sm nd isotopic investigation of the age and origin of the meguma zone metasedimentary rocks the meguma zone of southern nova scotia is a suspect terrane in the eastern appalachians sm nd isotopic data on six samples from the thick sequence of flyschoid metasediments of the meguma group show that these rocks have a mean crustal residence age of tdm 1773 95 ma considerably older than their cambro ordovician depositional age this information should be useful in locating the matching terrane for the meguma and ultimately in determining whether it was derived from one or more precambrian sources with different crustal residence times

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

chemical and isotopic pb sr zonation in a peraluminous granite pluton role of fluid fractionation the davis lake pluton dlp 800 km2 of southwestern nova scotia canada part of the large peraluminous south mountain batholith of ca 380 ma u pb zircon ar ar mica consists of granite and subordinate topaz muscovite leucogranite that hosts greisen tin base metal mineralization a new pb pb isochron age for leucogranite from the most evolved part of the dlp indicates a crystallization age of 378 3 6 ma coincident with other radiometric ages of the dlp rb sr re os pb pb the intrusion displays a compositional zonation defined by lead and strontium isotopic ratios as well as some major elements e g si f incompatible trace elements e g li rb ta u sn and elemental ratios e g k rb and nb ta the greisens and the leucogranites that host them are characterized by extreme radiogenic compositions for pb and sr and their chemical isotopic trends are extensions of the trends displayed by the less evolved granites the covariations of the isotopic ratios with several major and trace elements and elemental ratios as well as the pb pb and rb sr isochrones indicate that all phases of the intrusion originated from a homogeneous parental magma the granitoid magma underwent extensive fractional crystallization of feldspars minor biotite and accessory minerals monazite apatite and zircon in a compositionally zoned magma chamber that was subsequently accompanied by fluid fractionation during which time the internally derived fluorine rich fluids modified the rb sr u pb and th pb ratios leading to distinct variations of 87sr 86sr 206pb 204pb 238u 204pb and 232th 204pb isotopic ratios these data therefore document the evolution of a granitic magma through magmatic i e crystal fractionation orthomagmatic i e crystal fluid fractionation and hydrothermal i e fluid fractionation stages that culminated in the formation of a tin base metal deposit the pb isotope data also constrain the source region for the dlp as being avalonian basement that by inference must underlie much of the meguma terrane

new u pb zircon ages and the duration and division of devonian time newly determined u pb zircon ages of volcanic ashes closely tied to biostratigraphic zones are used to revise the devonian time scale they are 1 417 6 1 0 ma for an ash within the conodont zone of icriodus woschmidti i w hesperius early lochkovian 2 408 3 1 9 ma for an ash of early emsian age correlated with the conodont zones of po dehiscens lower po inversus 3 391 4 1 8 ma for an ash within the po c costatus zone and probably within the upper half of the zone eifelian and 4 381 1 1 3 ma for an ash within the range of the frasnian conodont palmatolepis punctata pa punctata zone to upper pa hassi zone u pb zircon ages for two rhyolites bracketing a palyniferous bed of the pusillites lepidophyta spore zone are dated at 363 8 2 2 ma and 363 4 1 8 ma respectively suggesting an age of363 ma for a level within the late famennian pa g expansa zone these data together with other published zircon ages suggest that the base and top of the devonian lie close to 418 ma and 362 ma respectively thus lengthening the period by20 over current estimates we suggest that the duration of the middle devonian eifelian and givetian is rather brief perhaps no longer than 11 5 myr 394 ma 382 5 ma and that the emsian and famennian are the longest stages in the period with estimated durations of15 5 myr and 14 5 myr respectively 1998 elsevier science b v all rights reserved

40ar 39ar dating of micas from the east kemptville tin deposit yarmouth county nova scotia the east kemptville tin deposit in nova scotia the largest known tin deposit in north america lies in a greisen zone within the davis lake pluton generally considered to be part of the devonian south mountain batholith our dating of micas from within the deposit suggests that the greisenization process that accompanied mineralization took place about 295 5 ma ago that is ca 60 ma after the emplacement of the batholith hydrothermal alteration mineralization activity in southern nova scotia coincided with extensive shearing and tectonism throughout the hercynian orogen the east kemptville deposit appears to be approximately coeval with similar mineralization in southwest england the iberian peninsula and northwest africa and much younger than the devonian acadian orogeny

the deep ocean during the last interglacial period oxygen isotope analysis of benthic foraminifera in deep sea cores from the atlantic and southern oceans shows that during the last interglacial period north atlantic deep water nadw was 0 4 0 2 c warmer than today whereas antarctic bottom water temperatures were unchanged model simulations show that this distribution of deep water temperatures can be explained as a response of the ocean to forcing by high latitude insolation the warming of nadw was transferred to the circumpolar deep water providing additional heat around antarctica which may have been responsible for partial melting of the west antarctic ice sheet

ice complex permafrost of mis5 age in the dmitry laptev strait coastal region east siberian arctic ice complex deposits locally known as the buchchagy ice complex are exposed at both coasts of the east siberian dmitry laptev strait and preserved below the yedoma ice complex that formed during mis3 and mis2 marine isotope stage and lateglacial holocene thermokarst deposits mis1 radioisotope disequilibria 230th u of peaty horizons date the buchchagy ice complex deposition to 126 16 13 kyr and 117 19 14 kyr until 98 5 kyr and 89 5 kyr the deposit is characterised by poorlysorted medium to coarse silts with cryogenic structures of horizontal ice bands lens like and lenslike reticulated segregation ice two peaty horizons within the buchchagy ice complex and syngenetic ice wedges 2e4 m wide up to 10 m high are striking the isotopic composition d18o dd of buchchagy ice wedge ice indicates winter conditions colder than during the mis3 interstadial and warmer than during mis2 stadial and similar atmospheric winter moisture sources as during the mis2 stadial buchchagy ice complex pollen spectra reveal tundra steppe vegetation and harsher summer conditions than during the mis3 interstadial and rather similar vegetation as during the mis2 stadial short term climatic variability during mis5 is reflected in the record even though the regional chronostratigraphic relationship of the buchchagy ice complex to the last interglacial remains unclear because numerical dating is widely lacking the present study indicates permafrost ice complex formation during mis5 sensu lato and its preservation afterwards palaeoenvironmental insights into past climate and the periglacial landscape dynamics of arctic lowlands in eastern siberia are deduced from the record

instability of climate and vegetation dynamics in central and eastern europe during the final stage of the last interglacial eemian mikulino and early glaciation abstract in terrestrial records from central and eastern europe the end of the last interglacial seems to be characterized by evident climatic and environmental instabilities recorded by geochemical and vegetation indicators the transition mis 5e 5d from the last interglacial eemian mikulino to the early last glacial early weichselian early valdai is marked by at least two warming events as observed in geochemical data on the lake sediment profiles of central grobern neumark nord klinge and of eastern europe ples results of palynological studies of all these sequences indicate simultaneously a strong increase of environmental oscillations during the very end of the last interglacial and the beginning of the last glaciation this paper discusses possible correlations of these events between regions in central and eastern europe the pronounced climate and environment instability during the interglacial glacial transition could be consistent with the assumption that it is about a natural phenomenon characteristic for transitional stages taking into consideration that currently observed human induced global warming coincides with the natural trend to cooling the study of such transitional stages is important for understanding the underlying processes of the climate changes

direct terrestrial marine correlation demonstrates surprisingly late onset of the last interglacial in central europe an interdisciplinary study of a small sedimentary basin at neumark nord 2 nn2 germany has yielded a high resolution record of the palaeomagnetic blake event which we are able to place at the early part of the last interglacial pollen sequence documented from the same section we use this data to calculate the duration of this stratigraphically important event at 3400 350 yr more importantly the neumark nord 2 data enables precise terrestrial marine correlation for the eemian stage in central europe this shows a remarkably large time lag of ca 5000 yr between the mis 5e peak in the marine record and the start of the last interglacial in this region

burial and exhumation of the long range inlier and its surroundings western newfoundland results of an apatite fission track study the long range inlier a steep sided plateau underlain mainly by grenvillian gneisses is the most prominent topographic feature of western newfoundland apatite fission track analysis of 31 samples from the long range inlier and its surroundings yielded measured apparent ages of 343 152 ma age versus elevation plots track length distributions and model thermal histories indicate that the region experienced slow cooling in the late paleozoic with apparent exhumation rates of 7 9 m ma 1 and cooling rates of 0 08 0 28 c ma 1 model thermal histories suggest that the present upper surface of the long range plateau cooled below 120 c in ordovician times the thermal histories are compatible with but do not require some exhumation of the long range inlier along acadian thrust faults results from early carboniferous sedimentary rocks of the deer lake basin are similar to long range inlier data from similar elevations implying that at some time between 350 and 300 ma the entire region was buried to

multiproxy climate reconstructions for the eemian and early weichselian palaeobotanical coleopteran and periglacial data from 106 sites across northwestern europe have been analysed in order to reconstruct palaeoclimatic conditions during the eemian and early weichselian three time slices in the eemian and four in the early weichselian have been considered in the pinus quercetum mixtum corylus phase of the eemian summer temperatures were probably at their highest and the botanic evidence suggests a southeast to northwest gradient for both the warmest and coldest month coleoptera indicate that the summers in southern england were several degrees warmer than those of present day the climate during thecarpinus picea phase was uniform and oceanic without obvious gradients in the final time slice of the eemian the pinus picea abies phase temperatures of the warmest month seem to drop slightly with some indication of a shift towards a more boreal and suboceanic climate the reconstruction of the palaeoclimate in the herning stadial and rederstall stadial is hampered by the limited number of sites but botanical evidence suggests a gradient in temperature of the coldest month from east to west coleoptera from the herning stadial in central england and eastern germany suggest similarly cold and continental climates during the brorup interstadial and the odderade interstadial the botanical evidence suggests that the minimum mean july temperatures rose to 15 16 c but during the coldest month these temperatures show a gradient between 13 c in the east and 5 c in the west 1998 john wiley sons ltd

k ar and 40ar 39ar geochronology of granitoid rocks from southern nova scotia its bearing on the geological evolution of the meguma zone of the appalachians k ar and or 40ar 39ar apparent ages are reported for 28 samples of biotite and muscovite from nova scotia s south mountain batholith and associated northern satellite stocks in addition 14 mica samples from the southern satellite stocks were dated previous workers using primarily k ar and rb sr techniques have reported a spread of apparent ages ranging from 240 420 ma for these intrusive rocks the present data set is internally consistent and has been calibrated against accepted interlaboratory standards a mean age of 367 ma was obtained for the south mountain batholith and the northern stocks a value consistent with results recently obtained in an rb sr study by clarke and halliday no differences in apparent age among the various phases or clear geographic age distribution patterns were evident satellite stocks in the southern part of the province have in general younger apparent ages clustered in the range 300 320 ma we suggest that in southern areas mica argon systems record the effect

