stratigraphy structure absolute age and paleontology of the upper pleistocene deposits at sankaty head nantucket island massachusetts the sankaty head cliff of nantucket island massachusetts exposes drift of at least two glaciations and interglacial marine deposits radiocarbon amino acid racemization and uranium thorium analyses were used to determine the absolute ages of the beds the results indicate that 1 the sankaty sand correlates with oxygen isotope stage 5 sangamonian 2 the underlying drift is older than stage 5 illinoian or older and 3 the overlying drift is wisconsinan in age ostracodes and molluscs within the sankaty sand indicate that the marine climate during deposition of the lower part was somewhat warmer than the present climate off sankaty head and that the marine climate during the deposition of the upper part was as cold as or somewhat colder than the present climate the paleoenvironmental data support a stage 5 sangamonian age for the marine deposits

amino acid epimerization implies rapid sedimentation rates in arctic ocean cores the palaeooceanography of the arctic ocean is less well known than any other ocean basin due to difficulties in obtaining cores and in providing a secure chronological framework for those cores that have been raised most recent investigators have suggested that low sedimentation rates 0 05 0 1 cm kyr 1 have characterized the deep basins over the past 5 myr refs 1 2 despite the glacial marine character of the sediment and proximity to major centres of shelf glaciation these calculations have been primarily based on the down core pattern in the inclination of magnetic minerals supported by uranium series 14c and micropalaeontological evidence here we analyse amino acid diagnesis in foraminifera from two gravity cores raised from the floor of the arctic ocean our results suggest that these cores span 200 kyr conflicting with the earlier estimate of 3 myr based on palaeomagnetic data the chronology of other arctic ocean cores and previous palaeoenvironmental interpretations need re evaluation

u series and amino acid dates from jersey understanding of the raised beach and other interglacial sequences in the southern part of the british isles has been improved through use of the amino acid racemization technique this method has permitted correlation of these isolated and fragmentary marine deposits1 2 which except for the portland site are located around the shores of the bristol channel1 by applying this technique with the u series method we have obtained a geochronometric date from the 8 m raised beach of the belle hougue cave jersey channel islands our results suggest that the 8 m raised beach of the channel should be correlated with isotope stage 5 and that raised beaches above this altitude in the area may pre date this stage and thus also the ipswichian interglacial which forms part of it

esr dating in quaternary geology abstract electron spin resonance esr a relatively new dating technique was first suggested by zeller et al 1967 zeller 1968 and levy 1968 it has made substantial progress in frequent applications in the last few years esr dating is based on the direct measurement of the amount of radiation induced paramagnetic electrons trapped in crystal defects these free electrons were generated by alpha beta and gamma radiation of natural radioelements e g u th k and have accumulated in the minerals over geologic time the esr age is obtained by dividing the total amount of accumulated radiation dose archaeological dose ad by the dose per year annual dose this review comprises four major parts the principles of the method the determination of the archaeological dose ad the determination of the annual dose and a compilation of datable materials several questions remain the evaluation of the ad the determination of the annual dose and particularly with respect to the nature and stability of the electron traps used for dating

relative sea level fall since the last interglacial stage are coasts uplifting worldwide the growing interest in quantification of vertical ground motion stems from the need to understand in detail how the earth s crust behaves for both scientific and social reasons however only recently has the refinement of dating techniques made possible the use of paleoshorelines as reliable tools for tectonic studies although there are many local studies of quaternary vertical motions of coastlines we know of no comprehensive worldwide synthesis here we provide a compilation of 890 records of paleoshoreline sequences with particular emphasis on the last interglacial stage marine isotopic stage mis 5e 122 ka the quality of dating mis 5e makes it a reliable marker to evaluate vertical ground motion rates during the late quaternary on a global scale the results show that most coastal segments have risen relative to sea level with a mean uplift rate higher than 0 2 mm yr i e more than four times faster than the estimated eustatic drop in sea level the results also reveal that the uplift rate is faster on average for active margins than for passive margins neither dynamic topography nor glacio hydro isostasy may explain sustained uplift of all continental margins as revealed by the wide distribution of uplifted sequences of paleoshorelines instead we suggest that only plate tectonic processes reconcile all observations of quaternary coastal uplift we propose that long term continental accretion has led to compression of continental plates and uplift of their margins therefore this study concludes that plate tectonics processes impact all margins and emphasizes the fact that the notion of a stable platform is unrealistic these results therefore seriously challenge the evaluation of past sea levels from the fossil shoreline record

correlation and dating of quaternary littoral zones along the patagonian coast argentina six areas of the patagonian coast argentina were investigated in order to determine the number characteristics geomorphology and development of quaternary littoral zones it became apparent that utilizing dl ratios of aspartic acid and leucine of various molluscan species would be the most useful in correlation relative age dating and estimating the ages of these zones the oldest littoral zone is found at elevations between 24 and 41 m above mean sea level and is judged to be older than oxygen isotope substage 5e in age based on relatively high amino acid ratios and extrapolated from non linear kinetic models an intermediate aged littoral zone may be present at some locations based upon beach ridges or platforms varying in elevation between 16 and 28 m above mean sea level dl ratios are generally lower than those for the oldest zone but show a greater variation this zone may represent the substage 5e sea level stand well defined young beach ridges 8 12 m above mean sea level are found in most locations and have been 14c dated and verified by amino acid ratios as being holocene the presence of quaternary aged emerged littoral zones at roughly the same elevation suggest that the glacio eustatic contribution is the primary cause of the high sea level stands whereas secondary variations are attributed to other factors

