centrifuge model study on settlement of strip footing subject to rising water table in loess owing to man made activities and natural conditions the groundwater table experiences considerable changes in lanzhou centrifugal model tests were performed to investigate the settlement of strip

loess and life out of earth abstract loess is a homogeneous typically nonstratified porous friable slightly coherent often calcareous fine grained silty pale yellow wind blown aeolian and often by water reworked sediment that is distributed on continents world wide recent studies have highlighted the importance of biological loess crusts in trapping and transforming aeolian material into loess and also in prevention from wind and water erosion of deposited material some planets and satellites in our solar system are characterized by conditions comparable to those related to loess formation in terrestrial environments given the requirements for loess deposition on earth this study aims to ask the following questions 1 if loess like sediment formation is possible outside earth what are the mechanisms of sediment deposition and preservation 2 could the possible loess like sediments be stabilized through the activity of extraterrestrial equivalents of biological loess crusts found on earth as loess formation on earth is related to biological activity we propose a new direction in the search for extraterrestrial life evidence about extraterrestrial loess might indicate extraterrestrial life connected to loess formation on the basis of comparative analysis of some astrophysical conditions of seven celestial bodies we propose mars and titan and possibly venus and io to be assessed for evidence of loess deposition and the possible presence of related life forms and their biomarkers following recent advances in our understanding of terrestrial loess deposition we propose new indicators of extraterrestrial life research biomarkers in loess cyanobacterial and other microbial

results of paleoecological studies in the loess region of szeged othalom se hungary abstract new results of sedimentological magnetic susceptibility geochemical radiocarbon and malacological analysis from a typical and an infusion loess section are presented from se hungary the geologic and geomorphologic value of the area is that aeolian typical loess accumulated on sand dunes that formed during mis3 while in the interdune depressions on the top of lacustrine deposit series infusion loess developed as the two types of loess interfinger it is the first demonstration that the two types of loess formed during the same time period isochron in different environments heterotype at the end of mis3 and during mis 2 between 33 000 13 000 cal bp a temperate steppe forest steppe environment characterized the loess surface of the se great hungarian plain during the first interstadial phase of mis2 a pinus sylvestris charcoal rich paleosol layer developed on the loess covered surface of a wind blown sand hummock while in the interdune depressions a pond phase developed after the formation of the paleosol layer on the surface of the loess covered wind blown sand hummock during the heinrich 2 event vertigo modesta vallonia tenuilabris indicate a cold steppe forest steppe environment and a deeper and colder lake phase in the interdune depressions after that a short microinterstadial phase developed and a pupilla triplicata chondrula tridens dominated temperate steppe forest steppe environment evolved on the terrestrial surface between 23 000 21 000 cal bp after 21 000 cal bp in the last glacial maximum lgm the environment completely changed the average dust accumulation accelerated and coarse silt 0 02 0 06 mm became dominant as a result the lake stage transformed to a marshy environment while on the land area shade loving including closed forest environment preferring mollusca taxa appeared such as vestia turgida vitrina pellucida and mastus venerabilis based on the mollusca fauna composition humidity increased during the cooling of the lgm horizon forestation started and a boreal forest steppe evolved at the study site during the post lgm the interdune depressions filled and aeolian loess layers developed formation of the infusion loess occurred between 24 000 17 000 cal bp loess formation lasted until the beginning of the late glacial maximum last permafrost maximum and ended in a forest steppe environment with boreal central european holarctic palearctic and continental mollusc fauna elements

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

an integrated rock magnetic and geochemical approach to loess paleosol sequences from bohemia and moravia czech republic implications for the upper pleistocene paleoenvironment in central europe abstract two central european loess paleosol sequences mis 6 2 from central bohemia zem chy and southern moravia dobsice situated in the important climatic transition zone between the oceanic atlantic and continental climate regimes were investigated for rock magnetism geochemistry grain size and micromorphology in both sites the magnetic profile shows good agreement with the standard model of magnetic enhancement in paleosols as established in the chinese loess the magnetic signal is dominated by the presence of fine grained magnetite and maghemite formed in situ and controlled by the intensity of soil formation magnetic proxies corresponded to proxies of chemical weathering and leaching intensity such as the chemical index of alteration cia the cation exchange capacity cec and the rb sr ratio correlation coefficient r 0 6 0 93 during the whole lower weichselian mis 5d 5a and in general also during the pleniglacial mis 4 2 nevertheless for the eemian period mis 5e this relationship was not always valid either due to weak magnetic enhancement at dobsice or even weak depletion of the magnetic minerals with soil formation at zem chy the presented data demonstrate that magnetic signals can be overprinted more easily than chemical proxies during later diagenetic events and are hence not in all cases reliable for deciphering paleoclimate changes during all periods of the studied time interval rock magnetic geochemical and micromorphological results suggest drier conditions in southern moravia compared to central bohemia during the weichselian glacial probably due to the more continental climate in southern moravia

distribution and genetic types of loess landslides in china abstract in this study 14 544 loess landslides collected from the loess plateau of china are used to reveal their distribution and origins main factors considered include landslide density regional tectonics soil properties geomorphic structure rainfall distribution seismic activity and human activity based on these factors the loess plateau is divided into eight zones with high possibilities of landslides that are classified into six genetic types the first genetic type of clustering distribution of loess landslides is related to several main regional active faults the second type is related to broken pieces of loess geomorphic structures the third type is considered to be due to unloading of the geomorphic peripheral slope that can cause the internal structural plane to open and thus controls the prototype and scale of the loess landslide change of hydrogeological conditions in the slope softens the loess pedestal and the slippery layer forming a softening zone and thus controlling the shear crack and slip model of the fourth type of loess landslides the fifth type is due to seismic activities that can generate additional stress to the earth s surface and landform slopes causing the opening of joints and seismic liquefaction the last type of landslides is caused by human activities by changing the geological structure hydrogeological conditions and the inner stress balance of slopes

