bluuebunny/crossref_metadata_2025 huggingface dataset:
Nouvelles observations sur la morphologie des unités de croissance du hêtre (Fagus sylvatica L.). Symétrie des pousses, reflet de la vigueur des arbres
Authors: Nicolini Eric
Published: April 2011

Le hêtre a une croissance rythmique où chaque pousse annuelle est constituée d'une unité de croissance (u.c.) printanière parfois suivie, quelques semaines plus tard, d'une unité de croissance estivale. L'u.c. printanière présente une disposition foliaire alterne distique, tandis que l'u.c. estivale, selon certains auteurs, a une disposition foliaire alterne spiralée. Au terme d'observations morphologiques et histologiques de bourgeons formés à différentes périodes de l'année, il s'avère que la disposition foliaire du hêtre n'évolue pas d'un type d'u.c. à l'autre : les ébauches foliaires sont toujours disposées suivant deux droites parallèles, rapprochées sur un côté de la tige selon une disposition « plagiotrope distique ». La symétrie axiale d'une u.c. peut toutefois se modifier au cours de son allongement et évoluer d'une symétrie bilatérale vers une symétrie radiale secondaire. Cette évolution est le résultat d'une réorientation des nuds par torsion des entre-nuds, les plus grands déplacements d'organe foliaire étant réalisés par les u.c. les plus longues au niveau de leurs entre-nuds les plus longs. Il est possible de rattacher degré de développement des u.c. et architecture des arbres. Les arbres les moins vigoureux (très jeunes ou situés sous couvert forestier dense) ont un axe principal plus ou moins incliné, constitué d'u.c. peu développées dont la symétrie est bilatérale; l'axe principal est plagiotrope et porte un houppier plan. En revanche, les arbres les plus vigoureux (adultes ou en situations forestières favorables) ont un axe principal vertical, constitué d'u.c. relativement longues et de symétrie radiale; l'axe principal est orthotrope et porte un houppier bien réparti tout autour de lui.Mots clés : morphologie, Fagus, vigueur, disposition foliaire, architecture.
Mechanical stimulation, 4-aminobutyric acid (GABA) synthesis, and growth inhibition in soybean hypocotyl tissue
Authors: Bown Alan W , Zhang Guijin
Published: April 2011

4-Aminobutyric acid (GABA), a ubiquitous four-carbon nonprotein, amino acid, is synthesized via glutamate decarboxylation. It accumulates in response to mechanical stimulation through the Ca2+/calmodulin activation of glutamate decarboxylase. In this study, dark- and light-grown soybean hypocotyl tissues were used to investigate the relationship between mechanical stimulation, GABA synthesis, and growth inhibition. Mechanical stimulation through stroking resulted in a 65% growth inhibition of dark- or light-grown tissue within 1 min. The 24-h growth increment was reduced by 50% or more. Growth inhibition was accompanied by rapid 4- and 10-fold increases in GABA levels in dark- and light-grown tissue, respectively. Treatment of tissue with exogenous GABA raised GABA levels approximately 6-fold, but did not inhibit growth. In addition, lanthanum or blue light treatment of dark-grown tissue reduced growth by over 60% with no increase in GABA levels. The data demonstrate for the first time, that GABA accumulation accompanies growth inhibition occurring in response to mechanical stimulation. However, GABA accumulation alone appears insufficient to cause growth inhibition.Key words: 4-aminobutyric acid, GABA, L-Glu decarboxylase, GAD, thigmomorphogenesis, mechanical stimulation.
Partial purification and properties of apoplastic β-1,3 glucanases of groundnut leaves treated with glucan isolated from a biocontrol agent,Acremonium obclavatum
Authors: Sathiyabama M , Balasubramanian R
Published: April 2011

Apoplastic β-1,3 glucanases (G1, G2) of Arachis hypogaea L. (peanut) leaves treated with glucan have been partially purified by ammonium sulphate precipitation, sephadex G-100, CM-Sephadex, DEAE-Sephadex chromatography, and preparative native PAGE electrophoretic techniques. The pI values of purified enzymes G1 and G2 were near 8 and 4, respectively. The apparent molecular masses of purified glucanases G1 and G2 from glucan-treated peanut leaves were 36 and 34 kDa, respectively. Both isoforms (G1 and G2) showed their pH optimum of 5.0 and temperature optimum of 40°C. The partially purified enzymes hydrolysed laminarin better than other substrates and inhibited uredospore germination of Puccinia arachidis. Both isoforms (G1 and G2) inhibited spore germination of some biocontrol agents such as Acremonium obclavatum W. Gams, Myrothecium verrucaria (Alb. Schw.) Ditmer, Fusarium solani (Mart.) Sacc., and Trichoderma harzianum Rifai.Key words: Acremonium obclavatum, Arachis hypogaea, β-1,3 glucanase, glucan, inhibition, Puccinia arachidis.
The seed bank in an old-growth, temperate deciduous forest
Authors: Leckie Sara , Vellend Mark , Bell Graham , Waterway Marcia J , Lechowicz Martin J
Published: April 2011

