holocene climatic and environmental changes inferred from midge records diptera chironomidae chaoboridae ceratopogonidae at lake berkut southern kola peninsula russia a radiocarbon dated sediment sequence from lake berkut in the southern part of the kola peninsula northwest russia was investigated by means of midge analysis in order to reconstruct the holocene climatic and environmental history of the region past mean july air temperatures at the study site and hypolimnetic oxygen contents of the lake water were inferred from chironomid based transfer functions the early holocene c 10 100 8400 cal yr bp is characterized by summer temperatures and hypolimnetic oxygen concentrations broadly similar to present day conditions the midge records give evidence of a lake level fall at c 7000 cal yr bp resulting in weakened thermal stratification of the lake water and improvement of the hypolimnetic oxygen conditions after c 4000 cal yr bp midge assemblages suggest a lake level rise related to increased effective moisture a secondary mid holocene climatic optimum with inferred mean july air temperatures of c 12 1 degrees c was recorded between 6000 and 4400 cal yr bp followed by minimum values c 11 3 degrees c between 3500 and 1500 cal yr bp accompanied by the onset of natural acidification of the lake the late holocene midge assemblages suggest weakly acidic conditions low hypolimnetic oxygen contents and a general warming trend during the last c 1500 years although paludification and natural acidification may have influenced the temperature reconstruction at this stage however the modern chironomid inferred mean july air temperature 12 5 degrees c is consistent with meteorological data from a nearby station in general the midge records reflect relatively warm and moist conditions at lake berkut before c 7000 cal yr bp a relatively warm and dry climate at c 7000 4000 cal yr bp and a shift to cooler and wetter climatic conditions in the region after c 4000 cal yr bp less

holocene climate variability on the kola peninsula russian subarctic based on aquatic invertebrate records from lake sediments sedimentary records of invertebrate assemblages were obtained from a small lake in the khibiny mountains kola peninsula together with a quantitative chironomid based reconstruction of mean july air temperature these data provide evidence of holocene climate variability in the western sector of the russian subarctic the results suggest that the amplitude of climate change was more pronounced in the interior mountain area than near the white sea coast a chironomid based temperature reconstruction reflects a warming trend in the early holocene interrupted by a transient cooling at ca 8500 8000 cal yr bp with a maximum drop in temperature ca 1 c around 8200 cal yr bp the regional holocene thermal maximum characterized by maximum warmth and dryness occurred at ca 7900 5400 cal yr bp during this period july temperatures were at least 1 c higher than at present the relatively warm and dry climate persisted until ca 4000 cal yr bp when a pronounced neoglacial cooling was initiated minimum temperatures ca 1 2 c lower than at present were inferred at ca 3200 3000 cal yr bp faunal shifts in the stratigraphic profile imply also that the late holocene cooling was followed by a general increase in effective moisture

observations on the nature and origin of fusain abstract evidence for a wildfire origin of fusain is examined charcoal produced by natural fires and artificial charring resembles fossil fusain both in physical size and shape and in optical reflectance artificially charred leaves and naturally burnt wood are illustrated using the sem reflectance studies on modern charcoals suggest that much semifusinite may be produced by pyrolysis the ecological implications of a wildfire origin of fusain are discussed and it is concluded that fires have been a feature of terrestrial ecosystems from at least the late devonian

holocene tree line dynamics and inferred climatic changes in the abisko area northern sweden based on macrofossil and pollen records lake sediment records of pollen and macroscopic plant remains of terrestrial origin provide evidence of long term changes in forest composition close to the altitudinal tree line in the abisko area northernmost sweden a dominance of mountain birch betula pubescens ehrh ssp tortuosa ledeb nyman with a field layer of ferns grasses and sedges suggests that an oceanic climate with relatively high precipitation existed during the early holocene macrofossils of mountain birch were found 300 400 m above the present tree line which corresponds to a 1 5 2 c higher summer temperature than at present scots pine pinus sylvestris was present to some extent at altitudes above its present limit during the early holocene a pronounced expansion of pine took place above its present limit around 6300 cal bp 5500 bp this is interpreted as a result of successively drier and more continental climatic conditions a decreased abundance of pine from c 5200 cal bp 4700 bp followed by a gradual retraction of

mid holocene warming in the northwest kola peninsula russia northern pine limit movement and stable isotope evidence a set of 40 subfossil scots pines pinus sylvestris l was sampled in small lakes beyond the modernpine limit in the northwest kola peninsula russia radiocarbon dating suggests that the pine exp