fe mn nodules in a southern indiana loess with a fragipan and their soil forming significance abstract little is known about how fe mn nodules vary in relation to pedogenetic horizons in soils derived from loess in this investigation nodules were collected according to soil genetic horizons from a fragiudalf in loess at southeast purdue agricultural center sepac in indiana and physical chemical micro and macromorphological features of nodules and their soil matrix were determined as a function of soil depth the quantity chemical composition and micromorphology of the nodules varied with genetic horizons the ap horizon was found to contain the largest amount by weight of nodules 25 43 g kg and this was likely due to soil erosion after the ap horizon the 2btx1 and 2btx2 horizons had the greatest content of fe mn nodules by weight nodules had lower concentrations of sio2 al2o3 k2o tio2 mgo na2o and cao in contrast fe2o3 mno and p2o5 in nodules showed clearly greater concentrations than that in the corresponding soil material the sio2 content decreased with nodule size whereas fe2o3 and mno increased the least depletion of sio2 in nodules of 1 2 mm n2 and 0 5 1 mm n1 was in the bt2 horizon and was greatest in the 2btx2 the al2o3 had accumulated in the n2 and n1 nodules within the ap horizon and in the n2 within the 2btx2 while other horizons were depleted of al2o3 brown nodules had a small mn fe ratio 1 the internal morphology of the nodules also varied with mn fe ratios the fungal hyphae or bacteria resulted in honeycomb cell cone or dendritic structures the cell and cone morphology required large mn fe ratios low ph and high content of ald the scanning electron microscopy sem analysis illustrated an elemental distribution trend such that the mn was centralized in the nodule internal structure whereas fe was concentrated towards the exterior the band structure of nodules likely formed in response to seasonal wetting and drying as an accretionary process three basic formation stages for a well developed nodule can be inferred which correspond to different soil forming environments 1 fe enrichment for nucleus formation in wet soil 2 mn enrichment in an intense dry soil and 3 fe banding enrichment in a slightly dry soil nodule formation occurred synchronously with soil pedogenesis and can therefore be used as a proxy for understanding soil pedogenesis and the environment under which it occurred

a late pleistocene palaeoclimate record based on mineral magnetic properties of the entrance facies sediments of kulna cave czech republic summary kulna cave is located in the moravian karst a well developed karstic region formed in devonian limestones in the eastern part of the czech republic the entrance facies sediments in the cave consist of interbedded layers of silts loess and clay rich silts loam that were either directly blown into the cave entrance or redeposited in the cave by slope processes during the last glacial stage the layers of loess and loam overlie fluvial sands and gravels deposited during the last interglacial previous research at kulna concentrated on the archaeology palaeontology and dendrology of these entrance facies sediments from these data palaeoenvironmental conditions in the vicinity of the cave were reconstructed our results suggest that susceptibility variations and in particular variations in pedogenic susceptibility yield a more detailed record of the palaeoenvironmental conditions at the cave during the last glacial stage magnetic susceptibility was measured on approximately 700 samples collected throughout three well studied profiles in the cave entrance the record is well defined and correlates from one profile to another mineral magnetic measurements fd arm sirm s ratio t suggest that variations in the kulna sediments from the last glacial stage are controlled by the concentration of magnetite and or maghemite formed during pedogenesis after the removal of the effects of fine carbonate debris and detrital ferromagnetic minerals on the bulk record we obtained a record of pedogenic susceptibility p that serves to quantify the concentration of magnetic minerals formed during pedogenesis therefore p can be thought of as a proxy reflecting the intensity of pedogenesis which in turn is controlled by climate our p record is also in good agreement with the median grain size record of the kulna sediments another proxy for climatic change we suggest that in the case of kulna p is more sensitive to climate change than bulk the kulna pedogenic susceptibility record shows variations on both long and short timescales the long term trends are in good agreement with the deep sea specmap record while the short term oscillations correlate well with rapid changes in the north atlantic sea surface temperatures our results suggest that central european climate during the last glacial stage was strongly controlled by the sea surface temperatures in the north atlantic short term warmer events and perhaps higher precipitation over the mid continent increased the intensity of pedogenesis given the number of independent climate proxies determined from the entrance facies of the cave and their high resolution kulna is an extremely important site for studying late pleistocene climate

grain size of fine grained windblown sediment a powerful proxy for process identification abstract dust transport by the wind is not a uniform process but may occur in different modes according to source area conditions and transport height and distance subsequently these differences are expressed in terms of grain size and fluxes of the aeolian deposits transport distances may vary from several tens of meters to thousands of kilometers while the height accordingly may vary from meters to more than thousand meters a relation with grain size distributions may be established on the base of type occurrences of different loess facies three main loess populations and several subpopulations of primary windblown origin may be defined according to their grain size dominated by fine sand to very coarse silt silt and very fine silt to clay respectively each of them reflects a specific aeolian process and transport conditions it follows that the grain size distribution of a loess deposit is an excellent proxy for the reconstruction of aeolian processes and wind circulation patterns apart from primary pure wind deposition loess may also be affected by secondary post depositional processes examples are settling of loess particles in a lacustrine setting and reworking by rivers or surface runoff although the primary loess characteristics are maintained reworking processes leave also their imprint in the grain size distribution as a useful tool for secondary process identification

coralline algal reef frameworks published and unpublished accounts of coralline algal reef frameworks are reviewed the descriptions are divided into frameworks constructed from crustose coralline algae and those constructed from branching corallines crustose frameworks are briefly described and illustrated from the miocene of malta recent coralligene from the mediterranean eocene reefs from spain recent algal reefs of st croix u s virgin is and algal reefs from bermuda branching frameworks are briefly described and illustrated from the recent maerl of the ne atlantic recent mud mounds from florida recent algal reefs from st croix and recent algal ridges on pacific reefs crustose and branching frameworks show an increase in strength of construction early submarine cements and macro borers and a decrease in erodibility from low to high energy environments the occurrence of genera in coralline frameworks is primarily controlled by their geographic and water depth ranges the construction of coralline frameworks is seen as the result of competition for living space on shallow marine hard substrates

late quaternary aeolian sedimentation in central and south eastern tibet abstract the geomorphology and the cover sediments in the central and south eastern part of the tibetan plateau provide information about climatic change luminescence dating of aeolian and colluvial silts on top of different moraine sequences provides the first indications for the timing of these sediments during the late quaternary and holocene although there is a widespread cover of aeolian mantles in tibet only a few papers have focussed on them up to now samples from silt layers on top of pleistocene moraines or solifluction debris from central and southern tibet at elevations above 4000 m asl provide early holocene ages in most sections the aeolian silt on top of the bomi moraine in southeastern tibet situated at an elevation of about 3000 m asl provides an age of 25 ka according to geomorphological investigations the bomi moraine dates from the last ice age which can be confirmed by the luminescence data moreover one sample from a silt layer in between gravel layers xainxa is also pleistocene in age according to its sedimentary and geomorphological situation in the tibetan plateau pleistocene loess mainly occurs below 4000 m asl the holocene material a more sandy silt lying above 4000 m asl however aeolian material capping the moraines provides only minimum ages for the terminal moraines the time interval between glacier retreat and the accumulation of aeolian sediments may be several thousand years the most important fact is the trapping of dust in general lakes and a denser vegetation cover are or were the main traps for the typical loess found in the mountain areas of the tibetan plateau

loess in europe mass accumulation rates during the last glacial period abstract upper pleistocene loess palaeosol sequences provide excellent high resolution terrestrial archives of climate forcing due to improvements in numerical age determinations especially in luminescence dating methods a more reliable time based reconstruction of the past climate and environmental change has become available for the loess record in europe chronological information was collected from 43 sites along a northwest to southeast transect in europe thirty three of these sites had sufficient age information to allow estimation of mass accumulation rates and it was possible to isolate the mass accumulation rates of primary loess during the last glacial period 28 13 ka bp at 21 of these locations these sites fall along a coarse climatic gradient from the relatively coastal climate of belgium and france to the drier more continental climate of central europe interpreting mass accumulation rates of loess in terms of this climatic gradient is not straightforward as these deposits are dominated by sources in floodplains and large river systems thus accumulation rates are influenced strongly by regional wind and precipitation patterns but mostly by the availability of glacially derived material from the alps and the periglacial terrains that characterized european fluvial systems during and immediately following glaciation