dating mineralization using several isotopic methods an example from the south mountain batholith nova scotia canada abstract granitic plutons in the meguma terrane may be broadly divided into two suites 1 an areally predominant cogenetic suite of peraluminous granitoid rocks tonalite leucogranite and 2 an areally subordinate paraintrusive suite specialized in sn w mo cu f u p zn as which appears to have been produced by fluid interaction with either residual magma or crystallized rock granite related mineralization is generally considered to have developed during terminal stages of magmatic crystallization that lead to metasomatism and hydrothermal alteration previous geochronological data have suggested that the main cogenetic suite was emplaced at 350 375 ma whereas some of the paraintrusive suite is markedly younger 250 350 ma the apparently large time interval between the intrusion of the cogenetic suite and some of the mineralization suggests that they are not coeval and has led to the conclusions that the younger mineralization may be related to later magmatism and or tectonothermal events rocks associated with two mineral occurrences in the south mountain batholith that had previously yielded anomalously young isotopic ages millet brook and westfield have been analyzed for u pb and ar isotopes in an attempt to resolve this dilemma new geochronological data from the millet brook area indicate that intrusion of granodiorite at 377 5 3 ma nearly concordant monazite age was closely followed by intrusion of most other phases all of which had cooled through 375 c closure temperature for ar in muscovite by 377 373 6 ma 40 ar 39 ar plateau ages new data from westfield indicate that a paraintrusive porphyry was intruded at 385 2 ma upper intercept of a chord through four nearly concordant zircon fractions and that greisen muscovite cooled through the closure temperature by 368 2 6 ma 40 ar 39 ar plateau age these data indicate that a previously reported rb sr whole rock isochron age of 270 ma at westfield reflect isotopic resetting that occurred below the blocking temperature for 40 ar 39 ar in muscovite 375 c clearly further rb sr analysis is required to document this process other 250 300 ma ages in the meguma terrane are recorded along the tobeatic fault zone away from the fault ages increase upto 370 ma suggesting that the fault may have acted as an important pathway for fluids and heat that facilitated isotopic resetting rb sr whole rock and mineral systems may be affected after formation of an alteration assemblage associated with mineralization by the migration of rb and its concentration in secondary minerals

oxygen isotope analysis of equus teeth evidences early eemian and early weichselian palaeotemperatures at the middle palaeolithic site of neumark nord 2 saxony anhalt germany abstract here we present phosphate oxygen isotope 18opo4 data from horse equus sp tooth enamel bioapatite from early eemian and early weichselian find levels at the archaeological site of neumark nord 2 germany based on the relationship between 18opo4 of bioapatite body water local precipitation and air temperature these data are used to reconstruct palaeoclimatic conditions contemporary to the different phases of neanderthal activity at the site bulk enamel samples representing one year of growth were taken from horse teeth from early eemian nn2 2b 121 5 ka and nn2 1c and early weichselian nn2 0 93 7 ka find levels and 18opo4 values were then utilised to calculate 18o of local environmental water and mean annual air temperatures mats during these phases of mis5 results indicate that during the early eemian mat was 9 c with some evidence of variability through time although 3 c lower the calculated early weichselian mat exceeds that indicated by other local and regional climate proxy datasets suggesting that neanderthal activity may have coincided with more ameliorate phases of the early weichselian in this area

stable climatic conditions in central germany during the last interglacial stable isotopic data from the high resolution limnic sequence in the opencast mine at grobern central germany confirm the relatively stable climate of the last interglacial deduced from pollen analyses after significant warming during the transition from the saalian to the eemian stable warm climatic conditions set in once the climatic optimum was reached in the course of biozones e4 to e5 from the middle of biozone e6b a gradual temperature decrease can be observed reaching a minimum at the start of biozone e7 the division of the early weichselian glacial in central germany into two stadials herning rederstall and two interstadials brorup odderade is also documented by the findings copyright 2000 john wiley sons ltd

geology stratigraphy and palaeoenvironmental evolution of the stephanorhinus kirchbergensis bearing quaternary palaeolake s of gorzow wielkopolski nw poland central europe

late carboniferous and early permian drainage patterns in atlantic canada paleoflow data have been compiled for late carboniferous late westphalian a to early permian alluvial deposits over a large area of atlantic canada the data which include more than 36 000 measurements of large scale trough cross strata indicate a predominantly northeasterly paleoflow and suggest that a major source area lay to the southwest of the region throughout the 30 ma period represented uplands within the basin deflected paleoflow and probably formed important local drainage and sediment sources tectonostratigraphic analysis suggests that the drainage originated in the fold and thrust belt of the central appalachians and parts of the northern appalachians rivers probably followed northeast oriented structural lineaments through the older acadian mountains of the northern appalachians a considerable proportion of the rising orogen s drainage and probably detritus may have traversed basins along the strike of the mountain belt a situation analogous to that of the modern himalayas

geophysical and structural signatures of syntectonic batholith construction the south mountain batholith meguma terrane nova scotia summary the late devonian south mountain batholith is a very large 7000 km2 composite peraluminous granitoid complex situated within the meguma terrane of the northern appalachians it is made up of two suites of granodioritic to leucogranitic plutons emplaced at approximately 380 370 ma during the acadian orogeny i e during the collision of gondwana with the eastern margin of north america a significant geophysical and geological database makes the south mountain batholith a type example of a very large syntectonic batholith emplaced within a collisional orogen gravity models reveal the plutons have flat or gently dipping floors at approximately 7 0 km depth and aspect ratios 651 they are underlain by deeper 10 km elongate northeast southwest trending roots that may indicate magma feeder zones dyke transport of granitic magma and the progressive construction of plutons by sheet injections are supported by field observations and by mapping of the anisotropy of magnetic susceptibility at the pluton scale the very narrow deformation aureole within the country rocks suggests lateral spreading of the plutons was not the main space creation mechanism during emplacement space was mostly created by vertical displacements of country rocks the data are consistent with a laccolithic model for syntectonic batholith assembly the laccolithic plutons may have been emplaced at the base of the meguma supergroup metasedimentary rocks suggesting a maximum thickness of approximately 7 0 km for the supracrustal rocks in the meguma terrane

ice volume and sea level during the last interglacial during the last interglacial period 125 000 years ago sea level was at least several meters higher than at present with substantial variability observed for peak sea level at geographically diverse sites speculation that the west antarctic ice sheet collapsed during the last interglacial period has drawn particular interest to understanding climate and ice sheet dynamics during this time interval we provide an internally consistent database of coral u th ages to assess last interglacial sea level observations in the context of isostatic modeling and stratigraphic evidence these data indicate that global eustatic sea level peaked 5 5 to 9 meters above present sea level requiring smaller ice sheets in both greenland and antarctica relative to today and indicating strong sea level sensitivity to small changes in radiative forcing

the scotian basin offshore nova scotia thermal history and provenance of sandstones from apatite fission track and 40ar 39ar data apatite fission track and 40ar 39ar age spectrum data from sandstone drill core minerals taken from depths of 2 5 km in nine wells from the scotian basin are presented and interpreted in terms of the thermal history of the basin and the provenance of its sediments the focus of the study is a comparison of the data from these thermochronometers with each other and with previously published vitrinite reflectance and aromatization isomerization a i reactions in biomarker compounds from the same or nearby wells apatite fission track ages are generally in agreement with expectations in that they trend to zero at a depth of 4 km corrected bottom hole temperature 120 c shallower lower present temperature samples are partially annealed the degree of partial annealing correlates closely with the degree of a i reactions both thermal indicators are activated over the temperature range 60 120 c samples from two wells mic mac j 77 and erie d 26 are anomalous they are more annealed than present formati

palaeoecological investigations and 230th u dating of eemian interglacial peat sequence of banzin mecklenburg western pomerania ne germany abstract a novel occurrence of an eemian interglacial peat was identified in 2011 in a short lived outcrop of the nel pipeline trench near the village of banzin germany the profiles are situated in a shallow kettle hole within the undulated landscape of the saalian glaciation the distribution of dominantly till lithofacies in the banzin area confirms the regional trend of saalian tills with a locally higher abundance of cretaceous clasts in the banzin kettle at a depth of 2 2 m lies a 0 5 m thick strongly compressed eemian peat layer the buried eemian peat layer is deformed by ice wedge pseudo morphological and mega crack structures indicating a strong periglacial influence during weichselian stadial phases the post eemian sequence is subdivided into three units beginning with a mixture of aeolian and gelifluction deposits which are also modified by cryostructures the top of the banzin sequence is covered by a 0 5 m thick colluvisol layer of redeposited humic loam from the late weichselian holocene the uppermost unit suggests that solifluction processes occurred in the last few hundred years likely driven by intensive anthropogenic influence limnic sedimentation began during the late saalian period in a landscape characterized by herbaceous vegetation and heliophytes during the latest interval of saalian deglaciation shallow waters of the basin most likely attained a depth below 3 m and were abundant in calcium carbonate the beginning of eemian interglacial peat accumulation mis 5e is characterized by a dominance of light birch forests followed by pine the ensuing optimum climate was dominated by the encroachment of oak forests and then hazel oak forest and sedimentation ceased in the basin during this phase at the climatic optimum pz iii iv the eemian peat included remains of ceratophyllum submersum and species of higher temperature requirements the banzin basin gradually became shallower and overgrown until the closing of its open water at the end of phase iii iva the lack of cladocera species composition in the eemian sequence proves isolated conditions of a shallow reservoir we present the first results from ne germany for eemian peat bog samples dated by the u th disequilibrium method 230 th u using leachate alone l l and total sample dissolution tsd analytical techniques isochron corrected 230 th u ages of 118 8 10 ka l l and 121 9 13 ka tsd were obtained both 230 th u dates 118 121 ka obtained using two different techniques confirm the biostratigraphical classification into the eemian interglacial

a long pollen record from lac du bouchet massif central france for the period ca 325 to 100 ka bp ois 9c to ois 5e abstract pollen analysis was carried out on sediments older than the wurm pleniglacial ois 4 in two new sequences h and i derived from the centre of lac du bouchet massif central the inferred vegetation history enables for the first time in france five temperate episodes to be defined which pre date the last interglacial these temperate episodes alternate with episodes during which the changes in vegetation are indicative of glacial climates comparison of these climatic episodes with the oceanic isotope record shows that the pollen record of sequences h and i from lac du bouchet spans the time interval from ois 9c ussel interstadial to ois 5e ribains eemian interglacial in the organic sediments from the amargiers interstadial ois 9a a trachytic layer ar ar dated to ca 275 ka enables a correlation to be established with the upper part of a sequence derived from the nearby praclaux crater the lower part of this sequence being of holsteinian age ois 11c the cross dating of the pollen sequences from lac du bouchet cores h i and d and from praclaux provides a complete record from the massif central southern france of successive glacial and interglacial episodes that span the last ca 400 ka that is the interval from the holsteinian to the holocene

origin of topaz bearing and related peraluminous granites of the late devonian davis lake pluton nova scotia canada crystal versus fluid fractionation abstract the davis lake pluton in the late devonian south mountain batholith in southwestern nova scotia canada is composed of peraluminous leucomonzogranites and subordinate topaz bearing leucogranites that host greisens and a primary tin deposit the concentrations of incompatible trace elements e g rb li u f ta and sn and element e g k rb nb ta and la sm and isotopic ratios e g 206 pb 204 pb and 87 sr 86 sr display a spatial zonation the granitic rocks were generated by extensive fractional crystallization of major phases feldspars and biotite and accessory minerals monazite apatite and zircon in a compositionally zoned magma chamber fractional crystallization of the evolving f rich peraluminous granitic magma was accompanied particularly in later stages by fluid fractionation involving fluorine complexing fluid fractionation was a major differentiation process during the terminal stages of the pluton s evolution it played an important role in the genesis of the evolved rocks which are characterized by low k rb 24 150 nb ta 1 6 la sm 1 5 4 and eu eu 0 01 0 3 ratios these ratios as well as the enhanced concentrations of li rb u ta and sn in these rocks correlate with f fluorine rich fluids modified the rb sr and u pb ratios which produced the distinct variations of 87 sr 86 sr and 206 pb 204 pb isotopic ratios the parent magma was formed by dehydration melting of lower crustal metasedimentary rocks the melting was related to crustal thickening in association with terrane and collision along the eastern margin of the appalachians

