bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Factor and Regression Analysis in the Interpretation of Geochemical Reconnaissance Data
Authors: Closs L. G. , Nichol Ian
Published: April 2011

The interpretation of exploration oriented geochemical data frequently requires the recognition of subtle features related to mineralization, from the more obvious geochemical expressions of bedrock and surface environments. A number of previous investigations have indicated the potential of various computerized interpretational procedures as aids in identifying these features in geochemical data. The present investigation was concerned with the interpretation of multi-element data from a 750 mile2 {1942.5 km2) area of the Notre Dame Bay district of Newfoundland. The area is underlain by a series of Ordovician and Silurian sediments and volcanics and intrusives overlain by glacial deposits mostly composed of glacial till. Massive sulfide mineralization including the Whalesback and Gullbridge deposits occur within the Ordovician volcanics. R mode factor analysis was employed to establish the character and distribution of the principle metal associations related to bedrock and surface environment contributing to the overall data distribution. The factor scores were regressed against the individual metal concentrations of the elements composing the respective factors, the resulting residuals of the metals reflecting the component of metal related to some sources other than those reflected by the metal associations established by factor analysis. Anomalous areas of residual copper and zinc distributions indicate the areas of known sulfide mineralization more closely than the untreated metal distributions. On this basis, anomalous areas of residual copper and zinc, unrelated to known sulfide mineralization warrant further exploration investigation. It is therefore concluded that a combination of factor and regression analysis on multi-element data from the Notre Dame Bay district of Newfoundland serves to highlight subtle though significant features in multi-element data possibly related to mineralization that were not apparent from a consideration of the untreated data.
Evidence for the Emergence of the Hercynian Front on the North American Continent
Authors: Cherkis Norman Z. , Fleming Henry S. , Massingill James V. , Feden Robert H.
Published: April 2011

Recent marine seismic reflection, bathymetric and magnetic measurements made across the Charlie Gibbs Fracture Zone have clearly shown that the fracture zone extends to the east of 17 °west longitude. Projections to the west of the Mid-Atlantic Ridge extend the fracture zone to the North American Continental margin northeast of Newfoundland. Projection of the structural trends of the Hercynian Front from the European continental margin offer a remarkable linearity with the Charlie Gibbs Fracture Zone on the west. Remnants of the Hercynian Front have been identified in New Brunswick. Flemish Cap, which foundered during the initial phase of the latest opening of the Atlantic is believed to have been located on the fracture zone's southern edge, before drifting southeasterly to its present position. The alignment of the Hercynian Front with the Charlie Gibbs Fracture Zone is linked up on the North American continent and is offered as a possible clue to the pre-drift configuration of the Laurasian continent.
Sedimentation in Lillooet Lake, British Columbia
Authors: Gilbert R.
Published: April 2011

Sediment from Lillooet River Basin, 3580 sq km of alpine and subalpine landscape, 7% of which is glacier-covered, is deposited in Lillooet Lake. During the summer when the lake is stratified by temperature and suspended sediment content, processes of interflow and underflow distribute sediment throughout the lake and give rise to a distinctive sedimentary sequence of varved silts and clays interspaced irregularly with massive beds of coarser grained sediments up to 120 mm thick. Coarse sediment deposited on the proximal delta slope is redistributed by infrequent slumps; mounds of slumped material cover the foreset slopes to their base at 120 m depth. Thickness of varves is related to the annual inflow to the lake, and continuous records of water temperature near the lake bottom indicate that the numerous laminae within varves are due to intermittent underflow events.
The Middle–Upper Cambrian Transition in Southeastern Newfoundland, Canada
Authors: Poulsen Valdemar , Anderson Michael M.
Published: April 2011

The Middle-Upper Cambrian transition in southeastern Newfoundland is shown to be very similar to the transition in Scandinavia and in the English Midlands. The late Middle Cambrian Lejopyge laevigata Zone, which is recorded for the first time from eastern Canada, is contained in the basal part of the Elliott Cove Formation and is conformably overlain by the Upper Cambrian Agnostus pisiformis Zone. The following trilobite species from the Lejopyge laevigata Zone at Manuels River and on Random Island are described: Andrarina costata (Angelin), Paradoxides sp., Lejopyge laevigata (Dalman), and Peronopsis insignis (Wallerius).
Revision of the Oxford Formation (Arenig) of southeastern Ontario and northern New York State
Authors: Bond Ivor J. , Greggs Robert G.
Published: April 2011

The Oxford Dolomite of southeastern Ontario is considered to be equivalent to the Ogdensburg Dolomite of northern New York State. The Oxford Formation is redefined in terms of its lithology, distribution, thickness, sedimentary environment, and age.A series of representative sections can be correlated with wells drilled in southeastern Ontario. The formation rests disconformably upon the March Formation (Tremadocian) and is overlain disconformably by Middle Ordovician (Chazyan) sediments. The lower contact of the formation is widely exposed, but the upper contact is known only from boreholes.Lithologies are not distinctive; a lower division in which quartz sand is abundant and an upper division in which it is rare or absent can be recognized. The total thickness of the formation is not known; however, a minimum thickness of 605 ft (184.5 m) is present in a well near Williamsburg, Ontario. Conodont faunas indicate that the age of the Oxford is Lower Arenig and the disconformity at the base of the formation marks the base of the Arenig series in the Ottawa – St. Lawrence Lowlands.
Determining axes, axial planes, and sections of macroscopic folds using computer-based methods
Authors: Charlesworth H. A. K. , Langenberg C. W. , Ramsden J.
Published: April 2011