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

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

late quaternary loess like paleosols and pedocomplexes geochemistry provenance and source area weathering manasbal kashmir valley india abstract the late quaternary loess and loess like deposits in kashmir valley are natural archives that have preserved paleoclimate and paleoenvironmental records of the region we present a loess like paleosol located along the margin of the manasbal lake ganderbal which was studied in detail for understanding the pedological processes and reconstructing the late quaternary soil formation in this paper we present loess like paleosol formation of a nearly 10 6 m thick sequence exposed along the margin of manasbal lake ganderbal district srinagar kashmir geochemical and textural data of this loess like sedimentary sequence fluctuate reflecting the varied depositional processes operating in the valley differential intensity of weathering and processes of pedogenesis weathering indices such as chemical index of alteration chemical index of weathering and plagioclase index of alteration reveal weak to moderate weathering of the parent material provenance discrimination diagrams of the present study disclose that the manasbal loess like paleosol sediments are derived from the mixed source rocks suggesting a variety of provenance with variable geological settings which apparently have undergone weak to moderate recycling processes the manasbal paleosol horizons have been dated by the optically stimulated luminescence osl method to the marine isotope stages mid mis 3 41 7 8 0 ka and late mis 2 14 6 3 8 ka during the mis 3 period the climate was wetter forming a strong ahbtk paleosol as inferred from the geochemical data a steady increase in the caco 3 content and c n ratio in the paleosols from 6 50 m mis 3 indicates arid and drier climatic conditions the area around manasbal lake incised because of climate change and neotectonic activity since post 14 ka

the agh band loess palaeosol sequence a terrestrial archive for climatic shifts during the last and penultimate glacial interglacial cycles in a semiarid region in northern iran abstract the northern iranian loess profiles host important information on quaternary climate and palaeoenvironmental changes in the region they build an important link between the eurasian loess belt and european and central asian archives due to a climatic gradient with decreasing precipitation from the west to the east and from the south to the north loess palaeosol sequences formed synchronously under different climatic conditions can be studied over short distance in the iranian caspian lowland the agh band profile is located in the so called iranian loess plateau a semi arid region with 200 350 mm annual precipitation the loess deposits at agh band reach a thickness of 60 m an about 50 m thick step profile was prepared and the litho pedostratigraphy was investigated samples for laser diffractometry grain size measurements were taken every 2 cm the magnetic susceptibility was measured in 4 cm intervals and the caco3 content in 8 cm intervals to establish a chronological framework a pirir290 luminescence dating approach was applied to the 4 11 m polymineral fraction the results show that the agh band profile yields a climate archive reaching from mis 7 to mis 2 several chronological hiatuses of some 10 ka show that periods of intense loess accumulation were interrupted by phases of only minor loess sedimentation and or erosion the agh band profile is subdivided by several shifts in grain size distribution the coarsening and fining up trends correlate with increasing and decreasing wind velocity respectively in the central part of the agh band loess sequence a weakly developed palaeosol is preserved which was developed at around 80 ka furthermore the loess deposits formed from about 100 ka to 60 ka ago show banded structures a pedocomplex including two well developed palaeosols consisting of bw y horizons and a cb horizon as well as intercalated loess can be found in the lower part of the sequence also evidenced by the increased values of magnetic susceptibility the corresponding luminescence age estimates indicate that the palaeosols represent a period of increased humidity and landscape stability during late mis 7 and mis 6 hence in the agh band loess various changes in the palaeo sedimentary system triggered by changes in climate can be observed this yields important information on the sensitive response of sedimentary systems and landscapes within semi arid regions to shifts in moisture and possibly temperature

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

stable isotope data from loess malacofauna evidence for climate changes in the pannonian basin during the late pleistocene abstract loess is terrestrial clastic sediment composed dominantly of silt sized particles formed by the accumulation of wind blown dust it is usually inter bedded with palaeosol horizons forming loess palaeosol successions lps due to its characteristics loess represents a high quality record of climate changes in the late pleistocene the thickest and best studied loess sections in the republic of croatia are located in the eastern croatian province of baranja near the danube river this area is a southern part of the pannonian basin zmajevas lps was selected in this study grain size distribution indicates that the loess from zmajevac lps in baranja is typical loess comparable with other loess profiles in the pannonian basin the faunal assemblages in the loess samples prove the dominance of transitional palaeoecological assemblage types whereas uniformly defined types are rare helicopsis striata assemblage is dominant while columella columella and chondrula tridens assemblages are present in smaller proportion for additional information about palaeoclimate and palaeoecology in pannonian basin stable oxygen and carbon isotope ratios were measured in mollusc shells stable oxygen values range from 5 76 to 2 45 stable carbon isotope values range from 8 83 to 6 84 stable oxygen values show significant palaeotemperature changes during the late pleistocene with the average growing season ags temperature range of 13 24 c or 9 457 c depending on which formula is applied the overall climate was much cooler then present stable carbon isotope values point to dominance of c3 vegetation type during the late pleistocene in southern part of the pannonian basin

an approach to the problem of loess deposit formation some comments on the in situ or soil eluvial hypothesis abstract the problem of loess formation has been widely discussed for a long time and in many languages at the beginning of the 21st century some parts of this debate are still going on a case is still being made for the in situ approach and there are problems of terminology and mechanism for the central asian loess consideration of the origin of loess material has now replaced the discussion on deposit formation as the major intrinsic problem and in the world of ground engineering there is still much investigation on the origins of collapsibility which is in effect a discussion of loess origins there remain some interesting and useful observations to be made on the north african loess and the loess like materials in australia and the desert loess controversy is still running connections of loess to chernozems fragipans and rendzinas are becoming clearer and it seems that it may be possible to appreciate a loess landscape in which the loess contribution is not immediately apparent recent sem observations suggest that collapsibility develops after metastability as the in situ theory appears to imply