We assessed the size and composition of the seed bank in 31 plots representing a range of habitats within an old-growth, temperate deciduous forest at Mont St. Hilaire, Québec, Canada. We identified 49 taxa in the seed bank, with an average of 40 species·m-2 and a median density of 1218 seeds·m-2. The most frequent seeds were species of Carex and Rubus, Diervilla lonicera, and Eupatorium rugosum, while seeds of Carex were the most numerous overall. Of the 12 species in the seed bank not found in the forest, 11 were found growing on the developed landscape surrounding this 10-km2 forest fragment. These nonforest species were numerically only a minor component of the forest seed bank. Vernal herbs were not in the seed bank, and there were only a few tree species. Variation in seed bank richness among habitats was correlated positively with canopy cover, soil moisture, and soil nutrients, but not with the seed bank density or total number of species in the aboveground vegetation. Seed bank density increased with plot soil moisture. Woody species predominated in the seed bank of plots with richer soils, deeper litter, and more closed canopies. Herbaceous species predominated in the seed bank of plots with more open canopies, more mesic water regimes, and greater species richness in the aboveground vegetation. Contrary to earlier results suggesting forest seed banks primarily include shade-intolerant species associated with canopy disturbance or secondary succession, the seed bank in this old-growth, primary forest contains many shade-tolerant forest species.Key words: seed bank, old-growth forest, primary forest, temperate deciduous forest, habitat diversity, seed dispersal.
Petrology of the Abloviak Aillikite dykes, New Québec: evidence for a Cambrian diamondiferous alkaline province in northeastern North America
Authors: Digonnet Stéphane , Goulet Normand , Bourne James , Stevenson Ross , Archibald Doug
Published: April 2011

A dozen ultramafic lamprophyre dykes have been identified in the eastern part of Ungava Bay, Québec. The dark grey dykes are composed of macrocrysts of olivine and phlogopite featuring tetraferriphlogopite rims. These minerals are included in a matrix consisting of fine-grained phlogopite, olivine, spinel, and interstitial carbonate. The geochemical composition, mineral assemblage, chemical analyses of the xenocrysts and phenocrysts and Sm-Nd isotopic signature indicate that these rocks are carbonated ultramafic lamprophyre dykes. The chemical zonation of the micas and the presence of andradite suggest a complex sequence of crystallization. An Ar isotope correlation analysis indicates an age of approximately 550 Ma. The dykes have intruded the Tasiuyak gneiss, a suite of Paleoproterozoic metasedimentary rocks. This unit occupies the Torngat Orogen collision zone between the Rae Province and the Nain Province. The dykes are considered to have been emplaced within tension gashes during reactivation of major Paleoproterozoic structures and fractures associated with the opening of the Iapetus Ocean. They are possibly related to a mantle plume that simultaneously caused both the rupture of the Laurentia and the formation of the ultramafic magma. The Abloviak lamprophyres have quite similar analogues in southwest Greenland. The age, geochemical characteristics, isotopic signature common to all these dykes, the geological environment of the southwest Greenland are all comparable with the data presented here for the Abloviak lamprophyres. Furthermore their pre-drift geographical proximity, prior to the opening of the Labrador Sea, suggests that they are related to a common magmatic event which constitutes a diamondiferous alkaline province located in northeastern North America.
Early Devonian eurypterids from the Northwest Territories of Arctic Canada
Authors: Braddy Simon J , Dunlop Jason A
Published: April 2011

A new eurypterid fauna from the Lower Bear Rock Formation (Early Devonian, Emsian) of Anderson River, in the Northwest Territories of the Canadian Arctic, is described. The material comprises an almost complete specimen and five isolated carapaces of Erieopterus microphthalmus; an incomplete carapace and telson referred to Drepanopterus sp.; and an isolated prosomal appendage of Carcinosoma sp. Associations include actinopterygian, sarcopterygian, and acanthodian fish, as well as lingulids, conchostracans, ostracodes, coprolites, and plant material. A nearshore marine environment is inferred. This assemblage provides the first Canadian record of Drepanopterus and the youngest Canadian occurrences of erieopterid and carcinosomatid eurypterids.
Hinge modifications and musculature of strophomenoid brachiopods: examples across the Ordovician-Silurian boundary, Anticosti Island, Quebec
Authors: Dewing Keith
Published: April 2011

Six modifications to the hinge occur in strophomenoid brachiopods from Anticosti Island: (1) overhanging socket ridges; (2) posterolateral socket ridges along the interarea articulate with grooves on the posterior of teeth; (3) anteromedian dental notches articulate with the crests of socket ridges; (4) dental crenulations on the surfaces of teeth mesh with socket ridges; (5) denticles extend laterally to the cardinal extremities; and (6) the margin of the ventral interarea fits into a long socket along the dorsal interarea forming a lateral tooth. Denticulate hinges and dental notches that typify Silurian and Devonian strophomenids begin in the fauna of the Ellis Bay Formation. Thus the most important interval of strophomenid faunal turnover was at the base of the Gamachian (the base of the Hirnantian) and not at the OrdovicianSilurian boundary. Muscle attachment pads in the delthyrial cavity do not correspond to the positions of either the adductor or diductor muscle scars. Pedicle adjustor muscles in modern brachiopods occupy this position. The round gap between the median fold of the pseudodeltidium and groove on chilidium is proposed as the point of emergence of the pedicle muscle. The tiny foramen, commonly sealed early in growth, is suggested to be part of a neanic water-intake system, active before the growth of the cardinal process in ephebic shells. Once the cardinal process appeared, the foramen was blocked. Recurring types of strophomenid ornamentation, such as posteriorly steepened rugae and checkerboard ornamentation, may have served as a plow to redistribute sediment as the shell was pulled backwards along the pedicle.
Dimorphism and a new record ofBarroisicerasDe Grossouvre (Ammonoidea) from the Coniacian of Bagh, central India
Authors: Gangopadhyay T K , Bardhan S
Published: April 2011

