bluuebunny/crossref_metadata_2025 huggingface dataset:
The 1981 – 1982 surge of Hazard Glacier, Yukon Territory
Authors: Clarke Garry K. C. , Collins Sam G.
Published: November 2010

A surge of Hazard Glacier, believed to have started in 1981, displaced ice as much as 0.7 km. Before the surge, ice thickness was measured by radio echo sounding and temperatures were taken in three holes to the glacier bed. The glacier is subpolar with 10 m temperatures near −5.4 °C, and temperature versus depth profiles show many anomalous features. We attribute these anomalies to various effects of past surges and to ablation at the upper surface. The interpretations are supported by simple calculations derived from dimensional analysis. Part of the glacier is warm based: at two sites the basal temperature was at the melting point; at the third site, upstream from the others, it was −2.70 °C.
Paleomagnetism of the Mudcracked formation of the Precambrian Little Dal Group, Mackenzie Mountains, Northwest Territories, Canada
Authors: Park John K.
Published: November 2010

A previous study detailed the paleomagnetism of red limestones of the Little Dal Group Basinal assemblage, but failed to prove whether the magnetization carried by the red pigment was prefolding. The present study on "red" sandstones of the immediately underlying Mudcracked formation, using acid leaching at three sites, revealed a paleomagnetic direction B in the pigment (266°, −17°; seven samples; k = 28; α95 = 12°), which closely agrees with the probable pigment direction of the Basinal assemblage (273°, −09°; 12 sites; α95 = 11°). Since a fold test of the B sample directions is significant at the 95% probability level, I suggest that the pigment in both units is prefolding (pre-Paleocene at latest).
Origin of radioactive barite sinter, Flybye springs, Northwest Territories, Canada
Authors: Cecile M. P. , Goodfellow W. D. , Jones L. D. , Krouse H. R. , Shakur M. A.
Published: November 2010

Cold springs emerging a long the contact between Devonian limestone and shale units in the northwestern Canadian Cordillera are presently depositing a radium-enriched barite sinter. A geological cross section through the springs area shows that groundwaters could circulate through a mainly limestone aquifer to depths of approximately 2 km. Some shales and volcanic rocks associated with the aquifer contain: barium, bound in feldspars; barite, pyrite, and organic matter hosted in shale; and radium in feldspars or produced by the radioactive decay of uranium associated with organic matter hosted in shale. Spring waters are of the [Formula: see text] type characteristic of water that has equilibrated with clay minerals. A subsurface equilibration temperature of 34 °C was determined by silica geothermometry, and 31 °C by magnesium-corrected Na+–K+–Ca2+ geothermometry. Emerging waters are partly mixed with surface runoff and therefore these temperatures represent only minimum values. Assuming a normal geothermal gradient these temperatures indicate minimum groundwater percolation depths of 1 km. The δ34S values of barite sinter samples and one sample of aqueous sulphide range from + 15 to + 23‰, indicating a marine sedimentary rock source for sulphur. The corresponding δ18O values are negative, implying that the bulk of the sulphate oxygen is derived from groundwater during sulphide oxidation. These data suggest that the springs are fed by groundwaters that have percolated to depths of as much as 2 km, passing through an aquifer of Paleozoic marine sedimentary rocks and volcanic rocks. At depth these waters were reducing and probably weakly acidic. They dissolved barium, sulphur, and radium, which were transported to the surface where the water quickly oxidized and precipitated Ba(Ra)SO4.
Regional cross section of the Southern Province adjacent to Lake Huron, Ontario: implications for the tectonic significance of the Murray Fault Zone
Authors: Zolnai A. I. , Price R. A. , Helmstaedt H.
Published: November 2010

The Southern Province in the Lake Huron area of Ontario, and the Penokean Fold Belt of Minnesota, Wisconsin, and Michigan have the earmarks of a collisional orogen. The Huronian Supergroup, a southerly facing passive margin sequence, was deposited during early Aphebian (Early Proterozoic) crustal stretching (and ocean basin formation?) along the southern margin of the Superior Province Archean craton. It accumulated as four unconformity-bounded, northerly tapering, onlapping clastic wedges (megacycles). The thickness and facies variations reflect syndepositional down-to-the-basin (south) normal faulting that controlled the accumulation and preservation of the lower three Huronian megacycles. These are overlapped northward by the youngest megacycle, an extensive sheet of clastic sediments recording post-stretching regional subsidence of the cratonic margin due to cooling and thermal contraction. Soft-sediment folds in the rocks of the youngest megaycycle to the extreme south probably indicate southward slumping into an adjacent basin. Nipissing diabase instrusions, 2100 Ma old, cut Huronian strata and soft-sediment folds.An enigmatic episode of compressional deformation is dated by 2333 Ma old plutons. During the first ductile (penetrative cleavage and peak metamorphism) phase of the Penokean Orogeny (ca. 1900 Ma), the thicker part of the Huronian supracrustal wedge was overridden and depressed to mid-crustal levels, presumably because it was overridden by an allochthonous terrane, the remainder of which is postulated to lie south of the Manitoulin Island Discontinuity. The early down-to-the-basin normal faults were reactivated and became the loci of north-verging, listric reverse faults. The thick wedge of Huronian rocks south of the Murray Fault Zone, which was deformed and metamorphosed as it was carried down to mid-crustal levels, subsequently was thrust northward over a thinner sequence of Huronian rocks that apparently was never deeply buried. Concurrently, the edge of the Superior craton and its cover of Huronian deposits were compressed as thrusting propagated northward and eventually deformed the 1850 Ma old Sudbury Nickel Irruptive. Structures that formed in the thick part of the wedge during the ductile deformation were rotated during the thrusting to their present near-vertical position. Late or post-Penokean brittle deformation marked by conjugate small strike-slip faults reflects continued or renewed north–south compresssion in an isostatically rising foldbelt, and post-Penokean right-lateral strike slip along the Murray Fault Zone is probably related to northwestward compression during the Grenville (approx. 1000 Ma) Orogeny.
U–Pb zircon ages and the evolution of the Michipicoten plutonic–volcanic terrane of the Superior Province, Ontario
Authors: Turek A. , Smith Patrick E. , Schmus W. R. Van
Published: November 2010