provenance of loess material and formation of loess deposits on the chinese loess plateau abstract results of a multiple isotopic chemical and mineralogical analysis of loess from the three northwestern inland basins the junggar basin the tarim basin and the qaidam basin and the loess plateau region of china are summarized they suggest a qualification of the conventional views that the three northwestern basins were the important source areas of the loess plateau and that the sand deserts were the primary single source of the chinese loess it is argued that the gobi stony desert in southern mongolia and the adjoining gobi and sand deserts the badain jaran desert tengger desert ulan buh desert hobq desert and mu us desert in china rather than the three inland basins are the dominant source areas of the loess plateau however although these gobi and sand deserts are regarded as the main source regions they serve as dust and silt holding areas rather than dominant producers the mountain processes including glacial grinding frost weathering salt weathering tectonic processes and some fluvial comminution in the gobi altay mts hangayn mts and the qilian mts have played an important role in producing the vast amounts of loess sized material for forming the loess plateau

loess is not just the accumulation of dust most regrettably there is much misuse of terminology in connection with the concept of loess and the interpretation of its origin people often speak and write incorrectly about loess accumulation even loess specialists who are aware of the fact that loess as a concept has to satisfy at least 10 criteria loess is not simply dust carried and deposited by wind dust only becomes loess after the passage of a certain amount of time in a given geographical zone i e only through diagenesis in certain ecological environments to state that loess is of aeolian origin is an oversimplification and an incorrect definition because an aeolian origin applies only to the dust from which the loess has been formed we are aware of the fact that airborne dust cannot be transformed into loess in every geographical environment but only under those conditions typical of semi arid grassland or steppe or forested steppe the process primarily occurs where the rate of dust accumulation exceeds sheet wash or weathering soil formation rates if the rate of dust accumulation is less than that of surface erosion or of soil biogenetic processes the dust then develops into soil or through intensive weathering and increased precipitation into loam or clay only part of the aeolian dust transported and deposited in a zone suitable for loess formation remains there permanently and is transformed in situ into loess dust not affected by diagenesis is usually further transported by snowmelt or rainwash and is only transformed into loess after it has been redeposited the loess itself however is easily erodible and its minerals are readily reworked and reaccumulated and given the appropriate conditions it readily undergoes diagenesis again we do not always have sufficient evidence to determine whether a given loess body is of primary or secondary origin traditionally the minerals making up primary loess have been regarded as originating in dust accumulated by aeolian processes secondary loess by contrast is different from typical loess in many ways and it is not unusual to find various loess series in which superimposed dust fractions have been transformed into loess by different processes recently we have observed that the origin of various types of loess is governed by differences in litho ecological conditions rather than by the way in which the mineral material from which the loess is derived dust has been primarily accumulated loessification is therefore determined by environmental conditions

characterisation of two fluvio lacustrine loessoid deposits on the island of gran canaria canary islands abstract the canary islands are close to the largest desert in the world the sahara and as a result the influence of air transported dust in the area is of great significance the present analysis consists of a study of two deposits in the ne and nw respectively of the island of gran canaria considered as fluvio lacustrine loessoids they exhibit the characteristics of aeolian deposits re worked by fluvial processes at the mouth of gullies and later edaphized in the nw profile galdar formed from 400 ka to present there are four different levels with abundant manganese stains over each and separated by dense calcrete laminations this sequence may be associated with cyclical processes of deposits in humid conditions and drying mn mobility plus the formation of arid soil carbonate precipitation the formation of the galdar profile took place between the upper pliocene and the upper pleistocene holocene the ne profile jinamar reveals a similar cyclic profile the jinamar fluvio loess deposit was formed between the upper pliocene and the upper pleistocene 1 96 0 1 ma the high percentage of the silt fraction 60 90 and the high percentage of quartz a mineral which is totally imported from the sahara desert are the main arguments in favour of the definition of these loess like deposits

pseudogleyed loess derivates the most common soil parent materials in the pannonian region of croatia abstract loess derived sediments represent the most widespread soil parent materials in the pannonian region of croatia pseudogley as the most common soil type in this region developed mainly on such parent materials pseudogleys largely correlate with the wrb reference soil group of stagnosols on the general soil map of croatia at scale 1 50 000 gsm of croatia the distinction is made between pleistocene loams pl and loess as pseudogley parent materials the initial purpose of this research was to investigate if the criteria for this distinction were clear and consistent and if the terms used for labeling these parent materials were adequate hence we investigated parent materials of 18 pseudogleys across 6 different locations three on loess and three on pl in the pannonian region of croatia we analyzed their morphology including micromorphology of three representative parent materials particle size distribution total porosity ph and mineral assemblages by modal analysis of three representative parent materials following these analyses no systematic differences between the loess parent materials and the pl parent materials were found additionally it was concluded that due to significant geogenetic and or pedogenetic alterations of all studied parent materials none of them should be labeled simply as loess hence parent material at one location was labeled as leached loess derivate and parent materials at all other locations were labeled as pseudogleyed loess derivates both types of parent materials were described in detail and defined in addition the terminology and the classification of loess derived parent materials in general was proposed the analyzed pseudogleyed loess derivates were not completely uniform across the investigated locations primarily this was due to the polygenesis of loess reflected by differences in particle size distributions and compositions of light and heavy mineral fractions secondarily it was due to the 600 1100 mm map gradient along the study region reflected by differences in ph values and properties of redoximorphic features although pedogenesis of the investigated parent materials might have started already during the late glacial and have continued throughout the holocene at varying and overall decreasing rates their morphology indicates that pseudogleization and lessivage are still active processes which occur simultaneously in the analyzed parent materials and agree with the present climate

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

misleading positions of geomagnetic reversal boundaries in eurasian loess and implications for correlation between continental and marine sedimentary sequences abstract the matuyama brunhes boundary mbb where the earth s magnetic field changed to its present orientation is one of the most frequently used time markers in continental quaternary stratigraphy although magnetic signals have been successfully recovered from loess deposits and an apparently coherent magnetostratigraphy seems to be in place a close examination of the published loess records from northern mid latitudes reveals significant uncertainty and variability for the position of the mbb in asia and part of central europe the mbb has been found in loess a glacial deposit this is in contrast to the well established palaeomagnetic records in deep sea sediments where the mbb is located in the interglacial oxygen isotope stage 19 this discrepancy has caused serious confusion in stratigraphic correlation between loess and marine sequences here we examine the causes of the discrepancy between the two sedimentary environments in their records of the mbb our approach includes a comparison of the mbb in loess and other continental records and an evaluation of the stratigraphic significance of the microtektites found around the mbb based on the occurrence of the mbb in an interglacial stage in lake and continental margin sequences and the correlative stratigraphic positions of the microtektites in marine sediments and loess we demonstrate that the measured positions of the mbb in loess are erroneous and misleading and its true occurrence was during the time of formation of the palaeosol corresponding to oxygen isotope stage 19 the most plausible cause for the apparent offset i e the mbb being found in the underlying loess instead is that the acquisition of remanent magnetisation in loess occurs at a certain depth substantially below the land surface the degree of such displacement is dependent on the lithology and structure of the deposits formed prior to the reversal and the time delay is estimated to be in the order of 103 104 years we show that other geomagnetic boundaries such as those of jaramillo and cobb mountain in loess have been similarly displaced though to a varying extent we suggest that the remanence acquisition in loess is closely related to the post depositional evolution in the structure of loessic materials which is in part influenced by regional climate conditions our conclusions on the displaced remanence acquisition have implications for loess chronology magnetostratigraphy as well as the geomagnetic interpretation of detailed magnetic signatures from loess

