stable oxygen and carbon isotopes in late glacial holocene freshwater carbonates from belarus and their palaeoclimatic implications abstract four sets of 18 o and 13 c curves were derived from late glacial to mid holocene spring and lacustrine carbonates from belarus stratigraphic division was carried out by palynological studies and 14 c dating it was revealed that variations of isotopic compositions and the dynamics of terrestrial vegetation were affected to some extent by common climatic forcing birch expanded during relatively warm and or arid phases higher 18 o and or 13 c fir spread during relatively cold and or humid phases lower 18 o and or 13 c and grasses were abundant during relatively cold lower 18 o or arid phases higher 13 c a comparison of four pairs of 18 o and 13 c curves allowed the recognition of several palaeoclimatic events at a regional scale two main cold events interrupted by a warmer interval occurred in the younger dryas a short term episode of active permafrost decay at the end of the younger dryas and in the very beginning of the preboreal caused an abrupt rise of lake levels followed by their rapid fall a shift toward a lower precipitation evaporation balance and lower lake levels took place roughly in the middle of the boreal a trend of decreasing temperatures throughout most of the boreal culminated in a short lived very cold phase at 8100 14 c year bp or 9050 cal 14 c year bp according to the proposed age model in the atlantic 1 warmer phases were coincident with the phases of the lower precipitation evaporation balance an episode of significant short term warming occurred in the last third of the atlantic 1 correlation of the 18 o curve derived from authigenic calcites precipitated between the beginning of the preboreal 2 and the end of atlantic 1 in the ptich river valley with that from the gisp2 greenland ice core allowed good matching of the trends and spikes i e of the air temperature changes under assumption that the ages of the ptich pollen based time model are 600 1000 years too old

lateglacial vegetation dynamics in the eastern baltic region between 14 500 and 11 400 cal yr bp a complete record since the bolling gi 1e to the holocene abstract this paper discusses a complete record of vegetation history since the bolling gi 1e warming 14 500 cal yr bp up to the holocene in latvia to date this is the only complete record of such age in the eastern baltic area and the northernmost area for which bolling records are present combining pollen evidence pollen accumulation rates par and plant macrofossil data we assess the local and regional vegetation development and we attempt to separate the true lateglacial vegetation signal by removing the obviously redeposited thermophilous pollen however we remove not only their signal we discuss the possibilities of separating the redeposition signal of the so called local lateglacial trees pine and birch by looking at their corrosion and degradation the results show that the bolling warming in the eastern baltic area was a treeless tundra community consisting of the shrubs betula nana dryas octopetala and salix polaris the older dryas cold spell is clearly recognised as a decline in the total concentration of plant macrofossils and pars at between 14 200 and 13 500 cal yr bp at 13 460 cal yr bp the b nana macrofossils disappear and tree birch betula sect albae appears marking the start of tree birch forest the presence of pine forest is confirmed by a variety of macrofossils including bark wood needles and seeds since 13 400 cal yr bp at the same time at which pine stomata are found the first identified pine stomata finds are associated with a pinus par over 3000 grains cm 2 yr 1 and pine macrofossil finds with a pinus par over 4000 grains cm 2 yr 1 during the warmest period of the gi 1a allerod at 13 000 12 700 cal yr bp a pine forest with deciduous trees birch betula pendula and aspen populus tremula developed in the study area the younger dryas gs 1 cooling strongly affected the floral composition in eastern latvia the par of the tree taxa declined abruptly from a maximum value at 12 700 to below 1000 grains cm 2 yr 1 at 12 600 cal yr bp the response time for the pine forest to collapse was 100 years according to the par data pine macrofossils disappear simultaneously with the pollen signal at 12 600 cal yr bp yet occasional pinus stomata are recorded throughout the younger dryas gs 1 the landscape was treeless shrub tundra again with d octopetala s polaris b nana and juniperus present picea is introduced in the region within the cold younger dryas and is represented by stomata 12 400 12 200 cal yr bp needles seeds and wood since 12 050 cal yr bp up to the holocene the pleistocene holocene boundary at 11 650 cal yr bp is marked by changes both in vegetation composition and sediment type the organic rich gyttja accumulated instead of silts and clays and the start of the holocene warm period permitted forest re expansion in eastern latvia

late glacial climatic and environmental changes in eastern central europe correlation of multiple biotic and abiotic proxies from the lake svarcenberk czech republic thick lake sediments discovered in the southern part of the czech republic provide a high resolution archive for detailed study of paleoenvironmental changes during the late pleistocene to holocene in eastern central europe until recently no similar records were available for this important region in the transition from oceanic to continental macro climatic settings using a multi proxy approach that combines sedimentological pollen analytical paleozoological chironomids geochemical and mineral magnetic methods we demonstrate that major climatic events of the late glacial can be correlated with atlantic rather than continental regimes as reported in paleoclimatic literature for the area of the interest the sensitivity of applied biological and abiological techniques to climatically driven processes allows trans regional comparisons and enables us to discuss the pattern of geographic variation in these processes we are able to establish a clear relationship between vegetation cover soil development and erosional processes a short term intra allerod cool event has been correlated with the gerzensee oscillation proxy evidence suggests that the early half of the younger dryas was rather humid whereas the latter half was dry and had significant impact on vegetation sedimentary dynamics and lake level status during the yd preboreal transition

mobility of rare earth and other elements during crystallization of peralkaline silicic lavas abstract pantellerite lavas of the dormant caldera volcano mayor island new zealand have thick nonhydrated obsidian selvages at the tops and bases and crystalline microspherulitic interiors the flows were chemically homogeneous on emplacement but the crystalline portions have lost significant na f cl cs y and ree percentage losses of y and ree may exceed 60 ce yb ratios decrease by as much as 20 but eu eu ratios are unchanged loss of y and ree is attributed to the expulsion at near solidus temperatures of y ree 3 chloride complexes but other complexing agents may have contributed to this mobility na is also lost in the same manner groundwater has introduced mg and sr and leached or redistributed na cs and halogens analysis of hydrated glassy plinian pumice shows that secondary hydration has not affected y and ree concentrations the elements na mg f cl sr cs y and ree are highly mobile during the crystallization of peralkaline silicic melts and should not be used in petrogenetic evaluations these elements but not y and ree are also redistributed during secondary hydration processes magmas of undersaturated peralkaline composition will be similarly affected

climatic forcing of carbon oxygen isotopic covariance in temperate region marl lakes carbon and oxygen stable isotopic compositions of lacustrine carbonate from a southeastern michigan marl lake display linear covariance over a range of 4 0 peedee belemnite pdb in oxygen and 3 9 pdb in carbon mechanisms of delta 13 c delta 18 o coupling conventionally attributed to lake closure in arid region basins are inapplicable to hydrologically open lake systems thus an alternative explanation of isotopic covariance in temperate region dimictic marl lakes is required we propose that isotopic covariance is a direct record of change in regional climate in short residence time temperate region lake basins summer meteoric precipitation is enriched in 18o relative to winter values and summer organic productivity enriches epilimnic dissolved inorganic carbon in 13c thus climate change toward longer summers and or shorter winters could result in greater proportions of warm month meteoric precipitation longer durations of warm month productivity and net long term enrichment in carbonate 18o and 13c isotopic covariance observed in the michigan marl lake cores is interpreted to reflect postglacial warming from 10 to 3 ka followed by cooler mean annual temperature a shift toward greater proportions of seasonal summer precipitation a shortening of the winter season or some combination of these three factors

