fossils from quaternary fluvial archives sources of biostratigraphical biogeographical and palaeoclimatic evidence fluvial sedimentary archives have the potential to preserve a wide variety of palaeontological evidence ranging from robust bones and teeth found in coarse gravel aggradations to delicate insect remains and plant macrofossils from fine grained deposits over the last decade advances in quaternary biostratigraphy based on vertebrate and invertebrate fossils primarily mammals and molluscs have been made in many parts of the world resulting in improved relative chronologies for fluviatile sequences complementary fossil groups such as insects ostracods and plant macrofossils are also increasingly used in multi proxy palaeoclimatic and palaeoenvironmental reconstructions allowing direct comparison of the climates and environments that prevailed at different times across widely separated regions this paper reviews these topics on a regional basis with an emphasis on the latest published information and represents an update to the 2007 review compiled by the flag inspired igcp 449 biostratigraphy subgroup disparities in the level of detail available for different regions can largely be attributed to varying potential for preservation of fossil material which is especially poor in areas of non calcareous bedrock but to some extent also reflect research priorities in different parts of the world recognition of the value of biostratigraphical and palaeoclimatic frameworks which have been refined over many decades in the core regions for such research particularly for the late middle and late pleistocene of nw europe has focussed attention on the need to accumulate similar palaeontological datasets in areas lacking such long research histories although the emerging datasets from these understudied regions currently allow only tentative conclusions to be drawn they represent an important stage in the development of independent biostratigraphical and palaeoenvironmental schemes which can then be compared and contrasted

significance of the record provided by pleistocene fluvial deposits and their included molluscan faunas for palaeoenvironmental reconstruction and stratigraphy case studies from the english midlands abstract the vast majority of pleistocene fluvial deposits in northwest europe are of cold climate origin with the most important sediment type being coarse sands and gravels formed under nival regimes less commonly sands and silts of interglacial deposition are preserved in the lower levels of major aggradations or in channels preserved beneath them molluscan faunas are common in both types of deposit although the fine grained temperate sediments show the best preservation and the most diverse assemblages this paper will discuss the types of molluscan faunas found in fluvial deposits and assess their suitability for both climatic reconstruction and stratigraphic studies while it has been clear for many years that reliable local environmental reconstructions can be made using mollusca they have been less used for regional climatic assessment work in england over the past thirty years shows that faunas obtained from fluvial sediments particularly if they contain both freshwater and terrestrial species can provide a basis for regional climatic reconstruction mollusca may also allow the separation from each other of interglacials and interstadials and permit these episodes to be more precisely defined than is allowed by other means such as palynology molluscan faunas may offer potential for the identification of temperature episodes which may have the same climatic status as interglacials but which are not recognised as such by other palaeontological evidence such as pollen the use of molluscan faunas for biostratigraphy has been firmly rejected by previous authors however recent work concentrating on sites of similar facies within single catchments has shown that both presence and absence of individual species particularly those now exotic to the british isles e g belgrandia marginata michaud and corbicula fluminalis muller can be a useful guide to relative age examples illustrating the significance of these faunas in the stratigraphic record are largely taken from the fluvial deposits of the major rivers of the english midlands warwickshire avon great ouse nene but reference is also made to other studies on the deposits of the thames the ages of the faunas described range from the cromerian interglacial to the devensian glacial stage and includes data from sites in integlacials identified in the stratigraphic record but so far not formally named

late middle pleistocene interglacial deposits at upper strensham worcestershire england pleistocene deposits containing the disarticulated skeleton of a mammoth and associated faunal and floral remains were discovered in july 1990 at upper strensham worcestershire the environmental evidence from the fauna and flora together with limited geological evidence indicates that the deposits accumulated within a low energy fluvial environment with a surrounding marsh and restricted tree cover on or close to the floodplain the patchy occurrence of trees in a species rich grassland is discussed and the climatic significance of the fauna and flora is considered the strensham site lies within the valley of the river avon which is known to contain at least five altitudinally distinct river terraces the deposits at strensham lie beneath a terraced surface that cannot be accommodated within the existing framework of terrace development in the valley and evidence is presented which may suggest that these deposits form a previously unrecognised fluvial unit the strensham member of the avon valley formation amino acid age estimates from shells taken from the fossiliferous sediments of the strensham member suggest a correlation with oxygen isotope stage 7 this correlation suggests that the temperate deposits at this site should be correlated with the temperate phase recorded at marsworth buckinghamshire and stoke goldington in the vafley of the great ouse journal of quaternary science

