bluuebunny/crossref_metadata_2025 huggingface dataset:
Holocene vegetation and climatic history of Prince Edward Island, Canada
Authors: Anderson T. W.
Published: April 2011

The vegetation and climate of the Holocene of Prince Edward Island are reconstructed from pollen analysis of four Sphagnum peat bogs, Portage and East Bideford Bogs in the west and Mermaid and East Baltic Bogs in the east. The discussion is based largely on percentage data supported by pollen influx estimates.The earliest recognizable vegetation was tundra-like with nonarboreal birch, willow, Artemisia, and upland grasses and sedges. The vegetation changed remarkably within a short period, from tundra at 10 000 years BP, to forest–tundra (spruce – nonarboreal birch association) between 10 000 and 8000 years ago, to pine at or shortly after 8000 years ago. Hemlock arrived 7000 years ago and dominated along with white pine from about 6500–4500 years BP. Beech came in about 3400 years ago and formed part of a hemlock–beech–birch association up until modern times. Sharp increases in weeds and grasses and declines in hemlock, birch, and beech denote European settlement approximately 100–150 years ago.A gradual warming tend is inferred for the period prior to about 8000 years BP, but rapid climatic improvement took place shortly after 8000 years ago corresponding with the pollen transition from spruce to pine. Maximum temperatures (close to 8.5 °C) were reached approximately 4000 years ago when the mean annual temperature may have been almost 2.5 °C warmer than present. Deterioration of the climate occurred at approximately 3000 and 1500 years ago, coinciding with increases in spruce, Ericaceae, and Sphagnum, and a decrease in pine.
A modified norm calculation
Authors: Currie K. L.
Published: April 2011

The CIPW norm gives results which closely resemble the mode for basalt and many other quartz-saturated igneous rocks, but which depart widely from the mode for alkaline and peralkaline assemblages. A modified norm, deleting halite, thenardite, sodium metasilicate, potassium metasilicate, sodium carbonate, and larnite, and substituting sodalite, enigmatite, eudialyte, riebeckite, andradite, and Ca-tschermaks molecule (CaAl2SiO6), gives a good representation of most alkaline and peralkaline igneous rocks while giving results identical to the CIPW system for common rocks. Estimates of silica saturation, differentiation indices, and disposition of alkalies are substantially improved.
The paleomagnetism of the Great Slave Supergroup: the Akaitcho River Formation
Authors: Evans M. E. , Hoye G. S. , Bingham D. K.
Published: April 2011

Results are reported from 120 oriented samples collected from 40 stratigraphic horizons spanning the Akaitcho River Formation of the Great Slave Supergroup. Thermal demagnetization experiments reveal the presence of multiphase remanence. Difference vectors indicate that the lower blocking temperatures carry a magnetic component attributable to the present field. The remanence remaining above 500–600 °C defines two polarity groups, but the two groups are not exactly antiparallel. This is interpreted in terms of a previously recognised widespread magnetic overprint acquired during uplift and cooling in the Coronation Geosyncline. A compilation of appropriate overprint data from the Great Slave Supergroup yields a mean direction of D = 152°, I = +64 °(N = 75 sites, k = 30, α95 = 3°), with a corresponding pole at 91°W, 21°N (K = 14, A95 = 5°). A statistical procedure is employed to remove this overprint and obtain a best estimate of the original magnetization, which corresponds to a paleomagnetic pole on the western limb of the Coronation loop (92°W, 4°S, N = 35 sites, K = 13, A95 = 7°).
Early Mesozoic diabase dikes of the Avalon Peninsula, Newfoundland: Petrochemistry, mineralogy, and origin
Authors: Papezik V. S. , Hodych J. P.
Published: April 2011

A narrow linear pattern of magnetic anomalies, trending in a northeasterly direction across the southeastern part of the Avalon Peninsula of Newfoundland, was interpreted earlier as a trace of a major diabase dike of possibly Triassic age, part of the early Mesozoic dike system of the Appalachians. Several isolated outcrops of diabase found recently by J. Hodych along the magnetic anomaly line over a distance of 70 km yield K–Ar isochron ages of 201 and 191 Ma, thus confirming the earlier interpretation.The Avalon diabase is a quartz-normative tholeiite, chemically similar to the 'high-Ti' Appalachian diabase; however, its MgO content is higher than normal for such rocks, approaching that of a rift-related ocean-floor basalt. The Avalon rocks consist of 45-50% plagioclase (An60–70), 40–45% magnesian augite (Ca38Mg52Fe10), 2–3% olivine (Fo78–82), and 3–4% Fe-Ti oxides. Alteration is of deuteric origin; there is no trace of albitization or low-grade metamorphism. The original titanomagnetite has been oxidized to very fine lamellar intergrowth of magnetite and ilmenite; mole fractions of Usp and Hm calculated from bulk analyses of the oxide minerals indicate an equilibration temperature of 970 ± 60 °C and oxygen fugacity (log10f(O2)) of −12.3 ± 1.The Avalon diabase comprises probably two or more dikes intruded into a fissure over 110 km long. These dikes extend the known system of early Mesozoic diabase dikes of the Appalachians by 800 km to the north-east, probably to the edge of the continental shelf.
Quaternary events on the Burin Peninsula, Newfoundland, and the islands of St. Pierre and Miquelon, France
Authors: Tucker C. M. , McCann S. B.
Published: April 2011