paleoclimate and paleoceanography over the past 20 000 yr in the mediterranean sea basins as indicated by sediment elemental proxies abstract marine sediments record paleoenvironmental changes over time through variations in major and trace element concentrations the main objective of this paper is to review such changes in the mediterranean sea basins over the last 20 ka using the inorganic chemistry and mineralogy of marine sediment records elemental ratio proxies that are mostly used are discussed and the uncertainties involved in using them for paleoclimate and paleoceanographic reconstructions are evaluated the focus on the mediterranean region is based on the sensitivity of this region to global climate changes due to its semi enclosed nature the elemental ratios that have been particularly useful for reconstructing terrigenous inputs into the mediterranean have been ti al and zr al ratios as proxies for eolian dust input and mg al k al and rb al ratios as proxies for fluvial input redox sensitive elements e g u mo v co ni cr have provided reliable reconstructions of oxygen conditions at the time of deposition some of these elements are also particularly susceptible to post depositional remobilization and record diagenetic processes instead of the original environmental signatures regarding productivity fluctuations most of the paleoproductivity reconstructions are based on the abundance of barite and ba excess algorithms the biogeochemistry of ba is however not fully understood and mechanisms for barite precipitation in the water column are not yet known two case studies are presented the eastern mediterranean sapropel s1 deposited between 10 8 and 6 1 cal ka bp and the westernmost mediterranean paleoclimate record over the last 20 ka

the distribution of gold in rocks and minerals of the meguma group of nova scotia canada abstract rocks and constituent minerals of the meguma group from southeastern nova scotia were analyzed for gold by far the highest levels 4311 ng g ppb whole rocks 1 0 ppb and other minerals

vegetation patterns under climate changes in the eemian and early weichselian in central europe inferred from a palynological sequence from ustkow central poland abstract this paper presents a fresh examination of a pollen profile from ustkow central poland which after preliminary results was thought to span a period between the early eemian mis 5e and the upper pleni weichselian mis 3 the newly obtained results confirmed the age assessment of the bottom series but revealed a much older age for the uppermost part of the profile as far back as the rederstall stadial mis 5b palynological research showed slightly different patterns of vegetation in comparison to other sites located in central europe among them were an early ulmus maximum coinciding with the betula optimum in the early eemian a relatively late optimum of taxus baccata during the decline of the middle eemian and a distinct division of the older part of the late eemian into phases of abies picea and picea pinus forest domination the herning stadial mis 5d falls into a typical bipartition reflected by heathland domination during its older part and the prevalence of juniperus thickets and artemisia poaceae steppe during its younger part which makes this succession similar to those from northern germany the pollen spectra reflecting the brorup interstadial mis 5c distinctly revealed an intra brorup cold oscillation rarely detected in profiles from central europe and a period of larix dominated forests during the latest part of the interstadial extraordinarily high percentages exceeding 15 of the total pollen sum local pollen taxa together with the lithological composition of deposits revealed that there was a water body in the area during the periods of the late saalian early eemian transition middle eemian the decline of the tilia phase the herning stadial mis 5d the early brorup interstadial mis 5c and the rederstall stadial mis 5b between these time intervals a poor and or rich fen and or bog functioned

dating transcurrent terrane accretion an example from the meguma and avalon composite terranes in the northern appalachians the polygenetic minas geofracture separates the meguma and avalon composite terranes of the maritime appalachians dynamically recrystallized muscovite and biotite occur within d3 shear zones which developed during dextral movement along the geofracture these record 40ar 39ar plateau ages between circa 360 and 370 ma comparable plateau ages are recorded by micas within undeformed portions of granitic plutons and their low pressure contact metamorphic aureoles these are similar to u pb ages previously reported for igneous monazite therefore indicating relatively rapid postmagmatic cooling at shallow crustal levels the d3 fabrics were superimposed on earlier s1 structures which formed during initial amalgamation of the meguma and avalon composite terranes whole rock slate phyllite samples collected outside high temperature portions of the plutonic contact aureoles yield 40ar 39ar plateau ages which correspond to groupings of circa 400 395 ma 390 385 ma and 380 375 ma these are interpreted to date diachronous formation of the s1 fabrics and concomitant low grade regional metamorphism in the circa 25 ma between initial amalgamation and granitic plutonism it is inferred that there was a slow rise of isotherms through the crust as a result of overthrust tectonic thickening this led to crustal melting and the production of widespread granitic magmas which were emplaced immediately prior to d3 dextral shearing

a probabilistic assessment of sea level variations within the last interglacial stage robert e kopp 1 frederik j simons 2 jerry x mitrovica 3 adam c maloof2 and michael oppenheimer2 4 1department of earth and planetary sciences and rutgers energy institute rutgers university piscataway nj 08854 usa e mail robert kopp rutgers edu 2department of geosciences princeton university princeton nj 08544 usa 3department of earth and planetary sciences harvard university cambridge ma 02138 usa 4woodrow wilson school of public and international affairs princeton university princeton nj 08544 usa

the petrology geochemistry and economic potential of the musquodoboit batholith nova scotia the musquodoboit batholith of southwestern nova scotia is a massive post tectonic granitoid intrusion that was emplaced into the regionally deformed and metamorphosed meguma group metasedimentary rocks the batholith is composed primarily of medium to coarse grained monzogranites into which two small 1 km2 porphyries and numerous dykes have been injected all rocks contain quartz alkali feldspar plagioclase muscovite and biotite with the exception of some leucocratic dykes cordierite is a major constituent in most monzogranitic rocks and also occurs in some leucocratic dykes andalusite and garnet 0are also present as accessory phases in some rocks major element chemical analyses indicate that all rock types in the musquodoboit batholith are peraluminous compositions resemble those of the eastern part south mountain batholith however slightly higher concentrations of al2o3 and p2o5 distinguish the musquodoboit batholith from the central part of the south mountain batholith major and trace

precise u pb dating of meguma basement xenoliths new evidence for avalonian underthrusting u pb zircon and monazite dates for granulite facies basement xenoliths from the popes harbour dyke on the eastern shore of nova scotia provide strong evidence that the meguma terrane overlies avalo

an attempt at correlation between the velay pollen sequence and the middle pleistocene stratigraphy from central europe abstract long continuous lacustrine sequences constitute on the continent a precious tool for coupling the long term continental environmental changes with deep sea and ice core records using the count from the top method moreover they can contribute to long distance correlation on the continent itself and thus help to classify discontinuous sedimentary records palynostratigraphical correlation is proposed here between the velay long sequence and the late middle pleistocene series from central europe with special attention to temperate episodes the similarities between the praclaux and the holsteinian interglacial suggest that they are both contemporaneous with marine isotopic stage mis 11 even if absolute dates are still divergent the evidence of two major warm periods with an interglacial type of vegetation between the holsteinian and the eemian is confirmed by the velay record

structural and sedimentary history of the quaco head area southern new brunswick remapping of the quaco head area of southern new brunswick has revealed a more complex structure than had been previously documented the structure is dominated by two major thrust faults that dip to the south and southeast at between 35 and 45 the lower younger thrust emplaces precambrian basalts and tuffaceous siltstones coldbrook group over alluvial sediments of the boss point and tynemouth creek formations westphalian a b resting unconformably on the upper surface of the basalt is a thin layer 10 m of marine basal windsor group limestone disconformably overlain by alluvial conglomerates of inferred hopewell group age this sequence is truncated by an older southeast dipping thrust fault to the southeast of which lie hopewell conglomerates overturned towards the west and northwest the latter sequence probably forms the lower limb of a large recumbent fold folding and thrusting in the quaco head area may have begun during westphalian b times although major movement was probably post westphalian c and occurred contemporaneously with dextral strike slip movement on the minas geofracture following this alleghenian variscan deformation the area underwent deep erosion prior to the deposition of a thick sequence of triassic alluvial sediments the more southerly reverse fault was reactivated as a normal fault during a phase of late triassic or jurassic faulting along the bay of fundy that was probably related to early atlantic rifting

alleghanian polyphase deformation of the hope valley shear zone southeastern new england structural petrographical and rb sr isotopic studies in the highly deformed basement rocks of southern rhode island have allowed the identification of the southern continuation of the hope valley shear zone hvsz previous work recognized the hvsz as an alleghanian tectonic boundary separating the distinct late precambrian esmond dedham and hope valley terranes in southeastern new england two important components of the esmond dedham terrane the late precambrian ponaganset gneiss and the devonian scituate granite gneiss now have been traced with structural continuity into southern rhode island the distribution of these gneissic units and their structures shows that the southern segment of the hvsz has been strongly deformed abruptly deflecting it from a nw se orientation to a n s trend the deflection of the hvsz marks an abrupt structural boundary between two distinct regionally developed mineral lineation domains a northwestern domain with north to nnw trends characteristic of most of the hvsz and a southeastern domain with ne trends structural relations suggest that all mineral lineations were originally parallel along the hvsz with a north to nnw trend the deflection formed during a subsequent phase of ductile right lateral shear producing a clockwise rotation of both lineations and the hvsz in southern rhode island thus basement gneisses in southeastern new england have suffered polyphase alleghanian deformation at high metamorphic grades it has been argued that during the late paleozoic southern new england was located in a structural transition zone between convergent tectonics in the central and southern appalachians and wrench tectonics in the northern appalachians the structural link between these two distinct tectonic regimes is an e w right lateral transcurrent fault the late dextral shear deformation described in southern rhode island basement rocks appears to have resulted from right lateral movement at depth within this transcurrent fault zone

timing and duration of the last interglacial evidence for a restricted interval of widespread coral reef growth abstract we report new mass spectrometric u series ages for eight last interglacial fossil reefs along the continental margin of western australia corals were selected in growth position from localities that are characterized by apparently low levels of diagenesis and relative tectonic stability so that the fossil reefs provide critical information on last interglacial sea levels without requiring corrections for tectonic movements in addition we have improved the constraint on the timing of onset of reef growth by recovering drill core coral from the base of the reefs uranium and thorium isotopes were measured with high levels of precision leading to improvements in age resolution and allowing samples which have undergone diagenetic exchange of uranium and thorium to be more easily identified and discarded these data supplement our previous results for rottnest island and leander point leading to more than seventy mass spectrometric u series ages from which constraints can be placed on the timing duration and character of the last interglacial sea level highstand reliable ages show that reef growth started contemporaneously at 128 1 ka along the entire western australian coastline while relative sea levels were at least 3 m above the present level because western australia is located far from the former penultimate glacial maximum ice sheets and are not significantly effected by glacial unloading these data constrain the timing of onset of the last interglacial period to 128 1 ka assuming reef growth started soon after sea level approached interglacial levels a unique regressive reef sequence at mangrove bay constrains the timing of termination of the last interglacial period to 116 1 ka the major episode of reef building however both globally and locally along the western australian coast is restricted to a very narrow interval occurring from 128 ka and 121 ka suggesting that global ocean surface temperatures were warm and or sea levels were stable enough to allow prolific reef growth only during the earlier part of the last interglacial

paleomagnetism of the gays river zinc lead deposit nova scotia pennsylvanian ore genesis the gays river zinc lead deposit is the largest known mississippi valley type deposit in the mississippian windsor group of atlantic canada thermal and af demagnetization show that both ore and host rock have very similar magnetic characteristics stability tests constrain the magnetization to be mid mississippian to late pennsylvanian the pole position from the ore and host rock sites falls next to the pennsylvanian apw path suggesting an 8 clockwise rotation of the meguma platform relative to the craton regional thermal history and geochemical evidence suggest that the zinc lead ore magnetization and host rock remagnetization are coeval

offshore continuation of meguma terrane southwestern nova scotia eight short drill cores have been examined from the continental shelf southwest of nova scotia four cores recovered granitoid rocks of two types ilmenite bearing granitoid rocks petrographically and geochemically resemble granodiorites of the south mountain batholith and granites of the seal island pluton magnetite bearing granitoid rocks are also peraluminous but have no exact analogues onshore in nova scotia two cores recovered metamorphic rocks in a small area 50 km south of seal island one consits of chlorite muscovite quartz schist geochemically similar to rocks of the halifax formation the second sampled epidote chlorite quartz schist similar to metavolcanic rocks of the white rock formation one further core sampled quartzite and another sampled a metavolcanic rock possibly erratic the regional extent of these lithotypes can be inferred from gravity and aeromagnetic data regional gravity data suggest the presence of a large granite body off southwestern nova scotia in this area magneti

