penetration of atlantic westerly winds into central and east asia abstract the geographical position of the convergence zone where the western atlantic climate system meets the asian winter monsoonal system depends on their relative strength these individual strengths are determined by the intensities of the air pressure gradients over the north atlantic and the siberian high pressure cell respectively since the factors that forced those gradients varied throughout glacial interglacial cycles the location of the convergence zone should have moved accordingly both the grain size characteristics of wind blown sediments and climate modelling prove that the atlantic influence extended remarkably far eastward at times the northeastern tibetan plateau was at the cross road of western and monsoonal influences during the last glacial this region was dominated by an atlantic signal with millennial scale climatic oscillations that are similar to the north atlantic marine and greenland ice core records in contrast that same region was only under monsoonal influence during the last interglacial it implies that the atlantic winds penetrated more vigorously eastward in full glacial conditions than in interglacial conditions

dating the quaternary progress in luminescence dating of sediments abstract luminescence dating comprises a collection of numerical age techniques that are among the most significant chronological tools currently used in quaternary research this paper briefly reviews the key historical developments in luminescence dating from its roots in thermoluminescence dating of heated minerals to the development of optical dating methods for sunlight exposed sediments we describe the principles and practicalities of the various techniques commonly used in luminescence dating including multiple aliquot single aliquot and single grain procedures and we discuss some of the latest approaches to recognising and minimising potential errors in age estimation e g by means of component analysis and dose distribution methods in optical dating the overview also introduces the other papers in this special issue of quaternary science reviews which address a selection of important issues in basic research technique development and application of luminescence dating to critical questions in the geological and archaeological sciences illustrated with examples from around the world and the last million years of earth history

experiencing new perspectives in the application of reflectance spectroscopy in loess research abstract diffuse reflectance spectroscopy drs parameters such as the redness index and hematite goethite ratios are popular in the study of loess paleosol sequences the suggested parameters however have their limitations only some parts of the whole reflectance spectrum are being used and the spectra of some important components may be excluded from the analysis a mathematical statistical method hierarchical cluster analysis was applied to the loess paleosol succession at mala nad hronom slovak republic in order to characterize the entire reflectance spectrum and to classify sediment groups the sedimentary units were classified into seven different cluster groups such as sediments weak and well developed paleosols the distribution of the spectral features in the reflectance spectra was located by using the key wavelength provided by the wilk s lambda analysis the key minerals which play an important role in the classification were determined by characteristic extrema in the second derivative of reflectance spectra of the seven reference minerals hematite goethite muscovite illite montmorillonite kaolinite and calcite mineral groups influence certain wavelengths within the measured range therefore curve sections modified by individual minerals only in a few cases the mentioned mineral groups refer to characteristics of the formation environment and to climate change during the pleistocene

trace metal contamination in sediments from u k estuaries an empirical evaluation of the role of hydrous iron and manganese oxides abstract concentrations of reducible trace metals available to hydroxylamine hydrochloride acetic acid ha have been determined in sediments from contrasting estuaries around the united kingdom specifically estuaries receiving contemporary anthropogenic inputs from catchments which are urbanized and industrialized to varying degrees clyde dee forth loughor mersey and poole harbour and estuaries receiving inputs from mineralized catchments where working of sulphidic ore deposits was important in the past fal hayle helford and tavy mean estuarine ratios of fe mn ranged from less than 10 dee mersey loughor to about 100 fal poole harbour inter estuarine variations in the mass contributions of fe and mn were attributed to differences in geological and hydrological catchment characteristics while intra estuarine variations were attributed to local differences in hydraulic sorting of sediment and redox conditions the relative contributions of hydrous fe and mn oxides to the accumulation of trace metals cr cu pb zn was evaluated by applying different regression analyses to each estuarine dataset overall the most significant correlations were with fe and in estuaries draining mineralized catchments where well defined contaminant metal sources exist poor correlations in other cases were related to the dissolution of additional metal bearing phases including carbonates by the digest dee loughor or the inability of low energy environments clyde poole harbour to buffer the impacts of local sources of contaminant metals mean estuarine concentrations of pb and zn ranged from about 25 g g 1 poole harbour to 200 g g 1 hayle and 80 g g 1 forth to 1500 g g 1 hayle respectively pooled pb and zn data were defined by a single regression equation which was not controlled by the availability or abundance of oxidic material suggesting common environmental and anthropogenic sources and similar sorptive and post depositional behaviours for these metals pooled cr and cu data however exhibited distinct groupings which were attributed to the differential sources and sorptive behaviours of these metals naturally occurring cr is highly resistant to the ha digest and excess concentrations above a baseline of about 2 5 g g 1 which characterises sediment from mineralized catchments are the result of contamination from contemporary or historical industrial processes e g mean concentrations in the clyde and forth are about 30 g g 1 copper is available to the ha digest in sediments of estuaries draining mineralized catchments where concentrations locally exceed 750 g g 1 but is highly resistant to the ha digest in sediments of industrialized estuaries where concentrations are typically between 5 and 40 g g 1 this is because cu derived from the dissolution of sulphidic minerals adsorbs readily to hydrous fe oxides while cu derived from contemporary industrial and municipal sources appears to interact with anthropogenic organic matter and the resulting complexes partition into sediment organic matter which is relatively resistant to the ha digest although the ha digest cannot readily resolve geochemical and anthropogenic metals in hydrous oxides and other sorbents dissolved by ha the availability of metals like cr and cu may give some indication of the history of the contaminant e g its source and subsequent particle water interaction mechanism more generally from a management and assessment standpoint this approach affords a first order estimate of contaminant metal loading which is geochemically and biologically available

the influence of grain size analysis methods and sediment mixing on curve shapes and textural parameters implications for sediment trend analysis abstract to this day deterministic physical models capable of explaining the evolution of grain size distributions in the course of transport are still lacking for this reason various attributes of particle frequency distributions in particular curve shapes and textural parameters have for many decades been investigated for potential information about transport behaviour and size sorting processes of sediments in numerous environments such approaches are essentially conceptual and hence rely heavily on the validity of the assumptions on which they are based a factor which has to date been largely ignored in this context is the fact that different methods of grain size analysis e g sieving laser absorption and diffraction settling velocity measurements when applied to the same sample material produce variable curve shapes and hence incongruous textural data this is illustrated by selected examples showing the differences between sieving and settling results conversion of settling velocities into equivalent settling diameters psi phi transformations and the influences of particle shape particle density and water temperature it is demonstrated that particle size distributions are not only method dependent but also dependent on the adopted post processing procedure as a result only frequency curves generated by the same method and subsequently processed by identical computational procedures can be meaningfully compared furthermore the computation of textural parameters from bi or multimodal size distributions produces spurious results which are unrelated to the processes leading to the mixing of different size populations frequently observed in nature in such cases only the decomposition of such distributions into individual populations and the spatial comparison of such populations makes any sense because a physical explanation for the generation of size distributions is lacking a particular curve shape of a grain size population has no meaning on its own only a systematic comparison of progressively changing curve shapes and associated textural parameters of sediments collected on a closely spaced grid can yield data suitable for sediment trend analysis

quaternary surface processes indicated by the magnetic fabric of undisturbed reworked and fine layered loess in hungary abstract statistical analytical methods were applied to classify the magnetic fabric of samples from different hungarian loess profiles a previous study of the anisotropy of magnetic susceptibility ams of hungarian loess suggested that typical wind blown or undisturbed and redeposited loess were well differentiated by known statistical methods the analyses of new samples require a review of previous results and the terms like typical wind blown reworked and redeposited loess the type of magnetic fabric of fine layered loess is classified by a new mathematical method in ams study of loess hierarchical cluster analysis the following quaternary surface processes were revealed by characteristics of the magnetic fabric of hungarian loess the primary magnetic fabric preserves the possible transport or accumulation direction of dust direction of maximum susceptibility ne sw axis and the structure of the fabric was affected by compaction in the case of loess the deviation of the inclination from vertical indicates the accumulation of dust on a sloping surface the secondary magnetic fabric fabric of the material after reworking or redeposition of loess shows the magnetic fabric characteristics of reworked or redeposited material scattered values of the principal susceptibilities indicate the effect of bioturbation redeposition fine layered loess samples is indicated by the alignment of the direction of maximum and intermediate susceptibilities on a stereographic plot and the degree of alignment possibly indicates the energy of the surface process lower or higher degree of energy connected to different kind of surface process can produce different kind of magnetic fabric the magnetic mineralogy of the pilot samples is determined by isothermal remanent magnetisation irm measurements no differences between loess samples with different sedimentary structure could be shown the dominant phase in the magnetic fabric that determined the magnetic character of samples was magnetite maghemite

structure and composition of calcified roots and their identification in calcareous soils abstract fine white branching structures isolated from calcareous soils in southern france were shown by microscopy and by chemical and mineralogical analysis to be calcified roots these structures occur mainly in rendzinas calcic xerosols and cambisols that are dense or rich in fines and where drainage is slow visible to the naked eye they can locally represent up to a quarter of the soil mass calcified roots consist of calcite elements whose mean size varies from 60 to 80 m and which retain the structure of the original cells of the root cortex each calcified cell has a central nucleus composed of two crystals on average and is coated with a thin mineral layer that seems to be poorly crystallized some retain organic remnants and the structure of cell walls calcified cells contain tubes less than 1 m in diameter which appear to have formed by weathering although they have generally not been recognized as calcified roots similar microstructures have been indicated in some calcareous soils and calcretes both present day and ancient ones that suggests that calcified roots are widespread and that their occurrence contributes to the genesis of some calcareous soils

calibration of modelled mixing patterns in loess grain size distributions an example from the north eastern margin of the tibetan plateau china genetically meaningful decomposition unmixing of sediment grain size distributions is accomplished with the end member modelling algorithm unmixing of the loess grain size distributions of a late quaternary loess palaeosol succession from the north eastern tibetan plateau indicates that the loess is a mixture of three end members representing very fine sandy coarse silty and medium silty loess the unmixing approach potentially enables the unravelling of sediment fluxes from multiple dust sources opening the way to significant advances in palaeoclimatic reconstructions from loess grain size distribution data however as laser diffraction size analysis is a volume based technique the proportional contributions of the modelled end members might deviate significantly from weight proportions hence calibration of the end member volume proportions to weight proportions must be established before one can calculate the source specific dust fluxes this paper reports the findings of a sediment mixing experiment which enables calibration of the modelled mixing patterns established for the tibetan loess palaeosol succession 2005 international association of sedimentologists

late quaternary paleosols stratigraphy and landscape evolution in the northern pampa argentina the field properties micromorphology grain size geochemistry and optically stimulated luminescence osl ages of two late quaternary sections have been used to reconstruct the sequence of pedosedimentary processes and to provide insights into landscape evolution in part of the northern pampa of argentina paleosols developed in paludal sediments adjacent to the parana river at baradero and in loess at lozada can both be correlated and linked to other sites thus enabling for the first time the tentative recognition and tracing of a diachronous soil stratigraphic unit that probably spans the equivalent of at least part of marine oxygen isotope stage ois 5 the paleosol at lozada was truncated and buried beneath fluvial sediments during the time span of ois 4 and 3 eolian gradually replaced paludal inputs at baradero over this period and there were also two clearly defined breaks in sedimentation and development of paleosols the period corresponding to ois 2 was marked by significant loess accumulation at both sites with accretion continuing into the mid holocene only at lozada the more developed nature of the surface soil at baradero probably reflects a combination of a moister climate and a longer soil forming interval

