methodology of the last climatic cycle reconstruction in france from pollen data abstract a numerical method has been devised to reconstruct the climate of the last climatic cycle from pollen data reliable annual reconstructions have been published recently for the two french long sequences of la grande pile and les echets covering the last 140 millennia this paper gives more details on the method used it proposes new reconstructions based on an extended modern pollen data base these reconstructions are consistent with the previous ones especially detailed information is obtained on the seasonal characteristics of climate computations of gcm on the climate variations from 125 kyr to 115 kyr b p are confirmed for western europe the insolation variations have induced at that time a decrease of seasonality accompanied by an increased cyclonic activity in winter this has been the beginning of the first ice growth after the last interglacial other glacier growth phases are detected at the end of substage 5c and particularly at the end of substage 5a

lateral compression response of overlapping jet grout columns with geometric imperfections in radius and position spatial variability in the radius of a jet grout column is commonly encountered in practice although various prediction models for the column radius are available they have been generally used to

role of magma mixing in the pre eruptive dynamics of the aeolian islands volcanoes southern tyrrhenian sea italy abstract we combined literature and experimental data to determine the role of magma mixing in the pre eruptive dynamics of the aeolian islands volcanoes as a first step we systematically reviewed the evidence supporting the hypothesis of mixing triggered eruptions in the aeolian archipelago providing textural chemical and rheological constraints the existing data highlighted the significant role of magma mixing in many eruptions within the aeolian archipelago examples include the upper pollara and porri volcano eruptions at salina monte guardia and the ad 1230 monte pilato eruption at lipari as well as the present day activity at stromboli then we focused on vulcano island chosen as a case study because it represents one of the volcanoes posing the highest risk in the aeolian archipelago at vulcano island we highlighted the role of magma mixing in the ad 1739 and 1888 90 eruptions finally we investigated mixing to eruption timescales for the ad 1739 eruption performing mixing experiments and evaluated the progressive decay of the chemical concentration variance with time results pointed to mixing to eruption timescales of the order of 29 9 h and magma ascent rates ranging between 3 10 2 and 5 10 2 m s 1 we finally emphasized that the presented results may have significant implications in the context of volcanic hazard mitigation and planning of emergency activities

sedimentology palaeoecology and geochronology of last interglacial deposits from deeping st james lincolnshire england pollen plant macrofossil molluscan and coleopteran data from organic muds below the low terrace of the river welland at deeping st james lincolnshire indicate deposition in the mixed oak forest phase of a late pleistocene interglacial coleopteran and molluscan data suggest summer temperatures up to 4 c warmer than at present in eastern england and plant macrofossil material suggests a climate more continental than that of britain in the holocene no direct analogue of this biota however exists currently in europe biostratigraphical indications from the pollen coleoptera and mollusca suggest an age in the ipswichian interglacial thermoluminescence dates between 120 ka and 75 ka and amino acid ratios with a mean of 0 11 show that deposition of the sediments took place during oxygen isotope stage 5 this accurate dating of a partial ipswichian succession allows discussion of the ages of a number of other interglacial sites in eastern england of assumed ipswichian age copyright 1999 john wiley sons ltd

holocene recolonization and extinction of the pond turtle emys orbicularis l 1758 in europe we reconstruct the holocene range fluctuations of the european pond turtle emys orbicularis for northern and central europe based on 529 subfossil records and radiocarbon dating of critical finds we provide evidence that e orbicularis experienced a rapid range expansion with holocene warming phylogeographic data argue for a colonization of northern and central europe from a glacial refuge located in the south eastern balkans already in the late preboreal 9100 8600 cal bc the species occurred in northern central europe and was widespread in denmark and southern sweden skane during the boreal 8600 7100 cal bc the maximum range extension occurred during the holocene climatic optimum atlantic 7100 3750 cal bc with records in southern england middle sweden and northern estonia after the early subboreal 3750 1750 cal bc northern populations collapsed coinciding with a climatic cooling and oceanization northern populations were most likely established via long distance dispersal rafting using rivers debouching in the north and baltic seas after northern europe was reached a minimum dispersal of 50 km per 100 years may be hypothesized for the boreal c 2007 elsevier ltd all rights reserved

the evolution of pleistocene climate a time series approach abstract in the later part of the pleistocene variations in global ice volume have been dominated by an approximate 100 000 year cycle analysis of 2 myr long oxygen isotope record from an equatorial pacific core indicates that this is true only for the last 900 000 years prior to this time the amplitude of the 100 000 year cycle is much reduced as is the variance of all oscillations with periods greater than 60 000 years based on results of time series analysis of this 2 myr long record the pleistocene glacial cycles can be divided into three sections 1 the late pleistocene 0 900 kyr b p where the variations in the isotope record are dominated by the 100 000 year cycle 2 the middle pleistocene 900 1450 kyr b p in which low frequency components are not as important as in the later period of the pleistocene and 3 the early pleistocene late pliocene 1450 2000 kyr b p where general reductions of importance at all frequencies is seen as compared to the later intervals recent modeling efforts which describe variations in global ice volume show that the dominant low frequency component observed in the late pleistocene can result from different time constants for the rate of glacial growth and decay in response to variations in the earth s orbital parameters it is hypothesized that during the early pleistocene the rate of growth and decay of glaciers were more similar and that continental erosion by successive glacial advances lowered the land surface in areas of ice cap formation to below sea level when the ice caps became marine based more rapid decay of the ice became possible

time scales of recent phlegrean fields eruptions inferred from the application of a diffusive fractionation model of trace elements the variation of chemical element compositions in two pyroclastic sequences astroni 6 and averno 2 phlegrean fields italy is studied both sequences are compositionally zoned indicating a variability of melt compositions in the magma chamber prior to eruption a clear dichotomy between the behaviour of major vs trace elements is also observed in both sequences with major elements displaying nearly linear inter elemental trends and trace elements showing a variable scattered behaviour together with previous petrological investigations these observations are consistent with the hypothesis that magma mixing processes played a key role in the evolution of these two magmatic systems recently it has been suggested that mixing processes in igneous systems may strongly influence the mobility of trace elements inducing a diffusive fractionation phenomenon whose extent depends on the mixing time scale here we merge information from 1 numerical simulations of magma mixing and 2 magma mixing experiments using as end members natural compositions from phlegrean fields to derive a relationship relating the degree of diffusive fractionation to the mixing time scales application of the diffusive fractionation model to the two studied pyroclastic sequences allowed us to apply the relationship derived by numerical simulations and experiments to estimate the mixing time scales for these two magmatic systems results indicate that mixing processes in astroni 6 and averno 2 systems lasted for approximately 2 and 9 days respectively prior to eruption