aspects of seismic character and extent of upper carboniferous coal measures gulf of st lawrence and sydney basins abstract a seismic facies related to upper carboniferous coal measures has been mapped in the gulf of st lawrence sydney basin region of atlantic canada the inferred original extent of this area of coal deposition is over 100 000 km 2 which is two to three orders of magnitude larger than the fault bounded terrestrial coal basins on the surrounding landmass the depositional continuity of this seismic sequence is on the scale of cyclothem deposition in the illinois basin and mid continent basin region of the united states and suggests an analogous stable cratonic shelf setting for the gulf of st lawrence sydney basin region in paleogeographic reconstructions for the late carboniferous cyclothems in a paleoequatorial setting in the mid continent basin of euramerica have been correlated with cyclothems in a similar setting on the russian platform the gulf of st lawrence and sydney basins lie midway between these two regions it will be an interesting test of these correlations to determine the exact age and environment of the coal measures seismic facies

late paleozoic transcurrent tectonic assembly of the central appalachian piedmont recent investigations in south eastern pennsylvania and northern maryland have demonstrated a major anastomosing strike slip shear system the pleasant grove huntingdon valley shear system emerges from beneath the coastal plain cover at trenton new jersey and extends to the area west of baltimore maryland where it is overlain by the culpepper mesozoic rift basin the sense of offset across this system is dextral in the susquehanna river region and north of the shear zone the rocks of the octoraro formation contain evidence for two metamorphisms and deformations prior to strike slip shearing whereas south of the shear zone the peters creek formation contains evidence for only one the discordance in metamorphic and deformational history across the shear zone suggests the now juxtaposed rocks originated in different parts of the orogen although conclusive ages for the strike slip deformation do not exist at this time the timing of deformation is loosely constrained where the shear system crosscuts known taconian structures in the piedmont comparison of deformation style with other regions in the appalachian suggests the pleasant grove huntingdon valley shear system is related to alleghanian transcurrent tectonics in the piedmont palinspastic reconstruction of the pleasant grove huntingdon valley shear system reveals fundamental problems in current tectonic models for the central appalachian piedmont a minimum of 150 km of dextral offset is proposed for the pleasant grove huntingdon valley shear system based on reconstruction of the cambrian ordovician shelf edge between northern maryland and southeastern new york displacement of this magnitude can account for the previously proposed tectonic models that portray a failed iapetan rift block and microcontinent that contains the baltimore grenvillian massifs even though a history of early orthogonal collision is preserved within discrete structural blocks transcurrent shearing has greatly influenced the distribution of those blocks models not including the strike slip component of tectonic assembly need serious reconsideration as evidence grows that the magnitude of orogen parallel displacement is equal to or larger than the orthogonal component

dating the quaternary progress in luminescence dating of sediments abstract luminescence dating comprises a collection of numerical age techniques that are among the most significant chronological tools currently used in quaternary research this paper briefly reviews the key historical developments in luminescence dating from its roots in thermoluminescence dating of heated minerals to the development of optical dating methods for sunlight exposed sediments we describe the principles and practicalities of the various techniques commonly used in luminescence dating including multiple aliquot single aliquot and single grain procedures and we discuss some of the latest approaches to recognising and minimising potential errors in age estimation e g by means of component analysis and dose distribution methods in optical dating the overview also introduces the other papers in this special issue of quaternary science reviews which address a selection of important issues in basic research technique development and application of luminescence dating to critical questions in the geological and archaeological sciences illustrated with examples from around the world and the last million years of earth history

interpreting luminescence data from a portable osl reader three case studies in fluvial settings optically stimulated luminescence osl is a technique that has been applied from the mid 1980s mainly for sediment dating the osl technique is based on sample stimulation by light to determine the luminescence signal that is stored in the crystal lattices of sediment grains after deposition burial by later sediment and subsequent exposure to ionizing radiation from radioactive elements in the surrounding sediment in such sediment dating two parameters are required the equivalent dose i e the luminescence signal stored in the grains and the dose rate i e the ionizing energy from and radiation emitted by naturally occurring radioisotopes in the deposit plus the effects of cosmic radiation in this research the osl technique is not used for dating the study goal is to analyse only the luminescence signals the total photon counts in polymineral samples obtained after light stimulation in the blue blsl and infrared irsl wavelengths using a portable osl reader designed and built at the scottish universities environmental research centre suerc three fluvial case studies from cambodia australia and mexico are used to illustrate the geomorphological interpretations possible with the portable osl reader data from sediments resulting from a range of different depositional processes the case studies show that aspects of sediment s transport and depositional processes can be inferred from the portable osl reader data providing valuable insights into geomorphological history copyright 2010 john wiley sons ltd

geochemical behavior of sulfur in granitoids during intrusion of the south mountain batholith nova scotia canada abstract a detailed stable isotope s o and elemental major trace s content study of peraluminous s type granites and granodiorites of the south mountain batholith and the meguma group metasediments into which the batholith was intruded has been conducted on a regional and local scale near mt uniacke sulfur contents of the metasediments range from 5 to 2440 ppm and 34 s ranges from 3 7 to 26 3 sulfur contents of the igneous rocks range from 6 to 570 ppm with the granites 20 ppm having lower sulfur contents than the granodiorites 300 ppm approximately 30 to 60 of the sulfur in the granodiorites is present as pyrrhotite a late phase with most of the remainder being present as sulfur substituted into biotite an early phase 18 oq quartz values of the mt uniacke granodiorites are heavy a 12 2 indicating formation of the magmas by partial melting of sedimentary rocks major element variations suggest that the granites are related to the granodiorites by fractional crystallization of plagioclase quartz and biotite comparison of the sulfur contents of the granodiorites with experimental determinations of sulfur solubility suggest that the distribution coefficient of sulfur d s between the cumulate and the magma during fractional crystallization 4 the regional granodiorites have a relatively restricted range of 34 s values 5 4 to 8 4 while the regional granites have a wide range of 34 s values 1 6 to 15 0 granodiorites at mt uniacke with normal magmatic values 0 76 to 1 42 for 18 o quartz feldspar have 34 s values between 6 6 and 12 3 and show good negative correlations between 34 s and s feo and mgo contents some granodiorites at mt uniacke have anomalously low sulfur contents for their major element composition and 18 o quartz feldspar values 0 45 to 0 67 indicate that these samples have undergone hydrothermal alteration and this alteration event is probably responsible for the low sulfur contents a number of processes have been considered in order to understand the variations of 34 s partial melting of inhomogeneous source rocks may be responsible for some of the regional 34 s variations but this implies that the granites are not genetically related to the granodiorites inhomogeneous source rocks are an unlikely explanation for the systematic variations of 34 s observed over only a few kilometres at mt uniacke rayleigh fractionation accompanying the fractional crystallization of biotite 34 s pyrrhotites silicate s 0 5 to 1 0 can account for only a small component of the observed 34 s variations the assimilation of isotopically variable sulfur derived from the meguma group metasediments during fractional crystallization combined assimilation fractional crystallization or afc provides the best explanation for the 34 s variations transfer of sulfur from the country rock may have been possible by either bulk afc where all of the country rock material is incorporated into the magma or by selective afc where sulfur and other volatile elements only are transferred from the country rock into the magma selective afc could have been effected by a sloping mechanism of intrusion followed by the heating of country rock xenoliths to the point where extensive desulfidation reactions took place with sulfur being transferred from the country rock to the magma by a fluid phase

landscape evolution in the periglacial zone of eastern europe since mis5 proxies from paleosols and sediments of the cheremoshnik key site upper volga russia abstract a variety of studies of the re examined new exposure late pleistocene key section cheremoshnik east european plain middle of the volga basin of yaroslavl was conducted on a new methodological level using modern methods for the first time a series of paleosols mis5 mis1 from the section offering significant information in regard to chronostratigraphy and landscape evolution have been studied in detail and dated an excavation 7 m deep reveals a soil sediment stratum which formed over the course of 115 ka in an accumulative beam like terrace and consists of five lithological layers and six pedostratigraphical units the base of the section was determined to be an early mikulino peat dark humus paleosol which marked incipient subaerial pedogenesis on the moscow riss ii moraine and was covered with a thickness of gyttja with a peat horizon histosol which had formed 114 115 ka and was reliably dated using uranium thorium dating the following paleosols were successfully identified within the series of weak stone gullied channel sediments within the valdai w rm thickness from bottom to top 1 bryansk paleosol mis3 gleysol with three pedogenesis rhythms 2 trubchevskaya pale sol gleyic turbic cryosol mis2 and 3 pedosediment formed at the end of the b lling interstadial mis2 terminal pleistocene formations are marked with a gravelly stratum on the section s surface formed during the preboreal period recent regosol formed on loess like loam deposits was identified at the top of the whole soil sediment stratum the 14c age of the paleosol humus varied between 27 500 and 11 400 cal bp the paleosols represent the northernmost occurrence of mis5 mis2 fossil soil in europe dominated by features of gleyzation cryogenic aggregation cracking and humus and peat formation pollen analysis results allowed estimation of changes in vegetation cover climatic conditions and the age of deposit sedimentation for the period from the moskow late glacial to the valdai late glacial and early holocene times successive stages in the development of vegetation high contents of alder and hazel pollen and the climax and distinct appearance of broadleaf trees relate the formation of biogenic sediments lpaz 2 6 in the cheremoshnik section to the mikulino interglacial valdai mis4 mis2 glacial sediment is absent within the investigated area

40ar 39ar ages from the narragansett basin and southern rhode island basement terrane their bearing on the extent and timing of alleghenian tectonothermal events in new england pennsylvanian sedimentary rocks record the effects of progressive barrovian metamorphism and polydeformation in the narragansett basin of rhode island whole rock phyllite samples from low grade portions of this terrane display internally concordant 40 ar 39 ar age spectra with plateau ages of 248 to 258 m y four samples biotite from higher grade rocks records plateau ages of 240 to 248 m y eight samples similar 40 ar 39 ar biotite ages are displayed westward across the southern rhode island basement terrane 239 to 250 m y nine samples although coexisting hornblende records slightly older plateau ages of 255 m y two samples the 40 ar 39 ar plateau ages are interpreted to date times of post metamorphic cooling through temperatures required for argon retention in the various mineral phases examined the ages suggest that a distinct late paleozoic alleghenian thermal event affected much of southern rhode island together with the depositional ages of the variably metamorphosed pennsylvanian rocks westphalian b stephanian a or b the 40 ar 39 ar data permit calibration of the sequence of alleghenian tectonothermal events recorded in the narragansett basin the controls suggest a permian event lasting about 40 to 50 m y between initial barrovian regional metamorphism and synchronous d 1 d 2 ductile deformation between 295 and 275 m y and post d 3 cooling below argon retention temperatures between 250 and 240 m y

thermal history of the southwestern meguma zone nova scotia from an 40ar 39ar and fission track dating study of intrusive rocks two geologically distinct regions within the meguma terrane have been studied in detail and are shown to have contrasting thermal histories this conclusion is based on 31 new 40ar 39ar age spectra on micas k feldspars and hornblendes from several of the plutons in southern nova scotia which are satellites to the much larger south mountain batholith smb in addition we report four k feldspar age spectra from a locality in the northeastern part of the smb and seven fission track ages from both the southern and northern areas the complex age spectrum of hornblende from a mafic phase associated with the bamngton passage pluton suggests a minimum intrusive age of 385 ma a result consistent with geologic evidence that this pluton represents an early less evolved magmatic pulse later intrusive activity appears to have been coeval with the intrusion of the smb at ca 370 ma ago in the southern region argon clocks in feldspars were completely reset and mica clocks variably reset by a later thermal event the cumulative geochronologic and geologic evidence constrains this event to 300 320 ma ago in the smb this alleghanianl hercynian thermal disturbance is much less pronounced and appears to be localized to small areas that are often associated with economic mineralization k feldspars from the southern plutons record an episode of argon loss 220 230 ma ago which is less evident in the smb to the north upper triassic dike injection in the southern region associated with the initial rifting phase of the canadian atlantic margin accompanied this milder thermal pulse apatites in the two regions record a mean fission track age of ca 180 ma which we attribute to the final cooling of the terrane below about 100 c the timing of this event coincides with regional uplift recorded in sedimentary sequences along much of the maritime continental shelf deux kgions gtologiques distinctes inttgkes au terrane de meguma ont ctt ctudites en dctai1 et leurs histoires thermales