the new england batholith constraints on its derivation from nd and sr isotopic studies of granitoids and country rocks abstract nd and sr isotopic compositions are reported for the granitic suites which comprise the late palaeozoic to earliest mesozoic new england batholith of eastern australia some of the granitic suites are typically i type in their mineralogy chemistry and isotopic compositions implying a derivation from igneous infracrustal source rocks whereas other suites have characteristics consistent with a derivation from a protolith which was predominantly sedimentary and relatively felsic s types the i type granitoids of the nundle suite have nd values 3 3 to 6 1 that are amongst the most primitive yet documented for a relatively felsic sio 2 65 plutonic suite and these values imply a derivation from either a depleted upper mantle source or more probably a complex source region involving both volcanic arc rocks and detrital material their compositions are distinctly more primitive than those of the new england super suite which constitutes the permian core of the batholith this extensive super suite comprising granitoids traditionally designated as i type has an overall range in initial nd and sr isotopic compositions of 1 7 to 4 6 and 0 70458 to 0 70624 respectively although the majority of plutons have initial nd isotopic compositions which fall into a very narrow range 1 0 1 5 units this limited range is remarkable considering the extreme lithological diversity and range in chemical composition of the analysed samples sio 2 47 74 and implies a source region of considerable volume having reasonably uniform isotopic compositions but variation in chemistry a similarly uniform source isotopically is also indicated for the s type granitoids of the carboniferous hillgrove suite and carboniferous permian bundarra suite with initial nd values of 0 8 to 2 3 and initial 87 sr 86 sr compositions of 0 70474 to 0 70577 showing only limited ranges five pelites three felsic and four mafic greywackes representing typical country rocks from different stratigraphic levels have initial nd values 1 7 to 6 6 and initial 87 sr 86 sr compositions 0 70378 to 0 70585 which essentially mirror the compositional variation in the granitoids a chemical mineralogical and isotopic bimodality in these sediments indicates two very distinctive sources one felsic rhyodacitic the other relatively mafic andesitic which were separated spatially and temporally in many but not all areas of early to mid palaeozoic new england a model is presented in which the s type granitoids are derived from a predominantly felsic source i e pelites and felsic greywackes whereas some of the granitoids belonging to the new england super suite may have been derived from source rocks consisting of both felsic and mafic sedimentary components the distinction between many s type and i type granitoids in new england is unclear for two principal reasons a because the granitoids and their respective source rocks are relatively young geologically so that their isotopic systems have not evolved to any considerable extent and b because of the intrinsic igneous chemical compositions of any sedimentary component that may be involved in their genesis

microbial origin of early animal trace fossils abstract elongate surface trails that abound in late ediacaran and early paleozoic sandstone and siltstone are often attributed to early animals these trails commonly exist on the same beds as wrinkle structures millimeter to centimeter size ridges and pits that are interpreted as evidence of the former presence of microbial mats here we show that interactions between oscillatory flow and centimetric microbial aggregates produce elongate trails on the surface of a sediment bed trails left by moving microbial aggregates share a number of characteristics with some presumed trace fossils of the earliest animals elevated edges zig zag patterns smooth curves reversals intersections with other trails series of pits and paths that terminate abruptly and restart nearby under the same flow conditions millimetric microbial aggregates generate wrinkle structures thus the interaction between flow and microbial aggregates on a sediment bed can produce a number of structures that are commonly interpreted as evidence of early animal locomotion

isotopic and geochemical composition of marl lake waters and implications for radiocarbon dating of marl lake sediments radiocarbon dates on organic and calcareous fractions of sediment cores from marl lakes may yield anomalous ages due to the assumption of a constant hardwater correction factor along the sediment sequence a study of eight marl lakes in southern ontario that are actively precipitating calcium carbonate was conducted in order to assess those isotopic and aqueous geochemical parameters in modern lakes that may be utilized to estimate the history and extent of variations in the hardwater effect along such sediment sequences results show an increase in the 13c composition of lake dic dissolved inorganic carbon as approach to isotopic equilibrium with atmospheric co2 occurs differences in the extent to which this equilibrium is established also appear responsible for observed differences in the 14c activity of dic between lakes of as much as 20 pmc percent modern carbon these variations have been related to the relative residence times of water in each lake by examination of their corresponding seasona

palynological approach in upper quaternary terrestrial carbonates of central italy anything but a mission impossible a palynological survey has been carried out on two late quaternary travertine s l deposits of central italy at serre di rapolano and bagnoli tuscany region the principal aim was to improve the understanding of factors that affect the accumulation and preservation of pollen grains in thermal i e travertine and ambient temperature i e calcareous tufa terrestrial carbonates for this purpose 52 526 pollen grains belonging to 118 pollen taxa from local to extra regional sources were analysed in 200 samples from different travertine and calcareous tufa lithofacies of these 97 samples generally from thermal travertines were barren in palynomorphs by contrast pollen grains in the remaining samples were well preserved and did not show differential preservation features these observations suggest that the ph of the solutions from which travertine or tufa precipitate is not a limiting factor in causing corrosion and or destruction of pollen grains rather the barrenness recorded in many samples appears to reflect a paucity of pollen rather than post depositional destruction results suggest that the depositional energy of the environment during the deposition of travertine plays an important role in controlling pollen concentration as verified in both depressions lower energy to higher pollen concentration and slopes higher energy to lower pollen concentration respectively analysis of pollen data suggests that relatively high depositional temperatures and rates of carbonate deposition are also major limiting factors for efficient accumulation of pollen grains results of this study reveal that understanding pollen taphonomy processes in travertine and calcareous tufa is critical to developing accurate palaeoenvironmental and palaeoclimatic reconstructions

lateglacial and early holocene environmental dynamics in northern lithuania a multi proxy record from ginkūnai lake abstract to reconstruct the lateglacial and early holocene palaeoenvironmental dynamics in the northern part of lithuania the sediment record from gink nai lake was studied applying a multi proxy approach involving pollen diatom and plant macrofossil surveys as well as 18 o 13 c 14 c and loss on ignition loi measurements together with geochemical investigations the obtained data suggest the deglaciation of the area started at approximately 16 000 16 500 cal bp followed by the formation of a tree less tundra the obtained palaeobotanical records indicate the scarcity of the vegetation cover and the flourishing of the non arboreal taxa in the local flora suggesting a severe climatic regime after 13 700 cal bp the pinus betula predominating forest progressively expanded although this process was partly reversed during the recurrence of a cold interval recorded from 13 000 to 13 100 cal bp since 12 600 cal bp rapid aridification of the climatic regime reflected in the isotope record was accompanied by the formation of cold adapted vegetation including picea stands which acted as an intensive supply of allochthonous material into the basin thereby decreasing the water level the identified period of physical disturbance lasted until approximately 11 800 cal bp significant changes of the palaeoenvironmental regime subsequently occurred in the area and were manifested in most of the obtained proxies i e changes in the sediment type transformations of the vegetation cover and fluctuations of the sedimentation regime isotope records along with the geochemical data indicate a major climatic turn in terms of the temperature and moisture after 11 500 cal bp the rising productivity of the basin was coincident with the stabilisation of the soil layer and the formation of dense vegetation cover enriched by corylus ca 9800 cal bp and ulmus ca 10 300 cal bp during the early holocene after 10 800 cal bp the investigated part of the basin changed to a peat bog

evidence for cnidaria like behavior in ca 560 ma ediacaran aspidella the first appearance of animals in the geological record is a matter of continuing debate how deep were the roots of the cambrian explosion molecular clock estimates indicate that the deepest divergences of the metazoa had occurred by the ediacaran period 635 541 ma yet evidence of animal activity from well below the ediacaran cambrian boundary has been rare and often questionable meanwhile the ediacaran macrobiota has remained enigmatic as emphasized by recent controversial claims that south australia ediacaran forms were not marine animals at all but land based lichens and microbial colonies here we report evidence for animal like behavior in a submerged setting in a key ediacaran form aspidella terranovica billings 1872 a discoidal fossil from the ca 560 ma fermeuse formation of newfoundland canada we describe sedimentary fabrics indicating progressive vertical movement of an organism through sediment in response to an aggrading sediment water interface such equilibrium traces are familiar from the phanerozoic and are observed in partially buried marine animals such as tube anemones today furthermore horizontal trails closely comparable to trails previously described from 565 m y old mistaken point newfoundland are now linked to aspidella our findings constitute evidence of both vertical and horizontal movement in a key ediacaran taxon consistent with an animal of cnidarian grade moreover because aspidella is also reported from the rawnsley quartzite of south australia our evidence conflicts with the proposed radical interpretation of that ediacaran fossil assemblage we demonstrate that at least some ediacaran forms were probably early animals and that they lived underwater

