late quaternary tephrochronology of sweden a review abstract studies of late quaternary sediments in south and central sweden have yielded a detailed tephrochronology for the last glacial interglacial transition lgit ca 15 000 10 000 cal yr bp and the holocene more than ten tephra layers have been detected and geochemically characterised the most widespread tephra from the lgit is the rhyolitic phase of the vedde ash ca 12 000 cal yr bp which has been found in lacustrine sediments and marine clays south of the younger dryas moraines in south sweden other horizons from the lgit identified to date include the borrobol tephra ca 14 400 cal yr bp the hasseldalen tephra ca 11 500 cal yr bp the 10 ka askja tephra ca 11 300 cal yr bp and the hogstorpsmossen tephra ca 10 200 cal yr bp the most significant holocene isochrones are hekla 4 ca 4260 cal yr bp hekla selsund kebister ca 3750 cal yr bp hekla 3 ca 3000 cal yr bp and askja 1875 two new late holocene tephra horizons the stomyren tephra ca 2100 cal yr bp and the gullbergby tephra ca 2700 cal yr bp were identified in single sites and are so far less valuable as marker horizons but are potentially important for the future

impact of the late glacial eruption of the laacher see volcano central rhineland germany abstract within a period of a few weeks toward the end of the allerod interstadial the major plinian eruption of the laacher see volcano produced some 20 km3 of eruptiva covering and preserving the late glacial landscape in the german central rhineland over an area of more than 1000 km2 correlation of terrestrial archives with the greenland ice core records and improved calibration of the radiocarbon timescale permit a precise accurate age determination of the laacher see event some 200 yr before the onset of the younger dryas cold episode carbonized trees and botanical macrofossils preserved by laacher see tephra permit detailed regional paleoenvironmental reconstruction and show that open woodland were typical for the cool and humid hemiboreal climatic conditions during the late allerod this woodland provided the habitat for a large variety of animal species documented at both paleontological and final paleolithic archeological sites preserved below laacher see deposits of special interest are numerous animal tracks intercalated in middle laacher see deposits at the south of the neuwied basin this knowledge may help to evaluate possible supraregional impacts of this volcanic event on northern hemispheric environment and climate during the late allerod

constraining the time span between the early holocene hasseldalen and askja s tephras through varve counting in the lake czechowskie sediment record poland we report the first findings of coexisting early holocene hasseldalen and askja s cryptotephras in a varved sediment record in lake czechowskie poland a time span of 152 11 8 varve years between the two tephras has been revealed by differential dating through varve counting this is in agreement within the uncertainties with calculations from radiocarbon based age models from the non varved hasseldala port record in southern sweden but shorter than assumed from the non varved lake record on the faroe islands we discuss possible reasons for the observed differences in duration between the two tephras and provide a revised absolute age for the askja s tephra of 11 228 226 cal a bp based on anchoring our floating varve chronology to the absolute timescale by using the hasseldalen tephra as dated in the hasseldala port sediments 11 380 216 cal a bp this age agrees with radiocarbon age models with larger uncertainty ranges but is slightly older than radiocarbon based age models with narrow uncertainty bands and is even 200 300 years older than the age reported from the faroe islands record in addition to these chronological issues we discuss the possible response of the czechowskie sediment record to the preboreal climate oscillation

tephrochronology and absolute centennial scale synchronisation of european and greenland records for the last glacial to interglacial transition a case study of soppensee and ngrip the tephrostratigraphy of soppensee switzerland is presented here for the first time with new geochemical data for four tephra layers derived from three volcanic centres the best available age estimates for the laacher see tephra and vedde ash layers are incorporated into a revision of the radiocarbon based bayesian age model for the last glacial to interglacial transition at soppensee which is used to explore synchronicity of climatic events between europe and the north atlantic local temperature changes recorded by biotic and abiotic proxies in soppensee appear to shift in phase with the oxygen isotope signal in greenland at the onset of the younger dryas however with the clarity of improved precision an apparent offset that likely results from a dating artefact is seen between records at the termination of the stadial event from a methodological standpoint the results clearly show that only by establishing detailed and independent chronological frameworks can abrupt climatic variability be compared between different regions with sufficiently high temporal precision to addresses the notion of hemispheric climatic synchronicity at the centennial scale in the late quaternary continuing to develop such approaches is therefore essential in order to understand how far in time and space the climate has behaved in such a way