mammalian evidence from middle pleistocene fluvial sequences for complex environmental change at the oxygen isotope substage level abstract mammalian remains have proved to be a uniquely valuable tool in differentiating between the various temperate episodes of the late middle pleistocene in britain long fluvial records such as that of the river thames have provided a template against which the mammalian biostratigraphical evidence may be tested thereby enable a sequence of diagnostic mammal biozonations to be established the mammalian evidence also identifies much smaller scale environmental and climatic oscillations within these interglacials possibly corresponding to isotopic substages this paper reviews in detail two sites in the lower thames valley swanscombe and aveley attributed to mis 11 and mis 7 respectively and presents the mammalian evidence for climatic complexity and habitat succession within these interglacials

palaeontology and taphonomy of late quaternary fossil assemblages at somersham cambridgeshire england and the problem of reworking assemblages of foraminifers ostracods and molluscs from temperate ipswichian stage last temperate stage sediments and overlying cold devensian stage last cold stage sediments at somersham in the southern fenland of cambridgeshire have been analysed the ipswichian sediments contain faunas consistent with temperate brackish water conditions under tidal influence the devensian assemblages were recovered from a series of sands and gravels laterally accreting in a channel cutting into ipswichian sediments in contrast to the ipswichian faunas the faunas of particular devensian samples show a complex mixture of temperate freshwater brackish and marine taxa the molluscs are mainly freshwater with few land snails they occur together with foraminifers and ostracods freshwater brackish water and marine ostracods are present with foraminifers a sample of devensian fine laminated sediment in the channel was analysed for pollen only abundant pre quaternary spores were present with abundant foraminifers in the same sample the taphonomy of the assemblages and the difficulties of their interpretation in environmental terms are discussed the importance of taphonomy in assessing environments climate range of taxa and dating is stressed

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

eight glacial cycles from an antarctic ice core the antarctic vostok ice core provided compelling evidence of the nature of climate and of climate feedbacks over the past 420 000 years marine records suggest that the amplitude of climate variability was smaller before that time but such records are often poorly resolved moreover it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records here we report the recovery of a deep ice core from dome c antarctica that provides a climate record for the past 740 000 years for the four most recent glacial cycles the data agree well with the record from vostok the earlier period between 740 000 and 430 000 years ago was characterized by less pronounced warmth in interglacial periods in antarctica but a higher proportion of each cycle was spent in the warm mode the transition from glacial to interglacial conditions about 430 000 years ago termination v resembles the transition into the present interglacial period in terms of the magnitude of change in temperatures and greenhouse gases but there are significant differences in the patterns of change the interglacial stage following termination v was exceptionally long 28 000 years compared to for example the 12 000 years recorded so far in the present interglacial period given the similarities between this earlier warm period and today our results may imply that without human intervention a climate similar to the present one would extend well into the future