The fold-axis is the eigenvector associated with the smallest eigenvalue of a symmetrical 3 × 3 matrix of direction cosines of poles to the folded surface, only if the fold is cylindrical. Cylindricity can be tested using either a χ2 or an F test. Sections showing the traces of macroscopic surfaces and of the axial plane may be constructed with the aid of computer plots that show the projection of each outcrop as well as the trace of the folded surface. The orientation of the axial plane can be calculated from the orientations of the fold-axis and the trace of the axial plane on a section normal to the fold-axis. These numerical procedures are illustrated by an analysis of four folds from the Rocky Mountains.
The oldest known North American occurrence of the Plesiosauria (Reptilia: Sauropterygia) from the Liassic (Lower Jurassic) Fernie Group, Alberta, Canada
Authors: Nicholls Elizabeth L.
Published: April 2011

A partial skeleton of a plesiosaur, referable to the Plesiosauridae, from the lower Fernie Group (Sinemurian, Lower Jurassic) of Alberta is the oldest known occurrence of the Plesiosauria in North America.
A case study of the time and nature of paleomagnetic resetting in a mafic complex in New England
Authors: Schutts L. D. , Brecher A. , Hurley P. M. , Montgomery C. W. , Krueger H. W.
Published: April 2011

It appears that a hydrothermal alteration and development of magnetite is largely responsible for a paleomagnetic resetting in a belt of mafic–intermediate rocks in eastern Massachusetts. The age of this thermal and metasomatic event is found to be about 370 m.y. by both geochronological and paleomagnetic evidence. This age does not coincide with the emplacement of plutons within the region (600 and 450 m.y.), nor with the 340 m.y. uplift and cooling shown by K–Ar ages on biotites.The age and tentative pole position obtained favour the hypothesis that an eastern region in New England and Maritime Canada comprised a single block in the Devonian that was separate from North America at that time, and fits the polar wanderpath of North Africa.
The distribution and partition of zinc, copper, and lead in the sediments of the Saguenay fjord
Authors: Loring D. H.
Published: April 2011

Zinc (Zn) concentrations vary between 43 and 145 ppm, copper (Cu) concentrations between 6 and 33 ppm, and lead (Pb) concentrations between 14 and 66 ppm in relation to sediment texture and location in the Saguenay fjord. The concentrations of the elements increase with decreasing grain size; the highest concentrations occur in the fine grained sediments (muds) in the upper part of the fjord and they decrease downstream. On the average, the fjord muds are enriched in Zn and Pb when compared to sediments from the St. Lawrence estuary and the open Gulf of St. Lawrence.Acetic acid extractions of the sediments indicate that 14 to 29% of the total Zn, 14 to 21% of the total Cu, and 12 to 25% of the total Pb is contributed by the non-detrital (acid soluble) fraction, and the remainder (70–88%) is contributed by the detrital (acid insoluble) fraction. Most of the Zn, Cu, and Pb in the detrital fraction is held in discrete sulphide minerals. These minerals accumulate at the same rate as other detrital sedimentary material in response to the present depositional conditions. Non-detrital Zn, Cu, and Pb contributions represent the portion of the total element content adsorbed by fine grained inorganic and organic material during transport and deposition. The distributions of non-detrital Pb and to a lesser extent of Zn and Cu in the fjord are apparently controlled by the downstream dispersal from local industrial sources of mercury (Hg)-rich terrestrial organic matter.
Granitic magmas: possible and impossible sources, water contents, and crystallization sequences
Authors: Wyllie Peter J. , Huang Wuu-Liang , Stern Charles R. , Maaløe Sven
Published: April 2011

The calc-alkalic rocks of batholiths or their precursors may be generated in deep continental crust, in subducted oceanic crust, in the mantle wedge above, or in processes involving material from all three sources. For the series gabbro–tonalite–granite, we have phase relationships with excess H2O to 35 kbar (3500 MPa), and the H2O-undersaturated liquidus surfaces mapped with contours for H2O contents and with fields for near-liquidus minerals. Isobaric diagrams with low H2O contents provide grids potentially useful in defining limits for the H2O content of magmas, based on the sequence of crystallization. Conclusions from the experimental framework include: (1) The H2O content of large granitic bodies is less than 1.5%. (2) Primary granite magmas can not be derived from the mantle or subducted ocean crust. (3) Primary granite magmas with low H2O content are generated in the crust, and erupted as rhyolites. (4) Primary tonalite and andesite are not generated from mantle peridotite; the H2O contents required are unrealistically high. (5) Primary tonalite and andesite are not generated in the crust unless temperatures are significantly higher than those of regional metamorphism. (6) Subducted ocean crust yields magmas with intermediate SiO2 content, but not primary tonalite and andesite. (7) Batholiths are produced from crustal rocks as a normal consequence of regional metamorphism, with the formation of H2O-undersaturated granite liquid and mobilized migmatites. Some batholiths receive in addition contributions of material and heat from mantle and subducted ocean crust.
The Gander–Avalon Zone boundary in southeastern Newfoundland
Authors: Blackwood R. F. , O'Driscoll C. F.
Published: April 2011