holocene tephrostratigraphy of varved sediment records from lakes tiefer see ne germany and czechowskie n poland a detailed holocene tephrostratigraphic framework has been developed for two predominately varved lake sediment sequences from ne germany lake tiefer see and central n poland lake czechowskie a total of thirteen tephras and cryptotephras of icelandic provenance were detected and chemically fingerprinted in order to define correlatives and to integrate known tephra ages into the sediment chronologies out of these three cryptotephras askja ad1875 askja s and h asseldalen were identified in both records thus allowing a detailed synchronization of developing high resolution palaeoenvironmental proxy data the early holocene saksunarvatn ash layer and the middle holocene lairg b and hekla 4 cryptotephras in lake tiefer see are further important anchor points for the comparison with other high resolution palaeoclimate records in central and northern europe tentative correlations of cryptotephras have been made with a historical basaltic grimsv otn eruption ad890 e ad856 and three late holocene rhyolitic eruptions including the 2 1 ka glen garry and two unknown high silicic cryptotephras of probably icelandic provenance 1 9 cal ka bp

evolution and environmental impacts of the eruption of laacher see volcano germany 12 900 a bp abstract laacher see volcano lsv 40 km south of bonn explosively erupted ca 6 3 km 3 of chemically strongly zoned phonolite magma probably during spring 12 900 years ago the resulting eruption column having reached at least 20 km in height the bulk of the laacher see tephra lst was deposited east of the volcano within the neuwied basin lst ashes form the most important stratigraphic marker in lateglacial deposits over much of central europe a minimum of 2 mt total s was calculated to have been released during the eruption by comparing pre and posteruptive volatile concentrations in glass inclusions and pumice matrix glasses because a separate s bearing vapor phase was probably present in the magma prior to eruption as indicated by the high melt h 2 o contents close to saturation level the actual amount of s released during the eruption could have significantly exceeded 2 mt the sulfuric acid aerosol layer resulting from the massive stratospheric s input probably resided in the stratosphere for years and most likely had a significant impact on climate and thus the environment increased precipitation in central europe and or impairment of the vegetation cover for several years is suggested by several proxies especially increased sediment supply into lakes proximal to the eruptive center major environmental impacts include an initial blast that felled trees up to 4 km away from vent fast deposition of huge tephra volumes led to the complete disruption of rhine river within the lower neuwied basin and the damming up of a lake ca 140 km 2 in areal extent sudden collapse of the temporary tephra dam caused a catastrophic flood wave downstream whose deposits are recognized as far north as bonn reworking of unconsolidated tephra deposits over several 100 km 2 was widespread and extensive generating abundant lahars and flood plain deposits a braided river system established in neuwied basin probably persisted up to several years recent reports for a second eruption of lsv are not confirmed

neogene evolution of the nw european atlantic margin results from the stratagem project since the early 20th century hypothesis driven research has dominated scientific methodology anderson 2004 from a geological perspective this is well exemplified by the concept of passive continental margins so called due to their presumed relative tectonic quiescence subsequent to a phase of syn rift faulting and magmatic activity during continental break up the atlantic continental margins have long been considered as the archetype of passive continental margins the formulation of 1d stretching and cooling models has for some time determined the generalised way in which we think that such margins should behave mckenzie 1978 based on an assumption that the only significant post rift tectonic process is lithospheric cooling e g white 2003 however seismic and well data are beginning to reveal that atlantic type margins are anything but passive in their development stratigraphic and structural observations of cenozoic successions both palaeogene and neogene are beginning to reveal stepwise patterns of subsidence together with km scale tectonic uplift which cannot be accounted for by simple cooling of the lithosphere cf praeg et al 2005 and references therein

reply to comment on the paper by galaś a impact of volcanic eruptions on the environment and climatic conditions in the area of poland central europe earth science reviews vol 162 2016 58 64

icelandic volcanic ash from the late glacial open air archaeological site of ahrenshoft la 58 d north germany abstract cryptotephra of icelandic origin from the open air archaeological site of ahrenshoft la 58 d kr nordfriesland schleswig holstein northern germany overlies a late glacial havelte lithic assemblage hitherto dated by 14 c and biostratigraphy to the earliest part of the late glacial interstadial gi 1e to gi 1c 3 peaks in ash shards are observed in two profiles major and minor element geochemistry indicates volcanic ash originating in the katla system precise correlation to previously described tephra is uncertain due to overlapping chemical characteristics the ahrenshoft 14 c determinations litho and bio stratigraphy encompass a broad age span for the cryptotephra bearing sediments from the end of the allerod to the preboreal the most plausible volcanic eruption correlates are the vedde ash younger dryas already known from the european mainland tephra af555 late younger dryas and the suduroy tephra preboreal boreal hitherto recorded only in the north atlantic region these three ash horizons have been dated to respectively 12 171 57 yr b2k in the ngrip ice core c 11 500 cal bp in scotland and c 8000 cal bp by radiocarbon from the faroe isles ongoing research on deposits from the type sites for the tephra layers may in the future differentiate these markers leading to better discrimination of the chemistries and a resolution of this question

