Somerset Island Research Articles

The Discovery of Diamonds in Siberia and Other Northern Regions: Explorational, Historical, and Personal Notes

Only four known diamond locations are near and north of the Arctic Circle. What is believed to be the oldest diamond find in this region was made in the gravels of the Pasvik River on the U.S.S.R.-Finland-Norway border. This was followed by the discovery of the northern fields of the Yakutian diamondiferous province in the U.S.S.R. Somerset Island in the Canadian Arctic Archipelago and southwestern Greenland conclude this short list. Geographically close to the Arctic but south of the Arctic Circle are the diamond locations on the shore of the Beloye More or White Sea and in the Timan Range (U.S.S.R.), western and eastern Alaska (U.S.A.), and in the Mackenzie Mountains (Canada). Farther south and partly in the Subarctic are locations in the Ural Mountains and Yakutia (U.S.S.R.), as well as in Labrador and Saskatchewan (Canada). While the discoveries in Canada and Greenland belong to our times, the history of the others is hidden in ancient records. For the Yakutian fields, which are of major economic importance and among the world leaders in the production of gem quality diamonds, an ancient reference dating back to 1375 is presented here for the first time.

A bangiophyte red alga from the Proterozoic of arctic Canada.

Silicified peritidal carbonate rocks of the 1250- to 750-million-year-old Hunting Formation, Somerset Island, arctic Canada, contain fossils of well-preserved bangiophyte red algae. Morphological details, especially the presence of multiseriate filaments composed of radially arranged wedge-shaped cells derived by longitudinal divisions from disc-shaped cells in uniseriate filaments, indicate that the fossils are related to extant species in the genus Bangia. Such taxonomic resolution distinguishes these fossils from other pre-Ediacaran eukaryotes and contributes to growing evidence that multicellular algae diversified well before the Ediacaran radiation of large animals.

Predation of Belugas and Narwhals by Polar Bears in Nearshore Areas of the Canadian High Arctic

On 18 August 1988 we found four narwhals and two dead belugas stranded on a low beach at Creswell Bay, Somerset Island. All of the narwhals and two of the belugas had been attacked and partially eaten by polar bears. At Cunningham Inlet, where belugas concentrate in large numbers, we have noted ten strandings over the period 1980-88, without bear predation on these occasions. One bear, hunting from an ice floe in deep water at Cunningham Inlet, killed two sub-adult belugas in July 1985. Belugas seem to exhibit curiosity towards swimming polar bears that might serve to drive bears out of the area and reduce the risk of predation. The potential large summer food resource for bears represented by odontocete whales in the High Arctic Archipelago seems to be underutilized. The timing and location of beluga concentrations are known and dates of probable strandings are somewhat predictable, which might allow us to assess the extent of bear predation on whales in the future.

'Round Lord Mayor Bay with James Clark Ross: The Original Diary of 1830

During John Ross's arctic expedition of 1829-33 in search of a northwest passage, approximately 1000 km of new coastline was mapped. Included in these new coastlines was Lord Mayor Bay on eastern Boothia Peninsula, which was surveyed by Ross's nephew and second-in-command, James Clark Ross, in 1830. The results of the Lord Mayor Bay survey effectively ended any chance of there being a northwest passage south and east of Somerset Island or west of northern Foxe Basin and northwest Hudson Bay. Despite the obvious importance of James Clark Ross's survey, it was not included in John Ross's published narrative of the expedition. The original diary has recently been located and is reproduced here, together with accompanying sketches and observations and a discussion of the circumstances of the survey.

Note on the UPb perovskite method for dating kimberlites: Examples from the Wesselton and De Beers mines, South Africa, and Somerset Island, Canada

The previously reported UPb perovskite method of dating kimberlite has been substantially improved by obtaining high-purity perovskite concentrates using a combination of chemical, magnetic and hand-picking techniques. Reliable results are obtained from subhedral to euhedral perovskite, but not from anhedral perovskite commonly displaying atoll-like grain shapes. The latter may be weathered or may have been partially digested in the chemical treatment used in the initial concentration step. An age of 89 Ma was obtained from the Wesselton kimberlite and one of two De Beers Mine samples, while a second De Beers sample gave a younger age of ∼ 83 Ma. These ages are in agreement with previous age determinations by various other methods. The ThPb age for perovskite from De Beers Mines is 81 Ma. An age of ∼ 105 Ma for a Somerset Island kimberlite is in agreement with a RbSr errorchron age of ∼ 100 Ma for micas from a second Somerset Island occurrence, but a perovskite age of 40 Ma for a third locality is not realistic. Fresh kimberlitic perovskite has U and Pb concentrations of ∼ 150 and 15 ppm, respectively. Th concentrations fresh perovskite are of the order of 1000 ppm, though this is based on only one sample from the De Beers Mine. 87Sr/ 86Sr ratios and presumably 143Nd/ 144Nd ratios are easily obtained from groundmass perovskites, and reflect the initial Sr and Nd isotopic compositions of kimberlite at the time of emplacement.