hydroclimatic changes over the past 900 years documented by the sediments of tiewaike lake altai mountains northwestern china abstract the reconstruction of variations in effective moisture over the past millennium are important for assessing potential future climatic trends in environmentally sensitive arid central asia aca especially in the context of ongoing global warming however high resolution time series reflecting past moisture variability in the region are scarce thus preventing a full understanding of the hydroclimatic evolution here we present the results of multi proxy analysis of a sediment core spanning the past 900 years from tiewaike lake in the altai mountains northern xinjiang the climatic proxies measured include grain size organic matter and carbonate content c n ratio and the stable carbon isotope composition of bulk organic matter the results show that over the past 900 years the climatic evolution of the study area can be divided into distinct hydroclimatic phases the arid medieval climate anomaly mca 1090 1430 ad the humid little ice age lia 1430 1940 ad and the arid current warm period cwp 1940 2012 ad during the lia the water level at tiewaike lake was overall higher than during the other climatic intervals in addition the lia climate was unstable and characterized by six intervals with the occurrence of heavy precipitation events on a multi decadal timescale a humid unstable climate during the lia is also suggested by climatic records from adjacent regions our results support the view that over the past millennium on a multi centennial timescale the moisture variations in aca were generally out of phase with those in the region affected by the asian summer monsoon the humid unstable lia climate in aca may have been associated with changes in the north atlantic oscillation nao index and or with variations in solar irradiance

mediaeval climatic warming recorded by radiocarbon dated alpine tree line shift on the kola peninsula russia studies of the tree line history in northern fennoscandia provide useful evidence about the holocene environment and the region s climatic history here we report on late holocene alpine tree line movement in the khibiny low mountains on the kola peninsula northwestern russia a highly representative collection of subfossil woods above the modern tree line was obtained and 49 pine samples were radiocarbon dated their radiocarbon ages range from c 1400 to 3000 yr bp with a distinct maximum between c 800 and 1000 yr bp about cal ad 1000 to 1300 we conclude that especially during the mediaeval climatic optimum pine forests grew at least 100 140 m above the modern pine tree line in the khibiny mountains

petrology depositional environment and utilization potential of late paleocene coals from the obed marsh deposit west central alberta canada abstract the obed marsh coal deposit is of late paleocene age and contains over 200 million tons of subbituminous b to high volatile bituminous c coal petrographic analysis of three sections from seams 1 and 2 reveals high amounts of huminite and relatively low amounts of liptinite and inertinite with the exception of some intervals in both seems the persistent high ratio of huminite to liptinite and inertinite indicates a relatively reducing environment a feature also expressed by the relatively low inertinite content examination of the in seam profiles also indicates undisturbed peat accumulation over long periods of time the obed coals similar in rank and composition to the hat creek coals of british columbia formed in a freshwater environment and can be used as feedstock for combustion gasification furthermore the intervals rich in liptinite and petroleum like substances may be utilized for liquefaction hydrogenation

the holocene vegetation history of the khibiny mountains implications for the post glacial expansion of spruce and alder on the kola peninsula northwestern russia

holocene humidity changes in northern finnish lapland inferred from lake sediments and submerged scots pines dated by tree rings conclusive evidence for a rise in water levels has been found in connection with lake sediment studies undertaken partly in collaboration with the pine megafossil sampling and dendrochronological work in northern finnish lapland the change in lake level stands is shown by slow sedimentation rate in the early to mid holocene and an increase thereafter these data indicate a regional rise in water levels during the latter part of the holocene following a relatively dry period between 8000 and 4000 bp synchronous changes also indicating rising water levels have been observed in the diatom and cladoceran assemblages of the sediment cores subfossil scots pines pinus sylvestris l have been preserved in large quantities in small lakes in lapland because in many cases the rising water level has inundated the trunks after death the position of the subfossil trunks and stumps often indicates that the pines have been growing on dry land at the sides of the lakes in which they are now submerged traces of

coupled conduit and atmospheric dispersal dynamics of the ad 79 plinian eruption of vesuvius abstract the ad 79 eruption of vesuvius is certainly one of the most investigated explosive eruptions in the world this makes it particularly suitable for the application of numerical models since we can be quite confident about input data and the model predictions can be compared with field based reconstruction of the eruption dynamics magma ascent along the volcanic conduit and the dispersal of pyroclasts in the atmosphere were simulated the conduit and atmospheric domain were coupled through the flow conditions computed at the conduit exit we simulated two different peak phases of the eruption which correspond to the emplacement of the white and gray magma types that produced plinian fallout deposits with interlayered pyroclastic flow units during the gray phase the input data independently constrained and representative of each of the two eruptive phases consist of liquid magma composition crystal and water content mass flow rate and pressure temperature depth of the magma at the conduit entrance a parametric study was performed on the less constrained variables such as microlite content of magma pressure at the conduit entrance and particle size representative of the eruptive mixture numerical results are substantially consistent with the reconstructed eruptive dynamics in particular the white eruption phase is found to lead to a fully buoyant eruption plume in all cases investigated whereas the gray phase shows a more transitional character i e the simultaneous production of a buoyant convective plume and pyroclastic surges with a significant influence of the microlite content of magma in determining the partition of pyroclast mass between convective plumes and pyroclastic flows