Barroisiceras de Grossouvre was hitherto unknown in India. B. onilahyense Basse, which elsewhere belongs exclusively to the Coniacian, has been recorded from the Bryozoan Limestone Formation of central India. This find, as well as the presence of another time-diagnostic Coniacian ammonite, Placenticeras kaffrarium Etheridge and two inoceramid bivalves, Inoceramus (Mytiloides) incertus Jimbo and I. (Platyceramus) mantelli (Barrois) Mercey in the underlying horizons, help in resolving the long standing problem of the age of the Bagh Group. B. onilahyense shows wide intraspecific variability and overlaps morphometrically with the late Turonian type species, B. haberfellneri (Hauer). They may be conspecific. The present species has been found to be sexually dimorphic, a phenomenon previously not well recognised in the subfamily Barroisiceratinae. As in many Late Cretaceous ammonites, dimorphism is manifest mainly by differences in relative adult sizes and in strength of ornamentation, the microconch being smaller and more strongly ornamented.
Tectonic deformation and magmatism along the southern flank of the Maritimes Basin: the northeastern Cobequid Highlands, Nova Scotia
Authors: Piper David JW , Pe-Piper Georgia
Published: April 2011

Distributed crustal-scale faulting in the Cobequid Highlands in the Middle Devonian to Carboniferous resulted from the oblique convergence of the Meguma and Avalon terranes. In the northeastern Cobequid Highlands, seismic reflection profiles show Neoproterozoic and lower Paleozoic rocks, together with enigmatic foliated rocks, overlying the Early Carboniferous Fountain Lake Group. The foliated rocks form the hanging wall of a north-vergent thrust fault. Their protolith is inferred from petrography and geochemistry to be principally Neoproterozoic rhyodacitic tuff and late Paleozoic hypabyssal intrusions. The age of thrusting is stratigraphically constrained to the late Tournaisian  mid-Viséan, and sericite from mylonite yielded a Tournaisian KAr age of 352 ± 8 Ma. The thrusting occurs at the base of a tectonic escape sheet and resulted from a restraining bend in the Rockland Brook master fault. Farther west, where the Rockland Brook fault trends almost eastwest, Tournaisian extensional features include the Nuttby basin and widespread gabbro dykes, sills, and stocks. At deeper structural levels, granite plutons were intruded in a similar tectonic regime of thrusting and local extension by lateral movement of basement blocks. The emplacement process resulted from progressive widening of initial dykes, analogous to the dykes deformed in the thrust hanging wall. Regionally, in the Tournaisian of the southern Maritimes Basin half-graben formation was synchronous with pluton emplacement and thrusting in adjacent horsts.
U-Pb ages of granitoid rocks in the northwestern Makkovik Province, Labrador: evidence for 175 million years of episodic synorogenic and postorogenic plutonism
Authors: Ketchum John WF , Barr Sandra M , Culshaw Nicholas G , White Chris E
Published: April 2011

New UPb zircon, titanite, and monazite ages reported here, along with existing age data, demonstrate that granitoid bodies in the northwestern segment of the Paleoproterozoic Makkovik Province, Labrador, are of three distinct ages. The redefined Island Harbour Bay plutonic suite consists of varied dioritic to granitic units that were syntectonically emplaced into Archean crust of the Kaipokok domain between ca. 1895 Ma and 1870 ± 2 Ma. This plutonism occurred during the early stages of the Makkovikian Orogeny in an obliquely convergent, Andean continental margin setting. The Hares Islands and Drunken Harbour granites form smaller, discrete plutons that were emplaced in or adjacent to the Island Harbour Bay plutonic suite at 1805 ± 5 Ma and 1791 ± 2 Ma, respectively, during dextral strike-slip deformation that accompanied accretion of an outboard juvenile terrane. Magmatic activity during this period was preferentially sited along active structural zones, but also occurred outside of these zones. The undeformed Blacklers Bight A-type granite was emplaced in the Kaipokok domain at 1716 ± 1 Ma, late in the development of the orogen. A-type granites of this age form a significant component of the southeastern Makkovik Province, and their generation is linked to mafic underplating and heterogeneous regional extension. The new age data support the conclusion of earlier workers that crustal growth via synorogenic and postorogenic plutonism was episodic, and allow, along with field and geochemical data, inferences to be made regarding the tectonic setting of individual plutonic events.
Controls on the distribution of thermal springs in the southern Canadian Cordillera
Authors: Grasby Stephen E , Hutcheon Ian
Published: April 2011

Thermal springs examined in southern British Columbia are restricted to six major Eocene or later brittle fault systems. These faults provide a high-permeability flow path that allows for deep circulation of meteoric water. The depth of circulation, and thus temperature, is largely influenced by fault plane geometry. Calculated circulation depths of up to 4.8 km are consistent with models for hydrothermal ore deposits that invoke the mixing of mineralizing fluids with sulphur-rich meteoric water at depth. Mass-flux calculations indicate that a relatively small spring (5 L/s) can transport large amounts of bacterially reduced sulphur to ore-forming depths over a short geological time scale and can easily account for the sulphur associated with PbZn deposits in the southern Canadian Cordillera. Modern thermal springs may be good analogies for the upper-crustal flow systems in hydrothermal ore deposit models.
The influence of mantle plume in the genesis of the Cache Creek oceanic igneous rocks: implications for the geodynamic evolution of the inner accreted terranes of the Canadian Cordillera
Authors: Tardy M , Lapierre H , Struik L C , Bosch D , Brunet P
Published: April 2011