Morphogenetic mapping of surficial deposits and analysis of infrequent multiple-unit exposures of drift in the Burin Peninsula and on St. Pierre and Miquelon provide evidence of the following sequence of late Quaternary events in the south-central coastal region of Newfoundland. (1) Overall glaciation by Newfoundland-centred ice (pre-Wisconsinan or, possibly, Early Wisconsinan in age), represented by a few occurrences of weathered till. (2) Overall glaciation by Newfoundland-centred ice (Early Wisconsinan), widely represented throughout the peninsula. (3) Marine overlap in the southwest of the peninsula and on St. Pierre and Miquelon (Mid-Wisconsinan). (4) Partial glaciation by ice from an offshore source to the southeast (late Mid-Wisconsinan), represented by onshore-directed striae and a well-developed former ice-marginal position in the lower peninsula. (5) Limited glaciation by Newfoundland-centred ice of the northern part of the area (Late Wisconsinan); the former ice margin is a well-defined feature across the Gisborne basin and small separate ice caps existed along the central spine of the upper peninsula. In developing the chronology for these events, the occurrence of marine deposits, containing Foraminifera of proposed Mid-Wisconsinan age, between two till units at Dantzic Cove in the southwest of the Burin Peninsula is important.
Plate kinematics of the Denali fault system
Authors: Stout James H. , Chase Clement G.
Published: April 2011

Two segments of the Denali fault system, the McKinley strand west of the Delta River and the Dalton–Shakwak fault east of the Delta River, have nearly perfect small circle geometries. This geometry permits interpretation of the right-lateral slip along these faults in terms of rigid plate tectonics. Their poles of rotation are in the Gulf of Alaska at 59.63°N, 147.38°W and 50.38°N, 154.02°W respectively. A model in which there has been simultaneous motion on both faults since 38 Ma ago predicts a third fault at their juncture which must act as a plate boundary with northwesterly thrust motion in this time interval. The Broxson Gulch thrust, which extends from near the Susitna River to its termination at the Delta River, meets these requirements. Paleozoic and Mesozoic volcanics, as well as Oligocene or younger strata, are thrust beneath sillimanite schists along this fault, and major pre-Tertiary fold structures are truncated by it. Given the direction of tectonic transport on all three faults and a displacement of 38 km on the McKinley strand, the minimum displacements on the Broxson Gulch and the Denali (Dalton–Shakwak) faults in the last 38 Ma are approximately 54 and 90 km respectively. The previously correlated Maclaren and Ruby Range metamorphic belts, however, indicate 300–400 km offset since about 55 Ma ago. Our results require that about 300 km of this be taken up west of the Maclaren belt, either on the McKinley strand or on thrust segments similar to the Broxson Gulch, or both. Our results further indicate that the arcuate shape of these segments of the Denali fault system are intrinsic properties of the faults themselves and that oroclinal bending need not be invoked to explain them.
An Archean ultramafic turbidite from Lac Guyer, James Bay Area, Quebec, Canada
Authors: Stamatelopoulou-Seymour Karen , Francis Donald M.
Published: April 2011

A sedimentary rock of ultrabasic composition (MgO 28%, SiO2 48%) has been identified in an Archean volcanic sequence ranging from basaltic to peridotitic komatiite in composition, in the Lac Guyer greenstone belt, James Bay region of New Quebec. The ultramafic sedimentary rock is cyclically layered with an internal stratigraphy indicative of deposition from an aqueous turbidity current. Layers which are interpreted to correlate with the arenaceous A, B, and C divisions of turbidites are pyroxene-rich and display sedimentary features such as grading, parallel and cross-laminations, and climbing ripples. Foliated layers with higher normative olivine contents preserve loading and soft sediment deformation structures indicating a pelitic nature when deposited and are interpreted as Bouma E divisions. These features combined with a sympathetic variation of Al2O3 with normative olivine content in successive Bouma divisions suggest that a Mg-chlorite with subordinate serpentine rather than olivine was present, together with pyroxenes and opaques, in the initial sediment. This sediment may have been derived from the degradation of the associated komatiitic volcanics or may represent a contemporaneous reworked ultramafic tuff or ash flow.
Pelecocrinus sp. cf. P. banffensis Laudon, Parks, and Spreng, from the Banff Formation (Lower Mississippian), Kananaskis Valley, Alberta, Canada
Authors: McGugan Alan , Strimple Harrell L.
Published: April 2011

A new occurrence of Pelecocrinus cf. P. banffensis is described from the Banff Formation of Osage age, Kananaskis Valley, Alberta.
The 210Pb and 137Cs profiles in sediment cores from Lakes Matagami and Quevillon, northwest Quebec, Canada
Authors: Durham R. W. , Joshi S. R.
Published: April 2011

210Pb and 137Cs activities were determined in sediment cores from Lakes Matagami and Quevillon, northwest Quebec, Canada. Following correction for the compressive effect of sedimenting materials, present-day sedimentation rates have been calculated from the excess 210Pb profiles. The rates are found to be 0.81 mm∙year−1 (59 mg∙cm−2 ∙year−1) and 0.52 mm∙year−1 (35 mg∙cm−2∙year−1) in Lake Matagami and Lake Quevillon, respectively. 137Cs measurements are in accord with these values.
Carbonaceous megafossils from the Precambrian (1800 Ma) near Jixian, northern China
Authors: Hofmann H. J. , Jinbiao Chen
Published: April 2011

The upper part of the stratotype section of the Changcheng System in the Yanshan Range 100 km east of Beijing (Peking) has yielded small megascopic carbonaceous compressions assignable to Tyrasotaenia Gnilovskaya and Chuaria Walcott. These fossils are between 1700 and 1900 Ma old and may represent the oldest megascopic organisms now known.
A new specimen of Struthiomimus altus from Alberta, with comments on the classificatory characters of Upper Cretaceous ornithomimids
Authors: Nicholls Elizabeth L. , Russell Anthony P.
Published: April 2011