the spatial distribution of holocene cryptotephras in north west europe since 7 ka implications for understanding ash fall events from icelandic eruptions abstract we present distribution maps for all cryptotephras distal volcanic ash layers younger than 7 ka that have been reported from three or more lakes or peatlands in north west europe all but one of the tephras originates from iceland the exception has been attributed to jan mayen we find strong spatial patterning in tephra occurrence at the landscape scale most but not all of the tephra occurrences are significantly spatially clustered which likely reflects atmospheric and weather patterns at the time of the eruptions contrary to expectations based on atmospheric modelling studies tephras appear to be at least as abundant in ireland and northern scotland as in scandinavia rhyolitic and other felsic tephras occur in lakes and peatlands throughout the study region but andesitic and basaltic tephras are largely restricted to lake sites in the faroe islands and ireland explanations of some of these patterns will require further research on the effects of different methodologies for locating and characterizing cryptotephras these new maps will help to guide future investigations in tephrochronology and volcanic hazard analysis

the latest explosive eruptions of ciomadul csomad volcano east carpathians a tephrostratigraphic approach for the 51 29 ka bp time interval abstract the most recent mainly explosive eruptions of ciomadul the youngest volcano in the carpatho pannonian region have been constrained by detailed field volcanological studies major element pumice glass geochemistry luminescence and radiocarbon dating and a critical evaluation of available geochronological data these investigations were complemented by the first tephrostratigraphic studies of the lacustrine infill of ciomadul s twin craters st ana and mohos that received tephra deposition during the last eruptions of the volcano our analysis shows that significant explosive activity collectively called eppa early phreatomagmatic and plinian activity started at ciomadul in or around the present day mohos the older crater at 51 ka bp these eruptions resulted in a thick succession of pyroclastic fall deposits found in both proximal and medial distal localities around the volcano characterized by highly silicic rhyolitic glass chemical compositions ca 75 2 79 8 wt sio 2 the eppa stage was terminated by a subplinian plinian eruption at 43 ka bp producing pumiceous pyroclastic fall and flow deposits of similar glass composition probably from a proto st ana vent located at or around the younger crater hosting the present day lake st ana after a quiescent period with a proposed lava dome growth in the st ana crater a new explosive stage began defined as mpa middle plinian activity in particular a significant two phase eruption occurred at 31 5 ka bp producing pyroclastic flows from vulcanian explosions disrupting the preexisting lava dome of sf ana and followed by pumiceous fallout from a plinian eruption column related pyroclastic deposits show a characteristic less evolved rhyolitic glass composition ca 70 2 74 5 wt sio 2 and occur both in proximal and medial distal localities up to 21 km from source the mpa eruptions that may have pre shaped a crater similar to but possibly smaller than the present day st ana crater was followed by a so far unknown but likewise violent last eruptive stage from the same vent creating the final morphology of the crater this stage referred to as lspa latest st ana phreatomagmatic activity produced pyroclastic fall deposits of more evolved rhyolitic glass composition ca 72 8 78 8 wt sio 2 compared to that of the previous mpa stage according to radiocarbon age constraints on bulk sediment charcoal and organic matter from lacustrine sediments recovered from both craters the last of these phreatomagmatic eruptions that draped the landscape toward the east and southeast of the volcano occurred at 29 6 ka bp some 2000 years later than the previously suggested last eruption of ciomadul

volcanic ash layers illuminate the resilience of neanderthals and early modern humans to natural hazards marked changes in human dispersal and development during the middle to upper paleolithic transition have been attributed to massive volcanic eruption and or severe climatic deterioration we test this concept using records of volcanic ash layers of the campanian ignimbrite eruption dated to ca 40 000 y ago 40 ka b p the distribution of the campanian ignimbrite has been enhanced by the discovery of cryptotephra deposits volcanic ash layers that are not visible to the naked eye in archaeological cave sequences they enable us to synchronize archaeological and paleoclimatic records through the period of transition from neanderthal to the earliest anatomically modern human populations in europe our results confirm that the combined effects of a major volcanic eruption and severe climatic cooling failed to have lasting impacts on neanderthals or early modern humans in europe we infer that modern humans proved a greater competitive threat to indigenous populations than natural disasters

