the interrelation of glaciotectonic and glaciodepositional processes within the glacial environment abstract in recent years it has been recognised that ice sediment coupling occurred beneath the quaternary ice sheets that advanced over the soft sediments of lowland areas this paper looks in detail at the effects of this coupling on the sediments which results in glaciotectonic deformation and also discusses the interaction of deformation and deposition within the subglacial environment two types of glaciotectonic deformation are discussed that are produced by the active movement of ice 1 proglacial tectonics at the margin which include compressive fold styles such as listric thrusts and faults and open folding 2 subglacial tectonics formed beneath the glacier which include fold styles resulting from simple shear and represent a soft rock purely dynamic shear zone styles of deformation associated with stagnant ice are also investigated we argue that glaciotectonic deformation is a common phenomenon and an integral part of geological record from continental ice sheets it is suggested that zones of deformation within the sediment are related to similar zones of strain in the ice sheet and complex deformation sequences are produced by the superimposition of these differing styles upon one another as the ice sheet advances and retreats it is also argued that subglacial deposition and deformation are related and that on soft beds underformed till is rare whilst deformed till is very common

estimation of rock physics properties from seismic attributes part 2 applications abstractthe estimation of quantitative rock physics properties is of great importance for reservoir characterization and monitoring in co2 storage or enhanced oil recovery as an example we have combined the high resolution results of full waveform inversion fwi methods with rock physics inversion because we consider a generic and dynamic rock physics model our method is applicable to most kinds of rocks for a wide range of frequencies the first step allows determination of viscoelastic effective properties i e quantitative seismic attributes whereas the rock physics inversion estimates rock physics properties porosity solid frame moduli fluid phase properties or saturation this two step workflow is applied to time lapse synthetic and field cases the sensitivity tests that we had previously carried out showed that it can be crucial to use multiparameter inputs to accurately recover fluid saturations and fluid properties however due to the limited data availability and difficulties in get

osl and tl dating of buried podsols and overlying sands in ostrobothnia western finland in ostrobothnia western finland buried fossil soils have been recognised in a number of places in the sandy sediments that occur between glaciofluvial deposits and overlying till samples from the soil horizons as well as below and above them were taken for optically stimulated luminescence osl dating the same sites were also sampled for thermoluminescence tl dating altogether five tl dates and seventeen osl dates were obtained the osl dates can be grouped into two age classes i 120 163 ka and ii 76 106 ka whereas all tl dates are of the order 135 155 ka a comparison between the results obtained from the two dating methods shows that osl dates are generally younger than the tl dates for the same sample the discrepancy may arise partly from problems of setting a correct residual level in tl dating if this is the case then the tl dates may indicate an upper limit for the true age the results support the geological interpretation that the fossil soils were formed during the last interglacial that the soil forming processes possibly also continued during the first early weichselian stadial and interstadial brorup sensu lato and that in general the till covered glaciofluvial sequences interpreted as eskers in ostrobothnia were deposited during the saalian or early weichselian deglaciation

the last interglacial glacial cycle in ne fennoscandia a nearly continuous record from sokli finnish lapland abstract boreholes from the sokli basin in finnish lapland have recovered a unique sequence of diamicts interlayered with fine grained sediments that are rich in fossils the diamicts are interpreted as till beds deposited by the fennoscandian ice sheet the fine grained intercalations seem to represent a series of warm stages that include one interglacial and three interstadials the interglacial is characterized by a mixed taiga pollen assemblage and corresponds to a distinct diatom gyttja bed the interstadials show progressively colder floras from open birch forest to arctic forest limit to shrub tundra their sediments comprise gyttja interlayered with wood and sand interstadial 1 sands grading into sandy gyttja interstadial 2 and sands overlain by laminated silt and clay interstadial 3 the interstadial 2 and 3 deposits are underlain by diamict and are interpreted as deglaciation sequences silts with a tundra pollen assemblage separate the interglacial and interstadial 1 deposits luminescence dating evidence indicates that the interglacial bed most probably represents the nw european mainland eemian interglacial marine isotope stage mis 5e the interstadial 1 2 and 3 deposits are tentatively correlated with the early weichselian brorup and odderade interstadials and an interstadial of middle weichselian age respectively mis 5c 5a and 3 respectively the correlation implies that the easternmost part of the ice divide zone of the fennoscandian continental ice sheet was deglaciated during part of mis 3

four dimensional seismology and true direct detection of hydrocarbons the petrophysical basis figure 1 published by m king hubbert in 1962 and again in 1969 shows the exploitation of fossil fuels in a historical perspective according to this graph about half of the fossil energy on earth is being used up in a period of about 200 years half of which is by now over

postglacial land uplift patterns of south sweden and the baltic sea region comparison of the land uplift pattern for the last 10 300 years shown by studies of raised shorelines of the baltic ice lake with the pattern of present day land uplift of fennoscandia shows that significant regional changes of uplift pattern have taken place some of these changes seem to be related to a halt in ice retreat during the younger dryas cold stage it is also probable that some observed anomalies in the present uplift are not of glacio isostatic origin but are possibly related to structures in the lower lithosphere and upper mantle or large scale tectonics

biostratigraphy of the last glacial period in europe the european early weichselian early wurmian is characterized by two long and relatively warm interstadials brorup and odderade which can be traced and correlated with certainty across large parts of europe the amersfoort interstadial described earlier from the netherlands has been included in the brorup and represents the older part of it both great interstadials were forested in north west central and southern europe in the north conifer forests prevailed giving way towards the south to deciduous forests the climatic gradient was distinctly steeper mainly due to southward displacement of the gulf stream the two great interstadials are synchronous with the isotopic stages 5a and 5c in the deep sea cores subsequent to eemian brorup and odderade and from within the context of a continuous series two additional and clearly delimited interstadials have been recorded in a new standard profile from oerel nw germany these are now described as the oerel and glinde interstadials they were not forested and belong to the early pleni weichselian the lower one oerel can probably be correlated with the 3rd weichselian wurmian interstadial in southern central europe ognon ii durnten samerberg 3 while the upper one glinde has so far no known counterpart for the younger pleni glacial it is assumed that there was a long phase during which it was not too cold the formation of humic layers during this phase took place at different times partly due to local edaphic factors so that the relevant 14c dates show a wide scatter the hengelo and denekamp interstadials represent only slight ameliorations which facilitated the formation of shrub tundra and can be recorded in certain regions only

quantitative estimates of pedogenic ferromagnetic mineral formation in chinese loess and palaeoclimatic implications abstract the quasi continuously deposited loess sediments of the central chinese loess plateau constitute one of the most complete and long lasting records of quaternary palaeoclimate on land much of this record has been uncovered by measurement and interpretation of the magnetic properties of the loess the polarity of natural remanent magnetization has provided absolute age dates by correlation with the geomagnetic polarity time scale magnetic low field susceptibility has been used to reconstruct the cyclic changes of pleistocene palaeoclimates although the origin of the signal is still poorly understood from comparison with the 10 be concentration throughout the sequence we are able to determine the contributions to susceptibility from inherited and authigenic sources for the last 130 ky since the production of authigenic magnetite is directly related to regional precipitation annual palaeoprecipitation rates can be calculated palaeoprecipitation rates similar to present day rates are derived for oxygen isotope stage 5 including the last interglacial in contrast cold periods corresponding to oxygen isotope stages 2 and 4 experienced negligible precipitation the beginning and end of the time interval represented by oxygen isotope stage 3 however was characterized by short episodes when precipitation exceeded the holocene average

fluctuations of the svalbard barents sea ice sheet during the last 150 000 years abstract on spitsbergen western svalbard three major glacial advances have been identified during the weichselian all three reached the continental shelf west of the svalbard archipelago radiocarbon luminescence and amino acid dating of interbedded interstadial and interglacial sediments indicate that these glacial advances have early isotope stage 5d middle stage 4 and late weichselian ages stage 2 an additional more local advance has been dated to isotope stage 5b the late weichselian ice sheet expanded across the entire barents sea however in the south western barents sea the late weichselian till is the only till above eemian sediments indicating that the early and middle weichselian ice advances were restricted to the svalbard archipelago and the northern barents sea a major problem with the onshore sites is the dating of events beyond the range of the radiocarbon method to overcome this the onshore record has been correlated with marine cores from the continental slope and the deep sea west of svalbard where a chronology has been established by oxygen isotope stratigraphy ice rafted detritus ird was used as the main monitor of glaciation the ird record closely mirrors the glaciation history as interpreted from the onshore sections during the late weichselian the largest ird peak occurred during deglaciation a pattern also postulated for the earlier events given this the results from the marine cores indicate that the ages for the first glacial advances during the weichselian were a few thousand years older than interpreted from the onshore stratigraphy

the extent of the barents kara ice sheet during the last glacial maximum it has been a long standing discussion whether the barents kara ice sheet expanded onto mainland russia during the last glacial maximum lgm in this paper we describe many well dated by conventional and ams 14 c methods and optically stimulated luminescence sedimentary sequences in the controversial area of northern russia the sequences discussed are not covered by till and yet all predate the lgm the deposits consist mostly of aeolian or lacustrine easily deformable soft silt and fine sand two sites feature frozen mammoth carcasses and three sites contain palaeolithic artefacts and mammalian bones we emphasise that these formations show no sign of having been overridden by an ice sheet at several sites deposition of aeolian sediments and formation of ice wedges took place during the lgm time span these observations present unambiguous proof that the barents kara ice sheet did not cover mainland russia during lgm with a possible exception for the northern tip of the taimyr peninsula r 2001 elsevier science ltd all rights reserved