a review of amino acid racemization studies in quaternary mollusks stratigraphic and chronologic applications in coastal and interglacial sites pacific and atlantic coasts united states united kingdom baffin island and tropical islands abstract amino acid racemization aar studies of quaternary mollusks mostly marine mollusks from coastal deposits are reviewed data obtained in regional studies from the u s atlantic and pacific coasts baffin island the united kingdom and tropical islands are discussed as they relate to method evaluation kinetic model development and aminostratigraphic applications u s pacific coast studies have been employed for estimating tectonic deformation rates study of molluscan zonation patterns in the late pleistocene and in kinetic model evaluation u s atlantic coast studies have identified multiple aminostratigraphic zones in areas with complex morphostratigraphic relationships and have also revealed some important conflicts between aminostratigraphic temperature concepts and radiometric data studies in the united kingdom involving coastal sites and non marine interglacial sites identify some stratigraphic and kinetic conflicts but provide a preliminary chronostratigraphic model for the classical interglacial terminology of the u k middle to late pleistocene baffin island studies involving aar data and u th dating of shells have resulted in some significant revisions of previous chronologic models the arctic environment has also stimulated some novel approaches in the collection and interpretation of aar results tropical island studies though few in number aid in calibration of observed racemization and also aid in correlation of coastal deposits with late pleistocene isotopic ice volume records

stratigraphy of late quaternary estuarine deposits and amino acid stereochemistry of oyster shells beneath san francisco bay california abstract the sequence of quaternary deposits beneath the floor of san francisco bay includes four to seven noncontemporaneous estuarine units intercalated with alluvium and dune sand units l 0 10 000 b p m 40 000 b p probably ca 80 000 140 000 b p and n older than unit m are distinctly superposed the dominant molluscan fossil in each of these three units is ostrea lurida carpenter the native oyster along much of the pacific coast of north america despite a lamellar structure that suggests vulnerability to contamination o lurida shells generally yield amino acid enantiomeric ratios that are analytically reproducible and stratigraphically consistent the kinetics of racemization in o lurida conceivably resembles that of protothaca and saxidomus other bivalves whose kinetics of racemization are relatively well understood assuming such a resemblance enantiomeric ratios in o lurida imply that 1 unit m is the same approximate age as estuarine terrace deposits bordering san pablo bay and carquinez strait providing that the terrace deposits have been at diagenetic temperatures 1 2 c warmer than unit m and 2 the age of unit n is about four times greater than that of unit m providing that both units have been at the same approximate diagenetic temperature

reconstructing estuarine conditions oyster shells as recorders of environmental change southwest florida abstract live collected shells of the oyster crassostrea virginica contain geochemical records of modern temperature and salinity so records of prehistoric conditions may be obtained from subfossil shells restoration of channelized watersheds in florida is receiving much attention and plans for targeted watersheds require information about estuarine conditions before channelization lack of historical records necessitates alternative methods to understand pre disturbance conditions a 14c calibrated amino acid geochronology based on racemization of glutamic acid yielded ages ranging from 190 1220 ad and from 1270 1860 ad for subfossil oysters from blackwater river near natural watershed and for faka union bay channelized watershed respectively 18o and 13c values of subfossil shells from blackwater river indicate salinity and summer temperatures similar to present winter temperatures recorded in shells from 190 590 720 and 1050 ad appear 1 5 c colder than present winter temperatures whereas the shell from 1220 ad records winter temperatures similar to modern winter temperatures these temperature shifts may indicate change in climate or natural seasonal variation of winter temperature from year to year subfossils from faka union bay may reflect a complicated hydrology which cannot be evaluated by isotopic compositions alone and demonstrates the need for development of independent elemental proxies for temperature and salinity decreases in 13c from subfossil to modern shells may in part result from co2 added to the atmosphere from fossil fuel burning the suess effect subfossil 13c that is 1 more positive than modern shells suggest a change in the dominant carbon sources from terrestrial c4 or aquatic plants to c3 plants mangroves

palynological foraminiferal and aminostratigraphic studies of quaternary sediments from the u s middle atlantic upper continental slope continental shelf and coastal plain abstract a pollen climate index curve provides the basic stratigraphic subdivision of the 305 m cored quaternary section of amcor 6021c located on the upper continental slope off new jersey u s a cold and warm intervals from top to bottom were assigned to marine oxygen isotope stages 1 through 13 at a sub bottom depth of about 220 m foraminiferal data indicate a possible hiatus and if so sediments below this may be as old as isotope stage 16 or older aminostratigraphic studies yielded results that are consistent with either interpretation benthic foraminifers are dominated by elphidium excavatum and islandiella norcrossi the planktic foraminiferal record provided no independent means of subdividing the section the stratigraphic distribution in 6021c of six species of quercus oak and aminozone determinations were applied to dating in terms of presumed oxygen isotope stages of other offshore core hole samples and some onshore quaternary deposits of delaware stratigraphic information from amcor sites 6021 and 6009 correlated to seismic reflection profiles that cross the shelf slope break indicate that the thickest accumulations of terrigenous quaternary sediments are located along the outer continental shelf upper continental slope offshore the northeastern united states

evidence for a middle pleistocene glaciation of mis 8 age in the southern north sea abstract in the cores of borehole 89 2 situated at 54 00 01 n and 5 00 04 e about 70 km north of the frisian islands in the southern north sea two diamictons levels are found at 70 and 100 m below sea floor i e 110 and 140 below present sea level respectively both diamictons appear to be older than saalian mis 6 in contrast to earlier interpretations the upper diamicton is overlain by about 20 m of shallow marine sands followed by a chaotic alternation of fine grained clay rich eemian mis 5e sediments and sands deposited in a glacially excavated basin it was originally assumed that this diamicton was saalian mis 6 in age and lined the base of the basin seismic lines crossing the borehole location however show that the upper diamicton is truncated by the basin and consequently must be older than saalian this is corroborated by new investigations on the saalian eemian transition in the netherlands and new data on the age of the molluscs and foraminifera in the sands directly overlying the upper diamicton the age data based on measurements of the isoleucine epimerisation of mollusc shells and foraminiferal tests favour an mis 8 age