The Dover Fault, characterized by a 300–500 m wide mylonite zone, separates the Gander and Avalon Zones in northeastern Newfoundland and formed in association with the Precambrian regional deformation that overprints these zones. In southern Newfoundland, foliated granitic rocks of the Gander Zone are separated from non-foliated granites and clastic sedimentary and volcanic rocks (Connaigre Bay Group) of the Avalon Zone by a 50–100 m wide breccia zone called the Hermitage Bay Fault. Relationships along the Hermitage Bay Fault suggest that it is an Acadian structure that modifies the original Precambrian mylonite zone.
Archean rocks from the eastern Lac Seul region of the English River Gneiss Belt, northwestern Ontario, part 2. Geochronology
Authors: Krogh T. E. , Harris N. B. W. , Davis G. L.
Published: April 2011

The region is divided into two domains, which are defined by their contrasting petrology, structure, and aeromagnetic anomaly pattern. The northern domain is underlain by east-trending, steeply south-dipping, migmatized garnet–biotite paragneiss. The southern domain is underlain by gneissic tonalite and trondhjemite, intruded by granite plutons, and with abundant amphibolite inclusions.Twelve U–Pb isotopic age determinations of zircons from two gneisses and four granite bodies from the eastern Lac Seul region of the English River Gneiss Belt indicate the following sequence of events. The tonalite gneiss of the southern domain was emplaced definitely more than 3008 m.y. ago and probably more than 3040 ± 40 m.y. ago. Local anatexis or injection associated with regional metamorphism produced a local pegmatite leucosome in the paragneiss 2681 ± 20 m.y. ago. Late- or post-orogenic granites, which invade both the paragneiss and the tonalite, were emplaced 2660 ± 20 m.y. ago, after the major metamorphism in the region. The youngest rock in the area, a cross-cutting pegmatitic granite, was emplaced 2560 ± 40 m.y. ago.
Oceanic fracture zones do not provide deep sections in the crust
Authors: Francheteau J. , Choukroune P. , Hekinian R. , Pichon X. Le , Needham H. D.
Published: April 2011

Data from rock-dredging have often been used to infer that oceanic fracture zones provide a 'window' into layers of the oceanic crust lying at a depth below the surface that is approximately equivalent to the vertical offset of the fracture zone, and thus permit the reconstruction of a crustal stratigraphy for the whole of acoustic layer 2 (commonly considered to have an average thickness of ~2 km) and, in some interpretations, for the upper part of layer 3. Alternatively, it has been suggested that fracture zones are preferential sites of serpentinite mega-dykes differing in composition from layer 3 but containing inclusions of the third layer. The published data indicate that basalts and basaltic rubble are abundant in fracture zones and, on analysis, do not justify the assumptions that have been made. The structure of fracture zones limits the possible extent of crustal sections exposed on their walls. Moreover, it is suggested that rocks of different layers of the lithosphere can be emplaced in the transform domain due to the dynamic of the transform fault system, itself.
Geology and geochemistry of the St. Lawrence peralkaline granite and associated fluorite deposits, southeast Newfoundland
Authors: Teng H. C. , Strong D. F.
Published: April 2011

The southern part of the Burin Peninsula of southeast Newfoundland is marked by extensive Carboniferous granite magmatism, intruding Late Precambrian to Middle Cambrian volcanic and sedimentary rocks. The St. Lawrence pluton, representative of this Carboniferous magmatism, ranges from equigranular to porphyritic in texture, displays much evidence of gas brecciation, and contains no pegmatites or schlieren, all features of high-level intrusion. The bulk chemistry corresponds to cotectic compositions in the synthetic Q–Ab–Or–H2O system for 500 bar [Formula: see text], likewise suggesting shallow levels of intrusion and crystallization. The granite is alkaline to peralkaline and of commenditic affinity, with agpaitic indices around 1 and modal aegirine and riebeckite. Its chemical affinity with less silicic alkaline granites of the same age in southeast Newfoundland suggests an origin by differentiation of such granites. A high initial Sr87/Sr86 ratio of 0.722 suggests substantial interaction with or derivation from continental crust. The St. Lawrence fluorite deposits occur as veins confined to and derived from the granite during the final stages of cooling.
The mid-Cretaceous succession of Orphan Knoll (northwest Atlantic): micropalaeontology and palaeo-oceanographic implications
Authors: Hart Malcolm B.
Published: April 2011

Micropalaeontological investigation of the mid-Cretaceous succession (Albian–Cenomanian) of Orphan Knoll (northwest Atlantic Ocean) has allowed direct stratigraphic comparison with successions of a similar age elsewhere in the area of the North Atlantic Ocean. The microfaunal evidence presently available suggests a major world-wide eustatic change in the mid-Cenomanian, together with associated changes in the surface water circulation of the Cretaceous North Atlantic Ocean.
On the plutonic evolution of the Wesleyville area, Bonavista Bay, Newfoundland
Authors: Jayasinghe N. R. , Berger A. R.
Published: April 2011