palaeolithic landscapes of europe and environs 150 000 25 000 years ago an overview abstract when considering the evolution and migrations of neandertalers and early modem human beings the harsh conditions of the last glacial maximum are often implicitly or explicitly assumed as their environmental background this perception is false the conditions of the high glacial apply to a small fraction of late pleistocene time here we review the palaeoenvironmental history of europe from 150 000 to 25 000 years ago with the aid of data from long cores of ice and marine and continental sediments the results are displayed in four sketch maps that illustrate the landscapes of an interglacial glacial cycle the maps connected by palaeoenvironmental histories show that especially between 60 000 and 25 000 years ago a critical part of the palaeolithic the glacial landscapes were for much of the time less barren than is generally assumed but numerous climate changes on a scale of several millennia are evident placing a premium on accurate dating of the co evolution of humans and landscape moreover during the glacial interval abrupt climatic changes lasting from a century to a few millennia were common their importance for landscape changes and their impact on human activity remain to be ascertained

stability of the seaward slope of berm breakwaters abstract an extensive research on stability of statically and dynamically stable rock slopes and gravel beaches was reanalysed and focussed on berm breakwaters berm breakwaters are initially dynamically stable under severe wave attack but become more or less statically stable after reshaping the effects on the seaward profile of wave height period storm duration spectral shape initial slope rock size rock shape and grading water depth and angle of wave attack are described in a qualitative way relationships between these variables and the profile parameters are described leading to a computer program this program was verified with independent data of berm breakwaters from various international institutes the program showed to give a good prediction of the behaviour of the seaward slope of berm breakwaters and can therefore be used as a conceptual design tool

formal stratigraphy of the neopleistocene middle and upper late pleistocene in the kola region nw russia abstract this paper presents available litho chrono biostratigraphy data on sediment sequences in the kola region derived from russian publications based on this compilation key sections have been suggested for primary stratigraphic subdivisions or horizons according to the general quaternary stratigraphic chart of russia the regional quaternary scheme is correlated with the international chart summarizing the available data 10 geological sections have been proposed as key sites sections for the middle and upper late neopleistocene horizons in different sections in the southern kola peninsula the most ancient deposits correspond to the chekalinsky early saalian mis 9 horizon which is identified by esr dating and multi proxy data and also to the moskovsky late saalian mis 6 horizon specified according to litostratigraphic data the last interglacial glacial cycle relates to the mikulinsky entire mis 5 podporozhsky mis 4 leningradsky mis 3 and ostashkovsky mis 2 horizons two marine events identified in key sections on the coastal kola peninsula correspond to the last interglacial mikulinsky mis 5 horizon they are referred to as the ponoi and strelna beds in the regional stratigraphic classification the third marine unit is correlated to the interstadial leningradsky mis 3 horizon key sections in the central and western kola region provide the interglacial and interstadial terrestrial sequences there is a high probability that litho biostratigraphy data and a single numerical ir osl dating testify to the glacial podporozhsky mis 4 horizon deposits in coastal natural outcrops and boreholes in the lovozero tundra mountains key sections of the ostashkovsky mis 2 horizon have not been referred to in the formal kola region stratigraphy yet

implications for the late pleistocene climate in finland and adjacent areas from the isotopic composition of mammoth skeletal remains nine samples of subfossil bone and teeth remains from woolly mammoth mammuthus primigenius discovered in finland russian karelia and western russia were analyzed for the oxygen isotope composition of the phosphate fraction and the carbon and oxygen isotope composition of the carbonate fraction in skeletal apatite the samples have been radiocarbon dated in previous studies and are of late middle weichselian to late weichselian age the preservation of the samples was tested analyzing the chemical composition and checking the isotopic equilibrium between the phosphate and carbonate components in skeletal apatite according to these tests five out of the nine samples were determined to have retained their original isotopic composition these samples were used to estimate late pleistocene climatic conditions in finland and neighboring areas based on the best preserved enamel samples the isotopic composition of oxygen in late pleistocene precipitation was 1 3x lower than that in the mean annual precipitation in southern and central finland today using the relationship between the isotopic composition of precipitation and the ambient temperature it can be estimated that the mean temperatures during the middle weichselian ice free period were 2 6 8c lower compared to the present day values d 2005 elsevier b v all rights reserved

a new formula for front slope recession of berm breakwaters the front slope stability of breakwaters with a homogeneous berm was studied in a large number of two dimensional model tests at aalborg university denmark the results are presented together with a new formula for prediction of the berm recession which is the most important parameter for describing the reshaping the formula has also been calibrated and validated against model test data from other researchers the significance of the new design formula is that it predicts berm recession much better than the existing methods especially in case of more stable structures

middle pleistocene marine deposits on the kola peninsula nw russia abstract a unique middle to late pleistocene site is situated in the southern part of the kola peninsula on the right bank of the lower varzuga river providing for the first time valuable evidence concerning middle pleistocene climate change and a marine transgression event during this period the corresponding strata are exposed in a 2 km long natural outcrop traceable along the abrupt slope of the river valley where the fluvial erosion and slumping have dissected a remnant elongated hill middle pleistocene marine deposits compose here the basal part of the sedimentary succession lithological sedimentological and structural field study accompanied by esr dating of mollusc shells taken from marine sediments and a detailed palynological investigation have been carried out the basal part of the varzuga section is represented by superposition of consolidated clay loam sandy loam with subfossil mollusc shells and small lenses of coarse grained sand and pebbles unit 1 marine shells were esr dated between 319 0 38 5 ka and 316 0 23 6 ka glacial diamicton and glacifluvial sands unit 2 probably also middle pleistocene in age overlay the marine sediment with sharp contact the uppermost part of the sequence consists of the late pleistocene marine sediments glacial diamicton glacifluvial sand and presumably late glacial and early holocene lacustrine deposits one hundred samples of marine unit 1 and lowermost part of glacial unit 2 deposits were palynologically reinvestigated on the basis of detailed palynostratigraphy 19 pollen assemblage zones were identified recurring vegetative assemblages characterized by increasing quantity of betula with occurrence of mesophilous and thermophilous components alnus quercus tilia ulmus carpinus corylus osmunda nuphar nymphaea indicate five middle pleistocene warm events mostly during marine isotope stage mis 9

ice dammed lakes and rerouting of the drainage of northern eurasia during the last glaciation during the quaternary period ice sheets centred over the barents and kara seas expanded several times onto mainland russia and blocked northflowing rivers such as the yenissei ob pechora and mezen large ice dammed lakes with reversed outlets e g toward the caspian sea formed south of these ice sheets some lakes are reconstructed from shorelines and lacustrine sediments others mainly from ice sheet configuration ice dammed lakes considerably larger than any lake on earth today are reconstructed for the periods 90 80 and 60 50 ka the ages are based on numerous optically stimulated luminescence osl dates during the global last glacial maximum lgm about 20 ka the barents kara ice sheet was too small to block these eastern rivers although in contrast to the 90 80 and 60 50 ka maxima the scandinavian ice sheet grew large enough to divert rivers and meltwater across the drainage divide from the baltic basin to the river volga and that way to the caspian sea climate modelling shows that the lakes caused lower summer temperatures on the continent and on the lower parts of the ice sheet the final drainage of the best mapped lake is modelled and it is concluded that it probably emptied within few months we predict that this catastrophic outburst had considerable impact on sea ice formation in the arctic ocean and on the climate of a much larger area c 2003 elsevier ltd all rights reserved less

early mis 3 glacial lake evolution ice marginal retreat pattern and climate at sokli northeastern fennoscandia lake development at sokli northern finland is traced through the analysis of diatoms and other siliceous micro fossils in a 2 meter thick minerogenic laminated clay silt deposit dated to the early part of marine isotope stage mis 3 fluctuating water levels and changes in lake extent depicted by the siliceous micro fossil record together with lithology suggest that an important part of the sediment sequence was deposited in a glacial lake the proxy based glacial lake evolution is tested using a digital elevation model and geomorphologic evidence including eskers dated to the early mis 3 tulppio interstadial at sokli despite the apparent ice dammed nature of the lake the sediment is relatively rich in fossils and there are limited signs of re deposition of older fossil material the siliceous micro fossil record together with data from other proxies previously analysed in the same sediment samples provides a coherent picture of past environmental changes around the sokli site this is most probably due to the sheltered position of the coring site in a lake embayment quantitative climate reconstructions based on the diatom record show mean july air temperatures as high as present day values at sokli and the temperature ranges indicated by the diatom record are in agreement with temperature reconstructions based on chironomids the position of sokli in the northeastern portion of the central area of the scandinavian glaciations and the northern retreat pattern implies that an important part of eastern fennoscandia was deglaciated during the early mis 3 warming event

uncertainties in quantitative time lapse seismic analysis most seismic time lapse studies so far have been of a qualitative nature identification of areas with minor or no seismic changes has been used to plan new infill drilling targets increased accuracy in seismic acquisition methods in both conventional streamer surveys and newer methods such as multicomponent sea bed seismic and permanent sensors opens possibilities for the next step quantitative time lapse analysis quantitative methods here mean the estimation of for instance a change in fluid saturation from 20 water to 90 water or the estimation of a pore pressure change of 5 mpa explicit expressions for the uncertainties associated with estimated changes in for instance reservoir pressure and fluid saturation are derived these formulae can be used to compare relative uncertainties between estimated parameters as well as to identify the critical factors in various estimation techniques the importance of accurate rock physics input as well as that of highly repeatable time lapse seismic data is emphasized furthermore uncertainty analysis can be used to find optimal weight factors when the same parameter e g saturation change is estimated by two or three different techniques

discrimination between pressure and fluid saturation changes from marine multicomponent time lapse seismic data discrimination between pressure and fluid saturation changes from marine multicomponent time lapse seismic data