A new specimen of Struthiomimus altus is described from the Oldman Formation of Alberta. Ossified xiphisternal structures are present, which are similar to the posterolateral processes of the sternum of some birds. The gastralia are found to consist of two, rather than three, overlapping segments.Four genera of Upper Cretaceous ornithomimids are recognized: Struthiomimus, Ornithomimus, Dromiceiomimus, and Gallimimus. The structure of the manus is found to be the most reliable character suite distinguishing them. Dromiceiomimus, however, can still be distinguished only on the basis of limb proportions, and its recognition remains tentative until further material is forthcoming.
Paleomagnetism of the Great Slave Supergroup, Northwest Territories, Canada: multicomponent magnetization of the Kahochella Group
Authors: Reid A. B. , McMurry E. W. , Evans M. E.
Published: April 2011

Results are reported from 59 stratigraphic horizons spanning an aggregate of some 2000 m of sedimentary rocks of the Great Slave Supergroup, mostly located in the Kahochella Group. Partial demagnetization experiments and vector differences indicate that the magnetization involved is multicomponent, with a well-defined overprint masking an underlying magnetic component. The overprint has now been recognized in many formations of the Great Slave Supergroup and is interpreted as having been acquired in response to uplift and cooling following orogeny in the Coronation Geosyncline. It corresponds to a paleomagnetic pole at 91°W, 21°N (A95 = 5°). Removal of this overprint reveals the underlying, presumed primary, magnetization, which has a mean direction of D = 129°, I = +21° (N = 18 sites, k = 12, α95 = 10°) and a corresponding pole at 62°W, 7°S (K = 15, A95 = 9°). The ages of these poles cannot be fixed precisely, but the available data suggest that the "primary" remanence was acquired about −1.8 Ga, and the overprint about −1.7 Ga. The two poles thus help define the Precambrian polar wander curve for Laurentia. In particular they help define the so-called Coronation loop, which reflects the response of Laurentia to the major orogeny in the Coronation Geosyncline.
McNaughton Lake seismicity—more evidence for an Anahim hotspot?
Authors: Rogers Garry C.
Published: April 2011

The only notable concentration of earthquakes in the Canadian Cordillera away from the coastal zone occurs in the McNaughton Lake region of British Columbia, off the eastern end of the Anahim volcanic belt. The association of these two phenomena strengthens the hypothesis that the origin of the Anahim belt is due to North America overriding a mantle hotspot and provides a possible explanation for the concentration and character of the seismicity.
Rb/Sr geochronology in the Thompson belt, Manitoba: implications for Aphebian crustal development and metallogenesis
Authors: Brooks C. , Theyer P.
Published: April 2011

The supracrustal metasediments of the Thompson belt (Pipe and Thompson Groups) show pronounced differences in Rb/Sr age (1855–1685 and 1665–1575 Ma, respectively) and initial Sr ratio (0.7096–0.7166 and 0.7203–0.7233). However, they have similar Rb/Sr ratios (0.8–1.2), and the age and isotopic differences are attributed to differing degrees of postdepositional, metamorphic reworking. The Sr-growth trajectories of these metasediments define a broad band on the evolution diagram and indicate a probable (maximum?) age of deposition of ca. 2.0 ± 0.1 Ga. Furthermore, the role of Archean detritus in the depositional history of these sediments is quite limited, based on isotopic data for the basement gneisses and adjoining granulites of the Pikwitonei region.Comparison of these data with those for metagraywackes of the adjacent Kisseynew gneisses (average [Formula: see text]) indicates that there were fundamental differences between the marine environments within which the two Aphebian sedimentary sequences were deposited. The high Rb/Sr in the Thompson belt metasediments is interpreted to reflect a relatively "long" equilibration of authigenic clays with circulating seawater (open ocean?) whereas the lower Rb/Sr of the Kisseynew metasediments reflects rapid sedimentation in an eugeosynclinal environment dominated by juvenile Aphebian material.Combined K/Ar and Rb/Sr ages suggest that the metamorphic reworking of the Thompson belt metasediments had three phases, an early period of folding ([Formula: see text]), followed by cross-folding and amphibolite facies metamorphism corresponding to the main pulse of the Hudsonian Orogeny ([Formula: see text]), and finally, late-stage shearing, faulting, and retrograde metamorphism (1625–1550 Ma). Mafic to ultramafic magmatism and associated nickel mineralization are confined to the interval between the deposition of the Thompson belt supracrustals and the first phase of Hudsonian deformation (i.e., ca. 2.1–1.8 Ga).
Landslides at the south end of Kluane Lake, Yukon Territory
Authors: Clague John J.
Published: April 2011

