Canadian Arctic–Beaufort Sea Rifted Margin Tectono-Sedimentary Element, SE Canada Basin

Peer reviewedPostprin

Early Cretaceous vegetation and climate change at high latitude: Palynological evidence from Isachsen Formation, Arctic Canada

Quantitative palynology of the marginal marine and deltaic-fluvial Isachsen Formation of the Sverdrup Basin, Canadian Arctic, provides insight into high latitude climate during much of the Early Cretaceous (Valanginian to early Aptian). Detrended Correspondence Analysis of main pollen and spore taxa is used to derive three ecological groupings influenced by moisture and disturbance based on the botanical affinities of palynomorphs: 1) a mixed coniferous assemblage containing both lowland and upland components; 2) a conifer-filicopsid community that likely grew in dynamic lowland habitats; and, 3) a mature dry lowland community composed of Cheirolepidiaceans. Stratigraphic changes in the relative abundance of pollen and spore taxa reflect climate variability in this polar region during the ~20 Mya history of the Isachsen Formation. The late Valanginian was relatively cool and moist and promoted lowland conifer-filicopsid communities. Warming in the Hauterivian resulted in the expansion coniferous communities in well-drained or arid hinterlands. A return to relatively cool and moist conditions in the Barremian resulted in the expansion of mixed lowland communities. This work demonstrates the utility of a multivariate statistical approach to palynology to provide insight into the composition and dynamics of ecosystems and climate of high latitude regions during the Early Cretaceous

The Middle-upper Devonian clastic wedge of the Franklinian geosyncline

Bibliography: p. 259-274.Middle - Upper Devonian elastic strata in the Canadian Arctic Islands are present over an area of about 200,000 sq km (75,000 sq miles) and are up to 5000 m (16,000 1) thick. The strata comprise a elastic wedge which was deposited in the Franklinian geosyncline prior to Late Devonian - Early Mississippian deformation. The elastic wedge is divided into eleven formations, and six facies are recognized within the strata. The formations and their facies content are: Blackley (submarine fan); Cape de Bray (marine slope); Weatherall (deltaic-marine shelf); Bird Fiord (open marine shelf and deltaic-marine shelf); Strathcona Fiord (meandering stream); Hecla Bay (braided stream); Fram (meandering stream); Hell Gate {braided stream); Nordstrand Point (meandering stream); Beverley Inlet (meandering stream); and Parry Islands (braided stream, meandering stream and deltaic-marine shelf). Mineralogy, facies distributions, paleocurrent patterns and regional geology all indicate that the source areas of the elastic strata lay to the north and east, and included the Caledonian and Pearya Mountain systems and Precambrian Shield of Greenland. Chert and rock fragments characterize detritus from the Pearya Mountains whereas detritus from the Caledonian Mountains and Precambrian Shield is characterized by a high percentage of monocrystalline quartz. Compositional variations within the elastic wedge indicate that the Pearya Mountains progressively supplied a higher proportion of the detritus throughout wedge development. Paleolatitude estimations, lithologies, fossils and clay minerailogy imply that the elastic wedge was deposited under humid tropical climatic conditions. Lithologic variations in fluvial strata suggest that the climate fluctuated between savanna and very humid. Clastic deposition commenced in the extreme northeast in Eifelian time, and a coastal plain prograded south and west until it covered almost the entire Arctic Islands area by Middle Frasnian. During progradation, submarine fan and marine slope deposits infilled deep basins in the northwest. In Late Frasnian the entire area was uplifted and subjected to erosion. The area was transgressed in latest Frasnian, and a marine shelf was widespread by Early Famennian. In latest Devonian or Early Mississippian the elastic wedge was uplifted and folded to form a "foothills" belt encircling the southwestern termination of the Pearya Mountains. Sandstone units of delta front, beach and distributary channel origin within the Weatherall and Bird Fiord Fms are rated as having the highest potential for petroleum accumulations. The strata may have uranium potential but the meager data, presently available in this regard, are not encouraging

A Late devonian reef tract on northeastern Banks Island, N.W.T.

Bibliography: p. 116-118.The exposed Upper Devonian succession on northeastern Banks Island, N.W.T. is 3700 feet thick and has been correlated with the Griper Bay Formation. It consists mainly of terrigenous elastic rocks which were deposited in a marine shelf to coastal complex environment. The source area was located to the west. The age of the exposed section ranges from the base of the Frasnian to the Middle Famennian. Devonian strata have been moderately deformed,and north-south trending folds and normal faults are present. Deformation occurred during the Mississippian,and the structures were reactivated in the Tertiary. A 200 foot carbonate unit occurs in the middle of the succession . It has been herein named the Mercy Bay Member and is of Middle Frasnian age. It contains many organic buildups and represents a Devonian reef tract. The reef tract was located on the western shelf of an exogeosyncline which extended along the margin of North America between the stable craton and a western tectonic highland. The main facies changes in the Mercy Bay Member occur in an east-west direction. The organic buildups in the eastern part of the study area, which is the seaward edge of the reef tract, are narrow, linear bioherms which trend north-south. They are encased in younger terrigenous elastic rocks. To the west, the organic buildups, which are biohermal in the lower part and biostromal in the upper part, are more numerous. The lower bioherms trend east-west, and the inter-biohermal strata, which consist of dark, fine -grained, argillaceous limestones, are penecontemporaneous. The organic buildups on the western edge of the outcrop area are larger and are biohermal. The shoreward edge of the reef tract is not exposed. The lower portion of all the organic buildups is composed of corals and tabular stromatoporoids which built biogenetic banks in the quiet and intermediate energy zones. These energy zones are postulated to have been below 30 feet of water depth. The upper portion is composed of massive stromatoporoids which built rigid reefs in the high energy zone (above 30 feet). Successive sea level rises allowed the reefs to grow upward. The cessation of reef growth was caused by a rise in sea level and an influx of terrigenous sediment. The Griper Bay Formation appears to be a potential producer of hydrocarbons. The main potential reservoirs are the high energy coastal complex sandstones and possibly the organic buildups of the Mercy Bay Member