geology and impact features of riachao structure northern brazil abstract riach ao located at s7 42 w46 38 in maranh ao state northeastern brazil is acomplex impact structure of about 4 1 km diameter formed in pennsylvanian to permiansedimentary rocks of the parnaiba basin sequence although its impact origin was alreadyproposed in the 1970s information on its geology and shock features is still scarce in theliterature we present here the main geomorphological and geological characteristics of theriach ao impact structure obtained by integrated geophysical and remote sensing analysis aswell as geological eld work and petrographic analysis the identi ed lithostratigraphicunits consist of different levels of the pedra de fogo formation and possibly the piauiformation our petrographic analysis con rms the presence of shock diagnostic planarmicrodeformation structures in quartz grains of sandstone from the central uplift asevidence for an impact origin of the riach ao structure the absence of crater lling impactbreccias and melt rocks shatter cones as well as the restricted occurrence of microscopicshock effects suggests that intense and relatively deep erosion has occurred since craterformation introductionthe riach ao structure centered at s7 42 sandw46 38 is located in a remote area of maranh ao statein northern brazil fig 1 it was recognized as ameteorite impact structure by mchone 1986 based onevidence of breccia occurrences and planar fractures inquartz but no diagnostic data such as bona de planardeformation features pdf were found at that time besides riach ao there are another ve con rmedimpact structures in brazil araguainha 40 kmdiameter varge ao 12 4 km vista alegre 9 5 km serra da cangalha 13 7 km and santa marta 12 km two other possible impact structures in thebrazilian territory are cerro do jarau 13 5 km andcol onia 3 6 km riccomini et al 1991 2011 cr osta2004 crosta et al 2010 crosta and vasconcelos 2013 uchoa et al 2013 the riach ao structure is a regionally anomalous somewhat circular area of highly deformed rocks of4 1 km diameter the whole structure is seeminglydeeply eroded in a region of at lying undeformedsedimentary rocks these sedimentary strata belong tothe carboniferous to permian sequences of the balsasgroup of the parnaiba basin fig 2 the rst reference to the circular structure atriach ao was made by ojeda and bembom 1966 these authors during an oil exploration projectconducted by petrobras a brazilian oil company during the 1960s and 1970s described the anomalousradial drainage pattern formed by the sereno river andits tributaries as for the possible origin for this

evidence for the early onset of the ipswichian thermal optimum palaeoecology of last interglacial deposits at whittlesey eastern england fossiliferous deposits infilling a channel at whittlesey eastern england are dated by amino acid racemization to the last interglacial and pollen analysis indicates deposition in ipswichian biozones ip ib and ip iib multidisciplinary palaeoenvironmental analyses of these deposits provide a rare insight into ip ib subzone conditions specifically the ip ib deposits contain exotic thermophiles naias minor belgrandia marginata bembidion elongatum pelochares versicolor caccobius schreberi onthophagus massai and emys orbicularis usually associated with ip iib combined palaeotemperature reconstructions based on beetle ostracod and vertebrate assemblages of the ip ib deposits indicate that summers mean july range 19 to 22 c were at least 2 c warmer than at present whereas winters mean january air temperature range 0 to 7 c were probably similar to those of today these palaeotemperature ranges encompass those for ip iib deposits at trafalgar square 20 to 21 c and 1 5 to 3 c previously considered the only ipswichian site to record temperatures significantly warmer than holocene temperatures of particular significance is that thermal optimal conditions commenced in ip ib rather than being confined to ip iib this demonstrates rapid warming and biological response to early ipswichian climate amelioration which accords with the deep sea last interglacial and european eemian records supplementary material supplementary tables s1 s7 are available at http doi org 10 6084 m9 figshare c 3830221

late pleistocene deposits at block fen cambridgeshire england organic sediments in a gravel quarry at block fen cambridgeshire form a sheet dividing lower from upper gravels analyses of pollen macroscopic plant remains and molluscs from these organic sediments are presented they indicate the presence of temperate freshwater and slightly brackish fine floodplain sediments which on the basis of the palaeobotany are correlated with the temperate ipswichian stage the freshwater sediments ascribed to ipswichian substage iib occur at ca 3 m od marine influenced tidal sediments ascribed to ipswichian substage iii occur at ca 6 m od no evidence was found for the presence of more than one temperate stage in the sequence the lower gravels are then correlated with the cold wolstonian stage and the upper gravels with the cold devensian stage in contrast to the woodland environments indicated by the palaeobotany of the ipswichian organic sediments post ipswichian pollen diagrams and macroscopic plant remains in the upper suite of sands and gravels indicate open tree less vegetation typical of the cold devensian stage they also contain a typical cold stage mollusc fauna the sediments containing these floras and faunas are associated with thermal contraction cracks indicating the presence of permafrost the final sand and gravel aggradation in the devensian forms the block fen terrace near 0 m od the evidence indicates that it is younger than the lacustrine sediments resulting from the blocking of the fenland at the wash by late devensian ice at ca 18 5 ka bp the sequence at block fen is related to nearby ipswichian and devensian sediments at chatteris march wimblington and mepal and to deposits at wretton on the east margin of fenland the correlation permits an outline reconstruction of the history of the valley carrying the river great ouse between the isle of ely and the chatteris and march islands from the time of a gravel aggradation before the ipswichian to the flandrian the reconstruction shows the time and level of the ipswichian marine incursion into the middle level of fenland and the extent of aggradation and erosion in the devensian