Landslides are unusually varied and abundant in the Kluane Ranges near the south end of Kluane Lake, Yukon Territory. Selected landslides were investigated to determine the likelihood and probable character of future mass movements in this area, and to gain some understanding of similar but unstudied features elsewhere in the St. Elias Mountains.Landslides in the study area include slumps and related complex landslides, rockfalls, rockslides, rockfall avalanches, and debris flows. The youngest and most spectacular of the large catastrophic landslides is the Sheep Mountain rockfall avalanche (5–10 × 106 m3), which formed as a result of two separate failures between 500 and 1950 radiocarbon years ago. Much of the low mountain slope southwest of this landslide to near the mouth of Slims River is covered by thick blocky rubble deposited during one or more older catastrophic slope failures. Both the Sheep Mountain landslide and the set of older slope failures to the southwest apparently occurred when Kluane Lake was much smaller than it is today. As the level of the lake rose in response to aggradation accompanying the Neoglacial advance of Kaskawulsh Glacier, distal portions of these landslides were inundated.Debris flows and debris torrents occur sporadically on fans in the study area. These fans are composed of diamicton and gravel beds separated by loess layers and paleosols. Marker horizons, such as the Slims Soil (Hypsithermal) and White River tephra (ca. 1200 years BP), occur in these sediments and provide evidence that the fans have been active throughout the Holocene.Contributing factors to landslides in the eastern Kluane Ranges include high seismicity, the presence of steep slopes in pervasively fractured and faulted rocks, an abundance of talus and glacial sediments available for remobilization as debris flows and debris torrents, and the occurrence of intense rainstorms.Although landslides are ubiquitous in the south Kluane Lake area, most of the large deep-seated bedrock failures are relatively old. Thus the danger posed by future comparable landslides to life and property in the area could be considered to be low. Floods, debris flows, and debris torrents on active alluvial fans and aprons skirting the Kluane Ranges probably are greater potential hazards to economic development of this region.
Lower Cambrian cavity-dwelling endolithic (boring) sponges
Authors: Kobluk David R.
Published: April 2011

In the Lower Cambrian Forteau Formation (middle Bonnia–Olenellus zone) of southern Labrador, cavities in archaeocyath patch reefs contain preserved coelobiontic endolithic sponges. Scallops and carbonate chips produced by sponge boring, spicules, and preserved endolithic sponge body fossils all point to the presence of endolithic sponges in Lower Cambrian reef cavities.The oldest previously described endolithic sponges are Early Ordovician in age and the oldest previously known reef interior bioerosion is Middle Ordovician in age. The presence of endolithic sponges in reef cavities of the Forteau Formation therefore extends both the record of endolithic sponges and of reef interior bioerosion from the Ordovician to the upper Lower Cambrian.
The lead and strontium isotope geochemistry of metalliferous sediments associated with Upper Cretaceous ophiolitic rocks in Cyprus, Syria, and the Sultanate of Oman
Authors: Gale N. H. , Spooner E. T. C. , Potts P. J.
Published: April 2011

Metalliferous sediments consisting dominantly of fine-grained iron and manganese oxides and hydroxyoxides have been widely recorded from the crests of sea-floor spreading ridges and as a basal facies of the sediment accumulations of the oceanic crust. Similar sedimentary rocks that, in Cyprus, for example, contain 10–44 wt.% Fe and 2–16 wt.% Mn, occur in association with ophiolitic rocks. These chemical precipitates are thought to have formed by oxidation of hydrothermal fluid released in submarine hot-spring areas in the discharge zones of ocean-floor geothermal systems that contained convectively circulating sea water.Lead isotope ratios of 18 samples associated with Upper Cretaceous ophiolitic rocks of the Troodos massif, Cyprus (6 samples), the Baër-Bassit area, Syria (6), and the Semail nappe in the Sultanate of Oman (6), indicate that the metalliferous sediments contain lead leached from the underlying basaltic oceanic crust during hot water – rock interaction. The amount of basaltic lead varies from comparatively little, in some samples from Syria, to essentially 100% in many of the samples from Oman. Linear mixing relationships characterized by correlation coefficients of 0.97 and 0.86 are defined on 208Pb/204Pb–206Pb/204Pb and 207Pb/204Pb–206Pb/204Pb diagrams. The mixing lines connect the less radiogenic mid-ocean ridge basalt field with the more radiogenic sea-water lead field of manganese nodules, which is also the average isotopic composition of continental crustal material. Negative covariations with Th, a trace element index of the detrital sedimentary component, and Pb/Fe, a monitor of diagenetic addition of Pb from pore waters, suggest that the main cause of the lead isotopic variation was initial adsorption of a variable ratio of leached basaltic lead to dissolved sea-water lead.The mean of 13 initial 87Sr/86Sr ratios (0.7079 ± 0.0013; 2 SD) is statistically indistinguishable from the estimated 87Sr/86Sr ratio for Late Cretaceous sea water at 0.7076 ± 0.0006 (25 values; Peterman et al.). Hence, strontium was largely derived by adsorption from sea water. However, three determinations are significantly more radiogenic than Late Cretaceous sea water. A statistically significant covariation with Rb (r = 0.78), one of the trace elements contained in the detrital, sedimentary component, suggests that the increase was caused by a variable admixture of terrigenous material.Neither lead nor strontium isotope ratios nor trace element concentrations suggest significant diagenetic modification of the isotopic compositions of the metalliferous sediments.
Regional stratigraphy and structural setting of the Kamloops Group, south-central British Columbia
Authors: Ewing Thomas E.
Published: April 2011