distribution and normalization of heavy metal concentrations in mangrove and lagoonal sediments from mazatlan harbor se gulf of california concentrations of heavy metals carbonates organic carbon and granulometry were examined in sediments from 60 sites within mazatlan harbor and adjacent areas regional distribution had a strong for al fe li and ni and weak for cd co cr pb v and zn seaward concentration gradient decreasing from the upper lagoon the highest concentrations for most metals occurred in fine grained sediments from infiernillo estuary the upper lagoon and the industrial zone in contrast lower levels were usually found in the sandy sediments of the navigation channel port entrance and an area associated with sewage outfall analysis of transects in mangrove and lagoonal sediments indicated that the amount of fine material and organic carbon increases towards the margins where mangrove sediments exist while metal variations were not clearly observed in most of the metals examined only ni v pb and cu showed a slight tendency to increase towards the margins sometimes lagoonal sediments had redox and texture characteristics comparable to those from mangrove substrate thus competing because of a similar capture capacity of metals metal data were normalized against al and li using a combination of normalization techniques 95 prediction intervals regional anomalies and enrichment factor it was found that al and li were good normalizers for most of the examined metals and they are important constituents of one or more of the major fine grained heavy metal carrier s and adequately reflect the granulometric variability in the sediments of the study area

the soils on the calcareous sand dunes southeast of south australia the properties of soils on previously dated sand dunes from robe to naracoorte in south australia were examined in these areas younger sand dunes are composed of fresh sand but older sand dunes are composed of calcarenited sand the soils on the sand dunes developed successionally by the age of sand dunes the soil properties of these sand dunes differ depending on the ages of the sand dunes the properties of sand particles in soils are as follows

a multi proxy study on polygenetic middle to late pleistocene paleosols in the hevizgyork loess paleosol sequence hungary abstract a multi proxy analysis including grain size magnetic susceptibility and the examination of stable isotopes of hypocoatings was performed on the loess paleosol succession at hevizgyork hungary field investigations suggested a continuous record of sedimentation and pedogenesis however after the identification of the bag tephra it revealed that paleosols and loess units are missing from the section despite no obvious signs of erosion fluctuations in the measured proxies indicate a polygenetic development of the upper paleosol paleogeomorphological processes are supposed to be responsible for the polygenesis of the paleosols alongside of the differences in the paleoenvironment and the local geomorphological position erosional processes could be more intensive during the beginning of interglacials along the slope when vegetation was sparse but precipitation increased on the other hand it is presumed that sedimentation decreased locally during glacial periods because the strong winds carried away the deposited dust these paleoenvironmental features may well have led to the partial erosion of paleosol horizons and the lack of or entire alteration of thin loess formed during the glacials therefore the successive paleosol formed on the previous one the case study shows that although the polygenetic development of paleosols disrupts the clear chronostratigraphical subdivision of the section it can nonetheless provide valuable information about the sequence evolution

effect of mica on particle size analyses using the laser diffraction technique research methods papers abstract new sizing technologies commonly make particle size analyses more routine simpler and less time consuming the proliferation of new technologies led syvitski et al 1991 to recommend that new particle size instruments should no longer have their results compared with those of the classical methods of sieving and pipetting however care is required to ensure that results are broadly comparable to those obtained using established methodologies especially where sediment classification and environmental processes are being interpreted using traditional schemes the progressive development of new classification schemes based on modern particle size analysis techniques will eventually mitigate this problem laser particle size analyses of upper neogene micaceous terrigenous deposits from new zealand have yielded some significantly different grain size distributions compared to traditional sieving methods these differences typically escalated with increasing sand content a series of test samples spiked with increasing amounts of mica demonstrate that very small amounts of mica 2 wt have the potential to significantly alter the grain size characteristics obtained using a laser particle sizer compared to sieve analyses this is probably due to the mica particles having a a higher light scattering property and b large numbers of particles per unit volume resulting in mica being overestimated

visible nir reflectance a new approach on soil evaluation the aim of this work was to develop a spectral reflectance sr based methodology to evaluate soil types and soil tillage systems soil samples located along nine toposequences with basalt and shale were collected in sao paulo state brazil sr of soil samples was measured with a laboratory spectroradiometer between 450 and 2500 nm sr curves were evaluated at different depths to determine soil classes as for conventional methods of soil classification soil survey maps were developed by descriptive interpretation of the spectral curves and statistical analysis as well these maps were compared with detailed and semidetailed soil maps based on chemical physical and mineralogical soil attributes conventional method organic matter total iron silt sand and mineralogy quartz magnetite kaolinite and smectite were the most important attributes influencing reflectance intensity and spectral features and allowed characterization and discrimination of soils strong absorption features centered at 1900 nm were related to oh molecules in free water of 2 1 minerals identification of soil classes was most precise when the entire spectral curve of different depths was analysed simultaneously including features and intensities parent material variation along toposequences and weathering variability modified soil characteristics and its respective sr data the detection of these alterations was essential to determine soil line demarcation soil line demarcation and number of soil classes detected by sr analyses were similar to the detailed soil map determined by conventional methods sr laboratory measurements can be used as a methodology to assist soil surveys spectral data can also group soils under similar tillage systems

small scale secondary caco3 accumulations in selected sections of the european loess belt morphological forms and potential for paleoenvironmental reconstruction eighteen important quaternary loess paleosoil sites have been studied across the european loess belt they included approximately 50 buried soils the over and or underlying loess and the present day surface soils where possible from the numerous types of secondary caco3 accumulations recognized only the small scale accumulations are discussed in this paper including calcified root cells caco3 hypocoatings needle fiber calcite powdery calcite coatings earthworm biospheroliths and calcite pseudomorphs on gypsum most of the features studied are found in the rhizosphere microecosystem each of these features showed a unique relationship with organic matter micro organism and plant distribution moisture and leaching processes for example the exceptional abundance of calcified root cells is an indicator of a long stability of soil surface during favorable climatic conditions needle fiber calcite is related to biomineralization of saprophytes in soils with sufficient moisture and decomposing organic matter the presence of powdery calcite coatings covering clay and mn coatings in non calcareous soils indicates a change from leaching to non leaching soil moisture regimes earthworm biospheroids provide arguments for a relative stability of the soil surface without rapid burial processes or drastic prolonged water stress finally gypsum pseudomorphs are indicators of changes in local climatic parameters in addition to a discussion of the genesis and the dynamics of the various accumulations several examples are given to show how these accumulations can be used as indicators of a changing environment such as renewed loess deposition the extent of drought or varying intensity of leaching during the year to conclude various forms of small scale secondary caco3 accumulations are common in the loess paleosoils and each type has the potential to contribute to a better understanding of the evolution of the paleoenvironment therefore it is proposed that their individual presence or absence throughout the pedostratigraphical levels and throughout the paleo topography should be recorded at all scales of observation

grain size and accumulation rate records from late cenozoic aeolian sequences in northern china implications for variations in the east asian winter monsoon and westerly atmospheric circulation we attempt to reconstruct the history of westerly and monsoonal circulations in northern china using variations in sediment grain size and accumulation rate at four loess sections in the central chinese loess plateau the initiation of aeolian accumulation at about 7 6 ma in the main part of the chinese loess plateau probably marked the onset of the monsoonal circulation both the monsoonal and westerly circulations weakened from 7 6 to 5 2 ma subsequently the monsoonal circulation strengthened progressively from 5 2 ma to the present in addition the westerly circulation strengthened from 5 2 to 0 6 ma but then weakened thereafter and especially during the last 0 6 ma comparison of our aeolian records and the deep sea sediment record suggests that the strengthening trends of the monsoonal and westerly circulations were associated with the progressive development of global ice sheets during the late cenozoic abrupt changes of both the monsoon and westerly circulations occurred at 7 6 3 4 and 1 2 0 9 ma together with a weakening trend of the westerly circulation in the last 0 6 ma and are interpreted as the consequence of the episodic uplift of the tibetan plateau spatial differences in the grain size characteristics amongst the four sections suggest that the circulation intensity and variability decreased from west to east across the loess plateau due to the topographic effect of the tibetan plateau in addition some spatial differences may have been the result of local topographic effects c 2008 elsevier b v all rights reserved

distribution and genesis of calcitic pedofeatures within a rapidly aggrading loess paleosol sequence in china abstract the distribution of calcitic pedofeatures within part of a buried paleosol complex on gaolanshan mountain near lanzhou in the western semi arid part of the loess plateau of china is interpreted in terms of a pedosedimentary model controlled by changes in dominance of regional climatic monsoonal forces during periods of moderate loess accumulation rates and moisture availability accretionary pedogenesis was characterised by localised dissolution and redistribution of calcite and development of compound calcitic depletion concentration pedofeatures these took one of two forms i equigranular hypidiotopic calcitic coatings or infillings 100 350 m and calcitic depletion hypocoatings the reconstruction provides the basis for explaining the ubiquitous occurrence of high concentrations of sand size grains and nodules of calcite within weakly leached horizons of other paleosols in the western part of the loess plateau of china their presence reflects not only the influence of semi arid conditions prevailing during the main stable soil forming intervals but also preceding drier periods of accretionary pedogenesis associated with transitional changes in relative dominance of dry northwesterly winter monsoons responsible for the transport of the dust to that of moist southwesterly and southeasterly monsoons the study emphasises the general need for a pedosedimentary approach when attempting to interpret loess paleosol sequences

sedimentology of seismo turbidites off the cascadia and northern california active tectonic continental margins northwest pacific ocean abstract holocene turbidites from turbidite channel systems along the active tectonic continental margins of the cascadia subduction zone offshore vancouver island to mendocino triple junction and the northern san andreas transform fault the triple junction to san francisco bay have been analyzed for sedimentologic features related to their seismic origin centimeter thick silt sand beds turbidite base capped by mud layers turbidite tail and interbedded with hemipelagic silty clay intervals with high biogenic content have been characterized by visual core descriptions grain size analysis x ray radiographs and physical properties along the northern california margin in upstream single tributary canyons and channels most turbidites are uni pulsed classic fining up whereas downstream below multiple tributary canyon and channel confluences most deposits are stacked turbidites because each set of stacked turbidites has no hemipelagic sediment between each turbidite unit and each unit has a distinct mineralogy from a different tributary canyon we interpret that a stacked turbidite is deposited by several coeval turbidity currents fed by multiple tributary canyons and channels with synchronous triggering from a single san andreas fault earthquake the cascadia margin is characterized by individual multi pulsed turbidites that contain multiple coarse grained sub units without hemipelagic sediment between pulses because the number and character of multiple coarse grained pulses for each correlative multi pulsed turbidite is almost always constant both upstream and downstream in different channel systems for 600 km along the margin we interpret that the earthquake shaking or aftershock signature is usually preserved for the much stronger cascadia 9 mw compared to weaker california 8 mw earthquakes which result in upstream uni pulsed turbidites and downstream stacked turbidites consequently both the strongest 9 mw great earthquakes and downstream confluences cause multi pulsed and stacked turbidites that are typical for seismo turbidites generated by a single great earthquake along both margins earthquake triggering and multi pulsed or stacked turbidites become an alternative explanation for amalgamated turbidite beds in active tectonic margins and show that multiple grain size pulses and reverse grading are not unique criteria for hyperpycnites thalweg levee turbidites or mini basin margin turbidites the analyses of the turbidites along the cascadia and northern california margins reveal common sedimentologic characteristics of turbidites triggered by great earthquakes that can be used to distinguish seismo turbidites in other active tectonic margins around the world