plutonic and hydrothermal events in the ackley granite southeast newfoundland as indicated by total fusion 40ar 39ar geochronology results of total fusion 40ar 39ar dating eight biotites four muscovites and one hornblende of magmatic and hydrothermal stages of the high silica chemically zoned ackley granite indicate three distinct episodes of magmatic activity viz 410 378 374 and 355 ma and that the metallogenic system w sn mo evolved synchronously with only one of the magmatic phases the oldest suite is indicated by two biotite dates at 410 4 4 4 and 392 5 7 6 ma which are themselves considered as representing partial resetting related to a tectonothermal event of acadian age thus the 410 ma age offers the best estimate of intrusion although it must be considered a minimum the main magmatic pulse for the ackley granite is indicated by dates between 378 and 374 ma with most of these phases occurring in the southern part of the complex concordant hornblende biotite ages 374 8 3 8 and 372 3 4 8 ma respectively for one of the southern phases rencontre lake granite suggests rapid cooling for this part o

delineating stratigraphic breaks at the bases of postglacial eolian dunes in central alberta canada using a portable osl reader temporal constraints for the late pleistocene deposition of eolian dunes that occur in central and northern alberta canada can be provided by dating sediments from the dune bases using luminescence techniques in places however the postglacial dunes overlie glaciofluvial sands that resemble the eolian deposits in texture such that demarcating the bases of the dunes is often problematic in this study we address the problem by employing a portable optically stimulated luminescence osl reader to construct luminescence profiles that depict luminescence signal variation with depth with the portable osl reader measurement can be performed on bulk sediments negating the need for laborious separation procedures to isolate pure mineral fractions as is required in regular luminescence dating measurements can also be carried out in the field permitting quicker decision making during sample collection results from this study presented as depth variations of feldspar derived infrared stimulated luminescence irsl signals and predominantly quartz generated post ir blue osl signals show that luminescence profiling enables one to distinguish between eolian deposits that make up the dunes from the underlying non eolian sands the identification of such cryptostratigraphic interfaces is made possible by differences in the dosimetric histories of the sediments the delineation of the dune bases allows targeted sampling that yields best luminescence age approximations for the initiation of postglacial eolian deposition in the region luminescence profiling of eolian sequences would also in theory permit the identification of depositional breaks of extended duration copyright 2012 john wiley sons ltd

eemian and early weichselian temperature and precipitation variability in northern germany abstract dramatic changes in european vegetation occurred during the transition from the eemian interglacial to weichselian glacial climates correlative with major changes in global ice core and marine records quantitative knowledge of climate change is important for understanding of the climate system and for climate modelling for which reconstructions of this transitional period are of special interest however it has been difficult to quantify the climatic changes involved in the eemian to early weichselian transition from terrestrial archives due to the lack of modern vegetation analogues to circumvent this problem we applied a suitable multivariate probabilistic approach to pollen and plant macrofossil assemblages to reconstruct temperature and precipitation for this transition in central europe our reconstructions span the interval from the beginning of the eemian marine isotope stage mis 5e to the odderade interstadial mis 5a they indicate a relatively stable eemian with increasing precipitation reducing the continentality of the climate with time during the transition from the eemian to the herning stadial mean july and january temperatures decreased by 4 c and by as much as 20 c respectively temperatures remained high enough to support forests during the stadials and we infer that the reconstructed decrease of precipitation below 500 mm per year caused the extirpation of forests during these periods thus we conclude that precipitation although difficult to reconstruct is of vital importance for explaining vegetation change during the eemian and eemian early weichselian transition

the origin of sulfate mineralization and the nature of the baso4 srso4 solid solution series in the ain allega and el aguiba ore deposits northern tunisia abstract ain allega and el aguiba are among the largest barite celestite deposits attributed to the triassic period in tunisia they are located in the flysch zone on the eastern edge of the triassic diapir of jebel hamra the ore body consists of dolomite intensely brecciated and surrounded by marls clay gypsum and dolomite which forms the hanging wall of the deposit and rimmed by paleocene marls the ore minerals show a cap rock type mineralization with various forms and types in particular impregnation in dolomite breccia cement replacement of carbonate cap rock and open space filling in the dissolution cavities and fractures ore minerals include sphalerite galena marcasite and pyrite principal gangue minerals are barite celestite calcite dolomite and quartz the ore minerals are hosted by the triassic carbonate rocks which show hydrothermal alteration dissolution and brecciation the study of barite celestite solid solution shows a bimodal distribution in which the composition is not continuous some intermediate compositions are missing 20 80 srso4 for the el aguiba ore deposit and 50 70 srso4 for the ain allega ore deposit x ray diffraction peaks in the baso4 srso4 series display considerable broadening at intermediate compositions the unit cell volume varies from 346 97 a3 in barite 100 baso4 to 308 29 a3 in celestite 100 srso4 this variation in cell parameters is attributed to the degree of substitution of barium by strontium since there is less variation between ionic radii of these elements consequently these substitutions caused variation in morphologies position and d spacing of peaks 200 011 113 312 122 112 and 111 some barite crystals have small scale strontium compositional banding which suggests that the crystals responded to regular fluctuations in physiochemical conditions during deposition the degree of supersaturation in ba2 and sr2 controls the growth mechanism and consequently the surface structure which in turn controls the mechanism of adsorption and incorporation of minor and trace elements into the growing crystal for a solid solution the transitional supersaturation for different growth mechanisms can be significantly different for the two end members one of the most interesting and intriguing phenomena observed in natural crystals of the ba sr so4 solid solution from this study area is the development of compositional oscillatory zoning consisting of alternating ba rich and sr rich layers the sulfur isotope analyses show significant variability for barite and celestite from 16 2 to 23 these values are interpreted as the result of the mixing of two sulfur end members in the mineralizing fluids corresponding to thermochemical sulfate reduction of messinian seawater together with triassic sulfate as sulfur sources fluid inclusion studies of celestite show that the baso4 srso4 solid solution in both deposits was precipitated from hot saline solution th 190 20 c 16 37 wt nacl equivalent in ain allega and 8 2 wt nacl equivalent in el aguiba consequently the precipitation could be from mixing of basinal brines with magmatic meteoric fluid

the avalon terrane of newfoundland geophysical correlations from onshore to offshore as evidence for precambrian to tertiary structural evolution abstract the avalon terrane in eastern canada has a complex geological and structural history from the precambrian to the present on land the terrane is typified by faulted precambrian clastic basins bounded by arcuate belts of mafic and felsic volcanics these basins are overlain by spatially limited exposures of cambro ordovician sediments there is structural evidence of paleozoic events after the cambro ordovician including the juxtaposition of the avalon against the rest of newfoundland in devonian carboniferous times but no significant deposition offshore there are siluro devonian basins extensive areas of carboniferous deposition and the mesozoic petroliferous basins of the grand banks each having characteristic trends traditional studies of the avalon have focused on either the onshore portion or the mesozoic basins this paper presents an attempt to understand the relationship between the two using published geophysical data gravity and magnetic data were used to produce basic and derived maps to interpret the orientation of geophysical features of the terrane directional filtering techniques were used to identify and highlight particular trend orientations and directional arrow plots were used to identify the spatial distribution of trends various age events in the avalon terrane are correlated with specific geophysical trend directions the dominant arcuate and northerly directed patterns are considered to be precambrian with some hercynian reworking east west trends are probably related to the emplacement of the collector anomaly in the devonian carboniferous and to the continuation into the avalon of south armorican trends from europe the nw oriented features correlate with major transfer faults of jurassic middle cretaceous age in the mesozoic basins and can be followed to the land area providing evidence for similar aged events onshore there is also evidence for nne tertiary trends offshore the mesozoic features are closely related to the atlantic opening history the nw oriented features appear to cross the dover hermitage fault suggesting that more of newfoundland than the avalon terrane may have been affected by mesozoic events

numerical 230th u dating and a palynological review of the holsteinian hoxnian interglacial abstract earth scientists increasingly consider the holsteinian interglacial and mis 11 as synonyms despite the limited number of numerical dates and ambiguous stratigraphic and palynological correlation with the numerical marine isotope timescale hence we present new tims 230th u dates from two fen peat layers of the holsteinian reference site at bossel in northern germany and re evaluate published numerical data from two sites with hoxnian deposits in england a new method for the calculation of methodically controlled minimum 230th u ages mcma was developed the synopsis of the 230th u dates allows a correlation of both the holsteinian and hoxnian interglacials to mis 9 this correlation is supported by supplementary 230th u dates of fen peat from several pre eemian but non holsteinian sites in germany there is palynological evidence for a reliable correlation between precisely investigated and numerically dated holsteinian deposits in poland germany england sw ireland and france an apparently contradictory palynological correlation from the french central massif is discussed

tropical tales of polar ice evidence of last interglacial polar ice sheet retreat recorded by fossil reefs of the granitic seychelles islands abstract in the search for a record of eustatic sea level change on glacial interglacial timescales the seychelles ranks as one of the best places on the planet to study owing to its location with respect to the former margins of northern hemisphere ice sheets that wax and wane on orbital cycles the local or relative sea level history is predicted to lie within a few meters of the globally averaged eustatic signal during the last interglacial period we have surveyed and dated last interglacial fossil corals to ascertain peak sea level and hence infer maximum retreat of polar ice sheets during this time interval we observe a pattern of gradually rising sea level in the seychelles between 129 and 125 thousand years ago ka with peak eustatic sea level attained after 125 ka at 7 6 1 7 m higher than present after accounting for thermal expansion and loss of mountain glaciers this sea level budget would require 5 8 m of polar ice sheet contribution relative to today s volume of which only 2 m came from the greenland ice sheet this result clearly identifies the antarctic ice sheet as a significant source of melt water most likely derived from one of the unstable marine based sectors in the west and or east antarctic ice sheet furthermore the establishment of a 5 9 1 7 m eustatic sea level position by 128 6 0 8 ka would require that partial ais collapse was coincident with the onset of the sea level highstand

the east kemptville tin deposit yarmouth county nova scotia a pb isotope study of the leucogranite and mineralized greisens evidence for a 366 ma metallogenic event pb isotopic data for whole rock leucogranite and mineral separates variably mineralized greisen and galena from the east kemptville sn cu zn ag deposit yarmouth county southwestern nova scoti

new insights into the appalachian orogen from geology and geochronology along the cape ray fault zone southwest newfoundland reverse oblique overthrusting of high grade port aux basques gneiss over the lower grade supracrustal windsor point group along the cape ray fault zone occurred during late silurian to early devonian time and is attributed to major oblique collision between gondwanan and laurentian continental blocks new u pb zircon 40 ar 39 ar and k ar data limit the timing of this orogenic event the megacrystic granitic phase of the cape ray igneous complex and the cape ray tonalite have been dated at 488 3 ma and 469 2 ma respectively a black rhyolite from the windsor point group yielded an ordovician age 453 5 4 ma a pretectonic gabbro sill within the windsor point group dated at 424 4 3 ma is cut by the windowglass hill granite dated at 424 2 ma synkinematic hornblende and biotite from the grand bay complex mylonites of the port aux basques gneiss have 40 ar 39 ar ages of 407 4 ma and 403 4 ma respectively which is indicative of a late silurian early devonian age for the amphibolite grade deformation these ages are compatible with a previously determined 415 ma monazite age interpreted as the time of peak metamorphism in the port aux basques gneiss and suggests rapid exhumation the east west flexure of the cape ray fault zone represents a tear fault accommodating differential shortening between the cape ray fault zone and the correlative fault system in central newfoundland mid devonian granites 386 3 384 2 ma intervene between the thrusting events and a younger sinistral transcurrent movement this deformation and magmatic history can be correlated throughout the northern appalachians along other major fault boundaries

