structural evolution of the laurentian margin revisited southern quebec appalachians implications for the salinian orogeny and successor basins the laurentian margin of the appalachians is divided into external and internal zones on the basis of metamorphic and structural contrasts in the southern quebec internal zone silurian to early devonian southeast verging structures are superimposed on northwest verging structures whereas most of the external zone lacks such overprints regional backthrust faults define a major upper plate lower plate boundary the external zone rocks are in the hanging wall and internal zone rocks are in the footwall metamorphic rocks with silurian early devonian 40 ar 39 ar ages 430 410 ma characterize the lower plate to the east the saint joseph fault and the baie verte brompton line are southeastdipping normal faults that crosscut the upper plate lower plate boundary metamorphic rocks with middle ordovician 40 ar 39 ar ages 469 461 ma and rocks of the external zone both occur in the downthrown side of the saint joseph fault and the baie verte brompton line u pb and 40 ar 39 ar ages suggest that the northwest verging structures are related to ophiolite obduction and crustal thickening during the taconian orogeny ca 480 445 ma whereas the southeast verging structures formed during silurian early devonian backthrusting and normal faulting the revised structural interpretation has implications for the salinian orogeny and involves 1 southeast directed transport of the taconian crustal wedge of the upper plate followed by normal faulting and juxtaposition with the lower plate along the saint joseph fault and the baie verte brompton line and 2 the forma

gradual encroachment of a rocky shoreline by an invasive sea during the mississippian at the southeastern margin of the maritimes basin nova scotia canada onlap of a rocky shoreline by marine beds of the mississippian windsor group occurred at the southeastern margin of the composite upper paleozoic maritimes basin in central nova scotia the sedimentology of thin basal rudaceous deposits suggests that although the transgression was rapid there were times of prolonged shoreline stabil ity boulder beach deposits indicate a high energy coastline and a large marine basin clastic delta deposits were proxi mal to thick biohermal banks in shallow areas near the southeast margin of the sea while sulphate deposition was occurring basinward according to their contained biota and stratigraphic relationships the marginal banks evolved in a less saline environment than banks forming away from river inputs on paleotopographic highs located farther offshore because diversity of the biota decreases with an increase in both water depth and distance from the paleoshore and because bank development in shallow or marginal areas was apparently synchronous with evaporitic deposition in deeper or less marginal areas we conclude that both a vertical and a lateral gradient of salinity existed due to the thrusting of fluvial fresh water above salt water and its infiltration along the paleoshoreline as salinity increased with time bank building eventually aborted and sulphate deposition gave way to salt deposition in the deepest parts of the basin lastly the onlap of evaporites above marginal clastic deposits indicates that evaporite deposition occurred in a transgressive context although a gradual thinning of the water column may have simultaneously occurred due to basin infilling

petrology of garnet clinopyroxene amphibolites from mont albert gaspe quebec the mont albert mafic ultramafic complex of central gaspe quebec is generally regarded as a partial ophiolite with an underlying metamorphic sole the metamorphic rocks include a number of mineralogical and textural varieties of amphibolite including some migmatite as well as minor metasedimentary and quartzo feldspathic gneisses the most intriguing rocks in the complex are mafic to ultramafic garnet and clinopyroxene bearing amphibolites that are restricted to the vicinity of the peridotite contact these rocks have unusual fe rich si poor bulk compositions and may represent tholeiites chemically modified by interaction with fluid or melt before or during metamorphism these amphibolites are not retrograde eclogites since andesine was present throughout the metamorphic history and the clinopyroxene is not omphacitic coexisting mineral compositions and temperature estimates overlap for core rim and matrix grains of all the major phases in the garnet clinopyroxene amphibolites implying equilib

forward potential field modeling of the appalachian orogen in the gaspe peninsula quebec canada implications for the extent of rift magmatism and the geometry of the taconian orogenic wedge the nature and extent of potential source bodies associated with prominent regional scale gravity and magnetic anomalies in the northern quebec appalachians are investigated through forward modeling potential field anomalies are interpreted to be the geophysical expression of basalt flows extruded during the neoproterozoic to cambrian rifting of laurentia prior to opening of iapetus geophysi cal modeling provides substantial new constraints on seismic and structural cross sections and the map distribution of volcanism this study indicates that the volcanism was significantly more widespread than previously recognized basaltic rocks form a sheet up to 4 kilometers thick transported on the main taconic decollement most of this sheet is deeply buried and overlain by a thick pile of paleozoic sediments later tectonic modifications by backthrusting and hinterland directed normal faulting as well as by acadian strike slip faulting substantially changed the geometry of the transported volcanic rocks and the structural style both across and along the strike of the orogen the extension of the gravity anomaly under the st lawrence river also suggests that the ordovician deformation front is 20 to 30 kilometers further to the north than previously interpreted

compilation of non annually resolved holocene proxy climate records stacked holocene peatland palaeo water table reconstructions from northern britain abstract the number and range of holocene palaeoclimate reconstructions from various regions of the world have increased dramatically over the last decade the data density for many regions and proxies now offers the potential of robust regional scale reconstructions that avoid the problems of records from individual sites and improve communication between palaeoclimate subdisciplines and climate modellers however there are problems with chronological uncertainties and quantification of proxies which make compilation of multiple records difficult here we explore a stacking and tuning approach to the derivation of regional records from peatland climate proxies to test its applicability to non annually resolved terrestrial records twelve individual records from northern britain based on water table reconstructions from testate amoebae analysis were divided into four regions records were detrended normalised and compared within regions to identify clear correlative events the original chronologies of the records were tuned using both these events and independent age markers the stacked record for northern britain indicates pronounced changes to wet conditions at 3600 2760 and 1600 cal yr bp with more minor changes at 3060 2050 1260 860 550 and 260 cal yr bp the main wet phases are highly correlated with mid european lake highstands wider north atlantic climate change inferred from ocean and ice core records and solar variability tuning and stacking of non annual terrestrial palaeoclimate records is a new approach to the compilation and reconciliation of individual records within coherent climatic regions and provides a tool for upscaling of palaeoclimate records for climate model data comparisons

a three thousand year record of north atlantic climate annual band counting on three radiometrically dated stalagmites from nw scotland provides a record of growth rate variations for the last 3000 years over the period of instrumental meteorological records we have a good historical calibration with local climate mean annual temperature mean annual precipitation regional climate north atlantic oscillation and sea surface temperature sst strongest at 65 70 n 15 20 w although the correlation with the latter breaks down prior to the instrumental record this suggests that the climatic factors that force nw scottish climate and therefore our stalagmite growth varied through time and include winter nao strength the strength of the thermohaline circulation and possibly solar output spectral analysis was performed on the stalagmite growth rate time series a spectral frequency of 50 70 years is predominant in two stalagmites that were deposited from 1000 to 3000 bp a slightly longer frequency of 72 94 years is dominant from 1000 bp to present these are the same as that observed in ocean gcm output for the north atlantic region ssts our stalagmites provide high resolution precisely dated evidence of a similar periodicity predominating over the last 3000 years in a climate proxy record known to be sensitive to changes in forcing functions relevant to the north atlantic sector

a thousand year speleothem proxy record of north atlantic climate from scotland luminescent organic matter in stalagmites may form annual bands allowing growth rate to be precisely determined stalagmite growth rate is controlled by precipitation so annual bands can be used to derive long precipitation records a continuously banded stalagmite from a cave in nw scotland was used to provide a 1100 year high resolution record of precipitation the location of the cave means that precipitation is closely linked to the north atlantic oscillation for which a record is also derived this suggests that changes in the north atlantic oscillation state was an important control on european climate over the past millennium

