late precambrian u pb ages for the brookville gneiss southern new brunswick tonalitic orthogneiss from the brookville gneiss in southern new brunswick has an igneous protolith age of 605 pm 3 ma based on u pb dating of zircon metamorphic titanite from the same sample gives a minimum age of 564 pm 6 ma for upper amphibolite facies metamorphism of the unit based on u pb analyses of single detrital zircons a maximum sedimentary protolith age of about 641 ma is suggested for associated paragneiss these ages indicate that the igneous protolith of the orthogneiss was at most 35 ma younger than the sedimentary rocks it intruded and that the brookville gneiss is younger than the green head group to which it was previously considered basement both orthogneiss and paragneiss in the brookville gneiss contain proterozoic and archean detrital zircon grains suggesting an old heterogeneous continental source we conclude that the brookville gneiss does not represent the basement to the avalon terrane

the pipestone pond complex central newfoundland complex magmatism in an eastern dunnage zone ophiolite ophiolitic rocks are preserved in both the notre dame and exploits subzones in the dunnage zone of the newfoundland appalachians ophiolites in the exploits subzone are generally less well preserved and exposed than their notre dame subzone counterparts and consequently have received less attention in the literature the pipestone pond complex is an exploits subzone ophiolitic sequence which outcrops on the western side of a structural window through the exploits subzone into the underlying gander zone it includes a basal harzburgite which passes upwards into a cumulate pyroxenite and gabbro sequence and thence into isotropic gabbro intruded by pegmatitic gabbro diabase and plagiogranite there is no sheeted dyke unit pillow lava occurs at the top of the sequence but is not observed to be in stratigraphic contact with the intrusive rocks the ophiolitic rocks are structurally disrupted and no single cross section traverses the complete ophiolitic stratigraphy although the stratigraphic sequence of

spatial and temporal variations in active layer thawing and their implication on runoff generation in peat covered permafrost terrain 1 the distribution of frost table depths on a peat covered permafrost slope was examined in a discontinuous permafrost region in northern canada over 4 consecutive years at a variety of spatial scales to elucidate the role of active layer development on runoff generation frost table depths were highly variable over relatively short distances 0 25 1 m and the spatial variability was strongly correlated to soil moisture distribution which was partly influenced by lateral flow converging to frost table depressions on an interannual basis thaw rates were temporally correlated to air temperature and the amount of precipitation input simple simulations show that lateral subsurface flow is governed by the frost table topography having spatially variable storage that has to be filled before water can spill over to generate flow downslope in a similar manner that bedrock topography controls subsurface flow however unlike the bedrock surface the frost table is variable with time and strongly influenced by the heat transfer involving water therefore it is important to understand the feedback between thawing and subsurface water flow and to properly represent the feedback in hydrological models of permafrost regions

redefinition of the wild bight group newfoundland implications for models of island arc evolution in the exploits subzone the wild bight group and correlative plutonic rocks of the south lake igneous complex comprise one of the accreted ordovician peri gondwanan oceanic terranes of the newfoundland appalachians recent field work and isotopic ages from the eastern wild bight group require that the stratigraphic sequence be redefined a package of bimodal volcanic rocks which forms the oldest part of the group and contains all of its volcanogenic massive sulphide deposits is redefined as the glovers harbour formation this formation is correlative with intra oceanic ophiolitic sequences elsewhere in the exploits subzone previous stratigraphic nomenclature for the upper wild bight group is largely retained although the lithological variation within and spatial distribution of the omega point seal bay brook and pennys brook formations are revised and the side harbour formation is included as part of the seal bay brook formation the upper wild bight group is interpreted to represent a second and distinct arc sequence

the chemistry of river lake systems in the context of permafrost occurrence mongolia valley of the lakes part i analysis of ion and trace metal concentrations abstract this study provides a description of water chemistry in river lake systems located in central mongolia at the borderline of permafrost occurrence the analysis involved water samples collected from two river lake systems baydrag river boon tsagaan lake system and shargalyuut tuyn rivers orog lake system in the water samples ions and trace elements were detected and quantified additionally the parameters of ph electrical conductivity sec total dissolved solids tds and total organic carbon toc were determined principal component analysis pca was performed on the sample results water chemistry is mostly influenced by geochemical and hydrometeorological processes permafrost thawing could increase the concentration of nitrogen nh4 no3 as well as na and ca2 cl and so42 however it may also be an effect of other factors such as livestock farming seasonal drying out of lakes e g lake orog may also influence water chemistry by deflation of evaporites from exposed lake beds and at the same time with lower concentration of chemical compounds in water the pca shows that water samples can be divided into two groups the first group contains lake samples where water chemistry is shaped by prevailing evaporation processes whereas the second includes samples from rivers and springs water chemistry of the latter is predominantly influenced by geochemical and hydro meteorological processes