mollusca from last interglacial fluvial deposits of the river thames at trafalgar square london an account is given of the molluscan assemblages recovered from fluvial deposits beneath the upper floodplain terrace of the river thames in the vicinity of trafalgar square central london a total of 37 aquatic and 28 terrestrial taxa have been recorded a diversity indicative of full interglacial conditions palaeobotanical and vertebrate evidence suggests that these fossiliferous sediments belong to the last ipswichian interglacial a conclusion strongly supported by molluscan evidence the combination of the presence of certain species such as belgrandia marginata potomida littoralis and margaritifera auricularia together with the absence of other taxa that no longer live in britain such as pisidium clessini corbicula fluminalis and unio crassus imparts a distinctive character to the fauna these temperate molluscs were not only present in the trafalgar square sands and silts but also in the underlying spring gardens gravel showing the latter to be an interglacial aggradation that did not accumulate during the late wolstonian contrary to previous interpretations copyright 1999 john wiley sons ltd

a chronological framework for the british quaternary based on bithynia opercula the british quaternary spanning roughly the past 2 6 million years is unmatched for the biodiversity and abundance of its fossil localities and its record of climatic contrasts however with all but the most recent deposits beyond radiocarbon range and with no readily datable volcanic rocks it has been difficult to get accurate dates for many british pleistocene deposits penkman et al have developed new analytical methods based on the intra crystalline proteins of stable biominerals in the opercula shell closure of the freshwater gastropod bithynia common in quaternary deposits they obtain confident assignments for various strata to global marine isotope stages securely placing britain s rich record of faunal and archaeological change into a broader context marine and ice core records show that the earth has experienced a succession of glacials and interglacials during the quaternary last 2 6 million years although it is often difficult to correlate fragmentary terrestrial records with specific cycles aminostratigraphy is a method potentially able to link terrestrial sequences to the marine isotope stages mis of the deep sea record1 2 we have used new methods of extraction and analysis of amino acids preserved within the calcitic opercula of the freshwater gastropod bithynia to provide the most comprehensive data set for the british pleistocene based on a single dating technique a total of 470 opercula from 74 sites spanning the entire quaternary are ranked in order of relative age based on the extent of protein degradation using aspartic acid asparagine asx glutamic acid glutamine glx serine ser alanine ala and valine val this new aminostratigraphy is consistent with the stratigraphical relationships of stratotypes sites with independent geochronology biostratigraphy and terrace stratigraphy3 4 5 6 the method corroborates the existence of four interglacial stages between the anglian mis 12 and the holocene in the terrestrial succession it establishes human occupation of britain in most interglacial stages after mis 15 but supports the notion of human absence during the last interglacial mis 5e 7 suspicions that the treeless optimum of the upton warren interstadial at isleworth pre dates mis 3 are confirmed this new aminostratigraphy provides a robust framework against which climatic biostratigraphical and archaeological models can be tested

luminescence dating indicates radiocarbon age underestimation in late pleistocene fluvial deposits from eastern england robust geochronological control is crucial for interpreting and correlating the environmental record from fragmentary terrestrial sequences from the last glacial period traditional terrestrial stratigraphies are typically reliant on radiocarbon dating although estimates of antiquity for samples older than 40 ka may be unreliable optically stimulated luminescence osl dating of sediments is an alternative for dating the whole of the last glacial period and also provides the opportunity to independently test radiocarbon based chronologies this paper presents a set of nine directly comparable paired osl and accelerator mass spectrometry ams radiocarbon ages from multiple sites within devensian fluvial sediments in lowland britain and shows that it is possible to obtain robust osl age estimates throughout this time period the two techniques agree well for ages younger than ca 29 14c ka bp ca 35 cal ka bp but disagree beyond ca 35 14c ka bp ca 40 cal ka bp this is thought to be due to radiocarbon ages on older organic material having been contaminated by low levels of modern carbon it is therefore suggested that all conventionally pre treated radiocarbon ages greater than 35 14c ka bp should be treated with extreme caution copyright 2009 john wiley sons ltd

