the formation of loess deposits in the tashkent region and parts of central asia and problems with irrigation hydrocollapse and soil erosion abstract there are large problems of irrigation hydrocollapse and soil erosion associated with the loess deposits of central asia to get to grips with these we need a clear view of the nature and formation of the loess and in this region there are still disputes and disagreements and controversies important events in the loess deposit formation process can be identified and studied and relative significances assigned there are large loess deposits in the vicinity of tashkent in the north east of uzbekistan these were mapped and studied for many years by g a mavlyanov and associates they used a terminology which appears to be based on pavlov s nineteenth century usage and developed a polygenetic formation theory for loess deposits this was a formation theory very much associated with central asia and essentially favouring a proluvial mechanism a speculative look at the deposits near tashkent allows alternative terminologies and formation mechanisms to be considered in particular the widespread soviet antipathy to aeolian deposition can be examined the deposits associated with the chirchik river upstream of tashkent might be affected by the pavlov mechanisms but could be topped by aeolian deposits the collapse of loess when wetted is controlled by the nature of the ground and is a very significant interaction of soil and water in particular in central asia hydrocollapse and water erosion are closely related and are controlled by the complex nature of loess ground dust clouds in eastern uzbekistan are largely loess related but in the west dust material is raised from the drying aral sea bed this is often clay mineral agglomerate material and can carry dangerous pollutants

desert loess versus glacial loess quartz silt formation source areas and sediment pathways in the formation of loess deposits abstract pathways are presented which show the proposed sequence of events involved in the formation of loess deposits both hypothetical deposits and those of central china hungary nigeria and tunisia these pathways illustrate the potential role of and inter relationships between a variety of silt generating mechanisms in the formation of loess using these pathways the existence of desert loess is discussed and it is concluded that this depends on how the terms glacial loess and desert loess are applied if desert loess is taken either to signify nonglacial mechanisms of silt production or to characterise the environment from which aeolian entrainment took place then desert loess is a very real and widely distributed deposit however if the term glacial loess is used to refer to the global climatic regime under which the loess deposit has formed rather than the geomorphic mechanisms responsible for silt generation then desert loess would not be an appropriate term for the classification of loess deposits it is suggested that classifying loess deposits with reference to the global climatic regime under which they accumulated would facilitate a greater understanding of the role of environmental conditions at all stages in the formation of loess deposits

rivers and loess the significance of long river transportation in the complex event sequence approach to loess deposit formation abstract rivers are essential for loess deposit formation river systems which relate directly to loess deposit formation include the danube and the rhine the mississippi and the missouri the thames and the medway the indus ganges and brahmaputra the dnepr don and volga the clutha mataura and rakaia new zealand rivers the yellow river rivers in south america siberian rivers flowing north the odra and the wisla between the mountains and the ice the syr darya and amu darya into the desert the contention is that rivers are not just important in major loess deposit formation they are mandatory necessary imperative obligatory essential indispensable requisite for a complete and satisfactory study of a loess deposit we need to know how the material is produced how it is transported and distributed across the landscape how intermediate deposits are formed how transportation provides the defining properties i e open structure collapsibility draping across the landscape and what may happen post deposition e g chernozemisation fragipan formation increased collapsibility etc if rivers are essential then it would appear that the british loess is probably alpine material delivered by the proto rhine and the polish loess is not derived from the ice sheet to the north but from the mountains to the south the lack of loess in canada is explained by the absence of suitable rivers the loess in russia and neighbouring countries can be classified as jefferson et al jefferson i f evstatiev d karastenev d mavlyanova n g smalley i j 2003b the engineering geology of loess and loess like deposits a commentary on the russian literature engineering geology 68 333 351 suggested on the basis of associated rivers a new deposit of glacial loess is recognised associated with the dnepr don and volga rivers the uswr loess the smalley leach smalley i j leach j a 1978 the origin and distribution of the loess in the danube basin and associated regions of east central europe a review sedimentary geology 21 1 26 available from www geo edu ro sgr mod downloads pdf smalley sedgeo 1978 pdf vision of the loess in the danube basin and east central europe is probably misconceived they assigned a great significance to glacial action and put loess in a northern band it appears that this proposed glacial influence is minimal and that the danube loess is essentially mountain loess derived from the alps the carpathians the sudeten mountains and other high regions the danube system is a classic example of a river controlling loess distribution