diagnostic characteristics and paleodynamics of supraglacial rock avalanches innerdalen western norway abstract misinterpretation of rock avalanche deposits in mountain environments is not uncommon because of the complex interactions between rock avalanches and glaciers this paper for the first time presents a detailed description of suspicious rock boulder deposits which are remnants of a rock avalanche onto a late pleistocene glacier the boulder deposits cover around 1 1 km 2 and are distributed over an area of around 7 5 km 2 and a variety of landforms three closely nested distinct terminal moraines 0 45 km 2 and dislocated terminal moraines 0 34 km 2 entirely built up of large boulders lateral moraines that decrease in elevation over a short distance and connect to the terminal moraines small patches 0 02 km 2 of boulders that occur in islands on a peat dominated valley floor and large patches of boulder fields 0 25 km 2 in size hanging 350 m above the valley floor the latter are disconnected from any potential source area 10 be cosmogenic nuclide ages of the three terminal moraines give an indistinguishable late pleistocene age of 13 6 1 4 ka whereas the largest boulder field that is located on the opposite side of the valley from the failed mountain yields a 10 be age of 14 1 0 4 ka which is slightly older but indistinguishable from the moraine deposits within uncertainty margins all boulder deposits add up to a volume of 31 10 6 m 3 the interpretation of a single rock avalanche source for those landforms is further confirmed by numerical runout modeling using dan3d a failure of the entire volume from skarfjellet mountain would result in a runout pattern that is identical to that of the distributed boulder fields when considering that the valley was filled with a glacier around 350 m thick the rock avalanche would not reach the position of the terminal moraines however a glacial re advance could have transported the boulders to that position the late pleistocene rock avalanche was followed by a holocene rock avalanche with a volume of 23 10 6 m 3 and a typical lobate deposit damming the innerdalen valley and creating a lake 10 be ages indicate that this event occurred 7 97 0 94 ka ago structural measurements performed on high resolution lidar scans show a strongly jointed source rock with three joint sets with dip dip direction 81 034 86 331 and 77 354 and a foliation with 22 003 the kinematic of the failures can thus be a combination of small scale wedge failures and planar sliding on shallow dipping foliation our detailed description can enable a better identification and interpretation of similar deposits in other mountain areas

discrimination between pressure and fluid saturation changes from time lapse seismic data explicit expressions for computing saturation and pressure related changes from time lapse seismic data have been derived and tested on a real time lapse seismic data set necessary input is near and far offset stacks for the baseline seismic survey and the repeat survey the method has been tested successfully in a segment where pressure measurements in two wells verify a pore pressure increase of 5 to 6 mpa between the baseline survey and the monitor survey estimated pressure changes using the proposed relationships fit very well with observations between the baseline and monitor seismic surveys 27 of the estimated recoverable hydrocarbon reserves were produced from this segment the estimated saturation changes also agree well with observed changes apart from some areas in the water zone that are mapped as being exposed to saturation changes which is unlikely saturation changes in other segments close to the original oil water contact and the top reservoir interface are also estimated and conf

upper pleistocene and holocene stratigraphy in the kola peninsula and northern karelia n w russia marine and glacial units abstract data on litho and biostratigraphy of major sedimentary sequences and their geochronological records were compiled and summarized to describe the late pleistocene holocene marine and glacial events in the kola northern karelia region in the coastal kola peninsula and its inner part three marine units and two glacial events were identified in the upper pleistocene sequences the first marine unit ponoi beds in the regional stratigraphy can be definitely referred to the significant late pleistocene transgression known as the boreal in northern eurasia data on the kola peninsula show that the warm water boreal transgression was longer than the eemian one in western europe comprising at least mis 5e d from 130 120 to 105 100 ka bp in the white sea depression and mis 5e c earlier at least 90 ka bp in the barents sea forested environments dominated on the kola peninsula at that time the second interglacial marine unit strelna beds attributed to the subsequent belomorian transgression was deposited in relatively cold settings at the final phase of the mikulinian interglacial mis 5 about 100 to 70 80 ka bp adjacent areas were covered with open forest and tundra the third marine unit referred to the interstadial leningrad group was formed 60 40 ka bp in rather a cold marine reservoir when the environmental conditions were more severe than now the late pleistocene glacial events are correlated to the podporozhie and ostashkov groups mis 4 and 2 the podporozhian glacial unit seems to be associated with the barents kara ice sheet and its melting caused the glacioeustatic transgression in the white sea during the leningradian substage mis 3 during the late glacial and holocene a periglacial freshwater lake brackish water basin and marine reservoir successively appeared in the white sea depression successively two marine events are suggested here based on the key sedimentary sequences from the coastal isolated lake i e the late glacial transgression and the early middle holocene tapes transgression

correlation of the eemian and the weichselian with deep sea oxygen isotope stratigraphy abstract the eemian interglacial was defined in the netherlands and is correlated all over northern europe it is now demonstrated that the eemian was the last interglacial in europe thus it is obvious that it should correlate with either the entire stage 5 in the deep sea oxygen isotope stratigraphy or with parts of stage 5 several observations prove that the eemian correlates with substage 5e the two other peaks in stage 5 correlates with the warm interstadials brorup and odderade in northern europe

vp vs ratio versus differential stress and rock consolidation a comparison between rock models and time lapse avo data the compressional to shear wave velocity ratio vp vs is an important parameter in seismic amplitude versus offset avo analysis and this parameter plays a key role especially for lithology and fluid prediction methods the p wave velocity is a key parameter in traditional pressure prediction methods because overpressure often results in a velocity reduction however for avo based pore pressure prediction methods one expects that the vp vs ratio also is a key parameter the hertz mindlin geomechanical model predicts a constant vp vs ratio as the differential stress changes in a dry package of identical spheres ultrasonic core measurements show increased vp vs ratios as the differential stress decreases especially for unconsolidated wet sands thus one is likely to assume that the vp vs ratio is dependent on rock consolidation by combining the hertz mindlin model with the gassmann model we show how to obtain a sim ple rock physics framework including both the differential stress and

acoustic measurements in unconsolidated sands at low effective pressure and overpressure detection shallow water flows and over pressured zones are a major hazard in deepwater drilling projects their detection prior to drilling would save millions of dollars in lost drilling costs i have investigated the sensitivity of seismic methods for this purpose using p wave information alone can be ambiguous because a drop in p wave velocity vp can be caused both by overpressure and by presence of gas the ratio of p wave velocity to s wave velocity vp vs which increases with overpressure and decreases with gas saturation can help differentiate between the two cases since p wave velocity in a suspension is slightly below that of the suspending fluid and vs 0 vp vs and poisson s ratio must increase exponentially as a load bearing sediment approaches a state of suspension on the other hand presence of gas will also decrease vp but vs will remain unaffected and vp vs will decrease analyses of ultrasonic p and s wave velocities in sands show that the vp vs ratio especially at low effective pressures

evaluation of scale effects in hydraulic models by analysis of laminar and turbulent flows abstract the paper presents an analysis of laminar and turbulent flow in porous stone material in order to evaluate the order of magnitude of scale effects in hydraulic models hydraulic model tests such as for example breakwater model tests are normally carried out at such small scales that the flow through the various layers of the breakwater is not completely turbulent for this reason scale effects occur a well known method to compensate for the scale effects is to use larger stones than calculated by froude s model law in certain regions of the model the paper presents formulae for the calculation of the compensated stone sizes based on earlier work by engelund further an evaluation of the energy dissipation in hydraulic models is made in order to determine the scale effect due to laminar flow

late quaternary ice sheet history of northern eurasia the maximum limits of the eurasian ice sheets during four glaciations have been reconstructed 1 the late saalian 140 ka 2 the early weichselian 100 80 ka 3 the middle weichselian 60 50 ka and 4 the late weichselian 25 15 ka the reconstructed ice limits are based on satellite data and aerial photographs combined with geological field investigations in russia and siberia and with marine seismic and sediment core data the barents kara ice sheet got progressively smaller during each glaciation whereas the dimensions of the scandinavian ice sheet increased during the last ice age the barents kara ice sheet attained its maximum size as early as 90 80 000 years ago when the ice front reached far onto the continent a regrowth of the ice sheets occurred during the early middle weichselian culminating about 60 50 000 years ago during the late weichselian the barents kara ice sheet did not reach the mainland east of the kanin peninsula with the exception of the nw fringe of taimyr a numerical ice sheet model forced by global sea level and solar changes was run through the full weichselian glacial cycle the modeling results are roughly compatible with the geological record of ice growth but the model underpredicts the glaciations in the eurasian arctic during the early and middle weichselian one reason for this is that the climate in the eurasian arctic was not as dry then as during the late weichselian glacial maximum

an experimental study on the hydraulic stability of icelandic type berm breakwaters abstract one of the key aspects of breakwater design and safety assessment is their stability evaluation in the present paper hydraulic stability of a multi layer berm breakwater mlbb has been studied through varying the parameter of eroded area to this end a 2 d experimental model has been carried out in the wave flume of tarbiat modares university using irregular waves with a jonswap spectrum a total of 150 tests have been performed to cover a wide range of sea state conditions and geometrical parameters such as wave height wave period water depth berm width berm elevation stone class i height front slope and nominal diameter of stone class i in this study a new dimensionless parameter is introduced to indicate that the wave breaking type plays a fundamental role in stability of mlbbs eventually a new formula is derived to estimate the damage of mlbbs based on different sea state conditions and various geometrical parameters comparisons are made between the estimated damage parameter of mlbbs by the proposed formula and those estimated by existing formulae the results denote that the present formula not only performs well for mlbbs experimental data but also indicates a reliable performance for some of lykke andersen s 2006 data in statically homogenous berm breakwaters hbbs outside the range of given formula furthermore an innovative approach is presented to examine the eroded area based on the berm recession and the intersection point of reshaped and initial profile from swl which performs faultlessly rather than the existing one