holocene climatic instability a prominent widespread event 8200 yr ago the most prominent holocene climatic event in greenland ice core proxies with approximately half the amplitude of the younger dryas occurred 8000 to 8400 yr ago this holocene event affected regions well beyond the north atlantic basin as shown by synchronous increases in windblown chemical indicators together with a significant decrease in methane widespread proxy records from the tropics to the north polar regions show a short lived cool dry or windy event of similar age the spatial pattern of terrestrial and marine changes is similar to that of the younger dryas event suggesting a role for north atlantic thermohaline circulation possible forcings identified thus far for this holocene event are small consistent with recent model results indicating high sensitivity and strong linkages in the climatic system

stable isotope record of palaeoclimatic change in a british holocene tufa a 9 5 m long continuous core through holocene tufa deposits in derbyshire uk was analysed for oxygen and carbon stable isotope variations with a view to palaeoclimatic and palaeoenvir onmental interpretation the depositional environment of the tufa is well understood and dated using 14c and biostratigraphy it is argued that smooth variations of up to 1 in 18o of the tufa calcites are caused by changes in the isotopic composition of regional rainfall which in turn were caused mainly by changes in air temperature palaeoclimate in general lower 13c values for calcite correspond with higher 18o values suggesting a stronger component of soil derived carbon during warmer climatic phases a stable isotope approach to reading terrestrial palaeoclimatic records is of widespread application to holocene and older tufa deposits which are common in carbonate bedrock regions

the gisp2 δ18o climate record of the past 16 500 years and the role of the sun ocean and volcanoes measured 18o 16o ratios from the greenland ice sheet project 2 gisp2 ice core extending back to 16 500 cal yr b p provide a continuous record of climate change since the last glaciation high resolution annual 18o 16o results were obtained for most of the current millennium a d 818 1985 and record the medieval warm period the little ice age and a distinct 11 yr 18o 16o cycle volcanic aerosols depress central greenland annual temperature 1 5 c maximally and annual 18o 16o for about 4 yr after each major eruptive event on a bidecadal to millennial time scale the contribution of solar variability to holocene greenlandic temperature change is 0 4 c the role of thermohaline circulation change on climate problematic during the holocene is more distinct for the 16 500 10 000 cal yr b p interval analogous to 14c age calibration terminology we express time in calibrated cal yr b p a d 1950 0 cal yr b p the oldest dryas bolling older dryas allerod younger dryas sequence appears in great detail bidecadal variance in 18o 16o but not necessarily in temperature is enhanced during the last phase of lateglacial time and the younger dryas interval suggesting switches of air mass transport between jet stream branches the branched system is nearly instantaneously replaced at the beginning of the bolling and holocene at 14 670 and 11 650 cal yr b p respectively by an atmospheric circulation system in which 18o 16o and annual accumulation initially track each other closely thermodynamic considerations of the accumulation rate temperature relationship can be used to evaluate the 18 o 16o temperature relationship the gisp2 ice layer count years of major gisp2 climate transitions also support the use of coral 14c ages for age calibration

pollen and oxygen isotope analyses on late and post glacial sediments of the tourbiere de chirens dauphine france the sequence of vegetation phases in the late glacial was studied in a sediment section from the bog tourbiere de chirens by means of pollen analysis 18o16o ratios of samples of lacustrine marl obtained from the same profile reflect variations of 18o16o in precipitation and thus provide an additional independent paleoclimatic record the observed 18o16o variations agree well with the climatic history as deduced from pollen analysis the climatic transition from the oldest dryas to the bolling period sensu lato as well as the beginning and end of the younger dryas cold phase is marked by abrupt changes in the 18o16o ratio which were observed also in other regions of the alps these drastic climatic changes probably took place simultaneously over large areas of central europe and occurred within short time spans

oxygen isotope disequilibrium precipitation of calcite in lake arreso denmark lake carbonates are generally assumed to precipitate at or very close to oxygen isotopic equilibrium with the ambient water we present results from the eutrophic lake arreso northeastern sealand denmark that demonstrate disequilibrium precipitation of present day calcite according to the temperature equation of epstein et al these calcites are depleted in 18 o by 2 3 when compared to the expected equilibrium values core studies indicate that the development of disequilibrium conditions in lake arreso is correlated with the onset of an enhanced eutrophication a high precipitation rate is suggested as the mechanism responsible for the observed 18 o depletion of the calcite precipitates

climate and vegetation dynamics in the tundra and forest zone during the late glacial and holocene abstract analysis of palynological successions has enabled reconstruction of climate variations throughout the late glacial and holocene in the tundra and forest zones of northern eurasia statistical analysis allows estimation of mean annual precipitation and mean annual and july temperatures based on palynological assemblages thus the dynamic relationships between climate and vegetation changes can be established throughout the late glacial and holocene climate fluctuations were more dramatic in eastern europe than in siberia primarily as a result of the influence of westerly air masses in contrast the autochthonous climate of siberia dominated by local air masses was less prone to influence from climate changes elsewhere in the northern hemisphere and shows only an attenuated younger dryas signal mid holocene warming characterizes all of northern eurasia although the regions of siberia most influenced by continental climates show less pronounced cooling during the later holocene sharp changes between summer monsoonal and winter anti cyclonic regimes characterize the pacific maritime region

origins of elements building travertine and tufa new perspectives provided by isotopic and geochemical tracers fluid rock interaction represents a major process in the formation of calcitic or aragonitic travertine and tufa catt in most cases catt is associated to limestone dissolution somewhere along the hydrogeological pathway however a wide array of other substratum basalts rhyolites carbonatites ultramafics granites dolomites evaporites can act as potential source of elements involved in the formation of catt this study reports on the evaluation of potential geochemical tracers linking catt to their substratum and unravelling the origin of elements a large database was established from available literature data as well as new data acquired in the frame of this study for a set of modern to recent catt ligurian ophiolites italy the chaine des puys limagne graben and paris basin france reunion island indian ocean jebel oust tunisia four most reliable tracing methods are identified 1 13c and 18o cross plot allows distinguishing epigean min 13c 27 2 max 13c 0 9 mean 13c 12 3 for n 314 from hypogean systems min 13c 4 max 13c 11 7 mean 13c 2 87 for n 198 very low 13c values 4 associated to negative 13c values are specifically indicative of an ultramafic source rock 2 barium and strontium cross plot helps to discriminate different groups of source rocks amongst the hypogean catt i source rocks composed of mixed limestones evaporites and dolomites are characterised by low barium 400 ppm contents ii mafic and granitic source rocks are undifferentiated and display similar barium from 15 to 930 ppm and high strontium 200 ppm contents iii the carbonatite group is characterised by its exceptional high barium and strontium values in epigean catt a pure limestone source rock usually relates to very low barium and strontium contents 50 ppm 3 relatively high beryllium content 30 ppm in catt seems to indicate a pure granitoid source 4 high chromium concentrations 20 ppm are systematically documented in modern catt located on an ultramafic substratum the definition of diagnostic compositional fields for actively forming or recently formed catt is influenced by many factors including water composition water temperature dissolved gas composition and concentration biological activity position in the sedimentary body and early diagenesis in addition to substratum lithology however the results of this study illustrate that despite these many factors the combined use of ba sr be cr 13c and 18o may be valuable to discriminate the rock lithology prevailing in the hydrogeological or palaeo hydrogeological reservoir of catt

post glacial environmental history in ne poland based on sedimentary records from the dobrzyn lakeland this paper presents a comprehensive palaeoenvironmental data set from a trough between glacial curvilineations an intra gcl trough of the dobrzyn lake district north central poland a sediment core taken from the depression was investigated to reconstruct late glacial and holocene environmental changes in north central poland using a combination of palynological macrofossil sedimentological and geochemical studies four main development phases of the studied intra gcl trough were distinguished accumulation of the analysed sediments occurred from the late vistulian glacial phase through the late glacial to present times our data suggest the persistence of dead ice in the basin up to the older dryas lacustrine phase the sedimentary record of the depression reflects a considerable difference between the late glacial early holocene and the middle late holocene in terms of environmental conditions the late glacial was characterised by rapid environmental changes while climatic conditions throughout the holocene were relatively stable except for the subboreal period a small lake was strictly dependent on climatically controlled vegetation changes and erosion tendencies in the vicinity of the zbojenko site the lake finally disappeared at the turn of the younger dryas and the preboreal period the preboreal boreal and atlantic periods encompassed the early paludical phase during which the water level used to rise and hence the mire could be flooded the area was covered with dense vegetation and the rate of denudation processes around the site was moderate the late paludical phase included the subboreal and most of the subatlantic deciduous forests with quercus carpinus corylus dominated around the site major changes occurred between the late subboreal and the early subatlanic as a result of the growing human impact on the environment the subatlantic ends with the human impact phase middle age dominated by human impact little accumulation of sediments and highly increased denudation