The Archean Michipicoten greenstone belt of the Superior Province in Ontario is made up of supracrustal rocks divided into lower, middle, and upper metavolcanic rocks with associated metasedimentary rocks. The belt has been intruded by granitic rocks and is also surrounded by granitic terranes. Based on U–Pb zircon geochronology it appears that volcanism in the area extended from at least 2749 to 2696 Ma, and plutonism and tectonic activity extended from at least 2888 to 2615 Ma. The various granitic (and also one gabbroic) plutons, both internal and external to the greenstone belt, were emplaced concomitantly with the three volcanic cycles as well as before and after the formation of the volcanic rocks. Zircon ages reported here, together with previously published ages, show that the area evolved in six major volcanic and plutonic events: (I) 2888 Ma—plutonism, (II) 2743 Ma—volcanism and plutonism, (III) 2717 Ma—volcanism and plutonism, (IV) 2696 Ma—volcanism and plutonism, (V) 2668 Ma—plutonism, and (VI) 2615 Ma—plutonism. The oldest rock dated at 2888 ± 2 Ma belongs to the external granitic terrane and may be basement to the supracrustal rocks.
Simulation of the August 1979 sudden discharge of glacier-dammed Flood Lake, British Columbia
Authors: Clarke Garry K. C. , Waldron David A.
Published: November 2010

In August 1979 a glacier outburst from Flood Lake, British Columbia, released 150 × 106 m3 of water. The resulting flood was routed through the Stikine River and yielded a maximum discharge rate of 1200 m3 s−1 at a gauging station 90 km downstream from the glacier dam. We have used a computer model to simulate this outburst in order to test the usefulness of the model as a predictor of flood magnitude. The predicted peak discharge is 2160 m3 s−1 at the outlet tunnel of the ice dam and 1700 m3 s−1 at the gauging station.
Isotopic composition of lead in galena and Ni-arsenides of the Midwest deposit, northern Saskatchewan
Authors: Cumming G. L. , Krstic D. , Worden J. M. , Baadsgaard H.
Published: November 2010

Pb-isotope ratios from galenas and Ni-arsenides of the Midwest deposit indicate that there are three classes of Pb present. The first, with 206Pb/204Pb ratios of about 22.5 and 208Pb/204Pb ratios of about 43.5, occurs only in galenas and is restricted to the basal Athabasca Formation. The second occurs from about 35 m above the unconformity to the deepest samples available to us (60 m into the basement rocks). Characteristically the 206Pb/204Pb ratios are 30–35 and the 208Pb/204Pb ratios are about 50, and this Pb occurs in both galenas and Ni-arsenides. The third class has elevated 206Pb/204Pb ratios ranging up to 350 and occurs within about 10 m of the unconformity in close association with U minerals.A model is developed in which radiogenic additions to galena have occurred during at least two different events. The first added U and Th daughters to "sandstone-type" Pb at 265 ± 50 Ma, and the second added U daughter only to the "basement-type" Pb in the past 50 Ma or less. These events are consistent with Pb loss recorded in the U minerals and indicate that the lead-loss mechanism from these U minerals is catastrophic rather than continuous diffusion.Some trace Pb isotopic compositions in Ni-arsenides suggest to us the occurrence of disequilibrium migration of 238U daughter products, but there is no clear evidence that this occurred on a macroscopic scale in the galena.The model implies that some galena predates the U mineralization, and thus that there is a potential for Pb–(Zn?) mineralization in the basal Athabasca Formation.
Heat flow in a back-arc environment: Intermontane and Omineca Crystalline belts, southern Canadian Cordillera
Authors: Davis Earl E. , Lewis Trevor J.
Published: November 2010

A suite of 20 heat flow measurements has been completed across the Intermontane and Omineca Crystalline belts in south-central British Columbia at about 50°N. Values along the 200 km line are high (83 mW m−2, corrected for Pleistocene glacial climate; reduced heat flow is 67 mW m−2) and uniform (standard deviation = ± 10%). There appears to be no difference in the thermal structure of the two geologic belts. Two sources of heat are considered to explain the level of heat flow observed: a discrete thermal event in the Eocene, and a steady-state supply of heat maintained in the back-arc location by asthenospheric flow caused by nearby subduction. Both can account equally well for the elevated heat flow observed. However, in light of seismic, magnetic, electrical, and flexural data that suggest that the lithosphere may be as thin as 30–40 km, it is concluded that a steady supply of heat must exist since this thickness is much less than the thickness of lithosphere that would be present 50 Ma after even a major thermal event.
Chemical composition of Archean Pontiac metasediments, southwestern Abitibi Belt, Superior Province
Authors: Ujike Osamu
Published: November 2010