the molluscan fauna of the cromerian type site at west runton norfolk abstract an updated and revised list of the non marine molluscs of the west runton freshwater bed wrfb the type site of the cromerian stage is presented a minimum total of 73 species is now known consisting of 46 aquatic and 27 terrestrial taxa the molluscan fauna suggests a sluggish base rich stream choked with aquatic vegetation upstream of any brackish influence the banks were bordered with marshland sandy facies with a greater proportion of fluvial species indicate more active flow within small channels four aquatic and 5 terrestrial species no longer live in the british isles and 3 6 5 of the aquatic species tanousia runtoniana borysthenia goldfussiana and pisidium clessini are extinct the cromerian molluscan fauna lacks southern thermophiles and apart from the extinct taxa is remarkably similar to modern faunas from eastern england indeed 91 of the species of aquatic mollusc found in the wrfb still inhabit east anglia a number of the species that no longer live in britain have ranges that are central or eastern european implying that the climate may have been more continental the stratigraphical ranges of both b goldfussiana and t runtoniana extend into the late early pleistocene in the netherlands and in britain they seem to occur only in temperate stage deposits falling within the early part of the cromerian complex or earlier

the mutual climatic range method of palaeoclimate reconstruction based on insect fossils new applications and interhemispheric comparisons abstract the mutual climatic range mcr method of palaeoclimate reconstruction has been employed in europe for the last decade a quantitative calibrated method mcr has many advantages over qualitative methods more recent applications deal with eastern and central north america and the method is also being developed for desert and arctic faunas the climate envelopes for north american beetles have been compiled using a 25 km gridded north american climate database that pairs climate parameters with modern collection sites modern tests of the reliability of the mcr method for north american species yielded similar results to prior european tests linear regressions of predicted on observed values yielded equations used to calibrate the mcr estimates work is under way to develop mcr estimates of mean annual precipitation for fossil assemblages from the desert southwest where moisture conditions may play a more important role in determining beetle species ranges an examination of british and north american mean july temperature reconstructions during the late wisconsinan glacial interval compares and contrasts three sets of records the north american records show no indication of the younger dryas cooling that is clearly marked in records from northwest europe the mcr method adds vigour to our reconstructions and allows us to compare between regions and with other palaeoenvironmental methods

chemical gradient at diffusive interfaces in magma chambers the results of high pressure experiments on diffusion and soret separation in natural silicate melts show that the diffusive behaviour between natural silicic and mafic magmas can be approximately modelled as if the system were a binary mixture of sio2 and other components such as mgo feo cao steady state compositional profiles across a diffusive interface between silicic and mafic magma layers are calculated on the basis of phenomenological relationships for the fluxes of chemical species and heat in the binary mixtures using the experimental data of diffusion and soret coefficients in natural silicate melts the compositional profiles show a curvature with a minimum sio2 value within the interface due to the soret effect and temperature dependence of diffusion coefficient the compositional gradient at the lower half of the diffusive interface is similar to that resulting from the soret separation of a mafic melt regardless of the composition of the silicic magmas these results suggest that picritic magma can be formed in the interfacial region between the mafic and silicic magma layers the compositional gradient explains chemical variation of mafic to picritic inclusions in a mixed andesite of the abu volcano group japan

an analysis of eemian climate in western and central europe on the basis of 31 pollen diagrams and additional data for botanical macrofossils an analysis is made of the last interglacial eemian climatic history in western and central europe the main tool for this analysis is the climatic indicator species method only selected woody species are used for the quantification of data partial climatic range diagrams are presented for abies alba acer monspessulanum acer tataricum buxus sempervirens tilia tomentosa the problem of time correlation and pollen zonation of the eemian is discussed the climatic analysis itself is based on an improved version of the indicator species method in this version not every site is analysed for its climatic values instead maps and tables on the migrational history of hedera ilex buxus abies and species of acer tilia and abies are the basis for climatic maps showing respectively january and july isotherms for the periods of the corylus zone e4a and the carpinus zone e5 it is concluded that mean january temperatures were as much as 3 c higher at amsterdam the netherlands than at present and mean temperatures in july were 2 c higher however the thermal maximum in winter was later zone e5 than the summer thermal maximum zone e4a winter temperatures changed parallel to rise and fall of global sea level precipitation changes are more difficult to estimate in the first part of the eemian precipitation must have been relatively low but from zone e4b onward it increased to higher values reaching 800 mm and probably substantially more in zones e5 and e6 hence the eemian climate was in its beginning relatively more contintental and later from e4b onward more oceanic however as compared with the holocene the eemian climate was generally speaking more oceanic

biostratigraphic and aminostratigraphic constraints on the age of the middle pleistocene glacial succession in north norfolk uk considerable debate surrounds the age of the middle pleistocene glacial succession in east anglia following some recent stratigraphical reinterpretations resolution of the stratigraphy here is important since it not only concerns the glacial history of the region but also has a bearing on our understanding of the earliest human occupation of north western europe the orthodox consensus that all the tills were emplaced during the anglian marine isotope stage mis 12 has recently been challenged by a view assigning each major till to a different glacial stage before during and after mis 12 between trimingham and sidestrand on the north norfolk coast datable organic sediments occur immediately below and above the glacial succession the oldest glacial deposit happisburgh till directly overlies the sidestrand unio bed here defined as the sidestrand hall member of the cromer forest bed formation dating of these sediments therefore has a bearing on the maximum age of the glacial sequence this paper reviews the palaeobotany and describes the faunal assemblages recovered from the sidestrand unio bed which accumulated in a fluvial environment in a fully temperate climate with regional deciduous woodland there are indications from the ostracods for weakly brackish conditions significant differences are apparent between the sidestrand assemblages and those from west runton the type site of the cromerian stage these differences do not result from contrasting facies or taphonomy but reflect warmer palaeotemperatures at sidestrand and a much younger age this conclusion is suggested by the higher proportion of thermophiles at sidestrand and the occurrence of a water vole with unrooted molars arvicola rather than its ancestor mimomyssavini with rooted molars amino acid racemisation data also indicate that sidestrand is significantly younger than west runton these data further highlight the stratigraphical complexity of the cromerian complex and support the conventional view that the happisburgh till was emplaced during the anglian rather than the recently advanced view that it dates from mis 16 moreover new evidence from the trimingham lake bed sidestrand cliff formation above the youngest glacial outwash sediments briton s lane formation indicates that they also accumulated during a middle pleistocene interglacial probably mis 11 all of this evidence is consistent with a short chronology placing the glacial deposits within mis 12 rather than invoking multiple episodes of glaciation envisaged in the new glacial stratigraphy during mis 16 12 10 and 6 copyright 2009 john wiley sons ltd