palynostratigraphic zonation of paleocene strata in the central and south central alberta plains paleocene strata of the scollard and paskapoo formations in the central and south central alberta plains can be subdivided into five formal biostratigraphic zones based in part on a momipites cary

late glacial and holocene paleoceanography and sedimentary environments in the st anna trough eurasian arctic ocean margin based on stratigraphical analysis of twelve sediment cores from the saint anna trough we reconstruct changes in paleoceanography and sedimentary environment during the last deglaciation and the holocene detailed analysis of benthic and planktic foraminiferal fauna stable oxygen and carbon isotope analysis lithostratigraphy and radiocarbon dates are used to reconstruct the following evolution after the deglaciation of the saint anna trough 13 300 yr b p until 9500 yr b p the environment was mainly characterised by low biogenic production carbonate dissolution and deposition of proximal to distal glaciomarine sediments intervals with high abundance of the benthic foraminifer cassidulina teretis may indicate influx of atlantic water at bottom the transition into the present interglacial started at 9500 yr b p reflected by increased production of foraminifera and bivalves after 8000 yr b p there was a marked drop in planktic 18o followed by a rise in planktic foraminifera and subsequently an increase of c teretis these paleoceanographic changes reflect increased heat transport into the area and are coupled to changes in nordic seas the early holocene warming of the saint anna trough were delayed by ca 2000 years relative to the northeast nordic seas early holocene sedimentation rates were relatively high 100 cm 1000 yr declining drastically after 8000 yr b p 50 cm 1000 yr this was presumably caused by reduction in winnowing and or riverine input

palynofacies coal petrographic facies and depositional environments amphitheatre formation eocene to oligocene and ravenscrag formation maastrichtian to paleocene canada abstract low rank coals from two disparate geological settings have been subjected to petrographic and palynological analysis the stratigraphic units studied and their locations are the amphitheatre formation st elias mountains yukon territory of eocene to oligocene age and the base of the ravenscrag formation south central saskatchewan of latest cretaceous to earliest paleocene age the depositional setting of the amphitheatre formation ranges from distal sand dominated braided stream and lacustrine environments to proximal gravel dominated fluvial environments the coals are low in inertinite 85 in localities with a dominance of angiosperm pollen the relative abundance of eu ulminite b and densinite is greatest whereas in the ones with a dominantly coniferous pollen assemblage eu ulminite a is the most prominent maceral these observations suggest as an immediate cause effect relationship an at least partial dependance of present maceral content on floral precursors this in turn probably reflects a certain combination of depositional environment conditions ph eh temperature etc that likely controlled the plant community and the preservation of vegetal matter the depositional environment of coals from the basal part of the ravenscrag formation contrasts sharply with that of the amphitheatre the ravenscrag coals formed within a low energy stable floodplain environment palynological and coal maceral profiles for the basal ravenscrag formation coal which spans the cretaceous tertiary boundary indicates that the environment of deposition progressed from an open canopied swamp forest with areas of open water through a phase of low lying to open water swamps with herbaceous pterophytic vegetation to at least locally raised bogs the change in coal petrography across the cretaceous tertiary boundary is shown to be relatively minor in comparison to subsequent changes in coal petrography in the earliest paleocene and to changes that occur in the palynological assemblages across the boundary interval