estimating the settling velocity of bioclastic sediment using common grain size analysis techniques most techniques for estimating settling velocities of natural particles have been developed primarily for siliciclastic sediments therefore to understand how these techniques apply to bioclastic environments measured settling velocities ws of bioclastic sedimentary deposits sampled from a nearshore fringing reef in western australia were compared with settling velocities calculated using results from several common grain size analysis techniques sieve laser diffraction and image analysis and established models the effects of sediment density and shape were also examined by using a range of density values and three different models of ws sediment density was found to have a significant effect on calculated ws causing a range in normalized root mean square error of up to 28 depending upon settling velocity model and grain size method accounting for particle shape improved errors in predicted ws by 3 to 6 and removed any velocity dependent bias which is particularly important for the fastest settling fractions when shape was accounted for and measured density was used normalized root mean square errors were 4 10 and 18 for laser diffraction sieve and image analysis respectively the results of this study show that established models of ws that account for particle shape can be used to estimate settling velocity of irregularly shaped sand sized bioclastic sediments from sieve laser diffraction or image analysis derived measures of grain size with a limited amount of error collectively these findings will allow for grain size data measured with different methods to be accurately converted to settling velocity for comparison this will facilitate greater understanding of the hydraulic properties of bioclastic sediment which can help to increase our general knowledge of sediment dynamics in these environments this article is protected by copyright all rights reserved

different paleoenvironments of late pleistocene age identified in verőce outcrop hungary preliminary results abstract complex geomorphological geological paleopedological and chronometrical investigations were started to reveal the development of the alluvial section and the loess paleosol sequence containing remnants of a late palaeolithic site near ver ce hungary different paleoenvironments were identified in the profiles of the abandoned brickyard influenced by different facies in the margin of fluvial alluvial palaeo danube and proluvial southeast pediment of borzsony mountain area and the environments affected by the climate fluctuation of late pleistocene loess paleosol sequence overlying the base of alluvial materials sediments possibly deposited by palaeo danube were identified in a basal section of the abandoned brickyard the alluvial facies was indicated by sand silt and clay layers in the sediment sequence some parts of the alluvial sediments were covered by loess in the glacial periods intercalated by four paleosol horizons formed during interglacial or interstadial periods the sedimentation of loess and the forming of paleosols were finished by pedimentation processes sheet wash redeposition indicated by the fine layered material at the top of each paleosol horizon another complex fluvial alluvial section was identified at a different part of the brickyard possibly developed synchronous with the loess paleosol sequence during the late pleistocene based on relative and chronometrical dating methods e g archaeological stratigraphy and correlation of the artifacts 14c and luminescence dating the development of the loess paleosol sequence started in marine isotope stage 6 mis6 and the youngest layer dated to mis2

age and origin of terra rossa soils in the coonawarra area of south australia abstract the famous terra rossa soil in the coonawarra area south australia is dominated by locally derived aeolian detritus which probably accumulated over the last 120 130 ka four soil profiles and associated limestone and lunette deposits were investigated using the following methods mass balance geochemistry of bulk soil samples major and trace elements quantitative x ray diffraction xrd mineralogy strontium isotopes 87 86 as well as grain size analysis and cation exchange capacity these data show that the terra rossa soil from the coonawarra has a thick clayey b horizon which is geochemically homogeneous and dominated by smectite and kaolinite mass balance calculations show unrealistic weathering scenarios when plotted using silicate residuum from the underlying limestone as parent realistic weathering scenarios are produced with fine grained silicate material from local lunette deposits as parent strontium isotopes of silicate residuum from gambier limestone 0 78 contrast strongly with the clayey b horizon 0 726 strontium isotope ratios of silicate material from a local lunette 0 725 are similar to the b horizon soil values strontium isotope ratios from regional geological units indicate that the strontium signature in the lunette and soil b horizon is dominated by weathering products from the palaeozoic kanmantoo shales extensively exposed upwind to the west on kangaroo island and the fleurieu peninsula optical optically stimulated luminescence osl dating of 61 individual quartz grains single aliquot from three samples in the coonawarra soil profile one from the a horizon and two from the b horizon shows that most of the quartz sand grains have been buried for only a few thousand years many of the grains however have been buried for tens of thousands of years with three grains having exposure ages of between 105 and 109 ka the large population of young exposure dates represents quartz sands recently exposed in the a horizon and which have been translocated down to the b horizon the older exposure dates are interpreted as representing grains that were buried during or soon after the accumulation of wind blown silt and clay our current model concerning the timing and conditions of aeolian deposition of the coonawarra soil is that much of it accumulated during the relatively wet last interglacial period around 120 130 ka during that time span it is thought that the playa lunette systems in the low lying areas to the west were particularly active and generated a significant local dust flux

pedosedimentary division rock magnetism and chronology of the loess palaeosol sequence at roxolany ukraine abstract the loess mantle of the viii dniestre terrace at roxolany in the black sea area of ukraine is subdivided into six units which encompass the following palaeosol taxons pedocomplexes pk with evidence for several soil forming and sedimentary episodes incipient monogenetic palaeosols and horizons of carbonate concretions these cyclical loess palaeosol units provide a depositional record from the end of the matuyama chron through the holocene the detailed pedosedimentary subdivision of loesses at roxolany is generally consistent with magnetic susceptibility depth functions and seems to reflect global climatic variations earlier chronologies guidebook of the international geological congress xxvii session 1984 are re estimated on the basis of a revised position of the matuyama brunhes boundary and by detailed rock magnetic and micromorphological studies the strongly developed chernosem of pk 4 at approximately 22 m depth showing features of rubefication and the highest magnetic susceptibility value is viewed as a good stratigraphic marker of the late cromerian and seems to represent the climatic optimum of the brunhes chron oxygen isotope stage 13 the uppermost pk 2 is represented in the lower part by a chernosem analogous to surface soils of the area and is argued to be no younger than the last interglacial oxygen isotope stage 5e the poor preservation of pk 2 seems to result from processes of soil degradation and deflation at the time of interglacial glacial transition the closely spaced palaeosols between pk 2 and pk 4 seem to relate to three independent interglacials highest resolution of the palaeoclimatic record is found at the final matuyama chron from pk 9 to pk 8 and in incipient soils that contain either humic horizons with enhanced magnetic susceptibility or only horizons of large carbonate concretions

characteristics of pleistocene climate cycles identified in cerna valley loess paleosol section vertesacsa hungary abstract a climate cycle model was calculated using different methods e g paleomagnetic sedimentological and heavy mineral studies on the loess sequence containing four paleosol and five loess layers in cerna valley the model is based on the development of the sediment sequence created by the influence of the climatic geological and geomorphological phenomena and contains the following cycles the homogeneous non laminated loess was developed during the semiarid 350 400 mm y and cold periods in the pleistocene the magnetic fabric was built up by multidomain ferromagnetic minerals and reflects the direction of dust deposition or and the paleoslope the accumulation period of dust was followed by a more humid 650 mm y pedogenic period indicated by the enrichment of superparamagnetic minerals and by the disturbed or inverse magnetic fabric developed during pedogenesis by different processes e g leaching bioturbation the third period following the pedogenic period is a humid erosional phase indicated by the fine layered reworked loess the magnetic fabric built up by multidomain ferro and superparamagnetic minerals was characterized by better aligned directions of principal susceptibilities than in the wind blown material sheet wash and other water logged surface processes appeared in the fabric of these layers this process is possibly connected to non periodic sudden events with high precipitation and absence of the vegetation the next cycle started with the following dust accumulation period

on the reliability and comparability of laser diffraction grain size measurements of paleosols in loess records abstract laser diffraction grain size data and size distributions of paleosols are widely used in paleoenvironmental reconstructions as physicochemical alteration related proxies of past changes of the sedimentary environment different laser diffraction devices optical theories and optical settings are being applied nowadays and ignorance of several uncertainty factors and drawbacks of this indirect grain size characterization approach has led to poorly comparable and reproducible granulometric datasets here we present a detailed comparison of grain size results acquired by three state of the art widely used laser diffraction devices fritsch analysette 22 microtec plus horiba partica la 950 v2 and malvern mastersizer 3000 grain size distributions were calculated using both the fraunhofer and mie scattering theories and a wide variety of optical settings 68 different complex refractive indices 1 45 1 6 0 01i 1i for 10 samples from loess paleosol sequences of the carpathian basin our findings demonstrate that optical settings have significant effects on grain size distributions especially for the finest fractions clay and fine silt populations interestingly the selection of laser diffraction devices was an even more deterministic factor in grain size characterization as revealed by network analyses clustering of bulk and size fractionated grain size records was primarily determined by the device used and also by the applied optical settings at the same time the real physical differences of samples were found to be deterministic exclusively for the sand sized fraction as such these findings emphasize the importance of the accurate description of applied methodological details in research papers as comparability and reproducibility of granulometric datasets cannot be ensured with a lack of information about instrumental conditions and settings

multiple environmental change at the time of the modern human passage through the middle east first results from geoarcheological investigations on upper pleistocene sediments in the wadi sabra jordan upper pleistocene sediments at wadi sabra ma an district jordan were geoarcheologically investigated from 2008 2010 the wadi sabra valley system situated east of the dead sea rift and south of the ancient nabataean capital of petra has preserved sedimentary deposits which are connected with several upper paleolithic sites first results from sedimentological and geochemical analysis supported by archeological and radiometric dating provide evidence of fluvial and fluvio eolian sedimentation during marine isotope stage mis 3 and 2 from at least 38 ka to 18 ka followed by at least one erosional event that finally determined the recent valley morphology several calcretes buried surfaces and initial soil horizons indicate phases of landscape stability and potentially moister climatic conditions than today inferred favorable environment of the time allowed for human occupation of the wadi sabra attested throughout the cultural stages of the initial early and evolved upper paleolithic and the early epipaleolithic thus illustrating the occurrence of homo sapiens in the near east field work at wadi sabra is expected to further elucidate the out of africa ii movement of our species leading modern humans to europe possibly via the middle east and the balkan peninsula both regions now under comparative investigation by the cologne aachen b1 project group of the crc 806