estimation of changes in saturation and pressure from 4d seismic avo and time shift analysis a reliable estimate of reservoir pressure and fluid saturation changes from time lapse seismic data is difficult to obtain existing methods generally suffer from leakage between the estimated parameters we propose a new method using different combinations of time lapse seismic attributes based on four equations two expressing changes in prestack avo attributes zero offset and gradient reflectivities and two expressing poststack time shifts of compressional and shear waves as functions of production induced changes in fluid properties the effect of using different approximations of these equations was tested on a realistic synthetic reservoir where seismic data have been simulated during the 30 year lifetime of a water flooded oil reservoir results found the importance of the porosity in the inversion with a clear attenuation of the porosity imprint on the final estimates in case the porosity field or the vertically averaged porosity field is known a priori the use of a first order approximation of the gradient reflectivity equation leads to severely biased estimates of changes in saturation and leakage between the two different parameters both the bias and the leakage can be reduced if not eliminated by including higher order terms in the description of the gradient or by replacing the gradient equation with p and or s wave time shift data the final estimates are relatively robust to random noise as they present fairly high accuracy in the presence of white noise with a standard deviation of 15 the introduction of systematic noise decreases the inversion accuracy more severely

extent and dynamics of the scandinavian ice sheet during oxygen isotope stage 3 65 000 25 000 yr b p the climate of the middle weichselian glaciation marine oxygen isotope stage 3 ois 3 a relatively mild period compared to the glacial maxima of ois 4 and ois 2 consisted of long warm interstades punctuated by brief cold excursions that grew colder and more frequent with time the ois 4 ice sheet is generally thought to have persisted throughout ois 3 but evidence from dated ois 3 interstadial deposits suggests that it was swiftly reduced to small remnants which only briefly expanded and retreated only 30 000 years ago the deteriorating climate initiated a sustained ice advance leading toward the final glacial maximum of ois 2 dynamic ice sheet models support the existence of a prolonged ice free interval during ois 3 induced perhaps by low precipitation due to extensive sea ice cover offshore

quaternary glaciations in southern fennoscandia evidence from southwestern norway and the northern north sea region abstract based on records from the northern north sea and southern norway quaternary fennoscandian glaciations are described and discussed maximum glaciation defined as the presence of shelf edge glaciation an ice stream flowing out of the norwegian channel and most likely an ice divide over the central part of fennoscandia sweden gulf of bothnia occurred for the first time in the late cenozoic at ca 1 1 myr the fedje glaciation this glaciation was followed by a ca 600 kyr period with at least two glaciations with ice extension somewhat larger than the younger dryas event in the region the first maximum glaciation of the bruhnes chron was during isotope stage 12 and was followed by repeated maximum glaciations within each of the light isotopic stages until stage 2 during the weichselian the southwestern part of the fennoscandian ice sheet reached maximum position three times sometime between 22 and 28 37 and 50 and 60 and 80 ka limited glaciations probably occurred during stadials between the early and middle weichselian interstadials between 500 ka and 1 1 myr and most likely also prior to 1 1 myr deep norwegian sea ice rafted detritus ird records reflecting contributions from several different ice sheets fennoscandian barents sea iceland and greenland each with large variations in history of ice extent to their respective margins yet to some degree they reflect the glaciation of the northern north sea region with an increasing ird input around 1 1 myr and a relatively low input of north sea components during some cycles around the b m boundary maximum glaciations occurred during insolation minima in the earlier part of the middle pleistocene however not all such minima are reflected by maximum glaciation in southern parts of fennoscandia the relatively poor chronological control and non continuous character of the data on weichselian interstadials stadials precludes a clear relationship to atmospheric changes recorded in greenland ice cores as well as to precession and or obliquity cycles in insolation

armor stability of hardly or partly reshaping berm breakwaters abstract this paper deals with stability of hardly or partly reshaping berm breakwaters a simple physical argument is used to derive a new stability formula based on the assumption that the maximum wave force causing damage of armor layer is proportional to the maximum wave momentum flux near the structure toe the main goal of the present paper is to provide an estimation technique based on this physical principle to predict the deformation of the front slope in terms of the eroded area the proposed method is verified by comparison with model test data it is found that by using the maximum wave momentum flux approach the damage to the front slope eroded area can be very well predicted moreover a simple method to estimate the eroded area based on measured or calculated berm recession rec and depth of intersection of reshaped and initial profile h f is presented the performance of the simple method based on measured data of rec and h f is better than the presented stability equation based on wave momentum flux parameter when using the best prediction formulae for recession and depth of intersection the simple method and the momentum flux stability equation provide similar uncertainty

weighted stacking for rock property estimation and detection of gas amplitude versus offset concepts can be used to generate weighted stacking schemes here called geo stack which can be used in an otherwise standard seismic data processing sequence to display information about rock properties the zoeppritz equations can be simplified and several different approximations appear in the literature they describe the variation of p wave reflection coefficients with the angle of incidence of a p wave as a function of the p wave velocities the s wave velocities and the densities above and below an interface using a smooth representative interval velocity model from boreholes or velocity analyses and assuming no dip the angle of incidence can be found as a function of time and offset by iterative ray tracing in particular the angle of incidence can be computed for each sample in a normal moveout corrected cmp gather the approximated zoeppritz equation can then be fitted to the amplitudes of all the traces at each time sample of the gather and certain rock properties can be estimated the estimation of the rock properties is achieved by the application of time and offset variant weights to the data samples before stacking the properties which can be displayed by geo stack are p wave reflectivity or true zero offset reflectivity s wave reflectivity and the reflectivity of p wave velocity divided by s wave velocity or pseudo poisson s ratio reflectivity if assumptions are made about the relation between p wave velocity and s wave velocity for water bearing clastic silicate rocks then it is possible to create a display which highlights the presence of gas

estimation of net to gross from p and s impedance in deepwater turbidites the limitations of using low frequency 3 d seismic data for detailed reservoir characterization are well recognized nonetheless these data are very well suited for quantitative estimates of the net to gross n g which is a reservoir scale property critical in deepwater turbidite reservoir characterization and development projects the acoustic impedance inversion of 3 d seismic has been routinely used with varying success to estimate n g in many clastic reservoirs indeed when the shale baseline impedance can be estimated the departure from this trend can be argued to represent a certain measure of the hydrocarbon saturated sand volume on the reservoir scale we take this technique a step further by using both acoustic and shear impedance ai and si and applying them to horn mountain deepwater reservoirs gulf of mexico gom where six appraisal wells were available for calibration

rock lithology and porosity determination from shear and compressional wave velocity data examined in this study are previously published laboratory shear s and compressional p wave velocity measurements on water saturated sandstone calcareous sandstone dolomite and limestone cores as well as laboratory porosity measurements on the sandstone and limestone cores sandstone and limestone porosities range from 092 to 299 and from 006 to 229 respectively differential pressure was varied from 500 to 6000 psi corresponding to approximate burial depths from 290 to 3460 m respectively sandstone limestone and dolomite are effectively separated by poisson s ratio or equivalently by the ratio of p to s wave velocity separation of sandstone and limestone appears to result from the difference in of the matrix material namely quartz 056 and calcite 316 respectively an empirical function 1 v a b was fit by regression analysis to sandstone and limestone velocity vs and vp versus porosity values at each differential pressure in this equation a and b are const

an experimental study on the parameterization of reshaped seaward profile of berm breakwaters abstract berm breakwaters are rubble mound structures in which the seaward slope of the initial profile may be reshaped to become more stable under severe wave attack the stones in the seaward slope move from the initial slope to an equilibrium profile a 2d experimental study has been carried out in a wave flume at a hydraulic laboratory of tarbiat modares university to study the effects of sea state and structural parameters on the reshaped profile parameters of such breakwaters a series of 287 tests have been performed to cover the effect of various sea state conditions such as wave height wave period number of waves and water depth at the toe of the structure and structural parameters such as berm width berm elevation above still water level and armor stone size all the tests have been done employing irregular waves with a jonswap spectrum in this paper first the reshaped profiles are schematized and then the key parameters of the reshaped seaward profiles such as step height step length and depth of intersection point of initial and reshaped profile are investigated using results of this experimental work eventually formulae that include some sea state and structural parameters are derived for estimation of the reshaped profile parameters to assess the validity of the proposed formulae comparisons are made between the estimated parameters of reshaped profiles by these formulae and earlier formulae given by other researchers the comparisons show that the estimation procedure foretells reshaping parameters well and with less scatter according to the present data and also other experimental results within the range of parameters tested

pressure induced forces and shear stresses on rubble mound breakwater armour layers in regular waves abstract this paper presents the results from an experimental investigation of the pressure induced forces in the core material below the main armour layer and shear stresses on the armour layer for a porous breakwater structure two parallel experiments were performed which both involved pore pressure measurements in the core material 1 core material with an idealized armour layer made out of spherical objects that also allowed for detailed velocity measurements between and above the armour and 2 core material with real rock armour stones the same core material was applied through the entire structure i e no additional filter layers were applied for both experiments high speed video recordings were synchronised with the pressure measurements for a detailed investigation of the coupling between the run up and run down flow processes and the measured pressure variations outward directed pressure gradients were found which exerted a lift force up to 60 of the submerged weight of the core material these maximum outward directed pressure gradients were linked to the maximum run down event and were in general situated at or slightly below the maximum run down level detailed velocity and turbulence measurements showed that the large outward directed pressure gradients in general coincide both in time and space with the maximum bed shear stresses on the armour layer based on the reynolds stresses the bed shear stresses were found to result in a shields parameter in the same order of magnitude as the critical value for movement of the armour stones

new ways of studying ice sheet flow directions and glacial erosion by computer modelling examples from fennoscandia a computer ice sheet model has been used to study regional ice flow directions and glacial erosion of the weichselian ice sheet adopting a new method of presenting modelled ice flow directions ice sheet model results from different time periods during the weichselian were extracted for five regions and presented in rose diagrams when comparing these computer generated results with information on flow directions obtained from current conceptual geological models based on field data large similarities were observed in comparing the ice flow directions as such the similarities were strikingly good in many cases there was also a good agreement in the timing of the events while in some cases a certain flow direction was assigned to a different time period by the ice sheet model than in the current interpretation of geological information nevertheless the overall agreement between the data sets shows that results from ice sheet models can aid in placing geological information into a coarse timeframe and chronostratigraphic context and also fill in time gaps in the glacial geological record where chronological control is sparse ice sheet model results thus constitute a new data set against which glacial geological information can be compared and tested a new quantity basal sliding distance has also been calculated from the ice sheet model results describing the over time accumulated length of ice that has passed over the landscape by basal sliding the results show high basal sliding distance values in sw sweden se norway in skagerrak and along the gulf of bothnia implying relatively large amounts of glacial erosion in these regions on elevated parts of the scandinavian mountain range and on adjacent plains in the east the basal sliding distance values are low implying weaker glacial erosion this compares well with different types of geological and morphological data suggesting that basal sliding distance is a useful entity for studying regional patterns of glacial erosion intensity