integration and spatial analysis of high resolution geophysical and geological data eastern gaspe peninsula in the vicinity of the town of gaspe the relationships between the silurian devonian sedimentary succes sion of the gaspe belt and the humber and the dunnage zones are complex to unravel these relationships we used high resolution aeromagnetic data and regional gravimetric data coupled with field tectonostratigraphic information the magnetic vertical derivative located several magnetic anomalies associated with near surface features in the silurian devonian cover sequence in particular a conglomerate with magnetic fragments that overlies the late silurian salinic unconformity is clearly recognizable large ovoid anomalies of significant intensity located in the silurian devonian sedimentary cover area cannot be associated with any known geological feature the interpretation of the high pass and low pass filtered aeromagnetic survey indicates that the ovoid anomalies originate below the silurian devonian cover sequence the most significant of the ovoid anomalies is associated with a gravimetric anomaly it is proposed that these geophysical anomalies are probably associated with ultramafic and or volcanic rocks correlative in the subsurface with outcrops of the cambrian ordovician lithologies of the lady step complex and or the shickshock group resume dans la region de gaspe les relations entre la couverture sedimentaire siluro devonienne de la ceinture de gaspe et les zones de humber et de dunnage sont complexes pour mieux comprendre ces relations nous avons utilise des donnees aeromagnetiques de haute resolution et des donnees gravimetriques regionales appariees aux donnees tecto nostratigraphiques de terrain le gradient magnetique vertical a mis en evidence plusieurs signatures magnetiques peu profondes dans la couverture sedimentaire siluro devonienne en particulier un conglomerat a fragments magnetiques surmontant la discordance salinique du silurien tardif est aisement identifiable de grandes anomalies ovoides d intensite importante localisees dans la couverture siluro devonienne n ont pu etre associees a aucun element geologique connu le passage du leve magnetique dans des filtres passe haut et passe bas a permis de mieux cerner cer taines signatures magnetiques et de determiner que les anomalies ovoides prennent source sous la couverture siluro devonienne la plus grande des anomalies ovoides est associee a une anomalie gravimetrique il est propose que ces anomalies geophysiques soient vraisemblablement associees a des roches ultramafiques et ou volcaniques correlatives en profondeur a des lithologies affleurantes des unites cambro ordoviciennes du complexe de lady step et ou du groupe de shickshock

a 40ar 39ar study of oceanic and continental deformation processes during an oblique collision taconian orogeny in the quebec reentrant of the canadian appalachians received 7 december 2006 revised 9 january 2008 accepted 10 march 2008 published 1 july 2008 1 two phases of penetrative deformation are documented in the taconian hinterland of the appalachian orogen in the gaspepeninsula d1 is associated with the obduction of the mont albert ophiolite onto the paleozoic laurentian margin whereas d2 corresponds to later transport of allochthons across the margin in the metamorphic sole s1 is a se dipping mylonitic fabric with a downdip lineation in underlying metabasalts d1 is characterized by nw overturned and recumbent folds and a subhorizontal s1 schistosity with an ene trending orogen parallel lineation d2 is characterized by a s2 steeply dipping penetrative axial planar crenulation cleavage and ne trending f2 folds the intraoceanic thrusting of ophiolite is dated at 465 ma early d1 whereas emplacement of ophiolite andsubsequentdeformationofthemarginwasrecorded by isotopic signatures between 459 and 456 ma late d1 d2 is dated at 448 ma throughout the hinterland taconian transpressive deformation is related to an oblique collision within the quebec reentrant of the canadian appalachians during the ordovician citation malo m g ruffet a pincivy and a tremblay 2008 a 40 ar 39 ar study of oceanic and continental deformation processes during an oblique collision taconian orogeny in the quebec reentrant of the canadian appalachians tectonics 27 tc4001 doi 10 1029 2006tc002094

dendrochronological evidence for a lower water table on peatland around 3200 3000 bc from subfossil pine in northern scotland tree ring analysis of subfossil pinus sylvestris l from nine new peatland sites located beyond the species current northern limit in scotland established a regional chronology called wrath 9 the chronology has been provisionally dated against irish pine chronologies and provides the first annual resolution picture of scots pine expansion from c 3200 bc and subsequent demise from c 3000 bc pine germination and growth is suggested to be associated with a widespread fall in bog water tables that indicates a regional climatic control bog pines progressively declined in number rather than died out in a single event reflecting their growth in a marginal habitat close to a critical ecological threshold the use of tree ring sequences from in situ bog pine macrofossils provides a higher resolution insight into past conditions than possible with existing radiocarbon and pollen based chronologies

the st lawrence platform and appalachian deformation front in the st lawrence estuary and adjacent areas quebec canada structural complexity revealed by magnetic and seismic imaging new magnetic and seismic datasets offer a unique opportunity to document the geometry of the appalachian front in a poorly studied segment of the orogen interpretation of high resolution magnetic data allows for the first time the documentation of the contact between the autochthonous st lawrence platform and the appalachians and highlights the regional significance of previously poorly documented ene faults that experienced post ordovician strike slip motion seismic data reveal tectonic slices in the foreland domain underlying the appalachians and show that the depth of the decollement at the base of the appalachian tectonic wedge varies significantly taken together geological magnetic and seismic data suggest that the geometry of the appalachian front exhibits significant variations in map and cross section views and recorded a polyphased structural history

tectonometamorphic evolution of the southern quebec appalachians 40ar 39ar evidence for middle ordovician crustal thickening and silurian early devonian exhumation of the internal humber zone published age data from the humber zone of the southern quebec appalachians indicate that deformation and metamorphism occurred during middle to late ordovician time this paper presents the results of a regional scale geochronological study of 70 amphibole and mica single grains by the 40 ar 39 ar laser step heating method which brings forward a more complete middle ordovician early devonian tectonometamorphic evolution of the quebec appalachian humber zone biotites have plateau ages varying between 420 and 411 ma amphiboles are often compositionally rimmed and or contain biotite inclusions their age spectra are generally disturbed but may suggest the occurrence of two distinct events silurian 429 424 ma and middle ordovician 462 460 ma two main groups of muscovite ages have been obtained middle ordovician 469 461 ma and silurian early devonian 431 411 ma but middle to late devonian 387 376 ma ages are also locally present middle ordovician ages are interpreted to record crustal thickening by nappe emplacement during regional taconian metamorphism silurian early devonian ages are attributed to consequences of backthrusting and normal faulting a statistical analysis of silurian early devonian muscovite age spectra reveals an irregular decrease in weighted apparent age maxima across the internal humber zone this age decreasing trend is interpreted to result from the temporal ca 431 411 ma and possibly spatial northwest to southeast progression of deformation recrystallization and fluid circulation during tectonic exhumation of the internal humber zone in southern quebec tectonic models for the northern appalachian internal humber zone should take into account the strong body of evidence for silurian early devonian hinterland directed and extensional deformation as documented in southern quebec