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

pleistocene environmental dynamics recorded in the loess of the middle and lower danube basin abstract the substantial loess deposits of the middle and lower danube basin in southeastern europe represent one of the thickest and most comprehensive terrestrial palaeoenvironmental records on the continent yet are also the least well understood environmental conditions over the last million years have resulted in relatively continuous deposits uninterrupted by glaciation and tundra conditions which nevertheless reflect oscillations between relatively warm humid interglacial and cold dry glacial intervals this relative environmental stability may have proven important for hominins migrating into and through the region the loess stratigraphy comprises distinct loess paleosol sequences reflecting glacial interglacial phases which can be quantified for intensity using environmental magnetism and geochemistry these phases are emphasised by variations in vegetation and malacofauna which respond to climatic change the loess deposits demonstrate broadly similar sedimentological characteristics across the basin danubian loess deposits initiated in response to the tectonic formation of the pannonian basin retreat of the large palaeolakes and increased sediment supply from the danube the period from 1 ma 500 ka mis 27 13 was characterised by alternating loess deposition and pedogenesis during glacial and interglacial periods respectively in response to relatively humid forested conditions this period represents the opening of the danube corridor and provides the backdrop for initial hominin arrival into europe after 500 ka and particularly after mis 9 loess accumulation rates increased in response to relatively more steppic arid environments mis 9 and 13 15 were the most humid phases of the last 600 ky the mis 5 interglacial period was the warmest and relatively most humid period preceding the holocene and was followed by substantially increased loess accumulation during mis 4 which may be linked to north atlantic circulation the complexity of the mis 3 interstadial paleosol suggests that conditions were not uniformly warm and wet during this time mis 3 corresponds with the first arrival of anatomically modern humans to europe the last glacial maximum and younger dryas of mis 2 were characterised by substantially increased loess accumulation indicating cold steppe environments most likely influenced by the north atlantic although conditions were sufficiently mild that the region acted as a refugium for thermophilic biota as may also have been the case for most of the pleistocene glacial cycles the holocene soil represents relatively wamer and more humid conditions corresponding to the current interglacial

amino acid geochronology applied to the correlation and dating of central european loess deposits abstract numerous localities in the czech republic slovakia and austria have been sampled for fossil gastropod shells for the purpose of an aminostratigraphic evaluation of loess sequences in all three regions alloisoleucine isoleucine aile ile ratios are observed to be significantly higher in shells from loess deposited during the penultimate glacial period cycle c relative to samples from loess of the last glaciation cycle b the difference in aile ile ratio reflects both difference in age of the samples plus the impact on the older samples of the relatively high effective temperature of the last interglacial period amino acid data support the previous correlation suggested between pk ii iii in the czech republic and slovakia and the stillfried a in austria samples have also been recovered from older loess units and previously published correlations within the czech and slovak republics are tested aiie ile ratios appear to distinguish between samples from loess of the last four glacial cycles beyond cycle e 18o stages 10 and 11 the increase in alle ile ratio is relatively small from cycle to cycle in addition shells tend to be poorly preserved and are absent at many localities nevertheless amino acid geochronology offers a means of resolving ages of loess units in the critical time period that is beyond the range of radiocarbon and thermoluminescence methods but post dates the brunhes matuyama paleomagnetic reversal

the loess deposits of buca dei corvi section central italy revisited loess deposits have been described in the past for the upper section of buca dei corvi succession central italy in this paper the deposits were re analysed to clarify the depositional environment and to attempt a paleoclimate reconstruction two radiocarbon dates on pedogenic carbonate constrain the ages to the late glacial and are consistent with previous osl dating of the top of the succession the non marine mollusc assemblage shows typical character of cold and dry climatic conditions testified by strong oligotypical composition mineralogy and geochemistry of the sediments indicate the abundant presence of exotic quartz mineral which can be explained only by wind transport probably wind transport was also responsible of deposition of carbonate which then dissolved and re precipitated producing pedogenic concretions stable isotopes 13c 12c and 18o 16o ratios of the concretions are consistent with a climate drier than present conditions with an environment characterized by sparse vegetation

permafrost or seasonal frost a review of paleoclimate proxies of the last glacial cycle in the east central european lowlands abstract our critical revision of the sedimentological characteristics and genetic interpretation of relict periglacial soil deformation features cryoturbations and sand wedges suggests that the continuous permafrost zone did not necessarily reached the lowland areas of the pannonian basin as suggested by previous studies the discontinuous permafrost zone most probably penetrated the north western part of the study area for a certain period but most of the lowlands might have been affected only by sporadic isolated permafrost and or deep seasonal frost the re evaluated climate conditions implied by the periglacial soil structures and other proxies for a periglacial environment of the area do not constrain such a narrow zone of extremely low mean annual air temperature maat and mean annual precipitation map the compilation of the climate thresholds suggested by the observed and revised interpretation cryoturbation features and thermal contraction cracks with other paleoclimate proxies converge on 0 2 c maat and 300 490 mm map on the lowland areas of the pannonian basin during the coldest phase of the last glacial these values indicate a temperature drop of 10 2 c and a precipitation decrease of 30 50 relative to modern conditions

holocene soils and sediments around ma rib oasis yemen further sabaean treasures the ancient cultures of southern arabia are increasingly recognised as playing as major a role in the heritage of mankind as the early cultures of egypt mesopotamia or the indus valley the beginning of the widely known sabaean culture dates back to the end of the second millennium bc whereas undoubtedly its wealth came mainly from the trade along the incense road the backbone of its economy was irrigated agriculture since agriculture is based on soil and water resources and hence land availability the buried soils and sediments of the area surrounding the ma rib oasis have been investigated both as an archive of holocene soil development in pre sabaean times and as natural treasures as for example ores or alabaster are defined the natural buried holocene soils around ma rib are rich in phosphate organic material and volcanic ashes in a few places they demonstrate cultivation before the great dam of ma rib was built in the first millennium bc most important are those soils that formed d