dynamics and time evolution of a shallow plumbing system the 1739 and 1888 90 eruptions vulcano island italy abstract in this work we analyze the morphology of latitic enclaves occurring in the rhyolitic lava flow of pietre cotte island of vulcano italy we show that enclave morphology is a feature inherited from the shallow plumbing system of the volcano during the invasion of the latitic magma into the rhyolitic magma the complexity of enclave morphology is quantified by fractal analyses using the empirical relationship given by perugini et al 2005 relating the fractal dimension and viscosity ratio the range of viscosity ratios that developed during the injection of the latitic magma into the rhyolitic one is estimated thermodynamical and rheological modeling indicates that the most plausible scenario to explain the variability of observed viscosity ratios is represented by a plumbing system where a large volume of latitic magma intruded a smaller volume of rhyolitic magma the comparison of volume proportions of magmas on the outcrop with those estimated by the modeling allows us to infer that most of the latitic magma remained in the plumbing system after the ending of the 1739 eruptive cycle the strong similarity of compositions from the pietre cotte lava flow and products erupted during the last volcanic activity of vulcano 1888 1890 is interpreted as the reactivation of the latitic magma that possibly evolved through fractional crystallization to produce trachy rhyolitic compositions during the 1888 1890 eruptive cycle we suggest that the methodological approach presented here can represent a further tool for hazard mitigation in volcanic areas in particular it allows obtaining information about the dynamics of plumbing systems of active volcanoes and their time evolution

comparison of element and isotope diffusion of k and ca in multicomponent silicate melts recent experimental work has shown that the homogenization of elemental concentrations can be much slower than that of isotopic ratios when there are strong concentration gradients in sio 2 and al 2o 3 the ramifications of this result for magma homogenization and other petrological problems related to diffusion are significant we report here a comparison of experimental profiles of elemental concentrations and isotopic fractions of k and ca in rhyolite andesite large concentration gradients and rhyolite rhyolite small concentration gradients melt couples when the concentration profile and the isotopic profile of the same element in a single couple are compared the former is much shorter than the latter in the rhyolite andesite couple consistent with other recent studies however the lengths of both concentration and isotopic profiles are similar in the rhyolite rhyolite couple therefore diffusion of an element or oxide may be decoupled from or coupled with isotopic diffusion depending on whether large concentration gradients of major components are present when the two couples are compared the intrinsic effective binary diffusivities obtained from isotopic profiles are similar for each element in the two couples whereas the effective binary diffusivity of k obtained from the concentration profile in the rhyolite rhyolite couple is 37 times that in the rhyolite andesite couple therefore isotopic homogenization is roughly independent of elemental homogenization and the presence of sio 2 al 2o 3 and other concentration gradients whereas elemental homogenization is strongly affected by concentration gradients our experimental data isotopic and concentration profiles including uphill diffusion profiles can be modeled quantitatively to a good approximation using a modified effective binary diffusion model in which the flux of a component is assumed to be proportional to its activity gradient instead of its concentration gradient therefore the multicomponent diffusion effect in the silicate systems of our experiments seems to be largely due to contributions of non ideal mixing to the cross terms of the diffusivity matrix

water enhanced interdiffusion of major elements between natural shoshonite and high k rhyolite melts abstract the interdiffusion of six major elements si ti fe mg ca k between natural shoshonite and a high k rhyolite vulcano island aeolian archipelago italy has been experimentally measured by the diffusion couple technique at 1200 c pressures from 50 to 500 mpa and water contents from 0 3 nominally dry to 2 wt the experiments were carried out in an internally heated pressure vessel and major element profiles were later acquired by electron probe microanalysis the concentration distance profiles are evaluated using a concentration dependent diffusivity approach effective binary diffusion coefficients for four intermediate silica contents are obtained by the sauer freise modified boltzmann matano method at the experimental temperature and pressures the diffusivity of all studied elements notably increases with dissolved h 2 o content particularly diffusion is up to 1 4 orders of magnitude faster in a melt containing 2 wt h 2 o than in nominally dry melts this effect is slightly enhanced in the more mafic compositions uphill diffusion was observed for al while all other elements can be described by the concept of effective binary interdiffusion ti is the slowest diffusing element through all experimental conditions and compositions followed by si fe mg ca and k diffuse at similar rates but always more rapidly than si and ti this trend suggests a strong coupling between melt components since effects of composition including water content are dominant a pressure effect on diffusion cannot be clearly resolved in the experimental pressure range

evolution of the fossa cone vulcano abstract in decreasing order of abundance the principal emplacement mechanisms for deposits of the fossa edifice of vulcano include dry surge wet surge pyroclastic fall lahar lava flow pyroclastic flow and epiclastic processes most samples from pyroclastic beds on fossa contain two grain size populations the coarser mode at 0 5 1 5 resulted from modified ballistic transport whereas the finer mode at 2 5 3 5 is related to surge transport reconstruction of the entire stratigraphy of the cone permits the beds to be grouped into five principal eruptive cycles all of which postdate the lower pilato ash of lipari dated at 11 000 to 8 500 y b p pte nere cycle palizzi cycle commenda cycle pietre cotte cycle and the modern cycle additional cycles may be present but exposures on the cone are insufficient for their adequate definition all cycles follow a similar stochastic pattern starting with surge eruptions and ending with effusion of lava from the crater rim the frequency of pyroclastic fall events increases with time throughout each cycle this progressive decrease in the efficiency of water melt interaction through the duration of each cycle may be due to a gradual rise of each new magma column coupled with an increase in magmatic volatiles tectonism and magma mixing both play a role in triggering eruptions on fossa the present crater lies at the intersection of two prominent tectonic trends a nnw fracture system parallels the main eruptive centers and an ene set aligns with the migration of minor vents the silicic lavas of fossa contain a mixture of two components xenocrysts of plagioclase augite and olivine surrounded by a dark glass are intimately dispersed into an evolved rhyolitic matrix

differentiation of mis 9 and mis 11 in the continental record vegetational faunal aminostratigraphic and sea level evidence from coastal sites in essex uk multidisciplinary investigations of the vegetational faunal and sea level history inferred from the infills of buried channels on the coast of eastern essex have a direct bearing on the differentiation of mis 11 and mis 9 in continental records new data are presented from cudmore grove an important site on mersea island that can be linked to the terrace sequence of the river thames the vegetational history has been reconstructed from a pollen sequence covering much of the interglacial represented the temperate nature of the climate is apparent from a range of fossil groups including plant remains vertebrates especially the rich herpetofauna molluscs and beetles which all have strong thermophilous components the beetle data have been used to derive a mutual climatic range reconstruction suggesting that mean july temperatures were about 2 c warmer than modern values for southeast england whereas mean january temperatures may have been slightly colder the sea level history has been reconstructed from the molluscs ostracods and especially the diatoms which indicate that the marine transgression occurred considerably earlier in the interglacial cycle than at the neighbouring hoxnian site at clacton there are a number of palynological similarities between the sequence at cudmore grove and clacton especially the presence of abies and the occurrence of azolla filiculoides megaspores moreover both sites have yielded palaeolithic archaeology indeed the latter is the type site of the clactonian flake and core industry however the sites can be differentiated on the basis of mammalian biostratigraphy new aminostratigraphic data as well as the differences in the sea level history the combined evidence suggests that the infill of the channel at cudmore grove accumulated during mis 9 whereas the deposits at clacton formed during mis 11 the infill of a much later channel yielding non marine molluscs and vertebrates including hippopotamus appears to have formed during the ipswichian mis 5e this evidence is compared with other important sites of late middle pleistocene age in britain and elsewhere on the continent and the importance of a multidisciplinary approach is stressed