the campanian ignimbrite and codola tephra layers two temporal stratigraphic markers for the early upper palaeolithic in southern italy and eastern europe tephra layers from archaeological sites in southern italy and eastern europe stratigraphically associated with cultural levels containing early upper palaeolithic industry were analysed the results confirm the occurrence of the campanian ignimbrite tephra ci ca 40 cal ka bp at castelcivita cave southern italy temnata cave bulgaria and in the kostenki borshchevo area of the russian plain this tephra originated from the largest eruption of the phlegrean field caldera represents the widest volcanic deposit and one of the most important temporal stratigraphic markers of western eurasia at paglicci cave and lesser sites in the apulia region we recognise a chemically and texturally different tephra which lithologically chronologically and chemically matches the physical and chemical characteristics of the plinian eruption of codola a poorly known late pleistocene explosive event from the neapolitan volcanoes likely somma vesuvius for this latter we propose a preliminary age estimate of ca 33 cal ka bp and a correlation to the widespread c 10 marine tephra of the central mediterranean the stratigraphic position of both ci and codola tephra layers at castelcivita and paglicci help date the first and the last documented appearance of early upper palaeolithic industries of southern italy to ca 41 40 and 33 cal ka bp respectively or between two interstadial oscillations of the monticchio pollen record to which the ci and codola tephras are physically correlated corresponding to the greenland interstadials 10 9 and 5 in eastern europe the stratigraphic and chronometric data seem to indicate an earlier appearance of the early upper palaeolithic industries which would predate of two millennia at least the overlying ci tephra the tephrostratigraphic correlation indicates that in both regions the innovations connected with the so called early upper palaeolithic encompassing subsistence strategy and stone tool technology appeared and evolved during one of the most unstable climatic phases of the last glacial period on this basis the marked environmental unpredictability characterising this time span is seen as a potential ecological factor involved in the cultural changes observed

linking the north atlantic to central europe a high resolution holocene tephrochronological record from northern germany a high resolution holocene tephrochronology for northern germany has been established based on systematic tephrostratigraphical analysis of three peat bogs microscopic volcanic ash layers have been traced and characterised petrographically and by the chemical composition of the glass shards at least 37 ash horizons representing 16 different explosive volcanic eruptions have been identified and many can be correlated between the three sites up to 100 km apart the tephra layers can be related to icelandic volcanic sources and some correlated to the eruptions of askja 1875 hekla 3 hekla selsund hekla 4 and hekla 5 as well as to unspecified eruptions of icelandic volcanic systems e g torfajokull the source volcanoes for some tephra layers remain unidentified some tephra layers were known previously from the north atlantic region e g sluggan glen garry others have not been recorded previously in the literature e g microlite tephra this study provides the first comprehensive holocene tephrostratigraphical record for northern germany complementing the north atlantic tephrostratigraphical dating framework effectively extending it into central europe the study shows that icelandic ash layers are even more widespread than hitherto thought copyright 2002 john wiley sons ltd

new findings regarding the saksunarvatn ash in germany the saksunarvatn ash is an important tephra layer for the correlation of early holocene environmental records in northern europe the north atlantic and greenland the saksunarvatn ash is believed to have been produced by eruptions of the grimsvotn volcanic system 10 3 ka bp which had two axes of dispersal one plume in a north west direction over northern iceland and into greenland and a second southerly plume covering the faroe isles shetland isles western norway and northern germany here we present data from potremser moor north east germany extending the easterly margin of the ash fallout zone we also present single grain trace element data from the type site at saksunarvatn as well as from potremser moor the saksunarvatn ash is indistinguishable between potremser moor and saksunarvatn suggesting the two tephras were produced by the same eruption trace element compositions from both sites are similar to data from the north atlantic marine core link 14 185 but different from the grip ice core grip 1528 61 m indicating that the south east and north west plumes may have arisen from separate eruption events copyright 2013 john wiley sons ltd