the mis 3 2 transition in a new loess profile at krems wachtberg east a multi methodological approach abstract local to regional paleoenvironmental reactions to past climate changes are preserved in loess paleosol sequences lps in order to extract this information we used a multi methodological approach in the upper paleolithic site of krems wachtberg east in lower austria detailed field studies and high resolution geochemical colorimetric and granulometric analyses help to understand the interplay between soil formation loess accumulation and surface processes in comparison to the main profile excavation of krems wachtberg 2005 2015 it can be stated that osl and 14c ages as well as the archeological stratigraphy of both profiles are comparable however pedogenic features are more evident at krems wachtberg east the new investigations show that well established weathering indices do not clearly trace interstadial soil formation in the studied profile apart from this fact single specific elements like fe and mg react more sensitive to initial pedogenic processes weak pedogenesis can further be evidenced by quantitative spectrophotometric results the latter is also capable of refining and supporting the stratigraphy pedology based on field analyses as a general rule next to loess also initial soil horizons of the mis 3 are remarkably rich in primary carbonates indicating that soil formation took place in an alkaline environment due to the fact that hydrolysis of feldspars could not clearly be detected by the application of pedochemical indices soil formation was probably limited to the oxidation of iron bearing minerals and weak carbonate leaching these phases of favorable climatic conditions in terms of pedogenesis were terminated by increasing dust input towards the onset of mis 2 the eolian deposits are overprinted during reducing conditions in soils and or modified by colluvial processes altogether weak pedogenesis can be reliably detected using a multi methodological approach which leads to enhanced paleoenvironmental interpretations the osl ages put the profile in a range of 41 to 30 ka we present a tentative correlation of the studied loess profile to the record of the north greenland ice core project ngrip for the part of the profile where osl and 14c complement each other

danube loess stratigraphy towards a pan european loess stratigraphic model abstract the danube river drainage basin is the second largest river catchment in europe and contains a significant and extensive region of thick loess deposits that preserve a record of a wide variety of recent and past environments indeed the danube river and tributaries may themselves be responsible for the transportation of large volumes of silt that ultimately drive loess formation in the middle and lower reaches of this large catchment however this vast loess province lacks a unified stratigraphic scheme european loess research started in the late 17th century in the danube basin with the work of count luigi ferdinand marsigli since that time numerous investigations provided the basis for the pioneering stratigraphic framework proposed initially by kukla 1970 1977 in his correlations of loess with deep sea sediments loess palaeosol sequences in the middle and lower reaches of the danube river basin were a key part of this framework and contain some of the longest and most complete continental climate records in europe covering more than the last million years however the very size of the danube loess belt and the large number of countries it covers presents a major limiting factor in developing a unified approach that enables continental scale analysis of the deposits local loess palaeosol stratigraphic schemes have been defined separately in different countries and the difficulties in correlating such schemes which often change significantly with advances in age dating have limited the number of basin wide studies a unified basin wide stratigraphic model would greatly alleviate these difficulties and facilitate research into the wider significance of these loess records therefore we review the existing stratigraphic schemes and define a new danube basin wide loess stratigraphy based around a synthetic type section of the mosorin and stari slankamen sites in serbia we present a detailed comparison with the sedimentological and palaeoclimatic records preserved in sediments of the chinese loess plateau with the oxygen isotope records from deep sea sediments and with classic european pleistocene stratigraphic subdivisions the hierarchy of danubian stratigraphic units is determined by climatically controlled environmental shifts in a similar way to the chinese loess stratigraphic scheme a new unified danube loess stratigraphic model has a number of advantages including preventing confusion resulting from the use of multiple national schemes a more transparent basis and the potential to set pleistocene palaeoenvironmental changes recorded in the danube catchment area into a global context the use of a very simple labelling system based on the well established chinese loess scheme facilitates interpretation of palaeoenvironmental information reported from the danube basin loess sites in a wider more accessible context that can be readily correlated world wide this stratigraphic approach also provides for the first time an appropriate framework for the development of an integrated pan european and potentially pan eurasian loess stratigraphic scheme

loess studies in central united states evolution of concepts abstract few words in the realm of earth science have caused more debate than loess it is a common term that was first used as a name of a silt deposit before it was defined in a scientific sense because this loose deposit is easily distinguished from other more coherent deposits it was recognized as a matter of practical concern and later became the object of much scientific scrutiny loess was first recognized along the rhine valley in germany in the 1830s and was first noted in the united states in 1846 along the lower mississippi river where it later became the center of attention the use of the name eventually spread around the world but its use has not been consistently applied over the years some interpretations and stratigraphy correlations have been validated but others have been hotly contested on conceptual grounds and semantic issues the concept of loess evolved into a complex issue as loess and loess like deposits were discovered in different parts of the us the evolution of concepts in the central us developed in four indefinite stages the eras of 1 discovery and development of hypotheses 2 conditional acceptance of the eolian origin of loess 3 bandwagon popularity of loess research and 4 analytical inquiry on the nature of loess toward the end of the first era around 1900 the popular opinion on the meaning of the term loess shifted from a lithological sense of loose silt to a lithogenetic sense of eolian silt however the dual use of the term fostered a lingering skepticism during the second era that ended in 1944 with an explosion of interest that lasted for more than a decade in 1944 r j russell proposed and h n fisk defended a new non eolian property based concept of loess the eolian advocates reacted with surprise and enthusiasm each side used constrained arguments to show their view of the problem but did not examine the fundamental problem which was not in the proofs of their hypothesis but in the definition of the term between 1944 and about 1950 the debates about loess reached a maximum level of complexity the main semantic problem was submersed in peripheral arguments about physical properties and genetic interpretations the scholarly treatment of the subject by fisk and russell stimulated quality responses from a diversity of earth scientists interested in academic and applied studies particularly geo history pedology soil mechanics and stratigraphy the long lasting popularity of loess studies during the bandwagon era lasted to about 1970 by that time the analytical and technical interests had attracted the mainstream into the fourth era with a focus beyond the old arguments although fisk and russell found themselves defending an unpopular theory they stimulated a scientific interest in the late quaternary history of the mississippi valley that may never be exceeded

wetting driven formation of present day loess structure abstract present day loess especially malan loess formed in later quaternary has a characteristic structure composed of vertically aligned strong units and weak segments hypotheses describing how this structure forms inside original loess deposits commonly relate it to wetting drying process we tested this causal relationship by conducting unique experiments on synthetic samples of initial loess deposits fabricated by free fall of loess particles these samples were subjected to a wetting drying cycle and their structural evolutions were documented by close up photography and ct scanning analysis of these records revealed three key stages of structural evolution initiation evenly distributed cracks appear due to wetting inhomogeneitization some cracks grow forming large polygons and development polygon forming cracks grow further cracks within polygons narrow down or heal up these experiments successfully reproduced the characteristic structure of present day loess and led to a discovery that it is the wetting of initial loess that initiates and drives the structural evolution while drying preserves and expands resulting features