West of Prince George, British Columbia, the Cache Creek Terrane is composed of mafic lavas interlayered with both mid-Permian pelagic limestones and Upper Triassic siliceous shales and greywackes. Gabbro, basalt, dolerites, and foliated clinopyroxene-rich ultramafic rocks are exposed within the Pinchi Fault system. The mid-Permian lavas show affinities of oceanic island tholeiites. Among the Triassic lavas, three types of rocks have been distinguished. Type 1 is geochemically similar to the mid-Permian volcanic rocks. Type 2 differs from type 1 by higher TiO2 abundances and convex rare earth element patterns. Type 3 has the highest Zr, Nb, and Ta abundances and the greatest light rare earth element enrichment. The mafic rocks within the Pinchi Fault system are similar to N-type mid-ocean-ridge basalt (N-MORB), and the foliated ultramafic rocks are characterized by very low trace element contents, similar to extremely depleted harzburgites. Permian lavas and Triassic type 1 and igneous rocks from the Pinchi Fault system have the highest εNd(i) ratios (+7.4 to +9.6) and those of type 3 alkali have the lowest ratios (+2.0 to +5.3). The εNd(i) values of type 2 are intermediate between those of type 1 (~+7) and type 3 (~+4.9). This suggests that the Triassic rocks generated from a heterogeneous plume source or the mixing between depleted N-MORB and enriched oceanic island basalt sources. If the mafic igneous rocks sampled in central British Columbia are representative of the preserved parts of an oceanic crust, within the Cache Creek Terrane, then that crust was dominated by oceanic plateau components, perhaps due to the difficulty of subducting thick crust.
A new species of Dimetrodon (Synapsida: Sphenacodontidae) from the Lower Permian of Germany records first occurrence of genus outside of North America
Authors: Berman David S , Reisz Robert R , Martens Thomas , Henrici Amy C
Published: April 2011

A new species of the sphenacodontid synapsid Dimetrodon, D. teutonis, is described on the basis of a single, adult specimen consisting of a large portion of the presacral vertebral column. The holotype was collected from the Lower Permian Tambach Formation, lowermost formational unit of the Upper Rotliegend, of the Bromacker quarry locality in the midregion of the Thuringian Forest near Gotha, central Germany. This is the first record of the genus outside of North America and, therefore, provides not only additional biological evidence of a continuous Euramerican landmass during the Early Permian, but also the absence of any major physical or biological barrier to faunal interchange of terrestrial vertebrates. An estimated weight of 14 kg for D. teutonis is half that of the smallest, previously recognized species, D. natalis. Sphenacodontid phylogeny indicates that the diminutive size of D. teutonis represents an autapomorphy and is in general accord with the absence of large-sized, basal synapsid predators at this truly terrestrial upland locality. It is speculated that the diminutive size of D. teutonis was probably an adaptation to a truly terrestrial, relatively uplands existence like that represented by the Bromacker locality. Here it subsisted on small vertebrates (and possibly large invertebrates) of the Bromacker assemblage, in which the dominant members in both size and abundance were herbivorous diadectids, and it was unlikely to encounter large predators.
Biostratigraphic and biogeographic constraints on the Carboniferous to Jurassic Cache Creek Terrane in central British Columbia
Authors: Orchard M J , Cordey F , Rui L , Bamber E W , Mamet B , Struik L C , Sano H , Taylor H J
Published: April 2011

Conodonts, radiolarians, foraminiferids, and corals provide constraints on the geology and tectonics of the Nechako region. They also support the notion that the Cache Creek Terrane is allochthonous with respect to the North American craton. The 177 conodont collections, assigned to 20 faunas, range in age from Bashkirian (Late Carboniferous) to Norian (Late Triassic); 70 radiolarian collections representing 12 zones range from Gzhelian (Late Carboniferous) to Toarcian (Early Jurassic); 335 collections assigned to 11 fusulinacean assemblages (with associated foram-algal associations) range from Bashkirian to Wordian (Middle Permian); and two coral faunas are of Bashkirian and Wordian age. The fossils document a long but sporadic history of sedimentary events within the Cache Creek Complex that included two major carbonate buildups in the Late Carboniferous (Pope limestone) and Middle Permian (Copley limestone), punctuated by intervening Early Permian deepening; basaltic eruptions during the mid Carboniferous and mid Permian; the onset of oceanic chert sedimentation close to the CarboniferousPermian boundary and its persistence through the Late Triassic (Sowchea succession); latest Permian and Early Triassic mixed clastics and volcanics (Kloch Lake succession); Middle and Late Triassic reworking of carbonates (Whitefish limestone), including cavity fill in older limestones (Necoslie breccia), and fine-grained clastic sedimentation extending into the Early Jurassic (Tezzeron succession). Tethyan, eastern Pacific, and (or) low-latitude biogeographic attributes of the faunas are noted in the Gzhelian (fusulines), Artinskian (conodonts, fusulines), Wordian (fusulines, corals, conodonts), and Ladinian (conodonts, radiolarians). The Cache Creek Terrane lay far to the west of the North American continent during these times.
Geochemistry and oxygen isotopic composition of the Canton Saint-Onge wollastonite deposit, central Grenville Province, Canada
Authors: Higgins Michael D , Beisswenger Arlene , Hoy Lawrence D
Published: April 2011

The geology and geochemistry of the Canton Saint-Onge wollastonite deposit indicate that it is a skarn formed by silica metasomatism of dolomite-rich rocks. Oxygen isotopic compositions of the skarn rocks and the nearby plutons show that the fluids responsible for the metasomatism were not meteoric, but were probably associated with the Du Bras granitic pluton. However, the granite is not in contact with the wollastonite rocks at the present level of exposure, hence the fluids must have been released at greater depths. Wollastonite-rich parts of the skarn rocks are isotopically lighter than diopside-rich rocks, suggesting that wollastonite formed in regions of higher fluid flux.
The skull and tooth system of Orlovichthys limnatis, a Late Devonian dipnoan from Russia
Authors: Krupina N I , Reisz R R , Scott D
Published: April 2011