aeolian dust dynamics in central asia during the pleistocene driven by the long term migration seasonality and permanency of the asiatic polar front loess paleosol sequences preserve detailed archives of climate change reflecting the dynamics of aeolian dust sedimentation and the paleodust content of the atmosphere the detailed investigation of particle size distributions psds of windblown sediments is an increasingly used approach to assess the paleorecord of aeolian dust dynamics the central asian loess belt offers the potential to reconstruct pleistocene atmospheric circulation patterns along an adjacent west east transect within interior eurasia through granulometric studies in this study we present the aeolian dust record of the loess sequence at remisowka se kazakhstan which reflects a detailed signal of glacial interglacial climate and atmospheric dynamics in central asia on the basis of radiocarbon and amino acid geochronologic data long term semicontinuous trends in the aeolian dust record of the last glacial cycle are observed and interpreted to reveal their paleoclimate signal in consideration of the modern synoptical atmospheric circulation patterns and aeolian dust transport in central asia it is likely that the observed trends reflect the long term migration seasonal duration and permanency of the polar front during the late pleistocene previously published models which focused on the reciprocal glacial interglacial influence of the zonal westerlies and the asiatic high on the aeolian dust transport in central asia were overly simplified and should be modified to include the major influence of the asiatic polar front as the polar front activity is intimately connected with the development and position of the interhemispherically active high level planetary frontal zone hpfz the presented data give insight to long term aeolian dust dynamics and climate variability of interior eurasia which are linked with interhemispheric climates

reconstructing palaeoenvironments on desert margins new perspectives from eurasian loess and australian dry lake shorelines abstract desert margins preserve evidence of more extensive arid conditions in the past and represent global hot spots with respect to climate change the balance of scientific evidence now suggests that dryland landscape reactivation did not correspond simply to ice age aridity peaks as previously assumed this paper provides a new perspective on and more nuanced understanding of desert marginal landscapes as palaeoenvironmental archives the two case studies represent ends of a sediment availability spectrum both environments experience substantial spatial and temporal variability in deposition with implications for reconstructing past environments at individual sites recently generated chronostratigraphic data from the dry subhumid dobrogea loess romania are synthesised to provide quantitative insights into the spatial and temporal organisation of loess plateaux loess accumulation peaks during the lgm and mis4 but not at all sites accumulation rates vary substantially between sites comparison of geographical context yields no clear driving mechanism for this variability secondly two transverse lunette dunes in semi arid willandra lakes australia yield comparable chronostratigraphies and distribution of stratigraphic units a first attempt is made to identify changes in wind regime through time on the australian desert margins and suggests that high latitude climate forcing may have acted upon semi arid australia over millennial scales the novel perspectives generated from the new datasets provide unprecedented insights into past climate circulation and land surface processes along desert margins these new perspectives coupled with the new geochronological and quantitative palaeoclimate proxy tools now available represent the next frontier for palaeoenvironmental research on desert margins

initial quartz osl and dust mass accumulation rate investigation of the kisiljevo loess sequence in north eastern serbia abstract the thick and apparently continuous loess palaeosol sequences in the vojvodina region of northern serbia are recognized and well understood as some of the oldest and most complete terrestrial european palaeoclimatic archives by contrast there are few published records for loess profiles from other regions in serbia here we address this knowledge gap by investigating an 8 m thick loess sequence exposed near the village of kisiljevo in north eastern serbia describing the pedostratigraphy and environmental magnetic signatures in detail and placing these within a chronologic framework using quartz optically stimulated luminescence osl on the 4 11 and 63 90 m size fractions our results show dust accumulation over the last c 32 ka with substantial primary loess accumulation during the early holocene prior to the formation of the modern soil we applied two age depth modelling approaches to estimate dust mass accumulation rates the bacon r software and admin model both yield high accumulation rates especially during mis 2 averaging 550 600 g m 2 a 1 which exceed estimates for other investigated loess sequences in the region