Three mica schists from the Pontiac Group have a La/Yb ratio of ~19, a La content of ~32 ppm, and a Th content of ~6 ppm. These values are higher than those of the average Archean upper crust (La/Yb, ~7; La, ~13 ppm; Th, ~3.5 ppm) and the mean compositions of Blake River (La/Yb, ~2.6 (184 analyses); La, ~10 ppm (184 analyses); Th, ~1.3 ppm (143 analyses)) and other subalkalic volcanic groups in the Kirkland Lake–Noranda region. Hence it is unlikely that the latter are exclusive sources of Pontiac detritus. The chemical data reveal that Timiskaming-type alkalic rocks (La/Yb, ~ 45; La, ~95 ppm; Th, ~21 ppm (means of 29 analyses)) are likely contributors to Pontiac metasediments. However, the Timiskaming Group itself is generally considered to be younger than the Pontiac Group. This implies the presence of an undetected or unpreserved terrane characterized by Timiskaming-type alkalic rocks.
Pillow formation and layered flows in the Circum-Superior Belt of eastern Hudson Bay
Authors: Baragar W. R. A.
Published: November 2010

Detailed sections mapped across well exposed Aphebian tholeiitic and komatiitic flow assemblages on the islands of eastern Hudson Bay afford an insight into mechanisms of pillow development. Most of the flows with distinguishable boundaries are pillowed in their lower parts and massive in their upper parts. Pillow tubes are envisaged as developing, therefore, at the thin leading edge of a flow; as the volume.of flow is thus choked the lava behind overrides the impediment and repeats the process farther forward. Continued repetition of tube formation at flow fronts and the subsequent overriding or diversion of advancing lava result in formation of a carpet of pillow tubes over which the massive, flowing lava meanders in the manner of a prograding river. When lava production declines or ceases, lava streams and trapped ponds distributed over the surface of the pillow mat freeze into the massive tops observed in section.Layered flows are a development of the same process, illustrated in this paper by the Hudson's Bay layered flow. In this flow, a massive top thickens from 20 to 75 m over a lateral distance of 200 m as a result of damming behind a pillow barrier of its own making. Subsequent spills of lava over the pillow dam increased its height until the drainage, adapting to the new topography, aligned itself parallel to the barrier and flowage resumed along the thickened lens thus created. Accompanying flow differentiation formed an olivine-rich zone suspended above and conforming to the shape of the base of the massive lens.
Late glacial and postglacial geology in the Lake Ontario basin
Authors: Sly P. G. , Prior J. Wyn
Published: November 2010

Western Lake Ontario sediments record a till–mud–till sequence over bedrock and a thick layer of partly distorted glaciolacustrine clay unconformably overlying this. Another unconformity separates this clay from younger fine (lacustrine?) deposits, which are also distorted. Modern foreset and bottomset beds of the Niagara River overlap the lacustrine and glaciolacustrine deposits.In eastern Lake Ontario, thick glaciolacustrine clays overlie bedrock and the infilling ice-marginal deposits. These glaciolacustrine clays are severely distorted, and in the deepest parts of the area patches of overlying lacustrine (?) clay are preserved. A distorted terracelike deposit is preserved at higher elevation in the St. Lawrence trough. Bedrock, lag gravels, and sandy deposits characterize shallow-water areas.We suggest that after the fall of lake levels in the Lake Ontario basin, during the post-Iroquois lake phases, glaciolacustrine clays were subject to distortion by ice action at the time of the Greatlakean stadial. This deformation was more severe at the east end of the basin. At its lowest level, the surface of early Lake Ontario following the post-Iroquois phases was below the present lakebed in much of western Lake Ontario. Ice-wedge casts formed in sediments at both ends of the basin, soon after the initiation of early Lake Ontario, and are correlated with the Algonquin (St. Narcisse) glacial phase. Whereas there are significant accumulations of modern mud in the western basin of Lake Ontario, in the Kingston basin there is little except in the St. Lawrence trough.
Bio- and aminostratigraphy of some Quaternary marine deposits in West Greenland
Authors: Funder Svend , Simonarson Leifur A.
Published: November 2010

14C dates and the geological setting of Quaternary marine deposits from three sites in West Greenland indicate a pre-Holocene age. The mollusc faunas at the sites are distinctly different, although all reflect influx of some subarctic water into Baffin Bay. The fauna from Patorfík is the most diverse subfossil Quaternary fauna known from Baffin Bay. Such species as Panopea norvegica and Balanus hameri indicate conditions warmer than the present, although no identical faunal assemblages are known. The fauna at Laksebugt is similar to modern faunas, but the dominating Portlandia arctica and Macoma moësta indicate a climate somewhat colder than the present, and Mytilus edulis suggests the presence of subarctic water. The fauna from Mudderbugt is reworked, but the presence of Chlamys islandica indicates that conditions were not entirely different from the present.Amino-acid analyses on shells from the three sites place them in three distinct aminozones, with Patorfík as the oldest and Laksebugt the youngest. Age estimates using this and geological and biological evidence suggest that the Laksebugt aminozone dates from the isotopic stage 5–6 transition (130 ka). The Patorfík aminozone is probably of mid- or early Quaternary age (235–1800 ka).Correlation with the few previously known pre-Holocene marine deposits of western Greenland implies that only one period of extensive glaciation can be recognized during the Weichsel (Wisconsin) glaciation.
Evolution of P–T conditions during a high-grade metamorphic event in the Maniwaki area (Grenville Province)
Authors: Indares A. , Martignole J.
Published: November 2010