heterogeneity in homogeneous brabantian loess during the late pleniglacial abstract the brabantian loess is often seen as a homogeneous sediment package deposited under cold and dry climatic conditions haesaerts et al 1981 however in 1981 two small tundra gleysols were discovered in the brabantian loess haesaerts et al 1981 to unravel other possible changes in the sedimentary system during deposition a more detailed look at the homogeneous brabantian loess is carried out the loess transporting process is reconstructed based on the combination of both grain size and grain shape parameters these parameters are defined with automated dynamic image analysis and statistically compared with the two dimensional kolmogorov smirnov test as suggested by vandenberghe et al 1998 our gleysols are generally correlated to a period of reduced grain size most likely the more subtle the gleysols the weaker the link between their formation and grain size reduction mazzullo et al 1992 already stated that aeolian transport was very selective regarding grain size and sorting capacities our research points toward an extremely selective aeolian transport regarding the shape of the grains therefore combining both particle size and particle shape can be very useful when reconstructing aeolian transport processes this combination can also discriminate samples with a different transport and sedimentation history

paleoenvironmental reconstruction based on the morphology and distribution of secondary carbonates of the loess paleosol sequence at suttő hungary abstract micro and macroscale secondary carbonates were investigated from the loess paleosol sequence of sutt hungary as secondary carbonates are formed in pedosedimentary environments they designate how the microecosystem adapts to dust accretion besides pedogenic aspects the hints of diagenesis can be tracked especially concerning leaching effects the main goal of this study was to make an attempt whether the distribution related signals of secondary carbonates combined with their genetic properties can be used for paleoenvironmental reconstruction the elaborated method is wet sieving of bulk loess paleosol samples in order to 1 separate secondary carbonates to describe morphological properties partly with the help of scanning electron microscopy and 2 provide a depth related semiquantitative distribution the semiquantitative distribution is ordered to the marine isotope stage units of the sutt sequence mis 6 to 2 the mis 6 section is characterized by presumably slower dust accumulation and raises the possibility of a multiphase leaching history throughout the profile lower dust accumulation rates with increasing aridity are assumed upwards in mis 5 mis 4 is typified by arid conditions and the alternation of lower and higher dust accumulations certain properties of paleosol development and frost deformation related to secondary carbonates can be distinguished in mis 3 dust accumulation rates are presumed to be consistent upwards in this section during mis 2 different sedimentation stages are distinguished but generally they show a decreasing trend upwards to the modern soil this work serves as a complementary method which may help to refine the paleoenviromental signals of the sutt loess paleosol sequence to determine relative sedimentary phases the limitations of the method have to be taken into consideration as the results are semiquantitative

expanding the proxy toolkit to help identify past events lessons from the 2004 indian ocean tsunami and the 2009 south pacific tsunami article i nfo some of the proxies used to identify palaeotsunamis are reviewed in light of new findings following the 2004 indian ocean tsunami and the 2009 south pacific tsunami and a revised toolkit provided the new application of anisotropy of magnetic susceptibility ams to the study of tsunami deposits and its usefulness to determine the hydrodynamic conditions during the emplacement of tsunami sequences together with data from grain size analysis are presented the value of chemical proxies as indicators of saltwater inundation associated marine shell and or coral high energy depositional environment and possible contamination is demonstrated and issues of preservation addressed we also provide new findings from detailed studies of heavy minerals new information gathered during the unesco international oceanographic commission ioc international tsunami survey of fine onshore sediments following the 2009 south pacific tsunami is presented and includes grain size chemical diatom and foraminifera data the tsunami deposit varied ranging from fining upward sand layers to thin sand layers overlain by a thick layer of organic debris and or a mud cap grain size characteristics chemical data and microfossil assemblages provide evidence for marine inundation from near shore and changes in flow dynamics during the tsunami

aeolian silt transport processes as fingerprinted by dynamic image analysis of the grain size and shape characteristics of chinese loess and red clay deposits abstract this study applied dynamic image analysis dia sympatec qicpic to characterize the grain size and shape of chinese aeolian sediments in order to fingerprint their transportation processes this is the first time this technique has been applied to late neogene and quaternary silt particles 2 63 m from the chinese loess plateau clp we selected four well studied quaternary loess palaeosol sequences along a north south transect across the clp and compared their grain size distribution obtained by dia with that yielded by laser diffraction particle size analysis ld fritsch analysette 22 and sympatec helos kr this comparison demonstrated that dia is successfully able to differentiate loess units from palaeosols and to characterize clearly spatiotemporal variations in the grain size records of loess palaeosol sequences formed during the last two glacial and interglacial periods this is consistent with grain size results obtained using ld dia is also able to characterize spatial variations in the more fine grained aeolian red clay deposits underlying the quaternary loess and allows the quantification of the fluvial contribution to red clay sequences dia of the characteristics of grain shapes in loess palaeosol sequences and red clay deposits revealed a systematic pattern whereby the aspect ratio decreased with increasing grain size indicating that systematic shape sorting occurred during the aeolian transportation of these dust particles it could be inferred from our study that particles in a certain grain size range correspond to a specific aspect ratio range and may in turn be aerodynamically distinguishable from each other and further correlated with the wind velocity strength also evident from analysis of our dia data was a subtle but systematic downwind decrease in the aspect ratio of the particles in the loess units this observation suggests that elongated and or flat particles with a low aspect ratio were transported further downwind than more symmetrically shaped particles with a high aspect ratio this study indicates that dia of grain size and shape characteristics can be an additional powerful tool for identifying grain size and shape sorting trends determining the dominant mode of transport and reconstructing transport pathways of silt sized aeolian sediments

needle fiber calcite a critical review and a proposed classification abstract from a review of the recent literature and our own observations the different morphologies of needle fiber calcite are classified they can be characterized as monocrystalline rods with or without serrated edges or as polycrystalline chains the simplest monocrystalline habit of needle fiber calcite is the individual micro rod m larger monocrystalline rods ma exist in multiples of two more complex forms are found as paired monocrystalline rods with serrated plates along their length mb this group includes three habits which can be distinguished by the number of plates and their orientation relative to the rod finally there is a monocrystalline form mab intermediate between the categories ma and mb which shows the transition from the simple coupled rods to rods with errated plates although polycrystalline needles p have rarely been reported in the literature three types of morphologies have been identified each type of crystal has a specific origin the m micro rods are physicochemical nuclei or calcified bacteria they do not seem to evolve towards larger or more complex morphologies the ma rods are related to biomineralization inside the fungal sheaths the mb rods postdate liberation of ma rods from mycelian bundles the serrated plates are secondary syntactic crystallizations of physicochemical origin whose growth can be inhibited for various reasons the origin of p chains is less well understood but they seem to be physicochemical crystallizations related to evaporation and desiccation therefore these three groups m ma mb and p have similar morphologies but do not seem to be related genetically the only known link is between the ma and mb rods there is no evolutionary s quence of needle fiber calcite habits but a convergence of forms between crystals whose origins are different and independent structures described in the literature as convoluted random cutane and nest like are the result of either evolution of the mycelian bundles or movement of material and organisms in the soil in the case of m micro rods the microfabric is related to the random precipitation around nuclei in pores filled with a highly supersaturated solution initially the p chains also precipitate without preferential organization and later on the growth seems to preferentially constitute chains although the mechanisms are still not understood moreover needle fiber calcites do not indicate a particular climatic environment

contrasting the geochemistry of oxic sediments across ecosystems a synthesis abstract the geochemistry of oxic sediments was contrasted across a range of canadian aquatic ecosystems 7 freshwater lakes 3 circumneutral and 4 acidic 15 peatlands 5 mineral rich 5 moderately poor and 5 mineral poor 9 wetlands 3 oligosaline 3 mesosaline and 3 euryhaline an estuary deposited and suspended sediments and an intertidal region sediments were characterized by a simultaneous extraction that separated sediments into easily reducible er metal oxyhydroxides of mn and easily reducible amorphous oxyhydroxides of fe and reducible r metal more crystalline forms of oxyhydroxides of fe organic matter and the concentrations and partitioning of zn cu and cd associated with these 3 sediment components ecosystems were distinct with respect to er fe and organic matter canonical variate analysis cva with 53 of among system variation in geochemistry attributed to these 2 components sediments of peatlands and wetlands contained greater amounts of organic matter whereas sediments of lakes intertidal and estuarine deposited and suspended sediments were characterized by greater amounts of er fe a further 21 of among system variation could be ascribed to organically bound fe that was greater in acidic lakes and mineral rich peatlands as compared to other systems concentration and partitioning of cd within sediments was regionally dependent with 41 of among system variation cva attributed to differences in er cd and r cd cadmium from peatlands and lakes located in ontario was recovered from all 3 sediment components whereas sediment from wetlands the estuary and the intertidal regions of british columbia bc contained no organically bound cd with amounts recovered occurring mostly as er cd lakes and peatlands located in ontario contained 3 5 fold total cd as compared to ecosystems located in bc a further 21 of among ecosystem variation was attributed to zn partitioning zinc in peatland and wetland sediments occurred as r zn as compared to lake and estuarine deposited sediments where zn was recovered both as er and r zn total zn was also 3 5 fold greater in sediments of systems in ontario as compared to those sampled in bc concentration and partitioning of cu was similar across all systems with cu recovered from the organic component of sediment the geochemistry of surficial oxic sediments with respect to er mn r fe and organic matter and the geochemical associations among these sediment components is ecosystem and region dependent for assessing impacts of metals on sediment dwelling biota the geochemical characteristics of the system under study should first be defined

effect of mica on particle size analyses using the laser diffraction technique new sizing technologies commonly make particle size analyses more routine simpler and less time consuming the proliferation of new technologies led syvitski et al 1991 to recommend that new particle size instruments should no longer have their results compared with those of the classical methods of sieving and pipetting however care is required to ensure that results are broadly comparable to those obtained using established methodologies especially where sediment classification and environmental processes are being interpreted using traditional schemes the progressive development of new classification schemes based on modern particle size analysis techniques will eventually mitigate this problem laser particle size analyses of upper neogene micaceous terrigenous deposits from new zealand have yielded some significantly different grain size distributions compared to traditional sieving methods these differences typically escalated with increasing sand content a series of test samples spiked with increasing amounts of mica demonstrate that very small amounts of mica 2 wt have the potential to significantly alter the grain size characteristics obtained using a laser particle sizer compared to sieve analyses this is probably due to the mica particles having a a higher light scattering property and b large numbers of particles per unit volume resulting in mica being overestimated