mis3 2 millennial oscillations in greenland dust and eurasian aeolian records a paleosol perspective abstract since their discovery the abrupt climate changes that punctuated the last glacial period 110 6 14 62 ka have attracted considerable attention originating in the north atlantic area these abrupt changes have been recorded in ice marine and terrestrial records all over the world but especially in the northern hemisphere with various environmental implications ice core records of unprecedented temporal resolution from northern greenland allow to specify the timing of these abrupt changes which are associated with sudden temperature increases in greenland over a few decades very precisely the continental records have so far been mainly interpreted in terms of temperature precipitation or vegetation changes between the relatively warm greenland interstadials gi and the cooler greenland stadials gs here we compare records from greenland ice and northwestern european eolian deposits in order to establish a link between gi and the soil development in european mid latitudes as recorded in loess sequences for the different types of observed paleosols we use the correlation with the greenland records to propose estimates of the maximum time lapses needed to achieve the different degrees of maturation and development to identify these time lapses more precisely we compare two independent ice core records 18 o and dust concentration indicating variations of atmospheric temperature and dustiness in the greenland area respectively our method slightly differs from the definition of a gi event duration applied in other studies where the sharp end of the 18 o decrease alone defines the end of a gi we apply the same methodology to both records i e the gis are defined to last from the beginning of the abrupt 18 o increase or dust concentration decrease until the time when 18 o or dust recur to their initial value before the gi onset determined both visually and algorithmically and compare them to published estimates of gi timing and duration the duration of the gi and consequently the maximum time for paleosol development varies between 200 and 4200 years when visually determined and between 200 and 4800 years when estimated algorithmically for gi 17 to 2 i e an interval running from 60 ka to 23 ka b2k age before 2000 ad furthermore we investigate the abruptness of the transition from stadial to interstadial conditions which initiates the paleosol development the average transition duration is 55 4 16 1 56 8 19 6 years when determined visually and 36 4 13 4 60 00 21 2 years when determined algorithmically for the 18 o dust concentration the 18 o increases correspond to a mean temperature difference of 11 8 c on the top of the greenland ice sheet associated with substantial reorganizations of the ecosystems in mid latitude europe

changes in sediment flux and storage within a fluvial system some examples from the rhine catchment the rhine river system can look back on a long history of human impact whereas significant anthropogenic changes to the river channel started only 200 years ago the impacts of land use have been felt for more than 7500 years here we review results from several case studies and show how land use change and climate impacts have transformed the fluvial system we focus on changes in sediment delivery pathways and slope channel coupling and show that these vary in time and depend on the magnitude of a rainfall event these changes must be accounted for when trying to use sediments as archives of land use change and climatic impacts on fluvial systems for example human impact is recorded in slope deposits only as long as rainfall intensity and runoff generation do not exceed the threshold for gullying similarly climatic impacts are only recorded in alluvium when both the landscape is rendered sensitive by human activities e g deforestation and rainfall thresholds for gullying are exceeded copyright 2003 john wiley sons ltd

loessification and hydroconsolidation there is a connection abstract loessification can be defined as the acquisition of loessic characteristics by ground systems hydroconsolidation in this context is the collapse of the loess ground structure under the influence of loading and wetting loess on aeolian deposition is metastable a pre requisite for eventual collapse the actual collapse mechanism is dependent on the presence of a critical amount of clay mineral material at major particle contacts this clay accumulates via post depositional processes processes which can be described as part of loessification and as a contribution to collapsibility studies at ospringe in kent england support observations made in the bohemian massif in the czech republic about the nature of the loess ground system and the role of clay minerals and calcite crystals fragipan formation another important post deposition event could depend on hydroconsolidation in loess ground

silt production as a function of climate and lithology under simulated comminution production of the silt sized particles composing loess represents a critical step in its ultimate formation but the volume and rate of production in different settings remain underdetermined this study addresses the influence of climate and source lithology on silt formation by subjecting natural alluvial fluvial sand from systems characterized by varying climatic setting to simulated comminution bulk samples from comparable transport distances were collected from a hot arid california desert alluvial system hot humid puerto rico fluvial system and cold humid norway proglacial fluvial system and sieved to isolate the coarse very coarse sand fraction for experimental milling source rocks in all three systems consist of granitoids with some contributions from foliated coarse grained metamorphic rocks gneissic and schistose in norway results indicate that contributions from coarse grained foliated lithologies impart a negligible effect on rate of silt production from the sand starting material climatic setting imparts no significant difference on sand durability but influences clay production at later stages of comminution for the puerto rico sample presumably owing to the effects of deep chemical weathering prior to physical transport comminution and silt production in all experiments exhibit exponential decay wherein rapid initial rates diminish with time this is interpreted to reflect the effects of the dynamic milling conditions particle size and distribution and slurry viscosity as well as particle strength with the latter including both relative strengths of different minerals in general and the influences of lattice defects and microfractures in quartz in particular empirical observations reveal that silt fractions of the natural alluvial fluvial samples collected at comparable transport distances 5 7 km in the respective systems exhibit significant differences bulk sediment samples from the norwegian proglacial system contain substantially more silt 3 10 times than either of the other two localities implying a significant difference in the natural processes operating to generate silt in these different field settings we suggest this difference reflects the efficacy of glacial grinding in silt production