rock physics modeling of unconsolidated sands accounting for nonuniform contacts and heterogeneous stress fields in the effective media approximation with applications to hydrocarbon exploration by treating contact stiffness as a variable one can extend the effective medium approximation used to obtain elastic stiffness of a random pack of spherical grains more specifically we suggest calibrating effective media approximation based on contact mechanics by incorporating nonuniform contact models the simple extension of the theory provides a better fit for many laboratory and field experiments and can provide insight into the micromechanical bonds associated with unconsolidated sediments this approach is motivated by repeated observations of shear wave measurements in unconsolidated sands where observed shear wave velocities are lower than predicted by the hertz mindlin contact theory we present the calibration process for well log data from a north sea well penetrating a shallow gas discovery and a deepwater well in the gulf of mexico finally we demonstrate the benefit of using this model for amplitude variation with angle ava analysis of shallow sand targets in exploration and reservoir studies

initiation of the last glaciation in northern europe abstract the bio and chronostratigraphy of the eemian interglacial marine isotope substage 5e and an early weichselian glaciation 5d a established from representative and detailed sequences can be correlated with the deep sea oxygen isotope stratigraphy ice core data sea level fluctuations and coupled ice sheet climate models biostratigraphic sequences from fennoscandian key sections are correlated with reference sequences from estonia and from sections located near or beyond the margins of the last glaciation organic sediments previously attributed to early and middle weichselian interstadial periods in finland are argued to be redeposited and mixed older last interglacial material pollen and diatom spectra of the undisturbed materials suggest that the eemian climatic optimum was followed by a continuously cooling climate and a regressive marine level if only undisturbed sequences are considered the major climatic fluctuations of the early weichselian apparent in central and western europe are not apparent in the sequences from the central part of the glaciated terrain instead some sequences are truncated by sediments indicating approaching ice sheets soon after the interglacial this may imply that the ice sheet grew over finland during the first early weichselian stadial the preservation of the interglacial beds and the lack of younger non glacial sediments support the interpretation that the area remained ice covered until the final deglaciation during the early weichselian the norwegian coast was probably occasionally ice free similar to the coastal zone of greenland today the authors interpretation of the fennoscandian organic deposits of the last glaciation may also explain similar observations from the central parts of the laurentide ice sheet

lithostratigraphy and age estimations of the pleistocene erosional remnants near the centre of the scandinavian glaciations in western finland abstract extensive 20 100 m thick quaternary sediment accumulations deposited before the latest weichselian stage were discovered in the suupohja region in western finland near the centre of the scandinavian glaciations fourteen lithofacies have been identified and interpreted in the accumulations geomorphologically and lithostratigraphically these accumulations occur in two forms 1 till covered beaded gravelly ridges that have occasional fine grained sediments and paleosols between the gravel and the overlying till and 2 irregularly shaped broad multilayer accumulations that include up to seven till units three silt clay units and three sand units these sediments have been deposited in glacial glaciofluvial glaciomarine lacustrine and possibly in littoral and eolian environments during up to six glacial deglacial cycles the units are divided into five formations which are proposed to form the suupohja group according to the luminescence datings lithostratigraphy and sedimentary structures the sediments below the uppermost till are interpreted to have been deposited before the latest weichselian glaciation which occurred during the middle or late weichselian substage this article clarifies the multiple lithostratigraphy of the suupohja region and introduces potential type sections for further stratigraphic studies the rich diversity of the sediments and their large extent makes this region one of the key areas in the pleistocene research of the glaciated areas of northern europe

eustatic sea level and climate changes over the last 600 ka as derived from mollusc based esr chronostratigraphy and pollen evidence in northern eurasia we reconstruct and correlate palaeoclimatic events and deposits from shelf glacial periglacial and extraglacial zones of northern eurasia over the last 600 000 years the chronostratigraphical correlation of identified palaeoenvironmental and sealevel events and corresponding horizons is based on electron spin resonance esr analysis of subfossil mollusc skeletal remains from marine freshwater and acheulian bearing cave site deposits over 230 shell samples from more than 40 sites along the continental margin of eurasian north in the black and caspian sea basins and terrestrial shells from a lower palaeolithic cavesite in the northern caucasus were dated via esr to produce a late quaternary geochronology the pleistocene composite section of the loess palaeosoil formation includes two reference sections likhvin and arapovichi from the centre of the easteuropean plain the palyno chronostratigraphic record is interpreted as the product of six warm climate high sea level events including the current interglacial and six glacial events they are presented either as complete climatic rhythms of glacial and interglacial rank or by considerable portions of climatic phytocoenotic phases constituents of the rhythm the full interglacial conditions are centred at about 580 400 310 220 and between 145 70 calendar ka a broad correspondence between long palynological sequence directly esr dated warm climate related events and other palaeoenvironmental records described in the literature has been noted for 11 upper oxygen isotope stages 11 to 1 the results obtained in this study exemplify the potential of integrated chrono climatostratigraphic sequences in linking marine and terrestrial palaeoclimate records that may eventually span the whole brunhes chron d 2002 elsevier science b v all rights reserved

initiation and development of the laurentide and cordilleran ice sheets following the last interglaciation abstract fossil records from sites overridden by or adjacent to the laurentide ice sheet indicate that the climate of the last interglaciation oxygen isotope substage 5e ca 130 116 ka was warmer than today following the last interglaciation the laurentide ice sheet first developed during stage 5 over keewatin quebec and baffin island along its northern margin the ice sheet reached its maximum extent of the last glaciation during stage 5 the ice sheet advanced across baffin island onto the continental shelf early during stage 5 5d whereas the advance into the western canadian arctic occurred late during stage 5 5b the ice sheet also may have advanced into the st lawrence lowland during substage 5b although this event may be younger stage 4 the hudson bay lowland became ice free during substage 5a retreat of the ice sheet on baffin island occurred during late stage 5 probably substage 5a the exact timing of retreat from the western canadian arctic is unknown but it occurred before 48 ka the southern sector including the st lawrence lowland was ice free during late stage 5 the hudson bay lowland may have remained ice free through stage 4 and much of stage 3 because of conflicting chronologies however it is more likely that this area was glaciated throughout stage 3 and perhaps stage 4 nevertheless the data demonstrate that the lowland was ice free during part of the last glaciation an independent ice cap developed over the appalachian uplands and advanced across nova scotia during stage 4 perhaps as far as the edge of the continental shelf the ice cap remained active over nova scotia as a setellite to the laurentide ice sheet throughout the remainder of the last glaciation the ice sheet advanced into the st lawrence lowland during stage 4 and subsequently overwhelmed the local ice cap in the appalachian uplands advancing perhaps into northern new england but not farther south the lowland remained covered by the ice sheet until late stage 2 the ice sheet may also have advanced into the lake ontario basin during stage 4 the position of the northern margin of the laurentide ice sheet during stage 4 is not known but it remained an unknown distance behind its maximum position reached during stage 5 cores from baffin bay indicate a substantial decrease in high latitude glaciation during stage 4 following retreat the keewatin sector of the ice sheet may have remained over much of northwestern canada as a quasi stable ice mass until it readvanced during stage 2 similarly the baffin island sector of the ice sheet may have remained largely intact the southern margin of the ice sheet may have advanced into the lake ontario basin and upper mississippi valley during the middle of stage 3 ca 50 ka reaching its maximum extent of the last glaciation during stage 2 ca 18 21 ka advance of the northern margin was younger ca 8 13 ka than that of the southern margin this advance was less extensive than the penultimate advance stage 5 paleoenvironmental records indicate that the last interglaciation in areas covered by and near the cordilleran ice sheet was as warm as or warmer than present the cordilleran ice sheet appears to have developed during stage 5 or 4 at that time it advanced over southern british columbia and into the northern puget lowland there is no record of this event in northern areas that were later covered by the ice sheet the ice sheet disappeared before 59 ka at the beginning of a lengthy nonglacial interval paleoenvironmental records indicate that climate was similar to the present during part of this interval the ice sheet was absent and glaciers probably were confined to mountain areas throughout stage 3 climatic deterioration marking the end of this nonglacial interval may have begun as early as 29 ka by 14 15 ka the ice sheet had achieved its maximum extent of the last glaciation because there are few suitable dating methods capable of resolving events beyond the radiocarbon limit and because sites that preserve a record of events from the last glaciation are spatially restricted we consider this synthesis as tentative and subject to significant revision as dating methods improve nevertheless this perspective of the north american ice sheets through the last glaciation demonstrates their complex and dynamic behavior and attendant rapid fluctuations in ice volume

on front slope stability of berm breakwaters abstract the short communication presents application of the conventional van der meer stability formula for low crested breakwaters for the prediction of front slope erosion of statically stable berm breakwaters with relatively high berms the method is verified burcharth 2008 by comparison with the reshaping of a large norwegian breakwater exposed to the north sea waves as a motivation for applying the van der meer formula a discussion of design parameters related to berm breakwater stability formulae is given comparisons of front erosion predicted by the use of the van der meer formula with model test results including tests presented in sigurdarson and van der meer 2011 are discussed a proposal is presented for performance of new model tests with the purpose of developing more accurate formulae for the prediction of front slope erosion as a function of front slope relative berm height relative berm width method of armour stone placement and hydraulic parameters the formulae should cover the structure range from statically stable berm breakwaters to conventional double layer armoured breakwaters