the south east karst province of south australia the south east karst province of south australia is an extensive area of low relief with dolines cenotes uvalas and a variety of cave types developed in the soft porous flat lying tertiary gambier limestone and also as syngenetic karst in the overlying calcarenite dunes of the pleistocene bridgewater formation the most spectacular surface karst features are the large collapse dolines especially those that extend below the water table to form cenotes shallow swampy hollows occur in superficial quaternary sediments these are an enigmatic feature of the bool region where all gradations appear to occur between definite karst dolines and nonkarstic hollows some depressions may be polygenetic involving a combination of 1 primary depositional hollows on coastal flats or in dune fields 2 deflation and 3 karst solution and subsidence there are extensive underwater cave systems in the southern part of the province and the bulk of the cave development there may well lie below the present water table although these systems would have been at least partly drained during the lower sea levels of the last glacial period systematic variations within the province reflect differences in the parent rock types the extent and nature of the cover and most importantly the hydrology in particular the depth to the water table and its gradient

particle size measurement of diatoms with inference of their properties comparison of three techniques abstract diatom rich sediments are common in several oceanic regions especially the southern ocean some of these are strongly affected by bottom currents and are expected to be sorted by the flow examination of data on diatoms response by instruments commonly used for size measurement is presented here diatoms are silt to fine sand size filigree silica structures of many shapes with high porosity thus both the bulk density and shape strongly influence the size that is calculated from measurements we document the particle size of diatoms measured by instruments based on settling velocity sedigraph electrical resistance pulse counting coulter counter and laser diffraction malvern laser sizer the malvern laser consistently measures the largest diameters followed by the coulter counter and then settling based techniques relationships between these inferred sizes all expressed as quartz equivalent spherical diameters have implications for the physical properties of diatom tests earlier work has demonstrated that laser diffraction responds to the particles external projected area the effects of both low effective density and irregular shape of diatoms compared with terrigenous grains on their settling velocity causes the sedigraph to indicate relatively small diameters shape effects are less pronounced for quasi spherical diatom species the coulter counter records the diatoms solid volume and is relatively unaffected by their density or shape the measurement of different physical parameters by these instruments offers a basis for estimation of diatom porosity fluid occupied volume within the test measurements of the external diameter and solid volume allow estimates of porosity for laser sizes 20 m this is 75 95 which can be quite well modeled as a perforated spherical shell of wall thickness 1 1 5 m for paleocurrent interpretations a settling based technique makes sedigraph measurements of particle size the most useful but the visual size is best given by laser

subglacial till formation microscale processes within the subglacial shear zone abstract this was a study of subglacial deformation till genesis from a modern temperate glacier at skalafellsjokull iceland detailed microscale properties of till samples from scanning electron microscope sem and thin section analysis were examined from a glacial site with in situ subglacial process monitoring and an exposed subglacial surface in the foreland two lithofacies were examined a grey sandy till derived from the ash and basalt and a silty reddish brown till derived from oxidized paleosols and or tephra layers these also represented a clay content continuum from low 0 3 to high 22 3 the evolution from debris to subglacial till was investigated this included a reduction in grain size 21 for grey lithology 13 reddish brown lithology and reduction in rounding ra 32 for the grey lithology 26 for the reddish brown lithology and the quantification and analysis of the different grain erosion comminution processes in the resultant till it was shown that the microstructures within a till were dependent on shear strain and glaciological conditions deformation history the low clay content tills were dominated by linear structures lineations and boudins and anisotropic microfabric whilst the higher clay content tills were dominated by rotational structures turbates and plaster and isotropic microfabric these results are important in our understanding of the formation of both modern and quaternary tills and informs our reconstruction of past glacial dynamics

luminescence dating of the stratzing loess profile austria testing the potential of an elevated temperature post ir irsl protocol abstract feldspar infrared stimulated luminescence irsl signals saturate at 2000 gy i e 500 700 ka assuming a dose rate of 3 4 gy ka typical for loess and it is therefore theoretically possible to date middle pleistocene loess however the accuracy of age estimates is hampered by anomalous fading which leads to significant age underestimation fading corrections have been proposed but these corrections are reliant on inherent assumptions and in any case are inapplicable at large doses as the growth curve approaches saturation recent studies have identified a post ir irsl signal that shows less fading and is thus less dependent on accurate fading corrections this study builds upon these investigations and applies a post ir irsl sar dating protocol to polymineral fine grain samples of the loess palaeosol sequence in stratzing lower austria after a preheat at 320 c 60 s and an ir bleach at 50 c 200 s irsl was measured at 290 c for 200 s the same set of conditions were used to measure the response to a test dose recycling ratios recuperation and dose recovery tests show that this protocol is suitable for the loess under investigation although finite residual doses of up to 20 gy are observed for the oldest samples the natural signal is in or close to saturation indicating that fading is negligible in nature this observation is inconsistent with the measured laboratory fading rates of 1 1 5 decade and needs further investigation

subglacial comminution in the deforming bed inferences from sem analysis this study investigates the variations in erosional processes beneath briksdalsbreen a norwegian valley glacier with a thin coarse grained deforming bed the subglacial zone was investigated in situ close to the central glacial flow line site a and close to the valley wall site b via boreholes the till was collected using two different sediment samplers and the bed was examined using a borehole video camera in order to evaluate how representative borehole sampling was of the subglacial environment the results from in situ subglacial samples were compared with random samples taken from an exposed subglacial surface in the glacier foreland as well as a sample taken from the site after glacier retreat the results indicated that the texture of the exposed subglacial surface was similar to in situ samples from subglacial site b close to the valley wall and that the samples collected with the small sediment sampler had the closest fit sem analysis revealed eroded quartz grains at both sites as a result of rotation abrasion and fracture the samples from close to the valley wall were very poorly sorted with evidence for rounding and preservation of pre weathered surfaces which suggest that a relatively simple pattern of erosion from crushing to rotation dominated however the till from the centre of the glacier was better sorted more angular and with few pre weathered surfaces we suggest that this results from a more complex glacial erosional history associated with greater strain and longer residence time within the deforming layer when compared with other deformation tills it was confirmed that there is a relationship between grain size and erosional style clay rich tills show little comminution fine sand rich tills generate a significant silt component whilst the coarse sand rich tills at briksdalsbreen showed complex deformational styles but no significant silt component

multi proxy lake sediment record of prehistoric paleoindian archaic archaeological paleoenvironments at rice lake ontario canada abstract the arrival of paleoindian peoples in the lower great lakes ca 11 5 ka cal bp coincided with a phase of lowstand lakes and rapid environmental change in southern ontario at rice lake an archaeologically rich area north of lake ontario rising early holocene water levels inundated wetland areas exploited by paleoindian and archaic peoples in order to better understand the distribution of submerged archaeological sites and the water level history of rice lake a detailed multi proxy study was conducted on two vibracores extracted from the open lake and a shallow the basin stratigraphy consisted of holocene organic rich muds gyttja laminated marls and peats overlying glacial lake iroquois sands and clay deposits two erosional hiatuses indicating lowstand phases eh 1 ca 12 5 11 ka cal bp eh 2 ca 6 3 ka cal bp were identified by rapid shifts in particle size and thecamoebian abundance and assemblages the dominant thecamoebian species in the open lake basin were arcella vulgaris and centropyxis constricta aerophila indicating the trophic status of the lake has remained stable throughout the holocene in the mcintyre lagoon the eh 1 lowstand was associated with a unique bog and wetland species bullinularia and phryganella sp along with the recovery of microdebitage indicating that paleoindian peoples were likely exploiting wetland resources such as plants fish and waterfowl we show that the study of lacustrine paleoenvironments using a multi proxy approach provides additional information for identifying areas of archaeological potential and gaining additional understanding of settlement patterns and resource procurement strategies of paleoindian and archaic peoples in southern ontario

revisiting the chronostratigraphy of late pleistocene loess paleosol sequences in southwestern ukraine osl dating of kurortne section abstract due to the general lack of other high resolution paleoclimate records loess paleosol sequences are crucial archives for disentangling past climate variability in southeastern europe here we present results of a multi proxy sedimentological and geochemical investigation of kurortne loess paleosol section from southwestern ukraine coupled with detailed optically stimulated luminescence osl dating osl investigations were carried out on quartz grains of different grain sizes 4 11 m 63 90 m and 90 125 m using the single aliquot regenerative sar protocol the osl dating results are in line with previous findings on dating loess paleosol sequences along the black sea shore in romania as well as worldwide i ages obtained on different grain sizes are in agreement for equivalent doses of less than 200 gy whereas for higher equivalent doses 4 11 m ages underestimate the coarser fraction ages and ii an inverse correlation between dated grain size fractions and saturation characteristics is reported our combined dating and sedimentological approach would confirm that the investigated uppermost 4 5 m at kurortne cover the last glacial cycle adding important data in better constraining local and regional chronostratigraphic correlations the application of the sar protocol on 63 90 m quartz grains on samples collected from the lower part of s1 soil the kaydaky unit and from the kaydaky pryluky units boundary produced ages of 123 10 ka and 85 6 ka respectively as the temporal range covered by these units in the ukrainian quaternary stratigraphic framework is still debatable our results confirm the broad correlation of the kaydaky pryluky paleosol units at kurortne with the last interglacial i e mis 5 dating the uday and bug loess units produced ages corresponding to mis 4 and mis 2 respectively whereas the sample collected from the vytachiv unit provided an age of 37 7 2 4 ka assigning this paleosol to mis 3 on the basis of trends in the magnetic enhancement the onset of pedogenetic processes likely commenced already around 20 ka but the formation of the topmost s0 soil has begun after 13 8 1 0 ka

delineating stratigraphic breaks at the bases of postglacial eolian dunes in central alberta canada using a portable osl reader temporal constraints for the late pleistocene deposition of eolian dunes that occur in central and northern alberta canada can be provided by dating sediments from the dune bases using luminescence techniques in places however the postglacial dunes overlie glaciofluvial sands that resemble the eolian deposits in texture such that demarcating the bases of the dunes is often problematic in this study we address the problem by employing a portable optically stimulated luminescence osl reader to construct luminescence profiles that depict luminescence signal variation with depth with the portable osl reader measurement can be performed on bulk sediments negating the need for laborious separation procedures to isolate pure mineral fractions as is required in regular luminescence dating measurements can also be carried out in the field permitting quicker decision making during sample collection results from this study presented as depth variations of feldspar derived infrared stimulated luminescence irsl signals and predominantly quartz generated post ir blue osl signals show that luminescence profiling enables one to distinguish between eolian deposits that make up the dunes from the underlying non eolian sands the identification of such cryptostratigraphic interfaces is made possible by differences in the dosimetric histories of the sediments the delineation of the dune bases allows targeted sampling that yields best luminescence age approximations for the initiation of postglacial eolian deposition in the region luminescence profiling of eolian sequences would also in theory permit the identification of depositional breaks of extended duration copyright 2012 john wiley sons ltd

integrating sieving and laser data to obtain bulk grain size distributions abstract it is not always possible to use a single technique to determine the complete grain size distribution of a natural sediment namely when dealing with successions of variable grain size or with sediments or soils that contain silt clay and sand gravel populations in this work we assess the feasibility of using laser diffraction to measure sand size particles by analyzing the representativeness of laser samples and quantifying the deviations between results of sieving and laser diffraction four groups of sediments with different grain size distributions and proportion of heavy minerals were compared it is demonstrated that the risk of laser sample underrepresentativeness is higher when measuring grains coarser than 1 mm in particular when clay silt particles are also frequent depending on the size fraction the divergence between the results of sieving and laser diffraction due to shape and density effects is variable and not easy to predict quantitatively given these uncertainties it is proposed to use different computational threshold diameters that separate the fractions considered by sieving and laser diffraction and measure part of the distribution with both techniques we developed a flexible computer application that allows users to visually compare different possibilities of combined laser sieving grain size distribution curves and to choose the best option of threshold diameter the best combined results can then be used to model the grain size distribution