coastal tectonics on the eastern margin of the pacific rim late quaternary sea level history and uplift rates channel islands national park california usa abstract the pacific rim is a region where tectonic processes play a significant role in coastal landscape evolution coastal california on the eastern margin of the pacific rim is very active tectonically and geomorphic expressions of this include uplifted marine terraces there have been however conflicting estimates of the rate of late quaternary uplift of marine terraces in coastal california particularly for the northern channel islands in the present study the terraces on san miguel island and santa rosa island were mapped and new age estimates were generated using uranium series dating of fossil corals and amino acid geochronology of fossil mollusks results indicate that the 2nd terrace on both islands is 120 ka and the 1st terrace on santa rosa island is 80 ka these ages correspond to two global high sea stands of the last interglacial complex marine isotope stages mis 5 5 and 5 1 respectively the age estimates indicate that san miguel island and santa rosa island have been tectonically uplifted at rates of 0 12 0 20 m ka in the late quaternary similar to uplift rates inferred from previous studies on neighboring santa cruz island the newly estimated uplift rates for the northern channel islands are however an order of magnitude lower than a recent study that generated uplift rates from an offshore terrace dating to the last glacial period the differences between the estimated uplift rates in the present study and the offshore study are explained by the magnitude of glacial isostatic adjustment gia effects that were not known at the time of the earlier study set in the larger context of northeastern pacific rim tectonics channel islands uplift rates are higher than those coastal localities on the margin of the east pacific rise spreading center but slightly lower than those of most localities adjacent to the cascadia subduction zone the uplift rates reported here for the northern channel islands are similar to those reported for most other localities where strike slip tectonics are dominant but lower than localities where restraining bends such as the big bend of the san andreas fault result in crustal shortening

isoleucine epimerization in quaternary benthonic foraminifera from the norwegian continental shelf a pilot study abstract the extent of epimerization of the protein amino acid l isoleucine has been measured in late quaternary benthonic foraminifera found in cores from two areas of the norwegian continental shelf in order to evaluate the potential of this reaction as a geochronological tool measurements were restricted to monospecific assemblages of cibicides lobatulus and elphidium excavatum from 14 c dated and seismostratigraphic units representing a range of ages by comparing with data on the same species from last interglacial and late glacial sites in western norway miller et al 1983 and with the assumption of similar temperature history for the shelf and coastal areas the absolute ages of the samples are discussed of the nine samples analysed one was of holocene seven of late to middle weichselian and one sample of pre weichselian age from this pilot study we conclude that isoleucine epimerization ratios in benthonic foraminifera provide a reliable index of relative age that can be used to correlate sedimentary units that contain in situ faunas and have similar thermal histories absolute ages of the enclosing sediment can be approximated if suitable well studied calibration sites are available

historical developments and recent advances in amino acid geochronology applied to loess research examples from north america europe and china abstract amino acid geochronology provides important chronostratigraphic insight in the regional correlation and paleoclimatic evaluation of loess paleosol sequences in the midwestern us throughout western central and eastern europe and in china in general loess of the last four glacial cycles corresponding to marine oxygen isotope stages ois 2 4 6 8 and 10 respectively can be distinguished on the basis of alloisoleucine isoleucine a i ratios measured in fossil gastropod shells preserved in the loess the racemization reaction is much slower in older samples resulting in decreased temporal resolution in the midwestern us and europe it is not possible to confidently subdivide the last glacial cycle on the basis of aminostratigraphic data however in china where effective temperatures were higher during the late pleistocene loess above and below l1ss1 the ois 3 interstadial paleosol can be distinguished using amino acid racemization data with improvements in analytical methods multiple amino acid d l enantiomers are now being measured using reverse phase liquid chromatography aspartic acid racemizes at a higher rate than the traditionally measured alloisoleucine isoleucine diastereomers and can be measured more rapidly this development offers hope for better temporal resolution and enhanced stratigraphic subdivision of loess units than has been achieved previously

amino acid geochronology of raised beaches in south west britain abstract based on 1 the epimerization of l isoleucine to d alloisoleucine d l ratios in patella vulgata littorina littorea l littoralis l saxatilis littorina species and nucella lapillus from raised beaches in south west britain 2 statistical analysis of the d l ratios and 3 lithostratigraphic and geomorphic evaluation three d l stages are proposed the d l ratios for all the species measured are converted to a patella vulgata standard the three d l stages are 1 1 the minchin hole d l stage d l ratios 0 175 0 014 defined at a stratotype in minchin hole cave gower wales 2 2 a provisionally defined but as yet unamed d l stage because of the current unavailability of a suitable stratotype with d l ratios of 0 135 0 014 3 3 the pennard d l stage d l ratios 0 105 0 016 defined at a stratotype in minchin hole cave gower wales two geochronological models of the three high sea level events representing the d l stages are constrained by uranium series age determinations on stalagmite interbedded with marine beds in minchin hole and bacon hole caves gower wales a potential fixed point in model evaluation is an age determination which is equivalent to oxygen isotope sub stage 5e 122 ka the two models are oxygen isotope stage and age ka bp d l stage d l ratio model 1a model 1b model 2 pennard 0 105 0 016 5a ca 80 5e 122 5e 122 5c ca 100 unnamed 0 135 0 014 5e 122 7 194 minchin hole 0 175 0 014 7 186 245 7 186 245 7 216 the ages of the raised beaches are used to constrain the timing and extent of glaciation in the area the extent of the late devensian glaciation is fixed by reference to localities where raised beaches of the pennard d l stage outcrop as well as by using unpublished data on molluscs incorporated into glacial deposits two pre devensian glaciations antedate the minchin hole d l stage the irish sea glaciation of the bristol channel irish sea older drift of south wales fremington till of north devon is ascribed to oxygen isotope 10 or earlier while the paviland welsh glaciation is ascribed to oxygen isotope stage 8 or earlier an earlier glaciation berwyn glaciation is inferred from erratics of known welsh provenance in essex