Pelitic and basic rocks of the Grenville Supergroup in the Maniwaki area (100 km north of Ottawa) were selected for a detailed investigation of the metamorphic history of the Central Metasedimentary Belt of the Grenville Province.Mineral assemblages suggest metamorphic conditions of the granulite facies with local and irregular persistence of the amphibolite facies. Chemical analysis of minerals reveals a lack of equilibrium on the thin section scale. Systematic variation of mineral compositions is explained as the net result of several mineral equilibria established at different stages during the metamorphic evolution of the area. Peak temperatures obtained by biotite–garnet thermometry (cores of isolated grains) are between 760 and 860 °C, whereas clinopyroxene–garnet thermometry gives 740–820 °C. Retrograde temperatures as estimated by various thermometers range between 550 and 750 °C (biotite–garnet), 498 and 670 °C (cordierite–garnet), and 690 and 720 °C (clinopyroxene–garnet). Peak pressures were 6.5–8.5 kbar (650–850 MPa) based upon the ga–pl–sil–qtz barometer and the cpx–ga–pl–qtz barometer. Retrograde pressures of 3.5–5.5 kbar (350–550 MPa) (ga–pl–sil–qtz), 4.1–5.2 kbar (410–520 MPa) (cd–ga), and 5.7–7 kbar (570–700 MPa) (cpx–ga–pl–qtz) were determined.A compilation of results in a P–T diagram allows us to construct a retrograde gradient convex towards the T axis, with an average slope of 12 bar/°C (1.2 MPa/°C). This curve suggests fast uplift and erosion just after the peak of metamorphism followed by a long cooling stage accompanied by minor uplift.
Application of till pebble lithology to the differentiation of glacial lobes in southern Alberta
Authors: Shetsen I.
Published: November 2010

Variations in the pebble composition of surface till in southern Alberta indicate the presence of three contemporaneous lobes in the last continental glacier. The ice lobe domains have similar pebble associations and differ only in the frequency of occurrence of rock constituents. A large part of the percentage variability within each domain is caused by irregular entrainment of locally derived stones, which dilutes pebble contents and results in a lithology substantially different from the provenance composition. The study has shown that the regional trends are preserved and can be recognized in the locally modified lithologies, but the latter have to be isolated and evaluated differently from the regular provenance lithologies. The common diluting agent in the area is fluvial gravel that is widespread on erosional bedrock surfaces and in preglacial valleys. Because the gravel is generally coarse, pebble fractions of larger size are more affected by local dilution than are successively finer fractions. Quantitative comparison of rock contents in two size ranges helps to identify the regional and local types of pebble composition and to segregate petrological data into two corresponding sets. Source indices are calculated then as a function of three lithologic variables, for each of the sets separately. The indices have similar values in nondiluted and diluted samples of a given area and distinguish well between tills deposited by glaciers with different directions of regional flow.
The origin of compositional variation in basalts recovered by submersible drill from Mount Glooscap, Mid-Atlantic Ridge at 36°25′N
Authors: Walker James A. , Ryall Patrick J. C. , Zentilli Marcos , Gibson Ian L. , Dostal Jarda
Published: November 2010

A large peak in the crestal mountains of the Mid-Atlantic Ridge, about 16 km west of the AMAR rift valley at 36°25′N, was sampled for basalt with a submersible electric rock core drill on a comparable surficial scale as the FAMOUS area. Twenty-eight basalt samples from seven drilling stations have been analyzed for major and trace elements. Many of the samples come from flows lying under a cover of carbonate rocks and therefore could not have been sampled by a submersible or a dredge.Through comparisons with published compositional data, it appears that, unlike "FAMOUS-generated" basalts, "AMAR-generated" basalts are, on average, more evolved and are always LREE enriched. Most of the in- and between-hole compositional variation can be accounted for by low-temperature alteration, accumulation of phenocrysts, and low-pressure, relatively low-temperature fractional crystallization. A source heterogeneous in trace elements or undergoing variable degrees of partial melting is necessary to explain the remaining compositional variation. If the large peak can be interpreted as a single volcano, it may be that lavas become progressively more differentiated with time at mid-ocean ridge volcanoes as they commonly do at subduction zone volcanoes.
Subsidence of a guyot west of Flores, Azores
Authors: Lambeck Kurt
Published: November 2010

The analysis of mechanisms of subsidence of seamounts is often limited by inadequate information on the age of the seamount at the time it was first eroded to sea level. The ages of carbonates deposited on the eroded surface and the ages of the basalts therefore provide valuable observations for evaluating subsidence models. Such ages were recently reported for a small seamount in the Azores. It was found that the resulting subsidence was 100–150 m greater than could be attributed to thermal contraction of the ocean floor. This discrepancy can be attributed to stress relaxation within the underlying lithosphere. Viscoelastic models predict a subsidence that is a function of the effective relaxation time τ and the effective flexural rigidity D. Consistent parameters for 5–10 Ma old lithosphere are [Formula: see text] and [Formula: see text].
A new mid-Ludlow graptolite faunule from northern Yukon, Canada
Authors: Lenz A. C.
Published: November 2010