extending the limits of the borrobol tephra to scandinavia and detection of new early holocene tephras analyses of two infilled lakes in blekinge southeast sweden indicate the presence of at least three tephra horizons of termination 1 and early holocene age geochemical analyses confirm the presence of the borrobol tephra the askja tephra 10 000 14c yr b p and one previously unreported tephra of icelandic origin extending the limits of the borrobol tephra to scandinavia illustrates that this ash is far more widespread than previously realized and is therefore an important marker horizon for determining the rate and timing of the initial warming at the start of greenland interstade 1 gi 1 within europe the relatively unknown askja tephra and the newly discovered hasseldalen tephra are stratigraphically placed at the younger dryas preboreal transition this paper demonstrates the suitability and success associated with the extraction techniques for tracing microtephra horizons in areas distal to volcanic sources

a tephrochronology for the lateglacial palynological record of the endinger bruch vorpommern north east germany the tephrostratigraphy of lake sediments in the endinger bruch provides the first robust age model for the lateglacial palynological records of vorpommern north east germany cryptotephra investigations revealed six tephra layers within sediments spanning from open vegetation phase i bolling 15 ka to the early holocene betula pinus forest phase pre boreal 10 5 ka four of these layers have been correlated with previously described tephra layers found in sites across europe the laacher see tephra eifel volcanic field is present in very high concentrations within sediments of the lateglacial betula pinus forest phase allerod the vedde ash iceland lies midway through open vegetation phase iii younger dryas the hasseldalen and the askja tephras iceland lie in the early holocene betula pinus forest phase preboreal these tephra layers have independently derived age estimates which have been imported into the endinger bruch record furthermore the layers facilitate direct correlation of the regional vegetation record with other palaeoenvironmental archives which contain one or more of the same tephra layers from greenland to southern europe in doing this localized variations are confirmed in some aspects of the pollen stratigraphy however transitions between the main vegetation phases appear to occur synchronously within centennial errors with the equivalent environmental transitions observed in sites across the european continent copyright 2011 john wiley sons ltd

tephrostratigraphy of a lateglacial lake sediment sequence at wegliny southwest poland abstract this paper presents the first late quaternary locality in the present day territories of poland where multiple cryptotephra layers have been identified located near wegliny in southwest poland study of the lateglacial gyttja deposits reveals the presence of at least four non visible tephra horizons electron microprobe and laser ablation icpms analysis of glass shards suggests products from at least two icelandic volcanic centres katla and snaesfellsness of particular importance is the discovery of two eruptions believed to originate from the east eifel volcanic field within the allerod chronozone one correlates with the well documented laacher see tephra lst but the second horizon herein designated t642 t655 would appear to represent an earlier precursor eruption the chemical composition of the lst and the precursor tephra both appear to match to the upper laacher see tephra ulst phase which previously was thought to have dispersed not to the northeast but in a southerly direction towards the alpine foreland this indicates the eruption dynamics of the laacher see are more complex than hitherto recognised

quantifying volcanic ash dispersal and impact of the campanian ignimbrite super eruption 1 we apply a novel computational approach to assess for the first time volcanic ash dispersal during the campanian ignimbrite italy super eruption providing insights into eruption dynamics and the impact of this gigantic event the method uses a 3d time dependent computational ash dispersion model a set of wind fields and more than 100 thickness measurements of the ci tephra deposit results reveal that the ci eruption dispersed 250 300 km 3 of ash over 3 7 million km 2 the injection of such a large quantity of ash and volatiles into the atmosphere would have caused a volcanic winter during the heinrich event 4 the coldest and driest climatic episode of the last glacial period fluorine bearing leachate from the volcanic ash and acid rain would have further affected food sources and severely impacted late middle early upper paleolithic groups in southern and eastern europe citation costa a a folch g macedonio b giaccio r isaia and v c smith 2012 quantifying volcanic ash dispersal and impact of the campanian ignimbrite super eruption geophys res lett 39 l10310 doi 10 1029 2012gl051605

a high quality annually laminated sequence from lake belau northern germany revised chronology and its implications for palynological and tephrochronological studies the annually laminated record of lake belau offers an exceptional opportunity to investigate with high temporal resolution holocene environmental change aspects of climate history and human impact on the landscape a new chronology based on varve counts 14c datings and heavy metal history has been established covering the last 9400 years based on multiple varve counting on two core sequences the easily countable laminated section spans about 7850 varve years modelled age range c 9430 to 1630 cal bp not all of the record is of the same quality but approximately 69 of the varves sequence is classified to be of high quality and only c 5 of low quality the new chronology suggests dates generally c 260 years older than previously assumed for the laminated section of the record the implications for the vegetation and land use history of the region as well as revised datings for pollen stratigraphical events are discussed tephra analysis allowed the identification of several cryptotephra layers new dates for volcanic eruptions are presented for the lairg b event c 6848 cal bp 2s range 6930 6713 cal bp the hekla 4 event c 4396 cal bp 2s range 4417 4266 cal bp and hekla 3 eruption c 3095 cal bp 2s range 3120 3068 cal bp