The cranial anatomy of Orlovichthys limnatis, a Famennian, Late Devonian dipnoan from the Orel region of central Russia, is described on the basis of an almost completely preserved skull, a mandible, and numerous elements of the dentition. Orlovichthys is distinguished from other tooth-plated Devonian dipnoans by its relatively narrow skull and its predatory type of tooth-plate morphology on the pterygoid and prearticular. The marginal dentition of Orlovichthys, which extends transversely across the edge of the ossified ethmoid (upper lip) and along the anterior and lateral edges of the dentary, also appears to be organized as tooth plates. The distribution of marginal dentition among Devonian dipnoans and their probable organization as tooth plates prompts us to suggest that an important developmental constraint may have been associated with the dipnoan dentition throughout the long history of this group.
Paleomagnetism of the Upper Cretaceous Nanaimo Group, southwestern Canadian Cordillera
Authors: Enkin Randolph J , Baker Judith , Mustard Peter S
Published: April 2011

The Baja B.C. model has the Insular Superterrane and related entities of the Canadian Cordillera subject to >3000 km of northward displacement with respect to cratonic North America from ~90 to ~50 Ma. The Upper Cretaceous Nanaimo Group (on and about Vancouver Island, British Columbia) is a prime target to test the model paleomagnetically because of its locality and age. We have widely sampled the basin (67 sites from seven islands spread over 150 km, Santonian to Maastrichtian age). Most samples have low unblocking temperatures (<450°C) and coercivities (~10 mT) and strong present-field contamination, forcing us to reject three quarters of the collection. Beds are insufficiently tilted to provide a conclusive fold test, and we see evidence of relative vertical axis rotations. However, inclination-only analysis indicates pretilting remanence is preserved for many samples. Both polarities are observed, and reversals correlate well to paleontological data, proving that primary remanence is observed. The mean inclination, 55 ± 3°, is 13 ± 4° steeper than previously published results. Our new paleolatitude, 35.7 ± 2.6° is identical to that determined from the slightly older Silverquick and Powell Creek formations at Mount Tatlow, yet the inferred displacement is smaller (2300 ± 400 km versus 3000 ± 500 km) because North America was drifting southward starting around 90 Ma. The interpreted paleolatitude conflicts with sedimentologic and paleontologic evidence that the Nanaimo Basin was deposited near its present northern position.
Holocene paleoclimate and paleoecology determined from fossil Coleoptera at Brampton, Ontario, Canada
Authors: Motz John E , Morgan Alan V
Published: April 2011

An unusually rich and extensive 5 m sequence of organic-rich sediments (ca. 13 000 to ca. 4500 BP) from a drained glacial kettle near Brampton, Ontario, has produced a large and varied assemblage of fossil insects. Coleoptera (beetles) from the base include species typical of northern boreal or tree line habitats today. Approximately one metre above the base of the section (ca. 11 500 BP), there is an abrupt appearance of numerous bark beetles (family Scolytidae) and other Coleoptera that inhabit boreal forests. Temperate species whose ranges are predominantly or totally south of the Ontario border, appear, beginning at ca. 9500 BP, suggesting environmental conditions similar to modern ones. Younger Dryas and Pre-Boreal Oscillation cold events may be evident in lower parts of the boreal sequence, although considerations of temporal and climatic resolution make interpretation somewhat ambiguous.
Geology of the Chatham Sound region, southeast Alaska and coastal British Columbia
Authors: Gehrels George E
Published: April 2011

The Coast Mountains orogen is thought to have formed as a result of accretion of the Alexander and Wrangellia terranes against the western margin of the Stikine and YukonTanana terranes, but the nature and age of accretion remain controversial. The Chatham Sound area, which is located along the west flank of the Coast Mountains near the Alaska  British Columbia border, displays a wide variety of relations that bear on the nature and age of the boundary between inboard and outboard terranes. Geologic and UPb geochronologic studies in this area reveal a coherent but deformed and metamorphosed sequence of rocks belonging to the YukonTanana terrane, including pre-mid-Paleozoic marble, schist, and quartzite, mid-Paleozoic orthogneiss and metavolcanic rocks, and upper Paleozoic metaconglomerate and metavolcanic rocks. These rocks are overlain by Middle Jurassic volcanic rocks (Moffat volcanics) and Upper Jurassic  Lower Cretaceous strata of the Gravina basin, both of which also overlie Triassic and older rocks of the Alexander terrane. This overlap relationship demonstrates that the Alexander and Wrangellia terranes were initially accreted to the margin of inboard terranes during or prior to mid-Jurassic time. Accretion was apparently followed by Late Jurassic  Early Cretaceous extensiontranstension to form the Gravina basin, left-slip along the inboard margin of AlexanderWrangellia, mid-Cretaceous collapse of the Gravina basin and final structural accretion of the outboard terranes, and early Tertiary dip-slip motion on the Coast shear zone.
The Silurian(?) Passamaquoddy Bay mafic dyke swarm, New Brunswick: petrogenesis and tectonic implications
Authors: Van Wagoner Nancy A , Leybourne Matthew I , Dadd Kelsie A , Huskins Miranda LA
Published: April 2011