particle size separation and evidence for pedogenesis in samples from the chinese loess plateau spanning the past 22 m y a comparison between particle size distributions determined by laser diffraction and the pipette method confi rms previous studies that point to a variable underestimate of the clay fraction using laser diffraction relative to the values obtained by pipette analysis in order to yield four particle sized fractions 8 m for further analysis the pipette method was used on loess and paleosol samples from sites on the chinese loess plateau spanning the past 22 m y in all cases a subsidiary mode in the 8 m fraction provides a basis for evaluating the relative contributions of pedogenic and detrital components pretreatment using acetic rather than hydrochloric acid for carbonate removal results in no signifi cant loss of ferrimagnetic minerals and allows magnetic characterization of the separate fractions this confi rms the isolation of almost all the fi nest pedogenic ferrimagnetic grains in the clay fraction and their negligible contribution to the magnetic properties of the coarse fractions in all the samples from early miocene time onward because similar conclusions may be drawn from previous studies of late pleistocene samples from the east central and extreme western parts of the chinese loess plateau we conclude that this approach provides a basis for separately characterizing eolian deposition and pedogenesis throughout the region and for the whole time span of loess accumulation

evaluation of a wide range laser diffraction grain size analyser for use with sediments the qualities of a laser diffraction grain size analyser the coulter ls 100 range claimed by the manufacturer 0 4 900 mum in a single measurement are evaluated on sediments of fluvial and lacustrine origin accuracy and resolution of measurement on standard latex spheres are excellent reproducibility of the results on natural sediments appears to be satisfactory but the method underestimates the fraction of clay particles with an efficiency of detection 36 70 proportional to the clay content determined from pipette analysis this efficiency is somewhat higher than those reported from other instruments of the same generation comparison of the coulter ls 100 with other sizing techniques shows good agreement with the sieving method but some differences appear with the electroresistance particle technique median and mean size values measured by the coulter counter ta1 are systematically lower than those obtained by the coulter ls 100 analyses show good correlation with those of a malvern laser particle analyser but a discrepancy appears with very fine silt and clay sized sediments the coulter ls 100 detects a higher clay content than that measured with the malvern laser sizer 2600 except when precise measurements of clay content are needed the coulter ls 100 produces precise and accurate results in size ranges required for geological and environmental studies

the influence of paleogeomorphology on the stable isotope signals of paleosols abstract the stable carbon and oxygen isotope composition of three different local variations of the same mis5e paleosol horizon were studied in the ver ce loess paleosol sequence hungary these variations developed in local top paleoslope and paleovalley topographic positions with characteristic secondary carbonate features such as hypocoatings hcs based on the 13c 18o enrichment or depletion of the secondary carbonate samples the so called stable isotope matrix sim was established and this was used to characterize stable isotope signals as potential paleoenvironmental indicators to complete the sim box and whiskers plot analysis of 13c and 18o values were elaborated on the pedogenic horizons of the paleosol variations the joint application of the sim and the box and whiskers plot analysis revealed the way in which the climatic stable isotope signal of hcs can be overwritten by the various topographic positions of the hosting paleosols the local top paleosol variation will necessarily have developed under climatic influence the expected transition from cold to warm phases as loess deposition characterized by upbuilding pedogenesis was followed by more effective soil development due to the takeover of topdown pedogenesis was characterized by increasingly negative stable isotope values in the upward succession of genetic horizons in the sequence the same transition was identified by different stable isotope patterns in the case of the other two paleosol variations the paleovalley position implies hydromorphic effects and significant evapotranspiration under denser vegetation cover the paleoslope position was affected by abrupt environmental changes such as run off processes triggered by higher precipitation leading to continuous disturbance in the course of the development of the sequence

the difference of two laser diffraction patterns as an indicator for post depositional grain size reduction in loess paleosol sequences abstract chemical and physical processes within aeolian sediments result in a reduction of the particle grain size in loess sediments the post depositional grain size variation is due to a reduction of the dominating coarse silt fraction in favor of the clay and fine silt fraction generally there are two post depositional fractionation processes 1 the chemical weathering of silt sized minerals like mica and feldspar as a result of hydration and hydrolysis 2 the physical weathering of all minerals contained in the primary loess sample by cryogenic and fluvial relocation processes there are many widely used proxies to estimate their vertical variation in thick sediment columns however there are complicating factors related to aeolian sorting effects the distance to the source regions and carbonate dynamics which reduces the sensitivity of common proxies to the chemical weathering in this study we present a simple and quick method using laser diffraction calculations of grain size distribution obtained by two optical models the fraunhofer approximation and the lorenz mie theory to highlight the enrichment of fine grained material by post depositional chemical weathering processes in contrast to the fraunhofer approximation the lorenz mie theory considers the complex refractive index which depends on the mineral properties thus the difference of the grain size distributions gsd calculated with both models is sensitive to the mineral composition of the sample in separated submicron mineral suspensions we found that different crystalline properties are reflected by repeatable signatures of the gsd this specific gsd signature also occurs in the submicron grain size range of bulk measurements of weathered loess samples in contrast to previous studies we obtain reliable laser diffraction results in the submicron range summarizing we present the gsd within the submicron range of bulk measurements as a suitable indicator for the chemical weathering degree of loess paleosol sequences which is virtually unaffected by cryogenic processes weak relocation of inherited weathering products and synsedimentary processes sheet wash saltation or enhanced background sedimentation

micromorphological fabrics and developmental stages of carbonate nodular forms related to soil characteristics abstract carbonate nodules often constitute the first stage of calcrete formation micromorphological analysis of carbonate nodules and nodular fabrics in different soil materials shows that their development is a function of several factors nature of the host matrix texture porosity carbonate and non carbonate clay distribution bulk density and the interactions among them different micromorphological stages therefore exist in different soil materials in calcareous medium textured soil materials the stages of nodule formation are related to the increase of the density of the nodule caused by the accumulation of microcalcites in such a soil material the following stages occur 1 microcalcites within the low to moderate density matrix 2 microcalcites of moderate to high density and moderately dense diffuse nodules parallel calcans may occur 3 microcalcites of high density with dense microcalcitic nodules during these stages the amount of non carbonate clay decreases but is homogeneously dispersed and disseminated with the microcalcites in general the size of microcalcites 1 8 m is inversely related to the clay content in non calcareous medium to fine textured soil materials secondary carbonate precipitates in intrapedal and or interpedal voids as large sparry crystals due to pedoturbation processes the nodules thus formed are subjected to recrystallization resulting in a microsparry pattern the development stages are 1 few calcans and crystal chambers 2 crystic nodules mainly of sparry crystals and an increase of calcans and crystic chambers 3 recrystallized nodules composed mainly of microspars in coarse grained materials secondary carbonates precipitate directly in voids as sparry crystals and the resulting nodules are of the crystic type the large crystals are often subjected to recrystallization in partly calcareous coarse grained materials with additions of calcareous dust particular micromorphological carbonate forms occur in the c horizon cutanic calciasepic fabric forms besides zones of crystic fabric which gradually become calciasepic in the b horizon and include the typical nodular forms of the calcareous medium textured soil material together with appreciable amounts of glaebular halos the processes leading to the formation of these stages occur essentially without a significant biogenic influence where carbonate segregation occurs as rhizomorphs surrounding active roots the fabric is always micritic even in coarse textural soil material

comparison of laser grain size analysis with pipette and sieve analysis a solution for the underestimation of the clay fraction classically the grain size of soil and sediment samples is determined by the sieve method for the coarse fractions and by the pipette method based on the stokes sedimentation rates for the fine fractions results from the two methods are compared with results from laser diffraction size analysis which is based on the forward scattering of monochromatic coherent light from a point of view of laboratory efficiency the laser sizing technique is far superior accuracy and reproducibility are shown by measurements on certified materials it appears that laser grain size measurements of certified materials correspond very well with the certificated measurements tests were also done on a set of randomly selected sediments of fluvial aeolian and lacustrine origin except for the 2 m clay fraction there is a coarsening of the mean diameter of one to two size classes 0 25 caused by the non sphericity of the particles the platy form of the clay particles induces considerable differences eight size classes between pipette and laser measurements the 2 m grain size defined by the pipette method corresponds with a grain size of 8 m defined by the laser particle sizer for the studied sediments using a higher grain size level for the clay fraction when laser analysis is applied enables workers in the geological and environmental field to compare classical pipette analysis with a laser sizing technique

a comparison of grain size analysis methods for sand dominated fluvial sediments abstract grain size distribution is a fundamental tool for interpreting sedimentary unitswithin depositional systems the techniques assessed in this study arecommonly used to determine grain size distributions for sand dominatedsediments however the degree of consistency and differences ininterpretation when using a combination of grain size methods have not yetbeen assessed systematically for sand dominated uvial sediments resultsobtained from laser diffraction x ray attenuation and scanning electronmicroscopy grain size analysis techniques were compared with those obtainedfrom the traditional sieve hydrometer method scanning electron microscopywas shown to provide an inaccurate quantitative analysis of grain sizedistributions because of dif culties in obtaining representative samples forexamination the x ray attenuation method is unsuitable for sand dominatedsediments because of its upper size range of only 300 lm the consistentlystrong correlation between the laser diffraction results and the sieve hydrometer results shows that these methods are comparable for sand dominated uvial sediments provided that sample preparation is consistent the latter two methods can be used together within a study of such sedimentswhile maintaining a high degree of accuracy these results indicate that datafor sand dominated uvial sediments gained from the long established sieve hydrometer method can be compared with con dence to those obtained bymodern studies using laser diffraction techniques keywords hydrometer laser diffraction scanning electron microscopy sieve x ray attenuation introductiongrain size distribution gsd analysis is a funda mental tool in sedimentology and uvial geo morphology it is particularly important indetermining environments of deposition andaspects of the ow regime at the time of deposi tion several methods of gsd analysis are pres ently available this study aimed at assessing thecomparability of sieve hydrometer x ray attenu ation scanning electron microscopy sem andlaser diffraction techniques for quantifying grain size distribution for sand dominated uvialsediments and the inconsistencies in interpreta tion that might occur when using a combinationof these methods such inconsistencies mayoccur when gsd data from contemporary studiesutilizing modern techniques such as laser dif fraction and x ray attenuation are compared withgsd data from prior studies gained by the use oflong established methods such as sieve hydro meter methods the wentworth 1922 scale is the most widelyused scale for sand dominated sediments colby 1964 smith 1970 schumm 1977 folk 1980 miall 2006 understanding the gsd of a depositsedimentology 2008 55 1905 1913