the roxolany tephra ukraine new evidence for an origin from ciomadul volcano east carpathians we present major element glass data and correlations for the roxolany tephra a so far geochemically unconstrained volcanic ash layer previously described in last glacial marine isotope stage 2 loess deposits of the roxolany loess palaeosol complex in south west ukraine this exceptionally well preserved 2 3 cm thick tephra layer is characterized by a rhyolitic glass composition that is comparable to that of proximal tephra units from ciomadul volcano in the east carpathians central romania the chemistry particularly matches that of the final latest st ana phreatomagmatic activity pyroclastic fall unit of st ana crater that is radiocarbon dated in the proximal mohos coring site moh 2 to 29 6 0 62 cal ka bp the age of the tephra correlative agrees with the newest radiocarbon and infrared optically stimulated luminescence age constraints from overlying palaeosols and tephra embedding loess of the roxolany sequence respectively which place the tephra between ca 33 and 24 cal ka bp and thus confirm the long debated chronostratigraphy of this important environmental archive the occurrence of a distal ciomadul tephra ca 350 km east of its source indicates great potential for further tephra and cryptotephra findings from this volcanic complex in the south eastern mediterranean and black sea region

environmental impact of the laacher see eruption at a large distance from the volcano integrated palaeoecological studies from vorpommern ne germany abstract in order to investigate the environmental impacts of the laacher see eruption 12 900 calendar years b p and the deposition of the laacher see tephra at a large distance from the volcano fine resolution micromorphological diatomological and palynological investigations were carried out on closely spaced areas in the reinberg basin vorpommern ne germany the lower part of the lst originates from atmospheric input whereas the upper part was washed in from the surrounding basin slopes diatom populations expanded as a consequence of the input of silica while simultaneously dissolution of dead diatoms decreased the tephra provided a favourable habitat for many epilithic and epipelic diatom taxa the diatoms show a slight acidification and an increase in specific conductivity of the water whereas no eutrophication is indicated these effects disappeared after lake sediments covered the tephra the pollen diagrams from the reinberg basin as well as many other pollen diagrams from ne germany indicate that the vegetation reacted to rising temperatures after the cooler gerzensee fluctuation to a short lived water level rise connected with higher precipitation after the volcanic eruption and to minor openings in the forest vegetation due to increased fire probably connected with severe thunderstorms

a regional tephrostratigraphic framework for central and southern european climate archives during the last glacial to interglacial transition comparisons north and south of the alps abstract this paper summarises the results of tephrochronological investigations into a suite of central and southern european records which include rotmeer southern germany soppensee and rotsee central swiss plateau lago di lavarone and lago piccolo di avigliana italian southern alpine foreland these sites provide records of palaeoenvironmental changes for the last glacial to interglacial transition lgit at the boundary between north atlantic and mediterranean climatic influences chemical characterisation of glass shards in volcanic ash layers indicates that multiple volcanic sources have contributed to the central european tephra record amongst other volcanic markers the laacher see tephra originating from the eifel region of germany c 12 9 0 1 ka and the vedde ash from iceland c 12 1 0 1 ka are found co located within the sediments of rotmeer soppensee rotsee and lago piccolo di avigliana these key horizons which bracket the onset of the younger dryas stadial provide precise calendrically dated tie points around which a detailed picture of the timing of local and regional environmental transitions can be constructed using the co located tephra layers the re colonisation of northern italian catchment areas by quercus is shown to occur just prior to the deposition of the laacher see tephra layer whereas to the north of the alps quercus and other thermophilous trees do not reappear until several centuries after the deposition of the vedde ash furthermore the discovery of the vedde ash in lago piccolo di avigliana and lago di lavarone is indicative of atmospheric transport of polar air into southern europe during the younger dryas stadial matching evidence proposed for such transport of polar air during the last glacial maximum lgm