the last interglacial glacial cycle mis 5 2 re examined based on long proxy records from central and northern europe abstract current multi proxy studies on a long sediment sequence preserved at sokli n finland i e in the central area of fennoscandian glaciations are drastically changing classic ideas of glaciations vegetation and climate in northern europe during the late pleistocene the sediments in the sokli basin have escaped major glacial erosion due to non typical bedrock conditions in this review the sokli record is compared in great detail with other long proxy records from central temperate and northern boreal europe these comprise the classic records of la grande pile e france and oerel n germany and more recently obtained records from horoszki duze e poland and lake yamozero nw russia the focus of the review is on pollen lithology and macrofossil and insect based temperature inferences the long records are further compared with recent proxy data from nearby terrestrial sites as well as with the rapidly accumulating high resolution proxy data from the ocean realm the comparison allows a re examination of the environmental history and climate evolution of the last interglacial glacial li g cycle mis 5 2 it shows that environmental and climate conditions during mis 5 ca 130 70 ka bp were distinctly different from those during mis 4 2 ca 70 15 ka bp mis 5 is characterized by three long forested intervals broadly corresponding to mis 5e 5c 5a both in temperate and northern boreal europe these mild periods were interrupted by two short relatively cold and dry intervals mis 5d and 5b with mountain centered glaciation in fennoscandia millennial scale climate events were superimposed upon these longer lasting climate fluctuations the time interval encompassing mis 4 2 shows open vegetation it is characterized by two glacial maxima mis 4 and 2 with sub continental scale glaciation over northern europe and dry conditions in strongly continental eastern european settings high amplitude climate oscillations of millennial duration characterized the climate variability of mis 3 mild climate conditions in early mis 3 caused large scale deglaciation of the fennoscandian ice sheet and ice free conditions with betula dominated vegetation including tree birch persisted over large parts of fennoscandia possibly interrupted by glaciation during major part of mis 3 till ca 35 ka bp overall mis 5 was mostly mild with warmest or peak interglacial conditions at the very start during mis 5e mis 4 2 was mostly cold with most extreme or peak glacial conditions in the closing phase during mis 2 this points to a subdivision of the last climate cycle into an early overall mild interglacial half and a late overall cold glacial half each with duration of ca 50 ka this review also shows that the climate variability in central and northern europe during the li g cycle was mostly in degrees of continentality with major shifts in winter temperature and precipitation values summer temperatures on the other hand remained largely unchanged it points to the waxing and waning of sea ice over the north atlantic ocean as a possible characteristic feature of the late pleistocene the present compilation based on long terrestrial sequences high resolution multi proxy data from the oceans and quantified paleo climate data strongly favors a definition of entire marine oxygen isotope stage 5 as the last interglacial similar as in the original marine stratigraphy and the stratigraphy at la grande pile in france the proxy based climate data places the start of the last glacial at the base of mis 4 and the northwest european pleniglacial it shows that the division between the eemian mis 5e and the early weichselian mis 5d a is not useful as not relevant from a climate point of view

the last interglacial glacial cycle in fennoscandia abstract the climate and glacier fluctuations during the last interglacial glacial cycle in fennoscandia seem to correspond roughly in time with the climate fluctuations recorded in france germany holland however the climate in fennoscandia was considerably colder and the coldest phases are recorded as periods with glacier fluctuations admittedly the exact age and amplitudes of some fluctuations are still much debated

the last glacial maximum on spitsbergen svalbard most scientists have concluded previously that the west coast of spitsbergen svalbard remained ice free during the late weichselian between 25 000 and 10 000 yr b p we conclude that the glaciation was more extensive terraces that were postulated to have been ice free are covered by a thin late weichselian till sudden drop in the marine limit and basal radiocarbon dates of raised glaciomarine sediments demonstrates that the glaciers in the main fjords isfjorden and van mijenfjorden terminated west outside of the fjord mouths basal radiocarbon dates from glaciomarine clay above till in cores from the continental shelf west of spitsbergen yielded ages of about 12 500 yr b p from which we conclude that the ice extended to the shelf edge based on the extent of amino acid diagenesis in radiocarbon dated molluscs the duration of the maximum extension of the late weichselian glaciation was short certainly less than 10 000 years during the ice free period preceding that glaciation at least back to 40 000 yr b p the glaciers on svalbard were not significantly larger than at present as shown by marine deposits close to the glacier snouts many radiocarbon dates place deglaciation of the outer coast at about 12 500 yr b p at about 10 000 yr b p the rest of the archipelago rapidly became ice free

mezen bay a key area for understanding weichselian glaciations in northern russia sediment successions in coastal cliffs around mezen bay southeastern white sea record an unusually detailed history of former glaciations interstadial marine and fluvial events from the weichselian a regional glaciation model for the weichselian is based on new data from the mezen bay area and previously published data from adjacent areas following the mikulinian eemian interglacial a shelf centred glaciation in the kara sea is reflected in proglacial conditions at 100 90 ka a local ice cap over the timan ridge existed between 75 and 65 ka renewed glaciation in the kara sea spread southwestwards around 60 ka only interrupted by a marine inundation before it advanced to its maximum position at about 55 50 ka after a prolonged ice free period the scandinavian ice sheet invaded the area from the west and terminated east of mezen bay about 17 ka the previously published evidence of a large ice dammed lake in the central arkhangelsk region lake komi finds no support in this study copyright c 2003 john wiley sons ltd

the esr age of portlandia arctica shells from glacial deposits of central latvia an answer to a controversy on the age and genesis of their enclosing sediments abstract the occurrence of portlandia arctica shells in glacigenic sediments of central latvia had created a controversy in many publications about 1 their age ranging from the holsteinian to the late weichselian and 2 the genesis of their enclosing sediments glacial glaciomarine or marine our reinvestigation of the main object of controversy the licupe site leads to a conclusion that the sedimentary package of diamictons clays and sands containing portlandia arctica shells and marine microfossils is a large glacial raft that had been transported and deposited by the riga lobe during the weichselian the electron spin resonance esr ages on five sets of portlandia arctica shells from the licupe and daugmales tom ni sites range from 86 0 6 8 to 105 0 9 2 ka bp these esr age determinations and the cool climate indicators of the associated microflora and microfauna suggest that their source sediments probably in the gulf of riga are marine clays of early weichselian age probably correlative to the brorup interstadial in central latvia portlandia arctica shells and their enclosing clay occur resedimented or translocated in glacial deposits during weichselian glacial advances

late pleistocene stratigraphy according to the sediment sequence from eastern kola peninsula ponoi river valley north western russia abstract the sedimentary sequence from the local stratotype section of the mikulinian mis 5 marine deposits at the ponoi river valley easternmost kola peninsula north western russia has been investigated to define the geological and numerical ages and chronostratigraphic position of a marine unit identified previously as a lithostratigraphic unit of the lower part of the mikulinian and named the ponoi beds in the regional kola stratigraphic scheme the new data indicate that the ponoi beds has two part sedimentary succession which was formed during two successive interglacial boreal and belomorian marine transgressions in the mikulinian mis 5 time the lower clay part of this succession accumulated in the interglacial marine basin until c 96 ka under favourable environmental and climatic conditions the upper sandy part of this lithostratigraphic formation also previously attributed to the ponoi beds accumulated in the late mikulinian marine basin about 70 ka ago under relatively cold and damp climate conditions in accordance with our new data obtained in this study it has to be attributed to another marine unit referred to as the strelna beds formed during the second belomorian interglacial marine transgression also during the mikulinian time formerly the strelna beds was correlated with the podporozhian mis 4 horizon in the current regional kola stratigraphic scheme both the ponoi and strelna beds marine sediments have to be related and linked with the marine basin during mis 5 these marine units have to be correlated with the mikulinian mis 5 horizon

shear wave velocity estimation in porous rocks theoretical formulation preliminary verification and applications shear wave velocity logs are useful for various seismic interpretation applications including bright spot analyses amplitude versus offset analyses and multicomponent seismic interpretations measured shear wave velocity logs are however often unavailable we developed a general method to predict shear wave velocity in porous rocks if reliable compressional wave velocity lithology porosity and water saturation data are available the precision and accuracy of shear wave velocity prediction are 9 and 3 respectively the success of our method depends on 1 robust relationships between compressional and shear wave velocities for water saturated pure porous lithologies 2 nearly linear mixing laws for solid rock constituents 3 first order applicability of the biot gassmann theory to real rocks we verified these concepts with laboratory measurements and full waveform sonic logs shear wave velocities estimated by our method can improve formation evaluation our method has been successfully tested with data from several locations

estimation of pressure saturation changes for unconsolidated reservoir rocks with high vp vs ratio abstractwe find that conventional time lapse seismic pressure saturation discrimination methods become unstable for high vp vs ratios using first order approximations in the amplitude variation with offset avo gradient and intercept changes and in the rock physics models increase the inaccuracy in pressure saturation changes estimates we propose a new method based on a stepwise linear approximation to the intercept and gradient reflectivity changes to estimate pressure and saturation changes the applicability of the new method is tested on synthetic data over a range of 0 50 gas saturation and 0 3 5 mpa pore pressure changes the new method is more consistent and provides better estimates compared with conventional methods in the presence of random noise up to 15 the estimates are reasonably better for the new method we use this new method to investigate the feasibility of pressure saturation discrimination for a shallow unconsolidated sand reservoir in which an underground blowout occurred