short term changes in a saalian glacial lake the parchliny c site central poland abstract the paper discusses results of sedimentological faunal molluscs ostracods and geochemical studies of an 80 cm thick rhythmite succession within a glaciolacustrine sequence 8 10 m in thickness of the awki formation exposed at the parchliny c site in the tectonically active kleszczow graben central poland sedimentological studies show the predominance of rhythmically deposited pale grey muds 2 0 7 cm thick and black clays 0 5 5 cm thick the pro glacial sediments have yielded the first examples of saalian molluscan and ostracod communities to be recorded from europe and probably globally the presence of a lake basin is confirmed by the freshwater species fauna candona neglecta cypridopsis vidua fabaeformiscandona protzi limnocythere inopinata limnocytherina sanctiparicii cyclocypris laevis metacypris cordata ostracods and anodonta cygnaea ancylus fluviatilis theodoxus fluviatilis bithynia tentaculata valvata piscinalis and pisidium sp molluscs suggestive of deposition during a period of colder climatic conditions although some species might be indicative of a warmer period resembling an interglacial the whole section has a high carbonate content up to several tens percent the carbonates are enriched in the heavy isotope of oxygen the isotopic composition of carbon and oxygen indicates two stages of lake development the transition of the lake from a hydrologically open to a closed system with significant evaporation has been reconstructed from correlation of 13c and 18o sedimentological faunal molluscs ostracods and stable isotope studies of the saalian awki formation have revealed an important snapshot a 14 year record in the hydrological transformation of this specific pro glacial lake system

tilting marks a wave produced tool mark resembling a trace fossil abstract small waves can move by repeated tilting objects over considerable distances oblique to nearly parallel to wave crests this was observed for dead gaping articulated bivalves of the genus mytilus only larger than average waves about every 20th wave affected the shells but even these waves did not actually reach the sediment surface the wave energy led to a right left tilting and a small lateral shift of the bivalve producing a sedimentary structure tilting mark by pushing aside the sediment when tilted tilting marks typically consist of symmetrical walls and a central furrow displaying a transverse ornamentation tilting marks resemble the lower part of the trace fossil scolicia and could be misinterpreted as such tilting marks were observed in very shallow water

were fossil spring associated carbonates near zaca lake santa barbara california deposited under an ambient or thermal regime abstract a previously undescribed succession of currently inactive spring associated carbonates located near zaca lake southern california was investigated in order to determine the nature of deposition ambient temperature or hydrothermal water as both are found within the region the carbonate deposits are up to 1 m thick and formed discontinuously for over 200 m in a narrow valley between two ridges that drain miocene monterey formation bedrock depositional facies along the presently dry fluvial path include barrage deposits narrow fluvial channels and cascade deposits the carbonates are mesoscopically banded and contain ubiquitous micro to macrophyte calcite encrusted fabrics all of the depositional facies contain alternating bands 05 mm to 5 mm thick of dark brown and light brown isopachous calcite the dark brown bands are composed of dense isopachous bladed calcite whereas the light brown bands are composed of bundles of calcite tubules interpreted as the biosignature of the desmid microalgae oocardium stratum oxygen isotope thermometry utilizing modern water 18 o values from the piped spring reveal depositional water temperature estimates that collectively range from 11 to 16 c stable isotope carbon values exhibit a mean 13 c value of 9 01 0 62 1 n 27 our petrographic and geochemical data demonstrate that 1 inactive carbonates were likely sourced from ambient temperature water with a strong soil zone 13 c signal 2 the oocardium calcite biosignature can be used to infer depositional temperature and flow conditions and 3 the occurrence of extensive carbonates especially the presence of a perched cascade deposit indicate the carbonates formed when conditions were much wetter

downstream changes in the lithology and grain size of fluvial gravels the watarase river japan evidence of the role of abrasion in downstream fining two processes have been considered to explain downstream grain size reduction in gravel bed rivers hydraulic sorting by which finer grains are transported faster and farther than coarse grains and abrasion by which individual particles are diminished in size most studies on the cause of downstream fining in rivers emphasize hydraulic sorting as the dominant fining mechanism however broken boulders are often observed in the bed material of japanese rivers also grain size changes may be correlated with the difference in resistance to breakdown among lithologies the purpose of this study is to use the lithologic composition of bed material on the watarase river to demonstrate that some downstream fining cannot be explained by hydraulic sorting alone the study reach on the watarase river flows on a dissected alluvial fan which means that the river is no longer aggrading the study reach is influenced only slightly by input of gravel from tributaries bed gravel in the study reach consists of several lithologies andesite quartz porphyry sandstone hornfels and chert the grain size distribution and lithology of the river bed material were examined at nine sites there are two principal results 1 size distribution of the gravel is strongly related to lithology andesite boulders or large cobbles make up the framework sizes in the upstream part of the study reach while chert pebbles make up the framework sizes in the downstream part there are few andesite pebbles or chert boulders in the river bed 2 longitudinal changes in the composition of each size class show selective transportation by lithology in every gravel size because the mobility of gravel depends mainly on its size hydraulic sorting by lithology does not occur within the same size class these results indicate clearly that particle abrasion occurs in the watarase river and is responsible at least in part for the downstream decrease in particle size of bed material

the hohonu batholith of north westland new zealand granitoid compositions controlled by source h 2 o contents and generated during tectonic transition geochemical studies on the hohonu batholith of the west coast south island new zealand have recognised two distinct but chemically related suites of mid cretaceous granitoids the suites are characterised by restricted radiogenic isotopic compositions sr i 0 7062 to 0 7085 nd i 4 4 to 6 1 and represent melting of a mafic lithosphere source followed by interaction with ordovician metasediments the two suites te kinga suite and deutgam suite are distinguished by contrasting contents of al2o3 na2o sr ba eu and hree attributable to different residual asssemblages controlled by differing h2o contents during melting of a metabasaltic source the relatively mafic metaluminous i type deutgam suite represents magmas derived by dehydration melting in equilibrium with an amphibolitic plagioclase amphibole residue in contrast the peraluminous high silica compositions of the te kinga suite were produced by melting at higher h2o contents reducing the stability of plagioclase and resulting in a melt in equilibrium with a plagioclase free eclogitic garnet amphibole residue residual plagioclase during generation of the deutgam suite resulted in lower al2o3 na2o sr ba and eu contents whereas residual garnet during generation of the te kinga suite resulted in depleted hree contents the mid cretaceous granitoids of the hohonu batholith were generated during a period of rapid tectonic transition from crustal thickening during collision to crustal thinning and core complex formation during extension

permian gondwana boreal antitropicality with special reference to brachiopod faunas in a reconstructed global permian marine biogeographic framework antitropicality is defined as a biogeographic phenomenon whereby a taxon occurs only in the boreal and gondwanan realms and is lacking completely or nearly so in the intervening palaeoequatorial realm we recognise three types of antitropical distributions bipolar high latitude generally 50 latitude in each hemisphere bitemperate approximately between 30 and 50 latitudes in each hemisphere and a combination of both evidence of permian antitropicality has been reported from almost all major marine invertebrate groups both pelagic or benthic forms and is best known at the generic level although an increasing number of antitropical species have also been recognised antitropicality appears to have occurred throughout most of the permian but its strength varied from stage to stage judging by the number of brachiopod genera shared between the two hemispheres the phenomenon manifests itself most strongly from the sakmarian to the kazanian wordian suggesting a prolonged interval of enhanced biotic interchanges between the gondwanan and boreal realms possible migration pathways and mechanisms are reviewed and discussed among a number of existing scenarios invoked to explain the origin of both modern and geological antitropicality we here present data particularly supporting 1 a south to north stepping stone migratory mechanism via island terranes scattered in the eastern palaeotethys 2 a vicariance model exemplified by the spatio temporal distribution of tomiopsis and 3 a shelf north to south migration along the western coast of the palaeotethys as suggested by sowerbina in addition we also consider dispersal along the western coast of pangea facilitated at times by upwelling systems as an additional migration pathway for intercontinental biotic exchanges during the permian although corroborating data are required at present

