lithologiques et stratigraphiques avec le groupe de Horton ailleurs en Nouvelle-Écosse. Des données paléontologiques éparses tirées de macrofossiles et de spores révèlent une fourchette d'âges du Famennien au Tournaisien tardif. Comparativement aux autres régions de la Nouvelle-Écosse, le groupe de Horton dans le secteur de Lochaber-Mulgrave est plus déformé et métamorphisé, en particulier dans la partie méridionale du secteur, près de la faille de la vallée Roman. Le moment de la déformation et du métamorphisme régionaux se trouve restreint à environ 340-335 Ma par la datation 40Ar/39Ar de roche totale de l'ardoise dans les formations de Clam Harbour River et de Tracadie Road. La déformation et le métamorphisme régionaux pourraient avoir découlé de l'enfouissement de roches plus anciennes du bloc de Guysborough, qui chevauche le groupe de Horton dans le secteur de Lochaber-Mulgrave à partir du sud, par suite d'une transpression dans une inflexion de retenue le long du système de failles de Chedabucto-vallée Roman pendant la juxtaposition des terranes d'Avalon et de Meguma

Crustal structure of the northern Nova Scotia rifted continental margin (eastern Canada)

The Nova Scotia continental margin off eastern Canada marks a transition from a volcanic to a nonvolcanic style of rifting. The northern (nonvolcanic) segment of the margin was studied by a 490‐km‐long refraction seismic line with dense air gun shots, coincident with previous deep reflection profiles. A P wave velocity model was developed from forward and inverse modeling of the wide‐angle data from 19 ocean bottom seismometers and coincident normal incidence reflection profiles. The continental crust has a maximum thickness of 36 km and is divided into three layers with velocities of 5.7–6.9 km/s. Crustal thinning down to 3 km occurs in a 180‐km‐wide zone and the sediment cover in this area is up to 15 km thick. Farther seaward, a 150‐km‐wide transition zone is observed with a 5‐km‐thick lower layer (7.2–7.6 km/s) interpreted as partially serpentinized mantle. At the landward end, this layer is overlain by highly altered continental crust (5.4 km/s) extending up to the seaward limit of the Jurassic salt province. Farther seaward, the upper layer is interpreted as exhumed and highly serpentinized mantle (5.1 km/s) separated from the lower layer by subhorizontal reflectivity, which probably represents a serpentinization front. Oceanic crustal thickness is 4 km with layer 2 velocities of 4.6–5.0 km/s. Layer 3 velocities of 6.4–6.55 km/s are lower than typical lower oceanic crust velocities but consistent with a low magma supply and increased tectonism as observed on the reflection profile. This reduced magma production might be related to the proximity of the Newfoundland transform margin.

CHANGES IN TRACKING TUBE USE BY SMALL MAMMALS OVER TIME

Tracking tubes offer an efficient alternative to live-trapping for studies that require very large sample sizes. However, it is necessary to know how small mammals change in their tendency to enter tracking tubes with time. We measured this change in response in a region of boreal forest in northern Nova Scotia, Canada, in 1994–1998. Over 4 weeks, small mammals increased in their tendency to enter tubes, with no difference in response among species. Thus, when designing studies using tracking tubes, one needs to adjust for differences in duration—one cannot simply calculate a tracks/tube-night measure. We show how to statistically remove the effect of duration.

Association of Socio-economic Factors with Health Risk Behaviours Among High School Students in Rural Nova Scotia

To determine the association of socio-economic (SES) factors with risk behaviours among adolescents. A cross-sectional survey was carried out on students in four high schools in northern Nova Scotia, Canada. Associations between SES variables and substance use behaviours, having early intercourse and suicide attempt in the past year were examined using multivariate analysis (logit regression). Negative binomial regression was performed for associations of SES with a total risk score summing risk behaviours. Participants included 2,198 students (48% males; 52% females) ranging in age from 14 to 20 years. Almost 25% of youth smoked regularly, 19% of males smoked marijuana > or = 10 times monthly, more than 40% of males regularly drank excessively, and 10% of students > 14 years old had had intercourse before age 15. Smoking was the behaviour most often associated with lower SES in both genders. Mother's not being employed was protective against all substance use variables except driving after drinking. Living both with lone mother and in any family arrangement other than with both parents was associated with smoking, using marijuana, and early sex. Higher risk score was associated with living with a lone mother or other family arrangement. Lower risk score was associated with father having more than high school education and mother not working. Lower socio-economic status is associated with adolescent risk behaviours. These findings point to the importance of these factors to risk-taking in youth, their relevance to social policy, and also their importance as factors to consider in targeted interventions.