marine isotope stage 9 environments of fluvial deposits at hackney north london uk middle pleistocene deposits at hackney north london comprise a thick unit of organic sands and silts occupying a channel near the confluence of the river thames in south eastern england and its left bank tributary the river lea they represent a short time interval perhaps no more than a few years within a late middle pleistocene interglacial the organic sediments are overlain by unfossiliferous sands and gravels indicating deposition on the floodplain of a braided river under cool or cold climatic conditions the fossil plant insect mollusc and vertebrate remains from the interglacial deposits all indicate climatic conditions with summers warmer than the present in se england and winters with a similar thermal climate the biostratigraphic evidence suggests that the time period represented by the organic unit is part of mis 9 although the geochronological evidence for such an age is inconclusive the palaeontological evidence strongly suggests that this temperate stage was warmer than the succeeding temperate stage mis 7 or the holocene and approaching the ipswichian miss 5e in its warmth the multidisciplinary description of the hackney deposits is one of the first to reconstruct terrestrial conditions in marine isotope stage 9 in western europe

the climate in western europe during the last glacial interglacial cycle derived from pollen and insect remains using the pollen sequence of la grande pile xx france we review problems with the application of transfer functions in paleoclimatic reconstructions one of them is to find modern analogues for the herbaceous vegetation of the cold periods we propose a method to distinguish between steppes and tundra vegetations for which the moderns are only partial analogues of the glacial periods another method to solve these problems is based on constraining by insect remains the two methods provide coherent reconstructions the results are also compared with other paleodata there is a good correlation with the six cold heinrich events between 70 and 15 ka b p a cooling event during the eemian period marked by high percentages of taxas at about 125 ka b p needs still to be correlated with high resolution ocean and ice cores

diffusive fractionation of trace elements by chaotic mixing of magmas abstract recent research on magma mixing systems has shown that the mixing process is governed by chaotic dynamics and that this process is responsible for the generation of fractal structures that propagate within the magmatic mass from the meter to the micrometer length scale laser ablation icp ms trace element analyses have been performed on rock samples with evidence of chaotic mixing phenomena results indicate that trace elements with similar values of diffusion coefficient display good correlations in inter elemental plots whereas as the difference between diffusion coefficients increases the correlation is progressively lost in addition a large variability of ree patterns is observed with the remarkable feature of the presence of positive and negative eu anomalies occurring at short length scale of the order of few mm given the chaotic nature of magma mixing structures the mixing process has been simulated by coupling a chaotic advection and a chemical diffusion numerical scheme by considering several trace elements with variable diffusivities simulations indicate that such a model explains with good approximation the variable correlations among trace elements observed in natural samples in addition the same patterns of ree observed in natural samples including the occurrence of positive and negative eu anomalies at short length scale are observed indicating that a chaotic advection diffusion dynamic system is a suitable model to explain natural data results presented in this contribution indicate that at the micrometric length scale small volumes of magmas are strongly influenced by the coupled action of chemical diffusion and chaotic flow fields and hence they do not represent magmas de facto present in the magmatic system because their compositions may have experienced a diffusive fractionation process these results may have important petrogenetic implications for instance if such melts were trapped as melt inclusions they would provide misleading information about melt compositions it is suggested that the approach of studying the degree of correlation among trace elements may be a possible method to test if melt inclusion compositions commonly used as petrogenetic indicators display evidence of such a diffusive fractionation process

origin of the middle pleistocene transition by ice sheet erosion of regolith the transition in the middle pleistocene 0 9 ma seen in 18o deep sea core records from relatively low amplitude high frequency 41 kyr to high amplitude low frequency 100 kyr ice volume variations under essentially the same orbital forcing can be attributed to a change from an all soft bedded to a mixed hard soft bedded laurentide ice sheet through glacial erosion of a thick regolith and resulting exposure of unweathered crystalline bedrock a one dimensional ice sheet and bedrock model which includes transport of sediment and ice by subglacial sediment deformation demonstrates that a widespread deforming sediment layer maintains thin ice sheets before the transition which respond linearly to the dominant 23 and 41 kyr orbital forcing progressive removal of the sediment layer eventually causes a transition to thicker ice sheets whose dominant timescale of change 100 kyr reflects nonlinear deglaciation processes in model simulations over the last 3 ma initialized with no ice and a uniform 50 m sediment layer the time series of ice volume and extent agree in several important aspects with the observed records

middle pleistocene interglacial thames medway deposits at clacton on sea england reconsideration of the biostratigraphical and environmental context of the type clactonian palaeolithic industry abstract in 1987 an archaeological investigation was undertaken during redevelopment of the erstwhile butlin s holiday camp at clacton on sea on the grounds that the middle pleistocene clacton channel deposits containing the type clactonian palaeolithic industry were known to extend beneath the site excavations for a storm drain allowed sampling at points along a longitudinal traverse of the main clacton channel analysis of these samples has provided new palaeontological information including data pertaining to the rise in relative sea level during the interglacial represented systematic studies of molluscs and ostracods the latter undertaken at clacton for the first time have been particularly valuable information from the butlin s site supplements evidence previously gathered from the west cliff section and from other localities at clacton the calcareous clay marl that underlies the clacton golf course extends beneath butlin s where it was found to be part of the freshwater beds not the estuarine beds as hitherto supposed the clacton estuarine beds restricted to the eastern end of the site have their base just below 2 m o d implying that their superposition upon the clacton freshwater beds occurred when relative sea level in this area was close to present ordnance datum correlation of the clacton channel deposits with the interglacial immediately following the anglian elsterian stage appears secure equivalence with oxygen isotope stage 11 of the oceanic sequence is most probable a borehole survey and subsequent excavation revealed a holocene sequence of unlithified tufa and organic sediments beneath part of the site

north atlantic intermediate to deep water circulation and chemical stratification during the past 1 myr benthic foraminiferal carbon isotope records from a suite of drill sites in the north atlantic are used to trace variations in the relative strengths of lower north atlantic deep water lnadw upper north atlantic deep water unadw and southern ocean water sow over the past 1 myr during glacial intervals significant increases in intermediate to deep 13c gradients commonly reaching 1 2 are consistent with changes in deep water circulation and associated chemical stratification bathymetric 13c gradients covary with benthic foraminiferal 18o and covary inversely with vostok co2 in agreement with chemical stratification as a driver of atmospheric co2 changes three deep circulation indices based on 13c show a phasing similar to north atlantic sea surface temperatures consistent with a northern hemisphere control of nadw sow variations however lags in the precession band indicate that factors other than deep water circulation control ice volume variations at least in this band