a comprehensive pollen and tephra based chronostratigraphic model for the late glacial and holocene period in the french massif central this paper discusses about 250 conventional c 14 ages obtained on peat and gyttja samples that apply to pollen features or tephra beds in the massif central region of france a method to estimate the migration periods of eight late glacial to holocene pollen features typical of the massif central is described a review of all c 14 ages pertaining to tephras of this region enabled the most appropriate age or age range of the tephras to be estimated the chronostratigraphic relationships between pollen features and tephras are discussed and a new comprehensive stratigraphic model is presented the model shows that pollen features are diachronous and should not be used therefore as proxy stratigraphic markers copyright c 1996 inqua elsevier science ltd

understanding the thermal evolution of deep water continental margins areas of exploration for new hydrocarbons are changing as the hydrocarbon industry seeks new resources for economic and political reasons attention has turned from easily accessible onshore regions such as the middle east to offshore continental shelves over the past ten years there has been a marked shift towards deep water continental margins 500 2 500 m below sea level in these more hostile regions the risk and cost of exploration is higher but the prize is potentially enormous the key to these endeavours is a quantitative understanding of the structure and evolution of the thinned crust and lithosphere that underlie these margins

widespread dispersal of icelandic tephra how does the eyjafjoll eruption of 2010 compare to past icelandic events widespread dispersal of icelandic tephra how does the eyjafjoll eruption of 2010 compare to past icelandic events

two tephra layers bracketing late holocene paleoecological changes in northern germany paleoecological records from two holocene peat bogs in northern germany are linked by two microscopic volcanic ash layers correlated by petrology and geochemistry to explosive volcanism on iceland the younger microlite tephra cannot be correlated to any known eruption while the older tephra layer is identified as a deposit of the hekla 3 eruption the tephra layers are dated by an age depth regression of accelerator mass spectrometry 14c ages that have been calibrated and combined in probability distributions this procedure gives an age of 730 664 cal yr b c for the microlite tephra event and 1087 1006 cal yr b c for the hekla 3 event accordingly the tephra layers were deposited during the late bronze age at this time human settlement slowly increased pressure on the environment as indicated by changes in woodland pollen composition at the two bogs the tephra marker horizons further show that the palynologically defined transition from the subboreal to the subatlantic period is synchronous in the investigated area however the macroscopic visible marker in peat the change from fibrous to sapric peat the schwarztorf weistorf kontakt is asynchronous bog vegetation did not immediately react in unison to a climatic change at this pollen zone boundary instead the timing of vegetation change depended on the location within the bog

continued slowing of the ross ice shelf and thickening of west antarctic ice streams as part of the ross ice shelf geophysical and glaciological survey riggs ice velocities were measured on the ross ice shelf ris during 1973 78 comparisons of these with velocity estimates at the same locations derived from radarsat synthetic aperture radar sar measurements in 1997 and 2009 show velocity reduction in the southeast quadrant of the ice shelf by almost 200 m a 1 with deceleration rates increasing with time large areas of ice shelf in this region are lightly grounded forming an ice plain that increases local buttressing of the ice streams icesat measurements show this ice plain to be thickening the observed decrease in ice shelf velocities implies a total reduction in the mass of ice flowing into the ris from the west antarctic ice sheet wais by 23 gt a 1 shifting the mass balance of the wais drainage basin from strongly negative in the 1970s to strongly positive in 2009 the resulting decrease in ice advection should lead to ice shelf thinning further seaward of the ice plain this thinning would reduce the lateral drag and back stress of the shelf ice further contributing to thinning through an increase in spreading rate icesat measurements show recent thinning of most of the freely floating ice shelf

integrating the intimate records using tephrochronology rising to the challenge little has challenged our understanding of climate change more so than the abruptness with which large scale shifts in temperature occurred during the late quaternary the causal mechanisms driving

detection of the askja ad 1875 cryptotephra in latvia eastern europe we report the first geochemically confirmed findings of the askja volcano iceland ad 1875 eruption cryptotephra in eastern europe the cryptotephra finding in latvia is the easternmost finding of