A probable mid-Ludlow graptolite faunule is described from the central Richardson Mountains, northern Yukon: The faunule contains Bohemograptus bohemicus tenuis, ?Bohemograptus sp., Pristiograptus cf. haupti, Monograptus uncinatus?, and ?Neodiversograptus sp. The faunule is distinctive in that a multibranched taxon, tentatively identified as Neodiversograptus, is present.
Focal depths and source parameters of the Rocky Mountain House earthquake swarm from digital data at Edmonton
Authors: Rebollar C. J. , Kanasewich E. R. , Nyland E.
Published: November 2010

Seismic records at Edmonton (EDM) and Suffield (SES) between January 1976 and February 1980 show 220 events with magnitudes less than 4 originating near Rocky Mountain House. Many of these events show well defined Sn, Sg, and Pg phases and a small variation in the difference of Sg − Sn and Sg − Pg. Analysis of the theoretical travel times using a structure determined for central Alberta yields an average focal depth of 20 ± 5 km and an average epicentral distance of 175 ± 5 km southwest of Edmonton for 40 of these events. Because Sn was not clear on the remainder, it was not possible to get focal depths for all the events.Seismic moments of 80 events with local magnitudes from 1.6 to 3.5 were found to be in the range of 6.6 ± 2 × 1018 to 7.9 ± 2 × 1020 dyn∙cm (6.6 ± 2 × 1013 to 7.9 ± 2 × 1015 N∙cm). A relationship between local magnitude and seismic moment was log (M0) = 1.3ML + 16.6. This is similar to that determined for California. Source radii, where they could be determined, were 500 ± 50 m and stress drops were 0.75 ± 0.75 bar (75 ± 75 kPa).The energy release of 263 events recorded at EDM from the Rocky Mountain House area was 5.6 × 1017 erg (5.6 × 1010 J). The b value for this earthquake swarm was 0.8, similar to that observed in other parts of western Canada.The depths of focus, the low stress drops, and the statistical similarity to other natural earthquake sequences suggest that at least part of the swarm is of a natural origin.
The Gang Ranch – Big Bar area, south-central British Columbia: stratigraphy, geochronology, and palynology of the Tertiary beds and their relationship to the Fraser Fault
Authors: Mathews W. H. , Rouse G. E.
Published: November 2010

Tertiary rocks in the Gang Ranch – Big Bar area, south-central British Columbia, consist of (1) Early or Middle Eocene (50 Ma) lavas, breccias, and tuffs capped by a mappable unit of conglomerate and clays, totalling 1600 m in thickness; (2) Early Miocene basalt and obsidian, only locally present on high summits; (3) Mid-Miocene gravels and tuffs estimated to be up to 300 m thick; and (4) Pliocene "plateau basalts" up to 130 m thick, locally underlain by fluvial and lacustrine sediments. A rich, probably subtropical, palynoassemblage supports the correlation of the first unit with the Kamloops Group of south-central British Columbia, and the palynomorphs from unit (3) indicate equivalence with the Fraser Bend Formation of the Quesnel area.The northwest-trending Fraser Fault transects the area. Eocene and underlying mid-Cretaceous beds are confined to the west side of the fault; Triassic metasediments and metavolcanic rocks form the east wall. The west side of the fault has been structurally lowered by at least 1.6 km in Eocene and(?) later time. Some 70 km of dextral displacement since mid-Cretaceous time is suggested but is not unequivocally demanded. Major movement has occurred since and possibly during deposition of the Eocene beds. Pliocene beds overlying the fault and Mid-Miocene beds adjacent to the fault trace are apparently undisturbed.Pliocene drainage appears to have been northward. Slight northerly tilting has occurred since, but notwithstanding this the southward-flowing Fraser River has become established here. Glacial diversion of an earlier drainage pattern is suspected.
The genus Kassabiana Salaj, 1983, from the uppermost Maastrichtian of northeastern Tunisia
Authors: Salaj Joseph , Solakius Nikolaos
Published: November 2010

The genus Kassabiana, established by Salaj as a member of the family Globotruncanidae Brotzen, 1942, is discussed in detail. In addition to a detailed diagnosis and remarks, the second member of the genus, Kassabiana falsocalcarata trigonocamerata subsp. nov., found in the uppermost Maastrichtian at Enfidaville, northeastern Tunisia, is presented.
Petrographic examination of low-rank coals from Saskatchewan and British Columbia, Canada, including reflected and fluorescent light microscopy, SEM, and laboratory oxidation procedures
Authors: Dobell P. , Cameron A. R. , Kalkreuth W. D.
Published: November 2010

The response to oxidation of eight coals of lignite and subbituminous rank from Saskatchewan and Hat Creek, British Columbia, was studied by means of maceral distribution, fluorescence, and scanning electron microscopy (SEM). The oxidizing agent used was Schulze's solution, with some modification of reaction time from that normally employed in palynological maceration. These eight samples were chosen to represent different macroscopically described lithotypes. Maceral analysis indicates that the huminite macerals behave differently when oxidized. Densinite seems to be the most susceptible to destruction, along with gelinite. Humotelinite (eu-ulminite and texto-ulminite) is more resistant and in four of the eight samples shows a slight increase in concentration. Oxidation increases the relative content of liptinite along with some of the inertinite macerals (fusinite and semifusinite). Among the liptinite macerals resinite appears to be preferentially concentrated, suggesting that the modified oxidation procedure is not rigorous enough to enrich spore and pollen concentrations. The Hat Creek samples showed a variety of resinites that could be differentiated into four types under fluorescence conditions by comparison of colour, by wavelength of maximum fluorescence intensity, and by different red/green quotients. The SEM provides a technique not normally used to examine the morphological features of macerals. Many of these features are enhanced by the employment of this technique, and its use with oxidation residues extends our ability to observe the microscopic properties of macerals.
Mise en évidence d'une erreur de fossilisation du champ magnétique terrestre dans un dépôt actuel
Authors: Biquand Daniel
Published: November 2010