Till behavior and its relationship to active-layer hydrology, District of Keewatin, Northwest Territories

Well-graded tills are a common surficial material over much of the Canadian Arctic from northern Manitoba to Somerset Island. The compactibility and bearing strength of these tills when thawed appear to be controlled by groundwater flow in the active layer. Water seeping from bedrock outcrops flanked by till enters the till active layer and flows via macropores formed as ice lenses thaw. This flow appears to retard consolidation of the till. Slopes having no seepage source consolidate more rapidly. This seepage maintains the till in a state highly susceptible to liquefaction and would yield material with a moisture–density condition unsuitable for construction use. Key words: till, surficial, compactibility, bearing capacity, groundwater, seepage, freeze–thaw, liquefaction.

The role of contemporaneous faulting on Late Silurian sedimentation in the eastern M'Clintock Basin, Prince of Wales Island, Arctic Canada

During the Late Silurian, the eastern margin of the M'Clintock Basin was the site of slow sedimentation on a relatively stable carbonate platform. It is apparent, however, that contemporaneous (syndepositional) faults segmented this basin into several quasi-independent subbasins during deposition of the Cape Storm, Douro, and Somerset Island formations. Differential subsidence of these subbasins played a major role in controlling sedimentation patterns and stratigraphie thickness. These subbasins may have been sustained into the Early Devonian, as is evident from the facies of the overlying Peel Sound Formation. The east–west orientated, reactivated basement faults bounding the subbasins served as zones of weakness during the development of the Cornwall is Fold Belt and are evident in the present-day outcrop.

A New Heterostracan from the Upper Silurian of Northwest Territories, Canada

ABSTRACT The new genus and species Alainaspis platyrhina from the Silurian of Prince of Wales and Somerset Islands, Northwest Territories, Canada is a large cyathaspidid of the subfamily Poraspidinae with distinctive proportions of probable adaptive significance. It is most closely related to Boothiaspis, previously described as an amphiaspid, but here reassigned to the Poraspidinae. The distribution of this genus helps to provide local correlation between the lower member of the Peel Sound Formation and the Somerset Island Formation on Prince of Wales and Somerset Islands. Associated invertebrates and vertebrates indicate a late Ludlovian to Pridolian age for the fauna.

Effects of Snow and Ice on Waterfowl Distribution in the Central Canadian Arctic Islands

Aerial surveys were conducted in 1974 and 1975 to determine distribution and abundance of waterfowl along the coasts of Somerset, Cornwallis, Little Cornwallis, and Byam Martin islands, Boothia Peninsula, as well as parts of Prince of Wales, Devon, Bathurst, and Melville islands. Waterfowl nested normally in 1975 but were prevented from doing so in 1974 by a late thaw. In 1974, but not in 1975, Barrow Strait was ice free by 1 June. Densities of most species were lower in spring 1975 than in 1974, when inhospitable conditions inland forced the birds to concentrate in coastal areas. In late summer Brant (Branta bernicla) and Oldsquaw (Clangula hyemalis) were more numerous in 1975 than in 1974; Brant left the central High Arctic in midsummer 1974, but the reason for the smaller number of Oldsquaw is not evident. Both Snow Geese (Chen caerulescens) and eiders (Somateria spp.) were more abundant in late summer 1974 than in 1975. Many Snow Geese moved to southeastern Somerset Island and adjacent waters to moult in 1974. In 1975 many eiders and Snow Geese remained at inland locations with their broods. Queens Channel, northern Somerset Island and Bellot Strait were particularly important to waterfowl, irrespective of spring phenology. Melville and Byam Martin islands were used by Brant, and Canada Geese (Branta canadensis) occurred mainly on the Boothia Peninsula. Snow Geese were abundant in both years in southeastern Somerset Island, particularly near Creswell Bay, where both breeding and moulting occurred. Coastal waters of Barrow Strait, Prince Regent Inlet and the Gulf of Boothia were heavily used by Oldsquaw in spring and summer, and Crooked Lake, Prince of Wales Island, was used by many moulting Oldsquaw in both years. Common Eiders (S. mollissima) occurred principally in Queens Channel, Barrow Strait and near Bellot Strait; King Eiders (S. spectabilis) also concentrated in the same areas but were more widely distributed throughout the study area.Key words: Arctic Islands, N.W.T., waterfowl distribution, nonbreeding, aerial surveys, Brant, snow Geese, Oldsquaw, eiders