differences between the last two glacial maxima and implications for ice sheet δ18o and sea level reconstructions studies of past glacial cycles yield critical information about climate and sea level ice volume variability including the sensitivity of climate to radiative change and impacts of crustal rebound on sea level reconstructions for past interglacials here we identify significant differences between the last and penultimate glacial maxima lgm and pgm in terms of global volume and distribution of land ice despite similar temperatures and radiative forcing our analysis challenges conventional views of relationships between global ice volume sea level seawater oxygen isotope values and deep sea temperature and supports the potential presence of large floating arctic ice shelves during the pgm the existence of different glacial modes calls for focussed research on the complex processes behind ice age development we present a glacioisostatic assessment to demonstrate how a different pgm ice sheet configuration might affect sea level estimates for the last interglacial results suggest that this may alter existing last interglacial sea level estimates which often use an lgm like ice configuration by several metres likely upward

high resolution climate simulations of oxygen isotope stage 3 in europe abstract oxygen isotope stage 3 ois 3 climate and its variations are the focus of the stage 3 project the objective of the ois 3 modeling effort is twofold 1 to explore the importance of different boundary conditions on the climate of europe and 2 to develop climate simulations that best reproduce the wealth of ois 3 observations given the complexity of the topography and coastlines the modeling effort is based on a nested general circulation model gcm and mesoscale model regcm2 with climate simulations for europe on a 60 km grid spacing the key conclusions are as follows 1 the mesoscale model driven by gcm output does a reasonable job of reproducing the modern european climate 2 ois 3 variations in orbit co2 and ice sheet size are of little significance in explaining the observed climate variability 3 the model results focus attention on north atlantic sea surface temperatures sst as a major factor in explaining ois 3 climates 4 experiments for different sst values capture a number of systematic changes in sea level pressure and precipitation 5 climate models simulate substantial european cooling and significant changes in precipitation but they do not explain large differences between ois 3 warm and cold episodes

a new formula for the sea state and structural parameters influencing the stability of homogeneous reshaping berm breakwaters the berm recession of a reshaping berm breakwater has a very important role for the stability of this kind of structure based on a 2d experimental modeling method in a wave flume the recession of the berm due to sea state and structural parameters has been studied irregular waves with a jonswap spectrum were used a total of 215 tests have been performed to cover the impact of sea state conditions such as wave height wave period storm duration and water depth at the toe of the structure and structural parameters such as berm elevation from still water level berm width and stone diameter on berm recession in this paper first a new dimensionless parameter is introduced to evaluate the combined effect of wave height and wave period on berm recession using results of the experimental work then a formula that includes some sea state and structural parameters is derived using the new dimensionless parameter for estimating the berm recession a comparison is made between the estimated berm recessions by this new formula and formulae given by other researchers to show the preference of using the new dimensionless parameter the comparison shows that the recession estimated by the new formula has not only a better correlation with the present experimental data but also has an improved correlation with other experimental results within the range of parameters tested outside the range of parameters tested the lykke andersen 2006 formula performed best

on berm breakwaters recession crown wall wave forces reliability abstract the paper reviews different formulae lykke andersen 2006 lykke andersen and burcharth 2010 torum 2007 and moghim et al 2011 for recession of berm breakwaters and compares calculated recession with previous and new recession test data there are differences of the results by different formulae but by and large all the formulae give reasonable results on the recession for shallow water berm breakwaters it seems that the lykke andersen 2006 formula works best for the deep water cases although the torum 2007 formula seems to work as good for the homogenous berm breakwater case the moghim et al 2011 formula was not included in the comparison for the deep water cases because the deep water cases are outside the validity of the formula results of tests on different alternative berm breakwater designs which may be considered as practical economic designs have also been included but without any comparison with any formulae simply because the formulae do not cover the specific designs wave forces from model tests on crown walls on berm breakwaters are presented and compared with an existing formula for wave forces on a crown wall on conventional rubble mound breakwaters pedersen 1995 it appears that the wave forces on a crown wall on a berm breakwater are smaller than the wave forces on a crown wall on a conventional rubble mound breakwater finally a probability of failure analysis of a site specific berm breakwater the sirevag berm breakwater norway is presented using monte carlo simulations the probability of failure analysis shows that the sirevag berm breakwater is extremely strong

isotope stage 5 130 74 ka in greenland a review abstract marine and glacigene deposits dated with varying degrees of certainty to isotope stage 5 130 74 ka are exposed in coastal cliffs in 18 areas and localities in northern and eastern greenland dating methods include thermoluminescence tl u th methods and correlation with the deep sea record amino acid parameters are used for correlation between localities deposits from the last interglaciation isotope substage 5e are rare and have been found only at three localities in both west and east greenland their mollusc and foraminifer faunas indicate more vigorous sea surface circulation and sea surface temperatures some degrees higher than known from the holocene during this warm period ice sheet growth began in northwest greenland the ice sheet reached its maximum for the last ice age during the succeeding phase provisionally correlated with isotope substage 5d this was followed by a new warm period with increased influx of warm subarctic water and high summer temperatures on land provisionally correlated with isotope substage 5a in east greenland the observations indicate a more complex ice sheet history the record from greenland is very similar to that obtained in adjacent coastal areas of the high arctic implying that the rapid shifts from warm to cold during isotope stage 5 were especially conducive to the formation of the embryonic north american and scandinavian ice sheets at high northern latitudes probably because the pulses of warm water were required to advect sufficient moisture into these areas to allow the growth of continental ice sheets

late quaternary stratigraphy of western yamal peninsula russia new constraints on the configuration of the eurasian ice sheet ice sheet reconstructions for the last glacial maximum in northern eurasia range from nearly complete coverage by a contiguous marine based ice sheet to large unglaciated areas stratigraphic records from yamal peninsula russia provide new insight on the eastern limit of the eurasian ice sheet in the kara sea radiocarbon and infrared stimulated luminescence ages from coastal cliff sections date the emplacement of the kara diamicton as older than ca 40 ka reflecting regional glaciation ice wedge growth peat accumulation and eolian and fluvial deposition characterized the past 40 k y and do not support coverage of yamal peninsula by an ice sheet or proximity to a glacier margin thus the late weichselian eurasian ice sheet was largely confined to barents sea and its global sea level contribution is reduced to 7 m of sea level equivalent

theory of glacial erosion transport and deposition as a consequence of subglacial sediment deformation a theory of erosion transport and deposition of unlithified sediments by glaciers is presented it predicts the large scale areal distribution of zones and rates of erosion and deposition in time and space through a complete glacial cycle together with the resultant intensity of large scale lincations drumlins which will be incised in the landscape the theory also predicts the dispersal patterns of subglacial lithologies together with the form of dispersal trains derived from distinctive sources and the vertical and horizontal distribution of lithologies within a till it predicts major erosional discontinuities within tills and the formation of boulder pavements it suggests that the dominant proportion of the lowland tills produced by pleistocene mid latitude ice sheets was generated by subglacial deformation and explains why they are predominantly fine grained the theory is based on an analysis of glacier dynamic processes and therefore can be used to infer the dynamic behaviour of former ice sheets from the distribution of tills and their lithologic composition

the barents sea ice sheet a model of its growth and decay during the last ice maximum on the basis of geomorphological and sedimentological data we believe that the entire barents sea was covered by grounded ice during the last glacial maximum 14c dates on shells embedded in tills suggest marine conditions in the barents sea as late as 22 ka bp and models of the deglaciation history based on uplift data from the northern norwegian coast suggest that significant parts of the barents sea ice sheet calved off as early as 15 ka bp the growth of the ice sheet is related to glacioeustatic fall and the exposure of shallow banks in the central barents sea where ice caps may develop and expand to finally coalesce with the expanding ice masses from svalbard and fennoscandia the outlined model for growth and decay of the barents sea ice sheet suggests a system which developed and existed under periods of maximum climatic deterioration and where its growth and decay were strongly related to the fall and rise of sea level

on berm breakwaters stability scour overtopping abstract experimental studies on the stability of multilayer berm breakwaters have been carried out two stone mass densities have been used the results have been compared with the results of homogenous berm breakwaters and with other results of multilayer berm breakwaters an equation for the berm recession for homogenous berms has been derived including the effect of stone gradation and water depth erosion at and erosion protection of berm breakwaters have been investigated as well as wave overtopping discharges

estimation of rock physics properties from seismic attributes part 1 strategy and sensitivity analysis abstractthe quantitative estimation of rock physics properties is of great importance in any reservoir characterization we have studied the sensitivity of such poroelastic rock physics properties to various seismic viscoelastic attributes velocities quality factors and density because we considered a generalized dynamic poroelastic model our analysis was applicable to most kinds of rocks over a wide range of frequencies the viscoelastic attributes computed by poroelastic forward modeling were used as input to a semiglobal optimization inversion code to estimate poroelastic properties porosity solid frame moduli fluid phase properties and saturation the sensitivity studies that we used showed that it was best to consider an inversion system with enough input data to obtain accurate estimates however simultaneous inversion for the whole set of poroelastic parameters was problematic due to the large number of parameters and their trade off consequently we restricted the sensitivity tests to

morphology and stratigraphy from several deglaciations in the transtrand mountains western sweden the transtrand mountains western sweden are characterised by an abundance of glaciofluvial meltwater channels crossing lateral channels and channel systems overprinted by fluting occur at several localities drainage channel systems from three older deglaciations are interpreted to have been preserved despite overriding by later ice sheets deep sections machine excavated into the summit surface of the hundfjallet mountain revealed the presence of two lower diamictons into which two older generations of lateral channels were cut and subsequently buried by a late weichselian basal till buried frost sorted structures and frost fractured bedrock below the lowermost till indicate the repeated occurrence of periglacial condil conditions an organic layer between the two older units yielded an infinite radiocarbon age of 45000 yr bp the pollen content of this layer indicates a local mountain heath flora dominated by ericaceous dwarf shrubs and graminids the climate phase is interstadial or the beginning or end of an interglacial the different diamictons also display different pollen spectra during the last deglaciation the ice flow was from the north northeast the second youngest system of drainage channels corresponds to ice flow from approximately west northwest there are still older traces of separate deglaciation events from the east and north a frozen bed is interpreted to have been the standard basal regime for the last ice sheets to cover the transtrand mountains