We present a study of the remanent magnetization of the so-called "ocres d'Apt" clayey sediment, resulting from an artificial sifting carried out industrially for obtaining pigments. Our investigation concerned 172 specimens of several hundred of cubic centimetres, corresponding to a sampling distributed over the whole area of four basins (approximately 600 m2) and 10 m along the axis of a channel. We show that the main carrier of the magnetization is hematite and that the primary magnetization is a detrital one. An extremely moderate thermal treatment (<88 °C) erases the intense viscous magnetization acquired since the sampling (10 years) but preserves a weak component of a primary magnetization, a differential analysis of which (comparison between sites), as well as laboratory drying experiments, shows that it was acquired before the complete drying out of the clay and that its direction is not modified, either by currents that existed during some phases of the sedimentation, or by the final drying out. The intrasite mean direction of the primary magnetization is approximately identical for three of the basins and for the channel, with a zero difference in declination with, but with an inclination that is 16 °shallower than, that of the Earth's magnetic field. As for the fourth basin, the declination coincides with, but the inclination is 13 °higher than, that of the field.
Archaeotrypa Fritz, 1947 (Cambrian, Problematica) reinterpreted
Authors: Kobluk David R.
Published: November 2010

Detailed petrographic analysis of the type specimens of Cambrian Archaeotrypa prima and A. secunda shows that A. prima differs in important features from the original description. The tubes that make up the compound skeleton are twice as wide as thought previously, with an internal structure comprising both straight and zigzag longitudinal partitions and flat transverse partitions; the transverse partitions are staggered in vertical section and meet the zigzag longitudinal partitions. Archaeotrypa secunda differs very significantly from A. prima. The holotype of A. secunda is very poorly preserved, and consists of only a small tangential section comprising six complete and seven incomplete polygons. The genus Archaeotrypa and the species A. prima are retained, but the name A. secunda is restricted to the type specimen. The affinity of Archaeotrypa prima is uncertain, but it may be modeled as a cystoporate bryozoan or alternatively as an echinoderm.
Trace-metal geochemistry of sediments from Baffin Bay
Authors: Loring D. H.
Published: November 2010

The major- (Si, Al, Ti, Fe, Mn, Ca, Mg) and trace-metal (Zn, Cu, Pb, Co, Ni, Cr, V, Li, Cd, Hg) compositions of surficial sediments from Baffin Bay and the sounds (Lancaster, Jones, Smith) leading into the Arctic Ocean have been determined. The sediment composition varies regionally and in response to textural variations and the heavy-metal concentrations are at or near natural levels in relation to their source rocks and other uncontaminated shelf and oceanic sediments.Chemical partition indicates that most of the heavy-metal concentrations (80–99%) except for Cd (27–71%) are derived from various sulphide, oxide, and silicate minerals. The host minerals are predominantly fine grained and have accumulated at the same rate as other detrital clastic material of comparable grain size. As a result, the highest trace-metal concentrations occur in the fine-grained sediments occupying the deepest parts of the sounds and Baffin Bay. Although most of the metals have reached their depositional site by water transport, a small but significant amount has probably been ice rafted to the offshore areas, especially in the northern part of the bay. Only small amounts of the total metal concentrations (1–20%) except Cd (29–73%) are present in the nondetrital fraction. Although difficult to locate exactly, the metals in this fraction appear to reside in ion-exchange positions and in amorphous iron grain coatings and are weakly bound to fine-grained organic matter.Overall, the physical–chemical sedimentological conditions including ice movements are responsible for the dispersal and deposition of fine-grained inorganic and organic matter and for the control of the abundance and distribution of trace metals in this part of the eastern Canadian Arctic.
Early Devonian conodonts from Prince of Wales Island, southeastern Alaska
Authors: Savage Norman M. , Gehrels George E.
Published: November 2010

Early Devonian conodonts from 11 localities on Prince of Wales Island and adjacent small islands, southeastern Alaska, include Pandorinellina optima (Moskalenko), Pandorinellina exigua philipi (Klapper), Pandorinellina exigua exigua (Philip), Pandorinellina? boucoti (Klapper), Pelekysgnathus serratus Jentzsch, Pelekysgnathus cf. P. klamathensis Savage, Pelekysgnathus n. sp., Eognathodus sulcatus sulcatus Philip, Eognathodus sulcatus kindlei Lane and Ormiston, Eognathodus sulcatus n. ssp. A, Eognathodus sulcatus n. ssp. B, Ozarkodina eberleini Savage, Kimognathus alexeii Mashkova, Kimognathus n. sp. A, and Kimognathus n. sp. B. The occurrences indicate that Lower Devonian deposits are widespread on Prince of Wales Island. On Wadleigh Island, Zlichovian, and probably older, deposits underlie Eifelian beds of the Wadleigh Limestone, previously thought to include limestone only of Middle and Late Devonian age. The Early Devonian faunas of this part of southeastern Alaska contain species characteristic of Cordilleran North America. There are strong affinities with Nevada, eastern Australia, and central Asia, but lesser affinities with central and eastern Europe. Affinities with eastern North America and western Europe are relatively weak. Regional variations in conodont color alteration indices suggest that the southern half of Prince of Wales Island has a different post-Devonian thermal history from the northern half.
Classification and conodont-based age of the Ordovician trilobite Ellsaspis (middle Arenigian, Ville Guay, Quebec)
Authors: Landing Ed , Ludvigsen Rolf
Published: November 2010