Cultural and Natural Formation Processes of a Historic Inuit Snow Dwelling Site, Somerset Island, Arctic Canada

Analysis of the remains of a historic Inuit winter site, in conjunction with information supplied by one of the original inhabitants, demonstrates that despite post-occupational disturbance in the form of snow melt and associated downslope movement, the original internal site structure was maintained. Specific activity loci are identified for two snow houses, one occupied during early winter and the other during late winter. Changes in artifact and faunal element characteristics associated with the two dwellings are shown to reflect adjustments in various hunting and domestic activities from early to late winter.

Upper Silurian lithistid sponge reefs on Somerset Island, Arctic Canada

ABSTRACTThe Upper Ludlow Douro Formation contains the first reported Silurian sponge reefs. These relatively small (5–35 m diameter), mound‐shaped structures contain, on average, 35% lithistid demosponges. Reefs are surrounded by irregular haloes of crinoid debris; abundance and diversity of all fossil groups decreases away from the reefs. Each reef is underlain by a lens of crinoid wackestone to grainstone rich in crinoid holdfasts; trepostomate bryozoans, solenoporacean algae and rhynchonellid brachiopods are locally common. The bulk of each reef consists of lime mudstone with abundant lithistid sponges. This is capped by a thin layer of wackestone with abundant tabulate and rugose corals and fewer lithistid sponges, calcareous algae, trepostomate bryozoans and stromatoporoids. This zonation, in which a sponge colonization community was replaced by a coral diversification community, is similar to that reported from some Middle Ordovician, Upper Jurassic and Holocene sponge reefs.The Douro sponge reefs were relatively low structures, with about 3 m maximum topographic relief. They grew on a broad carbonate platform, probably in warm, tranquil, turbid waters of normal or near‐normal marine salinity. Periodic influxes of terrigenous mud adversely affected reef size, and caused biotic changes. Some of the reef lime mud was derived from non‐reef sources, but significant quantities were also produced on the reefs. Reefs underwent synsedimentary lithification, bioerosion and minor storm erosion. Fabrics and compositions of sparry calcite in cavities record three generations of meteoric cementation. Originally siliceous spicules of the lithistid sponges were dissolved and the moulds later filled with sparry calcite. Early dissolution of siliceous spicules is common in reef environments, and may have caused fossil sponges to be under‐represented in ancient reefs.

Trace Fossils in Siluro-Devonian Tidal Flat to Distal Basin Slope Carbonates of Arctic Canada: ABSTRACT

Upper Silurian and Lower Devonian carbonates of Somerset, Griffith, Cornwallis, and Devon Islands (Arctic Canada) were deposited under conditions which ranged from tidal flat in the south to basin slope in the north. Trace fossils occur commonly in this succession. Planolites, Palaeophycos, Chondrites, and Skolithos are ubiquitous throughout the sequence. Seven commonly occurring ichnogenera exhibit restricted environmental conditions: Polarichnus is confined to tidal flat deposits, Zoophycos and Pilichnia are most common in deep subtidal shelf and upper basin slope deposits, and Phycodes, Lockeia, Taenidium, and Cruziana occur predominantly in basin slope deposits. Seven other ichnogenera, Arenicolites, Arthraria, Cochlichnus, cf. Furculosus, Helicodromites, Teichichnus, and cf. Thalassinoides, occur only very rarely. Trace fossil assemblages of the tidal flat and subtidal shelf carbonates are broadly similar to the Skolithos and Cruziana ichnofacies reported from environmentally equivalent siliciclastic deposits. Similarly, the assemblage of the deep subtidal-upper basin slope carbonates resembles the environmentally equivalent Zoophycos ichnofacies. In contrast, the assemblage of the basin slope carbonates comprises abundant resting and feeding traces (Cruziana ichnofacies) whereas assemblages of siliciclastic slope deposits are dominated by complex grazing traces and graphoglyptids (Nereites ichnofacies). The relative scarcity of arthropod traces throughout this carbonate sequence probably reflects diagenetic alternation of bedding surfaces. End_of_Article - Last_Page 524------------

Stochastic analysis of complex lithological successions

It is difficult to develop stochastic models for complex lithological sequences that are typically associated with intertidal-supratidal depositional environments. A sequence from the Upper Silurian Leopold Formation on eastern Somerset Island is used to demonstrate that a combination of cluster analysis, Markov Chain analysis, and substitutability analysis can give considerable insight into the nature of such complex successions. The high variability of this sequence was created by a combination of (a) variation in the depositional environment, (b) variation in the degree of dolomitization, (c) variation in the clastic influx, (d) random highenergy (possibly storm associated events) and (e) random breaks in the succession of depositional environments.