brunswick subduction complex in the canadian appalachians record of the late ordovician to late silurian collision between laurentia and the gander margin of avalon the brunswick subduction complex in the new brunswick part of the canadian appalachians records the late ordovician to late silurian collision between laurentia and the gander margin of avalon the brunswick complex is anomalously well preserved compared with equivalent rocks and structures elsewhere owing to its unique position in the deepest part of the quebec reentrant of the laurentian margin this part of the margin experienced less underthrusting and exhumation and overprinting by orogen parallel faulting than the adjacent promontories where collision started earlier the early southeast to east vergent thrust related structures represent a progressive d1 deformation that formed in response to northwestward subduction of the previously extended gander margin and subsequent tectonic unroofing of the subduction complex the original shallow northwestward dipping envelope to s1 was deformed in the late silurian by d2 upright folds and associated shear zones into a steep belt during terminal collision the d2 structures probably formed in response to sinistral transpression together d1 and d2 indicate that convergence was oblique and sinistral most rocks incorporated in the subduction complex formed in the tetagouche back arc basin that evolved from rifting of an arenig magmatic arc built on the gander margin into a wide marginal basin subduction was initiated in the late ordovician 455 ma in the back arc basin following collision of the middle ordovician popelogan arc with laurentia in the caradoc shortly after its opening in the late arenig 473 ma the closure history of the iapetus ocean involved more than one subduction zone and arc continent collision and rivals the southwestern pacific ocean in its complexities

silurian cover late precambrian early ordovician basement and the chronology of silurian orogenesis in the hermitage flexure newfoundland appalachians

geochemistry of upper cambrian lower ordovician black shale along a northeastern appalachian transect samples of upper cambrian to lower ordovician black shale collected in a transect extending across the canadian appalachians from the humber zone in quebec the gander and avalon zones in new brunswick to the meguma zone in nova scotia were analyzed for 40 elements including rare earths these geochemical data lend support to previously established plate tectonic models of the region they also provide information on provenance and depositional environments of sediments that are too fine grained for more traditional mineralogical and sedimentological studies generally high al 2 o 3 contents high al ti values and steep rare earth element ree distribution patterns are consistent with a continental margin depositional setting for shale from the humber and meguma zones on opposite sides of the iapetus ocean generally higher k 2 o contents lower la th values and lower absolute ree abundances distinguish shale of the humber zone deposited on the laurentian margin from that deposited in the meguma zone on the gondwanan margin high la th values indicate a similar gondwanan source for shale from both the meguma and avalon zones shale from the gander zone contains less al 2 o 3 at increasing distances from its boundary with the avalon zone low al ti and less fractionated ree distribution patterns suggest a greater component of volcanic detritus in shale of the avalon and gander zones the presence of distinctive balto scandian signatures high u v and mo in shale of the avalon and northwestern gander zones is possibly related to deposition in isolated peri gondwanan back arc basins during a highstand of sea level

stable isotopic and geochemical characteristics of groundwater in kherlen river basin a semi arid region in eastern mongolia summary inorganic solute ion concentrations and stable isotopes of oxygen and hydrogen in groundwater river water and precipitation were investigated to gain insight into the groundwater recharge process in the kherlen river basin a semi arid region in eastern mongolia the solute constituents in the river water main stream were of ca hco3 type spatially invariant and low in concentration groundwater in the upstream region was also characterized by a ca hco3 type though all ion concentrations were higher than in the river water on the other hand the chemical composition of the groundwater in the midstream region southern and eastern was spatially variable and the na mg2 cl and hco 3 concentrations were considerably higher than in the river water and upstream groundwater the stable isotopic compositions showed an evaporation effect on the groundwater and river water as well as an altitude effect in the precipitation and river water preferential recharge by relatively large rainfall events is thought to have caused the depleted isotopic ratio in the groundwater in the dry regions the stable isotope chemical and hydrological data suggest that the main stream water of the kherlen river is recharged by precipitation that falls in a headwater region at an altitude of more than 1650 m and that the interaction between the groundwater and river water is not dominant in the midstream and downstream regions of the river basin

magmatic affinity of modern and ancient subalkaline volcanic rocks determined from trace element discriminant diagrams when dealing with ancient subalkaline volcanic rocks the alkali total iron magnesium afm diagram is of limited use in assigning a tholeiitic versus calc alkaline affinity because these eleme

polycyclic evolution of the late neoproterozoic basement in the hermitage flexure region southwest newfoundland appalachians new evidence from the cinq cerf gneiss abstract the cinq cerf gneiss represents one of the oldest tectonic elements yet documented within the avalonian basement complex of the hermitage flexure region of the newfoundland appalachians this gneiss is a composite unit that includes both supra crustal and granitic gneisses the latter having an igneous crystallization age of 675 12 11 ma the timing of the gneiss forming event d1 polyphase deformation is constrained by the protolith age of the orthogneiss and the 584 7 6 ma crystallization age of granodiorite intrusive into gneiss the emplacement of the granodiorite is coeval with the previously dated 585 ma eruption of felsic tuff within nearby low grade stratified elements of the pre silurian basement north of the grand bruit fault zone gbfz adding support to models of a late neoproterozoic basement cover relationship between the gneiss and the low grade volcano sedimentary sequence younger neoproterozoic magmatism in the gneissic basement is recorded by emplacement of 557 14 5 ma gabbro and the intrusion of 547 2 7 ma diorite dykes the latter have a recrystallized tectonic fabric that hosts 448 9 3 ma titanite peak appalachian cycle overprinting of the cinq cerf gneiss occurred in mid to late silurian time and commenced with high temperature deformation d2 of the gneiss associated with synkinematic intrusion of western head granite at 431 5 1 ma mafic dyke swarms that intrude the gneiss and the granite contain 420 3 ma titanite this age reflects new growth during silurian retrogression and mylonitization of the mafic dykes the d3 mylonitization is widespread and linked to thrusting of the cinq cerf gneiss along the gbfz during the 420 418 ma closure of the northerly adjacent silurian volcano sedimentary cover basin new data bearing on the late neoproterozoic record of the basement block of the western hermitage flexure further demonstrates similarities in magmatic stratigraphic and metallogenic record documented in avalonian rocks of east newfoundland s connaigre burin and avalon peninsulas pointing to a neoproterozoic linkage with the rocks in these areas the early to mid paleozoic history of the hermitage flexure basement indicates that during that time the basement block evolved as a terrane separate from the avalon zone sensu stricto