radiocarbon dated pinus sylvestris l wood from beyond tree line on the kola peninsula russia radiocarbon dates were obtained from 24 samples of pinus sylvestris l scots pine wood recovered from sites beyond the modern conifer tree line on the kola peninsula of russia twenty one of the samples came from the shallow waters and eroding peats at the edges of two small lakes at 68 439n 35 109e located north of the modern conifer tree line three samples came from a small pond located above the modern elev ational limits of pinus sylvestris at 68 259n 35 199e the radiocarbon dates indicate that pine trees grew approximately 20 km north of the mapped modern limits of the species from 6680 bp to 3830 bp pine trees were also growing some 40 m above their modern elevational limits between 5890 bp and 3450 bp nineteen of the samples date from 6680 bp to 5070 bp suggesting that the density of trees north of the modern tree line was greatest between 7000 and 5000 bp the timing of tree line advance and greatest density on the kola peninsula are in agreement with the results of similar studies from northern fennoscandia which indicate that maximum northern and elevational extension of tree line occurred between 7000 bp and 4000 bp the general agreement between tree line reconstructions suggests that the climatic changes that promoted mid holocene tree line extension along the north atlantic margins in northern fennoscandia propagated eastward to the kola peninsula the late timing of initial pine expansion on the kola and in adjacent northern fennoscan dia remains problematic and may relate to lower winter insolation temperature regimes in the adjacent oceans or slow rates of migration

holocene vegetation history and climate change on the northern kola peninsula russia a case study from a small tundra lake abstract a sediment core from lake kp3 unofficial name located near the coastline on the northern kola peninsula 100 km east south east from murmansk russia 69 04 19 n 36 00 40 e provides palynological evidence for the vegetation and climate history of the last 14 000 years during the younger dryas time the climate was cold and vegetation cover around the lake consisted of a shrub birch willow tundra with warming during the early holocene birch forest expanded across the kola peninsula and by 9500 cal yr bp a dense birch tree forests likely extended as far north as the modern barents sea coastline by about 7800 cal yr bp alnus incana was present as an admixture to birch in wet places as far north as the barents sea shoreline scots pine expanded to north of its modern limits on the kola peninsula between 7900 and 3700 cal yr bp with its maximum northward progress and abundance at 7300 6200 cal yr bp although scattered pines may have grown near the coastline pine forests did not reach the barents sea coastal area and the region remained covered with birth forest tundra as much as during earlier holocene the expansion of birch forest and pine forest in the early to mid holocene likely reflects the impact of higher amounts of summer radiation due to milankovitch forcing and warmer temperatures in the north atlantic ocean and barents sea the mid holocene summer warming in the barents sea coastal area likely ranged from 1 c to 1 5 c above modern conditions following 5900 cal yr bp shrub tundra communities began to replace birch forest and pines on the northernmost kola peninsula the modern tundra which occupies the coastal region near lake kp3 was established at about 3100 cal yr bp the vegetation and climatic changes evident on the northern kola peninsula are similar to those evident in northernmost fennoscandia

petrographyof some fraser river delta peat deposits coal maceral and microlithotype precursors in temperate climate peats abstract peat deposits on the recent lobe of the fraser river delta british columbia have accumulated in a variety of depositional settings the study of the decomposition of the plant components associated with each depositional area has enabled prediction of the occurrence and distribution of the precursors of the loal macerals and microlithotypes on inactive portions of the distal lower delta plain thin sedge grass peats ave developed these peats were influenced by marine conditions near the base and freshwater conditions higher in the section a high ratio of cellulose to lignin in marsh plants and limited exposure of these tissues to desiccation and oxidation prodcue primarily desmocollinite smaller amounts of cernite cutinite and alganite origginate from algal and sedge lipids in the transition to freshwater peats oxyfusinite pyrofusinite and micrinite partially replace former exinite and vitrinite group maceral precursors subsequent transgression by marine waters has further promoted decomposition of the peat laterally extensive but thin and discontinouus coal seams which would develop from such peat will contain vitrite bands near the base and grade upsection into interlamlaminated durite and vitrinertite peats deposited between the upper and lowerdelta plain originate from brackish water as such earliest peat horizons contain similar maceral compositions to thoce encountered in distal delta plain deposits crevasse and fire splays disrupt gradational changes in fabric upsection and along channel margins flooding by oxygenated neutral ph waters followed by extended periods of desicaation result in increases of inertodetrinite macrinite sclerotinite and oxyfusinite interlaminated durites and vitrinertites will form common microlithotypes interbedded bands of telinite cutinite and cerinite are produced by later freshwater sedge grass peat accumulations in this biofacies clarite replaces durite after colonization by sphagnum lignin rich tissues from ericaceous shrubs and pinus contorta provide precurssors for subernnite telocollinite and telinite stumps of massive telinite interrupt these banded macerals coal seams originating from such peats would be thick laterally extensive and characterized by vitrite with laminae of liptite and lenses of clarite in the upper part