silurian extension in the upper connecticut valley united states and the origin of middle paleozoic basins in the quebec embayment pre silurian strata of the bronson hill arch bha in the upper connecticut valley nh vt are host to the latest ludlow comerford intrusive suite consisting east to west of a mafic dike swarm with sheeted dikes and an intrusive complex the rocks are mostly mafic but with compositions ranging from gabbro to leucocratic tonalite the suite is truncated on the west by the monroe fault a late acadian thrust that carries rocks of the bha westward over silurian devonian strata of the connecticut valley gaspetrough cvgt dikes intrude folded strata with a pre intrusion metamorphic fabric taconian but they experienced acadian deforma tion twenty fractions of zircon and baddeleyite from three sample sites of gabbro diorite spanning nearly 40 km yield a weighted 207 pb 206 pb age of 419 1m a greenschist facies dikes sampled over a strike distance of 35 km were tholeiitic basalts formed by partial melting of asthenospheric mantle with little or no influence from mantle or crustal lithosphere the dike chemistry is similar to mid ocean ridge within plate and back arc basin basalts parent magmas originated in the astheno sphere and were erupted through severely thinned lithosphere adjacent to the cvgt extensive middle paleozoic basins in the internides of the appalachian orogen are restricted to the quebec embayment of the laurentian rifted margin and include the cvgt and the central maine trough cmt separated from the bha by a silurian tectonic hinge the ne trending comerford intrusions parallel the cvgt cmt and the tectonic hinge and indicate nw se extension during post taconian convergence the irregular margins of composite laurentia and avalon permitted continued colli sion in newfoundland st lawrence promontory and coeval extension in the quebec embayment extension may be related to hinge retreat of the northwest directed brunswick subduction complex and rise of the asthenosphere following slab break off an alternative hypothesis is that the basins originated as pull apart basins between northwest trending left stepping sinistral strike slip faults along the southern flanks of the new york and st lawrence promontories

cycles and shifts 1 300 years of multi decadal temperature variability in the gulf of alaska the gulf of alaska goa is highly sensi tive to shifts in north pacific climate variability here we present an extended tree ring record of january september goa coastal surface air temperatures using tree ring width data from coniferous trees growing in the mountain ranges along the goa the reconstruction 1514 1999 based on living trees ex plains 44 of the temperature variance although as the number of chronologies decreases back in time this value decreases to and remains around 30 before 1840 verification of the calibrated models is however robust utilizing sub fossil wood we extend the goa reconstruction back to the early eighth century the goa reconstruction correlates significantly 95 cl with both the pacific decadal oscillation index 0 53 and north pacific index 0 42 and therefore likely yields important information on past climate variability in the north pacific region intervention analysis on the goa reconstruction identifies the known twentieth century climate shifts around the 1940s and 1970s al though the mid 1920s shift is only weakly expressed in the context of the full 1 300 years record the well studied 1976 shift is not unique multi taper method spectral analysis shows that the spectral properties of the living and sub fossil data are similar with both records showing significant 95 cl spectral peaks at 9 11 13 14 and 18 19 years singular spectrum analysis identifies in order of importance significant oscillatory modes at 18 7 50 4 38 0 91 8 24 4 15 3 and 14 1 years the amplitude of these modes varies through time it has been suggested minobe in geo phys res lett 26 855 858 1999 that the regime shifts during the twentieth century can be explained by the interaction between pentadecadal 50 4 years and bi decadal 18 7 years oscillatory modes removal of these two modes of variance from our goa time series does indeed remove the twentieth century shifts but many are still identified prior to the twentieth century our analysis suggests that climate variability of the goa is very complex and that much more work is required to understand the underlying oscillatory behavior that is observed in instrumental and proxy records from the north pacific region

persistent positive north atlantic oscillation mode dominated the medieval climate anomaly the medieval climate anomaly mca was the most recent pre industrial era warm interval of european climate yet its driving mechanisms remain uncertain we present here a 947 year long multidecadal north atlantic oscillation nao reconstruction and find a persistent positive nao during the mca supplementary reconstructions based on climate model results and proxy data indicate a clear shift to weaker nao conditions into the little ice age lia globally distributed proxy data suggest that this nao shift is one aspect of a global mca lia climate transition that probably was coupled to prevailing la nina like conditions amplified by an intensified atlantic meridional overturning circulation during the mca

40ar 39ar ages for minerals from the amphibolite dynamothermal aureole mont albert gaspe quebec new 40ar 39ar ages are presented for two hornblendes and one biotite from the dynamothermal aureole that is situated at the base of the mont albeit ophiolite analysis by the incremental release technique reveals a small component of excess 40ar in one hornblende though both exhibit plateau type spectra the biotite was analyzed by the total fusion technique all apparent ages are concordant and average 456 3 ma dynamothermal aureoles form during the obduction process which juxtaposes ophiolites and amphibolite protoliths during a compressional tectonic event at a plate margin in this instance thrusting of the mont albert ophiolite over rocks of the shickshock group the concordance of biotite and hornblende ages indicates rapid postmetamorphic cooling and firmly dates obduction at 456 3 ma ago an age younger than any of the other northern appalachian ophiolites the high pressure metamorphism of the amphibolite is inconsistent with the present high structural level of the composite mont albert

late neoproterozoic to permian tectonic evolution of the quebec appalachians canada abstract due to the unique location of the quebec appalachians in a re entrant of the paleo north american margin and to the fact that the area largely escaped late paleozoic deformation this segment of the orogen preserves evidence of the early orogenic stages that are partly obscured elsewhere despite diachronicity both along and across strike of the orogen five tectonic events of regional significance are recognized 1 the earliest event is mainly recorded by neoproterozoic to early ordovician normal faults associated with extension of the laurentian craton and the establishment of a passive continental margin 2 the second event the ordovician taconian orogeny is marked by foreland directed deformation and corresponds to the principal deformational and metamorphic events recorded by the laurentian margin 3 the third event early salinic is early silurian it is restricted to the southern part of the quebec appalachians and consists of hinterland se directed thrusts folds and retrograde metamorphism 4 the fourth event late salinic is recorded by regional scale late silurian to early devonian normal or transtensional faults and is associated with the formation of the connecticut valley gaspe trough and 5 the last event the devonian acadian orogeny affects with variable intensity all the pre carboniferous lithologies this tectonic synthesis implies that the subdivision of the peri laurentian oceanic tracts proposed in other segments of the appalachians should be applied with caution in quebec and that the structural style the number of oceanic domains and possibly the vergence of subduction change along the strike of the orogen in particular the similarities of the thetford mines and boil mountain ophiolitic complexes and sedimentary covers and the lack of evidence for a major intervening suture are consistent with the maximum allochtony hypothesis i e the assumption that the southern quebec ophiolites are rooted east of the chain lake massif a geodynamic model involving the taconian obduction of a large ophiolitic nappe s the docking of a peri gondwanan gander medial new england terrane in early salinic the formation of large sedimentary basins connecticut valley gaspe and merrimack troughs due to trench rollback and or delamination during the late salinic event and collision at the outer margin of composite laurentia during the acadian orogeny can account for the protracted structural and metamorphic history of the quebec appalachians

high pressure metamorphism in mafic schist from northern vermont the only confirmed occurrence of glaucophane and omphacite in the appalachian mountains of new england is in mafic schist from tillotson peak 44 48 72 33 north central vermont mineral assemblages observed all with epidote sphene magnetite phengitic muscovite carbonate calcite or dolomite apatite sulfide are 1 actinolite glaucophane chlorite garnet quartz 2 actinolite glaucophane chlorite albite garnet 3 actinolite glaucophane omphacite garnet 4 glaucophane chlorite garnet quartz 5 glaucophane omphacite quartz 6 albite glaucophane chlorite quartz and 7 albite paragonite chlorite quartz electron microprobe investigations show that plagioclase chlorite sphene white mica carbonate and magnetite grains are relatively homogeneous however amphibole pyroxene epidote and garnet grains are zoned indicating incomplete equilibration and changing physical conditions during metamorphism glaucophane in assemblage 6 has the general formula rim composition na 1 9 m4 ca 0 1 mg 1 8fe 1 2 2 al 1 0 vi fe 0 3 3 si 7 9 al 0 1 iv o 22 oh 2 glaucophane in assemblages 1 to 5 is somewhat poorer in the glaucophane endmember and richer in actinolite ca rich amphibole grains are zoned extensively with barroisite cores and actinolite rims omphacite grains in assemblages 3 and 5 have the general formula rim composition na 0 5 ca 0 5 mg 0 4 fe 0 1 2 al 0 4 vi fe 0 1 3 si 2o 6 in spite of the significant zoning the partitioning of elements among the minerals at their grain margins suggests that all seven assemblages above may coexist at the same physical conditions of metamorphism in mafic rocks with a relatively small range in bulk composition correlation of mineral compositions and assemblages with mineral stability data suggests high pressure facies series metamorphism at about 9 2 kb and 450 100 c with p h2o p total it is proposed that the metamorphism occurred during the ordovician