The volcanic and sedimentary rocks of the Passamaquoddy Bay (PB) area of southeastern New Brunswick are part of the SilurianDevonian Coastal Volcanic Belt (CVB), an extensive belt of bimodal volcanic rocks. The PB sequence is 4 km thick, has four cycles of mafic and felsic volcanism, and is intruded by mafic dykes at all levels. There are two ages of dykes, those related to the Late Silurian PB volcanism (PB dykes) and Mesozoic dykes (the Minister Island Dyke) related to the opening of the North Atlantic. The PB mafic dykes are subalkalic basalt to basaltic andesite, within-plate tholeiites. The dykes are moderately to highly evolved (Mg# = 66.6 to 26.6), with trends of major and trace elements typical of the fractionation of olivine, pyroxene, plagioclase, and ilmenite. The PB mafic dyke swarm comprises over 155 dykes which represent a greater range of compositions than the associated flows, suggesting that they give a more complete representation of the Late Silurian PB mafic magmas. They exhibit incompatible element characteristics best accounted for by crustal contamination. The dykes plot on a linear array away from mantle mixing lines between depleted and enriched mantle sources and toward the composition of the PB felsic units, suggesting that these felsic units are representative of partial melts and fractionates of the source contaminate. The variable TiO2 contents (1.24.3 wt.%) and incompatible element ratio trends plotted against a fractionation index suggest that mantle metasomatism, either fluid or melt derived, may also have influenced the mantle source of the dykes. The dykes dip steeply and have a relatively consistent strike to the north. Most dykes range in thickness from 0.5 to 2 m, but range up to 9 m. The single orientation of the dykes, along with their chemical characteristics and volume, and association with a bimodal intraplate volcanic sequence, are consistent with an extensional tectonic setting. Constraints of the regional geology suggest that this extension was associated with convergence, perhaps in a back-arc setting.
A review of Leidyosuchus canadensis Lambe, 1907 (Archosauria: Crocodylia) and an assessment of cranial variation based upon new material
Authors: Wu Xiao-Chun , Russell Anthony P , Brinkman Donald B
Published: April 2011

Cranial morphology of Leidyosuchus canadensis Lambe 1907 is reviewed based on previously undescribed materialseven skulls and eight mandibles. This species can be distinctively diagnosed by more than 10 derived features. New information supports the contention that L. canadensis is the sole representative of Leidyosuchus, and indicates that it is very different from the other species previously assigned to this taxon. The membership of L. canadensis within Alligatoroidea is also demonstrated by new information revealed in this study. Ontogenetic and individual variation in the cranial anatomy of L. canadensis are documented. The contact of the premaxillarymaxillary suture with the incisive foramen is not diagnostic of the taxon; rather, it exhibits individual variation. Leidyosuchus is endemic to North America. There was no faunal interchange of crocodyliforms between North America and central Asia during the last two stages of the Late Cretaceous.
ABSOLUTE AGE OF THE FISSET BROOK FORMATION AND THE DEVONIAN-MISSISSIPPIAN BOUNDARY, CAPE BRETON ISLAND, NOVA SCOTIA
Authors: Cormier R. F. , Kelly A. M.
Published: April 2011

The Fisset Brook formation of sedimentary and volcanic rocks crops out in the Cheticamp area of Cape Breton Island, Nova Scotia. Its stratigraphic age has been determined as earliest Mississippian using spores contained in the sedimentary members. A rubidium–strontium age determination using whole-rock samples of the volcanic members has yielded an age of 349 ± 15 million years. This is in good agreement with age determinations elsewhere for the Devonian–Mississippian boundary. Similar rocks exposed to the east of Lake Ainslie, some thirty miles to the southwest, give an identical age, 348 ± 20 million years. These rocks are clearly correlative with the Fisset Brook formation. Mixed sedimentary and volcanic rocks in the Cape St. Lawrence area, some thirty miles to the northeast of Fisset Brook, appear to be significantly older, 462 ± 25 million years, and should be considered tentatively as Ordovician in age.
REPEATED TRENDS OF FOLDS AND CROSS-FOLDS IN PALAEOZOIC ROCKS, PARRSBORO, NOVA SCOTIA
Authors: Fyson W. K.
Published: April 2011

On the north side of a major fault three generations of folds F1, F2, F3 affect pre-Carboniferous phyllites; south of the fault two generations, C1, C2, affect middle Carboniferous clastic rocks. The F1 folds are isoclinal and obscure. The main folds, F2 in the phyllites and C1 in the Carboniferous rocks, trend east-northeast parallel to the fault. F2 are overturned southward and C1 northward, both toward the fault. Cross-folds, F3 in the phyllites and C2 in the Carboniferous rocks, trend northnortheast. Steeply plunging F3 and C2 are asymmetric and Z-shaped in plan profile.The F2 folds in the phyllites, though similar in geometry to folds in the middle Carboniferous rocks, appear, like F1 and F2, to have formed prior to the middle Carboniferous. This is indicated by the occurrence of unfolded Devonian(?) granitic intrusions crossing F3 folds, and a few miles north of the major fault, by middle Carboniferous rocks lying unconformably- above similar intrusions.One possible explanation for the repeated trends, which also accounts for the sense of overturning and asymmetry of the folds, relates the folding to alternating vertical and horizontal movements along the major fault. The vertical movements were followed by gravity sliding toward the fault to produce the main folds, and the horizontal movements, repeatedly dextral in sense, resulted in the Z-shaped cross-folds.
EXPERIMENTAL INVESTIGATION OF CHALCOCITE: ANNEALING AND PLASTIC DEFORMATION AT ELEVATED TEMPERATURES
Authors: Davies Raymond
Published: April 2011