The Wesleyville area is composed of polydeformed gneisses and migmatites cut by a series of granitic plutons and dike suites. Four major episodes of igneous activity are recognized as follows: (1) the emplacement of the garnetiferous Powder Hill Leucogranite, marking the first event; (2) the emplacement of the large megacrystic granites of Deadman's Bay and Cape Freels; (3) development of a suite of diabase dikes; and finally, (4) the emplacement of the Newport pluton, a megacrystic granite almost identical in lithology and chemistry to the earlier ones.The country rocks were affected by five deformation episodes, of which the first two and a regional migmatization pre-dated the Powder Hill pluton. These rocks were then deformed by a third episode, and the last two events post-dated all but the diabase dikes and the Newport pluton. A 400 ± 5 m.y. whole-rock isochron date on the Cape Freels indicates that it is Devonian. This also provides a lower age limit on a late fault that apparently truncates the Newport pluton, and which locally forms the junction between the Avalon and Gander Zones.
Heavy metals in deltaic sediments of the Fraser River, British Columbia
Authors: Grieve D. A. , Fletcher W. K.
Published: April 2011

Co, Cu, Fe, Mn, Ni, Pb, and Zn, together with sand content and loss of ignition, have been determined for surflcial sediments from the Fraser River delta-front and upper foreslope. Both geochemical maps and statistical analysis disclose close relationships between trace-metal concentrations, sediment texture, and Fe and Mn content. Detailed studies of the distribution of labile and non-labile trace metals within sediments indicate that these relationships reflect increased concentrations of trace metals associated with both the detrital minerals and hydrous Fe oxides coatings in the finer fractions of the sediment. Abnormally high concentrations of labile trace metals are found on the tidal flats at two stations influenced by discharge of metal-rich sewage.
Distribution and partition of cobalt, nickel, chromium, and vanadium in the sediments of the Saguenay fjord
Authors: Loring D. H.
Published: April 2011

In the Saguenay fjord sediments, cobalt (Co) concentrations vary between 5 and 20 ppm, nickel (Ni) concentrations between 7 and 36 ppm, chromium (Cr) concentrations from 33 to 70 ppm, and vanadium (V) concentrations from 67 to 149 ppm in relation to texture and location. The highest concentrations are found in the fine-grained sediments from the upper part of the fjord and the lowest concentrations occur in the sandy sediments near the mouth of the fjord. On the average, the fjord's muds are neither greatly enriched nor depleted in Co, Ni, Cr, and V when compared to muds from the St. Lawrence estuary and the open Gulf of St. Lawrence.Acetic acid extractions indicate that 8 to 25% of the total Co, 11 to 29% of the total Ni, 2 to 9% of the total Cr, and 5 to 23% of the total V are contributed by the non-detrital fraction and may be available to the biota in the fjord. Non-detrital Co, Ni, Cr, and V appear to have been removed from solution by adsorption onto fine-grained inorganic particles and their distribution controlled by the sedimentation pattern. Non-delrital Cr, V, and Ni are also associated with Mn and Fe oxides, which are present as grain coatings. Most of the Co, Ni, Cr, and V in the detrital fraction, which accounts for 71 to 98% of the total elemental concentrations are found in sulphide, oxide, and ferromagnesian minerals. These minerals accumulate at the same rate as other detrital sedimentary material in response to the present depositional conditions.The discharge of industrial waste has not resulted in an increase in the concentrations of Co, Ni, Cr, and V in the sediments above their natural levels.
Hettangian (Lower Jurassic) rocks and faunas, northern Yukon Territory
Authors: Frebold Hans , Poulton T. P.
Published: April 2011

The Lower Jurassic Hettangian Stage is documented with certainty for the first time in the Canadian Arctic. It is represented by a basal Jurassic sandstone unit in the Bonnet Lake area of northern Yukon Territory. The two subzones of the Early Hettangian Planorbis Zone, i.e., the Planorbis Subzone and the Johnstoni Subzone, are indicated by poorly preserved Psiloceras sp. indet. and Psiloceras (Caloceras) cf. P. (C.) johnstoni (J. de C. Sowerby), respectively. The varied but poorly preserved bivalve fauna associated with P. (C.) cf. P. (C.) johnstoni includes Prosogyrotrigonia (?) sp. cf. P. inouyei (Yehara), Cardinia sp. cf. C. hybrida (J. Sowerby), C. sp. aff. C. concinna (J. Sowerby), Pleuromya (?) sp., Meleagrinella (?) sp., Oxytoma (Oxytoma) sp., and Parallelodon (?) sp. The bivalves closely resemble approximately coeval forms described from Japan. The above-mentioned faunas are figured as is a specimen of Psiloceras cf. P. erugatum (Phillips), which was previously described from the Hettangian of southern Yukon. Other occurrences of the Hettangian in Canada and Alaska are reviewed.
Silurian (Wenlockian) trilobites from Baillie-Hamilton Island, Canadian Arctic Archipelago
Authors: Perry D. G. , Chatterton B. D. E.
Published: April 2011

Wenlockian trilobites representing at least 15 genera are reported from carbonate strata within the Cape Phillips Formation, Baillie-Hamilton Island. The collections are stratigraphically bounded by the graptolite Zones of Cyrtograptus murchisoni and Monograptus testis. The fauna is generically dominated by lichids, odontopleurids, and cheirurids. Scutelluids, phacopids, dalmanitids, and harpids are notable for their absence. At the familial level the fauna corresponds to one recently discovered from similar age beds of the Mackenzie Mountains, Northwest Territories. The limited quantity and fragmental nature of much of the silicified fauna precludes erection of many new taxa, although four new species described are: Sphaerexochus dimorphus, Dicranogmus skinneri, Hemiarges rohri, and Hemiarges mikulici. Dimorphic pygidia are interpreted as probable sexual dimorphs in Sphaerexochus dimorphus n. sp.
Distribution and depositional history of sediments in Baie des Chaleurs, Gulf of St. Lawrence
Authors: Schafer C. T.
Published: April 2011