Event Correlation in Upper Silurian Rocks of Somerset Island, Canadian Arctic

Recurring sedimentary events can sometimes be used for time correlation in sequences where biostratigraphic control is insufficient. On Somerset Island in the Canadian Arctic, the Upper Silurian Leopold Formation, a thick heterogeneous, sparsely fossiliferous carbonate sequence, largely of intertidal origin, displays broad fluctuations in siliciclastic content. The peaks of detrital content can be correlated widely and are considered to be time-equivalent. A field correlation using lithologic markers accentuated by weathering relief agrees with the proposed event correlation. Preliminary studies of fossil ostracoderms suggest that a complementary faunal succession is also present. According to the event correlation, previously defined lithostratigraphic boundaries are dia hronous, some markedly so.

Atrypoidea zonation of the Upper Silurian Read Bay Formation of Somerset and Cornwallis Islands, Arctic Canada

Species of the brachiopod genus Atrypoidea have a distinct distribution in carbonate rocks of the late Silurian Read Bay Formation of Arctic Canada. Atrypoidea phoca occurs in the basal part of the formation and this species is succeeded by Atrypoidea foxi forma B at higher levels. The ranges of the two species overlap, defining a third useful zone. Locally, as in the Pressure Point area of northwestern Somerset Island, Atrypoidea foxi forma B is succeeded by Atrypoidea foxi forma A. Atrypoidea foxi forma A is generally restricted to carbonates with a low content of detrital material and has a significantly larger shell than Atrypoidea foxi forma B. A higher zone is defined by Atrypoidea erebus which occurs in the basal part of the Somerset Island Formation on Somerset Island and in the basal part of member C of the Read Bay Formation at Goodsir Creek on Cornwallis Island. At the latter locality, Atrypoidea foxi forma A is found with Atrypoidea erebus, thereby demonstrating their overlapping ranges.The overlapping ranges of Atrypoidea phoca and Atrypoidea foxi forma B occur in the middle to late Ludlovian ploeckensis–siluricus conodont zones. On Somerset Island, Atrypoidea foxi forma B and Atrypoidea foxi forma A range through the ploeckensis–siluricus conodont zone. Atrypoidea erebus occurs in late Ludlovian and (or) early Pridolian strata.

The geomorphology and origin of Point Pelee, southwestern Ontario: Discussion

CALLAHAN, W. H. 1978. Cornwallis Lead-Zinc District; hlississippi Valley-type deposits controlled by stratigraphy and tectonics: Discussion. Canadian Jo~~rna l of Earth Sciences, 15, pp. 459-460. 1979. Cornwallis 1,ead-Zinc District; Mississippi Valley-type deposits controllect by stratigraphy and tectonics: Discussion 11. Canadian Journal of I:,arth Sciences, 16, pp. 614-615. KERR. J. Wh4. 1975. Cape Storm Formation-a new Silurian unit in the Canadian Arctic. Bulletin of Canadian Pelroleunl Cieology, 23, pp. 69-83. 1977~1. Clornwallis Fold Belt and the mechanism of basement uplift. Canadian Journal of Earth Sciences, 14, pp. 1374-1401. 1077b. Cornwallis 1.-cad-Zinc Llistrict; hlis\issippi Valley-type deposits controlled by stratigraphy and tectonics. Canadian Journal of Earth Sciences, 14, pp. 1402-1426. -1978. Cornwallis Lead-Zinc Ilistrict; Mississippi Valley-type deposits controlled by stratigraphy and tectonics: Reply. Car~adian Journal of Earth Sciences, 15, p. 460. MIAI I. . A. D., itnd KCKR. J. WM. In press. Cambrian to Upper Silurian stratigraphy, Somerset Island and northeastern Roothia Peninsula, District of Franklin, N.W.'T. Geological Sul-vey of Canada Bulletin. ' I ' ~ o n s r . ~ r ~ s s o ~ , R. 1958. Cornwallis and Little Cornwallis Islands, District of Franklin, N~I-thwest 'I'erritories. Geological Survey of Canada, hlemoir 294.