The recrystallization behavior and deformation of synthetic chalcocite (Cu2S) in the temperature range 400–725 °C was studied microscopically after the compound was annealed in evacuated silica glass capsules and heated under differential pressures in sealed gold capsules. The temperature of recrystallization and grain growth ascribed to the hexagonal cubic inversion, at sulfur vapor pressures much less than 1 atmosphere, was determined at 465 ± 5 °C, with annealing time of [Formula: see text].Experiments involving differential pressures of 8 000 p.s.i. show that chalcocite in the solid state becomes considerably more mobile above 563 ± 10 °C and can readily be injected as a plastic mass to form veins without preservation of deformational textures.Natural bornite and natural galena may also be injected under differential pressure at 640 °C, but some unhealed fractures remain. Flow structure is well-preserved in galena and, under certain conditions, in bornite.Mixtures of bornite and pyrite flowed and recrystallized to chalcopyrite and bornite with exsolved chalcopyrite. No evidence of flowage remained.Chalcopyrite and pyrrhotite are resistant to injection under similar differential pressures and temperatures.
REGIONAL HEAT FLOW PATTERN IN WESTERN CANADA
Authors: Anglin F. M. , Beck A. E.
Published: April 2011

Over a period of several years, thousands of temperature measurements, which were made while oil wells were being logged for other purposes, have accumulated. These measurements have now been critically examined. Although only a minute percentage were sufficiently reliable for terrestrial heat flow purposes, there were enough to permit sea level isogeotherms and isogradients to be drawn on a regional basis.Anomalies in the isogeotherms appear to correlate with granitic basement intrusions. The isogradients suggest a regional trend of increasing heat flow between Edmonton and Norman Wells.
LEAD ISOTOPE RATIOS FROM THE COBALT–NORANDA AREA, CANADA
Authors: Kanasewich E. R. , Farquhar R. M.
Published: April 2011

Lead isotope ratios indicate that very old galenas in Archean volcanics and sediments in the vicinity of Timmins, Ontario; Noranda and Val d'Or, Quebec, have had additions of younger lead of the type found near Cobalt, Ontario. The mixture of leads of two distinct ages has produced isotopic ratios which are linearly related. The greatest degree of mixing has occurred in areas such as Kirkland Lake which are close to the boundary between Archean rocks and the Bruce–Cobalt Series. Most of the lead appears to have been derived from a subsialic source region. From the relationship of the anomalous lead line and the single-stage growth curve commonly accepted for ordinary leads it is found that lead sulfide mineralization occurred 3 250 ± 150 million years (m.y.) ago in Archean rocks of Ontario and Quebec. The leads associated with mines along the northeastern edge of the Cobalt basin were separated from their uranium and thorium source region 2 300 ± 150 m.y. ago. Leads from Chibougamau, Quebec, appear to be related in age to the Cobalt leads. This study of 50 lead isotope ratios is a clear illustration of the claim that single-stage lead models must not be applied indiscriminately to isolated analyses of galena. It also produces evidence for the existence of crustal rocks in North America prior to 3 200 m.y. ago.
ON THE REGIONALITY OF ISOSTASY IN THE CANADIAN CORDILLERA
Authors: Elsaharty A. F. , Grant F. S.
Published: April 2011

A set of gravity observations was taken at 3- to 4-mile intervals along a traverse through the Canadian Cordillera close to the international border. The isostatic reduction and interpretation of these measurements indicate that compensation beneath the cordilleran massif is regional rather than local. Using the Vening-Meinesz tables, the values found for T (mean crustal thickness) and R (radius of regionally) were 30 km and 116 km, respectively. These values imply a mean crustal rigidity that is comparable in magnitude with values determined from seismology and from postglacial rebound.
THE PROPAGATION OF THE COMPRESSIONAL WAVE IN THE CRUST: II. SYNTHETIC SEISMOGRAMS
Authors: Keen M. J. , Tsong C. F.
Published: April 2011

Synthetic seismograms have been generated in an attempt to measure the attenuation of compressional waves beneath the Atlantic coast of Nova Scotia; the results suggest that the value of Q must be of the order of 300 whatever the mechanism of propagation may be. Comparison with results of experiments in the Gulf of St. Lawrence shows that attenuation of first events in the range of distance up to 60 km is more rapid in the rocks beneath the Gulf than in those beneath the Atlantic coast of Nova Scotia, This may be due either to attenuation in the upper sedimentary layers, present in the one place but not in the other, or to greater attenuation within rocks in which the compressional wave velocity is the same as in those beneath the Atlantic coast.
ELASTIC PROPERTIES OF SINGLE CRYSTALS OF ANHYDRITE
Authors: Schwerdtner W. M. , Tou J. C.-M. , Hertz P. B.
Published: April 2011

The nine moduli of compliance for anhydrite were obtained in uniaxial compression tests. The displacements were measured by strain gauges of an electrical resistance variety (Budd MetalFilm). Geophysical constants for the polycrystalline aggregates were also computed.
A REVIEW OF BORON SEDIMENTARY GEOCHEMISTRY IN RELATION TO NEW ANALYSES OF SOME NORTH AMERICAN SHALES
Authors: Shaw D. M. , Bugry R.
Published: April 2011

One hundred and sixty-eight North American shales, ranging in age from Proterozoic to Cretaceous, have been analyzed for boron; analyses for CO2 permitted corrections to a carbonate-free basis. The B values mostly agree with the inferred salinities of the environments of deposition, based on geological evidence: anomalously low values in the Devonian Littleton formation may be correlated with loss of B to regional quartz–tourmaline veins.The data do not permit drawing any inference regarding secular variations in oceanic B content.A review of recent work on B sedimentary geochemistry indicates the need for analyses of real, rather than hypothetical, mineral phases.
CRUSTAL STRUCTURE ON THE EASTERN SEABOARD OF CANADA: STUDIES ON THE CONTINENTAL MARGIN
Authors: Keen Charlotte , Loncarevic B. D.
Published: April 2011