conodont biostratigraphy of the codroy group lower carboniferous southwestern newfoundland canada four stratigraphically successive conodont assemblage zones have been recognized in the lower carboniferous codroy group of southwestern newfoundland the diplognathodus zone is confined to the basal ship cove limestone and to a highly fossiliferous correlative at aguathuna the overlying taphrognathus zone occurs in carbonates in the stratigraphic interval above the sequence of massive sulphates and thick clastics the taphrognathus zone as well as the successive cavusgnathus zone has been recognized on fischells brook as well as in the complex section south of codroy the highest conodont zone the gnathodus zone has been recognized in the crabbes jeffreys limestone of the st george s bay area and from south of codroy the discovery of conodonts of the diplognathodus zone in marine strata that are stratigraphie and lithologie correlatives of the macumber and the gays river formations of nova scotia now makes it possible to microfaunally characterize the a subzone a macrofaunal subzone established

40ar 39ar age constraints on taconian and acadian events in the quebec appalachians 40ar 39ar dating of hornblende muscovite and orthoclase from southeastern quebec provides new constraints on the timing grade and regional extent of taconian and acadian metamorphism in the canadian appalachians muscovite ages reveal that the taconic orogeny occurred at ca 463 ma throughout the region lack of reset amphibole indicates that the metamorphic grade did not exceed greenschist facies acadian metamorphism with a peak of 350 c is recorded by an orthoclase cooling age of 377 4 ma this later metamorphism partially reset finer grained muscovite toward the vermont border the calculated 300 340 c closure temperature of orthoclase indicates that this age currently provides the closest estimate of the timing of peak acadian metamorphism north of new england despite the lower grade of taconian and acadian metamorphism in quebec compared to new england peak temperatures appear to have been achieved synchronously in addition investigation of the timing of pre taconic decoupling of the quebec oceanic fragments suggests a protracted obduction history obduction may have displaced slivers of both the subducting and overthrusting oceanic plates

revisiting the appalachian structural front and offshore anticosti basin northern gulf of st lawrence canada by integrating old and new geophysical datasets abstract the anticosti basin is a large predominantly marine sedimentary basin centered within the northern gulf of st lawrence poor quality vintage seismic reflection data collected more than 25 years ago in the offshore part of the basin failed to depict its geometry however recently acquired multibeam bathymetry and magnetic data can be used in combination with high resolution seismic lines to map the paleozoic succession within the honguedo strait the upper part of the offshore sedimentary succession consists of approximately 1140 m of sediments younger than those exposed on anticosti island the offshore part of the basin includes a 40 km wide fold and fault belt sub parallel to the coastline of the gaspe peninsula the structural style is characterized by broad open synclines narrow anticlines and nw striking faults with dextral strike separations which bears similarities to that of the gaspe belt that formed mainly during the middle devonian acadian orogeny this study indicates that the appalachian deformation front is located to the north of its classically inferred location moreover it suggests that the curvature of the early paleozoic assemblages in the gulf of st lawrence is partly a late devonian feature an improved understanding of the offshore architecture of the basin may help to develop new paleogeographic reconstructions and hydrocarbon exploration models in this under explored frontier basin

age and composition of the ruisseau isabelle melange along the shickshock sud fault zone constraints on the timing of melanges formation in the gaspe appalachians melanges are common in the humber and dunnage zones of the quebec appalachians humber zone melanges are spatially associated with taconian nappes and believed to be of tectonic origin dunnage zone melanges are interpreted as relicts of an ordovician accretionary prism the ruisseau isabelle melange rim in the gaspe ap palachians was first interpreted as a dunnage zone melange because of its tectonic position along the baie verte brompton line and lithological components such as dark mudstone blocks of ultramafic rocks and greenish chromite bearing sandstone the rim comprises sedimentary rock assemblages composite shale black shale and chromite bearing sandstone assemblages an exotic block a pebbly mudstone assemblage and slivers of serpentinized peridotite and metamorphic tectonite most melanges of the dunnage zone in the quebec appalachians contain partly similar rocks but their age is not well constrained recent work on the rim and cap chat melange of the humber zone and new fossil finds in the rim rock assemblages allow us to conclude that previous distinction between melanges of the dunnage and humber zones on the basis of rock type associations is not valid according to the age of the rim rock assemblages melanges in the northern gaspe appalachians continued forming after the mid caradocian later than the dunnage zone melanges of southern gaspe appalachians the juxtaposition and structural features of the rim rock assemblages result from repeated faulting along the shickshock sud fault from late ordovi cian to middle devonian

the relative influence of laurentide and local ice sheets during the last glacial maximum in the eastern chic chocs range northern gaspe peninsula quebec geochemical signatures erratic dispersal and striae indicate glacial flows in the north central gaspe peninsula exclusively from appalachian sources except for the coastal fringe during the last glacial maximum lgm ice from the monts mcgerrigle flowed northward and northwestward over the summits of the eastern chic chocs range and the coastal plateau to the gulf of st lawrence lesser flows also occurred to the north from mont albert and the western chic chocs range where intersecting striae were noted the older flows are associated with a locally developed ice cap the rare occurrences of striae and erratics and morphometric and lithological characteristics of summit diamictons imply limited basal erosion by both local and regional ice caps this is postulated to result from early protection of rock surfaces by the initial buildup of thin frozen based ice in the eastern chic chocs range a compact till mantle in the cols and on the coastal plateau and striae parallel to col directions indica

timing of peak metamorphism and deformation along the appalachian margin of laurentia in newfoundland silurian not ordovician u pb and ar ar isotopic age data from the corner brook lake region of the eastern appalachian humber zone in western newfoundland indicate that regional deformation and peak amphibolite facies metamorphism are early silurian a lower limit on deformation is provided by a u pb zircon age of 434 2 3 ma for a pegmatite that is affected by the regional foliation and is interpreted to be syntectonic monazite and rutile from a garnet kyanite staurolite schist which records peak metamorphic conditions and in which porphyroblasts have overgrown the regional foliation gave u pb ages of 430 2 ma and 437 6 ma respectively ar ar cooling ages for hornblende from amphibolites and muscovite from psammitic and pelitic schists range from 430 to 420 ma a silurian age for deformation and metamorphism of the laurentian margin is coincident with the timing of similar events along the newfound land gondwana margin and suggests that the silurian was a period of major continent continent collision

the age and origin of the garnet amphibolite underlying the thetford mines ophiolite quebec the thetford mines ophiolite in southern quebec is partially underlain by an 800 m thick amphibolite aureole rocks in the metamorphic unit grade inward towards the base of the ophiolite from chlorite muscovite schist epidote amphibolite and garnet amphibolite to clinopyroxene bearing garnet amphibolite closest to the fault contact with the basal tectonized peridotite unit of the ophiolite the polydeformed metamorphic unit pinches out north and south of belmina ridge and is discordant with the overlying tectonized peridotite analyses of nine samples show a range of compositions but the low k2o p2o5 rb zr and sr suggest that the amphibolite protolith was tholeiitic basalt probably midocean ridge tholeiite microprobe mineral compositions determined for coexisting clinopyroxene garnet amphibole and garnet amphibole suggest that amphibolites near the peridotite contact equilibrated at about 850 c and that the temperatures decreased to about 380 c 700 m from the contact geobarometers based on coex