Upper Silurian stromatoporoids from Somerset Island, Arctic Canada

Plexodictyon katriense Nestor, P. heclae n. sp., Diplostroma sp., Actinostroma furyi n. sp., Actinodictyon netsiliki n. sp., and Vicinostachyodes sokolovi (Riabinin) occur in Upper Silurian (middle to late Ludlovian) strata near Creswell Bay, Somerset Island. Faunal and sedimentological evidence suggests the stromatoporoids inhabited predominantly shallow, high energy, near-shore environments.

Paleomagnetism and age of the Aston dykes and Savage Point sills of the Boothia Uplift, Canada

Oriented samples (107) have been drilled for paleomagnetic studies from diabase sills and dykes on either side of the Boothia Uplift, Canada. Six sites at Savage Point are in sills which intrude the Aston Formation; three, at Whitehead Point, north of Savage Point on the east coast of Prince of Wales Island, are in sills which also intrude these strata. Six sites in the Aston Bay area of Somerset Island are in dykes and a sill which cut the Aston Formation; the former also intrude the Hunting Formation. No meaningful results were obtained from the Whitehead Point samples. Paleomagnetic measurements on the Savage Point samples, together with new K–Ar data, strongly suggest these sills belong to the Mackenzie igneous episode (ca. 1240 Ma). The sill in the Aston Bay area apparently belongs to this episode too, whereas most of the dykes are Franklin dykes (ca. 675 Ma). One large dyke was possibly emplaced in Tertiary times. Thus the Aston Formation is older than 1240 Ma and the Hunting Formation is bracketed between 1240 and 675 Ma.

The Siluro-Devonian clastic wedge of Somerset Island, Arctic Canada, and some regional paleogeographic implications

Upper Silurian and Lower Devonian rocks on Somerset Island were derived from Boothia Uplift, a linear tectonic belt that underwent a pronounced period of positive movement commencing in the Pridolian. The lower part of the clastic wedge is a succession of predominantly intertidal to supratidal dolomite and siltstone 150–400 m thick (Somerset Island Formation). Markov analysis documents the presence of tidal cycles in these rocks. The succession changes eastward, away from the uplift, into subtidal marine limestone indistinguishable from that of the underlying Read Bay Formation. The Somerset Island Formation grades vertically and laterally westward into alluvial deposits of the Peel Sound Formation, which consists of red sandstoné of braided river and possibly eolian origin, and two fanglomerate members. A variety of fluvial fining-upward and thinning-upward cycle types has been documented by Markov analysis of a lower sand member of the formation. The Peel Sound reaches a maximum thickness of 600 m in northern Somerset Island. Paleocurrent analysis of crossbedding indicates eastward transport directions in the fluvial rocks, except for cosets of very large scale crossbeds (up to 6 m thick) in the northwestern part of the island, which indicate northwesterly flow. The large sets are interpreted as the deposits of eolian dunes, or of sand waves in a large trunk river which carried clastic detritus northward, parallel to Boothia Uplift. The Peel Sound Formation and its lateral facies equivalents on Prince of Wales Island, west of Boothia Uplift, contain coarser conglomerates and a higher sandstone/carbonate ratio, indicating deposition under higher energy conditions than are thought to have prevailed in Somerset Island. Relief may have been greater and depositional slope steeper in the west, an asymmetry in Boothia Uplift that is reflected in the present-day structural style of a narrow zone of tilting and reverse faulting in the west, and a broad zone of gentle folding and normal faulting in the east. The similarity in structural and stratigraphic asymmetry indicates a genetic link, which is further suggested by the presence of syndepositional folds and unconformities at a few localities within the clastic wedge. An estimate of the volume of sediment removed from Boothia Uplift indicates that approximately one third can be accounted for in the present clastic wedge on either side of the Uplift. Either the Lower Paleozoic formations were attenuated over the Uplift, or rivers such as the hypothetical trunk river were effective in the dispersal of material beyond the region of the clastic wedge.

Predaceous nematodes of the family Mononchidae from the Mackenzie and Porcupine river systems and Somerset Island, N.W.T., Canada

Paramononchus arcticus n.gen., n.sp., Coomansus fletcherensis n.sp., and Mononchus superbus n.sp. from the Mackenzie and Porcupine river systems and Somerset Island are described and illustrated. Paramononchus n.gen. is closest to Mononchus Bastian, differing in having the dorsal tooth opposed by a denticulated rib with two small basal teeth and a transverse rib at the level of the dorsal tooth. Other mononchids from the river and lake samples are described and illustrated including Coomansus gerlachei and Mononchus maduei which are reported for the first time in Canada.A new genus Parahadronchus is defined with Parahadronchus adamanicus (Jairajpuri, 1969) n.comb. as its type species, and generic diagnoses and a key to the 23 recognized genera of Mononchidae are included.