provenance of the sedimentary rakaia sub terrane torlesse terrane south island new zealand the use of igneous clast compositions to define the source abstract the permian to late triassic rakaia sub terrane part of the torlesse superterrane of the new zealand eastern province is an accretionary complex that comprises an enormous volume of quartzofeldspathic sandstones and mudstones with subsidiary conglomerates plus minor oceanic assemblages the field of provenance analysis has undergone a revolution with the development of single crystal isotope dating techniques using mainly silt to sand sized single mineral grains fine sand and mud may be transported over thousands of kilometres with potential problems for provenance studies reinforcing the need for caution when interpreting provenance evidence from single heavy mineral grains this study focuses on coarser grained rocks notably conglomerates which involve much shorter transport distances and therefore may be used to trace proximal sources a detailed rock sampling programme and geochronological geochemical and sr nd isotope analysis of igneous clasts from four conglomerates boundary creek te moana mckenzie pass and lake hill have broadly characterised the igneous source for the rakaia sub terrane shrimp u pb zircon ages of rakaia sub terrane igneous clasts define three distinct periods of magmatic crystallisation the first period ranges in age from 292 to 243 ma permian to middle triassic with two clusters recognisable a minor early permian one ranging in age from 292 to 277 ma and a major late permian to middle triassic one from 258 to 243 ma all these clasts are confined to the kazanian permian te moana the dorashamian permian mckenzie pass and the carnian late triassic lake hill conglomerates the clasts which are subduction related calc alkaline to high k calc alkaline and metaluminous to peraluminous range in lithology from andesite to rhyolite and their plutonic equivalents many clasts at lake hill have chemical compositions characteristic of partial melts of a source of basaltic composition in equilibrium with amphibole pyroxene garnet adakites indicative of a thick crust in the clast source area the second period comprises carboniferous calc alkaline metaluminous to weakly peraluminous clasts of the permian boundary creek conglomerate ranging in age from 356 to 325 ma the third group consists of two cambrian clasts a monzogranite from te moana c 497 8 ma and a dacite from lake hill c 517 ma geochronology geochemistry and sr nd isotopes of rakaia igneous clasts correlate broadly with those of permian to triassic plutons and volcanics from the amundsen and ross provinces of marie byrd land thus the antarctic sector of the panthalassan margin of gondwana is the probable source for the rakaia sub terranes as opposed to the other postulated sources in eastern australia

inter regional correlation of palaeoclimatic records for the last glacial interglacial transition a protocol for improved precision recommended by the intimate project group the remit of the intimate project of the inqua palaeoclimate commission is to synthesise marine terrestrial andice core data for the north atlantic region during the last glacial interglacial transition lgit ca 13 10c kyr bp ca 15 11 5 ice core kyr bp a major problem however is the di culty of e ecting correlations at a temporal resolution that are adequate for de ning leads and lags between the polar ice terrestrial marine andatmospheric realms the limitations of the d ating andcorrelation method s currently employed are summarised and new quality assurance protocols are proposed these include recommendations on the contextual information that should accompany radiocarbon dates procedures for radiocarbon calibration the use of an eventstratigraphic approach in inter regional correlations andthe more widespreaduse of time parallel marker horizons basedon tephra layers oxygen isotope stratigraphy palaeomagnetic stratigraphy andradiocarbon wiggle matching to underpin the geochronology and correlation of events during the lgit these protocols will be adopted by the intimate project in future international collaborative research and are recommended to other groups working on this important time period 2001 elsevier science ltd all rights reserved

continuous 60 year stable isotopic and earth alkali element records in a modern laminated tufa jaruga river krka croatia implications for climate reconstruction abstract a continuous 60 year record 1938 1998 of stable isotope compositions of carbon and oxygen as well as trace metal mg sr ba concentrations in a laminated calcite crust precipitated in a short artificial tunnel on a non equilibrium groundwater fed karstic river is presented chemical and isotopic records have been compared to hydrometeorological data available for the last 48 years an attempt is made to relate isotopic and geochemical variations in the crust to environmental parameters such as temperature precipitation and changes in vegetation cover as well as to postdepositional recrystallisation of the older crust material isotopic composition of the crust is largely influenced by non equilibrium precipitation which favours the incorporation of isotopically depleted c and o into the carbonate furthermore because of the complicated hydrological situation there is no observable correlation between the stable oxygen isotope composition of water and temperature the result is that the 18 o isotopic thermometers overestimate the measured precipitation temperatures temperatures calculated from mg ca ratios of water and the carbonate match the 18 o palaeotemperatures within 2 4 c in the older part of the crust precipitated before the onset of industrial pollution of the river it was demonstrated that the application of mg palaeothermometry in natural systems where the mg ca ratio of water is influenced not only by temperature but also by other environmental parameters such as precipitation surface runoff groundwater retention time and anthropogenic influences is subject to a large uncertainty up to 10 c

first evidence for locomotion in the ediacara biota from the 565 ma mistaken point formation newfoundland evidence for locomotion in the precambrian fossil record is scant reliable ediacaran trace fossils are all younger than 560 ma and consist of relatively simple horizontal burrows and trails from shallow water deposits here we describe an assemblage of macroscopic locomotory traces from deep water environments at mistaken point southeastern newfoundland canada dated to ca 565 ma these trails extend the record of complex trace fossils back into the earliest avalonian biota our new evidence for large motile organisms on the seafloor at this time suggests that at least some of these early ediacaran organisms whose biological affinities are widely debated could have been muscular and of metazoan grade

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

the preboreal oscillation around the nordic seas terrestrial and lacustrine responses the occurrence of an early preboreal climatic cooling oscillation pbo in lacustrine and glacial records from northwest europe iceland and greenland is reviewed and documented the often subtle response of the proxy records to this oscillation in combination with its short duration make it difficult to detect owing to its chronostratigraphic position between the 10 000 9900 and 9600 9500 14 c plateaux c 11 300 11 150 calendar yr bp it is also difficult to 14 c date with precision we find that the vegetation response to the pbo varies between sites and regions in contrast to the pioneer vegetation in iceland and southern sweden the expanding birch pine forest in germany denmark was more susceptible to deteriorating growing conditions the combined lacustrine tree ring and glacial records imply that the pbo was characterised by cool and humid conditions throughout northwestern and central europe this is documented by vegetation changes decreased aquatic production increased soil erosion increased 2 h and 13 c content in tree rings readvances or stillstands of the ice sheet in norway and finland and ingression of brackish water into the baltic icelandic proxy records from lake sediments and glacial moraines imply cooler conditions than during the previous preboreal period but not as extreme as during the younger dryas greenland records suggest that the early preboreal was characterised by ice readvances as an effect of cool climate and increased precipitation in relation to the younger dryas it was not until the end of the pbo that climate was warm enough to melt the land based ice sheet this preboreal oscillation found on both sides of the nordic seas is interpreted as an effect of increased freshwater forcing on the thermohaline circulation in the nordic seas which is implied by a simultaneous and distinct rise in the atmospheric 14 c 12 c ratio a slow down of the thermohaline circulation may tempor arily have pushed the polar front further south 1997 by john wiley sons ltd preboreal oscillation thermohaline circulation lacustrine records glacial records chronology

tilting marks observations on tool marks resembling trace fossils and their morphological varieties abstract tilting marks defined here as linear tool marks having transverse ornamentation are produced in shallow water when the oscillatory action of waves of short wavelength tilt grounded objects rhythmically in such a way that they move and push sediment aside these tool marks can resemble trace fossils particularly if they are bilaterally symmetrical even asymmetrical objects can produce symmetrical tilting marks because the shape of the mark only depends on the geometry of the ground touching part of the object which may be partially floating objects of either soft or hard consistency such as jellyfish or wood respectively can produce tilting marks tilting marks are normally produced linearly parallel or at an angle to the direction of wave propagation and do not show sharp bends or curves tilting marks can be formed on plane beds as well as rippled surfaces tilting marks can be distinguished from trace fossils by taking into account the geometry symmetry the direction of movement and the mainly linear course and the internal pattern