la isla de gorgona colombia a petrological enigma a wide range of intrusive wehrlite dunite gabbro and olivine gabbro and extrusive komatiites picrites and basalts igneous rocks are found on the small pacific island of gorgona the island is best known for its 90 ma spinifex textured komatiites the only true phanerozoic komatiites yet discovered early work led to suggestions that the rocks of the island formed at a mid ocean ridge however more recent research supports an origin as part of a hot mantle plume derived oceanic plateau one of the main lines of evidence for this origin stems from the inferred high mantle source temperatures required to form the high mgo n15 wt komatiites and picrites another remarkable feature of the island considering its small size 8 2 5 km is the degree of chemical and radiogenic isotopic heterogeneity shown by the rocks this heterogeneity requires a mantle source region with at least three isotopically distinctive source regions two depleted and one enriched although these mantle source regions appear to be derived in significant part from recycled oceanic crust and lithosphere enrichments in 187os 186os and 3he in gorgona lavas and intrusive rocks suggest some degree of transfer of material from the outer core to the plume source region at dw modelling reveals that the komatiites probably formed by dynamic melting at an average pressure of 3 4 gpa leaving residual harzburgite trace element depletion in gorgona ultramafic rocks appears to be the result of earlier deeper melting which produced high mgo trace element enriched magmas the discovery of a trace element enriched picrite on the island has confirmed this model gorgona accreted onto the palaeocontinental margin of northwestern south america in the eocene and palaeomagnetic work reveals that it was formed at 26 8s it has been proposed that gorgona is a part of the caribbean colombian oceanic plateau ccop however the ccop accreted in the late cretaceous and was derived from a more equatorial palaeolatitude this evidence and differing geochemical signatures strongly suggests that gorgona and probably other coastal oceanic plateau sequences in colombia and ecuador belong to a completely different oceanic plateau to the ccop

u pb ages geochemistry and tectonomagmatic history of the cambro ordovician annidale group a remnant of the penobscot arc system in southern new brunswick 1this article is one of a series of papers published in this cjes special issue in honour of ward neale on the theme of appalachian and grenvillian geology the penobscot arc system of the northeastern appalachians is an early cambrian to early tremadocian ca 514 485 ma ensialic to ensimatic arc back arc complex that developed along the margin of the peri gondwanan microcontinent ganderia remnants of this paleozoic arc system are best preserved in the exploits subzone of central newfoundland cor relative rocks in southern new brunswick are thought to occur in the ca 514 ma mosquito lake road formation of the ellsworth group and ca 497 493 ma annidale group however in the past the work that has been conducted on the latter has been of a preliminary nature new data bearing on the age and tectonic setting of the annidale group provides more conclusive evidence for this correlation the annidale group contains subalkaline tholeiitic to transitional basalts to basal tic andesites picritic tuffs and calc alkaline to tholeiitic felsic dome complexes that have geochemical signatures consistent with suprasubduction zone magmatism that was likely generated in a back arc basin new u pb ages establish that the late cambrian to early tremadocian annidale group and adjacent ca 541 ma volcanic rocks of the belleisle bay group in the new river belt were affected by a period of younger magmatism ranging in age from ca 479 467 ma this provides im portant constraints on the timing of tectonism in the area a ca 479 ma age for the stewarton gabbro that stitches the faulted contact between the annidale and belleisle bay groups demonstrates that structural interleaving and juxtaposition occurred during early tremadocian time which closely coincides with the timing of obduction of penobscottian back arc ophiolites onto the ganderian margin in newfoundland resume le systeme d arc penobscot du nord est des appalaches est un complexe d arc d arriere arc ensialique a ensima tique datant du cambrien precoce au tremadocien precoce 514 485 ma qui s est developpe le long de la bordure peri gondwannienne du microcontinent ganderia des lambeaux de ce systeme d arc paleozoique sont le mieux conserves dans la sous zone exploits du centre de terre neuve des roches correlatives dans le sud du nouveau brunswick seraient presen tes dans la formation de mosquito lake road 514 ma du groupe d ellsworth et dans le groupe d annidale 497 493 ma toutefois par le passe le travail effectue sur ce dernier groupe n a ete que preliminaire de nouvelles donnees sur l ge et l environnement tectonique du groupe d annidale fournissent des evidences plus concluantes de cette correlation le groupe d annidale contient des basaltes a des andesites basaltiques subalcalins tholeiitiques a intermediaires des tufs picritiques et des complexes de domes felsiques calco alcalins a tholeiitiques possedant des signatures geochimiques qui concordent avec un magmatisme de zone de suprasubduction probablement generee dans un bassin d arriere arc de nou veaux ges u pb ont etabli que le groupe d annidale cambrien tardif a tremadocien precoce et les roches volcaniques ad jacentes du groupe de belleisle bay 541 ma dans la ceinture de new river ont ete affectes par une periode de magmatisme plus jeune datant d environ 479 a 467 ma ces donnees fournissent des contraintes importantes sur le moment du tectonisme dans la region un ge d environ 479 ma pour le gabbro de stewarton qui reunit le contact de faille entre les groupes d annidale et de belleisle bay demontre que l imbrication et la juxtaposition structurales ont eu lieu au debut du tremadocien ce qui coincide de pres avec le moment de l obduction des ophiolites d arriere arc de penobscot par dessus la bordure de ganderia a terre neuve traduit par la redaction