earthworms produce granules of intricately zoned calcite earthworms of the family lumbricidae which includes many common species produce and secrete up to millimeter sized calcite granules and the intricate fine scale zoning of their constituent crystals is unique for a biomineral granule calcite is produced by crystallization of amorphous calcium carbonate acc that initially precipitates within the earthworm calciferous glands then forms protogranules by accretion on quartz grain cores crystallization of acc is mediated by migrating fluid films and is largely complete within 24 h of acc production and before granules leave the earthworm variations in the density of defects formed as a byproduct of trace element incorporation during calcite crystal growth have generated zoning that can be resolved by cathodoluminescence imaging at ultraviolet to blue wavelengths and using the novel technique of scanning electron microscope charge contrast imaging mapping of calcite crystal orientations by electron backscatter diffraction reveals an approximate radial fabric to the granules that reflects crystal growth from internal nucleation sites toward their margins the survival within granules of acc inclusions for months after they enter soils indicates that they crystallize only within the earthworm and in the presence of fluids containing biochemical catalysts the earthworm probably promotes crystallization of acc in order to prevent remobilization of the calcium carbonate by dissolution calcite granules vividly illustrate the role of transient precursors in biomineralization but the underlying question of why earthworms produce granules in volumes sufficient to have a measurable impact on soil carbon cycling remains to be answered

micromorphology of loess paleosol sequences a record of paleoenvironmental change abstract the record of paleoenvironmental change retained within thin sections from loess paleosol sequences is discussed with reference to case studies from western europe china and northwestern usa the paleoenvironmental significance of individual micromorphological features such as calcitic concentrations clay coatings and cryogenic structures are first evaluated and the value of recognising and interpreting microstratigraphic relationships of features in terms of paleoenvironmental change is illustrated recent developments have seen a greater emphasis on using micromorphology within a pedosedimentary approach whereby both pedogenic and sedimentary processes are taken into account when interpreting loess paleosol sequences this has led not only to the acquisition of important information on conditions during phases of enhanced loess accretion and periods of climatic transition but also to an increased awareness of spatial changes in processes and environmental controls during particular time periods micromorphologically based reconstructions have enabled the isolation of key stages of pedosedimentary development although absolute dating of stages is often limited by lack of age controls a novel approach aimed at addressing this limitation afforded by presence of datable tephra in microstratigraphic association with key micromorphological features is discussed

laser diffraction analysis of the disintegration of aeolian sedimentary aggregates in water abstract a new method for the analysis of aggregate disintegration in water was tested using aeolian sediment samples the response of aeolian sedimentary aggregates to wetting and mechanical energy has important implications for the immobilization of aeolian sediments by rainfall and their susceptibility to post depositional erosion by water repeated laser diffraction analysis of a single sample circulating in deionized water provides a detailed view of the changes in particle size distribution as aggregates disintegrate this methodology also allows experiments on the effects of water chemistry exchangeable cation chemistry and prewetting results presented here suggest that aggregates of widely varying stabilities can occur in a wide range of particle size classes that is aggregate stability may to some extent be independent of the hierarchy of aggregate sizes emphasized in earlier research the methods described here are broadly applicable to a variety of soils and sediments but experiments are needed to relate the results more specifically to aggregate behavior under field conditions

particle size distribution analysis of sand sized particles by laser diffraction an experimental investigation of instrument sensitivity and the effects of particle shape laser diffraction is now widely used for particle size distribution analysis of sediments and soils the technique can be very precise and offers advantages of speed and cost over many other methods when used to analyse mixtures of sand silt and clay this study presents the results of an experimental investigation that examined the sensitivity of the beckman coulter ls230 instrument to mixtures of different grain populations and differences in particle shape the instrument was found to have high sensitivity to coarse particles in a finer matrix detection threshold 1 2 but much lower sensitivity to finer particles in a coarser mixture detection threshold 12 17 experiments using near spherical ballotini showed that laser analysis provides very similar values to dry sieving for the mean median and mode but for a range of natural sand samples values for the mean median and mode were offset by 8 21 with an average of ca 15 compared with sieving analysis using a beckman coulter rapidvue instrument which provides both size and shape information provided support for the hypothesis that the differences between laser analysis and sieving are partly attributable to the effects of particle shape however an additional factor is the way in which the laser software interprets the optical diffraction data the software predicts a high degree of log normality in the size distribution such that highly skewed truncated or bimodal samples are poorly represented experiments using sieved fractions of ballotini indicated that even with near perfectly spherical particles the particle size distribution predicted by the laser software includes a relatively large percentage of particles outside the sieve class limits

englacial and subglacial water flow at skalafellsjokull iceland derived from ground penetrating radar in situ glacsweb probe and borehole water level measurements we reconstruct englacial and subglacial drainage at skalafellsjokull iceland using ground penetrating radar gpr common offset surveys borehole studies and glacsweb probe data we find that englacial water is not stored within the glacier water content 0 0 3 instead the glacier is mostly impermeable and meltwater is able to pass quickly through the main body of the glacier via crevasses and moulins once at the glacier bed water is stored within a thin 1 m layer of debris rich basal ice 2 water content and the till the hydraulic potential mapped across the survey area indicates that when water pressures are high most of the year water flows parallel to the margin and emerges 3 km down glacier at an outlet tongue gpr data indicates that these flow pathways may have formed a series of braided channels we show that this glacier has a very low water storage capacity but an efficient englacial drainage network for transferring water to the glacier bed and therefore it has the potential to respond rapidly to changes in melt water inputs

investigating the penultimate and last glacial cycles of the suttő loess section hungary using luminescence dating high resolution grain size and magnetic susceptibility data the loess paleosol record at sutt provides an excellent high resolution archive of climate and environmental changes loess deposits with a thickness of 20 m cover the travertine at sutt in the northern part of hungary next to the right bank of the danube river the loess sequence is intercalated with two greyish stratified horizons three brownish steppe like soils and a pedocomplex including a reddish brown paleosol covered by a chernozem like paleosol detailed infrared stimulated luminescence irsl dating was carried out revealing more or less continuous sedimentation from marine isotope stage mis 6 mis 2 sedimentological and paleomagnetic investigations have been performed to provide a high resolution study of the sutt loess paleosol sequence in order to reconstruct the paleoclimate and environmental changes during the penultimate and last glacial cycles grain size and magnetic susceptibility ms records of the sutt profile basically show similar patterns to those of other european loess sections however small differences are traced at sutt including more intensive deposition of coarser grained materials during mis 6 4 the loess record at sutt has a transitional position within the european loess belt as its sediment was deposited under an intermediate climate between the loess successions from the southern carpathian basin which accumulated under drier climate and the loess sequences from western europe which developed under wetter climate during the middle and late pleniglacial

revisiting the loess palaeosol sequence in paks hungary a post ir irsl based chronology for the young loess series in hungary many loess palaeosol sequences have been found to be discontinuous in order to allow for correlations with other quaternary records reliable chronologies are needed we therefore apply post ir infrared ir stimulated luminescence post ir irsl pirir290 dating to the uppermost 20 m of the loess sequence at paks the pirir290 ages are compared with blue quartz osl ages to test for potential age overestimation due to poor signal re setting and the observed good agreement is taken to imply that the more difficult to bleach pirir290 signal was reset prior to deposition our pirir290 based chronology reveals that most of the late pleistocene loess was deposited during marine isotope stage mis 3 and during the last glacial maximum lgm this is in disagreement with formerly published ages the discrepancy can most likely be explained by anomalous fading resulting in an age underestimate this conclusion is supported by our uncorrected standard irsl ages we further confirm that the basaharc double soil complex can be correlated with mis 7 the underlying loess and soils cannot be dated accurately because the pirir290 signal approaches saturation

seasonal and spatial variations in the source and transport of sinking particles in the strait of georgia british columbia canada three sequential sediment traps were deployed at 150 m in the strait of georgia from march 1996 to february 1998 one at the southern end of the strait one located centrally opposite the main channel of the fraser river and one to the north of the fraser river channels subsequently all three traps were moored at the central site on a single mooring 150 225 and 300 m from february 1998 to january 1999 the highest total flux in the b500 am fraction 2 2 g cm 2 a 1 was recorded at the southern station and the lowest at the northern station 0 044 g cm 2 a 1 an annual flux peak at all three stations coincided approximately with the fraser river freshet may june and the southern station exhibited a second flux peak in september which seemed not to be directly associated with the river s discharge lithogenic particles dominated the flux at all three stations representing about 85 of the total flux at the southern and central stations and 60 at the northern station although that proportion varied widely throughout the year at all three stations according to stable isotope composition y 13 c and y 15 n the majority of the biogenic material was marine derived particularly at the northern station approximately 80 of organic matter marine derived with much of the variation in the trap samples explained by variation in the proportions of marine and terrigenous organic matter however a second source of variation was evident in the isotopic composition of the marine derived organic matter probably because of seasonal changes in nutrient availability productivity and the length of the local food chain as a result the sinking organic matter in the strait of georgia can be described as a mixture of three end members terrigenous marine bloom and marine non bloom the flux and compositional data together with data from sediment cores collected at the same locations imply that most of the particles settle in the southern strait where they may then be transported northward along the bottom toward the central and northern stations d 2005 elsevier b v all rights reserved

influence of parent material and grain size on carbonate coatings in gravelly soils palo duro wash new mexico abstract close examination of carbonate coatings found on the bottoms of pebbles from gravelly soils indicates that soil hydraulic conductivity and respiration rate have a strong influence on the carbonate morphology of aridic soils clast size and lithology strongly correlate with coating thickness because of the nature of unsaturated flow within macropores of gravelly soils thicker coatings are found at the bottom of larger clasts coatings are thickest on limestone pebbles that commonly display dissolution features at their tops model values for soil co 2 based on gas diffusion predict soil atmospheric condition where soil water can remain undersaturated with respect to calcite and dissolve calcareous pebbles throughout the depth of the soil profile this coupled with soil hydrology creates a microenvironmental condition where the largest limestone clasts have the thickest coating a second phenomenon that is apparent from close observation of coatings is that soils containing abundant fines and translocated dust in the matrix have continuous coatings continuous coatings are absent however in soils that do not neighbor a dust source or do not have sufficient fines in the matrix in these soils coatings are almost completely absent from sand and granule size particles suggesting that zones of preferential flow in the soil inhibit carbonate precipitation in parts of the soil profile these inconstancies in the continuity and thickness of coatings suggest that stage iii morphology may not develop at the same rate even locally