the impact of rapid early to mid holocene palaeoenvironmental changes on neolithic settlement at nea nikomideia thessaloniki plain greece the site of nea nikomideia is one of the oldest and most important neolithic settlements in northern greece and the wider balkan peninsula having been first occupied by early farmers at around 6500 cal bc important archaeological excavations conducted in the 1960s suggested that the settlement was located close to an ancient coastline during the neolithic however palaeoenvironmental change and landscape evolution in the vicinity of the site have seldom been considered in detail six cores from the western and central parts of the thessaloniki plain were therefore drilled in 2008 and subjected to palaeoenvironmental analyses including sedimentology laser grain size and magnetic susceptibility measurements chemical analysis loss on ignition and carbonate content stable isotopes analysis coupled with x ray diffraction measurements molluscan faunal analysis and radiocarbon dating the recognition of several important facies representing freshwater lacustrine and fluvial and brackish lagoonal and marine influenced conditions have shed light on the environmental and landscape evolution of the western part of the thessaloniki plain and associated impacts on human occupation during the last 10 000 years the general sequence proved in the cores indicates the predominance of lacustrine conditions during the early holocene with the occurrence of a marine transgression at c 6000 5800 cal b c this major palaeoenvironmental change corresponds with the 8 2 ka event and is a likely cause for the desertion of nea nikomideia at that time subsequent regression of the shoreline to the east saw that the area around nea nikomideia returns to predominantly terrestrial conditions and the deposition of lacustrine and fluvial deposits

vegetation pattern and sedimentation changes in the context of the lateglacial climatic events case study of staroje lake eastern belarus abstract a lake sediment core collected from the staroje lake southeastern belarus reveals significant changes of the terrestrial and limnic environmental during the lateglacial and early holocene in the periglacial zone of the late weichselian glaciation the combination of lithological loss on ignition palaeobotanical pollen non pollen palynomorphs diatoms and isotopic 18o 13c 14c proxy parameters was applied for the reconstruction of the vegetation pattern and sedimentation regime the lateglacial pre interstadial gs 2 vegetation was dominated by mineral soil pioneers with scattered occurrence of pinus and betula an interstadial gi 1 dominated by pinus forest with increasing representation of open ground species since approximately 13 500 cal bp and lateglacial stadial gs 1 with recurring opening of the vegetation pattern with scattered tree patches including those of picea presence of pinus stomata confirms the local origin of this plant since the pre interstadial starting from the holocene birch later accompanied by other deciduous species ulmus alnus quercus corylus took over in the local vegetation structure isotopic records 18o 13c obtained on bulk carbonates as well as diatom data exhibit several shifts reflecting variations both in terrestrial and limnic environment distinct negative excursion of 18o curve recorded during the first half of the gi 1 event suggests intensive groundwater discharge accompanied by active transportation of detrital carbon in to the basin limited basin productivity is also indicated by lithological and diatom records since approximately 13 700 cal bp sedimentation regime in the lake stabilised and productivity of the basin started to increase in positive correlation with loi data a considerable decrease in 18o values punctuated by a rapid jump in the middle of the interval was recorded during the gs 1 stadial and could be associated with the deterioration of the environmental regime and degradation of the soil layer increasing erosion activity alongside the rising input of detrital carbonates into the basin the water table was low as indicated by diatom data recovery of the environmental regime preceded the gs 1 holocene boundary as is seen in lithostratigraphical and isotopic data during the early holocene stable isotopes show several episodes with altered levels suggesting instability of the environmental regime most probably related with the global climatic alterations

oxygen isotopes in meteoric calcite cements as indicators of continental paleoclimate because meteoric water 18 o values decrease with decreasing ambient temperature and increasing latitude 18 o values of meteoric calcite cement should exhibit a similar relation with paleolatitude and be an indicator of continental paleotemperatures to test this we compiled isotopic and paleolatitude data for 20 meteoric cements and nine speleothems ranging in age from devonian to modern and in paleolatitude from 3 5 to 83 mean 18 o values for meteoric cements and speleothems both show the same negative correlation with paleolatitude the 18 o vs latitude trend for these carbonates is almost identical to that predicted for modern inland environments but differs from the trend for coastal environments this suggests that the ground water controlling the ultimate composition of meteoric cement is derived predominantly from inland recharge if it is assumed that the modern meteoric water 18 o vs temperature relation is valid for the past and that insignificant evaporation occurred prior to carbonate precipitation then coastal and inland paleotemperatures can be calculated from the 18 o values of meteoric calcite 18 o mcl and seawater 18 o sw by using the equations t coastal 13 3 32 6 0 231 0 0613 18 o mcl 18 o sw and t inland 17 8 16 2 0 572 0 1233 18 o mcl 18 o sw where t is temperature in c calcite precipitated from coastal meteoric water at temperatures between 0 and 25 c will exhibit a narrow range in 18 o 6 to 4 where 18 o sw 0 the 18 o of calcite precipitated from inland meteoric water will be sensitive to paleotemperature ranging from 14 to 5 where 18 o sw 0 for temperatures of 0 to 25 c

early palaeozoic terranes in new zealand and their relationship to the lachlan fold belt abstract two tectonostratigraphic terranes of palaeozoic age are recognised in the western province of new zealand separated by the north trending anatoki thrust the buller western terrane is composed largely of a relatively uniform suite of quartz rich elastics mainly turbiditic sandstone siltstone and black shale and ranges from basal ordovician to late ordovician in age it is an equivalent of the ballarat bendigo belt of victoria the takaka eastern terrane contains a varied assemblage of middle and late cambrian volcanics volcaniclastics carbonates and turbidites ordovician carbonate shale and sandstone and silurian quartzite the closest equivalent in australia is early palaeozoic rocks of west tasmania the main deformational events in the latest ordovician or silurian buller terrane latest silurian takaka terrane and middle devonian both terranes can be equated with the benambran bowning and tabberabberan orogenies of eastern australia respectively palaeozoic granites are restricted to buller terrane and are spread over a belt 300 450 km wide age range on sparse isotopic data is 370 310 ma late devonian carboniferous with the bulk in the early carboniferous s type granite predominates with several a type granites and a single i type the similarity in the nature and timing of the main events in the sedimentary tectonic and volcanic history of new zealand clearly link it with the lachlan fold belt on the other hand the age and chemistry of the s type new zealand palaeozoic granites make it unlikely that they are the direct equivalents of granite terranes of the lachlan fold belt or antarctica

first evidence for locomotion in the ediacara biota from the 565 ma mistaken point formation newfoundland comment liu et al 2010 1 claim to have found the first evidence for locomotion in the form of putative locomotion traces from the ediacaran 565 ma mistaken point formation of newfoundland if by first they mean the geologically most ancient evidence of animal locomotion they should have discussed

a regional 8200 cal yr bp cooling event in northwest europe induced by final stages of the laurentide ice sheet deglaciation the most notable change in 18o in greenland ice cores during the holocene occurs at 8200 cal yr bp here we present a new high resolution marine record from the northern north sea along with tree ring data from germany which contain evidence of a pronounced temperature drop 2 c contemporaneous with that of the greenland ice core records the synchronous timing of the cooling event in the greenland ice cores marine record and tree ring data from northwest europe reflects a regional influence on the north atlantic ocean atmospheric system suggesting a prominent role of the north atlantic thermohaline circulation the operation of the north atlantic ocean circulation is sensitive to variation in the freshwater budget implying that any change in freshwater flux is capable of altering the north atlantic circulation system we hypothesise minor but long term freshwater fluxes in the final stages of the deglaciation of the laurentide ice sheet as a forcing mechanism 1998 john wiley sons ltd