constraints on the timing of quaternary volcanism and duration of magma residence at ciomadul volcano east central europe from combined u th he and u th zircon geochronology article i nfo high spatial resolutionzircon geochronologywas applied to constrain thetimescalesof volcaniceruptions of the youngest mostly explosive volcanic phase of ciomadul volcano carpathian pannonian region romania com bined u th and u th he zircon dating demonstrates that intermittent volcanic eruptions occurred in a time range of 56 32 ka the reliability of the eruption dates is supported by concordant ages obtained from different dating techniques such as zircon geochronology radiocarbon analysis and infrared stimulated luminescence dating for the same deposits the new geochronological data suggest that volcanism at ciomadul is much youn ger bca 200 ka than previously thought up to 600 ka a dominantly explosive volcanic phase occurred after an apparent lull in volcanism that lasted for several 10 s of ka after a period of lava dome extrusion that defines the onset of the known volcanism at ciomadul at least four major eruptive episodes can be distinguished within the 56 32 ka period among them relatively large sub plinian to plinian explosive eruptions produced distal tephra covering extended areas mostly southeast from the volcano the 38 9 ka tephra overlaps the age of the campanian ignimbrite eruption and has an overlapping dispersion axis towards the black sea region the wide range of u th model ages of the studied zircons indicates prolonged existence of a low temperature b800 c silicic crystal mush beneath ciomadul the main zircon crystallization period was between ca 100 and 200 ka coeval with the older mostly extrusive lava dome building stage of volcanism even the youngest u th model ages obtained for the outermost 4 m rim of individual zircon crystals predate the eruption by several 10 s of ka the zircon age distributions suggest re heating above zircon saturation temperatures via injection of hot mafic magmas prior to eruption intermittent intrusions of fresh magma could play a significant role in keeping the intrusive silicic magmatic reservoir in a partially melted for prolonged period the previous history of ciomadul suggests that melt bearing crystal mush resided beneath the volcano and was rapidly remobilized after a protracted several 10 s of ka lull in volcanism to trigger several eruptions in a comparatively short time window this classifies ciomadul as a volcano with potentially active magma storage pams which we propose to be common among the seemingly inactive volcanoes in volcanic arc regions the potential for reacti vation of these systems should be included into volcanic hazard assessments

tracing the laacher see tephra in the varved sediment record of the trzechowskie palaeolake in central northern poland abstract tephrochronological studies of partly varved sediments of trzechowskie palaeolake in central northern poland led to the finding of the late allerod laacher see tephra lst from the eifel volcanic field for the first time in a very distal site ca 840 km ene from its volcanic source the detection of glass shards of the lst involved a comprehensive combination of techniques i e biostratigraphical constrains high resolution xrf core scanning and areal xrf mapping of impregnated sediment slabs as well as detailed visual inspection of sediments the major element chemistry of volcanic glass confirmed the laacher see tephra composition in trzechowskie palaeolake sediments suggesting a deposition from the middle laacher see tephra mlst c or upper laacher see tephra ulst dispersal fans the finding of the lst in this palaeolake enables direct synchronisation with other high resolution archives in north central europe i e lake meerfelder maar rehwiese palaeolake to investigate regional variations of environmental responses at the onset of the younger dryas along a west east transect through north central europe

the late quaternary tephrostratigraphy of annually laminated sediments from meerfelder maar germany abstract the record of late quaternary environmental change within the sediments of meerfelder maar in the eifel region of germany is renowned for its high precision chronology which is annually laminated throughout the last glacial to interglacial transition lgit and most of the holocene two visible tephra layers are prominent within the floating varve chronology of meerfelder maar an early holocene tephra layer the ulmener maar tephra 11 000 varve years bp provides a tie line of the meerfelder maar record to the varved holocene record of nearby lake holzmaar the laacher see tephra provides another prominent time marker for the late allerod 200 varve years before the transition into the younger dryas at 12 680 varve years bp further investigation has now shown that there are also 15 cryptotephra layers within the meerfelder maar lgit holocene stratigraphy and these layers hold the potential to make direct comparisons between the meerfelder maar record and other palaeoenvironmental archives from across europe and the north atlantic most notable is the presence of the vedde ash the most widespread icelandic eruption known from the late quaternary which occurred midway through the younger dryas the vedde ash has also been found in the greenland ice cores and can be used as an isochron around which the gicc05 and meerfelder maar annual chronologies can be compared near the base of the annual laminations in meerfelder maar a cryptotephra is found that correlates to the neapolitan yellow tuff erupted from campi flegrei in southern italy 1200 km away this is the furthest north that the neapolitan yellow tuff has been found highlighting its importance in the construction of a european wide tephrostratigraphic framework the co location of cryptotephra layers from italian icelandic and eifel volcanic sources within such a precise chronological record makes meerfelder maar one of the most important tephrostratotype records for continental europe during the last glacial to interglacial transition