making the material the formation of silt sized primary mineral particles for loess deposits abstract in 1911 e e free wrote it may be well to point out that there are really two problems of the loess a problem of the origin of material and a problem of deposition the problem of the origin of material has been relatively neglected in comparison to problems of deposition of the formation of deposits and latterly in comparison to studies of loess stratigraphy if we are to understand the true nature of loess this fascinating material we need to be aware of all the significant events in the processing of the particles which form a deposit a large amount of silt sized primary mineral material has to be produced to make a loess deposit loess is a quaternary phenomenon and we see the entire process being completed in quaternary times some powerful quaternary forces are able to produce very large amounts of granular material glacial grinding vigorously supported by smalley 1966a provides an obvious source for some loess material but the vast deposits of north china and central asia have no obvious glacial connection however they are adjacent to high asia a region of vast tectonic activity and an enormous release of terrestrial energy in the last several million years high asia is a large producer of loess silt much of which finds its way south to make the ganges delta but large amounts are moved north and east to make huge loess deposits africa presents a problem recent work e g coude gaussen 1987 suggests that there is a region of peri saharan loess but earlier observations e g penck indicate quite clearly that the sahara region is free of loess rathjens 1928 in his study of tripolitania indicated the presence of loess like deposits and described their nature but he did point out that 90 of the granular material was greater than 100 pm in diameter which would remove it from a strict loess definition on the soil taxonomy map of africa there is a belt of soil d3 which could include considerable loess deposits it stretches from the matmata loess in tunisia across northern libya to the western part of the egyptian coastal region if d3 contains loess this points to a genuine desert loess particle producing mechanism operating in the sahara

silt 2 62 μm 9 4φ the particles in finer grained detrital sediments are usually composed of quartz they fall into two size grades sand 2 mm 62 m and silt 62 m 2 m these size gradings conceal important geological processes since there are geological controls on both the quartz sand and silt populations sand nature is largely controlled by geochemical reactions for example in cooling granite from which it is eventually released by weathering action the quartz is among the last part of the rock system to solidify and the eutectic like reaction which occurs ensures that the quartz exists as small crystalline units each suffering considerable cooling and recrystallisation stresses silt is broken quartz and has traditionally been considered to lack a specific geological control the situation is confused by the large range of materials that fall into the size category but there do seem to be distinguishable modes and possibly comminution limits within the 60 m span the controls operating in this size range are probably the critical concentration of moss defects in the quartz particles moss postulated the formation of specific crystal defects in the quartz formed in granites these affect sand formation and it is possible that they also control the mode size of silt particles within the silt range there may be several usefully definable populations as moss proposed for sand the quaternary appears to be a silt rich period due to tectonic and glacial activity but silt production is apparent throughout the sedimentary record very long term silt producing processes are required to produce silt in nature on a large scale very energetic processes are required many processes that are believed to generate silt particles have been listed however large scale production is essentially due to glacial grinding or to intense weathering processes in high cold tectonically active mountain regions the region of high asia of crustal overlap is a major generator of silt particles these form the productive alluvial soils of north india most of the nation of bangladesh the loess deposits along the syr darya and amu darya rivers in central asia and the great loess deposits of north china some claims have been made for silt production in hot deserts large amounts of very fine aerosolic dust are produced but in terms of loess sized particles this is a small scale process and leads to modest disputed deposits the loess deposits around the sahara usually have smaller mode sizes e g nigeria or larger mode sizes e g libya tunisia than the true chinese mode at 25 m this paper aims to introduce the distinguishing properties of sand and silt discuss in detail the possible processes of silt formation in relation to the evidence of what is produced describe the major silt populations and conclude on the most likely formation process es in particular three silt ranges are discussed in relation to the r size diagram c 2 5 m d1 20 30 m and d2 60 m these can represent canadian quickclay qq chinese loess and the ideal loughborough loess ll and north african loess nal it is intended that this paper will put into context the diverse work in the area and in so doing shed light on what is an often overlooked subject

origin and emplacement of the loess deposited in northern brittany and under the english channel abstract the origin of the loess deposited in northern brittany can be only understood if its original extension is carefully delineated marine sedimentological data show that there are no loess deposits under the english channel because they have been removed during the various pleistocene and holocene transgressive episodes however indirect evidence and particularly study of the submerged pleistocene conglomerate which resulted from the cementing of beach deposits overlain by loessic silts when the sea was at a lower level supports the idea that loess did not extend north of the axis of the english channel the northern limit of the loess deposits corresponds with the hurd deep their southern boundary is located onshore and coincides with the north armorican coastal loess belt comparison between the modern garnet rich sands sampled in the centre of the western and eastern english channel with loess of normandy and brittany show that the main part of the onshore loess originated in the fluvial sediments accumulated in the channel river transportation of the dust from the valley of this river to normandy and brittany indicates southward oriented paleo winds the contributions of frost shattering of the offshore chalky formations the in situ detrital particles produced in northern brittany and the effects of the glacial grinding which occurred in southern england seem to be rather limited