Modern sediment distribution in Baie des Chaleurs is controlled primarily by an interplay of water depth and wave climate. Modern sediment textures range from gravelly sand to silty clays. Much of the central part of the bay is covered by deposits of gravelly sand that are being reworked by wave turbulence and bottom currents. The present pattern of sedimentation started about 6000 years ago, and for about the past 5000 years, different sediment types have developed in various parts of the bay because of an interplay between tidal currents, wave-induced turbulence, and water depth. At present, this interplay is most intense in shallow nearshore environments, especially on the south side of the bay. Evidence cited elsewhere in the literature suggests that Atlantic waters may have flooded the Chaleur Trough as early as 14 000 years ago. This transgression gave way to a temporary regression about 8000 to 10 000 years ago because of a relatively rapid glacial rebound compared with the eustatic sea-level rise. A depositional pattern similar to that observed today probably occurred from 12 000 to 13 000 years B.P. but with more marine conditions than present, extending as far west as Dalhousie, New Brunswick.
A study of the dynamics of hummocky microrelief in the Canadian north
Authors: Crampton C. B.
Published: April 2011

Microrelief consisting of mounds or hummocks was examined at selected sites in the discontinuous and continuous permafrost zones of the Canadian north. Observations of the macromorphology and micromorphology of the mounds were used to interpret the dynamics of their formation. There was evidence that pressures were created inside the mounds as the freezing interface migrated towards the permafrost table during early winter. These pressures moved material inwards and upwards within the mounds, causing the plasmic lamellae and flattened quartz grains in the microfabric to rotate into a preferred alignment. Except at the most silty sites, the mounds were fractured at their centres. Subsoil spread over the surface of the sandier mounds, or the surface was severely heaved. This kind of microrelief can easily be damaged by traffic.
Oxide microstructures and the magnetic properties of Leg 37 basalts
Authors: Wayman M. L. , Evans M. E.
Published: April 2011

Samples from DSDP Leg 37 holes 332B, 334, and 335 have been subjected to magnetic and microstructural investigation. A strong, stable remanent magnetization is observed, with the high Koenigsberger ratios that are characteristic of oceanic basalts. The remanence is generally carried by dendritic s ingle-domain and (or) pseudo-single-domain oxide grains, which are homogeneous. However, thermal demagnetization in air leads to the formation of magnetite–ilmenile intergrowths not detectable by optical microscopy but clearly visible in the electron microscope. Such ultra-fine phase splitting has often been invoked as an explanation of magnetic changes observed during laboratory heating.
Sulphur isotope compositions of sulphides and sulphates, DSDP Leg37
Authors: Krouse H. R. , Brown H. M. , Farquharson R. B.
Published: April 2011

Sulphur isotope abundances were determined for 15 sedimentary and 9 basalt specimens from DSDP Leg 37 cores. Sedimentary sulphides had δ34S values as low as −54‰, which is consistent with isotopic selectivity during bacterial sulphate reduction. The δ34S values for soluble sedimentary sulphates were generally lower than ocean water sulphate. This is probably due to contributions of oxidized sedimentary sulphides. Pyrite in basalt fractures had δ34S values ranging from −33‰ to −5‰. An unique interpretation of these data is not possible at this time.
An estimate of the oxygen isotope composition of a large segment of the Canadian Shield in northwestern Ontario
Authors: Shieh Yuch-Ning , Schwarcz Henry P.
Published: April 2011

The O18/O16 ratios of the plutonic and supracrustal rocks from a large segment of the Superior province of the Canadian Precambrian Shield in Ontario (total area 111 000 km2) have been determined, using 8 composite samples prepared from 8076 individual specimens. The δO18 values (in ‰) relative to SMOW are: granitic rocks, 7.6–8.6; basic intrusive rocks, 7.2; metasedimentary rocks, 9.2; and volcanic rocks, 7.6. The composites from the granitic, basic intrusive, and volcanic rocks display δ values very similar to their contemporary or younger equivalents reported in the literature. The metasedimentary composite shows significantly lower δO18 than most Phanerozoic and Proterozoic metasediments of comparable metamorphic grades, possibly reflecting the presence of a high percentage of little-altered igneous rock detritus in the Archean sediments. The weighted average δ value (according to percent outcrop of each rock type) of this part of the Canadian Shield is estimated to be 8.1‰.
Application of L–S fabric scheme to structural mapping and paleostrain analysis
Authors: Schwerdtner W. M. , Bennett P. J. , Janes T. W.
Published: April 2011