the use of sequential extraction to determine the distribution and modes of occurrence of mercury in permian huaibei coal anhui province china sequential extraction tests using a flow injection mercury system fims were done on 34 samples collected from the number 3 4 5 7 and 10 coal seams in the huaibei coalfield average total mercury hg concentrations for the seams were 0 13 0 18 0 54 0 34 and 0 19 mg kg respectively the average value for all of the coal samples was 0 26 mg kg which is higher than most chinese and u s coals six modes of hg occurrence were recognized including water leachable ion exchangeable organic bound carbonate bound silicate bound and sulfide bound hg with rare exception little hg was found in water soluble ion exchangeable or carbonate bound forms sulfide bound hg and organic bound hg dominated seams 3 4 and 10 whereas silicate bound hg dominated seams 5 and 7 the relatively high hg values observed in seams 5 and 7 especially in parting samples are attributed to hg enrichment by magmatic intrusions

petrogenesis and paleotectonic history of the wild bight group an ordovician rifted island arc in central newfoundland the wild bight group wbg is a sequence of early and middle ordovician volcanic subvolcanic and epiclastic rocks part of the dunnage tectonostratigraphic zone of the newfoundland appalachians a detailed geochemical and nd isotopic study of the volcanic and subvolcanic rocks has been carried out to determine the geochemical characteristics of the rocks interpret their palcotectonic environments and constrain their petrogenetic history the lower and central stratigraphic levels of the wbg contain mafic volcanic rocks with island arc geochemical signatures including lree enriched are tholeiites with e nd t 0 1 to 2 2 type a i lree depleted arc tholeiites with e nd t 5 6 to 7 1 type a ii and an unusual suite of strongly incompatible element depleted tholeiites in which e nd t ranges from 0 9 to 4 6 and is negatively correlated with147sm 144nd type a iii high silica low k rhyolites occur locally in the central part of the stratigraphy associated with mafic rocks of arc affinity and have e nd t 4 7 to 5 4 the upper stratigraphic levels of the wbg dominantly contain rocks with non arc geochemical signatures including alkalic basalts with e nd t 4 6 to 5 5 type n i strongly lree and incompatible element enriched tholeiites that are transitional between alkalic and non alkalic rocks with e nd t 4 4 to 7 0 type n ii and rocks with flat to slightly lree enriched patterns and e nd t 5 1 to 7 4 type n iii rocks with non arc and arc signatures are locally interbedded near the stratigraphic type of the wbg nd isotopic data in the type a i and a ii rocks are generally compatible with mixing partial melting models involving depleted mantle variably contaminated by a subducted crustally derived sediment the petrogenesis of type a iii rocks must involve source mixing and multi stage partial melting but the details are not clear the geochemistry and nd isotope data for types n i n ii and n iii rocks are compatible with petrogenetic models involving variable partial melting of a source similar to that postulated for modern oceanic island basalts comparison of the wbg with modern analogues suggests a 3 stage developmental model stage 1 island arc volcanism eruption of type mafic volcancs stage 2 arc rifting continued eruption of type a i a i eruption of types a ii and a iii mafic volcanics and high silica low k rhyolites and stage 3 back arc basin volcanism continued minor eruption of type a i basalts eruption of types n i n ii n iii basalts stages 1 and 2 volcanism involved partial melting of subduction contaminated mantle while stage 3 volcanism utilized depleted mantle sources not affected by the subducting slab this model provides a basis for interpreting coeval sequences in central newfoundland and a comparative framework for some early paleozoic oceanic volcanic sequences elsewhere in the appalachian orogen

the kingston terrane southern new brunswick canada evidence for an early silurian volcanic arc the fault bounded kingston terrane of southern new brunswick consists of felsic and less abundant mafic volcaniclastic rocks and flows and minor interbedded sedimentary rocks of the kingston group intruded by mainly granitic plutons and abundant younger mafic sheets the granitic plutons form about half of the terrane and are characterized by fine grain size and typically granophyric and porphyritic textures indicative of high level emplacement mafic sheets were emplaced in the granitic plutons and parallel to primary layering in the kingston group which is typically steeply dipping and trends northeast to north northeast hence in contrast to some earlier interpretations the kingston terrane does not consist of a bimodal dike complex the kingston group granitic rocks and mafic sheets contain mineral assemblages consistent with metamorphism to upper greenschist lower amphibolite facies new u pb zircon ages of 442 6 ma from a dacitic tuff unit and 437 10 ma from a granitic pluton corroborate previous u pb dates that had suggested that the volcanic and granitic rocks in the kingston terrane are early silurian rather than precambrian as had been earlier assumed the felsic volcanic and granitic rocks are interpreted to be comagmatic on the basis of their field relationships and similar u pb ages and chemical character compositions of both the felsic rocks and less abundant mafic and intermediate and mafic rocks are consistent with calc alkalic affinity and emplacement in a continental margin volcanic arc herein termed the kingston arc a u pb date of 435 5 ma was also obtained from compositionally similar granite that forms a dike in an adjacent fault bounded amphibolite facies metasedimentary unit the similarity in age and composition of the granite dike suggests a link between these metasedimentary rocks and the kingston terrane possibly as part of an accretionary complex if so its location southeast of the kingston terrane indicates that subduction was to the present northwest mafic sheets in the kingston terrane are tholeiitic but have some arc like characteristics consistent with their origin in a former arc setting but the sheets were likely emplaced in a subsequent extensional setting the compositional similarity of the mafic sheets to late silurian mafic volcanic rocks and plutons of the coastal maine magmatic province suggests that they may be related a possible model for evolution of the kingston terrane is proposed wherein the kingston group and related granite formed in an early silurian arc on the margin of ganderia as represented by the new river terrane of late precambrian and early paleozoic age northwestward subduction culminated in collision between the kingston arc and a continental block now represented by the brookville terrane to the southeast subsequent transpressive mo tions in the late silurian may have been responsible for the crustal scale extensional environment in which the coastal maine magmatic province was formed including emplacement of mafic dikes into the deformed former kingston arc transpressive motions related to juxtaposition of the avalon and meguma terranes with the previously accreted more inboard terranes continued through the devonian and into the carboniferous