late middle pleistocene pollen biostratigraphy in britain pitfalls and possibilities in the separation of interglacial sequences abstract recent work on late middle pleistocene interglacials in britain has shown that sites formerly attributed to the hoxnian include representatives of two different interglacials which have been correlated with oxygen isotope stages 11 and 9 palynology has long been used to characterize and correlate temperate sequences in britain however the quality of the palynological record is considerably better in lacustrine sequences than in fluvial and estuarine sediments the former have longer sequences and higher resolution whereas more rapid deposition in fluvial and estuarine environments leads to sequences representing only fragments of interglacials the latter type of site however is more likely to have multi proxy evidence and to be readily fitted into a stratigraphical framework the problems are reviewed in the light of new work in the west midlands where some of the most complete british late middle pleistocene lacustrine sequences are preserved lacustrine sites here have a strong affinity with hoxnian sites of the type area in east anglia a critical question remains as to whether the two interglacials conflated under the term hoxnian can be separately characterized in terms of their pollen assemblages details of lacustrine sequences in the north birmingham area and east anglia show remarkable similarities perhaps suggesting that the same interglacial is recorded in all of them as many of these sites are thought to be kettle holes or glacially overdeepened basins the first interglacial following the anglian glaciation is the most likely to be represented suggesting that all the lacustrine hoxnian sites might date from ois 11 in areas not glaciated since the anglian interglacials after ois 11 are likely to be represented only by fragmentary non lacustrine sequences difficult if not impossible to separate using palynology alone

a late middle pleistocene temperate periglacial temperate sequence oxygen isotope stages 7 5e near marsworth buckinghamshire uk abstract river channel and colluvial deposits near marsworth buckinghamshire record a temperate periglacial temperate sequence during the late middle pleistocene the deposits of a lower channel contain tufa clasts bearing leaf impressions that include acer sp and sorbus aucuparia and containing temperate arboreal pollen attributed to ash dominated woodland the tufa probably formed at the mouth of a limestone spring before being redeposited in a small river whose deposits contain plant remains mollusca coleoptera ostracoda and vertebrate bones of temperate affinities the sediments sedimentary structures and limited biological remains above the lower channel deposits indicate that fluvial deposition preceded climatic cooling into periglacial conditions fluvial deposition recurred during a later temperate episode as shown by the mammalian bone assemblage in stratigraphically higher channel deposits the upper channel deposits are confidently attributed to oxygen isotope sub stage 5e ipswichian on the basis of their vertebrate remains however the age of the lower channel deposits is less clear the mammalian and coleopteran remains in the lower channel strongly suggest correlation with oxygen isotope stage 7 on the basis of their similarities to other sites whose stratigraphy is better known and the clear difference of the lower channel assemblage from well established faunas of ipswichian or any other age by contrast u th dating of the tufa clasts suggests an age post 160 ka bp while aile ile ratios on mollusca point to an ipswichian age and younger four ways of interpreting this age discrepancy are considered the preferred one correlating the lower channel deposits with oxygen isotope stage 7

the late middle pleistocene biostratigraphy of the thames valley england new data from eastern essex abstract coring investigations at east hyde near tillingham essex have revealed a sequence of fluvial and estuarine deposits infilling a channel incised into london clay these deposits are of thames origin and were deposited after the river s diversion into eastern essex late in the anglian stage the detailed litho and biostratigraphy of the deposits are described ostracod and molluscan data confirm that the lower parts of the sequence accumulated in a quiet fluvial environment rich in aquatic vegetation the upper sediments accumulated in an inner estuarine environment under conditions of rising sea level pollen assemblages from both units show strong biostratigraphical affinities with the hoxnian stage particularly with the hoxnian late temperate substage ho iii the sequence has also yielded a rare assemblage of freshwater fluvial molluscs the rhenish fauna which migrated into the thames following a link with the rivers of continental europe the occurrence of theodoxus serratiliniformis is exceptionally rare representing only the second record of the species in the entire british pleistocene the molluscan assemblages show striking similarities with those at clacton in northeast essex and swanscombe kent and provide strong evidence that the three sites are contemporaneous and were connected in the same fluvial system the timing of the migration of the rhenish fauna into britain and the implications for sea level reconstruction in the southern north sea region are discussed the episode of major climatic warmth and high eustatic sea level represented at east hyde is correlated with stage 11 of the deep sea record