The L–S fabric scheme, introduced by Flinn more than 10 years ago, constitutes a valuable, but largely unused tool for field geologists engaged in regional structural studies. Although there is a continuous spectrum of fabrics between pure lineation and pure foliation, Flinn defined five discrete categories, which can be readily identified in the field by experienced geologists. Several methods are available by which these field judgements may be checked. We found that there is a general tendency of overestimating the relative strength of mineral lineation and underestimating that of mineral foliation. For shape fabrics, simple geometric relations serve as safeguards in the field.Several parameters, such as Flinn's k-value, have been used to specify the strength of lineation versus that of foliation. This approach serves to quantify the L–S fabric scheme, and permits correlation between the mineral fabric and the strain ellipsoid. Relationships are most favourable where k(fabric) = k(strain). Although reliable data are scarce or still lacking, we suspect that in most metamorphic rocks k(strain) is more readily estimated than deformation magnitudes.Two examples are presented of large-scale patterns of k(shape fabric) from the Grenville Province, Ontario. In the first example, the predeformational shape of the mineral constituents is quasi-spherical, and k(fabric) presumably close to k (strain). In the second example the original shapes are inequant, and k (fabric) ≠ k (strain). But the two k-values may be close enough for qualitative comparisons between the strain patterns of the geologic structure and those of tectonic models.
Permian platycrinitid crinoids from Arctic North America
Authors: Broadhead Thomas W. , Strimple Harrell L.
Published: April 2011

Crinoid taxa based solely on parts of the stem lead to potential problems of synonymy and to nomenclatural instability. Many stem morphotypes appear to be vicarious, and homeomorphy may be common among even the most specialized appearing stems. The affinity of the crinoid stem 'genus' Platyplateium Moore and Jeffords to the camerate crinoid family Platycrinitidae is confirmed by its association with a Platycrinites-like calyx (Platycrinites nikondaense n.sp.). Platycrinites nikondaense from the Permian of Alaska and P. ellesmerense n. sp. from the Permian (Guadalupian) of Ellesmere Island represent species that have evolved by means of a secondary decrease in number of tegmen plates and modification of the stem from the Platycrinites type to the platyplateioid form. Platycrinites remotus Strimple and Watkins, from the Upper Carboniferous of Texas represents an earlier stage in tegminal evolution, but had probably already developed a platyplateioid stem.
Stratigraphy, paleogeography, and tectonic setting of the Coldbrook Group in the Caledonia Highlands of southern New Brunswick
Authors: Giles P. S. , Ruitenberg A. A.
Published: April 2011

The late Precambrian Coldbrook volcanic sequence and stratigraphic equivalents in southern New Brunswick can be divided into three distinct belts. These have been named the Eastern, Central and Western Volcanic Belts.The Eastern Volcanic Belt, along the Bay of Fundy coast, is characterized by intensely deformed mafic and felsic flows, tuffs, and abundant related volcanogenic sediments. Two thick arkosic sedimentary units in this belt reflect extensive intervals of volcanic quiescence. Fine-grained siliceous siltstone and conglomerate, locally intercalated with these rocks, have probably been derived from erosion of older Precambrian basement rocks to the northwest.The Central Volcanic Belt is composed of generally weakly deformed felsic and lesser mafic flows, and coarse lithic tuffs (including ignimbrites), and very minor intercalated sediments. The almost complete lack of water-lain sediments and presence of ignimbrites suggests subaerial deposition for most of these volcanic rocks. The relationship between rocks of the Central and Eastern Volcanic Belts is one of facies equivalence. The Western Volcanic Belt is also composed of felsic and minor mafic flows and tuffs that resemble those of the Central Volcanic Belt, but they are intensely deformed. Minor volcanogenic sedimentary rocks are intercalated with the volcanic rocks along the northwestern margin of this belt.The nature and distribution of major lithofacies belts in the Coldbrook Group and stratigraphic equivalents appear to be consistent with deposition along the margin of an intracratonic basin. It is possible, however, that further work may prove an ensialic island arc model to be a viable alternative.
Sediment and nutrient loadings to Lake Ontario: methodological arguments
Authors: Ongley Edwin D. , Ralston John G. , Thomas Richard L.
Published: April 2011

Environmental issues frequently require values for sediment and nutrient loads in river systems. Except in rare instances, such values must be drawn from existing surveillance data which may not reflect sampling strategies pertinent to the issue at hand. In particular, the time variant and nonlinear relationships between discharge and both suspended sediment and sediment-related parameters such as phosphorus cannot be captured in detail by surveillance data, Nevertheless, such data collected routinely by the Ontario Ministry of the Environment accurately reflect the relative loadings both in terms of unit and total yields in five basins where detailed suspended sediment data are available. Although surveillance data underestimate the absolute values of suspended sediment loads calculated from detailed sediment information, these data do capture the relative monthly and seasonal contributions to annual suspended sediment load. A comparison of three methods for calculating annual unit and total loadings of suspended and solute components from surveillance information indicates that annual mean data convey information which is not significantly less adequate than monthly aggregations of data.
Rb–Sr dates for granodiorite intrusions on the northeast margin of the Shuswap Metamorphic Complex, Cariboo Mountains, British Columbia
Authors: Pigage Lee C.
Published: April 2011

Whole rock Rb–Sr dates of 138 ± 12 Ma (all five whole rocks) and 163 ± 7 Ma were obtained for granodiorite stocks in Wells Gray Provincial Park, Cariboo Mountains, British Columbia. These dates bracket the biotite K–Ar date of 143 ± 14 Ma determined previously by the Geological Survey of Canada. Two biotite – whole rock ± hornblende dates of 119 ± 11 Ma and 77 ± 20 Ma indicate isotopic resetting. Initial 87Sr–86Sr ratios vary from 0.7061 ± 0.0001 to 0.7103 ± 0.0002 for rock and mineral dates.When combined with field relations, these dates restrict regional deformation and metamorphism in this area to the time interval between Upper Triassic and Upper Jurassic. The resetting event was probably Eocene, as shown in other areas along regional strike to the north and south.
Recent mollusc distribution patterns and palaeobathymetry, southeastern Beaufort Sea
Authors: Wagner Frances J. E.
Published: April 2011