the chemistry of river lake systems in the context of permafrost occurrence mongolia valley of the lakes part ii spatial trends and possible sources of organic composition abstract the chemistry of river lake systems located in central mongolia near the southern border of permafrost occurrence has not been well studied the main aim of this paper is to summarize patterns in water chemistry in supply springs rivers and lakes in relation to permafrost occurrence as well as other natural and anthropogenic impacts the analyses involved water samples taken from two river lake systems the baydrag river boon tsagaan lake system and the shargalyuut tuyn rivers orog lake system total organic carbon toc and polycyclic aromatic hydrocarbons pahs were detected and quantified other organic compounds such as organic halogen compounds phthalates and higher alkanes were also noted the main factors which influence differences in toc concentrations in the water bodies involve permafrost occurrence mainly because compounds are released during active layer degradation in the upper reach of the tuyn river and by intensive livestock farming in river valleys and in the vicinity of lakes in relation to the concentrations of pahs high variability between samples 300 ng l 1 indicates the influence of thermal water and local geology structures e g volcanic and sedimentary deposits as well as accumulation of suspended matter in lakes transported during rapid surface runoff events the monitoring of toc as well as individual pahs is particularly important to future environmental studies as they may potentially reflect the degradation of the environment therefore monitoring in the valley of the lakes should be continued particularly in the light of the anticipated permafrost degradation in the 21st century in order to collect more data and be able to anticipate the response of river lake water chemistry to changes in permafrost occurrence

neoproterozoic and cambrian arc magmatism along the eastern margin of the victoria lake supergroup a remnant of ganderian basement in central newfoundland abstract the eastern margin of the composite and structurally complex victoria lake supergroup has previously been mapped where the silurian rogerson lake conglomeratic rocks unconformably overlie cambrian tally pond volcanic rocks however the recognition that the form of this contact changes between an unconformity and a brittle ductile fault in conjunction with the neoproterozoic age of the crippleback intrusive suite dictate that the above interpretation of the nature of this margin requires revision these discrepancies are resolved by the recognition of a neoproterozoic largely bimodal volcanic sequence sandy brook group which is unconformably overlain by rogerson lake rocks to the east with these combined units in fault contact with the tally pond group to the west the sandy brook group and crippleback intrusive suite form a terrane of ca 563 ma rocks with continental arc like geochemical signatures the distinctly negative nd 563 values for the felsic rocks mean 3 of this terrane imply derivation from a crystalline basement older than the largely pan african crust that underlies contemporaneous volcanic rocks in west avalonia but similar to that inferred for the gander zone thus this terrane is likely to be the leading edge of the peri gondwanan microcontinent ganderia the ca 511 ma tally pond group arc magmatism represent some of the oldest products of iapetean subduction in newfoundland although the tally pond group are only observed to be in fault contact with the ca 50 million year older sandy brook group the high proportion of felsic volcanic rocks sandy brook crippleback age inherited zircons and pb isotopic data all support the inference that the tally pond group was formed on sandy brook crippleback continental crust

u pb ages and tectonomagmatic relationships of early ordovician low ti tholeiites boninites and related plutonic rocks in central newfoundland canada the wild bight group wbg and south lake igneous complex slic together comprise one of the ordovician accreted oceanic terranes of the central mobile belt of the newfoundland appalachians combined detailed mapping geochemistry sm nd isotopic studies and u pb geochronology have shown that sheeted dykes and hornblende diorite and tonalite plutons of the slic are genetically related to a discrete package of volcanic rocks in the wbg these igneous rocks are geochemically isotopically and temporally distinct from volcanic rocks in the rest of the wbg plutonic rocks of the slic range in age from 486 3 ma to 489 3 ma and a cross cutting gabbro dyke gives a minimum age of 486 4 ma for the related volcanic sequence volcanic rocks in the rest of the wbg sequence are predominantly younger than 472 3 ma the older volcanic sequence of the wbg and the slic occur as fault bounded packages interleaved within the younger wbg sequence a conformable stratigraphic relationship between the older and younger sequences of the wbg has not been demonstrated the mafic rocks of the older package include boninites and low ti high mg tholeiitic island arc basalts which are interpreted to be genetically related and normal island arc tholeiites iat the high mg mafic rocks are interpreted to have formed in an extensional setting during subduction zone initiation and the normal iat are thought to represent stabilisation of the volcanic front the associated high si low k rhyolite and tonalite are interpreted to be the products of secondary melting at the base of thickened early arc crust sm nd isotopic compositions indicate that the characteristic trace element signature of the boninites developed at or near their time of generation and was not a long lived characteristic of the source region the boninites and low ti tholeiites are interpreted to have originated from a similar source which was metasomatized by different subduction related components apparent decoupling of sm nd geochemical and isotopic compositions suggests that these very depleted rocks may be recording the effect of subduction zone processes not yet fully understood