tectonism and exhumation in convergent margin orogens insights from ore deposits abstract three widespread and abundant types of ore deposits epithermal silver gold ag au porphyry copper cu and orogenic gold au form by hydrothermal activity during tectonic convergence along continental margins and their preservation provides new insights into rates of those processes that form and destroy ore deposits as well as overlying rock ages for each of the three deposit types define lognormal age frequency distributions that are nearly identical in form but differ in their modal ages epithermal ag au porphyry cu and orogenic au deposits exhibit age modes at 3 11 and 199 ma respectively these ore types form at depths of 0 5 1 9 and 10 km respectively such that modal age increases with depth of ore emplacement qualitatively the dearth of deposits younger than their modal age reflects the fact that ore deposits form at depth within the crust and time is required for exhumation to expose them continued erosion serves to destroy ore bodies giving rise to fewer deposits

tornetrask tree ring width and density ad 500 2004 a test of climatic sensitivity and a new 1500 year reconstruction of north fennoscandian summers this paper presents updated tree ring width trw and maximum density mxd from tornetrask in northern sweden now covering the period ad 500 2004 by including data from relatively young trees for the most recent period a previously noted decline in recent mxd is eliminated non climatological growth trends in the data are removed using regional curve standardization rcs thus producing trw and mxd chronologies with preserved low frequency variability the chronologies are calibrated using local and regional instrumental climate records a bootstrapped response function analysis using regional climate data shows that tree growth is forced by april august temperatures and that the regression weights for mxd are much stronger than for trw the robustness of the reconstruction equation is verified by independent temperature data and shows that 63 64 of the instrumental inter annual variation is captured by the tree ring data this is a significant improvement compared to previously published reconstructions based on tree ring data from tornetrask a divergence phenomenon around ad 1800 expressed as an increase in trw that is not paralleled by temperature and mxd is most likely an effect of major changes in the density of the pine population at this northern tree line site the bias introduced by this trw phenomenon is assessed by producing a summer temperature reconstruction based on mxd exclusively the new data show generally higher temperature estimates than previous reconstructions based on tornetrask tree ring data the late twentieth century however is not exceptionally warm in the new record on decadal to centennial timescales periods around ad 750 1000 1400 and 1750 were equally warm or warmer the 200 year long warm period centered on ad 1000 was significantly warmer than the late twentieth century p 0 05 and is supported by other local and regional paleoclimate data the new tree ring evidence from tornetrask suggests that this medieval warm period in northern fennoscandia was much warmer than previously recognized

gaspe belt subsurface geometry in the northern quebec appalachians as revealed by an integrated geophysical and geological study 1 potential field mapping abstract together recent gravity and high resolution aeromagnetic datasets are used to qualitatively investigate the upper and middle crustal geometry of the middle paleozoic gaspe belt in the northern appalachians long wavelength potential field anomalies define two sub basins that are divided by northeast trending gravity highs for each sub basins gravity lows correlate with the youngest rock units maps that highlight anomalies associated with near surface features at the expense of those related to deeper sources provide an important supplement to the spatially discrete observations derived from bedrock mapping analysis of such maps indicates that the sub basins are characterized by different structural patterns and that faults trending obliquely compared to the main structural grain have been previously underestimated the geometry of the gaspe belt as revealed by this integrated geophysical and geological study bears similarities with orogens exhibiting lateral extrusion this geometry is interpreted as the result of a heterogeneous strain regime in front of an indenter corresponding to the early paleozoic gander dunnage crustal block the indentation tectonic model is supported by 1 the various strike and kinematic of faults that suggest a strongly heterogeneous strain regime 2 the greater geological complexity and the occurrence of faults with a significant thrust component in front of the indenter 3 the predominance of dextral strike slip faults in the eastern gaspe peninsula that result in lateral material transport away from the indenter 4 the location of abundant devonian magmatic dykes sills and stocks in a fault bounded zone that experienced local extension 5 the occurrence of block rotation

palynostratigraphy and lithostratigraphy of carboniferous upper codroy group and barachois group southwestern newfoundland a new zone the reticulatisporites carnosus assemblage zone of late pendleian to arnsbergian age is proposed for miospore assemblages in the searston formation of the barachois group and in unnamed coal bearing strata in higher portions of the group the beds containing the zone can be correlated with those in other parts of the euramerican floral province in western europe including the north sea where the climate was semi humid temporal relationships suggested by these new biostratigraphic data indicate that a reassessment of the regional lithostratigraphy of southwestern newfoundland is required the overfall brook member of the robinsons river formation formerly assigned with its correlative the brow pond lentil to the codroy group is here identified as a basal unit of the searston formation it lies unconformably on codroy group beds of brigantian age elsewhere the basal beds of the barachois group lie unconformably on pre carboniferous rocks the barachois group in the codroy and st george s bay lowlands correlates with the humber falls and howley formations of the deer lake subbasin of western newfoundland and with the pomquet formation of the mabou group nova scotia the pendleian arnsbergian coal bearing strata high in the undivided barachois group predate the post arnsbergian major floral crisis and with their correlatives represent the youngest known rock units of mississippian age in atlantic canada they are significantly older than the pennsylvanian coal measures of moscovian bolsovian age in a small outlier near stephenville and we recommend the latter be removed from the barachois group

regional metamorphism of the appalachian humber zone of gaspe peninsula 40ar 39ar evidence for crustal thickening during the taconian orogeny geochronological studies on the timing of deformation and metamorphism along the laurentian margin have shown that the ages of metamorphic events change along strike within the newfoundland southern quebec segment of the canadian appalachians the gaspe peninsula is located at mid point of the two extremities of this segment new single grain laser 40ar 39ar plateau ages solely reflect latest middle late ordovician metamorphism samples taken within the internal humber zone in the shickshock group rocks yield 40ar 39ar muscovite and hornblende ages ranging from 457 to 454 ma samples from the amphibolite du diable the metamorphic sole of the mont albert ophiolite yield 40ar 39ar muscovite and hornblende ages ranging from 459 to 457 ma ordovician ages of the internal humber zone are consistent with 40ar 39ar ages from southern quebec and are interpreted as the result of the emplacement onto the margin of both the ophiolite and its metamorphic sole

reconstructing holocene climate from tree rings the potential for a long chronology from the scottish highlands despite promising research in the 1980s showing the potential of scots pine pinus sylvestris l for the reconstruction of past summer temperatures in the scottish highlands little dendroclimatic work has been attempted in this region since this reflects in part the limited number of sparsely distributed remnant natural semi natural pine woodlands in the scottish highlands and the lack of old growth forest therein on average most of the pine trees dated in this region are around 225 years in age here we present the first results of an ongoing interdisciplinary initiative to develop a long scottish chronology through the acquisition of modern historical and subfossil pine material from the native pinewoods historic structures and lakes of the scottish highlands radiocarbon dating of 25 subfossil pine timbers recovered from lake sediments identified the presence of preserved material covering the last 8000 years with initial clusters focused on the last two millennia and early mid holocene alth