paleoenvironments from robust loess stratigraphy using high resolution color and grain size data of the last glacial krems wachtberg record ne austria abstract the complex interplay of dust sedimentation pedogenesis and erosion reworking in the formation of loess paleosol sequences lps challenges paleoenvironmental proxies here we show that color and grain size are essential parameters characterizing loess profiles and support robust stratigraphies as a basis for reconstructions in the context of local geo ecological and large scale paleoclimatic evolution detailed paleoenvironmental records from the period since the arrival of anatomically modern humans to the last glacial maximum are scarce in the alpine surroundings the c 7 5 m thick lps krems wachtberg ne austria known for its well preserved upper paleolithic context at a depth of 5 5 m formed between 40 and 20 ka bp by quasi continuous dust sedimentation interrupted by phases of incipient pedogenesis and local reworking the new kw2015 composite is based on three sections studied and sampled at 2 5 cm resolution color and grain size data support a robust stratigraphy for reconstructions of the pedosedimentary evolution the marked transition from oxidized to reduced paleosols of kw2015 around 34 35 ka corresponds to the middle to upper pleniglacial transition as part of a general cooling trend from marine isotope stage mis 3 to 2 intensely modulated by millennial scale climatic fluctuations as recorded in the greenland ice core data the distinct response of kw2015 to these trends highlights that reconstructing lps evolution based on a robust stratigraphy is a prerequisite to paleoenvironmental proxy interpretation

the loess sequence from remisowka northern boundary of the tien shan mountains kazakhstan part i luminescence dating abstract similar to the chinese loess the loess deposits surrounding the high mountain regions of central asia play an important role in understanding the climate and environmental change during the pleistocene in eurasia despite their thickness and widespread distribution the loess deposits in southeast kazakhstan have so far not been investigated in detail the remisowka loess palaeosol sequence is located in the vicinity of the north tien shan mountains at an altitude of 1070 m above sea level in the profile under study nine loess layers were distinguished intercalated by eight pedocomplexes and so indicating a similar cyclicity like the loess palaeosol sequences in central asia and china at the remisowka section 12 loess samples were taken to set up a more reliable chronological model for the section using a luminescence dating approach polymineral fine grains were investigated by infrared optically stimulated luminescence applying the multiple aliquot additive dose protocol preliminary fading experiments were carried out for one sample taken from the uppermost loess layer while the results of the uppermost layer are in agreement with geological age estimates and indicate a correlation to the late glacial age underestimation is very likely for the samples below the first weak palaeosol no significant age increase with depth was recognised the reason for this age underestimation is not yet fully understood but could be related to anomalous fading further methodological approaches are necessary as well as a combination of different chronometric techniques for improvement of the results

paleoclimate and weathering of the tokaj hungary loess paleosol sequence abstract the tokaj loess paleosol sequence northeast hungary is a well studied site in southeast europe where detailed paleoenvironmental reconstructions of the quaternary have been carried out in this study the geochemical composition of samples from the upper part of the sequence 45 21 ka was analyzed and a variety of commonly used weathering indices and element ratios were applied to estimate weathering intensity a common semi quantitative proxy of paleoclimatic conditions further similarities and differences between these weathering indices and their sensitivity to changes in paleoclimatic conditions were assessed results indicate that all of them accurately track changes in weathering intensity and are with minor exceptions very similar to each other based on different transfer functions for major and trace element concentrations xrf mass specific magnetic susceptibility and stable carbon isotopic 13c data mean annual paleotemperature and mean annual paleoprecipitation for the time intervals of paleosol formation 45 27 ka and dust deposition 27 21 ka were calculated results differ depending on the respective transfer function and method but agree with x 13c based or slightly overestimate xrf based previously published paleoclimate data of the region xrf and 13c based results converge to a mean annual temperature mat range of 8 5 10 c paleosol and 8 9 c loess and a mean annual precipitation map range of 700 900 mm a 1 paleosol and 550 700 mm a 1 loess based results are most consistent with literature data and yield mats of 8 4 c paleosol and 6 6 c loess and maps of 300 500 mm a 1 paleosol and 220 mm a 1 loess