the early paleozoic development of bioturbation evolutionary and geobiological consequences abstract bioturbation the physical and chemical mixing of sediments by burrowing animals is a critical engineering process in modern seafloor environments and exerts an important control on not only benthic ecology and sediment properties but also ocean wide biogeochemical cycling well mixed sediments have long been assumed to appear at the precambrian cambrian boundary with the first occurrence of the index fossil and three dimensional burrow treptichnus pedum however field based analyses synthesizing ichnological stratigraphic sedimentological and taphonomic data collected from lower paleozoic successions worldwide indicate that sediment mixing in marine shelf environments remained limited until at least the late silurian 120 million years after the precambrian cambrian transition in spite of early advances in complex modes of infaunalization mixed layer development had a much more gradual trajectory and did not occur in step with the first appearance of three dimensional burrows the delayed appearance of modern style intensities of sediment reworking postdating both the cambrian explosion and the great ordovician biodiversification event may be due to the late stage radiation of mobile infaunal deposit feeders biological bulldozers the organisms which are in modern marine settings the most efficient bioturbators the protracted development of the sediment mixed layer holds important implications for contemporaneous biogeochemical cycling and oxygenation of the ocean atmosphere system the delayed development of intensive sediment mixing may have also mediated exceptional preservation of both fossilized soft tissues and shallow tier trace fossils and may therefore have contributed to the anomalous preponderance of konservat lagerstatten and exceptionally preserved shallow tier trace fossils and bioglyphs characteristic of the lower paleozoic stratigraphic record

storm and fair weather wave base a relevant distinction surface waves are an important mechanism for the redistribution of sediment on shallow marine shelves and are commonly interpreted as comprising two distinct populations fairweather waves and storm waves the latter of which are generally thought to penetrate to greater water depths here we used 2 3 10 6 spectral density estimates for the surface ocean collected between 1996 and 2008 from 32 buoys in the caribbean the gulf of mexico and the western atlantic to test the hypothesis that surface waves in the modern ocean comprise two size modes although distinct wave size classes occur in some individual measurements and over the time scales of some individual storms time averaged frequency distributions of wave size are unimodal thus there is no empirical basis for presupposing a distinct bimodal separation in the size of fair weather and storm waves or in the manifestation of such differences in stratigraphic successions instead there is a continuously increasing probability that a wave will reach the bottom with decreasing water depth and a separate probability that describes the hydrodynamic state of the sediment water interface wave size does however exhibit signifi cant geographic bimodality locations in the relatively protected gulf of mexico and caribbean regions have modal wavelengths that are 50 m less than waves at locations along the western atlantic time integrated estimates of the depth of wave penetration provide empirical constraints on the paleo water depths of ancient sedimentary deposits and highlight differences between sheltered shelf environments such as those that characterized many ancient epeiric seas and open ocean facing narrow continental shelves

sm nd isotopic evidence for the provenance of sediments from the adelaide fold belt and southeastern australia with implications for episodic crustal addition abstract in south australia late proterozoic and cambrian sediments were deposited in basins formed within archaean to early mid proterozoic basement these sequences were subsequently deformed and uplifted by the cambro ordovician delamerian orogeny to form the adelaide fold belt in using the adelaide fold belt to address models for lithospheric evolution it is necessary to understand the mechanisms of basin formation and whether the sequences merely reflect reworking of existing cratonic material or if there were new crustal additions this study presents geochemical and isotopic data on the sediments and basement rocks to complement existing data on the delamerian igneous rocks as a means of investigating these questions the data reveal that the archaean mid proterozoic basement rocks of the gawler craton have nd depleted mantle model ages which average about 2 6 ga and nd values at 800 ma in the range 9 to 24 or at 500 ma from 11 to 28 the late proterozoic adelaidean sediments however have an average model age of 1 9 ga and initial nd values in the range 5 to 11 the sequence can be divided into lowermost rift phase sediments derived from erosion of local gawler craton material and a subsequent widely distributed thermal sag phase sedimentation whose isotopic signature is not compatible with the basement this implies that a more primitive or juvenile source was accessed via broadening of the provenance region the cambrian sediments have slightly older model ages 2 1 ga and lower nd 9 to 13 and can be interpreted as mixtures of basement and reworked adelaidean detritus the early palaeozoic sedimentary sequences of the lachlan fold belt to the east have isotopic compositions very like the south australian late proterozoic and cambrian sequences they have an average model age of 1 85 ma but much higher k 2 o na 2 o this indicates that the widespread flysch of eastern australia is the result of recycling of the late proterozoic and cambrian sediments by erosion of the adelaide fold belt with some modification by the mixture of the cambro ordovician mafic and felsic magmatic rocks in this orogen our data suggest regional intracontinental crustal evolution combined with recycling of older crustal material with new additions from the mantle during orogenesis and to a lesser extent episodes of extension and sedimentation

limestone and chert in tectonic blocks from the esk head subterrane south island new zealand the esk head subterrane is a continuous belt generally 10 20 km wide of tectonic melange and broken formation on the south island of new zealand this subterrane separates older and younger parts of the torlesse terrane which is an extensive accretionary prism composed mostly of quartzo feldspathic submarine fan deposits ranging from permian to early cretaceous in age the torlesse is the most pacific ward of several permian and mesozoic accreted terranes in new zealand that record tectonic amalgamation and ultimate accretion against the pacific facing gondwana margin the esk head subterrane of the torlesse is especially informative because it includes within it conspicuous tectonic blocks of submarine basalt and a variety of basalt associated seamount and sea floor limestones and cherty rocks thought to be representative of the subducted plate limestones in tectonic blocks are of late triassic and probably jurassic ages and include 1 submarine cemented pelagic bivalve geopetal packstone grainstone 2 brachiopod bryozoan encrinite and 3 radiolarian pelagic lime mudstone most of the triassic blocks have been dated using conodonts which have remarkably low color alteration index cai values paleogeographic inferences drawn from megafossils bioclasts and radiolarians as well as from carbonate cements indicate deposition of the oceanic sedimentary rocks at paleolatitudes somewhat lower than that of the new zealand part of the gondwana margin but higher than paleoequatorial latitudes these oceanic sediments and their basaltic substrates were evidently emplaced in the torlesse accretionary prism following off scraping from an extensive subducting oceanic plate probably the phoenix plate which was obliquely convergent with the northwest trending gondwana margin during late jurassic and or early cretaceous time

discerning the interactions between environmental parameters reflected in d13c and d18o of recent fluvial tufas lessons from a mediterranean climate region abstract 13 c and 18 o of recent continuous tufa records obtained during a monitoring period spanning 3 to 13 years are compared with the corresponding known environmental conditions three rivers in ne iberia located along a 200 km n s transect are used for this comparison the isotopic variations through space and time are discussed in terms of the environmental and geological parameters that operate on different scales focusing on discerning the interactions between these parameters and providing examples of possible misinterpretation of climatic conditions which is important to past climate studies based on isotopic data the calculation of the actual isotopic fractionation coefficients and the comparison with the literature derived coefficients demonstrates that the studied tufa formation was close to isotopic equilibrium to reflect the water temperature the difference between mean measured water temperature tw and mean calculated tw based on 18 o calcite and measured 18 o water is less than 2 7 c tendencies of these calculated tw are similar to the regional air temperature tair tendencies through time in particular in the case of the 13 year record although certain deviations exist over shorter time spans the best agreement between measured and calculated tw and between 18 o calcite based tw tendencies and tair tendencies corresponds to the tufa stromatolite facies differences between the 18 o calcite records of the three rivers cannot be attributed to temperature changes but to the varying influences of groundwater inputs and isotopic rainfall composition in each river without considering these parameters 18 o calcite based tw calculations yield inaccurate results when comparing the study sites 13 c calcite values do not exhibit distinct patterns over time and 13 c calcite variations are likely caused by local processes that do not reflect general environmental changes these findings underscore the significance of accounting for both groundwater behaviour and rainfall stable isotope composition when interpreting climate parameters in carbonate systems particularly when differences between the isotopic signatures of deposits exist in the same region

microbially induced sedimentary structures in neogene tidal flats from argentina paleoenvironmental stratigraphic and taphonomic implications abstract microbially induced sedimentary structures miss result from the interaction between benthic microorganisms and sediments miss preferably form in upper intertidal to supratidal settings from the archean to the modern the identification of miss in neogene deposits of the rio negro formation late miocene to pliocene rio negro province argentina covering the transition from continental to marine facies and vice versa provides the base to refine the paleoenvironmental interpretation the overall clastic paleocoast was differentiated into high energy erosional domains and protected areas where miss became preserved however during peak transgression also the initially protected areas experienced high energy sediment reworking because of the extent erosion in the high energy coastal setting the localized occurrence of tidal flat deposits was difficult to recognize the thin tidal flat deposits exhibit macroscopic and microscopic features that can be attributed to the interaction between microorganisms and sediment such as cracks with upturned margins sponge pore fabric wrinkle structures multidirected ripple marks floating sand grains and so on in addition the biostabilization processes typical of substrates housing microbial mats led to the excellent preservation of vertebrate footprints that characterize these deposits