middle to late pleistocene palaeoecological reconstructions and palaeotemperature estimates for cold cool stage deposits at whittlesey eastern england fossiliferous beds in a complex sequence of late middle to late pleistocene deposits at whittlesey eastern england provided a rare opportunity for a multidisciplinary study of the palaeoecology of cool cold stage deposits from different glacial stages the fossiliferous sediments investigated form part of the river nene 1st terrace three of the four fossil assemblages investigated pre date the last interglacial stage ipswichian eemian marine oxygen isotope stage mis 5e whereas the other dates to part of the mis 3 interstadial complex middle devensian weichselian pollen plant macrofossil molluscan coleopteran ostracod foraminifera and vertebrate data are available to a greater or lesser extent for each cool cold stage assemblage and they broadly present the same ecological picture for each one a continuum from low energy permanent to non permanent aquatic habitats through marshland with associated waterside taxa together with flood influxes of fluvial riparian and ruderal taxa although each fossil assemblage records cool cold climatic conditions to a greater or lesser extent these conditions are more apparent in the insect and ostracod faunas in comparison with results published for the last glacial maximum lgm stadial in the netherlands palaeotemperature estimates based on ranges of mutual agreement between independent coleopteran and ostracod methods for the three pre ipswichian eemian assemblages indicate minimum mean july air temperatures that are from 1 to 3 c warmer but january values that embrace the 8 c estimate for the lgm there is however a disparity between the coleopteran and ostracod palaeotemperature estimates for the middle devensian weichselian fossil assemblage which are based on two different sample stratigraphic levels the lower coleopteran assemblage is indicative of very cool continental climates whereas the stratigraphically slightly higher ostracod assemblage suggests a climatic amelioration lack of numerical age estimates prevents a robust stratigraphical interpretation but the youngest pre ipswichian eemian fossil assemblage could date to the mis 7 6 transition at a time when cooling possibly preceded glacially driven sea level fall it is apparent from the rich coleopteran data that some continental cold indicator taxa also appeared in pre ipswichian eemian cold stages and therefore assignment of continental cold indicator taxa to particular devensian weichselian intervals should be undertaken with care

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

the complex impact structure serra da cangalha tocantins state brazil abstract serra da cangalha is a complex impact structure with a crater diameter of 13 700 m and a central uplift diameter of 5800 m new findings of shatter cones planar fractures feather features and possible planar deformation features are presented several ring like features that are visible on remote sensing imagery are caused by selective erosion of tilted strata the target at serra da cangalha is composed of devonian to permian sedimentary rocks mainly sandstones that are interlayered with siltstone and claystones nne ssw and wnw ese striking joint sets were present prior to the impact and also overprinted the structure after its formation as preferred zones of weakness these joint sets partly controlled the shape of the outer perimeter of the structure and in particular affected the deformation within the central uplift joints in radial orientation to the impact center did not undergo a change in orientation during tilting of strata when the central uplift was formed these planes were used as major displacement zones the asymmetry of the central uplift with preferred overturning of strata in the northern to western sector may suggest a moderately oblique impact from a southerly direction buckle folding of tilted strata as well as strata overturning indicates that the central uplift became gravitationally unstable at the end of crater formation

palaeoecology of a late mis 7 interglacial deposit from eastern england a multidisciplinary investigation was undertaken to establish the palaeoecology of three different fluvial depositional environments in the basal sediments of a richly fossiliferous channel infill at whittlesey eastern england which is dated by amino acid racemization aar to marine oxygen isotope stage mis 7 molluscan and coleopteran data indicate that the river flowed throughout the year supporting extensive adjacent marshland palaeobotanical and insect evidence indicates that extensive deciduous woodland was present and the ostracod evidence indicates that saline habitats were available locally suggesting that sea level at the time was not much different to today pollen and insect data do not differentiate thethree different depositional environments in contrast to the molluscan and ostracod evidence temperature estimates based on insect and ostracod data indicate a mutual mutual mean july temperature of 16 21 c and 1 to 3 c for january this is the first fully interglacial fluvial fossil assemblage described so far for the river nene catchment that is reliably dated to mis 7 of particular note is the molluscan assemblage which contains eight exotic species including theodoxus danubialis a species described previously in the united kingdom only in mis 11 deposits associated with the river thames catchment also of note is the insect assemblage which in contrast contains no exotic species unlike other mis 7 insect assemblages recorded so far in the united kingdom together these faunal assemblages may suggest a hitherto uninvestigated phase of a british interglacial stage which the aar data indicate could be late in mis 7 the possibility that this so far unique interglacial fossil assemblage is the result of acombination of local preservation potential and environmental factors however cannot be ruled out 2013 elsevier ltd and inqua