a petrological and geochemical study of the calcareous sandstone of west african marine pleistocene cap des biches senegal abstract in senegal the marine pleistocene is represented by several outcrops of calcareous sandstone slabs which underly the recent sandy shoreline south of dakar these outcrops show dissolution and recrystallization phenomena increasingly evident as one moves south they disappear at toubab dialao i e approximately 40 km from dakar the outcrop at cap des biches has been studied mainly because of the exceptional preservation of some ostrea calcitic tests which allowed isotopic u th measurements this outcrop of metric thickness was subjected to petrographic and mineralogical examination and to several geochemical analyses trace elements stable isotopes amino acids which lead to the conclusion that the base of the deposit has been preserved two u th apparent ages obtained 178 ka and 240 ka are older than the only age of the isotopic stage 5c obtained in the area a post depositional mobility of u cannot be rejected and ages may not be reliable however a minimal age considerably older than finite 14c ages previously published may be proposed eemian interglacial i e isotopic stage 5 in these environments geochemical analyses show high pleistocene sea levels of either warmer and or more diluted waters than the present levels i e a probable northern extension of guinean waters

prograding coastal facies associations in the vryheid formation permian at effingham quarries near durban south africa abstract this paper describes and interprets a flat lying sandstone siltstone sequence 70 m thick in three disused quarries the beds comprise the lowest part of the vryheid formation middle ecca in the durban vicinity the sequence is conveniently divisible into two parts the lower division constitutes a prograding beach barrier association while the upper one represents a back barrier lagoonal complex fourteen sedimentary facies are described and interpreted to represent a range of depositional environments including open water shelf silts sandy shoreface and littoral deposits organic rich muds and peats of lagoonal origin a tidal inlet washover fans and a fluvial channel sand among the conclusions reached are that the local middle ecca coastline extended in a northwest to southeast direction and that progradation was towards the southwest that the coastline was microtidal and that stormy conditions were common with prevalent palaeowinds from the northwest the absence of invertebrate body fossils in these strata is attributed to penecontemporaneous solution of shelly remains this is the first time that a coastal sequence has been identified on the southeast margin of the main karoo basin of south africa

aminostratigraphic relations and age of quaternary deposits northern espanola basin new mexico abstract amino acid ratios of gastropods provide a useful basis for correlation and approximate dating of middle to late quaternary fluvial deposits from the northern espanola basin new mexico sparsely fossiliferous slackwater deposits in the rio chama rio grande floodplain were buried episodically by piedmont alluvium during periods of climatic change as the axial river system cut down 120 m during the past 620 000 yr alloisoleucine isoleucine alle ile ratios in the total hydrolysate and free fraction of amino acids in succinea and vallonia are strongly correlated with elevation ratios in succinea range from 0 01 to 0 79 in the total hydrolysate and from 0 00 to 1 15 in the free fraction for deposits that range in age from modern to 620 000 yr old amino acid ratios are tightly clustered for deposits that contain the 620 000 yr old lava creek b tephra layer demonstrating their utility for correlation and providing a calibration point for a local dating curve two 14c ages from younger deposits and limiting ages for erosion surfaces that lie above gastropod bearing units tend to support the validity of much of the curve combining the dating curve with the geologic constraints suggests that aggradation events separated by episodes of net incision occurred at about 620 000 310 000 70 000 170 000 40 000 95 000 15 000 yr ago after 19 000 yr ago and during two minor periods between 80 000 and 25 000 yr ago

an evaluation of uranium series dating of fossil echinoids from southern california pleistocene marine terraces abstract fossil sea urchins strongylocentrotus from pleistocene marine terraces on the southern california channel islands have been dated by the uranium series method in order to test the suitability of echinoids for dating marine terraces results indicate that urchin plates and spines do not behave as closed systems with respect to both uranium and thorium calculated ages based on these data do not agree with uranium series ages 120 000 and 127 000 yrs obtained previously from corals from the same localities thus fossil sea urchins strongylocentrotus are not considered suitable for uraniumseries dating of pleistocene marine terrace deposits

rapid racemization of aspartic acid in mollusc shells and potential for dating over recent centuries dating of deposits and materials less than 350 years old is hindered by the very poor time resolution of the radiocarbon method over this period1 2 fluctuations in atmospheric 14c levels result in the existence of several possible calendric ages for any given radiocarbon age for terrestrial samples in the marine record these fluctuations are dampened however only a small change in marine radiocarbon ages occurs over this period from ad 1700 to 1950 radiocarbon ages become only 100 yr younger2 consequently age resolution is poor furthermore there is an uncertainty in the amount of the correction for the reservoir effect the apparent radiocarbon age of modern marine carbon typically 400yr which reflects the average residence time of carbon in the oceans amino acid racemization epimerization analysis has been used primarily for dating samples older than the limit of radiocarbon dating 40 000 50 000 yr bp 3 4 here i show that aspartic acid asp in mollusc shells has racemized particularly rapidly over the past few centuries analyses done on land snails from deposits in the negev desert eolianites in madeira cave deposits in jamaica and from museum collections indicate racemization rates of 2 5 per century asp racemization thus provides a means of dating recent faunal assemblages of molluscs and other biogenic carbonates as well as recent terrestrial fluvial and marine sedimentary sequences that contain molluscs