deepwater geohazard prediction using prestack inversion of large offset p wave data and rock model successful deepwater drilling is defined as reaching the total well depth in the desired hole size safely i e not exceeding the fracture pressure while controlling hydrocarbon or water influx and ensuring that casings are placed across desired intervals the oil and gas industry has succeeded in this mission thousands of time around the world but drilling challenges abound especially in deepwater

relationships between compressional wave and shear wave velocities in clastic silicate rocks new velocity data in addition to literature data derived from sonic log seismic and laboratory measurements are analyzed for clastic silicate rocks these data demonstrate simple systematic relationships between compressional and shear wave velocities for water saturated clastic silicate rocks shear wave veloci ty is approximately linearly related to compressional wave velocity and the compressional to shear velocity ratio decreases with increasing compressional velocity laboratory data for dry sandstones indicate a nearly constant compressional to shear velocity ratio with rigidity approximately equal to bulk modulus ideal models for regular packings of spheres and cracked solids exhibit behavior similar to the observed water saturated and dry trends for dry rigidity equal to dry bulk modulus gassmann s equations predict velocities in close agreement with data from the water saturated

fennoscandian palaeoglaciology reconstructed using a glacial geological inversion model the evolution of ice sheet configuration and flow pattern in fennoscandia through the last glacial cycle was reconstructed using a glacial geological inversion model i e a theoretical model that formalises the procedure of using the landform record to reconstruct ice sheets the model uses mapped flow traces and deglacial melt water landforms as well as relative chronologies derived from cross cutting striae and till lineations as input data flow trace systems were classified into four types i time transgressive wet bed deglacial fans ii time transgressive frozen bed deglacial fans iii surge fans and iv synchronous non deglacial event fans using relative chronologies and aggregation of fans into glaciologically plausible patterns a series of ice sheet configurations at different time slices was erected a chronology was constructed through correlation with dated stratigraphical records and proxy data reflecting global ice volume geological evidence exists for several discrete ice sheet configurations centred over the scandinavian mountain range during the early weichselian the build up of the main weichselian fennoscandian ice sheet started at approximately 70 ka and our results indicate that it was characterised by an ice sheet with a centre of mass located over southern norway this configuration had a flow pattern which is poorly reproduced by current numerical models of the fennoscandian ice sheet at the last glacial maximum the main ice divide was located overthe gulf of bothnia a major bend in the ice divide was caused by outflow of ice to the northwest over the lowest part of the scandinavian mountain chain widespread areas of preserved pre late weichselian landscapes indicate that the ice sheet had a frozen bed core area which was only partly diminished in size by inward transgressive wet bed zones during the decay phase

late pleistocene in the southeastern white sea and adjacent areas arkhangelsk region russia stratigraphy and palaeoenvironments abstract an overview of the late pleistocene and holocene stratigraphy of the southeastern white sea region is presented in the paper based upon the analysis of published data new results and correlation between marine and terrestrial archives the pleistocene stratigraphic record in the southeastern white sea region begins with mikulino horizon which comprises the whole mis 5 and is composed of marine sediments sands sandy clays and clays with boreal arctic boreal and lusitanean boreal microfauna and mollusc fauna dated back at 161 77 ka the podporozhie horizon in the southeastern white sea region comprises the mis 4 71 57 ka complex of marine mostly near shore sediments the glaciation during mis 4 was localized on one hand within the kola peninsula on the other hand the glacier probably overlapped the kanin peninsula and the mezen bay however the gorlo strait was not blocked and the northward river outflow was preserved the leningrad horizon had been formed also in the marine sedimentation pattern during the mis 3 57 29 ka however the lack of data in the region allows us to make only the comparative analysis the ostashkov horizon mis 2 29 11 7 ka is composed of the deposits of glacial paragenetic series tills glaciofluvial glaciomarine and glaciolacustrine deposits but also comprises the deglaciation late glacial sedimentary complex including marginal tills the holocene stratigraphic record is subdivided into three stages 11 7 9 5 9 5 3 5 and 3 5 0 ka bp and do not match with new formal stratigraphic subdivision of the holocene series

pleistocene marine deposits in the coastal areas of kola peninsula russia abstract on the basis of field data datings from both electron spin resonance and optically stimulated luminescence and micro and macrofauna in addition to presence of diatoms three late pleistocene marine units have been identified in the coastal areas of the kola peninsula the stratigraphically lowest sequence is correlated to the ponoi beds and the boreal transgression attributed to the marine isotope stages mis 5e to 5d in the white sea depression and to mis 5e to 5c in the barents sea thermophilic fauna and diatoms indicate normal water salinity and a water temperature above zero the second marine unit referred as the strel na beds can be correlated with the early weischselian transgression termed the belomorian transgression with low water salinity and a water temperature similar or colder than the present times belomorian transgressions are reliably detected in the white sea and are not clearly found in the barents sea the results obtained from the sediments of the ponoi and strel na beds indicate a continuously existing marine reservoir from 130 to 80 70 ka ago entire mis 5 in the white sea depression the early middle weichselian barents kara ice sheet invasion and its recession might have caused the glacioeustatic middle weichselian mis 3 transgression and the third late pleistocene marine sequence has been deposited in the regressing shallow cold sea with less saline waters the results help in the understanding of the history of late quaternary ice sheets in north eurasia and provide evidence for the debatable early and middle weichselian marine events

cenozoic microfossils in northern finland local reworking or distant wind transport abstract allochthonous cenozoic microfossils have been reported from late pleistocene lake and mire host sediments across an area of 30 000 km2 in northern finland two main groups of microfossils are recognised palaeogene marine diatoms silicoflagellates and ebridians that include taxa from around the time of the palaeocene eocene thermal maximum and pliocene to early pleistocene freshwater diatoms the presence of these microfossils has been regarded as evidence that eocene marine and late neogene freshwater sediments formerly existed on the shield surface both groups have been referred to frequently in reconstructions of the sea level tectonic and erosion history of the northern fennoscandian shield the questions raised by the presence of allochthonous cenozoic microfossils in northern finland are however strongly resonant of the debate over the biota origin and age of the pliocene sirius group in antarctica where competing hypotheses have been put forward of local deposition and reworking versus distant wind transport of marine diatoms from the continental shelf this review explores alternative origins for the allochthonous cenozoic microfossils in northern finland local reworking of palaeogene marine sediments during pleistocene glaciation is unlikely as no source rocks of palaeogene age are known from the shield surface or from surrounding sedimentary basins in the baltic and white sea moreover at all sites except akanvaara the marine diatom taxa cover wide age ranges and occur only as minor components in diatom assemblages that are dominated by quaternary freshwater taxa local reworking of pliocene pleistocene freshwater diatoms is however compatible with the widespread survival of pre pleistocene deep weathering although no in situ or unmixed ice rafted pliocene pleistocene lacustrine sediment has yet been found an alternative origin for the marine palaeogene microfossils by distant wind transport is proposed in this hypothesis palaeogene diatomites on the barents sea shelf were exposed to deep glacial and fluvioglacial erosion during the pliocene and early pleistocene and in low sea level stages of the middle and late pleistocene intense wind action acting on comminuted mudstones on outwash plains carried dust including microfossils into northern fennoscandia to be deposited by rain out in lakes and wetlands this material may have been later further recycled by glacial and meltwater transport and more localised wind action processes that also may help to account for the distribution of eemian marine diatoms well beyond eemian shorelines the distant wind transport hypothesis implies that the presence of marine palaeogene diatoms on the shield surface in northern finland cannot be regarded as vestiges of former marine sediments and so do not constrain the tectonic and geomorphic history of the northern fennoscandian shield in the cenozoic

new radiocarbon dates from finnish mammoths indicating large ice free areas in fennoscandia during the middle weichselian new radiocarbon dates from finnish subfossil mammoth material mammuthus sp transported by glacial ice range in age from ca 32000 to ca 22500 yr bp these results suggest that there was a larger ice free area in fennoscandia during the middle weichselian than previously assumed in addition two dates are also presented for bones found in clay with a different transport history copyright 1999 john wiley sons ltd

the early and middle weichselian interstadials in the central area of the scandinavian glaciations abstract in the central parts of the scandinavian glaciations in norway sweden and finland there are a number of early weichselian sites with fresh water sediments which by comparison with sites further south can be correlated with either the brorup or odderade interstadials few of these sites can with any certainty be correlated with just one of the two in northern jutland and at thecoast of south western norway there are early weichselian marine sediments some of those in norway having been interpreted as interstadial middle weichselian fresh water sediments have only been found in denmark and southern sweden whereas marine sediments occur in northern jutland and at the coast in norway in the same areas as the early weichselian marine sediments most of the middle weichselian sites must be referred to as representing an interstadial complex as a close correlation with the five interstadials identified in northwest germany and the netherlands is not possible a close correlation has been made between the fluctuations in the deep sea oxygen isotope curve and the weichselian history in scandinavia the justification for which is discussed

age dating and the orbital theory of the ice ages development of a high resolution 0 to 300 000 year chronostratigraphy using the concept of orbital tuning a continuous high resolution deep sea chronostratigraphy has been developed spanning the last 300 000 yr the chronology is developed using a stacked oxygen isotope stratigraphy and four different orbital tuning approaches each of which is based upon a different assumption concerning the response of the orbital signal recorded in the data each approach yields a separate chronology the error measured by the standard deviation about the average of these four results which represents the best chronology has an average magnitude of only 2500 yr this small value indicates that the chronology produced is insensitive to the specific orbital tuning technique used excellent convergence between chronologies developed using each of five different paleoclimatological indicators from a single core is also obtained the resultant chronology is also insensitive to the specific indicator used the error associated with each tuning approach is estimated independently and propagated through to the average result the resulting error estimate is independent of that associated with the degree of convergence and has an average magnitude of 3500 yr in excellent agreement with the 2500 yr estimate transfer of the final chronology to the stacked record leads to an estimated error of 1500 yr thus the final chronology has an average error of 5000 yr