braidplain evolution in the pennsylvanian south bar formation sydney basin nova scotia canada abstract the south bar formation is a 1 km thick alluvial succession in the pennsylvanian morien group of the sydney basin nova scotia that fines upward from conglomerate to pebbly sandstone to sandstone facies assemblages the conglomerate assemblage comprises mainly massive to horizontally stratified conglomerate and planar cross stratified sandstone attributed to deposition in proximal braided rivers confined between bedrock ridges the sandstone assemblage shows uniformity of facies and paleocurrents across the basin and is interpreted as a distal braidplain deposit the pebbly sandstone assemblage is transitional between the other two both sandstone assemblages are dominated by trough cross stratified sandstone formed by dune migration in channel tracts about 4 m deep this succession differs markedly from platte river and icelandic sandy braidplain deposits which are mainly planar cross stratified sands formed by broad shallow flow the south bar sandstones are more like south saskatchewan river deposits but differ in 1 greater abundance of trough sets and 2 rarity of planar sets and other components of shallow water channel fill these features are ascribed to 1 inheritance of relatively deep channels from confined upstream reaches 2 maintenance of deep flow in active tracts by local confinement between temporary banks and 3 rapid avulsive abandonment of active tracts which inhibited development of channel fill sequences evidence for local temporary confinement is preserved as in situ and slumped channel margin mudrock units lateral and vertical transitions from the upper south bar formation to the mud rich waddens cove and sydney mines formations are ascribed to changes in channel pattern from braided to meandering the former is attributed to decreased slope the latter to eustatic rise in sea level

hydrography and mollusc faunas of the baltic and the white sea north sea seaway in the eemian abstract palynologically dated mollusc and cirriped faunas from a region extending from the north sea through the baltic and karelia to the arkhangelsk region show that the hydrography of the baltic was very different from the holocene for 2 2 5 ka in the early eemian a seaway existed from the barents to the north sea through karelia until it was severed at the present continental watershed to the north of lake onega after this the ladoga onega trough remained an arm of the baltic for several millennia the benthic faunas are comparable to the holocene but their boundaries were displaced much further into the baltic notable differences from the holocene are the absence or rarity of the macoma balthica biocoenosis and the presence of cold portlandia dominated biocoenoses in karelia in the belt sea and western baltic winter sea surface temperatures and salinity were higher than now by ca 6 c and 15 and the distinctly brackish top layer was missing at the same time cold bottom water 2 5 c with a tendency to anoxia characterised the karelian arm of the baltic water exchange through this area was inhibited by the constriction to the north of lake onega and the basin and threshold bathymetry water transport through the white sea baltic seaway was too sparse to play an active role in the north atlantic surface circulation or climatic change in the region the high salinity and temperature in the belt sea and western baltic persisted throughout the eemian and are explained by wider and deeper passage from the north sea to kattegat wider straits through denmark higher salinity in the north sea higher evaporation as well as more dispersed fresh water supply the advection of oceanic water into the baltic culminated in the early eemian before the carpinus zone and probably resulted in an oceanic climate in the baltic region while at the same time cold winters produced cold bottom water in the karelian arm

late paleozoic collision delamination short lived magmatism and rapid denudation in the meguma terrane nova scotia canada constraints from 40ar 39ar isotopic data the meguma terrane consists of 8 15 km of early paleozoic stratified rocks deposited on a continental basement that were deformed and metamorphosed during the late paleozoic as a result of lithospheric plate collision the oldest cleavage previously published whole rock 40ar 39ar plateau ages of 415 395 ma dates the onset of crustal thickening which was followed by voluminous but short lived late devonian granitic and minor mafic magmatism 380 370 ma this magmatism may have been the product of delamination of the lower lithosphere and upwelling of asthenosphere which effected melting above the new moho and resulted in intrusion at depths of 5 12 km 40ar 39ar plateau ages of hornblende muscovite and biotite indicate that at the present erosion level most of the meguma terrane cooled through 300 c by 368 360 ma slightly earlier than for the southwestern meguma terrane ca 345 ma the present erosion level was exhumed by the latest devonian early carboniferous visean the age of the

geochronological evidence for multiple tectono thermal overprinting events in the east kemptville muscovite topaz leucogranite yarmouth county nova scotia canada the east kemptville muscovite topaz leucogranite located in yarmouth county nova scotia canada is host rock to the only producing primary tin deposit in north america 56 mt 0 165 sn previous geochronological studies include i rb sr whole rock analyses of the quartz topaz greisens which indicated a date of 337 5 ma and ii 40ar 39ar analyses of greisen muscovite which indicated apparent plateau dates of ca 300 ma however the pervasive development of deformational fabrics at east kemptville suggests that both the rb sr whole rock and 40ar 39ar muscovite ages are at best minimum estimates for the inferred time of mineralization in the present study rb sr whole rock and mineral muscovite plagioclase k feldspar analyses and 40ar 39ar incremental step heating of a muscovite separate indicate the following i diffusion of sr on the whole rock scale terminated at 344 5 ma 11 point isochron date coincident with closure of muscovite to intracrystalline diffusion of ar apparent plat

vertical distribution of physical chemical features of water and bottom sediments in four saline lakes of the khangai mountain region western mongolia characterizing vertical profiles of water columns is important to understanding the biochemical cycles and nutrient dynamics of an aquatic ecosystem physical and chemical properties of surface water in mongolian saline lakes have been studied over the past decade but chemical composition along a vertical profile of the water column has not been well documented four major saline lakes lakes telmen oigon tsegeen and khag in northwestern mongolia were studied to determine geochemical behavior of microelements and to assess major ionic components and trace elements associated with vertical profile of various water samples and sediments water samples were vertically collected from each sampling depth with a vacuum deep water sampler in july 2013 physical chemical parameters major ionic components and trace elements were analyzed by conventional methods and inductively coupled plasma mass spectrometry concentrations of microelements and mineralogical composition of sediment samples from near shore were characterized by x ray fluorescence spectrometry and x ray diffraction this study was apparently the first to characterize chemical composition along vertical profiles of these lakes sodium chloride and sulfate ions were largely conserved in all water samples except lake oigon depending on salinity type these lakes were divided into sodium sulfate lake lake khag or chloride lakes due to geomorphological characteristics strontium 3 18 mg l was the only ion in the highest concentration across all depths of water and sediment samples among the lakes sediments were comprised mainly of quartz anorthite albite and orthoclase in conclusion physical and chemical properties in lake oigon were highly variable and dissimilar among lakes furthermore we inferred that vertical profiles of water columns were intimately linked to variations in chemical composition of salt lakes in the western mongolia

palaeoecological investigations and 230 th u dating of the eemian interglacial peat sequence from neubrandenburg hinterste muhle mecklenburg western pomerania ne germany abstract the eemian interglacial sequence was explored in the gravel pit neubrandenburg hinterste muhle near neubrandenburg ne germany the sequence is situated in a former kettle hole depression between underlying late saalian till s str warthe covered by a late weichselian till today still visible a 3 m long and max 2 m wide profile is located on the edge of the former eemian depression the limnic sedimentation began during the late saalian in a landscape characterized by open herbaceous vegetation cool clear and calcium carbonate rich lake water dominated inhabited by characeae that indicates a presence of stonewort meadows most typical of waters up to 10 m in depth the beginning of the eemian interglacial succession was characterized by a dominance of scarce birch forest followed by pine forest the beginning of the mesocratic phase of the eemian was characterized by the appearance of warm climate indicators and by the development of thermophilic forest communities dominated by oak forest with the appearance of warm climate indicators the ensuing climate optimum was defined by the encroachment of hazel oak forest and later by mixed deciduous forest limnic sedimentation ceased in the basin during this phase and the end of predominantly limnic conditions is marked by a decrease in the frequency of aquatic plants and an increase in the amount of brown mosses during the interglacial optimum mixed forests reigned this phase bears a record of oligotrophication leading to transition mire and raised bog and the aquatic plants vanished the depression gradually became shallower and was overgrown by a forest cover during the telocratic phase of the eemian communities with pine birch and fir spread the end of the interglacial was characterized by a disappearance of the riparian forest and a sporadic appearance of reedswamp plants at the beginning of the early weichselian a deterioration of climatic conditions resulted in the formation of widespread heaths on acid soils and trees disappeared in the studied basin the water level fluctuated the hinterste muhle sequence shows the development of a small kettle hole lake and its transformation to an overgrowing mire including terrestrialization processes during the eemian interglacial the u th data obtained for five samples from the upper part of the studied profile which have been analyzed by the tsd technique has yielded an age of 116 13 10 kyr this date reflects the classification into the second half of the eemian interglacial and the early weichselian for the upper part of peat formation

40ar 39ar dating of hydrothermal biotite from high grade gold ore tangier gold deposit nova scotia further evidence for 370 ma gold metallogeny in the meguma terrane a hydrothermal biotite carbonate alteration zone adjacent to a high grade multi ounce gold vein in the tangier gold deposit meguma terrane nova scotia has given an 40 ar 39 ar plateau age of 374 ma the alteration halo is part of a vein package in the hinge zone of the tangier anticline which contains abundant auriferous quartz veins formed during flexural slip folding during a late stage reactivation of the regional fold belt the 374 ma age is similar to 40 ar 39 ar ages determined for hydrothermal vein minerals at seven other meguma gold districts thereby suggesting a terrane wide metallogenic event a similar age of vein formation and by inference gold mineralization and granite emplacement across the meguma terrane suggest that the cospatial and cotemporal nature of the two geological events may be related an integrated model including anatexis and devolitization of the lower crust possibly as a consequence of overriding a mantle plume in concert with late stage reactivation of the fold belt owing to continued transpression along a terrane bounding fault is proposed

last interglacial eemian hydrographic conditions in the southeastern baltic sea ne europe based on dinoflagellate cysts abstract a rich organic walled dinoflagellate cyst and pollen record from the licze borehole in northern poland has been used to reconstruct the hydrographic history of the southeastern baltic sea during the last interglacial eemian stage late pleistocene warm saline waters ca 10 15 psu entered the site from the north sea within the first few hundred years of the eemian corresponding to the pinus betula e1 or pinus betula ulmus e2 regional pollen assemblage zones rpaz by about 300 years beginning of rpaz e3 dinoflagellate cyst assemblages were already indicating summer sea surface salinities in excess of about 15 psu and temperatures that perhaps exceeded 27 c warm and saline conditions of 15 20 psu or more at least twice present levels persisted throughout the early eemian a rise in sea level at licze appears to correlate with a similar event in eastern denmark as both coincide with the increase in corylus ca 750 years into the interglacial this sea level rise might therefore have a basinwide extent and appears to correspond to an opening of the danish belts there is little if any evidence of arctic waters throughout the sequence whereas dinoflagellate cysts reflect sustained high salinites within the upper water column a concomitant increase in abundance of the chlorococcalean alga pediastrum within the carpinus corylus alnus e5 rpaz indicates an escalating freshwater input presumably from the proto vistula whose mouth was nearby this suggests the development of a thin seasonal low salinity surface layer below which dinoflagellates lived in more saline waters increasing fluvial influence suggests shallowing through rpaz e5 this study is the first to document dinoflagellate cysts from the eemian of the southeastern baltic sea and reveals a flora with distinctive lusitanian mediterranean affinities