Molluscs were obtained from 515 of the 657 grab samples collected 1970–1972 inclusive from southeastern Beaufort Sea, from 29 of the 46 cores taken in the area, and from raised marine deposits at Kay Point and on Herschel Island, Yukon Territory. One hundred and one species have been identified. Water depth was apparently the major factor controlling species distribution. Holocene sea levels, determined by comparing core faunas with the established depth ranges for living specimens, are considered to be reasonably accurate for near-shore sites, but yield excessively shallow water depth figures for deep stations (outer shelf and slope). The anomalous results are probably related to offshore transport of shallow water species.
Radiocarbon age of Robinson's Head moraine, west Newfoundland, and its significance for postglacial sea level changes
Authors: Brookes Ian A.
Published: April 2011

A radiocarbon date of 12 600 ± 140 years BP (GSC-2295) is reported on marine shells from sands within the Robinson's Head kame moraine at Stephen ville, Newfoundland. The moraine was deposited simultaneously with a delta-kame distal to it during a brief interval of increased ice marginal activity. This is marked at Stephenville by a temporary halt in landward marginal recession, but in some other localities around St. George's Bay by a lobate readvance into the late-glacial sea. The date refers to the time of moraine and delta-kame construction and confirms an earlier estimation. Other radiocarbon dates from the area, relating more or less closely to past sea level positions at Robinson's, south of Stephenville, are used, with an hypothetical isostatic uplift curve and a published eustatic sea level curve, to produce a first approximation to postglacial changes of local sea level in the St. George's Bay region.
Mineralogy and petrology of Quaternary lavas from the Snake River Plain, Idaho
Authors: Stout Mavis Z. , Nicholls J.
Published: April 2011

Quaternary basaltic and iron-rich flows from the Snake River Plain, Idaho, have chemical characteristics of both tholeiitic and alkali olivine basalt suites. The minerals present are olivine (Fo80–Fo44), Ca-rich augite (CaO 18 wt.%), plagioclase (An71–An40), and oxides. The spinel phases include a Mg–Al rich variety as inclusions in olivine phenocrysts. Both magnetite and ilmenite are present and temperatures estimated from the compositions of coexisting groundmass Fe–Ti oxides range from 915 to 1095 °C. Temperatures estimated from the compositions of coexisting groundmass olivine and pyroxene range from 928 to 1030 °C. Oxygen fugacities are in the expected basalt range (log [Formula: see text] values from −9.6 to −12.8). Silica activities calculated for these rocks fall in the alkali olivine basalt field but are above the Ab–Ne silica buffer.The aphyric basaltic rocks could be representative of liquids generated by partial melting (15–20%) of pyrolite. The generation of these rocks would leave a residuum of lherzolite composition. Equilibrium of the basalts with the residual composition recalculated to spinel lherzolite could occur between 15 and 25 kbar (15 × 105 and 25 × 105 kPa) at approximately 1300 °C. This is in agreement with the seismically determined depth of the low velocity zone (of partial melting) at approximately 60 km.A crystal fractionation model suggests that the porphyritic basalts are products of minor fractionation and accumulation from parental magma represented by the aphyric basalts. The iron-rich lavas (total FeO 17–18 wt.%) appear to be later stage fractionation products of the porphyritic basalts. However, basalts with approximately 14 wt.% FeO can be generated from partial melting of a model mantle.
Les chitinozoaires de la zone à Climacograptus prominens elongatus de la Formation de Vauréal (Ordovicien supérieur), Ile d'Anticosti, Québec
Authors: Achab A.
Published: April 2011

The aim of this paper is to describe the chitinozoans from the Climacograptus prominens elongatus Zone from the upper part of the Vaureal Formation (Upper Ordovician) of Anticosti Island. An emendation of the genus Hercochitina is proposed. Seven new species, Hercochitina normalis, H. minuta, H. filamentosa, H. grandispina, Conochitina baculata, C. armifera, and Ancyrochitina spongiosa are described.The microfauna characterized by the dominance of Hercochitina, is distinctive and does not resemble those reported from elsewhere.
Geomorphological conditions of gabbro weathering at Mount Megantic, Quebec
Authors: Clément P. , Kimpe C. R. De
Published: April 2011

Chemical and mineralogical analyses of a deeply weathered gabbroic rock showed that smectite (nontronite) is the main secondary mineral in association with iron-rich chlorite. The granular disintegration of the rock is mainly induced by the alteration of ferromagnesian minerals. The occurrence of silica-rich minerals is explained by the confining conditions imposed by the depressed topography of the site; along steeper slopes gibbsite is found in thinner saprolites. Weathering, though still proceeding, must have started before the last glaciation in order to explain the thickness of the profile; this is also supported by geomorphological considerations. The succession of erosion and weathering stages during Pleistocene times contributed to the shaping of the gabbroic depression.
Stratigraphy and structure of the Kootenay Arc in the Riondel area, southeastern British Columbia
Authors: Höy Trygve
Published: April 2011