age estimates and uplift rates for late pleistocene marine terraces southern oregon portion of the cascadia forearc marine terraces are prominent landforms along the southern oregon coast which forms part of the forearc region of the cascadia subduction zone interest in the cascadia subduction zone has increased because recent investigations have suggested that slip along plates at certain types of convergent margins is characteristically accompanied by large earthquakes in addition other investigations have suggested that convergent margins can be broadly classified by the magnitude of their uplift rates with these hypotheses in mind we generated new uranium series amino acid and stable isotope data for southern oregon marine terrace fossils these data along with terrace elevations and two alternative estimates of sea level at the time of terrace formation allow us to determine terrace ages and uplift rates uranium series analysis of fossil coral yields an age of 83 5 ka for the whisky run terrace at coquille point in bandon oregon a combination of amino acid and oxygen isotope data suggest ages of about 80 and 105 ka for the lowest two terraces at cape blanco these ages indicate uplift rates of 0 45 1 05 and 0 81 1 49 m kyr for coquille point and cape blanco respectively late quaternary uplift rates of marine terraces yield information about deformation in the overriding plate but it is unclear if such data vary systematically with convergent margin type in order to assess the utility of the southern oregon uplift rates for predicting the behavior of the cascadia subduction zone we compared late quaternary uplift rates derived from terrace data from subduction zones around the world on the basis of this comparison the southern oregon rates of vertical deformation are not unusually high or low furthermore late quaternary uplift rates show little relationship to the type of convergent margin these observations suggest that local structures may play a large role in uplift rate variability in addition while the type of convergent margin may place an upper limit on possible uplift rate greater upper limits serve to increase the range of possible uplift rates in the case of the southern oregon coast variability in uplift rate probably reflects local structures in the overriding plate and the rate of uplift cannot be used as a simple index of the potential for great earthquakes along the southern cascadia subduction zone

amino acid geochronology its impact on our understanding of the quaternary stratigraphy of the british isles this review aims to act as a brief primer to amino acid racemization and protein breakdown as well as to document the major applications and results of amino acid dating on british quaternary sediments amino acid results from fossil shells have had far reaching effects in developing our current understanding of british quaternary stratigraphy and its links to continental europe and the marine record to appreciate the potential for amino acid geochronology the technique s limitations and recent developments are discussed as well as the future of the field copyright 2009 john wiley sons ltd

quaternary stratigraphy of the fladen area central north sea a multidisciplinary study based on detailed stratigraphic investigations on a 200 6m long core bgs borehole no 81 26 from the fladen ground area british sector core material from the sleipner field norwegian sector and shallow seismic profiles between the core sites the following conclusions are drawn 1 the north sea was glaciated sometime during th elaterpart of matuyama reversed period a complete glacial interglacial glacial cycle is recorded in these sediments 2 in a period of marine sedimentation in the middle pleistocene a transgression regression cycle under boreal arctic regime is recorded 3 the fladen area has subsided between 0 9 and 0 6 m ka through the later parts of the quaternary 4 a major glacial event dated at between 130 and 200 ka is recorded as a thick till unit in 81 26 this till which was deposited by ice moving from the southwest scotland probably represents a period when the scandinavian and british ice sheets coalesced in the north sea 5 based on the seismic data and the stratigraphy of the sleipner core an ice free open embayment dry land is favoured for the central north sea during the late weichselian 6 from the amino acid data it is shown that there has been an episodic style of sedimentation through the quaternary 7 of the investigated sediments which span the last 1 mill year ca 98 have been deposited under arctic to boreal arctic conditions

precambrian cambrian boundary recent state of knowledge abstract the principle of biostratigraphic delimitation of the type lower boundary of the cambrian system has become generally accepted despite a lack of recent results which further support this approach the detection of the most ancient vendian ediacara softbodied forms and cambrian skeletal fauna in a large number of localities worldwide has been the only obvious trend in recent investigations the present agreement that the base of the tommotion stage is the most satisfactory position for the precambrian cambrian boundary is based on the idea that the best type section of the boundary is to be found in the siberian platform such a decision is based largely on the unsatisfactory nature of the arguments for alternative positions

time stratigraphic aspects of a formation interpretation of surficial pleistocene deposits by analogy with holocene paralic deposits southeastern delaware pleistocene shoreline deposits in close spatial and temporal proximity to holocene deposits permit detailed interpretation of the development of pleistocene coastal deposits when a modern ancient analog approach is used peak sea levels during the past 1 m y or more have allowed the preservation of transgressive shoreline systems here referred to as paralic units along the inner continental margin these pleistocene paralic units are similar to holocene coastal deposits now forming on delmarva peninsula the omar formation early to late pleistocene age incorporates at least four juxtaposed transgressive paralic units of different ages each containing deposits of lagoonal sands and muds tidal marsh barrier sands and gravels tidal delta sands and silty sands and tidal channel sands and gravels the successive paralic units become younger in the seaward direction thus although the omar formation in the study area is almost entirely made up of transgressive deposits produced during rising sea levels in a longer time frame it forms a progradational sequence only about 2 to 5 of the elapsed time during the deposition of the studied part of the omar formation is represented by sedimentary units the internal time stratigraphy of the omar formation is extremely complex this makes the time stratigraphic interpretation of any one outcrop or drill hole difficult any lithologic change may represent a wide variety of time gaps from minutes to tens of thousands of years the analog approach in which sedimentary lithosome mapping is used allows one to infer a time stratigraphic framework of the deposits these concepts can aid in the interpretation of depositional history of older paralic deposits and the nature of the development of certain types of clastic formations

comparison of uranium series radiocarbon and amino acid data from marine molluscs baffin island arctic canada uranium series and sup 14 c dates and the extent of amino acid racemization are reported for 24 marine shell samples from three areas of baffin island arctic canada when the radiometric dates are plotted against the ratio of d alloisoleucene l isoleucene in the shells five broad age groups are recognized the uranium series data indicate that sup 231 pa is incompletely retained in most fossil shells and that sup 230 th is lost from some of the samples therefore their apparent ages are minimum however a few dated samples in each group have yielded useful age results and the minimum ages of the five groups of samples are estimated as 7 000 to 11 000 greater than or equal to70 000 greater than or equal to136 000 greater than or equal to190 000 and 300 000 yr calculated integrated thermal histories based on the epimerization reaction in the mollusc hiatella arctica linne give paleotemperature estimates of around 5 sup o c compared to the present mean annual air temperature of about 11 sup o c