new 40ar 39ar ages from the kalatag district in the eastern tianshan nw china constraints on the timing of cu mineralization and stratigraphy abstract the kalatag region in the eastern tianshan of nw china contains a number of economically important cu deposits among these the south meiling vms deposit is hosted in the late ordovician to early silurian dacitic tuff belonging to the daliugou formation the deposit is composed of two domains a concordant massive sulfide ore domain and a discordant vein type ore domain located in the footwall phyllic alteration zone here we report new 40 ar 39 ar ages on sericite from the phyllic alteration zone to better constrain the timing and genesis of mineralization the sericite displays markedly flat 40 ar 39 ar age spectra yielding a 40 ar 39 ar plateau age of 438 8 3 0 ma and an isochron age of 443 0 11 0 ma the 40 ar 39 ar age is in good agreement with the re os age reported earlier placing the timing of cu zn mineralization at 434 2 3 9 ma the age is also consistent with the field relationships that concordant massive sulfide orebody formed later than discordant vein type orebody another deposit at hongshi is hosted in basaltic andesites of the daliugou formation the orebodies cut the phyllic alteration zone indicating that the cu mineralization formed later than the phyllic alteration hydrothermal sericite from the phyllic alteration zone from this deposit yielded flat 40 ar 39 ar age spectra with 40 ar 39 ar plateau ages of 441 5 3 2 ma and 446 4 4 6 ma and isochron ages of 445 8 5 6 ma and 448 8 7 3 ma respectively this age is obviously older than the re os age which is also in conformity with the field relations that quartz sulfide veins cut the sericitization zone our 40 ar 39 ar ages offer precise constraints on early paleozoic cu mineralization in the eastern tianshan orogen these results indicate that the lower unit basaltic andesites of the daliugou formation formed earlier than 446 ma we thus consider that the daliugou formation formed during middle ordovician to early silurian we also propose several metallogenic events in the kalatag area including 1 an early vms cu zn and hydrothermal vein cu mineralization at 440 430 ma 2 porphyry cu and skarn fe mineralization at 390 380 ma and 3 a late cu au mineralization at ca 300 ma these three metallogenic events were coeval with the distinct magmatic pulses in the kalatag area

last interglacial climates the last interglacial commonly understood as an interval with climate as warm or warmer than today is represented by marine isotope stage mis 5e which is a proxy record of low global ice volume and high sea level it is arbitrarily dated to begin at approximately 130 000 yr b p and end at 116 000 yr b p with the onset of the early glacial unit mis 5d the age of the stage is determined by correlation to uranium thorium dates of raised coral reefs the most detailed proxy record of interglacial climate is found in the vostok ice core where the temperature reached current levels 132 000 yr ago and continued rising for another two millennia approximately 127 000 yr ago the eemian mixed forests were established in europe they developed through a characteristic succession of tree species probably surviving well into the early glacial stage in southern parts of europe after ca 115 000 yr ago open vegetation replaced forests in northwestern europe and the proportion of conifers increased significantly farther south air temperature at vostok dropped sharply pulses of cold water affected the northern north atlantic already in late mis 5e but the central north atlantic remained warm throughout most of mis 5d model results show that the sea surface in the eastern tropical pacific warmed when the ice grew and sea level dropped the essentially interglacial conditions in southwestern europe remained unaffected by ice buildup until late mis 5d when the forests disappeared abruptly and cold water invaded the central north atlantic ca 107 000 yr ago

post paleocene cooling in the southern canadian atlantic region evidence from apatite fission track models the traditional view of the geomorphic evolution of the southern canadian atlantic margin is one of gradual exhumation and peneplanation following triassic jurassic rifting thermal modelling of apatite fission track data from pre carboniferous granitic basement in nova scotia and from permian and triassic sandstones from nova scotia new brunswick and prince edward island suggest a more complex thermal evolution of the onshore part of the margin models clearly indicate significantly elevated regional paleotemperatures during jurassic time and as much as 30 c of post paleocene cooling model predicted paleogeothermal gradients for granitic samples from the digby d 1 well are normal ranging from 15 to 20 c km post paleocene cooling may be attributable to the combined effects of 13 c of exhumational cooling from erosion of approximately 700 m of post aptian sediments caused by decreased eustatic sea levels and 8 17 c of cooling from the propagation to depth of a 10 20 c decrease in paleo mean ann

geochemical evolution of uraniferous soda lakes in eastern mongolia extremely high concentrations of uranium u were discovered in shallow groundwater fed hyperalkaline soda lakes in eastern mongolia a representative groundwater sample in this area is dilute and alkaline ph 7 9 with 10 mm tic and 5 mm cl in contrast a representative lake water sample is ph 10 with tic and cl each more than 1 000 mm groundwater concentrations of u range from 0 03 to 0 43 m l 1 lake water u ranges from 0 24 to 62 5 m possibly the highest naturally occurring u concentrations ever reported in surface water strontium isotopes 87sr 86sr varied in groundwaters from 0 706192 to 0 709776 and in lakes 87sr 86sr varied from 0 708702 to 0 709432 high concentrations of u na cl and k correlate to radiogenic sr in lake waters suggesting that u is sourced from local cretaceous alkaline rhyolites uranium rich groundwaters are concentrated by evaporation and u vi is chelated by co 3 2 to form the highly soluble uo2 co3 3 4 modeled evaporation of lakes suggests that a u mineral phase is likely to precipitate during evaporation

thermochronologic constraints on ore formation at the gays river pb zn deposit nova scotia canada from apatite fission track analysis fission tracks in detrital apatites from the cambro ordovician metasedimentary basement in the vicinity of the carboniferous hosted gays river pb zn deposit nova scotia provide a record of final

geologic fluid inclusion and stable isotope studies of the gays river lead zinc deposit nova scotia canada the gays river deposit is the largest carbonate hosted lead zinc deposit known in the mississippian windsor group of atlantic canada the orebody mainly occupies one flank of a porous dolomitized carbonate bank that unconformably overlies a basement ridge of the metasedimentary lower paleozoic megurea group the orebody consists of stratiform disseminated sulfides as open space fillings in primary and secondary pores of the dolomite and fault controlled veinlike bodies of high grade massive sphalerite and galena the carbonate bank is overlain by evaporite deposits of mississippian age underground mapping and laboratory studies suggest four main stages of evolution for gays river 1 deposition of the visean carbonate bank preore evaporite deposition pervasive dolomitization and growth of diagenetic marcasite 2 deposition of sphalerite galena chalcopyrite and calcite as a result of influx of hydrothermal metal rich saline brines into fractures and porous dolomite 3 postore deposition of calcite fluorite barite marcasite pyrite and selenite and 4 uplift localized dedolomitization of the mineralized carbonates and exposure by erosion in cretaceous times microthermometry of fluid inclusions yields the following mean homogenization temperatures sphalerite 215oc ore stage calcite 173oc postore calcite 142oc fluorite 142oc and barite 137oc pressure corrections should be minimal for these temperatures no evidence of boiling was observed in the inclusions salinity determinations from the ice melting temperatures of inclusions in postore fluorite and calcite yield a value of ca 20 4 equivalent wt percent naci for the hydrothermal fluid during the waning stages of mineralization isotopic analyses indicate that anhydrite and gypsum in the overlying evaporites and barite within the orebody are enriched in heavy sulfur t 34s 13 1 16 5 0 suggesting a mississippian seawater source ore stage sphalerite galena and chalcopyrite probably derived their sulfur b34s 8 0 13 65 0 from sulfates or possibly a homogenized basement source postore marcasite and pyrite are characterized by light probably biogenic sulfur ba4s 9 7 to 46 0 mineralized carbonates are significantly depleted in the heavier isotopes of oxygen and carbon with respect to their unmineralized equivalents preliminary lead isotope data for galena suggest that the metasedimentary basement was a source of lead this study disputes an earlier interpretation that the stratiform lead zinc ores are an early low temperature diagenetic cement of the carbonate bank the high grade zones are not residual concentrations related to sinkholes as originally thought instead both disseminated and massive ores are probably the result of the same mineralizing episode involving deeply convecting brines or brines expelled during basin dewatering under high geothermal gradients in the late paleozoic

late paleozoic to cenozoic history of the offshore sydney basin atlantic canada the sydney basin covers a large offshore area south of newfoundland with a well exposed outcrop belt on cape breton island the geological history of the poorly known offshore area is interpreted using an industry seismic grid and lithoprobe line 86 5 tied to outcrops and two wells the mid devonian to upper carboniferous permian basin fill is 6 7 km thick and represents three extensional phases with intervening and succeeding compressive phases the mid devonian mcadams lake formation was deposited in a local half graben during early post acadian extension following deformation a suite of early carboniferous extensional basins filled mainly with horton group conglomerates developed on northeast trending and southeast dipping master faults some faults developed along acadian terrane boundaries the windsor group extends over the master faults to onlap basement as a result of thermal sag and visean eustatic rise mid carboniferous deformation linked to the alleghanian orogeny reactivated faults an

polyphase late paleozoic tectonothermal evolution of the southwestern meguma terrane nova scotia evidence from 40ar 39ar mineral ages 40ar 39ar incremental release ages of hornblende muscovite and biotite from a variety of granitic stocks and host metamorphic rocks suggest a complex late paleozoic tectonothermal evolution for the southwestern meguma terrane regional d1 folding with cleavage formation under greenschist lower amphibolite facies m1 metamorphic conditions occurred at ca 400 410 ma and was followed by emplacement of a series of granitic stocks ranging in age between ca 375 and 315 ma these were emplaced at relatively shallow crustal levels and developed contact metamorphic aureoles of variable grade these are locally superposed on m1 regional metamorphic assemblages and result in a complex isograd pattern 40ar 39ar mineral ages suggest episodes of contact metamorphism occurred at 1 360 375 ma possibly related to emplacement of the south mountain batholith or temporal equivalents 2 350 356 ma around the port mouton pluton and northeastern shelburne pluton 3 ca 315 325 ma near the wedgeport pluton and in

vegetation and climate changes during the eemian and early weichselian in the upper volga region russia abstract ples is the key section that represents the mikulino eemian interglaciation and early part of the valdai weichselian glacial epoch in the north central russia pollen profile of this section reflects spread of the broad leaved forest dominated by quercus ulmus and tilia with participation of acer fraxinus and carpinus in the optimum phase of the interglaciation a gradual cooling and increasing humidity of climate brought about a decline in the broad leaved forest and development of dark coniferous communities picea abies pinus sibirica in the end of the interglaciation it was followed by scots pine and birch forest and then replaced by communities of tundra shrubs with patches of the open birch forest during the first post eemian cooling the climatic conditions were not uniform as a short climatic amelioration separated it into two stages this minor warming is indicated by an increase in birch woodland in complex plant cover this first early weichselian cold stage was followed by a warm interstade when mixed spruce birch and later larch pine and spruce pine forests occupied the region this interstade known as verkhnevolzhskiy upper volga in the climatostratigraphic subdivision of the late pleistocene in the russian plain after grichuk 1961 fossil floras as the basis for the quaternary stratigraphy in markov k k ed rel ef i stratigrafiya chetvertichnykh otlozheniy severo zapada russkoi ravniny izdatel stvo an sssr moscow pp 25 71 corresponds to the brorup interstade in the northern europe or to marine oxygen isotope substage mis 5c e g mangerud 1989 correlation of the eemian and the weichselian with deep sea oxygen isotope stratigraphy quaternary international 3 1 4 on the whole we correlate the sediment sequence at ples to the mis from 5e to 5c