reconstructing 800 years of summer temperatures in scotland from tree rings this study presents a summer temperature reconstruction using scots pine tree ring chronologies for scotland allowing the placement of current regional temperature changes in a longer term context living tree chronologies were extended using subfossil samples extracted from nearshore lake sediments resulting in a composite chronology 800 years in length the north cairngorms ncairn reconstruction was developed from a set of composite blue intensity high pass and ring width low pass filtered chronologies with a range of detrending and disturbance correction procedures calibration against july august mean temperature explains 56 4 of the instrumental data variance over 1866 2009 and is well verified spatial correlations reveal strong coherence with temperatures over the british isles parts of western europe southern scandinavia and northern parts of the iberian peninsula ncairn suggests that the recent summer time warming in scotland is likely not unique when compared to multi decadal warm periods observed in the 1300s 1500s and 1730s although trends before the mid sixteenth century should be interpreted with some caution due to greater uncertainty prominent cold periods were identified from the sixteenth century until the early 1800s agreeing with the so called little ice age observed in other tree ring reconstructions from europe with the 1690s identified as the coldest decade in the record the reconstruction shows a significant cooling response 1 year following volcanic eruptions although this result is sensitive to the datasets used to identify such events in fact the extreme cold and warm years observed in ncairn appear more related to internal forcing of the summer north atlantic oscillation

paleogeography of the matapedia basin in the gaspe appalachians initiation of the gaspe belt successor basin the matapedia basin consists of the uppermost ordovician lowermost silurian deep water fine grained carbonate siliciclastic rocks of the honorat garin formation and matapedia groups pabos and white head formations the lower rock assemblage of the gaspe belt in the gaspe appalachians paleogeographic maps of eight time slices from the caradocian to the llandoverian are presented to better understand the tectonosedimentary evolution of the matapedia basin deposition evolved from siliciclastic garin fm to argillaceous limestones pabos fm to limestones white head fm the overall change from terrigenous garin fm to limestone facies white head fm reflects a change in the source area paleocurrent directions and composition of sandstones indicate an orogenic source area to the south for the garin formation which is believed to be the inliers of the humber and dunnage zones in the southern gaspe and new brunswick appalachians lime muds deposited by turbidity currents coming from the nor

a well verified multiproxy reconstruction of the winter north atlantic oscillation index since a d 1400 abstract a new well verified multiproxy reconstruction of the winter north atlantic oscillation nao index is described that can be used to examine the variability of the nao prior to twentieth century greenhouse forcing it covers the period a d 1400 1979 and successfully verifies against independent estimates of the winter nao index from european instrumental and noninstrumental data as far back as 1500 the best validation occurs at interannual timescales and the weakest at multidecadal periods this result is a significant improvement over previous proxy based estimates which often failed to verify prior to 1850 and is related to the use of an extended reconstruction model calibration period that reduced an apparent bias in selected proxies associated with the impact of anomalous twentieth century winter nao variability on climate teleconnections over north atlantic sector land areas although twentieth century nao variability is somewhat unusual comparable periods of persistent positive phase

development of inverted metamorphic gradient in the internal domain of the taconian belt gaspe peninsula the mont logan nappe is part of the taconian internal domain of the quebec appalachians and is entirely made up of synrift to passive margin elastics and volcanics of the shickshock group rocks o

a reevaluation of the position of the baie verte brompton line in the quebec appalachians the influence of middle devonian strike slip faulting in gaspe peninsula the baie verte brompton line bbl the surface expression of the taconian suture in the canadian appalachian orogen extends from southern quebec to the northeast end of newfoundland in the que

hinterland directed transtensional faulting at an orogen structural front the example of the cap chat melange quebec appalachians the cap chat melange is a regional scale dismembered unit that occurs close to the quebec appalachian front the melange records early d 1 taconian and late d 3 acadian regional deformations the greater degree of disruption of the melange compared with surrounding units is due to the superimposition of d 2 structures that are rare outside the melange d 2 structures include both layer extensional features such as block disruption along shear zones and faults and layer contractional features such as folds that record the transtensional collapse of the taconian orogenic wedge along a rheologically weak deformation zone the cap chat melange is interpreted as the westernmost remnant of a zone of mechanical decoupling in the upper crust which allows normal or transtensional faulting in the inner parts of the orogen this paper presents evidence that beyond the general complexity of melange units geological observations may still contribute to unraveling their tectonic history and that transtensional reactivation of original thrust faults is a viable mechanism in the frontal parts of orogens

the palaeobiogeographic significance of lower carboniferous crustaceans ostracodes and peracarids from western newfoundland and central nova scotia canada abstract lower carboniferous sediments of the maritime basin of eastern canada were deposited in a predominantly fluvial environment subjected to transgressive marine episodes a dominantly shallow marine peracarid and ostracode fauna the latter consisting mostly of paraparchitaceans palaeocopids and bairdiaceans has been recovered from sediments in the area the maritime basin is considered to have been a tectonically active epicontinental extension of the northern hercynian ocean its lower carboniferous crustacean fauna shows a strong affinity to contemporaneous western european and russian faunas the high degree of similarity exhibited by these faunas and also the lack of similarity to contemporaneous north american and north african faunas are explained in terms of a circulation model for the hercynian ocean and adjacent areas the circulation model is based upon the application of the physical principles that define the behaviour of oceanic surface waters to a palaeogeographic reconstruction of the visean northern hercynian ocean and surrounding regions

historical storminess and climate see saws in the north atlantic region the existence of a well defined climate see saw across the north atlantic region and surrounding areas has been known for over 200 years the occurrence of severe winters in western greenland frequently coincides with mild winters in northern europe conversely mild winters in western greenland are frequently associated with cold winters across northern europe whereas this see saw is normally discussed in terms of air temperature and pressure differences here we explore how the climate see saw is reflected in records of historic storminess from scotland nw ireland and iceland it is concluded that the stormiest winters in these regions during the last ca 150 years have occurred when western greenland temperatures have been significantly below average in contrast winters of reduced storminess have coincided with winters when air temperatures have been significantly above average in western greenland this reconstruction of winter storminess implies a relationship between chronologies of coastal erosion and the history of north atlantic climate see saw dynamics with sustained winter storminess and hence increased coastal erosion taking place when the icelandic low pressure cell is strongly anchored within the circulation of the northern hemisphere considered over the last ca 2000 years it would appear that winter storminess and climate driven coastal erosion was at a minimum during the medieval warm period by contrast the time interval from ca ad 1420 until present has been associated with sustained winter storminess across the north atlantic that has resulted in accelerated coastal erosion and sand drift d 2004 elsevier b v all rights reserved

summer temperatures in the canadian rockies during the last millennium a revised record we present a significant update to a millennial summer temperature reconstruction 1073 1983 that was originally published in 1997 utilising new tree ring data predominantly picea engelmannii the reconstruction is not only better replicated but has been extended 950 1994 and is now more regionally representative calibration and verification statistics were improved with the new model explaining 53 of may august maximum temperature variation compared to the original 39 of april august mean temperatures the maximum latewood density data which are weighted more strongly in the regression model than ringwidth were processed using regional curve standardisation to capture potential centennial to millennial scale variability the reconstruction shows warm intervals comparable to twentieth century values for the first half of the eleventh century the late 1300s and early 1400s the bulk of the record however is below the 1901 1980 normals with prolonged cool periods from 1200 to 1350 and from 1450 to the late 19th century the most extreme cool period is observed to be in the 1690s these reconstructed cool periods compare well with known regional records of glacier advances between 1150 and the 1300s possibly in the early 1500s early 1700s and 1800s evidence is also presented of the influence of solar activity and volcanic events on summer temperature in the canadian rockies over the last 1 000 years although this reconstruction is regional in scope it compares well at multi decadal to centennial scales with northern hemisphere temperature proxies and at millennial scales with reconstructions that were also processed to capture longer timescale variability this coherence suggests that this series is globally important for the assessment of natural temperature variability over the last 1 000 years