quaternary glacial and marine stratigraphy of the qivitu peninsula northern cumberland peninsula baffin island canada summary sediments exposed along the outer coast of the qivitu peninsula record the advances and retreats of glaciers in the fiords bordering the peninsula and accompanying sea level fluctuations during the quaternary seven main lithofacies and 21 subfacies are recognized based on texture color bed thickness and lateral extent internal structures and abundance of macrofossils in contrast to earlier work in the area the interpretation of lithofacies genesis using a model of fiord glaciomarine sedimentation suggests that all lithofacies are of marine or glaciomarine origin with no evidence of grounded ice extending seaward of the peninsula the abundance and diversity of benthic foraminifera in selected samples and in situ subarctic molluscs shows that relatively warm water was present along the east baffin island coast during several periods of extensive fiord glaciers analysis of upward facies transitions in 54 stratigraphic sections suggests that facies sequences are cyclical these sedimentation cycles are interpreted in terms of glacier sea level responses during glacial interglacial cycles detailed relative time control for the lithofacies sequence is provided by time dependent amino acid ratios on the common shell fragments in many stratigraphic units because the stratigraphic sequence is marked by significant unconformities due to relative sea level regressions near the end of each glacial sedimentation cycle amino acid ratios on molluscs contemporaneous with particular cycles are statistically similar and distinct from ratios for older and younger cycles thus although few stratigraphic units can be physically traced for more than 0 5 km aminozones based on groups of animo acid ratios allow chronocorrelation and relative dating of units in each sedimentation cycle the qivitu stratigraphic sequence is divided into two formations consisting of a total of seven members for which formal names are proposed sediments predating the two most recent interglacials are lithologically similar to later beds suggesting that events during these earlier periods were of the same character as those of later glacial interglacial cycles biostratigraphic evidence suggests that a relatively mild climate prevailed in this region during the clyde and ayr lake glaciations and intervening cape broughton aquatherm the quajon interstade is correlative with the marine sediments deposited near the end of the ayr lake glaciation rather than the cape broughton aquatherm soil horizons indicate regressions at the end of the cape broughton aquatherm and ayr lake glaciation and pollen assemblages suggest that the terrestrial climate may have been warmer than the present climate a reinterpretation of u series dates and amino acid ratios on shells suggests that the cape broughton aquatherm and earlier events predate marine oxygen isotope substage 5e the ayr lake glaciation may have occurred well before the major interglacial glacial transition in more temperate latitudes but evidence from ocean cores in the north atlantic and ice cores from greenland and devon island supports the interpretation of warm water incursions into baffin bay during this ice advance following substage 5e by inference relative sea level during the period following the ary lake glaciation was lower than present sea level and glacier extent was restricted no evidence of an exceptionally cold dry climate has been found however distal glaciomarine sediments in the upper coastal cliffs suggest a limited readvance of fiord glaciers prior to the holocene near the beginning of the holocene 10 000 yr b p warmer water extended into the area as relative sea level fell and subsequently rose again to 15 m about 8 200 yr b p pollen assemblages in peat horizons suggest that during the earliest holocene a climate milder than that of the present day existed local deposition of eolian and soliflucted sediment may indicat deteriorating climate in late holocene time

bermuda sea level during the last interglacial bermuda is a stable mid oceanic carbonate platform for which a particularly complete record of sea level fluctuation during the period 135 70 kyr has been reconstructed from 230th 234u dating of corals and speleothems amino acid racemization dating of molluscs and a reinterpretation of geological field relations during the past 5 yr bermuda has been the focus of an extensive geochronological programme which has included a detailed re examination of the geology to be reported elsewhere1 3 here we focus only on the latest interglacial sequence we use the stratigraphie nomenclature of land et al 4 but will present new age data and interpretations of geological relationships this information as it relates to the last interglacial period is given in tables 1 and 2 and summarized in fig 1 we show that during the last interglacial period sea level was only above its present level for a few thousand years at about 125 kyr when it stood at 4 to 6m at 105 and 85 kyr sea level rose to between 15 and 20 m as constrained by ages for submerged speleothems and eolianites at 95 kyr sea level in bermuda was at least 15 m below present level

paleotemperatures and the glacially induced changes in the oxygen isotope composition of sea water during late pleistocene and holocene time in tanner basin california oxygen isotope analyses of the benthic foraminiferal species uvigerina peregrina show that glacially induced changes in the isotopic composition of sea water reached a maximum of 1 5 in late pleistocene time in tanner basin southern california isotopic data derived from the planktonic species globigerina quinqueloba corrected for glacial and regional water mass effects indicates that an increase in mean surface water temperatures of about 5 c took place from near the end of the wisconsin glaciation to the holocene thermal maximum at about 7 500 yr b p the isotopic minimum recorded by u peregrina at about 40 000 yr b p is unusually low compared to that found in open ocean cores

theoretical correlations and lateral discontinuities in the quaternary aminostratigraphic record of the u s atlantic coastal plain abstract aminostratigraphic correlations of emergent quaternary deposits along the u s atlantic coastal plain have employed independent radiometric data regional temperature history models and assumptions regarding the nature of the preserved late quaternary sea level record on this passive margin a substantial aminostratigraphic offset is required if regional aminozones are rigorously constrained by all available th u data new insights regarding the relation of this offset to subsurface stratigraphy in the cape fear region of southeastern north carolina can explain these conflicts as consequences of the highly incomplete post cretaceous depositional record of the region southward projection of theoretical aminostratigraphic correlation trends suggests that stage 5 correlative marine units are rarely preserved on the emergent portion of the coastal plain between cape lookout and central south carolina and that samples of this age would be most frequently found in this region only as fragmentary and or reworked deposits on the inner shelf or in the subsurface of modern barrier islands if this hypothesis is correct then the accuracy of several th u coral dates from the south carolina coastal plain must be questioned along with sea level tectonic and paleoclimatic conclusions derived from these dates