basalt triggering of the c ad 1305 kaharoa rhyolite eruption tarawera volcanic complex new zealand abstract the ad 1305 kaharoa eruption episode of tarawera volcanic complex was the largest 4 km3 magma eruption in new zealand in the last 1000 years high silica 76 sio2 rhyolite was erupted from seven vents along an 8 km linear zone to form pumiceous pyroclastic deposits and lava domes initial vent clearing explosions were followed by a series of plinian pumice eruptions that spread tephra downwind and pyroclastic density current deposits over the volcano slopes the early pyroclastic eruptions were followed by extrusion of a dome in the summit vent and the migration of further plinian activity to adjacent vents the episode finished with the extrusion of three summit lava domes accompanied by block and ash flows two main types of rhyolite were erupted 1 a low zr low sr high rb type comprising the early plinian pyroclastics and 2 a high zr high sr low rb type comprising the late eruptives including the summit domes basaltic material basalt and basaltic andesite is commonly present as free clasts within the kaharoa pyroclastic deposits along with rare clasts of granodiorite diorite gabbro and olivine clinopyroxenite the basaltic clasts are often veneered by kaharoa rhyolite basaltic material is also common as inclusions within rhyolite pumices along with olivine and augite xenocrysts derived from the basalt the basaltic clasts and inclusions contain complexly zoned plagioclase and corroded olivine commonly with a reaction rim consistent with disequilibrium caused by magma mixing some basaltic clasts and inclusions are hornblende free others contain groundmass hornblende plumes of brown glass often extend from hornblende bearing basaltic inclusions into the surrounding rhyolite these plumes demonstrate magma mixing as does the presence of rhyolitic glass and quartz xenocrysts in some basaltic inclusions most basaltic inclusions have crenulate boundaries suggesting they were fluidal when coming into contact with the rhyolite magma diorite gabbro and olivine clinopyroxenite clasts have mineralogy similar to the basalts commonly contain patches of fine grained basaltic material and are considered co magmatic with the basalts intrusion of basalt magma into the base of the rhyolite magma chamber appears to have occurred for some time before the kaharoa eruptions began allowing considerable mixing with the rhyolite magma transfer of water to some basalt inclusions and formation of hornblende in their groundmass conversely the hornblende free basalt inclusions did not have time to react with the rhyolite magma and must have been intruded shortly before the start of the eruption intrusion of this hornblende free basalt appears to have triggered the kaharoa eruption after the magma chamber had been primed by the earlier intrusions

constraining the recent plumbing system of vulcano aeolian arc italy by textural petrological and fractal analysis the 1739 a d pietre cotte lava flow 1 the 1739 a d pietre cotte lava flow is part of a sequence of low explosive to weak effusion events occurred at la fossa cone the active vent on vulcano island aeolian arc italy this lava is rhyolitic texturally heterogeneous and contains lati trachytic enclaves these compositions are recurrent in the la fossa volcanic products and are representative of the recent vulcano plumbing system the host lava is vesicular relatively phenocryst free and locally contains microlites and millimeter sized spherulites the enclaves are up to 10 cm in size display angular to spherical shapes and can form the core of spherulites enclaves mostly consist of plagioclase and augitic phenocrysts set in a weakly vesicular groundmass characterized by variable abundance of glass and feldspar microlites field textural and fractal data allow us to constrain the rheological features of the rhyolitic and lati trachytic magmas in situ major trace and volatile element analyses provide evidence for heterogeneities in the glassy matrix and zoning of phenocrysts processes of magma evolution have been quantitatively constrained by using the apparent distribution ratios of trace elements measured between mineral phases and glassy matrices the collected data in combination with petrological and fluid inclusion data from the literature provides evidence for 1 a genetic relationship between the two magmas through assimilation fractional crystallization process 2 a mingling mechanism between an uprising rhyolitic magma and a shallower partly crystallized lati trachytic magma plug 3 the desegregation enclaves at variable scales of the lati trachyte within the rhyolite and 4 the possible eruptive scenarios consequent to a future magmatic unrest

abrupt deglaciation events and holocene palaeoceanography from high resolution cores cartwright saddle labrador shelf canada the uppermost quaternary sediments in cartwright saddle labrador shelf are acoustically laminated with reflectors that can be traced over long distances two piston cores from the saddle record changes in sediment and meltwater delivery from the northeast margin of the laurentide ice sheet lis during deglaciation variations in sediment properties indicate a similar history of sediment accumulation over the last 12 kyr the temporal sampling interval reaches decadal resolution in the last deglacial period 7 9 ka analyses of total carbonate content sediment magnetic variables foraminiferal species and stable isotope measurements on planktic foraminifers show that abrupt changes occurred ca 10 9 9 2 8 8 7 9 and 7 ka with 450 yr correction there was no distinct change in sediment character during much of the younger dryas chronozone in the 18o record the 8 8 ka event is a dramatic 1 shift toward lower values which we associate with the noble inlet glacial event within hudson strait we do not see the pronounced low 18o event at 7 1 ka reported off nova scotia but surprisingly neither the nova scotia records nor other records in the labrador sea capture the impressive 8 8 ka change serious consideration must be given to the final collapse of the lis as the cause of the 8 2 cal ka cold event recorded in greenland and northwest europe copyright 1999 john wiley sons ltd

differentiation of the british late middle pleistocene interglacials the evidence from mammalian biostratigraphy abstract acknowledgement of the climatic complexities of the marine oxygen isotope 18o record has inspired fresh investigations into methods of identifying and separating interglacial deposits on land biostratigraphical analysis of fossil mammalian assemblages particularly those from long fluvial sequences has proved to be a uniquely valuable technique in the differentiation of the various temperate episodes of the late middle pleistocene in britain thereby enabling a sequence of diagnostic mammalian assemblage zones to be established the scheme has provided an important means of correlation between geographically distant localities and between different types of depositional environment using mammalian biostratigraphical information this paper explores the evidence for three post anglian interglacials prior to the last ipswichian interglacial correlated with stages 11 9 and 7 of the oxygen isotope record and presents the case for the recognition of much smaller scale environmental and climatic oscillations within these interglacials possibly corresponding to marine isotopic substages

trace element mobility during magma mixing preliminary experimental results abstract magma mixing tests have been performed experimentally in a taylor couette like experimental setting the variation of trace element concentrations along transects crossing the resultant melt column has been measured results indicate a strongly variable mobility of the different trace elements in the same mixing system such a different behaviour of trace elements tends to be enhanced as the mixing time increases leading to the production of highly heterogeneous volumes of melts in which depletion and enrichment of trace elements occurred depending on their potential of spreading across the magma mixing system the results presented here offer new insights into the complexity of processes expected to be operating during mixing of magmas it is demonstrated that on short mixing times also the trace elements may become highly non correlated this is due to the development of chaotic advection diffusion processes in the system these results indicate that the onset of diffusive fractionation processes may strongly influence the patterns of data on inter elemental diagrams depending on the relative mobility of the different elements