downstream changes of alpine zircon fission track ages in the rhone and rhine rivers zircons from 13 sediment samples from the rhone and rhine drainages were dated by the fission track method to study downstream changes in detrital fissiontrack grain age distributions in large river systems draining the european alps the orogen parallel rhone river shows a zircon fission track grain age distribution similar to that in its alpine source areas this signal is well preserved because there are alpine sources along its full length and input from non alpine sources is small in contrast only the headwaters of the north flowing rhine river are located in the alps as a consequence alpine derived zircons which are distinguished by young fission track ages become progressively diluted downstream by older ages from zircon sources external to the alps nevertheless the alpine component is persistent and can easily be detected in sediments more than 1000 km downstream at the rhine delta these results demonstrate that fission track dating of detrital zircons can provide useful information about orogenic processes even where sediments have been transported hundreds of kilometers from the orogenic source crossing ephemeral lakes and subsiding basins deposits along the lower reaches of the river appear to have a short residence time 1 myr and thus many of these deposits serve to smooth out variations in the supply of sediment from fast eroding heterogeneous sources in the alpine headwaters of these drainages for the rhone and the rhine rivers we show that fast erosion in the alps accounts for most of the sediment load this finding supports a widespread observation that the sediment in most large continental drainages is usually derived from a small part of the drainage where uplift relief and erosion rates are greatest

late pleistocene changes in terrestrial biomarkers in sediments from the central arctic ocean abstract biomarkers in late pleistocene sediments collected from the integrated ocean drilling program iodp arctic coring expedition acex hole m0004c central arctic ocean were investigated the major biomarkers are long chain n alkanes n fatty acids and n alkan 1 ols indicating fresh organic matter om derived predominantly from higher plants the dominance of terrestrial biomarkers is attributed to severe om degradation caused by slow sedimentation in oxygen rich benthic water and or low primary production due to permanent sea ice coverage hopanes representing thermally altered om tend to be abundant in samples with abundant ice rafted debris ird an om rich dark grey layer deposited during marine isotope stage mis 6 contains a significant amount of branched glycerol dialkyl glycerol tetraethers branched gdgts suggesting ice erosion of organic rich continental soil followed by transportation to the central arctic by drifting ice the labile refractory index i e the abundance ratio of long chain n alkan 1 ols to the sum of long chain n alkanes and long chain n alkan 1 ols decreases above the dark grey layer indicating that the om became more refractory this change suggests that coverage of the source region by om rich soil decreased because of extensive glacial erosion during mis 6

tracing the origin of loess in hungary with the help of heavy mineral composition data abstract heavy mineral composition of the fine sand fraction in the hungarian loess sediments provides important data about the closer sources of the loess in the carpathian basin quantitative detrital heavy mineral compositions of 216 loess loess like sediment and paleosol samples were compared to each other and to recent fluvial sands and different cenozoic sands and sandstones of hungary using statistical methods cluster analysis principal component analysis and discriminant analysis usually garnet is the most frequent detrital heavy mineral in the studied loess sections followed by chlorite magnetite epidote and amphiboles old loess and young loess have similar compositions indicating uniform or similar sources based on the similarities the garnet rich loess sediments could originate from aeolian reworking of the floodplain sediments of the danube and other rivers of transdanubia and the local cenozoic sands of the uplifting transdanubian central range and transdanubian hilly region the biotite and tourmaline rich loess in south transdanubia and the loess with high pyroxene content in the north hungarian range had some material from nearby sources weathered granitoids and volcanic rocks respectively or sediments of local rivers which carried detritus of these rocks the new results presented in this paper confirm numerous earlier ideas about the origin of loess in the carpathian basin but also suggest newly identified sources of the loess particles at several locations

contemporary glacigenic inputs to the dust cycle the importance of glacigenic dust in the earth s system during glacial periods is widely acknowledged under contemporary conditions the world s largest dust sources are in low lying hot arid regions and this is where most aeolian research is focused however the processes of dust production and emissions are still operating in cold climate regions particularly in proglacial areas this paper assesses current understanding of the relationship between glacierised landscapes and dust emissions and inputs to the global dust cycle it focuses on how elements in the glacial and aeolian geomorphic sub systems interact to determine the magnitude frequency and timing of aeolian dust emissions and on feedback mechanisms between the systems where they have been measured dust emission intensity and deposition rates in glacierised catchments are very high in some cases far exceeding those in lower latitudes however few studies span long time scales the impact of future glacier retreat on the balance between sediment supply availability and aeolian transport capacity and implications for glacigenic dust emissions is also considered this balance depends on relative spatial and temporal changes in meltwater suspended sediment concentration and wind strengths which promote dust emissions and patterns and rates of soil development and vegetation succession on recently deglaciated terrain which protect sediments from deflation retreat of the antarctic ice sheet could mean that in future glacigenic contributions to the dust cycle exceed those of non glacigenic sources in the southern hemisphere copyright 2012 john wiley sons ltd