The Kamloops Group is redefined as an assemblage of Lower to Middle Eocene volcanic and sedimentary rocks widespread in south-central British Columbia. In the type area west of Kamloops, the basal Tranquille Formation consists of 500 m of lacustrine and deltaic sediments, pillowed flows, and hyaloclastites. Elsewhere, basal coal-bearing nonvolcanic fluvial and lacustrine units occur, such as the Coldwater Formation at Merritt, the Chu Chua Formation at Barriere, and the Shorts Creek Formation west of Vernon. Overlying these formations are dominantly volcanic units. At the type area, the Dewdrop Flats Formation includes over 1000 m of interstratified basaltic andesite flows, andesitic flow-breccia sheets and cones, basaltic tuff rings, and an andesitic composite cone. Elsewhere, flat-lying basaltic andesite flows about 600 m thick with local flow breccias are common.The basal sediments accumulated in separate fault-bounded basins initiated immediately before the onset of volcanism. These volcanic rocks filled the basin and formed a widespread volcanic blanket, which was disrupted by continued fault movement. The numerous basins are linked by a throughgoing fault network with up to 12 km of net right-lateral strike-slip displacement.
Paleomagnetism of the Late Proterozoic sills in the Tsezotene Formation, Mackenzie Mountains, Northwest Territories, Canada
Authors: Park J. K.
Published: April 2011

A paleomagnetic study was conducted on a regionally extensive diabase sill intruding the upper part of the Helikian (?) Tsezotene Formation located in the Mackenzie Mountains Supergroup of northwestern Canada. Twelve sites, one from a lower sill at one locality, were sampled over a distance of about 200 km. Two general magnetizations presumably carried by maghemite (AR: 38 specimens; 272°, 00°; pole 139°E, 01°N; K = 34, A95 = 4°) and hematite (B: 18 specimens; 269°, −01°; pole 141°E, 01°S; K = 21, A95 = 7°) were resolved by using a two-stage treatment method (alternating field treatment of 20–45 mT followed by thermal demagnetization to about 650 °C) in combination with vector subtraction and vector diagrams. B has normal (BN: 6 specimens) and reverse (BR: 17 specimens) components. Another magnetization (RM: 30 specimens; 086°, + 55°; k = 3) carried by magnetite appears to be a resultant of normal and reverse components, though it may include a secondary Cretaceous component. It is likely that the maghemite and hematite are deuteric alteration products of the magnetite and that they retain the primary direction probably residing in the unresolved magnetite components of RM.
Ice action on lakeshores near Schefferville, central Quebec – Labrador, Canada
Authors: Pyökäri Mauri
Published: April 2011

Ice-push action causes considerable shore and vegetation damage on lakes located 10–40 km southeast of Schefferville in central Quebec – Labrador. The damage occurs mainly on shores of large lakes; on small ones the damage is slight. In the spring the wind-driven ice thrusting up on the shores moves shore material, even quite large stones, and forms fine ice-push ridges. It also uproots trees and shifts them far landward. The ice-made features on shores of large lakes are common: they occur on 46% of the shores. In addition, there is slight vegetation damage on 32% of the shores; only 22% of the shores lack signs of ice push. Ice push is a major process moulding the shorelines of these lakes.
Minimum age of deglaciation of upper Elk Valley, British Columbia
Authors: Ferguson Angus , Osborn Gerald
Published: April 2011

Bog sediments at an elevation of 1582 m in the upper Elk Valley of British Columbia were dated at three horizons. The lowermost of these, radiocarbon dated at 13 430 ± 450 years BP, provides a minimum age for deglaciation of Elk Valley. This date is probably also a minimum for the Canmore advance in the Bow Valley, Alberta, and suggests that the Canmore was not related to deposition of the Bighill Creek Formation at Cochrane. Pollen samples from the bog indicate a shrub–herb pioneer assemblage following deglaciation of that portion of the valley.
Paleocene orthopteroids from south-central Alberta, Canada
Authors: Kevan D. Keith McE. , Wighton Dennis C.
Published: April 2011

New Paleocene orthopteroid taxa from the Paskapoo Formation are described. All are represented by adult wings. Albertoilus cervirufi n.gen., n.sp. (superfamily Hagloidea, family Prophalangopsidae, subfamily Prophalangopsinae) is a descendant from the same stock as the Jurassic Aboilus. Phasmomimella paskapoensis n.gen., n.sp. and Phasmomimula enigma n.gen., n.sp. (superfamily Phasmomimoidea, family Phasmomimidae) extend the known existence of the family from the Early Cretaceous to the Paleocene; they are the most advanced and first recorded American phasmomimids. Pseudotettigoniinae n.subfam. (superfamily Tettigonioidea, family Tettigoniidae) is proposed to include the primitive genera Pseudotettigonia Zeuner (type genus), Arctolocusta Zeuner, and Nymphomorpha Henriksen. Genus and species incertae sedis, the oldest recorded tettigonioid, with primitive venation, is assigned to the new subfamily. Promastacidae n.fam. (superfamily Eumastacoidea) is erected to include the early Tertiary type genus Promastax Handlirsch and the oldest and most primitive eumastacoid, Promastacoides albertae n.gen., n.sp. The closest relatives of the new family are the Tertiary and Recent Eruciidae.
Palynological evidence for recycling of Upper Devonian into Lower Cretaceous of the Moose River Basin, James Bay Lowland, Ontario
Authors: Legault Jocelyne A. , Norris Geoffrey
Published: April 2011

Cored drill hole on a high electromagnetic conductivity anomaly near the Onakawana lignite field penetrated 50.3 m of Pleistocene, Cretaceous, and Devonian strata. Spore–pollen floras from the Cretaceous interval indicate an early middle Albian age and a correlation with the lower part of the Mattagami Formation. Spores, acritarchs, and tasmanitids from the Devonian interval indicate that the upper part of the Long Rapids Formation is marine and is Frasnian–Famennian in age. Multiple recycling events are documented between the Devonian and Cretaceous and between the Cretaceous and Pleistocene, provenances being local near the margins of the basin.
Quartz deformation and the recognition of recrystallization regimes in the Flinton Group conglomerates, Ontario
Authors: White Joseph C.
Published: April 2011