diffusion and redox reactions of sulfur in silicate melts although large scale transport in magmas is usually controlled by convection diffusion of sulfur in silicate melts nevertheless plays a crucial role in the kinetics of various magmatic processes the most important process is probably the degassing of magmas and melts initiated by an oversaturation of the melt with respect to dissolved volatiles such oversaturation can be caused in nature i e by decompression when a magma ascends to the earth surface but the degassing of melts is also of major interest for technical applications e g during fining of melts in industrial glass production the kinetics of volcanic eruptions and the fining of glass melts are basically controlled by the dynamics of bubble nucleation and growth and these properties are strongly affected by the diffusion of volatiles from the melt into bubbles nemec 1980a b sparks et al 1994 muller simon 2011 this volume hence understanding the diffusion of volatiles in melts provides a necessary tool for modeling bubble nucleation and growth however the diffusivities of volatiles such as h2o co2 so2 and h2s in the melt do not only affect the degassing rate they may also cause a fractionation of volatiles between gas phase and melt as well due to different diffusivities for instance in hydrous magmas the diffusion of h2o is usually much faster than co2 and sulfur diffusion baker et al 2005 zhang and ni 2010 so rapid disequilibrium removal of bubbles from the melt may cause an artificial enrichment of some components in the bubbles other processes which may be governed by sulfur diffusion in the melts are the dissolution and precipitation of minerals in glass manufacturing crucial problems are the kinetics of dissolution of the raw materials in the melt batch and of

land sea correlation of middle pleistocene temperate sub stages using high precision uranium series dating of tufa deposits from southern england abstract high precision u series dating allows a direct correlation to be made between terrestrial records of the penultimate interglacial marine oxygen isotope stage 7 mis 7 in britain and sub stage climate forcing in the marine oxygen isotope sequence u series ages of surficial tufa deposits are of sufficient precision to correlate discrete episodes of temperate conditions with individual warm sub stages within mis 7 furthermore detailed biostratigraphy allows periods of faunal turnover to be correlated with cold climates and lowered sea level ecological and environmental conditions in britain during mis 7 are therefore driven by the short lived sub stage climate forcing that is observable in the marine isotope record it is clear that interglacial climates are highly dynamic producing multiple climatic optima and a diverse range of environments within single warm episodes consequently sub stage records of climate forcing are crucial frameworks for reconstructing terrestrial records of environmental change

a preliminary report on the stanton harcourt channel deposits oxfordshire england geological context vertebrate remains and palaeolithic stone artefacts a summary is given of the geological faunal and archaeological information obtained during excavations in the stanton harcourt channel deposits from 1990 to 1995 the channel deposits underlie the cold climate stanton harcourt gravel member of the summertown radley terrace formation the channel sediments are attributed to oxygen isotope stage 7 when the thames was undergoing down dip migration and eroding the weymouth member of the oxford clay upper jurassic the contemporary jurassic corallian escarpment being near to stanton harcourt at that time abundant large vertebrate remains have been recovered mainly from the base of the channel deposits where a cobble and boulder bed rests on thin silt or sand horizons or in scour hollows in the clay bedrock smaller bones occur throughout the deposits which are mainly poorly sorted gravels but especially at erosive horizons several palaeolithic artefacts have been found in the same contexts many of the bones and some of the artefacts appear not to have been transported far although the artefacts cannot be linked directly with the bones a study of them adds to our knowledge of the middle pleistocene human settlement of the upper thames valley it is of interest that mammoth is abundant as part of the interglacial faunal assemblage and the significance of this is discussed the environment clearly included substantial areas of open grassland although there was also some forest in the vicinity evidence appears to be accumulating for important faunal and floral differences between particular interglacial events during the british middle and late pleistocene

assessment of a shallow magmatic system the 1888 90 eruption vulcano island italy the magmatic system feeding the last eruption of the volcano la fossa vulcano island italy was studied the petrogenetic mechanisms controlling the differentiation of erupted rocks were investigated through petrography mineral chemistry major trace and rare earth element and sr nd and pb isotopic geochemistry in addition melt inclusion and fluid inclusion data were collected on both juvenile material and xenolithic partially melted metamorphic clasts to quantify the p t conditions of the magma chamber feeding the eruption a regular and continuous chemical zoning has been highlighted rhyolites are the first erupted products followed by trachytes and latites whereas rhyolitic compositions were also found in the upper part of the sequence the chemical and isotopic composition of the rhyolites indicates that they originated by fractional crystallization from latitic magmas plus the assimilation of crustal material the trachytes represent hybrid magmas resulting from the mixing of latites and rhyolites contaminated in the shallow magmatic system the erupted products primarily compositionally zoned from latites to rhyolites are heterogeneous due to syn eruptive mingling the occurrence of magmacrust interaction processes evidenced by isotopic variations 87sr 86sr 0 70474 3 to 0 70511 3 143nd 144nd 0 512550 6 to 0 512614 8 206pb 204pb 19 318 19 489 207pb 204pb 15 642 15 782 208pb 204pb 39 175 39 613 is confirmed by the presence of partially melted metamorphic xenoliths with 87sr 86sr 0 71633 6 to 0 72505 2 and 143nd 144nd 0 51229 7 in rhyolites and trachytes afc calculations indicate a few percentage contribution of crustal material to the differentiating magmas thermometric measurements on melt inclusions indicate that the crystallization temperatures of the latites and trachytes were in the range of 1050 1100 c whereas the temperature of the rhyolites appears to have been around 1000 c at the time of the eruption compositional data on melt inclusions reveal that the magmas involved in the eruption contained about 1 1 5 wt dissolved h2o in pre eruptive conditions secondary fluid inclusions found in metamorphic xenoliths give low equilibration pressure data 30 60 mpa giving the location of the higher portions of the chamber at around 1500 2000 m of depth

past hydrographic and climatic changes in the subantarctic zone of the south atlantic the pleistocene record from odp site 1090 abstract pleistocene summer sea surface temperatures ssst have been reconstructed on a composite core section recovered in the subantarctic zone of the southern ocean from planktonic foraminifers applying the modern analog technique the composite consists of core ps2489 2 and the sections recovered at odp site 1090 and documents the last 1 83 ma three distinct climatic periods can be identified that mirror the pleistocene development of the southern ocean hydrography cold climatic conditions prevailed at 43 s during glacial as well as during interglacial periods during the early pleistocene 1 83 0 87 ma indicating a northward shift of isotherms that characterize the present day polar front zone by about 7 of latitude evidence shows a strong linkage between southern ocean and low latitude climate during that interval time between the mid pleistocene revolution ca 0 9 ma and the mid brunhes event ca 0 4 ma we observe higher amplitude fluctuations in the ssst between glacial and interglacial periods corresponding to the temperature range between the present polar front and subantarctic front these climatic variations have been related to changes in the northern hemisphere ice sheets the past 0 4 ma are characterized by strong ssst variations of up to 8 c between glacials and interglacials only during the climatic optima stages 11 3 9 3 7 5 7 1 5 5 and the early holocene ssst exceeded present ssst at the core locality 10 2 c although the carbonate dissolution record exhibits high variability during the pleistocene it can be shown that ssst estimates were not significantly biased the mid brunhes dissolution cycle as well as the mid pleistocene enhanced carbonate preservation appear to belong to a global long term variability in carbonate preservation