loess accumulation in the tian shan piedmont implications for palaeoenvironmental change in arid central asia whilst correlations have been made between the loess of europe and china deposits in central asia have remained largely overlooked by scientific investigation the nature of the relationship between loess accumulation and palaeoclimate at the core of the eurasian loess belt is particularly poorly understood here we reconstruct palaeoenvironmental change in central asia over the last 40 ky based on data from the remizovka loess profile in the northern foothills of the tian shan in southern kazakhstan our interpretations are based on synthesis of chronostratigraphic colour and magnetic susceptibility data supported by chronostratigraphies from two additional sites nearby maibulak and valikhanova all three sites record substantially increased loess accumulation during late mis 3 into the global last glacial maximum glgm at remizovka increased loess flux occurred in two pulses at c 38 25 ka and 22 18 ka with the intervening period involving incipient pedogenesis at maibulak two loess pulses at c 40 30 ka and c 28 22 ka are separated by a weakly developed paleosol which may date to the same time as pedogenesis at remizovka there is additional possible periglacial influence at maibulak from c 40 33 5 ka at valikhanova there is some age overlap between paleosol and loess samples but overall loess accumulation appears to have increased at c 42 35 ka c 30 ka and the glgm with pedogenesis occurring 40 ka and c 32 ka at all three sites holocene loess accumulation is minimal this period is characterised by pedogenesis the chronostratigraphic variability between our sites highlights a need to interrogate climate driven models for loess formation in piedmont environments we interpret our data in the context of regional palaeoenvironmental archives to indicate that loess accumulation increased coeval with mis 3 glacial advance in the tian shan which was facilitated by northward expansion of the asian monsoon and associated increase in precipitation we hypothesise that increased ice volume impeded teleconnections with the temperate zone westerlies to the north these were compressed against the piedmont resulting in increased wind strength and facilitating increased loess flux peak loess accumulation during the glgm occurred under colder drier climatic conditions with reduced but sustained glacial ice volume and persistent influence of the westerlies in the arid central asian piedmont loess belt in the absence of more widespread reliably dated palaeoenvironmental records from the region our data become of critical importance for understanding past environmental conditions in central asia relative to elsewhere in eurasia and globally

last glacial aeolian landforms and deposits in the rhone valley se france spatial distribution and grain size characterization abstract in the rhone valley a north south oriented cenozoic rift in southeast france thick pleistocene loess deposits have been recognized since the beginning of the last century these loess records which are disconnected from the north european loess belt nelb are of significant interest to document the evolution of perimediterranean landscapes and environments during the last glacial to overcome the poor precision of available aeolian distribution maps aeolian deposits were mapped using the topsoil textural database provided by the land use and cover area frame statistical survey project lucas the grain size distribution of aeolian sand and loess was first determined using 116 samples taken from surveyed outcrops then the areas showing a similar grain size composition were extracted from the lucas rasters the resulting map reproduces the conventional maps correctly but suggests a more significant extension of loess in better agreement with the known distribution of outcrops the map shows that the distinctive morphology of the valley dominantly controls the distribution of aeolian deposits the deflation related landforms i e yardangs closed depressions pans and desert pavements are widespread south of narrowings of the rhone valley between latitudes 44 n and 45 n they indicate palaeowinds blowing from the north northwest aeolian sand loessic sand sandy loess and loess deposits successively spread on both sides of the rhone river the loess is characterized by a coarse texture main mode around 60 m strong local thickness 5 m limited extension and abundant bioturbation this preservation results from the persistence of a shrub vegetal cover during the coldest and driest phases of the last glacial that allowed for trapping the saltating and suspended particles close to the alluvial sources