Ellsaspis Rasetti, 1945 occurs in a thin intraclast granule and echinoderm hash packstone in continental slope facies at Ville Guay. Presence of an anterior median glabellar node and assignment of a previously unrecognized pygdium to the type species support its classification as an endymioniine trilobite. Associated conodonts of the platform margin Juanognathus biofacies, a chitinozoan, and shelf-derived orthids indicate a correlation with the middle Arenigian and upper Canadian. Association of the conodonts Prioniodus evae and P. elegans precludes a precise correlation with the condensed sequences of the Baltic Basin.
Gene insulation. Part I: natural strategies in yeast and Drosophila
Authors: Amouyal Michèle
Published: November 2010

This review in two parts deals with the increasing number of processes known to be used by eukaryotic cells to protect gene expression from undesired genomic enhancer or chromatin effects, by means of the so-called insulators or barriers. The most advanced studies in this expanding field concern yeasts and Drosophila (this article) and the vertebrates (next article in this issue). Clearly, the cell makes use of every gene context to find the appropriate, economic, solution. Thus, besides the elements formerly identified and specifically dedicated to insulation, a number of unexpected elements are diverted from their usual function to structure the genome and enhancer action or to prevent heterochromatin spreading. They are, for instance, genes actively transcribed by RNA polymerase II or III, partial elements of these transcriptional machineries (stalled RNA polymerase II, normally required by genes that must respond quickly to stimuli, or TFIIIC bound at its B-box, normally required by RNA polymerase III for assembly of the transcription initiation complex at tRNA genes), or genomic sequences occupied by variants of standard histones, which, being rapidly and permanently replaced, impede heterochromatin formation.
Gene insulation. Part II: natural strategies in vertebrates
Authors: Amouyal Michèle
Published: November 2010

The way a gene is insulated from its genomic environment in vertebrates is not basically different from what is observed in yeast and Drosophila (preceding article in this issue). If the formation of a looped chromatin domain, whether generated by attachment to the nuclear matrix or not, has become a classic way to confine an enhancer to a specific genomic domain and to coordinate, sequentially or simultaneously, gene expression in a given program, its role has been extended to new networks of genes or regulators within the same gene. A wider definition of the bases of the chromatin loops (nonchromosomal nuclear structures or genomic interacting elements) is also available. However, whereas insulation in Drosophila is due to a variety of proteins, in vertebrates insulators are still practically limited to CTCF (the CCCTC-binding factor), which appears in all cases to be the linchpin of an architecture that structures the assembly of DNA–protein interactions for gene regulation. As in yeast and Drosophila, the economy of means is the rule and the same unexpected diversion of known transcription elements (active or poised RNA polymerases, TFIIIC elements out of tRNA genes, permanent histone replacement) is observed, with variants peculiar to CTCF. Thus, besides structuring DNA looping, CTCF is a barrier to DNA methylation or interferes with all sorts of transcription processes, such as that generating heterochromatin.
DISGUISED DISCRIMINATION OF LOCALITY-BASED UNSUPERVISED DIMENSIONALITY REDUCTION
Authors: YANG BO , CHEN SONGCAN
Published: November 2010

Many locality-based unsupervised dimensionality reduction (DR) algorithms have recently been proposed and demonstrated to be effective to a certain degree in some classification tasks. In this paper, we aim to show that: (1) a discriminant disposal is intentionally or unintentionally induced from the construction of locality in these unsupervised algorithms, however, such a discrimination is often inconsistent with the actual class information, so here called disguised discrimination; (2) sensitivities of these algorithms to local neighbor parameters stem from the inconsistency between the disguised discrimination and the actual class information; (3) how such inconsistency impacts the classification performance of these algorithms. The experiments on the benchmark face datasets testify our statements that are expected to provide some insight into the unsupervised leaning based on locality.
UANN BASED PATTERN CLASSIFIER USING ROUGH SET APPROACH
Authors: KOTHARI ASHWIN , KESKAR AVINASH
Published: November 2010

Data mining currently is a vital and core process because of advances in the technology, and numerous other forms of data. As an essential and significant constituent of data mining, classification has also become vital and a sought-after-option for research. Over the years, as various soft computing tools have been proven to be more complimentary than competitive, many hybrid approaches have evolved for pattern classification. A major thrust has always been there to apply hybrid approaches involving artificial neural network as the main tool for pattern classification. Here, one such hybrid approach is presented with application of Rough set philosophy to unsupervised artificial neural network (UANN) based pattern classifier. This enhances the performance of the classifier and makes it more suitable for real time classification applications dealing with large and unlabeled data. The idea presented here discusses with possibility and application of various Rough set based approaches at different levels of implementation of such classifier. The concluding section presents the results achieved for data of two case studies related to face recognition and mobile handoff prediction.
DISTURBING SMOOTH TRANSITIVE INTERVAL MAPS
Authors: BALIBREA FRANCISCO , GUIRAO JUAN L. G. , LÓPEZ MIGUEL A.
Published: November 2010