maceral distributions in illinois coals and their paleoenvironmental implications abstract for purposes of assessing the maceral distribution of illinois u s a coals analyses were assembled for 326 face channel and drill core samples from 24 coal members of the pennsylvanian system the inertinite content of coals from the missourian and virgilian series averages 16 1 mineral free compared to 9 4 for older coals from the desmoinesian and older series this indicates there was generally a higher state of oxidation in the peat that formed the younger coals this state probably resulted from greater exposure of these peats to weathering as the climate became drier and the water table lower than was the case for the older coals although oxidation during allochthonous deposition of inertinite components is a genetic factor that needs further study to confirm the importance of the climate regional variation of the vitrinite inertinite ratio v i on a mineral and micrinite free basis was observed in the springfield no 5 and herrin no 6 coal members to be related to the geographical position of paleochannel river deposits known to have been contemporaneous with the peats that formed these two coal strata the v i ratio is highest generally 12 27 in samples from areas adjacent to the channels and lower 5 11 some 10 20 km away we interpret the v i ratio to be an inverse index of the degree of oxidation to which the original peat was exposed high v i ratio coal located near the channels probably formed under more anoxic conditions than did the lower v i ratio coal some distance away from the channels the low v i ratio coal probably formed in areas of the peat swamp where the watertable was generally lower than the channel areas

petrology of fibrous coal fusain and associated inertinites from the early paleocene of the central alberta plains abstract megascopic micropetrographic and scanning electron microscopic investigations of fibrous coal indicate that paleo wildfires were common occurrences in the mire which produced highvale coals at least 20 fibrous coal fusain horizons have been identified in corehole samples from the pit no 3 locality at highvale in the central alberta plains thicknesses of individual horizons vary and are not particular to any stratigraphic position within coal seams the majority of these fibrous horizons is within the two thick economic seams the highvale nos 1 and 2 which are characteristically megascopically dull the dullness of given lithotypes is largely related to inertinite content with fibrous coal containing 51 inertinite on average and selected horizons comprised of as much as 85 inertinite semifusinite and inertodetrinite are the predominant inertinites with a few horizons exhibiting highly reflecting fusinite macrinite is rare and micrinite is absent sem investigations reveal that certain fibrous coals exhibit excellent preservation of the original gymnospermous taxodium woody tissue features such as homogenization and swelling of the cell walls elimination of the middle lamellae and preservation of bordered pits are clearly indicative of charcoal formation as a product of paleo wildfires depending upon the nature of the fire temperatures obtained and the nature of the mire vegetation a wide range of inertinite precursors can be produced

holocene treeline history and climate change across northern eurasia radiocarbon dated macrofossils are used to document holocene treeline history across northern russia including siberia boreal forest development in this region commenced by 10 000 yr b p over most of russia forest advanced to or near the current arctic coastline between 9000 and 7000 yr b p and retreated to its present position by between 4000 and 3000 yr b p forest establishment and retreat was roughly synchronous across most of northern russia treeline advance on the kola peninsula however appears to have occurred later than in other regions during the period of maximum forest extension the mean july temperatures along the northern coastline of russia may have been 2 5 to 7 0 c warmer than modern the development of forest and expansion of treeline likely reflects a number of complimentary environmental conditions including heightened summer insolation the demise of eurasian ice sheets reduced sea ice cover greater continentality with eustatically lower sea level and extreme arctic penetration of warm north atlantic waters the late holocene retreat of eurasian treeline coincides with declining summer insolation cooling arctic waters and neoglaciation

paleoceanographic reconstructions of surface ocean conditions in the greenland iceland and norwegian seas through the last 14 ka based on diatoms prior reconstructions of the last glacial maximum and the holocene did not include detailed paleoclimate data from the greenland iceland and norwegian gin seas which cover sensitive areas for oceanographic boundaries sea ice distribution and deep water formation in order to fill this gap we studied nine well dated sediment cores from this area and reconstructed the paleoceanographic conditions of the surface gin seas at 2000 year intervals since 13 400 bp based on the diatom record results show that a n s extending sea ice free corridor had opened along norway already at 13 400 bp indicating a northward flow of a branch of the north atlantic drift possibly caused by a change in the jet stream flow due to the decreased height of the north american ice sheet a major change of climatic conditions occurred over the gin seas as the insolation anomaly reached its maximum around 9000 bp when the sea ice cover and the oceanic fronts retreated to a northwesterly position along greenland and the ocean temperatures rose the first half of the holocene is recorded as the warmest period during the last 13 400 bp in the gin seas the duration of this climatic optimum decreased both toward the north and toward the margins of the area the second half of the holocene is characterized by a cooling trend in step with the decreasing insolation these results support the proposal of imbrie et al 1992 that the gin seas region acts as an initial responder to insolation changes