sarga fold lősz losz short historical overview of loess research and lithostratigraphy in hungary abstract the over 150 years of hungarian loess research can be divided into three main phases 1 the first phase is the early times of the hungarian loess research from the 1850s until the beginning of the 20th century this was the time of recognition definition of loess and the birth of the first ideas about the origin of loess following the international scientific trends however independent ideas were developed in hungary inspired by the main trends one of the most complex ideas was koch s loess sea idea which describes the origin and deposition of the material of loess from the denudation processes to glaciers fluvial transport and the accumulation of the fine grained material in a giant freshwater lake located in the middle of the carpathian basin 2 the second phase the golden age of loess research is separated into two periods the first period was the investigation and classification of the material of loess e g studies of source area of loess finishing with the definition of the paleosols and their connection to the polyglacial interpretation of the ice age from the start of the 20th century until the 1930s the first and detailed lithostratigraphical subdivision of hungarian loess was in the spotlight of the second period of the second phase the aim of the studies was the correlation of the layers of some key sections and the glacial and interglacial phase of the pleistocene e g correlation of different proxies with the astrocyclostratigraphical milankovic curve or later with the oxygen isotope curves 3 nowadays some studies try to advance a deeper understanding the complex mechanism working in the glacial stadial interglacial interstadial or transition periods of the pleistocene recent studies are part of the beginning of the third phase

sedimentary aggregates in the peoria loess of nebraska usa loess grain size data used to infer transport direction or wind strength are generally derived from vigorously disaggregated samples however these data may not adequately represent the effective particle size distribution during loess transport if the transported dust contained aggregates of finegrained material thin sections of minimally altered c and bc horizons in the late pleistocene peoria loess of nebraska usa indicate the presence of aggregates with diameters of 30 1000 am the larger aggregates 250 am are unlikely to have been transported and are interpreted as the result of soil faunal activity and other pedogenic processes after deposition aggregates smaller than 250 am could have a similar origin but laser diffraction particle size analysis suggests that many are sedimentary particles comparison of minimally and fully dispersed particle size distributions from each sampling site was used to estimate the modal diameter of aggregates the aggregate modal diameter becomes finer with decreasing loess thickness representing increasing distance from the source a similar trend was observed in the modal diameter of fully dispersed particle size distributions which represents the mode of sand and silt transported as individual grains we interpret both trends as the result of sorting during transport supporting the interpretation that many of the aggregates were transported rather than formed in place aggregate content appears to increase with distance from the source explaining a much more rapid downwind increase in clay content than would be expected if clay were transported as particles smaller than 2 am diameter although the peoria loess of nebraska contains sedimentary aggregates many of the coarse silt and sand grains in

reactive iron in marine sediments abstract a combined field laboratory study has been undertaken to explore the mineralogy concentrations and reactivity towards sulfide of iron in marine sediments also considered is the importance of bacterial fe liberation in regulating pore water chemistry two contrasting marine environments are included one is the relatively fe poor foam site and the other is the fe rich sediment of the subaqueous mississippi delta results show that oxide minerals are the most important fe phases in early diagenetic pyrite formation however viewed separately lepidocrocite and ferrihydrite are more reactive towards sulfide than goethite and hematite when fe oxides are present in relatively high concentrations dissolved sulfide is nearly absent from sediment pore waters with concomitant high concentrations of dissolved fe even in the presence of active sulfide production by sulfate reduction a combination of experimental results and diagenetic modelling shows that in some sediments pore water fe finds it origin in the bacterial reduction of iron oxides this seems the case even though greater amounts of fe are reduced by reaction of sulfide with iron oxides it appears that distinct microenvironments may exist in marine sediments where in one microenvironment sulfide reacts with fe oxides locally precipitating fe sulfide minerals in another fe reduced and solubilized by microorganisms migrates freely into solution

luminescence and amino acid racemization chronology of the loess paleosol sequence at suttő hungary abstract the loess paleosol sequences in hungary provide an excellent upper pleistocene climate archive of the carpathian basin loess deposits up to 20 m thick cover the sutt travertine complex located in the very northern part of hungary next to the right bank of the danube river the loess is intercalated with two weakly developed greyish horizons two thinner brownish steppe like soils and a pedocomplex including a reddish brown clay enriched horizon covered by a chernozem like paleosol infrared optically stimulated luminescence irsl dating was applied on polymineral fine grain material to determine the depositional age of the loess the uppermost loess yields irsl age estimates ranging from 15 to 40 ka the loess on top of the pedocomplex yields irsl age estimates ranging from 48 to 60 ka the pedocomplex most likely correlates with the marine oxygen isotope stage mis 5 interglacial period the loess from below the pedocomplex was deposited during the penultimate glaciation as evidenced by amino acid racemization aar results further independent age control is provided by radiocarbon dating for the upper part of the profile and by uranium series 230th 234u ages correlating the travertine below the loess with mis 7 8 the magnetic susceptibility record through the sequence shows a strong correlation with the loess layers and soil horizons

use of anisotropy of magnetic susceptibility ams in the study of tsunami deposits application to the 2004 deposits on the eastern coast of banda aceh north sumatra indonesia abstract we studied emplacement dynamics of the december 26 2004 tsunami deposits in artificial shallow ponds and in shallow lagoons along the northern coast of sumatra in banda aceh area successive tsunami waves inundated topographic lows which acted as sediment traps and favored preservation of deposits individual waves led to the deposition of fining upwards sedimentary sequences this multiple normal grading deposit with a thickness ranging from 2 to 80 cm constitutes a site of major interest for the study of the deposits emplaced by a tsunami wave train the main interest lies in the characteristics of the deposits that can be correlated to the behavior of the waves attested by numerous testimonies in this setting we aimed at testing the applicability of the ams anisotropy of magnetic susceptibility technique as a proxy of unconsolidated sediment fabric the combination of this proxy and traditional sedimentary analysis helped reconstructing the hydrodynamic conditions particularly the flow direction prevailing during sedimentation we applied the ams technique on eight sections stretching inland from 1 5 km to 2 2 km from the pre tsunami coastline grain size and ams data from these deposits provide similar and partially complementary information traction dominates in the basal parts of the deposits and occurs mainly for the basal layers of the sequences whereas settling dominates for the upper layers of these sequences the vertical evolution of the ams parameters within the deposits is related to the arrival of the successive waves with variations in the traction and decantation processes during deposition variations of current strength during sedimentation are related to the wave s momentum and to the progressive infill of topographic depressions the vertical change of the fifth coarsest percentile vs the median grain sizes of the deposits suggests strong variations of the energy of the currents and confirms the evolution of the ams parameters in the present study the fabric of the deposits which developed exclusively during the uprush phase of the cycle also allows the reconstruction of flood directions that are both normal and parallel to the shoreline with variations related to flow dynamics mean grain size and local topographic control due to the absence of backwash in between the waves and low velocity of the final backwash information about the sedimentation conditions of the tsunami deposits appears to be better preserved in topographic depressions in areas located remote from the seashore the ams proxy appears to be a promising tool for further studies of recent and paleo tsunami deposits

stable isotope composition of the carbonate concretion in loess and climate change carbonate concretions are commonly found in the loess in china oxygen and carbon isotopic compositions of carbonate concretions collected from 14 different paleosols s1 s14 in the lishi formation of luochuan loess section china were analysed the isotopic compositions of concretion in loess are useful tools in paleoclimatic study usually the more developed the paleosol is the less negative the 18o values and the more negative the 13c values are the oxygen isotopic composition of these paleosols varies within a range of about 1 3 the carbon isotopic composition however shows larger variations from one paleosol to the other within a range of 5 3 an attempt was made to semi quantitatively estimate the paleosol formation temperature and precipitation based on the carbon and oxygen isotopic data obtained

the biogenic origin of needle fibre calcite needle fibre calcite is one of the most ubiquitous habits of calcite in vadose environments caves deposits soil pores etc its origin either through inorganic indirect or direct biological processes has long been debated in this study investigations at 11 sites in europe africa and central america support arguments for its biogenic origin the wide range of needle morphologies is the result of a gradual evolution of the simplest type a rod this rod is the elementary brick which by aggregation and welding builds more complex needles the absence of cross welded needles implies that they are welded in a mould or under a longitudinal and unidirectional constraint before being released inside the soil pores the difference between the lengthening of the needles and the c axis can be explained by the existence of needles observed under a scanning electron microscope in organic sleeves which can act as a mould during rod growth complex morphologies with epitaxial outgrowths on straight rods cannot have grown entirely inside organic microtubes they must result from soil diagenesis after the release of straight rods in a soil free medium whisker crystals are interpreted as the result of growth and coalescence of euhedral crystals on a rod rhomb chains are considered to be the consequence of successive epitaxial growth steps on a needle during variations in growth conditions isotopic signatures for needle fibre calcite vary from 16 63 to 1 10 and from 8 63 to 2 25 for 13c and 18o respectively the absence of high 18o values for needle fibre calcite precludes a purely physicochemical origin evaporative for this particular habit of calcite as epitaxial growth cannot precipitate in the same conditions as initial needles needle fibre calcite stable isotopic signatures should be used with caution as a proxy for palaeoenvironmental reconstructions in addition it is suggested that the term needle fibre calcite should be kept for the original biogenic form the other habit should be referred to as epitaxial forms of needle fibre calcite

particle size evidence of estuary evolution a rapid and diagnostic tool for determining the nature of recent saltmarsh accretion abstract a conceptual model of saltmarsh sedimentation based on high resolution particle size analysis has been tested on short cores c 0 5 m of known age from the dee estuary nw england uk here two components of the particle size distribution psd are interpreted as the traction load deposited by the faster tidal flow velocities fast tide and the suspension load that settles during the turn of the tide slow tide the feasibility of this model for diagnosing the driving mechanism of estuary evolution in both time and space is tested with reference to historical evidence of saltmarsh accretion up core trends in dated saltmarsh cores and the psds of present day saltmarsh surface sediments cores that show an up core progression from very fine skewed to near symmetrical psds are interpreted in the context of estuary infilling due to a positive sediment budget sediment surplus whilst those that show a persistence of near symmetrical very poorly sorted mesokurtic particle size distributions in the fine to very fine silts size range are considered to be the result of slow tide sedimentation the influences of the two end member styles of saltmarsh accretion i e i infilling due to sediment surplus and ii slow tide settling linked to sea level exhibit spatial and temporal trends as predicted particularly in cores from mid and lower saltmarsh locations the upper saltmarsh cores also show evidence of estuary infilling due to slow tide sedimentation at rates in excess of sea level rise the results confirm that the diagnostic approach can be applied as a pre filtering method for assessing the suitability of saltmarsh sediments for reconstructing sea level trends and for providing input data for improved estuary morphological modelling

the significance of diagenesis versus riverine input in contributing to the sediment geochemical matrix of iron and manganese in an intertidal region summer porewater and spring and summer surficial sediment samples were collected from 26 locations in the intertidal region of the fraser river estuary porewaters were analysed for dissolved iron and manganese as defined by species 50 m concentrations of organic matter declined from the mouth to the foreslope of the estuary with the exception of red fe temporal variation may vs july was insignificant p 0 05 three way anova concentrations of red fe recovered from the surficial sediments were in general greater in the summer vs spring months although spring and summer values were highly correlated pearson product moment correlation coefficient ppcc r 0 89 p 0 0001 as the bioavailability of metals is dependent on sediment geochemistry availability throughout the intertidal region will also be spatially dependent this heterogeneity needs to be taken into account in studies addressing the impact of metals on estuarine systems