u pb geochronological constraints on precambrian stratified units in the avalon composite terrane of nova scotia canada tectonic implications concordant u pb ages of detrital zircons in several proterozoic units in the avalon composite terrane of nova scotia along with previously published data indicate that deposition of low and high grade stratified units in the cobequid highlands gamble brook formation and central cape breton island variously assigned to the george river group or george river metamorphic suite and the bras d or gneiss started after 977 ma extended through a period of volcanic activity between 694 and 637 ma and ended before the 629 612 600 ma volcanic activity associated with deposition of the georgeville and jeffers groups in the antigonish and cobequid highlands and the east bay hills and coxheath groups in southern cape breton island these age data along with u pb analyses of metamorphic and igneous zircon and monazite also constrain three late proterozoic tectonothermal events i oblique sinistral ductile shear deformation and greenschist amphibolite facies metamorphism probably occurred between 694 an

the role of soil pipes as a slope runoff mechanism subarctic yukon canada pipeflow in subarctic slopes provides a preferential runoff mechanism that bypasses the soil matrix rapidly conveying water to the stream extensive soil piping occurs in the central wolf creek basin yukon at the interface of the organic and mineral horizons flow in these pipes are ephemeral transmitting water only when the water table is within or above the zone where pipes occur during snowmelt pipeflow began several days after the onset of surface runoff pipeflow contribution increased until ground thaw lowered the water tables leaving matrix flow within the organic layer as the dominant mode of runoff pipeflow accounted for 21 of runoff during the 15 day melt period of 1997 following melt pipeflow recurred only during two intense summer rainstorms each yielding different pipeflow response characteristics during melt pipeflow closely followed the daily snowmelt cycles and responded earlier than the integrated slope runoff in the summer pipeflow hydrographs rose and fell much quicker than direct storm runoff from the entire slope which was dominated by fast matrix flow within the organic layer pipeflow contributing areas were relatively small but their extent changed with hillslope wetness analysis revealed that the manning flow formula can be combined with contributing areas to simulate pipeflow discharges unlike temperate environments where frozen ground is not a factor the frost table position significantly controls the position of the phreatic surface and must be considered in any models of pipeflow in permafrost slopes

the ellsworth terrane coastal maine geochronology geochemistry and nd pb isotopic composition implications for the rifting of ganderia the ellsworth terrane is one of a number of fault bounded blocks that occur along the eastern margin of ganderia the westernmost of the peri gondwanan domains in the northern appalachians that were accreted to laurentia in the paleozoic geologic relations detrital zircon ages and basalt geochemistry suggest that the ellsworth terrane is part of ganderia and not an exotic terrane in the penobscot bay area of coastal maine the ellsworth terrane is dominantly composed of bimodal basalt rhyolite volcanic sequences of the ellsworth schist and unconformably overlying castine volcanics we use new u pb zircon geochronology geochemistry and nd and pb isotopes for these volcanic sequences to constrain the petrogenetic history and paleotectonic setting of the ellsworth terrane and its relationship with ganderia u pb zircon geochronology for rhyolites indicates that both the ellsworth schist 508 6 0 8 ma and overlying castine volcanics 503 5 2 5 ma are middle cambrian in age two tholeiitic basalt types are recognized type tb 1 basalt present as pillowed and massive lava fl ows and as sills in both units has depleted la and ce la nd n 0 53 0 87 values fl at heavy rare earth element ree values and no positive th or negative ta anomalies on primitive mantle normalized diagrams in contrast type tb 2 basalt present only in the castine volcanics has slightly enriched lree la yb n 1 42 2 92 values and no th or ta anomalies both basalt types have strongly positive e nd 500 values tb 1 7 9 8 6 tb 2 5 6 7 0 and relatively enriched pb isotopic compositions 206

tectono stratigraphic terranes in cape breton island nova scotia implications for the configuration of the northern appalachian orogen cape breton island is divided into four terranes on the basis of contrasts in pre carboniferous geology the blair river complex in the north is an exposure of north american grenvillian basement analogous to the humber zone basement in newfoundland ordovician to devonian metavolcanic metasedimentary gneissic and granitic rocks of the aspy terrane are correlative with parts of the gander terrane of newfoundland and new brunswick the bras d9or terrane characterized by low pressure gneisses a carbonate clastic platform sequence and late precambrian early cambrian plutons may be correlative with units previously included in the gander terrane in southern newfoundland and the avalon terrane in southern new brunswick the mira terrane in southeastern cape breton island including late precambrian to early cambrian volcanic and sedimentary sequences and fossiliferous cambrian ordovician units is clearly part of the avalon terrane therefore with the exception of the dunnage terrane which is not represented in cape breton island the terranes of newfoundland continue through cape breton island they are offset to the northwest to the mainland part of the appalachian orogen in new brunswick

subsurface flow velocities in a hillslope with lateral preferential flow 1 our understanding of hillslope subsurface flow relies on assumptions about how storm characteristics affect the hillslope runoff response experiments in hillslopes dominated by preferential flow features often show that runoff is dynamic and is affected by antecedent conditions rainfall conditions and position of the slope we applied tracers to a hillslope under natural and steady state flow boundary conditions to determine the relationship between lateral tracer velocities and various hillslope lengths and storm indicators tracer velocities were similar to the fastest velocities measured in other similar experiments the velocities were dependent on the boundary conditions and slope length and the subsurface flow velocity was most closely related to the 1 h rainfall intensity unlike some studies there was little correlation between our measured flow velocities and storm volume or antecedent conditions we attributed this to the hillslope characteristics and the relatively consistent wet antecedent conditions during the experiments this experiment showed that the connectivity of the hillslope preferential flow network is an important factor governing the average subsurface flow velocity