quaternary sea level history and the origin of the northernmost coastal aeolianites in the americas channel islands national park california usa abstract along most of the pacific coast of north america sand dunes are dominantly silicate rich on the california channel islands however dunes are carbonate rich due to high productivity offshore and a lack of dilution by silicate minerals older sands on the channel islands contain enough carbonate to be cemented into aeolianite several generations of carbonate aeolianites are present on the california channel islands and represent the northernmost quaternary coastal aeolianites on the pacific coast of north america the oldest aeolianites on the islands may date to the early pleistocene and thus far have only been found on santa cruz island aeolianites with well developed soils are found on both san miguel island and santa rosa island and likely date to the middle pleistocene the youngest and best dated aeolianites are located on san miguel island and santa rosa island these sediments were deposited during the late pleistocene following the emergence of marine terraces that date to the last interglacial complex 120 000 yr to 80 000 yr based on radiocarbon and luminescence dating the ages of these units correspond in time with marine isotope stages mis 4 3 and 2 sea level was significantly lower than present during all three time periods reconstruction of insular paleogeography indicates that large areas to the north and northwest of the islands would have been exposed at these times providing a ready source of carbonate rich skeletal sands these findings differ from a previously held concept that carbonate aeolianites are dominantly an interglacial phenomenon forming during high stands of sea in contrast our results are consistent with the findings of other investigators of the past decade who have reported evidence of glacial age and interstadial age aeolianites on coastlines of australia and south africa they are also consistent with observations made by darwin regarding the origin of aeolianites on the island of st helena in the south atlantic ocean more than a century and a half ago

quaternary climates and sea levels of the u s atlantic coastal plain uranium series dating of corals from marine deposits of the u s atlantic coastal plain coupled with paleoclimatic reconstructions based on ostracode marine and pollen continent data document at least five relatively warm intervals during the last 500 000 years on the basis of multiple paleoenvironmental criteria we determined relative sea level positions during the warm intervals relative to present mean sea level were 7 5 meters at 188 000 years ago 7 5 1 5 meters at 120 000 years ago 6 5 3 5 meters at 94 000 years ago and 7 3 meters at 72 000 years ago the composite sea level chronology for the atlantic coastal plain is inconsistent with independent estimates of eustatic sea level positions during interglacial intervals of the last 200 000 years hydroisostatic adjustment from glacial interglacial sea level fluctuations lithospheric flexure and isostatic uplift from sediment unloading due to erosion provide possible mechanisms to account for the discrepancies alternatively current eustatic sea level estimates for the middle and late quaternary may require revision

coastal aminostratigraphy of the last interglaciation in southern australia abstract amino acid racemization data for marine molluscs of the last interglaciation from southern australia provide the basis for a predictive model for relative dating of late quaternary sequences genera analyzed include anadara sp katelysia sp glycymeris sp and fulvia sp that exhibit moderate racemization rates a genus effect on racemization is not evident in these taxa coefficients of variation for intershell d l ratio variation for each deposit are generally less than 12 the extent of racemization in molluscan fossils of the last interglaciation from temperate coastal settings in southern australia represents an exponential function of temperature and is in general accord with data from northern hemisphere sites with similar contemporary mean annual temperature values these data highlight the potential of amino acid racemization for global correlation programs the amino acid data from southern australia suggest however that a larger margin of variation may have to be accounted for in stratigraphic correlation as indicated by the greater scatter of data around the oxygen isotope substage 5e isochron these data have implications regarding the age resolving power of amino acid racemization

quaternary stratigraphy of the draugen area mid norwegian shelf abstract lithostratigraphic biostratigraphic and chronostratigraphic studies on a 130 m long core from haltenbanken mid norwegian shelf dr 88 30 shows sequences of short episodic glacigenic sedimentation and periods of more continuous marine sedimentation the sediment sequence is dated by palaeomagnetism as well as the amino acid and the strontium isotope methods back to ca 1 1 ma previous seismostratigraphic interpretations placed the regional pliocene pleistocene boundary at ca 90 m depth at the core site this level was dated to be of brunhes matuyama age the study area has been covered by grounded glaciers at least five times during the last 1 1 ma the first expansion of the scandinavian ice sheet was at ca 1 1 ma depositing a diamicton these sediments are overlain by a long sequence of normal marine sediments deposited during both glacial and interglacial conditions two interglacial periods from this sequence have been given an informal interglacial notation except for the glaciation at ca 1 1 ma the glacials during the early pleistocene which are identified in the core were relatively limited a transition to more extensive glaciations occurs in the early middle pleistocene during these more extensive glacial phases major erosion took place along the inner continental shelf this erosional phase resulted in overdeepening of the inner shelf which during the middle and late pleistocene influenced the depositional dynamics in the central and the outer part of the shelf in the study area the middle and late pleistocene periods are dominated by glacigenic sediments with only very thin interglacial sediments occasionally preserved one interglacial period from the middle pleistocene has been given an informal interglacial notation the core has been correlated to cores from the north sea basin on the basis of amino acid stratigraphy and palaeomagnetism the lithological and the foraminiferal stratigraphy indicates a synchronous appearance of the major lithological units and of the fauna assemblages in these areas