isotope fractionation by chemical diffusion between molten basalt and rhyolite abstract experimental diffusion couples were used to study chemical diffusion between molten rhyolite and basalt with special emphasis on the associated fractionation of calcium and lithium isotopes diffusion couples were made by juxtaposing firmly packed powders of a natural basalt suny morb and a natural rhyolite lake county obsidian and then annealing them in a piston cylinder apparatus for times ranging from 0 1 to 15 7 h temperatures of 1350 1450 c and pressures of 1 2 1 3 gpa profiles of the major elements and many trace elements were measured on the recovered quenched glasses the diffusivities of all elements except lithium were found to be remarkably similar while the diffusivity of lithium was two to three orders of magnitude larger than that of any of the other elements measured chemical diffusion of calcium from molten basalt into rhyolite was driven by a concentration ratio of 18 and produced a fractionation of 44ca from 40ca of about 6 because of the relatively low concentration of lithium in the natural starting materials a small amount of spodumene lialsi2o6 was added to the basalt in order to increase the concentration difference between basalt and rhyolite which was expected to increase the magnitude of diffusive isotopic fractionation of lithium the concentration ratio between li doped basalt and natural rhyolite was 15 and the resulting diffusion of lithium into the rhyolite fractionated 7li from 6li by about 40 we anticipate that several other major rock forming elements such as magnesium iron and potassium will also exhibit similarly larger isotopic fractionation whenever they diffuse between natural melts with sufficiently large differences in the abundance of these elements

pronounced warmth during early middle pleistocene interglacials investigating the mid brunhes event in the british terrestrial sequence the mid brunhes event mbe is a climatic transition occurring between mis 13 and 11 that separates two climatic modes 1 early middle pleistocene interglacials 780 450 ka that are characterised by only moderate warmth and 2 middle and late pleistocene interglacials occurring after 450 ka that are characterised by greater warmth consistent with or warmer than the holocene this event is observable within a variety of long climate records such as specmap and epica but its effect on terrestrial systems is poorly understood the impact of this event is examined in the british terrestrial sequence by comparing the occurrence of a range of thermophilous plant and animal species and climate reconstructions derived from assemblages containing them from interglacials of the early middle pleistocene with those from the late middle and late pleistocene this comparison reveals that interglacial climates during the early middle pleistocene in britain were as warm as and in some cases warmer than those that occurred during the late middle and late pleistocene this interpretation is supported by sea surface temperature records in the north atlantic which show that temperatures during early middle pleistocene interglacials were at least as warm as those experienced during the holocene there is therefore no evidence in climate records of britain and the north atlantic for a mid brunhes event this suggests that the mbe is not a global climatic transition but is restricted to specific regions in particular the higher latitudes of the southern hemisphere further work is needed to understand the regional variability and cause of the mbe

the viscosity of shoshonitic melts vulcanello peninsula aeolian islands italy insight on the magma ascent in dikes abstract the viscosity of shoshonitic melts and glasses from vulcanello peninsula vulcano island italy was experimentally determined at temperatures between 733 k and 1673 k the water content of the melts varies from 0 03 to 4 75 wt h 2 o the micropenetration technique was employed at ambient pressure in the high viscosity range 10 9 10 12 pa s falling sphere s experiments were performed at 500 and 2000 mpa in the low viscosity range 10 0 5 10 3 pa s results show a decrease of about 2 orders of magnitude in viscosity if 3 wt of water is added to the dry melt at 1300 k at high temperature the viscosity of vulcanello melts is intermediate between that of andesitic and basaltic melts in contrast at low temperatures 1050 k the shoshonitic melt is characterized by a lower viscosity with respect to the two previous melts the general viscosity models of giordano et al giordano d mangiacapra a potuzak m russell j k romano c dingwell d b di muro a 2006 an expanded non arrhenian model for silicate melt viscosity a treatment for metaluminous peraluminous and peralkaline liquids chemical geology 229 42 56 for dry silicate melts is in good agreement with the experimental data in the high temperature range less than 0 3 log units but shows significant differences in the low temperature range up to 1 1 log units the calculation model for hydrous silicate melts from huy and zhang huy h zhang y 2007 toward a general viscosity equation for natural anhydrous and hydrous silicate melts geochimica et cosmochimica acta 71 403 416 reproduces the new viscosity data in the high temperature range within 0 6 log units but shows as well large discrepancies in the low t range for hydrous melts deviations up to 2 log units thus we propose a specific calculation model to predict the viscosity of the shoshonitic melts as a function of temperature and water content this model reproduces the experimental data 24 measurements with a 1 standard deviation of 0 17 log units the viscosity data are used to constrain the ascent velocity of shoshonitic magmas from vulcanello within dikes using petrological data temperature and crystal content of the magma and volcanological information geometrical parameters of the eruptive fissure and depth of magma storage we estimate the time scale for the ascent of magma from the main reservoir to the surface results show time scales in the order of hours to few days we conclude that the rapid ascent of poorly evolved melts from moho depths should be taken into account for the hazard assessment of vulcano island

finite element analysis of mixed in place mip columns supporting excavations in slopes considering tension softening the use of mixed in place mip columns can be considered as an attractive alternative to sheet pile diaphragm or bored pile walls for supporting deep excavations even in difficult ground conditi

investigation of field installation effects of horizontal twin jet grouting in shanghai soft soil deposits this paper presents a case study of an investigation into the responses of the surrounding ground to the horizontal twin jet grouting method htjgm in soft soil deposits of shanghai during the fi

the grizzly lake complex yellowstone volcano usa mixing between basalt and rhyolite unraveled by microanalysis and x ray microtomography abstract magma mixing is a widespread petrogenetic process it has long been suspected to operate in concert with fractional crystallization and assimilation to produce chemical and temperature gradients in magmas in particular the injection of mafic magmas into felsic magma chambers is widely regarded as a key driver in the sudden triggering of what often become highly explosive volcanic eruptions understanding the mechanistic event chain leading to such hazardous events is a scientific goal of high priority here we investigate a mingling event via the evidence preserved in mingled lavas using a combination of x ray computed microtomographic and electron microprobe analyses to unravel the complex textures and attendant chemical heterogeneities of the mixed basaltic and rhyolitic eruption of grizzly lake in the norris mammoth corridor of the yellowstone plateau volcanic field yvf we observe evidence that both magmatic viscous inter fingering of magmas and disequilibrium crystallization dissolution processes occur furthermore these processes constrain the timescale of interaction between the two magmatic components prior to their eruption x ray microtomography images show variegated textural features involving vesicle and crystal distributions filament morphology the distribution of enclaves and further textural features otherwise obscured in conventional 2d observations and analyses although our central effort was applied to the determination of mixing end members analysis of the hybrid portion has led to the discovery that mixing in the grizzly lake system was also characterized by the disintegration and dissolution of mafic crystals in the rhyolitic magma the presence of mineral phases in both end member for example forsteritic olivine sanidine and quartz and their transport throughout the magmatic mass by a combination of both mixing dynamics and flow imposed by ascent of the magmatic mass and its eruption might have acted as a geometric perturbation of flow fields further fuelling mass exchange between magmas in terms of both chemical diffusion and crystal transfer these results illuminate the complexity of mixing in natural magmatic systems identifying several reaction related textural factors that must be understood more deeply in order to advance our understanding of this igneous process