slope runoff processes and flow generation in a subarctic subalpine catchment hillslope runoff was studied in a subarctic subalpine environment to improve understanding of runoff generation processes and the mechanisms whereby water moves from hillslopes to the stream runoff characteristics of four hillslopes were examined between 1997 and 1999 each with distinct soils frost topography and vegetation lateral fluxes were confined to hillslopes with porous organic soils overlying less permeable mineral substrates setting up a two layer flow system whereby most drainage occurs as quickflow in the porous organic layer as matrix flow and or as preferential flow in pipes rills and interconnected surface depressions during snowmelt meltwater infiltrated and percolated the porous frozen organic layers with little resistance percolation ceased at the organic mineral interface due to the impermeable nature of frozen mineral soils forming a perched saturated zone and initiating runoff snowmelt runoff was greater on slopes with greater snow water equivalent and reduced organic layer thickness in summer runoff was greatest on slopes where wet conditions were sustained by inflow stormflow hydrographs responded rapidly to rainfall while exhibiting extended recessions compared with temperate regions where sustained inflow occurred the recession limb showed two segments to reflect different source areas of stormflow production recession analysis was used to quantify contributing areas which were highly variable and controlled largely by hillslope wetness and organic layer properties results indicate that the concept of variable source area for runoff generation applies to subarctic subalpine catchments

archean metavolcanics from the rouyn noranda district abitibi greenstone belt quebec 2 mobility of trace elements and petrogenetic constraints qualitative evaluation of altered mafic pillows from the rouyn noranda district of the abitibi metavolcanic belt reveals that for low grade metamorphism the high field strength elements hfs zr y ti and the rare earth elements ree are immobile however where alteration is extreme the ree elements are leached and redeposited by carbonate rich and k rich metasomatic fluids whilst zr y and zr ti remain unchanged rubidium ba and to a lesser extent sr are mobile at all levels of alteration however provided certain filters are applied the original geochemical values of the lavas for the alkaline elements the hfs elements and the ree can be defined the geochemical variations thus identified for the volcanic series of the rouyn noranda district are ascribed to a combination of contamination and fractional crystallization of a primitive tholeiitic magma

tracing variability of run off generation in mountainous permafrost of semi arid north eastern mongolia the headwaters of mountainous discontinuous permafrost regions in north eastern mongolia are important water resources for the semi arid country but little is known about hydrological processes there run off generation on south facing slopes which are devoid of permafrost has so far been neglected and is totally unknown for areas that have been affected by recent forest fires to fill this knowledge gap the present study applied artificial tracers on a steppe vegetated south facing and on two north facing slopes burned and unburned combined sprinkling and dye tracer experiments were used to visualize processes of infiltration and water fluxes in the unsaturated zone on the unburned north facing slope rapid and widespread infiltration through a wet organic layer was observed down to the permafrost on the burned profile rapid infiltration occurred through a combusted organic and underlying mineral layer stained water seeped out at the bottom of both profiles suggesting a general tendency to subsurface stormflow ssf ongoing ssf could directly be studied 24 h after a high intensity rainfall event on a 55 m hillslope section in the burned forest measurements of water temperature proved the role of the permafrost layer as a base horizon for ssf repeated tracer injections allowed direct insights into ssf dynamics a first injection suggested rather slow dispersive subsurface flow paths whereas 18 h later a second injection traced a more preferential flow system with 20 times quicker flow velocities we speculate that these pronounced ssf dynamics are limited to burned slopes where a thermally insulating organic layer is absent on three south facing soil profiles the applied tracer remained in the uppermost 5 cm of a silt rich mineral soil horizon no signs of preferential infiltration could be found which suggested reduced biological activity under a harsh dry and cold climate instead direct observations distributed tracers and charcoal samples provided evidence for the occurrence of overland flow copyright 2014 john wiley sons ltd

mineral deposits of canada a synthesis of major deposit types district metallogeny the evolution of geological provinces and exploration methods wayne d goodfellow editor 1 068 pp geological association of canada mineral deposits division special publication no 5 2007 hardcover isbn 13 978 1 897095 24 9 price members cdn 60 00 non members cdn 80 00 following in the footsteps of other landmark reviews of major ore producing countries such as australia hughes 1990 solomon and groves 1994 and south africa anhaeusser and maske 1986 this substantial 1 000 pages monograph is a great achievement that should be in every geologic research library in the world in many ways it sets a new standard most notably in that all figures and photographs are in color and that the entire volume is available in electronic form both as an included dvd and mostly on the gac website it is common in such compendia to have a spectacular cover photo or frontispiece to catch the reader s attention and this book does not disappoint the frontispiece photo is of a 61 8 kg sample from the dome mine timmins ontario and is stated to contain 20 wt percent gold at today s prices the gold alone would be worth 1 5 million dollars