The clastic metasedimentary rocks that form the Flinton Group occur as arcuate belts within the Grenville Structural Province, southeastern Ontario. Metamorphic isotherms transect these rocks and allow comparison of deformation over an approximate temperature range of 550–650 °C. Two geometrically discrete but temporally continuous deformation phases contribute significantly to pebble deformation within the conglomeratic units. There is a general increase in both finite strain, over which there is a strong compositional control, and the frequency of D2 minor structures with increasing metamorphic temperature. D1 is characterized by the creation of a subgrain structure and progressive misorientation of the subgrains as strain accumulates. Ultimately this leads to formation of high-angle boundaries defining recrystallized grains of a size similar to that of the precursor subgrains. D2 produces a new, finer subgrain structure, elongated grains, grain boundary migration (bulging), and small recrystallized grains. Empirical relationships between stress and subgrain diameter suggest that D1 is a low stress (5–6 MPa) deformation and D2 is a higher stress (12–80 MPa) deformation. This emphasizes that rotation recrystallization defines a low-temperature, low-stress regime, whereas migration recrystallization is typical of higher temperatures and stresses. Although dislocation creep predominates in most pebble types, evaluation of the deformation in terms of non-uniform flow laws can explain the compositional control of strain in the quartzite pebbles and suggests that significant grain boundary sliding occurred.
Redefinition of the Quetico Fault near Atikokan, Ontario
Authors: Fumerton S. L.
Published: April 2011

Recent mapping has shown that west of Atikokan the Quetico Fault, which is generally considered to represent part of the boundary between the northern Wabigoon and the southern Quetico Subprovinces in this region, is composed of two separate fault systems and should not have one name. The single fault system that defines the boundary between the Quetico and Wabigoon Subprovinces in this area, and includes the Seine River Fault, should all be termed the Quetico Fault as this name has precedence. To avoid confusion, the other fault system that is entirely in the Wabigoon Subprovince should have a new name, and the term Little Turtle Fault is suggested.
The geological significance of endolithic algae in glass
Authors: Jones Brian , Goodbody Q. H.
Published: April 2011

Calcified filaments of Ostreobium are common in beachrock on Grand Cayman Island. The alga exhibits an epilithic, chasmolithic, and endolithic mode of life. In its endolithic mode it bores into carbonate allochems and apparently uses the Mg and Ca so derived in calcifying the filament in its epilithic or chasmolithic mode. Glass fragments, cemented in the beachrock, are also bored by algae in a manner similar to the carbonate allochems. The Si dissolved by the alga in its boring phase is incorporated, along with Ca and Cl, in the algal sheath.The fact that algae can bore into glass suggests that they do not assume an endolithic life mode in order to obtain organic nutrients or moisture. The algae assume this life habit because of external pressures such as wave energy or simply because the algae bore into any available substrate. This example also demonstrates that algae are capable of secreting substances that can dissolve silica.
Extent of Grenvillian remanence components in rocks of the Southern Province
Authors: Stupavsky M. , Symons D. T. A.
Published: April 2011

Early Aphebian Gowganda sedimentary rocks and intruding Nipissing diabase sills were sampled for paleomagnetic study at 88 sites (~500 cores, ~1000 specimens) along two ~42 km long profiles extending north from the Grenville Front into the Cobalt Plate of the Southern Structural Province in the River Valley – Lake Temagami area of Ontario. After AF demagnetization a postfolding pre-Nipissing ~2200 Ma remanence was found in eight of the 37 Gowganda sediment sites that were > 2 km north of the front, giving a pole at 109°W, 63°N (dp = 10°, dm = 19°). The Nippissing diabase from > 2 km north of the front retains a stable antiparallel prefolding N1 remanence direction in 22 of 40 sites, giving a pole position of 85°W, 17°S (dp = 6°, dm = 10°). These "south and down" remanence directions found in the southern portion of the plate contrast with the antiparallel "north and up" directions found in the northern portion, thereby indicating the occurrence of either two nearly cogenetic Nipissing intrusive events or the sequential emplacement of the Nipissing during an Earth's magnetic field reversal across the plate. At two sites a Nipissing remagnetized remanence was found in Gowganda sediments with a pole of 115°W, 18°S. Also three "Nipissing" sites give a pole at 164°W, 3°N, which is close to the known pole for the later ~1.25 Ga Sudbury olivine diabase dikes. One site is adjacent to a large dike and two were found on thin-section examination to be olivine diabase. The eight sites in Gowganda sediment matrix and conglomerate clasts and in Nipissing diabase from within < 2 km from the front were found to have a postfolding metamorphic remanence with a Grenville orogenic pole at 45°W, 51°N (dp = 19°, dm = 21°). Finally, the results lead to a suggested revision in the APW path for the ~2300–~1650 Ma interval for North America.
U–Pb zircon ages from the eastern Savant Lake – Crow Lake metavolcanic–metasedimentary belt, northwest Ontario
Authors: Davis D. W. , Trowell N. F.
Published: April 2011