upbuilding pedogenesis under active loess deposition in a super humid temperate climate quantification of deposition rates soil chemistry and pedogenic thresholds abstract although the importance of dust deposition as an integral component of terrestrial biogeochemical cycles is well recognised few studies have directly addressed pedogenic processes associated with dust deposition on the land surface itself and if so mainly as relict features this work addresses this gap by looking at the pedogenic response to an active loess flux gradient in a super humid strong weathering environment on the west coast of new zealand s south island along the gradient seven soil pits were examined for a range of soil physical colour texture bulk density structure roots and chemical properties ph fe o fe d al o soil organic carbon measured to a depth of 50 cm to capture the transitional changes arising from minimal to maximal loess deposition rates maximal deposition rate was estimated to be 28 4 g m 2 y 1 along the gradient towards the highest deposition rate loess free sandy spodosols changed to increasingly more finely textured soils ultimately featuring a two fold increase of silt the pedogenic oxides fe o fe d and al o gradually increased each by 50 and soil organic carbon by 60 these increases were facilitated by continuous accession of loess the loess mixed with organic matter at the surface and became increasingly weathered and leached with the time that it had spent undergoing eluviation subsequently the loess increments were buried within the subsoil as part of an upwardly thickening spodic horizon upbuilding pedogenesis because of the high deposition rates under maximum loess flux spodosol formation became ultimately retarded and an inceptisol formed because loess supply overwhelmed topsoil leaching having also an illuvial subsoil horizon this inceptisol showed the strongest chemical indicators for podzolisation of the gradient soil data from supplementary sites suggested that more developed soils required lower loess fluxes to retard further pedogenic differentiation than younger soils the existence of a loess gradient that is capable of forming distinctive deposits in a super humid environment gives evidence that not only dry arid climates e g during glacials are potentially suitable for the formation of aeolian substrates loess the study indicates enhanced soil organic carbon storage in soils as a result of loess deposition and concomitant pedogenesis

problems and potential of osl dating weichselian and holocene sediments in sweden recent osl dating of various late quaternary deposits in sweden has resulted in several sets of ages that appear inconsistent with geological interpretation they usually overestimate the expected age we explore the problems and potential of osl dating in sweden by analysing quartz osl ages from several known age sites in sweden and by investigating their luminescence properties two difficulties in obtaining accurate and precise ages are incomplete bleaching and low sensitivity quartz incomplete bleaching can give rise to age overestimation but the importance of this effect can be minimised by selecting suitable sediment facies although for some settings unexplained overestimates still remain low quartz osl sensitivity leads to practical problems in measurements and larger uncertainties in dose estimates but not necessarily to systematic age overestimation sites that contain dala sandstone clasts and or sediments that may have had extensive reworking during the quaternary seem to provide high sensitivity quartz we consider such sites to show the most potential for accurate and precise osl dating in sweden

dust deposition and climate in the carpathian basin over an independently dated last glacial interglacial cycle dust deposition and climate in the carpathian basin over an independently dated last glacial interglacial cycle

engineering geology of loess and loess like deposits a commentary on the russian literature loess and loess like deposits were much studied in the soviet union and are currently under investigation in russia and surrounding countries there is a vast literature in russian which touches on all aspects of loess science and technology in particular the studies of the origin of collapsibility are almost totally in russian and of course studies on the various regions of russia and the countries of the former soviet union fsu appear in russian this review looks at the literature in russian and attempts to pick out key contributors major topics and works and to identify the critical regions and zones of investigation because so many regions of the fsu had people living on loess ground there is a vast literature on engineering geology and ground engineering topics and this tends to dominate all the literature on loess in russian following russian practice the fine grained deposits under consideration are divided into loess and loess like deposits three main topics are recognised across the whole spectrum of loess research formation and distribution of loess deposits stratigraphy cyclicity and palaeoclimatology and engineering topics in particular hydrocollapse and subsidence and we concentrate on the engineering geology topics an attempt is made based on the map of abelev and abelev abelev yu m abelev m yu 1968 fundamentals of design and construction on collapsible macroporous soils 2nd ed stroiizdat moscow 431 pp in russian of collapsing loess deposits to define seven loess regions within the geographical limits of the old ussr the seven regions are those where geotechnical problems might be expected

late pleistocene loess palaeosol sequences in poland and western ukraine abstract polish and nw ukrainian loess covers are situated along the northern margin of the central part of the european loess belt because of their intermediate geographic position they form a bridge for loess studies in eastern and western europe fifteen loess soil sequences representing the last interglacial glacial loess cycle were investigated using a new methodological approach elaborated for this purpose the thickness of the late pleistocene sequences ranges between 4 and 14 m all these profiles were sampled in vertical continuous sections at close intervals 5 10 cm and documented with respect to their sedimentology palaeopedology and stratigraphy the main litho and pedostratigraphic units were established during field investigations loess palaeosol sequences confirm the general instability of the last glacial climate the representative late pleistocene interfluve loess sequence in the study area consists of four units two polygenetic palaeosol complexes and two calcareous loess units within these loess units two generations of ice wedge casts indicate twofold expansion and disappearance of permafrost during the last glacial period this evidence confirms the correlation of main terrestrial events of the late pleistocene loess sequences with the marine record the last glacial loess sequences in poland and nw ukraine are of crucial importance for palaeogeographic reconstructions of european loess areas