sedimentology palaeontology and archaeology of late middle pleistocene river thames terrace deposits at purfleet essex uk middle pleistocene fluvial deposits of the corbets tey formation at purfleet essex provide evidence of an un named and previously poorly recognized interglacial thought to corrrelate with oxygen isotope stage ois 9 previous attributions of the sediments to the ipswichian last interglacial stage are refuted new investigations have yielded rich molluscan mammalian and ostracod assemblages that indicate fully temperate conditions and the distal influence of marine transgression pollen analyses suggest a previously unrecorded phase of interglacial vegetational development clast composition geomorphological evidence and the occurrence of molluscs that favour large rivers all point to deposition by the thames rather than in a minor tributary as suggested previously three separate palaeolithic industries in stratigraphical superposition are recognized at purfleet these being clactonian acheulean and levallois purfleet is therefore a key locality in the understanding of the early human occupation and exploitation of southern britain as well as for the interpretation and correlation of the terrace sequence in the thames valley

middle pleistocene interglacial deposits at barling essex england evidence for a longer chronology for the thames terrace sequence results are presented from a multidisciplinary study of fossiliferous interglacial deposits on the northern side of the thames estuary these fill a channel cut into london clay bedrock and overlain by the barling gravel a thames medway deposit equivalent to the lynch hill and corbets tey gravels of the middle and lower thames respectively the channel sediments yielded diverse molluscan and ostracod assemblages both implying fully interglacial conditions and a slight brackish influence pollen analysis has shown that the deposits accumulated during the early part of an interglacial plant macrofossils particularly the abundance of trapa natans reinforce the interglacial character of the palaeontological evidence a beetle fauna which includes four taxa unknown in britain at present has allowed quantification of palaeotemperature using the mutual climatic range method tmax 17 to 26 c tmin 11 to 13 c a few vertebrate remains have been recovered from the interglacial deposits but a much larger fauna as well as palaeolithic artefacts is known from the overlying barling gravel the age of the interglacial deposits is inferential the geological context suggests a late middle pleistocene interglacial part of the post diversion thames system and therefore clearly post anglian this conclusion is supported by amino acid ratios from the shells of freshwater molluscs the correlation of the overlying barling gravel with the lynch hill corbets tey aggradation of the thames valley constrains the age of the barling interglacial to marine oxygen isotope stages 11 or 9 the presence of corbicula fluminalis and pisidium clessini confirms a pre ipswichian marine oxygen isotope substage 5e age and their occurrence in the early part of the interglacial cycle at barling precludes correlation with marine oxygen isotope stage 11 as these taxa occur only later in that interglacial at sites such as swanscombe and clacton thus by process of elimination a marine oxygen isotope stage 9 age would appear probable

a field trial of jet grouting in marine clay the basement excavation of the singapore post center involved extensive jet grouting to improve the soft marine clay present within the excavation the treated soil mass with much improved strength and deformation characteristics was intended to act as an internal strut below the bottom of the excavation level reducing movements caused by the basement excavation this paper presents the performance of a well instrumented field jet grouting trial during the construction of the building basement results of monitoring suggest that the jet grouting trial caused the retaining diaphragm walls and the adjacent soils immediately behind and at some distance away from the walls to move away from the jet grouted area the maximum free field lateral soil movements in the excavation side of the jet grouted mass were much larger than the corresponding lateral movements behind the wall the results suggest that the diaphragm wall provided considerable restraint thereby reducing the lateral movements of the soil beh

the chronology palaeogeography and archaeological significance of the marine quaternary record of the west sussex coastal plain southern england u k abstract the quaternary sediments of the west sussex coastal plain have produced a wide range of floral faunal and archaeological remains these sediments consist of marine sands and gravels exhibiting transgressive and regressive trends which occur from present day sea level to c 43 0 m o d and are overlain by terrestrial silts and cold climate periglacial sediments at the present day coastline channel fill deposits occur below modern beach levels new field observations coupled with a re investigation of old sites and literature suggest that five discrete high stands of sea level may be preserved in the area of the west sussex coastal plain age estimates for these deposits suggest that they span large parts of the middle and upper pleistocene oxygen isotope stages 13 to 5 conformable relationships between many of the marine and terrestrial sediments suggest that the potential exists within the area to correlate the marine and terrestrial quaternary stratigraphic records in addition sediments associated with two of these high sea level stands are associated with extensive buried landsurfaces covering large areas of the coastal plain at some locations these intact landsurfaces are associated with evidence for human activity and represent stratigraphic and cultural resources of international importance

volcanological and petrological evolution of vulcano island aeolian arc southern tyrrhenian sea petrological and geochemical data are reported for volcanic rocks from vulcano island the subaerial volcanism 120 ka to present built up a nw se elongated composite structure affected by two intersecting multistage calderas volcanics older than 20 ka consist mostly of high k calc alkaline hkca to shoshonitic sho mafic rocks these magmas interacted significantly with the continental crust which generated variable sr isotopic ratios 0 70412 0 70520 however a major role was also played by input of parental liquids into the magma chamber which prevented further evolution of the magmas hkca sho and potassic ks rocks formed from 20 to 8 ka display a much larger range of sio2 from shoshonites to rhyolites and higher concentrations of incompatible elements with respect to the previous stage sr isotopic ratios show small variations 0 70448 0 70486 mixing of silicic and mafic liquids and fractional crystallization processes fc were the main evolutionary processes during this stage volcanics younger than 8 ka consist of sho and leucite bearing ks mafic rocks with abundant intermediate and silicic products mafic and intermediate rocks display similar incompatible element abundances and sr isotopic ratios as the previous stage volcanics whereas higher 87sr 86sr 0 70494 0 70583 are observed in some rhyolites these products originated from a complex interplay of fc crustal assimilation and magma mixing processes the most mafic rocks show increasing incompatible element abundances rb sr rb ba mg al mg ca and a decrease in large ion lithophile to high field strength element ratios passing from older hkca sho to the younger sho ks volcanics these variations suggest a shifting of magma sources from a slightly metasomatized asthenosphere fertile peridotite to a more strongly metasomatized lithospheric mantle residual peridotite time related petrological and geochemical variations have been used to develop a model for the evolution of the vulcano plumbing system