Five rocks from three areas in the eastern part of the Savant Lake – Crow Lake metavolcanic–metasedimentary belt have been dated by U–Pb analysis of zircons.The Sioux Lookout area is composed of a sequence of generally fault-bounded metavolcanic and metasedimentary belts. The age of a felsic tuff in the Central volcanic belt is [Formula: see text]. This is possibly the youngest sequence in the area.The Savant Lake volcanic belt comprises the Jutten volcanic unit at its base separated by an angular unconformity from the Handy Lake volcanic sequence. The age of a dacitic tuff near the base of the Handy Lake volcanic sequence is [Formula: see text].The South Sturgeon Lake volcanic belt is composed of four volcanic cycles. The age of a felsic tuff from the top of the uppermost cycle is [Formula: see text]. The felsic Beidelman Bay pluton and the mafic Pike Lake pluton, which both intruded the lower part of the sequence, give ages of [Formula: see text] and [Formula: see text], respectively. This establishes a minimum time span of [Formula: see text] for deposition of the sequence. This interval, along with the 27 Ma span between the ages of the Handy Lake sample and the volcanic sample from the South Sturgeon Lake area, suggests that the sequences were laid down by a series of discrete volcanic episodes.For samples subjected to multistage lead loss, the reliability of ages has been greatly enhanced by air abrasion of zircons. Several cases of suspected biasing of analyses by the air abrasion process have been encountered. It appears that this biasing problem can be overcome by selection and abrasion of low uranium grains that are free of imperfections.
Alpine ultramafic rocks of southwestern British Columbia
Authors: Wright R. L. , Nagel Joe , McTaggart K. C.
Published: April 2011

Ultramafic rocks of the Hozameen, Bridge River, and Cache Creek ophiolite assemblages show much variety. The Coquihalla belt of the Hozameen ophiolite assemblage, almost completely serpentinized, is elongate, narrow, and lies along a major fault. Three ultramafic bodies from the Bridge River ophiolite differ markedly from each other. (1) The Pioneer peridotite is a relatively small lens (4 km by 2 km), unaltered, well layered, and fault bounded. (2) The Shulaps body, one of the largest in British Columbia, is bounded on the northeast by a major fault and shows a wide mélange zone on the southwest. (3) A serpentinite body at Lillooet appears to be a steeply dipping slab in the Fraser River fault zone. At Cache Creek, serpentinite bodies are small and appear to be fragments in a mélange. Layers, transgressive sheets, and pods in the Pioneer and Shulaps bodies originated in the mantle, probably by one or several processes: metamorphic differentiation, metasomatism, and mechanical injection. Some ultramafic bodies were emplaced onto the crust by obduction but others, strongly serpentinized, that lie in fault zones may have been squeezed into their present positions.
Stratigraphic relationships and paleoecology of a late-glacial peat bed from the Queen Charlotte Islands, British Columbia
Authors: Mathewes Rolf W. , Clague John J.
Published: April 2011

The stratigraphic relationships of late-glacial and Holocene sediments exposed in sea cliffs at Cape Ball on the Queen Charlotte Islands are summarized, based on section descriptions and 13 radiocarbon dates on wood, peat, and marine pelecypod shells. One peat bed dated at 12 400 ± 100 years BP (GSC-3112) to 10 200 ± 90 BP (GSC-3159) was investigated for pollen and plant macrofossils. This study extends the late Pleistocene vegetation history of the Queen Charlotte Islands by about 1550 years, and suggests that the record will date back to before 13 700 ± 100 BP (GSC-3222).Four local pollen zones are described from the 70 cm thick peat, beginning with a 7 cm thick herb-dominated zone (CB-1), characterized by up to 60% grass pollen, and including a unique assemblage with abundant Apiaceae, Cyperaceae, Empetrum/Ericaceae, Polemonium, Plantago macrocarpa, Fritillaria, and Ranunculus. A high diversity of other herbs, including subalpine/alpine species and two taxa presently absent from the Charlottes (Armeria maritima and Polemonium caeruleum type), suggests that this zone represents an open floodplain vegetation with no modern analogue. Zone CB-2 (63–45 cm) is dominated by Pinus conforta type pollen (65–70%) and moderate values for fern spores. Zone CB-3 (45–30 cm) shows a rapid rise of Picea pollen from 3 to 39%, followed by a drop to about 12%. Fern spores (20–50%) and Alnus (6%) also reach maximum levels in this zone. Abundant wood fragments and sand inclusions are compatible with an interpretation of a swampy floodplain forest during this interval. The uppermost zone (30–0 cm) exhibits high Pinus contorta (40–60%) and Cyperaceae (12–38%) values, along with a moderate abundance of grasses, ferns, and Apiaceae. Estuarine and marine sediments with pelecypod shells, deposited during a marine transgression, overlie the peat bed.Implications for the controversy over the existence of late Pleistocene refugia in the Charlottes are briefly discussed.
34S and 18O abundances differentiate Upper Cambrian and Lower Devonian gypsum-bearing units, District of Mackenzie, N.W.T.—an update
Authors: Everdingen Robert O. van , Shakur M. Asif , Krouse H. Roy
Published: April 2011

Previous sulfur isotope data for the Lower Devonian Bear Rock Formation and the Upper Cambrian Saline River Formation in the District of Mackenzie, N.W.T. have been supplemented by additional sulfur isotope analyses as well as δ18O determinations on sulfates from outcrops, drill cuttings, and cores. Whereas the mean δ34S value for the Bear Rock Formation is lower than that of the Saline River Formation (+17.8 ± 1.8‰ versus +29.7 ± 2.2‰), the opposite trend was found for the mean δ18O values (+15.6 ± 1.0‰ versus +13.0 ± 1.5‰). The new data confirm that, for all samples analysed, there is no overlap between δ34S values for the two formations, while the δ18O data display some overlap. The earlier δ34S data for samples from an evaporitic section on the northeast side of the Norman Range (originally mapped as consisting entirely of Saline River Formation) indicated the presence of a thrust fault in the section, with Saline River strata overlying Bear Rock strata. The δ18O data for those samples, which fortuitously fall into two non-overlapping groups, confirm the earlier conclusions based on the δ34S data and allow us to define the position of the thrust-fault contact somewhat more closely.
Paleomagnetism of the Sutton Lake Proterozoic inlier, Ontario, Canada
Authors: Schwarz E. J. , Clark K. R. , Fujiwara Y.
Published: April 2011