micromechanics of quartz sand breakage in a fractal context from a quaternary science perspective sand sized quartz as well as silt sized quartz is often acknowledged as final products of glacial abrasion through different evolution mechanisms this view challenges the existence of any universal comminution process which may relate the formation of detrital quartz sand and silt the contribution of grain size energy input and crystalline integrity in the scale of quartz crushability has long been the matter of much debate the present empirical work examines the micromechanics of sand to silt size reduction in the quartz material a series of grinding experiments was performed on leighton buzzard lower greensand using a high energy agate disc mill analogous conditions to glacial abrasion are provided due to the combined abrasion between grains asperity tips and also between grains and rotating smooth tungsten carbide pestle simulation of discontinuous grain breakage allowed the examination of grains crystalline defects to enable an objective assessment of micromechanics of size reduction measurements of particle and mode size distribution fractal indexes and micro morphological signatures were made the crushing approach was probed through varied grinding times at a constant energy input as well as varied energy inputs at constant grinding time breakage pathway was inspected via laser diffraction spectroscopy and transmission light microscopy results suggested that the grain breakdown is not necessarily an energy dependent process non crystallographically pure amorphous quartz sand and silt are inherently breakable materials through a fractal breakdown process results also revealed that the internal defects in quartz are independent from size and energy input

granulometrical mineralogical and geochemical characterization of loess deposits in the tajo basin abstract loess research has the merit of enabling reconstructions of pleistocene sedimentation dynamics in many parts of the world however there is still very few information regarding the occurrence of loess deposits in the mediterranean area even though such records may provide a unique opportunity to investigate landscape evolution for a period for which terrestrial archives are very rare in this region this paper presents the first results of investigations on a loess sequence in the middle tajo valley in central spain findings from detailed granulometrical mineralogical geochemical and grain morphological analyses help to give a first overview on character and composition of these deposits very high levels of carbonates 60 but also of gypsum both to large extents of primary origin indicate the incorporation of material derived from marls and limestone furthermore we found evidence that allows deduction of possible loess proveniences more precisely dolomite contents of up to 20 indicate that the iberian range might have been an important source area of loess sediments the fact that these uplands are located to the east seems to be opposed to the common assumption of prevailing west winds for glacial periods the studied sequence paraiso profile is one of seven sections that have been investigated as part of a programme to reconstruct upper pleistocene landscape dynamics in central spain in this context the detailed characterisation of sediment properties is crucial for discussing loess proveniences and sedimentary environments

origin weathering and geochemical composition of loess in southwestern hungary abstract loess geochemistry generally reflects paleo weathering conditions and it can be used to determine the average composition of the upper continental crust ucc in this study major and trace element concentrations were analyzed on loess samples from southwestern hungary to determine the factors influencing their chemical compositions and to propose new average loess compositions all studied loess samples had nearly uniform chemical composition suggesting similar alteration history of these deposits chemical index of alteration values 58 69 suggested a weak to moderate degree of weathering in a felsic source area typical non steady state weathering conditions were shown on the al 2 o 3 cao na 2 o k 2 o patterns indicating active tectonism of the alpine carpathian system during the pleistocene whole rock element budgets were controlled by heavy minerals derived from a felsic magmatic or reworked sedimentary provenance geochemical parameters indicated that dust particles must have been recycled and well homogenized during fluvial and eolian transport processes

marker horizons in the loesses of the carpathian basin abstract two tephra horizons are known in the middle and upper pleistocene loesses of the carpathian basin the older bag tephra has been described from numerous loess outcrops in hungary whereas the younger paks tephra has been described only from the brickyard of paks in southern hungary the most characteristic heavy minerals in these horizons are various clinopyroxenes occurring in different proportions the clinopyroxenes of the bag tephra are extremely rich in ca and al while the volcanic glass is rich in k indicating high k andesitic or shoshonitic volcanism based on comparative geochemical analyses the most likely origin of the bag tephra is the roman or the campanian volcanic fields in italy geochemical investigation of the paks tephra is in progress and preliminary results suggest the same source for this younger tephra in contrast to the tephra horizons the correlation of the numerous paleosols in some hungarian loess sections and their paleoenvironmental interpretation is possible only if they are based on very detailed micromorphological studies the age determination of the loesses containing the paleosols directly by thermoluminescence tl and infrared stimulated luminescence irsl and indirectly by 14 c based isotope work should provide a reliable basis for the identification of soil forming periods in different parts of the carpathian basin

new chronology of the best developed loess paleosol sequence of hungary capturing the past 1 1 ma implications for correlation and proposed pan eurasian stratigraphic schemes abstract in this paper we are presenting a revised chronology of the best developed longest 100 m lps in hungary dating back 1 1 ma borehole udvari 2a it is based on a non tuned age depth model built on the position of the matuyama brunhes boundary jaramillo and olduvai subchrons furthermore on the assignment of formerly recorded uninterpreted geomagnetic reversals in both chrons other chronometric tools ams 14c dating biostratigraphy tephrostratigraphy yielding absolute ages and or ensuring validation of these were also used records of a middle pleistocene gastropod index fossil neostyriaca corynodes 400 140 ka facilitated verification of ages between mis 10 and mis 6 multiple age control points at 15 25 27 45 120 191 362 430 670 780 900 990 1070 ka were established for the last ca 1 1 ma the resulting chronology is the best resolved independent one so far among danubian basin lpss in light of our data the s3 s4 units were fused as s3 in all serbian and some romanian sites and re correlated with mis 9 the results also point to a misassignment of the s5 units at these sites to mis 13 15 leading to erroneous conclusions regarding paleoclimatic conditions and cyclicity in our new stratigraphic scheme these s5 paleosols were taken to represent the s4 paleosol and recorrelated with mis 11 finally an ideal stratigraphic column dating back 1 1 ma for sw hungary was constructed and correlated with the chinese loess paleosol sequence of xifeng and the benthic oxygen isotope record down to mis 31

a review on the lithospheric structures in the tibetan plateau and constraints for dynamics in the last decade several international joint projects were conducted in the tibetan plateau by chinese american and french geophysicists and geologists in the present review the results from vertical reflections wide angle reflections and broadband digital seismic recordings are reviewed and compared constraints for the dynamics of continent continent collision from the lithospheric structures seismicity focal mechanism and anisotropy are discussed