Behavioural evidence for social units in long-finned pilot whales

In general, mammal species show geographic or social dispersal by one or both sexes. Long-term behavioural observations and genetic evidence have confirmed that fish-eating resident killer whales, Orcinus orca, are a rare exception. Female and male offspring travel with their mothers for their whole lives: this is natal group philopatry. It is suspected that pilot whales, Globicephala spp., also follow this social pattern, but longitudinal data on the social structure of live long-finned pilot whales, Globicephala melas, are rare. We observed G. melas through July and August of 1998–2000 off northern Nova Scotia, Canada. Estimated group sizes ranged from 2 to 135 (mean = 20, SD = 17, median = 15, n = 249). We distinguished 322 individuals on the basis of distinctive marks on the dorsal fin, with estimated mark rates of 0.336 (proportion) (SE = 0.041) and 0.352 (mean of estimates) (SE = 0.036). Permutation testing rejected the null hypothesis of random association between individuals (p &lt; 0.0005). The best fit model of the standardized lagged association rate suggests short-term associations of individuals over hours to days and long-term associations with a subset of those individuals over years. When scaled according to mark rate, sets of long-term associates average approximately 11–12 individuals, a much lower estimate than that presented previously from drive-fishery data from the Faroe Islands. Genetic sampling of behaviourally studied individuals is recommended.

Suicidal Behaviours Among Adolescents in Northern Nova Scotia

To estimate the 12-month prevalence of suicidal behaviours by gender and to investigate the gender-specific factors associated with suicidal behaviours and to describe health service utilization by suicidal adolescents. This was a cross-sectional study. The baseline data of the Adolescent Health Study conducted in northern Nova Scotia were used. Female students were more likely to report suicidal behaviours than male students (p < 0.005). There was no gender difference in injurious suicide attempts. Depression was the strongest risk factor for suicidal behaviours in the two genders (p < 0.005). Female students who reported drug use and living in a non-intact family were at higher risk of suicide attempts. Low self-esteem was positively associated with suicidal ideation and suicide planning among male students. Suicidal girls were more likely to seek professional help for emotional disturbance than boys. Family doctors were the most frequently contacted professional by suicidal adolescents. Some factors associated with suicidal behaviours among adolescents may be gender specific. Suicidal behaviours have been considered a depressive symptom. Most suicidal students, however, had not contacted a health professional for an emotional problem in this population. This presents challenges for prevention of suicidal behaviours among adolescents.

Suicidal behaviours among adolescents in northern Nova Scotia: Gender difference, risk factors and health service utilization

Objectifs : Estimer la prevalence sur 12 mois des comportements suicidaires selon le sexe, etudier les facteurs propres a chaque sexe associes a ces comportements et decrire l'utilisation des services de sante par les adolescents suicidaires. Methode : Etude transversale fondee sur les donnees de reference d'une etude sur la sante des adolescents menee dans le nord de la Nouvelle-Ecosse. Resultats : Les eleves de sexe feminin etaient plus susceptibles que les eleves de sexe masculin de mentionner des comportements suicidaires (p<0,005). Il n'y avait aucune difference entre les sexes dans le nombre de tentatives de suicide avec blessures. La depression etait le principal facteur de risque de comportement suicidaire chez les deux sexes (p<0,005). Les filles qui disaient consommer des drogues et vivre dans une famille dissociee couraient un risque plus eleve de commettre des tentatives de suicide. La faible estime de soi etait positivement associee aux idees suicidaires et aux projets de suicide chez les garcons. Les filles suicidaires etaient plus susceptibles que les garcons de chercher de l'aide professionnelle pour leurs troubles affectifs. Les medecins de famille etaient les professionnels les plus souvent contactes par les adolescents suicidaires. Conclusions: Certains facteurs associes aux comportements suicidaires chez les adolescents peuvent etre propres a l'un ou l'autre sexe. On considere les comportements suicidaires comme un symptome de depression. Dans la population a l'etude, cependant, la plupart des eleves suicidaires n'avaient pas contacte un professionnel de la sante en reponse a un probleme affectif. Ceci presente un defi pour la prevention des comportements suicidaires chez les adolescents.