aspartic acid racemization dating of holocene brachiopods and bivalves from the southern brazilian shelf south atlantic abstract the extent of racemization of aspartic acid asp has been used to estimate the ages of 9 shells of the epifaunal calcitic brachiopod bouchardia rosea and 9 shells of the infaunal aragonitic bivalve semele casali both taxa were collected concurrently from the same sites at depths of 10 m and 30 m off the coast of brazil asp d l values show an excellent correlation with radiocarbon age at both sites and for both taxa r2site 9 b rosea 0 97 r2site 1 b rosea 0 997 r2site 9 s casali 0 9998 r2site 1 s casali 0 93 the asp ratios plotted against reservoir corrected ams radiocarbon ages over the time span of multiple millennia can thus be used to develop reliable and precise geochronologies not only for aragonitic mollusks widely used for dating previously but also for calcitic brachiopods at each collection site bouchardia specimens display consistently higher d l values than specimens of semele thermal differences between sites are also notable and in agreement with theoretical expectations as extents of racemization for both taxa are greater at the warmer shallower site than at the cooler deeper one in late holocene marine settings concurrent time series of aragonitic and calcitic shells can be assembled using asp racemization dating and parallel multi centennial to multi millennial records can be developed simultaneously for multiple biomineral systems

aminostratigraphy of peruvian and chilean quaternary marine terraces amino acid enantiomeric ratio d l data for over 200 molluscs from pleistocene marine terraces on the coast of peru and chile are reported they are used to evaluate the utility of this dating method for terraces in this region analyzed samples represent both local relative age sequences and regionally correlative deposits identified over a broad latitude range 14 310s aminozones are defined on the basis of data for protothaca supplemented with results for mulinia and other genera electron spin resonance esr data serve to calibrate two aminozones from peru ca 15 s as being correlative with oxygen isotope stages 5 and 7 of the marine isotope record the latitudinal trends of enantiomeric ratios for stage 5 samples plotted against current mean annual temperature cmat are similar to those observed for protothaca from the north american pacific coast the sea level record preserved in the peru chile terraces is complex and usually not clearly resolved geomorphically typical uplift rates of 0 1 0 2 m ka are inferred from terrace age and elevation data with higher rates being observed where the nazca ridge is being subducted beneath the coast at about 15 s evidence of terrace reoccupation by sea levels with substantially different ages is found at several sites of apparent low uplift

bio and aminostratigraphy of some quaternary marine deposits in west greenland 14c dates and the geological setting of quaternary marine deposits from three sites in west greenland indicate a pre holocene age the mollusc faunas at the sites are distinctly different although

enhanced age resolution of the marine quaternary record in the arctic using aspartic acid racemization dating of bivalve shells abstract aspartic acid asp racemization occurs at a significantly higher rate than isoleucine epimerization and consequently provides better temporal resolution of arctic marine deposits from alaska spitsbergen and baffin island heating experiments at 100 c on the bivalvesmyaandhiatellashow the asp racemization rate decreases with increasing d l values as is typical for biogenic carbonates based on these experimental racemization rates and rates determined from racemization of samples radiocarbon dated to ca 10 000 12 000 yr b p activation energies formyaandhiatellaare estimated to be 30 6 and 30 0 kcal mol respectively for asp racemization and 29 0 and 29 5 for isoleucine epimerization analysis of a time series of plio pleistocenehiatellafrom the north coast of alaska shows that last interglacial mollusks can be readily distinguished from modern samples by asp but not by isoleucine d l asp values indicate a younger age for the fishcreekian transgression than does isoleucine epimerization for spitsbergen d l asp shows a slight age difference ca 12 000 yr between two units of the episode b interstadial and suggests that the age of these units may be closer to 65 000 than to 80 000 yr b p two possible ages suggested by other evidence the age of the loks land interstadial on baffin island is likely to be greater than that indicated by radiocarbon ages within deposits from each region d l asp values are less variable among individual shells than isoleucine epimerization values this may indicate better reliability of asp for geochronology

130 000 yr continuous pollen record from clear lake lake county california pollen analysis of a 115 m sediment core from clear lake lake county california provides a climatic record that is continuous for the past 130 000 yr the pollen record reflects migrations of the tree species of the california coast ranges in response to the climatic changes of the last glacial cycle during interglacials the clear lake pollen rain was dominated by quercus oak pollen during cooler periods oak pollen was replaced by pollen of coniferous species the curve for quercus pollen strongly resembles and is used to correlate with both deep sea oxygen isotope curves and the climatic record from certain european pollen studies

dating pleistocene archeological sites by protein diagenesis in ostrich eggshell eggshells of the african ostrich struthio camelus ubiquitous in archeological sites in africa have been shown by laboratory simulation experiments to retain their indigenous organic matrix residues during diagenesis far better than any other calcified tissue yet studied the rate of l isoleucine epimerization to d alloisoleucine follows reversible first order kinetics and has been calibrated for local temperature effects and used to estimate the age range of stratified archeological sites age estimates are consistent with radiocarbon dates from several stratified archeological sites with adequate calibration this technique can provide accurate ages to within 10 to 15 percent for strata deposited within the last 200 000 years in the tropics and the last 1 000 000 years in colder regions such as china

morphometric analysis and amino acid geochronology of uplifted shorelines in a tectonic region near reggio calambria south italy the tectonic coastline of the calabrian peninsula provides an opportunity to study the morphology and history of elevated marine shorelines near capo dell armi eleven shorelines are preserved between sea level and 256 m with some correlation difficulties posed by the dissection of the area by intermittent streams we are able to correlate several of the shorelines across the entire study area with the support of correlations provided by amino acid geochronology we have identified four shorelines dating from the last interglacial period isotope stage 5 the oldest two both contain the strombus bubonius fauna and are of indistinguishable early last interglacial ages stage 5e aminozone e ca 125 ka the highest terrace vii is associated with a shoreline at 157 m and the lower with a shoreline around 125 105 m a s l of the two younger stage 5 without strombus bubonius the higher v lies at about 90 100 m and produces amino acid ratios slightly younger than but statistically indistinguishable from those of aminozone e however the youngest last interglacial shoreline deposits iv have produced amino acid ratios correlated to late stage 5 5a elsewhere in the mediterranean basin amino acid and geomorphic data have shown that uplift varies the study area from 0 85 to 1 03 m ka and suggeststhat constant uplift along any one traverse is unlikely