comparison of linear regression and a probabilistic neural network to predict porosity from 3 d seismic attributes in lower brushy canyon channeled sandstones southeast new mexico the lower brushy canyon formation of the delaware basin new mexico consists of a series of overlying sand filled channels and associated fans separated by laterally extensive organic siltstone and carbonate interbeds this laterally and vertically complex geology creates the need for precise interwell estimation of reservoir properties in this paper we integrate wireline log and 3 d seismic data to directly predict porosity in the area of an existing oil field in southeast new mexico the 3 d seismic data were used to interpret the location of major stratigraphic markers between wells and these seismic horizons were used to constrain a time window for a volume based attribute analysis stepwise regression and crossvalidation were used to combine seismic attributes to predict porosity in wells where the porosity was known from the well logs the results of a linear regression porosity model showed good correlation r2 0 74 between seven seismic attributes and the observed porosity logs at 11 wells in

gas hydrate physical properties imaging by multi attribute analysis blake ridge bsr case history abstract we analysed the bottom simulating reflector bsr of the blake ridge by using the multi attribute analysis this technique allows prediction of petrophysical geological parameters along seismic lines velocity porosity density resistivity etc starting from log data seismic attributes can be thought of as all parameters derived from seismics by assuming that a seismic trace is the real component of a complex one the first attributes that can be calculated are the instantaneous amplitude the instantaneous phase and the instantaneous frequency all the other attributes that will be considered are derived from the previous ones the algorithm that allows the correlation between logs and seismics is the generalised multiple linear regression this equation is solved by a least squares approach called training phase which effectively consists of training the seismics to predict the reservoir parameter of interest at the tie locations the resulting function is then applied to the seismic profile generating a target log predicted section we obtained five sections vsp and p wave velocity density porosity and resistivity each of them representing the distribution of the corresponding property along the profile they permitted better characterisation of the nature of the bsr present in the blake ridge area the obtained velocity section was finally translated in terms of gas hydrate and free gas distribution by using theoretical approach

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

estimation of biogenic silica contents in marine sediments using seismic and well log data sediment drift 7 antarctica petrophysical properties wet bulk density porosity p wave velocity are used to predict biogenic silica contents along a seismic reflection profile that ties two well sites 1095 and 1096 drilled by ocean drilling program odp leg 178 on sediment drifts on the pacific continental margin of the antarctic peninsula the biogenic silica contents along the seismic reflection profile were estimated on the basis of three hypotheses about petrophysical properties distributions in the two boreholes and statistical relationships between biogenic silica and other petrophysical properties which were established on various sediment layers within the boreholes our study demonstrates the possibility to reliably predict the distribution of biogenic silica in the sub seabed sediments if seismic data processed with amplitude preservation are used and statistical relations are considered we conclude that the statistical extrapolation of biogenic silica content along seismic reflection profiles tied to borehole data is an efficient tool to quantify the amounts of silica undergoing crystalline transformation which may have strong implications for submarine slope destabilisation

pleistocene deposits at stoke goldington in the valley of the great ouse uk at stoke goldington in the valley of the great ouse in buckinghamshire a river terrace at a height of about 7 m above the floodplain is underlain by fluvial sediments representing climatic fluctuations in the late middle pleistocene near the base of the succession at a level only 1 m above the modern floodplain a fossil assemblage including pollen plant macrofossils molluscs insects and ostracods provides evidence for the local development of herb rich grassland under temperate climatic conditions the fossil record amino acid racemisation ratios and uranium disequilibrium dating all suggest deposition of this material during oxygen isotope stage 7 the deposits containing the temperate assemblage are immediately overlain by typical cold climate gravels of the great ouse these have been subjected to a later cut and fill episode with the fill accumulating in cool climatic conditions the cut and fill episode was succeeded by aggradation forming the overlying terrace surface amino acid racemisation ratios indicate that the fill was emplaced and the terrace surface created during or after oxygen isotope stage 5 1996 john wiley sons ltd