We show for the class [Formula: see text] of all C∞, transitive and topologically conjugate to algebraic polynomials interval self-maps the following stability type property: the class [Formula: see text] has no isolated points and for every [Formula: see text] and any ε arbitrary small positive real number there exists a map [Formula: see text] sharing with f the same fixed points except one and such that ‖ f - g ‖1 = ε. On the contrary, we also show for each [Formula: see text] that the re exists a C∞ interval self-map topologically conjugate to a polynomial, not transitive and ‖ ⋅ ‖1-arbitrary close to the map f.
ANALYSIS OF A FINITE VOLUME METHOD FOR A CROSS-DIFFUSION MODEL IN POPULATION DYNAMICS
Authors: ANDREIANOV BORIS , BENDAHMANE MOSTAFA , RUIZ-BAIER RICARDO
Published: November 2010

The main goal of this paper is to propose a convergent finite volume method for a reaction–diffusion system with cross-diffusion. First, we sketch an existence proof for a class of cross-diffusion systems. Then the standard two-point finite volume fluxes are used in combination with a nonlinear positivity-preserving approximation of the cross-diffusion coefficients. Existence and uniqueness of the approximate solution are addressed, and it is also shown that the scheme converges to the corresponding weak solution for the studied model. Furthermore, we provide a stability analysis to study pattern-formation phenomena, and we perform two-dimensional numerical examples which exhibit formation of nonuniform spatial patterns. From the simulations it is also found that experimental rates of convergence are slightly below second order. The convergence proof uses two ingredients of interest for various applications, namely the discrete Sobolev embedding inequalities with general boundary conditions and a spacetime L1 compactness argument that mimics the compactness lemma due to Kruzhkov. The proofs of these results are given in the Appendix.
Eroding Australia: rates and processes from Bega Valley to Arnhem Land
Authors: Heimsath Arjun M. , Chappell John , Fifield Keith
Published: November 2010

We report erosion rates determined from
in situ
produced cosmogenic
10
Be across a spectrum of Australian climatic zones, from the soil-mantled SE Australian escarpment through semi-arid bedrock ranges of southern and central Australia, to soil-mantled ridges at a monsoonal tropical site near the Arnhem escarpment. Climate has a major effect on the balance between erosion and transport and also on erosion rate: the highest rates, averaging 35 m Ma
−1
, were from soil-mantled, transport-limited spurs in the humid temperate region around the base of the SE escarpment; the lowest, averaging about 1.5 m Ma
−1
, were from the steep, weathering-limited, rocky slopes of Kings Canyon and Mt Sonder in semi-arid central Australia. Between these extremes, other factors come into play including rock-type, slope, and recruitment of vegetation. We measured intermediate average erosion rates from rocky slopes in the semi-arid Flinders and MacDonnell ranges, and from soil-mantled sites at both semi-arid Tyler Pass in central Australia and the tropical monsoonal site. At soil-mantled sites in both the SE and tropical north, soil production generally declines exponentially with increasing soil thickness, although at the tropical site this relationship does not persist under thin soil thicknesses and the relationship here is ‘humped’. Results from Tyler Pass show uniform soil thicknesses and soil production rates of about 6.5 m Ma
−1
, supporting a longstanding hypothesis that equilibrium, soil-mantled hillslopes erode in concert with stream incision and form convex-up spurs of constant curvature. Moreover, weathering-limited slopes and spurs also occur in the same region: the average erosion rate for rocky sandstone spurs at Glen Helen is 7 m Ma
−1
, similar to the Tyler Pass soil-mantled slopes, whereas the average rate for high, quartzite spurs at Mount Sonder is 1.8 m Ma
−1
. The extremely low rates measured across bedrock-dominated landscapes suggest that the ridge–valley topography observed today is likely to have been shaped as long ago as the Late Miocene. These rates and processes quantified across different, undisturbed landscapes provide critical data for landscape evolution models.
MPI as a Programming Model for High-Performance Reconfigurable Computers
Authors: Saldaña Manuel , Patel Arun , Madill Christopher , Nunes Daniel , Wang Danyao , Chow Paul , Wittig Ralph , Styles Henry , Putnam Andrew
Published: November 2010

High-Performance Reconfigurable Computers (HPRCs) consist of one or more standard microprocessors tightly-coupled with one or more reconfigurable FPGAs. HPRCs have been shown to provide good speedups and good cost/performance ratios, but not necessarily ease of use, leading to a slow acceptance of this technology. HPRCs introduce new design challenges, such as the lack of portability across platforms, incompatibilities with legacy code, users reluctant to change their code base, a prolonged learning curve, and the need for a system-level Hardware/Software co-design development flow. This article presents the evolution and current work on TMD-MPI, which started as an MPI-based programming model for Multiprocessor Systems-on-Chip implemented in FPGAs, and has now evolved to include multiple X86 processors. TMD-MPI is shown to address current design challenges in HPRC usage, suggesting that the MPI standard has enough syntax and semantics to program these new types of parallel architectures. Also presented is the
TMD-MPI Ecosystem
, which consists of research projects and tools that are developed around TMD-MPI to further improve HPRC usability. Finally, we present preliminary communication performance measurements.