hortonella uttingii gen nov sp nov udoteacees algues vertes du carbonifere inferieur we describe here a new algal taxon observed in tournaisian rocks of the horton group nova scotia the thallus morphology suggests an udoteacean but the central medullary tubes are divided by septiform processes a character normally associated with the rhodophyta hortonella is also recognized in visean strata of nova scotia newfoundland alberta and algeria

ordovician and silurian metamorphic cooling ages along the laurentian margin of the quebec appalachians bridging the gap between new england and newfoundland geochronological studies on the timing of deformation and metamorphism along the laurentian margin have shown that the ages of metamorphism events change along the strike of the newfoundland new england segment of the appalachian orogen the quebec appalachians represent a critical transition zone where new single grain laser 40 ar 39 ar plateau ages show that both middle ordovician and silurian deformation and metamorphism are recorded parts of the analyzed samples give 40 ar 39 ar muscovite ages ranging from 468 to 461 ma these samples were taken within structural windows of the eastern internal humber zone that are overlain by ophiolitic and melange rocks of the dunnage zone other analyzed samples yielded silurian 40 ar 39 ar muscovite ages clustering from 425 to 421 ma these samples were taken across the notre dame mountains anticlinorium which represents a structural and metamorphic dome within the internal humber zone the middle ordovician ages of southern quebec are coeval with data from western new england and are interpreted as representing cooling shortly after the peak taconian regional metamorphism the silurian ages which have never been previously documented in the quebec appalachians are comparable to those described in newfoundland however they are not attributed to tectonism that shows characteristics of an orogen scale continent continent collision salinian orogeny but rather those of late taconian backthrusting and normal faulting or a period of crustal extension that followed the main taconian crustal thickening

temperature sensitive tien shan tree ring chronologies show multi centennial growth trends two millennia length juniper ring width chronologies processed to preserve multi centennial growth trends are presented for the alai range of the western tien shan in kirghizia the chronologies average the information from seven near timberline sampling sites and likely reflect summer temperature variation for comparison chronologies are also built using standard dendrochronological techniques we briefly discuss some qualities of these inter decadal records and show the low frequency components removed by the standardization process include a long term negative trend in the first half of the last millennium and a long term positive trend since about ad 1800 the multi centennial scale alai range chronologies where these trends are retained are both systematically biased but in an opposite sense in their low frequency domains nevertheless they represent the best constraints and estimates of long term summer temperature variation and reflect the medieval warm period the little ice age and a period of warming since about the middle of the nineteenth century

acadian metamorphism in the dunnage zone of southern quebec northern appalachians 40ar 39ar evidence for collision diachronism in new england the acadian orogen is divided into western and eastern metamorphic belts on the basis of contrasting pressure temperature p t paths peak metamorphism conditions and ages along strike correlations of structures indicate that rock units affected by devonian metamorphism and deformation in southern quebec belong to the western acadian belt and share the same tectonic evolution as in new england muscovite 40 ar 39 ar ages obtained from greenschist grade ordovician volcanic and plutonic rocks of the ascot complex in southern quebec indicate that acadian metamorphism and deformation peaked ca 380 375 ma ordovician muscovite ages of ca 462 ma are locally well preserved in the granitic intrusion of the ascot complex and provide constraints on the timing of island arc plutonism in the dunnage zone of southern quebec ordovician 40 ar 39 ar age spectra do not show important losses of radiogenic argon indicating that acadian metamorphism has been low grade with temperatures below the ar isotopic closure temperature proposed for muscovite acadian peak metamorphism is significantly younger and p t conditions of regional deformation have been lower in southern quebec than in amphibolite grade rocks of the western acadian belt of new england in the northern appalachians acadian metamorphism and deformation are attributed to devonian age crustal overthickening related to plate convergence the comparison of devonian tectonic fabrics in new england and southern quebec suggests that progression in the timing and p t conditions of acadian peak metamorphism in both areas are the result of the irregular geometry of the collision zone and of the northward migration of metamorphic and structural fronts along the orogen

volcanic cooling signal in tree ring temperature records for the past millennium the authors acknowledge the national science foundation for funding much of the research presented herein rw s scottish work is currently funded through the uk leverhulme trust and natural environment research council nerc projects relic reconstructing 8000 years of environmental and landscape change in the cairngorms f 00 268 bg and scot2k reconstructing 2000 years of scottish climate from tree rings ne k003097 1

the arctic oscillation signature in the wintertime geopotential height and temperature fields the leading empirical orthogonal function of the wintertime sea level pressure field is more strongly coupled to surface air temperature fluctuations over the eurasian continent than the north atlantic oscillation nao it resembles the nao in many respects but its primary center of action covers more of the arctic giving it a more zonally symmetric appearance coupled to strong fluctuations at the 50 hpa level on the intraseasonal interannual and interdecadal time scales this arctic oscillation ao can be interpreted as the surface signature of modulations in the strength of the polar vortex aloft it is proposed that the zonally asymmetric surface air temperature and mid tropospheric circulation anomalies observed in association with the ao may be secondary baroclinic features induced by the land sea contrasts the same modal structure is mirrored in the pronounced trends in winter and springtime surface air temperature sea level pressure and 50 hpa height over the past 30 years parts of eurasia have warmed by as much as several k sea level pressure over parts of the arctic has fallen by 4 hpa and the core of the lower stratospheric polar vortex has cooled by several k these trends can be interpreted as the development of a systematic bias in one of the atmosphere s dominant naturally occurring modes of variability

a 1052 year tree ring proxy for alpine summer temperatures a june august alpine temperature proxy series is developed back to ad 951 using 1 527 ring width measurements from living trees and relict wood the reconstruction is composed of larch data from four alpine valleys in switzerland and pine data from the western austrian alps these regions are situated in high elevation alpine environments where a spatially homogenous summer temperature signal exists in an attempt to capture the full frequency range of summer temperatures over the past millennium from inter annual to multi centennial scales the regional curve standardization technique is applied to the ring width measurements correlations of 0 65 and 0 86 after decadal smoothing with high elevation meteorological stations since 1864 indicate an optimal response of the rcs chronology to june august mean temperatures the proxy record reveals warm conditions from before ad 1000 into the thirteenth century followed by a prolonged cool period reaching minimum values in the 1820s and a warming trend into the twentieth century this latter trend and the higher frequency variations compare well with the actual high elevation temperature record the new central alpine proxy suggests that summer temperatures during the last decade are unprecedented over the past millennium it also reveals significant similarities at inter decadal to multi centennial frequencies with large scale temperature reconstructions however deviating during certain periods from h h lamb s european north atlantic temperature history

summer temperature variations in the european alps a d 755 2004 abstract annually resolved summer temperatures for the european alps are described the reconstruction covers the a d 755 2004 period and is based on 180 recent and historic larch larix decidua mill density series the regional curve standardization method was applied to preserve interannual to multicentennial variations in this high elevation proxy dataset instrumental measurements from high low elevation grid boxes back to 1818 1760 reveal strongest growth response to current year june september mean temperatures the reconstruction correlates at 0 7 with high elevation temperatures back to 1818 with a greater signal in the higher frequency domain r 0 8 low elevation instrumental data back to 1760 agree with the reconstruction s interannual variation although a decoupling between warmer instrumental and cooler proxy data before 1840 is noted this offset is larger than during any period of overlap with more recent high elevation instrumental data even though the proxy time series