The results of several seismic refraction profiles on the continental shelf and slope of the eastern seaboard of Canada are now available. Gravity measurements which begin near the coast of Nova Scotia and end over the abyssal plain have also been made along two tracks perpendicular to the shelf edge. Various models for the crustal and upper mantle structure are presented. A density distribution assumed for each model resulted in a computed gravity field satisfying the observed gravity measurements. The models in agreement with all seismic data suggest that horizontal and vertical density variations occur in the upper mantle down to 100 km. The results indicate a mantle density of 3.42 g/cm3 under the continental shelf and 3.32 g/cm3 under the ocean basin.
CARBONIFEROUS ROCKS OF THE CONCHE – GROAIS ISLAND AREA, NEWFOUNDLAND
Authors: Baird David M.
Published: April 2011

About 5 000 ft of Carboniferous sedimentary strata occur in the Cape Rouge and Conche peninsulas, small projections on the east side of the Great Northern Peninsula of Newfoundland. The lower 900 ft of the section consists of coarse conglomerate and sandstone, the fragments in which were derived from nearby older rocks. These lower beds are overlain by about 4 000 ft of shale and sandstone, in places petroliferous and with bituminous residues, and bearing plants and spores identified as of upper Horton (late Tournaisian) age. The sedimentary rocks described in this paper are the northernmost known Carboniferous rocks of the Appalachian belt. They lie in a basin between Groais Island and the Great Northern Peninsula and may possibly be continuous under the sea with the Grand Lake–White Bay basin a 100 mi to the southwest. The boundary fault on the west side of this Carboniferous basin is a portion of a fault system which is known to extend some 300 mi from the northern tip of Newfoundland to its southwest corner and is a portion of the Cabot fault of Wilson. Movement on the fault system appears to have been of at least three ages, pre-Horton (pre-Tournaisian), post-Horton–pre-Windsor (post-Tournaisian–pre-Visean), and post-early Pennsylvanian (post-Westphalian "A").
ANALOGUE MODEL MEASUREMENTS FOR ELECTROMAGNETIC VARIATIONS NEAR VERTICAL FAULTS AND DYKES
Authors: Dosso H. W.
Published: April 2011

An analogue model for studying the behavior of the natural geomagnetic and telluric field variations for various geological structures is described. Measurements of amplitudes and phases for the horizontal electric, the horizontal magnetic, and the vertical magnetic field components are obtained and discussed for various conducting vertical faults and dykes for both the H and the E polarizations.
EXPERIMENTS ON DENSITY AND TURBIDITY CURRENTS: I. MOTION OF THE HEAD
Authors: Middleton Gerard V.
Published: April 2011

Two series of experiments were performed in a lucite flume 5 meters long, 50 cm deep, and 15.4 cm wide. In the first series saline density currents were formed by pumping salt solutions at constant discharge into the tilted flume. In the second series, the flume was horizontal and turbidity currents were formed by the releasing of suspensions of plastic beads from a box at one end.In both series of experiments a characteristic head was formed at the front of the flow. It was found that the motion of the head in the turbidity current experiments was closely described by laws developed by Keulegan (1958) for saline surges, and it is concluded that certain aspects of the motion of turbidity current heads can be investigated indirectly by means of experiments on density currents formed from clay suspensions or salt solutions.The salt-solution experiments were designed to investigate the effect of bottom slope on the motion of density current heads. It was found that the velocity of density (and by inference, turbidity) current heads on slopes up to 4% is adequately expressed by Keulegan's formula[Formula: see text]where v is the velocity of the head, Δρ is the difference between the density of the current (ρ) and that of the overlying water, d2 is the thickness of the head, and g is the acceleration due to gravity. The numerical coefficient is approximately constant, but may increase slightly with increase in slope. The form of the equation differs greatly from that of the Chézy equation which has previously been used for the analysis of the movement of turbidity currents.Observations were also made regarding the shape of the head and the motion within and in front of the head.
JOINTING IN FOLDED CARDIUM SANDSTONES ALONG THE BOW RIVER, ALBERTA
Authors: Muecke G. K. , Charlesworth H. A. K.
Published: April 2011

Five thousand joints were examined in gently folded sandstones of the Cretaceous Cardium formation along the Bow River in the Rocky Mountain foothills of central Alberta. Twenty domains, based on homogeneity of bedding and joint orientation, were established. Joint sets from all domains fall into four classes, J1–4, all normal to bedding. J1 parallels the structural trend of the foothills, and occurs in all domains. J3 and J4 form conjugate pairs whose acute bisectrices are approximately normal to J1, and occur in western domains; the dihedral angle between conjugate pairs tends to decrease eastward. J2 is approximately normal to J1; poles to J2 sets have elongate maxima, and the sets replace conjugate J3−J4 sets in eastern domains. No joints are displaced by bedding-plane slip.J1 and J2 sets are interpreted as extension sets, and J3 and J4 sets as conjugate shear sets. Each J2 set represents conjugate shear sets with a dihedral angle too small to allow their separation. J2, J3, and J4 sets are older than J1 sets. By analogy with experimentally produced internal fractures, the easterly decrease in dihedral angle associated with the older sets resulted from an easterly decrease in the magnitude of the causative stress system, the effective minimum principal stress of which was tensile and approximately parallel to fold axes. This stress system was a residual of the orogenic system modified by postorogenic horizontal extension related to uplift. After the older joints had formed, further uplift led to the maximum principal stress becoming normal to bedding and to the development of J1 joints.