The succession of metasedimentary rocks in the Riondel area is correlated with a Hadrynian–Cambrian sequence established in the Duncan Lake area to the north and the Salmo area to the south. The succession includes phyllite, schist, and quartz-pebble conglomerate of the Horset hie f Creek Group; quartzite, siltstone, and schist of the Hamill Group; calcareous schist of the Mohican Formation; and a prominent marble, the Badshot Formation. The youngest metasedimentary rocks include para-amphibolite, calc-silicate gneiss, and pelitic schist of the Lardeau Group.A lower Paleozoic succession of metasedimentary locks in the western part of the Riondel area forms a large overturned panel which is the lower limb of a phase 1 recumbent anticline, the 'Riondel nappe'. The root zone of the nappe is inferred to lie beneath a west-dipping reverse fault, the 'West Bernard fault', which separates the inverted panel of rocks on the west from the right-way-up panel in the east. Tight to isoclinal north–south trending phase 2 folds with upright to west-dipping axial surfaces and sub-horizontal fold axes are superposed on the Riondel nappe. Small-scale, south westerly trending phase 3 warps and open folds are overprinted on the limps of the older folds.The age of the Riondel nappe cannot be positively determined. It is assumed to have developed during the Caribooan orogeny in Devono-Mississippian (?) time and subsequently to have been deformed by phase 2 folding and associated faulting in middle Jurassic to early Cretaceous time.
Deformational characteristics of experimentally deformed Adirondack anorthosite
Authors: Seifert Karl E. , Verploeg Alan J.
Published: April 2011

The dominant mode of deformation for anorthosite deformed experimentally at temperatures from 400 °C to 1000 °C and confining pressures from 5 to 17 kbar (5 × 105–17 × 105 kPa) at a constant strain rate of 8 × 10−5 s−1 is cataclasis, although plastic flow occurs abundantly at temperatures of 800 °C or above. The amount of plastic flow increases rapidly as temperature is increased. An anorthosite sample (AW14) containing abundant alteration prior to testing shows a further increase in alteration during testing, and is weak at temperatures of 800 °C or greater compared to an unaltered anorthosite sample (TL3), although their strength is similar below 800 °C. Some plagioclase in sample TL3 converted from the original low or low transitional structural state to a high or high transitional state during testing at 800 °C or above. Albite and pericline twins and deformation lamellae produced during tests concentrate in the regions of cores showing structural conversion, and are most common at temperatures of 800 °C or greater. The distribution of both alteration and structurally converted plagioclase produced during testing appears to be related to temperature gradients within cores.
Geomagnetic sounding near the northern termination of the Appalachian System
Authors: Cochrane N. A. , Wright J. A.
Published: April 2011

A general survey of geomagnetic induction phenomena in Newfoundland is undertaken. The northeastward extension of the 'Atlantic' conductivity anomaly can be traced into southwestern Newfoundland where it is lost in intense conduction–induction effects due to the channeling of shallow water electric currents about the projecting corner of southeastern Newfoundland. Shallow water induction processes in the Gulf of St. Lawrence are better clarified. Evidence is presented for a tentative inland conductivity anomaly in eastern Newfoundland where geological evidence points to an ancient zone of subduction.
Seismic profiling in Miramichi Bay, New Brunswick
Authors: Howells K. , McKay A. G.
Published: April 2011

A combined echo sounder and seismic profiling survey in Miramichi Bay has detected two prominent seismic reflectors. The upper reflector probably represents a marine terrace, above which are recent sediments. The sea bed consists mainly of sands in the barrier island and Outer Bay area, whereas the Inner Bay consists mainly of sandy muds and muds. A discontinuous 'gas' reflector in the muds of the Inner Bay masks all deeper seismic reflectors where it is present. The lower seismic reflector is probably the Pennsylvanian bedrock surface. Between the upper and lower reflectors, proglacial sediments and glacial till are probably present. The bedrock surface has been eroded into deep, linear channels by a pre-Pleistocene drainage system which may have been subsequently overdeepened by glacial scouring. These channels may have been eroded along lines of weakness in the Carboniferous sediments representing structures, such as joints, fractures, or faults in the bedrock. These structures may be related to the extension of the Catamaran Fault Zone in the pre-Carboniferous basement rocks beneath Miramichi Bay.
The petrogenesis and origin of the analcime in the volcanic rocks of the Crowsnest Formation, Alberta
Authors: Ferguson L. J. , Edgar A. D.
Published: April 2011

The Crowsnest Formation consists of trachytes, analcime phonolites and blairmorites, metamorphosed to zeolite facies. The latter rocks contain large analcime phenocrysts variously suggested as being of primary igneous origin or due to transformation from original leucite by reaction of Na-rich fluids. Although neither field relationships or petrography provide convincing data favouring either hypothesis, the presence of primary undisrupted inclusion trails in the analcime tend to support the former hypothesis. Compositions of the analcimes differ from that of an analcime formed by transformation from leucite. The chemistry of the rocks and their constituent pyroxenes are consistent with a sodic rather than a potassic differentiation trend; feldspar and garnet analyses support this conclusion. Oxygen isotope values for the pyroxenes indicate no extensive exchange with a low temperature fluid. Thus it seems unlikely that leucite was ever a constituent of the Crowsnest suite as necessitated by the hypothesis of transformation from leucite. Geochemistry and known experimental data indicate that the analcime phonolites and blairmorites differentiated from a trachytic magma under restricted conditions at depths greater than 25 km by early sanidine and later analcime fractionation. The parental trachyte may be produced by partial fusion of crustal material at depths greater than 35 km.