Genetic Relationships among Lowbush Blueberry Genotypes as Determined by Randomly Amplified Polymorphic DNA Analysis

Twenty-six genotypes of lowbush blueberry (Vaccinium angustifolium Aiton) representing four geographical zones (Maine, United States; New Brunswick, northern Nova Scotia, and western Nova Scotia, Canada) were selected to obtain DNA fingerprints and to estimate genetic similarity by randomly amplified polymorphic DNA analysis. The genotypes were either native accessions or selections from crosses involving native accessions as parents or grandparents. Thirty 10-base RAPD primers were initially screened; 11 proved to be polymorphic, resulting in 73 consistent RAPD bands. All 26 genotypes could be distinguished by their unique RAPD banding patterns and three unlabeled samples were correctly identified. The RAPD band data set was analyzed with Genstat5 to calculate similarity and distance matrices. Average similarity across all genotypes was 56%. Results from average linkage cluster analysis were used to construct a dendogram which demonstrated six main clusters with an average similarity linkage of 70%. The selection `Fundy' and its parent `Augusta' clustered at 77% similarity. The corresponding principal coordinate analysis supported the clusters and identified two distinct outliers. There was a small association by geographic grouping for five genotypes from Maine. It was concluded that RAPD analysis is a useful tool for genotypic identification and estimates of genetic similarity in lowbush blueberry.

Silurian spores and cryptospores from the arisaig group, Nova Scotia, Canada

The Arisaig Group in northern mainland Nova Scotia has the most complete sequence of Silurian, fine grained, siliciclastic, near‐shore marine sediments in Western Avalonia. In this setting, the Arisaig Group received a nearly continuous supply of autochthonous marine and allochthonous nonmarine palynomorphs. One hundred and seventy‐seven samples, ranging in age from latest Ordovician?‐early Llandovery to Prídolí (Beechhill Cove to Stonehouse formations) yield the most diverse spore assemblage yet known from the Silurian of North America. This paper describes the spores and cryptospores and reexamines age relationships of the Arisaig Group, placing both within context of early land plant evolution. Thirty‐six species of spores and cryptospores were found in the Arisaig Group. Six new species are Ambitisporites marginatus sp. nov., A. capitaneus sp. nov., Scylaspora asperverruca sp. nov., Chelinospora textilis sp. nov., Hispanaediscus scabiosus sp. nov., and Hispanaediscus imbricatus sp. nov. A new genus, Vermiverruspora is created and the original description of Chelinospora Allen 1965 is resurrected. Six species of Chelinospora are reassigned to Vermiverruspora gen. nov. (C. paravermiculata Loboziak et al. 1988, C. vermiculata Chaloner & Streel 1968, C. Ivermiculata McGregor & Camfield 1976, C. retorrida Turnau 1986, C. rumneyi Burgess & Richardson 1995, C. vermoluta Burgess & Richardson 1995) and one species transferred to Stellatispora (pattersonii Wellman 1993). Four additional sporomorphs believed to be new, are not formally named because better preserved specimens are needed. The Arisaig Group (West Avalonia) is similar to sporomorphrich type sections in the Anglo‐Welsh Basin (East Avalonia). Four assemblage zones (avitus‐dilutus, brevicosta‐verrucatus, libycuspoecilomorphus, and tripapillatus‐spicula), and four assemblage sub‐zones (A. brevicosta, E. protophanus, C. obscura, and S. inframurinata var. inframurinata) have been recognized. Sporomorphs indicate that the contacts between the Lower and Upper Members of the McAdam Brook Formation and Green Member of the Moydart Formation may be one to two graptolite biozones older than previously reported. The Arisaig palynomorphs support the theory that a major radiation of vascular land plants occurred during the latter half of the Silurian Period. Llandovery and early Wenlock deposits at Arisaig contain only a few species of smooth walled spores and cryptospores. Sixteen trilete spore and fifteen cryptospore species appear between the Homerian and the late Prídolí. The tempo and composition of this diversification reflect evolutionary events observed elsewhere in the world.