age and implications of early ordovician arenig plutonism in the type area of the bay du nord group dunnage zone southern newfoundland appalachians in south newfoundland an extensive tract of metamorphosed ordovician metavolcanic metasedimentary and granitoid rocks bay du nord group lies north of a late precambrian basement inlier of peri gondwanan affinity separated from the latter by silurian rocks in the bay du nord group type area the metavolcanic and metasedimentary rocks were ductilely sheared and locally fault imbricated with metagabbro prior to emplacement of the baggs hill granite herein dated at 477 6 1 8 ma some of the volcano sedimentary strata within this succession however contain foliated clasts of baggs hill granite and these strata must comprise a younger stratigraphic sequence which in this area is thrust northwestward over the older rocks the pre 477 6 1 8 ma tectonic interleaving of the dunnage zone gabbro and stratified rocks is significantly earlier than the llandovery early salinic recumbent folding and thrusting of middle ordovician exploits subzone rocks in the east central hermitage flexure in both area

geochronology of ophiolites of the newfoundland appalachians precise u pb zircon ages 2 errors are reported for four ophiolite complexes from the newfoundland appalachians zircons from trondhjemite from blow me down mountain bay of islands complex give an age of five points those from gabbro from blow me down brook give a minimum 207pb 206pb age of 480 ma one point confirming that this is the age of the main plutonic episode these data refute previously determined latest cambrian u pb zircon and sm nd mineral rock isochron ages of 504 10 and 505 ma for the complex gabbro from the betts cove complex yielded zircon that gives an age of four points this refutes the interpretation of an earlier u pb zircon age of 463 6 ma for a trondhjemite dyke as the age of the ophiolite it was inconsistent with the presence of arenigian graptolites in the overlying snooks arm group two zircon ages from a pegmatitic and medium grained trondhjemite of the annieopsquotch complex are five points and two points zircon from trondhjemite of the pipestone pond c

the response 1958 1997 of permafrost and near surface ground temperatures to forest fire takhini river valley southern yukon territory forest fires in permafrost areas often modify ground surface conditions causing deepening of the active layer and thawing of near surface permafrost takhini river valley lies in the discontinuous permafrost zone of southern yukon territory the valley floor is covered by glaciolacustrine deposits which are locally ice rich in 1958 extensive forest fires burned most of the vegetation and the soil organic horizon in the valley but 50 km west of whitehorse 1 km2 of spruce forest adjacent to the alaska highway escaped burning permafrost beneath this stand of trees is in equilibrium with surface conditions the active layer is 1 4 m thick the base of permafrost is at 18 5 m the annual mean temperature at the top of permafrost 1 5 m is 0 8 c and the temperature gradient in permafrost is constant with depth at burned sites nearby there has been little regeneration of forest vegetation since the fire and long term permafrost degradation has occurred at one burned site the permafrost table is mor

upper cambrian to upper ordovician peri gondwanan island arc activity in the victoria lake supergroup central newfoundland tectonic development of the northern ganderian margin the exploits subzone of the newfoundland appalachians comprises remnants of cambro ordovician peri gondwanan arc and back arc complexes that formed within the iapetus ocean the exploits subzone experienced at least two accretionary events as a result of the rapid closure of the main portion of the iapetus tract the penobscot orogeny c 480 ma which juxtaposed the penobscot arc c 513 486 ma with the gander margin and c 450 ma collision of the victoria arc c 473 454 ma with the annieopsquotch accretionary tract that juxtaposed the peri laurentian and peri gondwanan elements along the red indian line the newly recognized pats pond group forms a temporal equivalent to other lower ordovician intra oceanic complexes of the penobscot arc the pats pond group c 487 ma has a geochemical stratigraphy that is consistent with rifting of a volcanic arc an ensialic setting is indicated by low end values end 0 3 to 0 5 near the stratigraphic base and its abundant zircon inheritance c 560 ma and 0 9 1 2 ga the spatial distribution of tremadocian arc back arc complexes indicates that the penobscot arc is best explained in terms of a single east dipping subduction zone this model is favored over west dipping models in that it explains the distribution of the penobscot arc elements continental arc magmatism and the obduction of back arc penobscot ophiolites without requiring subduction of the gander margin or subduction reversal the newly recognized wigwam brook group c 454 ma disconformably overlies the pats pond group and records the youngest known phase of ensialic arc volcanism end 4 1 in the victoria arc which is also related to east dipping subduction thus the penobscot and the overlying victoria arc are reinterpreted in terms of a single relatively long lived east dipping subduction zone beneath the peri gondwanan microcontinent of ganderia the cessation of arc volcanism towards the top of the wigwam brook group and the subsequent syn tectonic sedimentation in the badger group constrain the arrival of the leading edge of ganderia with the ensialic arc complexes to the laurentian margin to c 454 ma

nd isotopic characteristics of terranes within the avalon zone southern new brunswick nd isotopic data are presented for rock units in four terranes within the traditional avalon zone of southern new brunswick initial end values for igneous rocks within the caledonia terrane range from 1 6 to 4 6 whereas values for sedimentary rocks range from 8 4 to 3 6 a granite within the kingston terrane has end 438 ma 4 0 nd isotopic compositions for the kingston and caledonia terranes are similar to those of the mira terrane in cape breton island the antigonish highlands of nova scotia and plutonic rocks of eastern newfoundland each of these regions may be a dismembered part of a single terrane the avalon terrane sensu stricto initial end values for rocks from the brookville terrane range from 1 3 to 2 8 the coverdale anorthosite within the brookville terrane has a present day end value of 12 1 and a depleted mantle model age of 1 3 ga similar to mesoproterozoic anorthosites in laurentia clastic sedimentary rocks in the green head group have end 750 ma values of 2 0 and 10 9