deformation of upper carboniferous coal measures in the sydney basin evidence for late alleghanian tectonism in atlantic canada upper carboniferous stephanian coal measures of the sydney basin are deformed by reverse faults and folds with dips of up to 50 on the limbs these structures represent compressional or transpressional events donkin episode of unknown sequence and timing offshore swath bathymetry data indicate that northwest striking reverse faults are folded by prominent northeast trending folds vitrinite reflectance patterns of oriented coal samples from the fold limbs are uniaxial negative with minimum reflectance axes rmin near normal to bedding and fanning across fold axes this pattern implies that the bulk of coalification took place through burial compaction without directed horizontal stress prior to the deformation that produced the folds slight divergence between rmin axes and poles to bedding may reflect slight tilting associated with differential subsidence or early reverse faulting before or during coalification or may lie within analytical error one moderately biaxial sample suggests that some deformation accompanied coalification locally available apatite fission track data for the sydney basin indicate that cooling of the coal measures to below 100 20 c was underway by the middle to late triassic or earlier because cooling implies that coalification was largely complete the fission track results are compatible with latest paleozoic or early mesozoic deformation we infer that the donkin episode represents late alleghanian permian compression within the appalachian orogen if so the sydney structures are manifestations of a little known tectonic episode in atlantic canada however mesozoic cenozoic deformation cannot be ruled out resume les series houilleres du bassin de sydney carbonifere superieur stephanien sont deformees par des failles inverses et des plis deverses dont les flancs atteignent des pendages de 50o ces structures representent des evenements de compression ou de transpression episode donkin dont la sequence et la synchronisation sont inconnues les donnees de bathymetrie par secteurs au large indiquent que les failles inverses a direction nord ouest sont pliees par des plis proeminents a tendance nord est les patrons du facteur de reflexion de la vitrinite provenant d echantillons de charbon orientes preleves sur les flancs des plis sont uniaxes negatifs avec des axes de reflectance minimum rmin presque perpendiculaires au litage et se dispersant en travers des axes de plis ce patron implique que la plus grande part de la carbonisation a eu lieu par compaction d enfouissement sans contrainte horizontale directe avant la deformation qui a produit les plis la legere divergence entre les axes rmin et les poles du litage pourrait refleter un leger basculement associe a une subsidence differentielle ou a des failles inverses precoces avant ou durant la carbonisation ou encore cette divergence pourrait etre a l interieur de la fourchette de l erreur analytique notre echantillon moderement biaxe suggere qu une certaine deformation ait localement accompagne la carbonisation pour le bassin de sydney les donnees disponibles de datation par traces de fission sur l apatite indiquent que le refroidissement des series houilleres a des temperatures inferieures a 100 20 oc etait deja en cours au trias moyen a tardif ou plus tot puisque le refroidissement implique que la carbonisation etait presque terminee les resultats de datation par traces de fission concordent avec la deformation au paleozoique terminal ou au mesozoique precoce nous concluons que l episode donkin represente une compression a l alleghanien tardif permien a l interieur de l orogene des appalaches si tel est le cas les structures de sydney sont des evidences d un episode tectonique peu connu au canada atlantique cependant une deformation au mesozoique cenozoique ne peut etre rejetee d emblee

sedimentological processes in lahars insights from optically stimulated luminescence analysis abstract a lahar is a sediment laden flow capable of major destructive impacts on infrastructure and human life how lahars transport sediment is thus a key issue for understanding lahar sedimentology and behavior especially in terms of the lahar s hydraulic and rheological properties which can be substantially altered as the lahar gains or loses material during its travel in this research we analyze lahar entrainment processes by evaluating luminescence signals total photon counts from lahar sediments using blue luminescence signals blsl a portable osl reader that analyzes several grams of polymineral and polygrain size samples was applied we use data from three lahars in the tenenepanco and huiloac gorges on popocatepetl volcano mexico to elucidate the ways in which lahars may gain lose and transport sediment during flow sediment samples for luminescence analysis were taken through the full thickness of the lahar deposits at eight different sites for two lahars 1997 and 2001 and at one site for a lahar that occurred 500 yrs ago mean luminescence values obtained for the 1997 lahar help to evaluate the relationship between the lahar entrainment processes and the drainage at the different sites for the 2001 lahar this relationship was also established taking into account the channel slope the main conclusion is that luminescence signals total photon counts can be used to detect entrained material in the flow because the bulked materials modify the final osl signals the application of this type of luminescence analysis thus has the potential to provide a better understanding of sediment entrainment in these sediment laden flows

the terrestrial eemian to late weichselian sediment record at beckentin ne germany first results from lithostratigraphic palynological and geochronological analyses abstract over recent decades a growing number of well documented records from terrestrial last interglacial sites across central europe have substantially improved our understanding of eemian climate and landscape dynamics despite this progress there are also large areas from which little information is available thus constituting significant paleo geographic gaps in the last interglacial record among the regions with still inadequate paleo environmental information is the maritime influenced area of ne germany at the southern margin of the eemian baltic sea here we present first results from a geological investigation of a new last interglacial site recently discovered during archaeological excavations near beckentin sw mecklenburg the study area is located approximately 25 km to the south of the maximum mis 2 ice limit of the scandinavian ice sheet in ne germany and thus lies outside the weichselian belt of glaciation based on lithostratigraphic and sedimentological logging complemented by geochemical xrf and palynological investigations we divide the local succession into three sections 1 a basal facies comprising saalian till and associated glaciofluvial sand overlain by section 2 consisting of a fen peat which grades into laminated organic to minerogenic mud the organic deposits of section 2 preserve a near complete eemian pollen inventory encompassing pollen zones pz i to vi menke and tynni 1984 above this rest poorly sorted periglacial sands section 3 with ventifacts and evidence for cryogenic deformation geochronological results from 230th u dating of the buried organic rich deposits at beckentin show that these units accumulated in a former dead ice depression between 118 7 6 ka and 114 6 5 ka during the eemian interglacial high resolution optically stimulated luminescence osl profiling undertaken with a portable luminescence reader reveals a significant hiatus between the lacustrine fines and overlying periglacial cover sand five osl ages obtained from these cover sediments and the sand filling of an ice wedge cast show that these strata formed between during the last glacial interglacial transition

late devonian lamprophyric dykes in the meguma zone of nova scotia hornblende rich lamprophyric dykes from southeastern nova scotia are contemporaneous with the large peraluminous granitic batholiths ca 370 ma of the meguma zone and may be closely associated with their origin

a multivariate approach to geochemical distinction between tin specialized and uranium specialized granites of southern nova scotia like most granitoid bodies that host significant granophile deposits the south mountain batholith smb of nova scotia consists of an earlier suite intruded by a later suite of smaller plutons that are more silicic and peraluminous the latter generally show a range of other geochemical features that readily identify them as specialized and allow for their separation from the earlier non specialized granites in the case of mineralization associated with the smb we can go one step further and clearly separate the specialized granites into stanniferous and uraniferous series which can be identified even where no sn or u enrichment is present although this can be done successfully using simple histograms of a number of elements li p sn and f we show that combining all elements in discriminant analysis guarantees 100 success in separating the two groups r mode factor analysis aids in accounting for the variance within each group the most important effect being a biotite factor because of bo

characteristics of ree and other trace elements in response to successive and superimposed metasomatism within a portion of the south mountain batholith nova scotia canada abstract successive and superimposed periods of late to post magmatic metasomatism have resulted in mineralogical and textural modification within leuco monzogranitic rocks of the big indian lake polyphase intrusive suite bipis the alteration and associated mineralization exhibit a transition from an early pervasive style to a later fracture controlled style and can be defined by diagnostic ree and other trace element behavior while the anomalous behavior of some elements mno ta u k rb hree is attributed to metasomatic hydrothermal activity the compatible behavior of b f li w and rb appears to have been governed by predominately magmatic processes all elements including al can be mobilized during repeated fluid rock interaction the behavior of ree during evolution of the bipis indicates that they also were affected by both magmatic lree depletion eu depletion and metasomatic hree lree enrichment eu enrichment depletion processes the remobilization and subsequent redeposition of trace elements is dependent upon the nature and stability of the metasomatic mineral assemblages in this respect a metasomatized granitic rock could reflect a ree pattern similar to that of an unaltered equivalent

the analysis of last interglacial mis 5e relative sea level indicators reconstructing sea level in a warmer world the last interglacial mis 5e 128 116 ka is among the most studied past periods in earth s history the climate at that time was warmer than today primarily due to different orbital conditions with smaller ice sheets and higher sea level field evidence for mis 5e sea level was reported from thousands of sites but often paleo shorelines were measured with low accuracy techniques and in some cases there are contrasting interpretations about paleo sea level reconstructions for this reason large uncertainties still surround both the maximum sea level attained as well as the pattern of sea level change throughout mis 5e such uncertainties are exacerbated by the lack of a uniform approach to measuring and interpreting the geological evidence of paleo sea levels in this review we discuss the characteristics of mis 5e field observations and we set the basis for a standardized approach to mis 5e paleo sea level reconstructions that is already successfully applied in holocene sea level research application of the standard definitions and methodologies described in this paper will enhance our ability to compare data from different research groups and different areas in order to gain deeper insights into mis 5e sea level changes improving estimates of last interglacial sea level is in turn a key to understanding the behavior of ice sheets in a warmer world

sequence of events from the onset to the demise of the last interglacial evaluating strengths and limitations of chronologies used in climatic archives the last interglacial lig represents an invaluable case study to investigate the response of components of the earth system to global warming however the scarcity of absolute age constraints in most archives leads to extensive use of various stratigraphic alignments to different reference chronologies this feature sets limitations to the accuracy of the stratigraphic assignment of the climatic sequence of events across the globe during the lig here we review the strengths and limitations of the methods that are commonly used to date or develop chronologies in various climatic archives for the time span 140 100 ka encompassing the penultimate deglaciation the lig and the glacial inception climatic hypotheses underlying record alignment strategies and the interpretation of tracers are explicitly described quantitative estimates of the associated absolute and relative age uncertainties are provided recommendations are subsequently formulated on how best to define absolute and relative chronologies future climato stratigraphic alignments should provide 1 a clear statement of climate hypotheses involved 2 a detailed understanding of environmental parameters controlling selected tracers and 3 a careful evaluation of the synchronicity of aligned paleoclimatic records we underscore the need to 1 systematically report quantitative estimates of relative and absolute age uncertainties 2 assess the coherence of chronologies when comparing different records and 3 integrate these uncertainties in paleoclimatic interpretations and comparisons with climate simulations finally we provide a sequence of major climatic events with associated age uncertainties for the period 140 105 ka which should serve as a new benchmark to disentangle mechanisms of the earth system s response to orbital forcing and evaluate transient climate simulations

extreme variations in strontium initial ratios in ore related fluids magmato hydrothermal cassiterite topaz ore at the carboniferous east kemptville ek greisenhosted tin deposit nova scotia canada is cross cut by veins containing apatite triplite vivianite and fluorite initial 87sr 86sr ratios of these minerals have an extreme range 0 7135 to 0 8284 the initial ratios of the host rocks ek quartz topaz rock and davis lake biotite monzogranite 0 729 0 001 0 727 0 004 are also high the adjacent meguma group metasedimentary rocks are more typical of crustal material 0 712 0 719 at 330 ma rb and sr contents of ek fluorite max 13 0 1420 ppm and apatite max 88 1 6660 ppm are unusually high and variable unexpectedly high sr contents correlate positively with the high initial 87sr 86sr ratios fluorite and phosphate minerals from the first set of post greisen veins at east kemptville reflect the unusual chemistry of a high 87sr 86sr fluid present in the deposit after ore formation the most extreme composition of this fluid was characterized by 87sr 86sr 0 8284 high rb sr high p rb cu zn and fe contents but low abundances of ca pb and sn with respect to the davis lake monzogranite such a fluid could have been derived from the greisen fluid and modified by reaction with the overlying meguma metawacke a second alternative which cannot be well constrained at present is that an extremely radiogenic fluid entered the deposit after ore formation and mixed with the postore fluid in either case the modified fluid subsequently mixed with meteoric water and precipitated the minerals with much lower 87sr 86sr ratios and rb and sr contents