taconian and acadian transpression between the internal humber zone and the gaspe belt in the gaspe peninsula tectonic history of the shickshock sud fault zone the shickshock sud fault has a history of ordovician taconian silurian salinic and devonian acadian movements taconian deformation involving ductile dextral oblique slip faulting is recorded in cambrian rocks in the footwall of the shickshock sud fault metabasalt and metaarkose at amphibolite grade are converted into phyllonite and mylonitic schist shear bands asymmetric garnet porphyroclasts c s fabrics and mica fish textures indicate dextral shearing the regional sense of shear is top to west and southwest on generally southeast dipping shear zones hornblende of metabasalt yielded an 40ar 39ar age of 455 9 2 ma and muscovite from the mylonitic schist yielded an 40ar 39ar age of 454 3 0 9 ma which indicate metamorphism and deformation during the taconian orogeny evidence for silurian activity is indicated by the salinic unconformity to the south related to normal block faulting deformation features in the ordovician and silurian devonian rocks in the hanging wall were predominantl

late holocene pinewoods persistence in the gredos mountains central spain inferred from extensive megafossil evidence macro and megafossil studies are of great value in palaeoecology because such evidence is spatially precise directly radiocarbon dated and usually taxon specific here we present new macro and megafossil data from ten sites from the gredos mountains central iberian peninsula that suggest persistent forest cover through the late holocene with a widespread belt of pinewoods in the highlands of the central iberian mountains well preserved pine cones found at several sites revealed that both pinus sylvestris and pinus nigra were present in the area during the middle and late holocene at locations of important biogeographical interest the p sylvestris forests represent one of the southernmost locations of its entire range p nigra was not known to have occurred in central spain during the holocene it was found at the westernmost edge of its range in siliceous soils a rare environment compared with the rest of its distribution finally we explored the potential for obtaining a long pine chronology from central iberia using tree ring measurements and radiocarbon dating of pine subfossil logs

along strike acadian structural variations in the quebec appalachians consequence of a collision along an irregular margin the quebec appalachians have been shaped by two major orogenies the middle to late ordovician taconian and the middle devonian acadian thrust faults and nappe structures characterized the taconian deformation throughout the quebec appalachians whereas structural styles pertaining to the acadian orogeny differ from southern quebec to the gaspe peninsula structural analysis of late ordovician to middle devonian supracrustal rocks shows two different acadian deformational regimes strike slip tectonics in the gaspe peninsula and thrust or dip slip tectonics in southern quebec in southern quebec acadian regional deformation produced folds which vary from upright to overturned and tight to isoclinal from the nw to the se major faults e g la guadeloupe are northwestward directed thrust faults marked by highly ductile shear zones outlined by mylonite in the gaspe peninsula structural trend is ne and major e w dextral strike slip faults transect this trend folds are open and upright inclined and tighter near the major faults where they have a clockwise rotation like the regional cleavage major faults e g grand pabos follow corridors delimiting high strain zones where the fabrics developed are indicative of a ductilebrittle regime of deformation in the temiscouata region major structural features of both southern quebec and the gaspe peninsula are recognized structures of this region consist of ene trending dextral strike slip faults and high angle wnw verging reverse faults parallel to major nne folds these structures reflect the transition from purely horizontal movement along major strike slip faults of the gaspe peninsula to vertical movement along thrust faults in southern quebec acadian structural variations within the quebec appalachians are interpreted in terms of a continental collision of gondwana along the irregular margin of laurentian and its taconian accreted terranes

the late holocene kauri chronology assessing the potential of a 4500 year record for palaeoclimate reconstruction abstract millennial and multi millennial tree ring chronologies can provide useful proxy records of past climate giving insight into a more complete range of natural climate variability prior to the 20th century since the 1980s a multi millennial tree ring chronology has been developed from kauri agathis australis from the upper north island new zealand previous work has demonstrated the sensitivity of kauri to the el nino southern oscillation enso here we present recent additions and extensions to the late holocene kauri chronology lhkc and assess the potential of a composite master chronology agauc13 for palaeoclimate reconstruction the updated composite kauri chronology now spans 4491 years 2488 bce 2002 ce and includes data from 18 modern sites 25 archaeological sites and 18 sub fossil swamp kauri sites consideration of the composition and statistical quality of agauc13 suggests the lhkc has utility for palaeoclimate reconstruction but there are caveats these include a differences in character between the three assemblages including growth rate and sensitivity b low sample depth and low statistical quality in the 10th 13th century ce when the record transitions from modern and archaeological material to the swamp kauri c a potential difference in amplitude of the signal in the swamp kauri d a westerly bias in site distribution prior to 911 ce e variable statistical quality across the entire record associated with variable replication and f complex changes in sample depth and tree age and size which may influence centennial scale trends in the data further tree ring data are required to improve statistical quality particularly in the first half of the second millennium ce

a 7500 year peat based palaeoclimatic reconstruction and evidence for an 1100 year cyclicity in bog surface wetness from temple hill moss pentland hills southeast scotland analyses of plant macrofossils peat humification and testate amoebae were used to reconstruct a proxy climate record spanning the last 7500 years from an ombrotrophic bog temple hill moss in southeast scotland the plant macrofossil data were subjected to detrended correspondence analysis dca which modelled effectively the significant wet shifts within the record a mean water table depth transfer function was applied to the testate amoebae data to provide quantifiable changes the three proxy records show coherent phase changes which are interpreted as variability in past effective precipitation two tephra horizons glen garry and lairg a were used in conjunction with radiocarbon dates to construct an age depth model producing a robust geochronology from which a time series was calculated the palaeoclimatic reconstruction identified major wet shifts throughout the holocene with specific events occurring around cal 6650 5850 5300 4500 3850 3400 2800 2450 1450 1350 and 250 150 bp spectral analysis of the plant macrofossil dca and colorimetric humification data produced a millennial scale periodicity of 1100 years the same periodicity has also been found in a palaeoclimatic reconstruction from a site in cumbria walton moss and may be linked with millennial scale periodicities found in oceanic palaeoclimatic records

ophiolite obduction in the quebec appalachians canada 40 ar 39 ar age constraints and evidence for syn tectonic erosion and sedimentation 1 2 3 detailed field work conducted in the dunnage zone of the quebec appalachians is herein combined with 40 ar 39 ar dating on a series of ophiolitic massifs crosscutting granites and associated metamorphic rocks occurring along the baie verte brompton line the taconian suture between laurentia and lower paleozoic peri laurentian oceanic terranes studied massifs are the lac brompton ophiolite and the riviere des plante ultramafic complex in southern quebec and the nadeau ophiolitic melange in the gaspe peninsula our work suggests that these massifs form remnants of eroded ophiolitic nappes which are unconformably overlain by the saint daniel and riviere port daniel melanges and correlate with the thetford mines and mont albert ophiolitic complexes our 40 ar 39 ar data and compiled regional age constraints indicate that ophiolite obduction was diachronous along the strike of the orogen the timing of obduction and melange formation varies according to the irregular geometry of the early paleozoic laurentian margin with earlier collision occurring along or at the margins of promontories obduction was initiated with the formation of infraophio litic metamorphic soles between ca 479 and 472 ma in southern quebec and the nadeau ophiolitic melange and pos sibly as late as ca 470 466 ma for the mont albert complex these sole rocks were later exhumed and translated onto the laurentian margin with the overlying ophiolites between 475 and 460 457 ma the uplifting and erosion of the orogenic wedge during the waning stages of obduction has resulted in the sedimentation of olistostromal melanges and onlapping flysch units above the ophiolitic nappes as well as foredeep flysch successions during the latest arenig to earliest caradoc