Hygiene hypothesis: innate immunity, malaria and multiple sclerosis

The establishment of new hygienic conditions plays a role in the appearance of autoimmunity in ‘‘westernalised’’ countries. Consistently, but still unconvincingly, several epidemiological and immunogenetic evidences link the disappearance of malaria with the increase of multiple sclerosis (MS) in Sardinia, insular Italy. To this purpose, we have made an attempt to build a relationship between malaria disappearance and MS under the light of the hygiene hypothesis. This relationship has taken into account the MS frequency increase soon after malaria eradication in Sardinia, the present malaria endemism in Africa, the innate immune system activity here represented by Chitotriosidase (Chit), an hydrolytic enzyme produced by macrophages, and an unproductive polymorphism of Chit gene (CHIT1) as a measure of the genetic weight of Plasmodium-related immunity in these populations. Data were derived from both experimental results specifically designed for this study and other data obtained from the available literature. The experimental and the hystorical–epidemiological findings concur to indicate that whilst in Africa CHIT1 mutation is rare and MS incidence is very low due to unmodified parasitic influence and hygienic conditions, in Sardinia a relationships between CHIT1 mutation, plasma Chit activity and MS prevalence rate is detected, even to a higher extent compared to Sicily, area at former lower rate of malaria endemy. Upon such a basis, we have found convincing argumentations that, at least in part, MS has increased over the last four decades in Sardinia also because of the eradication of malaria, 50 years ago. This infectious disease that run for centuries in Sardinia, besides well documented enzyme deficiencies and red cell pathologies, have left an abnormal macrophage reactivity against Plasmodium falciparum. As a result, some Sardinian individuals secrete abnormally high levels of mediators of the innate immunity, relics of former protective anti-malaria infection, in response to new environmental factors. Therefore, MS, an immune-conditioned pathology of the central nervous system has been subject to an unexplained epidemiological increase in the last few decades in Sardinia because cells of the innate immune system, immuno-genetically selected over the centuries in response to widespread P. falciparum malaria, have kept the tendency to over-respond to triggering factors even after the disappearance of malaria. This hypothesis may have an influence in re-directing clinicians toward a innate immunity-based rather than an antigen specific-based new MS therapies

Whose Farm to Whose Table? The Challenge of Enhancing Access to Local Food

This is a panel discussion moderated by Rona Roberts

Aptian to Santonian Foraminiferal Biostratigraphy and Paleoenvironmental Change in the Sverdrup Basin as Revealed at Glacier Fiord, Axel Heiberg Island, Canadian Arctic Archipelago

Exceptional exposures of a High Arctic Cretaceous sedimentary record were studied at Glacier Fiord, Axel Heiberg Island. The succession reveals a complex Aptian to Santonian paleoenvironmental history of the Sverdrup Basin that documents several global events. Foraminiferal faunas in combination with rare macrofossil occurrences permit the distinction of nine zones that facilitate biostratigraphic correlations to other High Arctic locales, the Beaufort Mackenzie Basin and the Western Interior Sea. The depositional environment as exposed in the Christopher, Hassel, Bastion Ridge and Kanguk formations changed frequently from a shelf to a shoreface setting. Most sequence boundaries appear to be conformable where shoaling reached lower shoreface levels without subaerial exposure. An exception is the top of the Hassel Formation, correlated here with the Albian/Cenomanian disconformity where a paleosol developed on top of an upper shoreface environment. Transgressive/regressive sequences at Glacier Fiord correspond well with globally recognized transgressive/regressive mega cycles. The lower Christopher Formation shows frequent glendonite beds that attest to the Late Aptian/Early Albian cooling event. The required alkaline conditions for glendonites preserved the only calcareous faunule in the succession. Siliceous microplankton are assumed to be taphonomically removed due to deep burial. The Middle to Late Albian oceanic shelf conditions appeared to be most hospitable and foraminifera grew large tests. In the early Cenomanian and lower Bastion Ridge Formation, benthic species disappear. This sudden loss is interpreted as a consequence of nearby volcanic activity related to the Strand Fiord Formation and basin restriction. This is followed by a period of increased preservation of organic carbon and a distinct increase in marine productivity marking the OAE 2 in the Polar Sea straddling the Cenomanian/Turonian boundary. This interval is expressed in a platy shale, devoid of microbioturbation, but characterized with a repopulation event where the low oxygen tolerant genus Trochammina is the dominant component. The Upper Turonian to Santonian interval of the Kanguk Formation reflects shelf conditions that supported mostly rich benthic assemblages, but have at times minute tests as a response to oxygen depletion