Thirty-eight cores were collected from eight sites in the Sutton Lake Proterozoic inlier, which is thought to be an extension of the Circum-Ungava Belt. Six sites from a 100 m thick diabase sill yielded essentially single-component magnetization averaging D = 35°, I = −54°, k = 39,α95 = 11°. The diabase dips north at 4° and shows only minor alteration (epidote and chlorite). The other two sites were in a fine-grained dark layer within the sill and in a dike. No end points were observed for these sites upon alternating field and thermal demagnetization. The six diabase sites yielded a north pole at 67°E, 3°S, dm = 15, dp = 11. This pole position is similar to that obtained for the youngest volcanic suite (Flaherty Formation) of the Belcher Islands and to that obtained for red beds of the La Grande 4 outlier, suggesting a time-stratigraphic correlation between these units.
Conodonts and the position of the Ordovician–Silurian boundary at the eastern end of Anticosti Island, Québec, Canada
Authors: Nowlan Godfrey S.
Published: April 2011

Conodonts have been recovered from a section spanning the Ordovician–Silurian boundary at the eastern end of Anticosti Island. They indicate that the systemic boundary lies slightly above or at the top of a pisolitic limestone bed. This placement of the boundary compares closely with that based on a previous interpretation of brachiopod faunas from the same section, and also with the position of the systemic boundary based on conodonts elsewhere on Anticosti Island. The conodonts are the first to be reported from the eastern end of Anticosti Island.
Geochemical denudation rates and solute transport mechanisms in a maritime temperate glacier basin
Authors: Eyles N. , Sasseville D. R. , Slatt R. M. , Rogerson R. J.
Published: April 2011

Dissolved cation loss from the basin of Berendon Glacier, northwestern British Columbia is calculated at 947 mequiv m−2 year−1 with calcium accounting for nearly all of this loss. This geochemical denudation rate is substantially greater than the world average of 390 mE m−2 year−1 but agrees well with similar studies from the Cascade Range in the northwestern United States. Abundant precipitation is likely responsible for the significant geochemical denudation despite reduced chemical activity at low annual temperatures. When absorption is considered in the removal process, the major cation denudation rate increases by about 10% and doubles the loss of certain cations such as sodium. This finding complements previously published sedimentological evidence (SEM of quartz grains) of high rates of chemical activity in the basin.Debris–water contact time appears to exert a significant control on the cation and silica concentrations exhibited by the various water types moving through the basin. Firn, glacier ice, and supraglacial streams generally possess the lowest ionic concentrations, and subglacial streams, valleyside streams, and ponds generally contain the highest. The geochemical signature of meltwaters is established rapidly and field-filtering of water samples is critical to the prevention of desorption and mineral dissolution.Anthropogenic chemical input to the Berendon basin is measurable and consists of trace metal rich dust originating at a mining and milling operation close to the glacier terminus. Aeolian transport is responsible for distributing Cu, Cr, Ni, and Pb throughout the watershed; trace metal rich dust could be utilized as a stratigraphic marker for future studies of snow accumulation above the firn line.
Rb–Sr and U–Pb ages of volcanism and granite emplacement in the Michipicoten belt—Wawa, Ontario
Authors: Turek A. , Smith Patrick E. , Schmus W. R. Van
Published: April 2011

The Michipicoten greenstone belt at Wawa, Ontario is typical of Archean volcanic belts in the Superior Province. The supracrustal rocks are divisible into lower, middle, and upper metavolcanic sequences, which are separated by iron formation and clastic metasedimentary rocks. These are intruded by granitic stocks and embayed by granitic batholiths.This study reports whole rock Rb–Sr and zircon U–Pb ages for the lower and upper metavolcanics, for the granitic rocks that are physically within the greenstone belt (internal granites), and for the granitic rocks that embay the greenstone belt (external granites). The apparent Rb–Sr ages for the lower metavolcanics are 2530 ± 90, 2285 ± 70, and 2680 ± 490 Ma. The U–Pb ages are 2749 ± 2 and 2744 ± 10 Ma. The internal granites give an Rb–Sr age of 2560 ± 270 Ma and a U–Pb age of 2737 ± 6 Ma. The external granite at Hawk Lake indicates an Rb–Sr age of 2550 ± 175 Ma and a U–Pb age of 2747 ± 7 Ma. It is possible that this unit contains elements older than 2812 Ma as it contains xenocrystic zircons. The upper volcanics give a U–Pb age of 2696 ± 2 Ma, which indicates that the belt evolved over a time period in excess of 53 Ma. The Rb–Sr ages are significantly younger than the U–Pb zircon ages and have very large uncertainties in age; hence it is unlikely that they have any stratigraphic significance. They probably reflect the Kenoran orogeny at about 2560 Ma. The 2285 ± 70 Ma Rb–Sr isochron age has an initial ratio of 0.7275 ± 0.0052, which is interpreted as a rotational isochron defining a younger post-Kenoran event in the area. The zircon ages appear to be correct chronostratigraphically. Furthermore, it appears that the granitic rocks are coeval and may also be cogenetic with the lower acid metavolcanic rocks.