stable isotope fossil coleoptera and pollen stratigraphy in late quaternary sediments from ontario and new york state stable oxygen isotope contents of marl deposits and molluscs from lakes and ponds in northern new york state u s a and southwestern ontario canada are remarkably uniform for carbonates formed between about 12 600 yr b p and 2000 yr b p this suggests relatively stable climatic conditions with slowly increasing temperatures throughout this time span an observation already indicated by fossil beetle data and re confirmed by additional data presented in this paper the variations seen in pollen diagrams probably are related to plant colonization and climatic parameters such as changing humidities this contrasts sharply with observations made in europe where variations in pollen diagrams are paralleled by changing 18o contents in lacustrine marls and molluscs which clearly reflect climatic temperature changes during late glacial and early postglacial times 13 500 9000 yr b p 13c contents in marls and molluscs are not directly dependent on climatic change but reflect changing environments with varying aquatic and terrestrial carbon contributions

oxygen isotopes of lake marl at gerzensee and leysin switzerland covering the younger dryas and two minor oscillations and their correlation to the grip ice core the ratio of oxygen isotopes is a temperature proxy both in precipitation and in the calcite of lacustrine sediments the very similar oxygen isotope records from greenland ice cores and european lake sediments during the last glacial termination suggest that the drastic climatic changes occurred quasi simultaneously on an extra regional probably hemispheric scale in order to study temporal relations of the different parameters recorded in lake sediments for example biotic response times to rapid climatic changes a precise chronology is required in unlaminated lake sediments there is not yet available a method to provide a high resolution chronology especially for periods with radiocarbon plateaux alternatively an indirect time scale can be constructed by linking the lake stratigraphy with other well dated climate records new oxygen isotope records from gerzensee and leysin with an estimated sampling resolution of between 15 and 40 years match the greenlandic isotope record in many details under the assumption that the main variations in temperature and thus in oxygen isotopes occurred about simultaneously in greenland and switzerland we have assigned a time scale to the lake sediments of gerzensee and leysin by wiggle matching their stable isotope records with those of greenland ice cores which are among the best dated climatic archives we estimate a precision of 20 to 100 years during the last glacial termination

the calcareous tufa in the tadrart acacus mt sw fezzan libya an early holocene palaeoclimate archive in the central sahara article i nfo the palaeoclimatic signi cance of calcareous tufa deposits found in the presently hyperarid tadrart acacus massif central sahara sw libya is discussed on the basis of u th datings stable isotope analyses and the regional hydrogeological context these deposits formed mostly between c 9600 and 8100 yr bp the isotopic signature 18 o and 13 c of this tufa indicates that the water forming these carbonates originated as isotopically depleted rainwater as a result of the northward expansion of the sw african monsoon system during the early holocene carbonate sedimentation in the tadrart acacus decreased shortly before c 8000 yr bp attributed to a drop in precipitation in the course of the well known 8 2 kyr event a correlation between tufa development and climate change in n and e africa and in the mediterranean basin during the early holocene is discussed the effect of early holocene climate change on both the landscape and the dwellers living in the tadrart acacus region is also evaluated

current tufa sedimentation in a high discharge river a comparison with other synchronous tufa records in the iberian range spain abstract the results from sedimentological isotopic and hydrochemical analyses of current tufa sedimentation conducted in a high discharge river ebron river northeastern spain 1 49 m 3 s through six month monitoring over 3 5 years are discussed in terms of the factors that control local carbonate deposition through space and time and compared with results from other synchronous tufa records in the same climatic domain the findings allow for discerning the influence of the riverbed slope hydrochemistry discharge and groundwater inputs on tufa attributes and assess the significance of tufa as archives of certain climatic events on a regional scale in the ebron river the dominant upstream karstic springs from a jurassic rock aquifer determined the river s hco 3 ca composition two river stretches were differentiated according to localised increments in both pco 2 resulting from additional groundwater inputs and so 4 content influenced by evaporite bearing units the variations in tufa s thickness through space were strongly controlled by co 2 rich springs and local slope variations the monitored sites represent four primary subenvironments with distinct sedimentary facies whose attributes suggest that 1 the tufa deposition rates in each fluvial subenvironment are mainly controlled by the co 2 outgassing intensity linked to local flow conditions and the biological substrate type and 2 stromatolites represent the thickest and most complete record the six month variations in tufa thickness and calculated calcite mass in the ebron river were controlled by temperature dependent physico chemical and biological parameters coupled with high discharge events that provoked tufa erosion the smaller deposition of the ebron river compared to two other synchronous tufa records in the iberian range is linked to 1 the absence of long areas of increased slope 2 the occurrence of significant co 2 rich groundwater springs in the middle reach and 3 the higher discharge and water depth certain high discharge events were recorded as lower deposition rates concurrent in the three rivers moreover anomalous water temperatures calculated from the calcite 18 o in the three rivers for a coincident time span support a regional anomaly in the precipitation 18 o thus the evolution of the short term tufa deposition rates and calcite 18 o composition through time can detect regional climate and hydrology changes and therefore can be robust criteria for correlation in the geological record

pleistocene calcareous tufa from the ellera basin umbria central italy as a key for an integrated paleoenvironmental and tectonic reconstruction abstract continental carbonates calcareous tufa and associated deposits represent a natural archive of paleoenvironmental and tectonic information that can be fully disclosed only by the application of a multidisciplinary approach the aim of this paper is to describe the geological features of the ellera basin umbria central italy by integrating physical stratigraphy sedimentology geochemistry tectonics and biological paleontology palynology data the study of the ellera basin represents a starting point for the improvement of a methodology that could be applied to similar sedimentary systems regardless of their actual location extension and age two stratigraphic units were recognized in the ellera basin both characterized by multiple events of calcareous tufa deposition during the pleistocene in the lower san biagio unit the concurrent finding of hippopotamus h antiquus and leptobos remains associated with late villafranchian molluscs suggests an attribution to the early pleistocene tasso or farneta faunal unit about 1 8 1 5 ma both sedimentological and paleontological data indicate a periodically flooded alluvial plain depositional environment and isotopic values of 13c and 18o register the establishment of a wet paleoclimate the overlying santa sabina unit lies with an angular unconformity on the san biagio unit and was dated to 115 000 8000 years by the application of the u th method the age of the santa sabina unit falls within a period of warm and humid climate mis 5d e and paleoclimatic inferences are supported by the isotopic record 13c and 18o the unit deposited in a well vegetated fluvio lacustrine and fluvio palustrine environment locally dominated by herbaceous taxa as revealed by palynological analysis despite the 1 5 ma time lag between the two units their depositional evolution shared the presence of calcareous tufa whose deposition was controlled by similar paleoenvironmental and paleoclimatic conditions hot and humid interglacial conditions with high rainfalls characterized both periods as well as by the local tectonic setting and activity in both units the maximum thickness abundance of the calcareous tufa occurs at the intersection between two regional tectonic lineaments controlling both the basin subsidence and the ascent of co2 rich water

high potential of calcareous tufas for integrative multidisciplinary studies and prospects for archaeology in europe calcareous tufas are continental carbonates from open air conditions specific to wet and warm periods they contain abundant remains of fauna and flora fossilised in situ and may accumulate regularly over thousands of years offering high stratigraphic resolution for palaeoenvironmental reconstructions as they are mainly comprised of calcite tufas allow direct and precise dating as well as geochemical reconstructions of past climates additionally recent investigations have highlighted their strong potential for archaeology as several studied sequences provided high quality record of in situ prehistoric levels tufas are thus a unique archive in continental areas for development of synergic multidisciplinary investigations of past human societies and associated environmental and climate evolution we emphasise that calcareous tufa are key deposits to investigate human environment climate interactions during interglacial periods from lower palaeolithic to antiquity in europe