Carbonate mud flows and other indicators of excess pore-fluid pressure in the Macumber Formation (Lower Carboniferous, Viséan) at Ingonish, Nova Scotia, Canada

The Ingonish area of northern Nova Scotia offers the most extensive exposure of the Macumber Formation, the basal carbonate unit of the Lower Carboniferous (Middle Visean) Windsor Group of Nova Scotia and New Brunswick. The area also shows tectonic-free sedimentary characteristics of this unit. The formation consists of two principal lithologic units, a basal, black, earthy, carbonaceous limestone normally about 0.5 m thick and a thinly stratified, peloidal dolomudstone up to 17.5 m thick. At Burke Head, the dolomudstone is cut by at least 25 massive tufa mounds, elongated in cross-section and intersecting their surrounding strata by rising northeastward at angles of 15 to 25 degrees. At east Ingonish Island the basal unit is anomalous in being both dolomitized and thicker (5 m); there, both units are cut by at least 20 smaller massive tufa mounds. The mounds at both localities formed over deep-water hydrothermal vents, i.e., marine hot springs; the fossils of abundant chemosynthetic tubeworms surround the lower mounds on east Ingonish Island. The Macumber Formation overlies Horton Group braided-stream facies sandstones, and presumably underlies nearby, thick gypsum deposits of the Windsor Group.

CURRENT STATUS OF THE INVASIVE GREEN ALGA CODIUM FRAGILE IN EASTERN CANADA

Ten years after the initial discovery of Codium fragile in eastern Canada on the Atlantic coast of Nova Scotia, C. fragile has extended its range considerably to northern Nova Scotia, southern New Brunswick and Prince Edward Island (P.E.I.) in the Gulf of St. Lawrence. In all principal areas C. fragile subsp. tomentosoides is present. In two regions of Prince Edward Island, Codium is becoming extremely abundant, and is known by local fishers as the “oyster thief”. A potential second taxon of Codium was collected in 1999 at three sites in Malpeque Bay where it is locally abundant. These plants are distinguished from C. fragile subsp. tomentosoides by their smaller frond size, flatter utricle tops, smaller mucrons, and smaller gametangia. Principal component analysis distinguishes plants of the two types. The abundance of C. fragile on both hard bottom and soft bottom substrata suggests that it will become the dominant alga in many subtidal algal communities in eastern Canada.

Geochemistry of the Namurian Lismore Formation, northern mainland Nova Scotia: sedimentation and tectonic activity along the southern flank of the Maritimes Basin

Geochemical and isotopic data from the clastic rocks of the Namurian Lismore Formation in mainland Nova Scotia identify key episodes of tectonic activity during the development of the Maritimes Basin in Atlantic Canada. The Lismore Formation forms part of the Mabou Group and is an upward-coarsening 2500 m thick fluvial sequence deposited in the Merigomish sub-basin along the southern flank of the Maritimes Basin. Based on stratigraphic evidence, the Lismore Formation can be divided into upper and lower members which reflect variations in depositional environment and paleoclimate. The geochemical and isotopic data may also be subdivided into two groupings that primarily reflect varying contributions from accessory phases, clay minerals, or rock fragments. This subdivision occurs 115 m above the base of the upper member. The data from the lower grouping (group A) show an important contribution from underlying Silurian rocks, with a relatively minor contribution from Late Devonian granitoid rocks from the adjacent Cobequid Highlands and possibly metasedimentary rocks from the Meguma Terrane to the south. The data from the upper grouping (group B) reveal a more important contribution from the Cobequid Highlands granitoid rocks. This variation in geochemistry is thought to constrain the age of renewed motion and uplift along the faults along the southern flank of the Maritimes Basin and, more generally, suggests that geochemical and isotopic data of continental clastic rocks may help constrain the age of tectonic events that influence deposition of basin-fill rocks.

Displacement transfer and forced folding in the Maritimes basin of Nova Scotia, eastern Canada

Abstract Field and seismic data in northern Nova Scotia, eastern Canada, demonstrate that displacement transfer from steep basement faulting to bedding-parallel detachment is necessary in the development of forced folds. Lateral translation of the strata above horsted and down-dropped blocks generates a monoclinal structure which, as the faults are kinematically linked, evolves in a manner similar to fault-bend folds in thrust-and-fold belts. In the case of partial transfer of displacement a breached drape syncline is developed. The breached syncline is characterized by steep upturned beds against the fault that truncates them. In the Nova Scotia example the detachment horizon is located at the base of a Visean evaporitic sequence, and is exposed in the study area showing shearing structures within the evaporites. Brittle fault rock types (gouge and cataclasite) and meso- to microstructures were formed, including stretching lineation, principal schistosity plane and secondary shear planes, as well as intrafolial to upright asymmetrical folds. The regionally extensive weak evaporitic layer was remarkably effective in transferring displacement between the two faults, with mechanical decoupling of the strata above the evaporitic detachment being observed in the horsted block 70 km away from the steep basement fault. Moreover, displacement was also transferred as much as 40 km onto the down-dropped block at the frontal part of the system.