pleistocene fluvial sediments palaeontology and archaeology of the upper river thames at latton wiltshire england pleistocene fluvial sediments of the northmoor member of the upper thames formation exposed at latton wiltshire record episodic deposition close to the churn thames confluence possibly spanning the interval from marine isotope stages mis 7 to 2 the sequence is dominated by gravel facies indicating deposition by a high energy gravel bed river a number of fine grained organic sediment bodies within the sequence have yielded palaeoenvironmental and biostratigraphical data from mollusca coleoptera vertebrates pollen and plant macrofossils the basal deposit facies association a contains faunal material indicating temperate conditions most of the palaeontological evidence including a distinctive small form of mammoth mammuthus cf trogontherii together with the u series age estimate of 147 4 20 kyr suggest correlation with mis 7 the overlying deposits facies associations b and c represent deposition under a range of climatic conditions two fine grained organic deposits occurred within association b one association ba in the northern part of the pit as a channel fill and the other association bb in its southern part as a scour fill deposit the coleopteran assemblages from ba indicate that it accumulated under temperate oceanic conditions while bb which also yielded a radiocarbon age estimate of 39 560 780 14c yr bp was formed under much colder and more continental climatic conditions the sequence is considered to represent deposition within an alluvial fan formed at the churn thames confluence a depositional scenario which may account for the juxtaposition of sediments and fossils of widely differing age within the same altitudinal range

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

late and middle pleistocene deposits at somersham cambridgeshire u k a model for reconstructing fluvial estuarine depositional environments gravel quarries at somersham cambridgeshire have yielded evidence for a pleistocene channel of the r great ouse containing temperate stage sediments between cold stage sediments in the earlier cold stage fluviatile gravels and floodplain loessic sediment accumulated in the later cold stage a further series of gravel units and floodplain sediments were deposited together with lake sediments the lake sediments are associated with lake sparks dammed by late devensian ice in the wash at ca 18 5 ka bp the lake sediments overlie gravels with a radiocarbon date from an organic horizon indicating a middle devensian age clast lithological analyses from the earlier and later gravels suggest that reworking of gravels has occurred within a relatively stable catchment the petrography of the earlier cold stage loessic sediment and temperate stage fine sediment indicates an anglian affinity which conflicts with the biostratigraphic interpretation pollen and macroscopic plant remains from sediments of both cold stages and from the temperate stage indicate respectively assemblages with a typical full glacial aspect with a rich flora of shrubs and open ground herbs including an assemblage at ca 18 ka and temperate freshwater and marine influenced organic sediments on the basis of pollen analysis these are ascribed to substages ip ii and iii of the ipswichian stage o i s 5e with a pinus quercus corylus biozone in the former and a biozone with carpinus in the latter marine influenced sediments at 3 7 to 0 3 m od indicate transgression in ip ii and regression in ip iii molluscan assemblages from the temperate stage and the later cold stage are described two are from the late devensian at a time near the maximum extension of ice into the wash foraminifer and ostracod faunas are described from post ipswichian sediments and may be reworked radiocarbon dates confirm the age of the later gravel suite as devensian and a calibration of the measurements is given amino acid ratios from corbicula fluminalis valves from temperate stage sediments are reported with measurements from different parts of the valve the results tend to support an ipswichian age tl measurements of the earlier cold stage loessic sediment and associated sand indicate a pre ipswichian age for the sediments the earlier cold stage is correlated with the pre ipswichian cold stage the wolstonian of mitchell et al 1973 problems with this correlation are discussed various periglacial phenomena including thermal contraction networks and cracks diapirs involutions and coversand are associated with the devensian sequence the complex environmental history based on stratigraphy and palaeontology is described and related to other nearby sites in southern fenland