loess is almost totally formed by the accumulation of dust in 1990 marton pecsi published a paper entitled loess is not just the accumulation of dust this 1990 paper presented the case for considering aspects of loess formation other than the aeolian deposition of silty material pecsi argued that there is more to loess formation than simply the fact of aeolian deposition while not disputing the validity of much of pecsi s arguments a case can be made for considering that aeolian deposition is at the very heart of loess formation that the factor of aeolian deposition is so critical that other aspects are relatively unimportant pecsi appeared to suggest that aeolian deposition is just one of many factors relating to the formation of loess deposits this is not so aeolian deposition and the consequent formation of metastable structures is absolutely central but it is probably useful to consider the aeolian deposition is absolutely critical approach and the aeolian deposition is one of the factors approach in some more detail and in relation to each other some insights may accrue interesting things do happen after the deposition of the dust and this needs to be acknowledged

high resolution record of the last interglacial glacial cycle in the nussloch loess palaeosol sequences upper rhine area germany the nussloch loess sequences were sampled at close intervals 10 cm and documented in respect of their stratigraphy palaeopedology sedimentology palynology malacology and geochemistry and were dated using radiocarbon and osl methods for each stratigraphic unit the results of both the eld studies and the analytical and geochronological data obtained cast light upon the response of the loessic environment to global climatic variations during the last cycle the basal soil complex underwent a pedosedimentary evolution similar to those of the bordering area complex luvisol greyzem steppe soila which re ects the classic progression towards increased continentality of the environment between the end of the eemian 5d and the beginning of the full glacial stage pleniglacial the lower pleniglacial corresponds to an initially very arid phase dominated by the accumulation of loess followed by the deposition of strati ed niveo eolian sands the middle pleniglacial complex ca 55 30 is clearly characterised by the inhibited loessic sedimentation it is primarily marked by two phases of stabilisation recorded in the form of weathered horizons cambisols which are separated by a rather thin layer corresponding to loessic sedimentation with tundra gleys this intermediate phase brings together organic silt deposits which record an interstadial dated at 32 33 ka c bp the thick loessic accumulations of the upper pleniglacial 10 m which clearly began to accumulate before the oxygen isotope stage ois 3 2 boundary show evidence of vulnerability to considerable uctuations in response to variations in wind dynamics and the intensity of de ation in the rhine valley finally a proposed correlation of loess palaeosol stratigraphies from germany belgium and france spanning the entire last interglacial glacial cycle is presented 2001 elsevier science ltd and inqua all rights reserved

deep yedoma permafrost a synthesis of depositional characteristics and carbon vulnerability abstract permafrost is a distinct feature of the terrestrial arctic and is vulnerable to climate warming permafrost degrades in different ways including deepening of a seasonally unfrozen surface and localized but rapid development of deep thaw features pleistocene ice rich permafrost with syngenetic ice wedges termed yedoma deposits are widespread in siberia alaska and yukon canada and may be especially prone to rapid thaw processes freeze locked organic matter in such deposits can be re mobilized on short time scales and contribute to a carbon cycle climate feedback here we synthesize the characteristics and vulnerability of yedoma deposits by synthesizing studies on the yedoma origin and the associated organic carbon pool we suggest that yedoma deposits accumulated under periglacial weathering transport and deposition dynamics in non glaciated regions during the late pleistocene until the beginning of late glacial warming the deposits formed due to a combination of aeolian colluvial nival and alluvial deposition and simultaneous ground ice accumulation we found up to 130 gigatons organic carbon in yedoma parts of which are well preserved and available for fast decomposition after thaw based on incubation experiments up to 10 of the yedoma carbon is considered especially decomposable and may be released upon thaw the substantial amount of ground ice in yedoma makes it highly vulnerable to disturbances such as thermokarst and thermo erosion processes mobilization of permafrost carbon is expected to increase under future climate warming our synthesis results underline the need of accounting for yedoma carbon stocks in next generation earth system models for a more complete representation of the permafrost carbon feedback

late pleistocene loess palaeosol sequences in the vojvodina region north serbia late pleistocene loess palaeosol sequences are widespread in the vojvodina region with thicknesses reaching a maximum of about 20 m our investigations include more than 40 of these loess sections geochronology of the last glacial loess palaeosol sequences based on lumines cence dating and amino acid racemisation provides correlations between upper pleistocene loess palaeosol sediments in vojvodina and comparable deposits at other european localities sedimentary logs of magnetic susceptibility grain size measurements and carbonate content combined with malacological evidence indicate two main relatively cold and arid phases during the last glacial period related to intensive accumulation of loess units l1l1 and l1l2 as well as many brief episodes of dry and windy climatic conditions suggesting a possible relationship with cold events recorded in the north atlantic region generally late pleistocene climate in the region was dry and relatively warm compared with glacial period sites in central europe and was characterised by sharp differences between glacial and interglacial modes new data and interpretations presented in this study emphasise the significance of loess palaeosol sequences in vojvodina for the reconstruction of the temporal and spatial evolution of late pleistocene palaeoclimate in this part of europe copyright 2007 john wiley sons ltd

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

a multi proxy analysis of two loess paleosol sequences in the northern harz foreland germany two loess paleosol sequences from the northern harz foreland hecklingen and zilly have been investigated in general loess paleosol sequences represent valuable terrestrial archives of regional environmental and climatic conditions during past glacial periods the study area is part of the northern european loess belt and was in the vicinity of the scandinavian ice sheet during the weichselian aiming towards a better understanding of the paleoenvironmental conditions during the weichselian in an area close to the scandinavian ice sheet results from grain size geochemical xrf cns color and magnetic susceptibility measurements are combined the findings demonstrate an increased input of aeolian material during the last glacial maximum and the last cover loess period which is in accordance to the theory of drier and colder conditions during this time frame further data reveal a strong input not only of loess but also of coarser material coming from a shorter distance during the last glacial maximum in both profiles material of the last glacial maximum clearly indicates a shift of wind direction towards easterly winds in hecklingen an enhancement of coarser material has been observed within the recent soil and mis 3 soil material since soil material that dates back to the mis 3 is present in the profile it can be assumed that surface processes were less intrusive during the mis 3 and 2 than in e g the lower rhine embayment and saxony c 2016 elsevier b v all rights reserved

discovery of a landscape wide drape of late glacial aeolian silt in the western northern calcareous alps austria first results and implications abstract aeolian deposits record palaeoenvironmental conditions and may coin soil properties whereas periglacial loess is extensively investigated for 200 years the study of the intramontane wind blown deposits of the alps has just stuttered along herein we describe a drape of polymictic siliciclastic silt interpreted as an aeolian deposit that veneers extensive areas in the western northern calcareous alps nca from kames terraces near valley floors up to last glacial nunataks the nca part of the eastern alps mountain range consist mainly of triassic carbonate rocks these are overlain by deposits of the last glacial maximum lgm and its deglacial paraglacial aftermath e g glacial tills fluvio lacustrine successions alluvial fans scree slopes and a regional drape of polymictic silt newly described herein the drape is typically a few decimeters in thickness and slightly modified by soil formation it consists mainly of well sorted silt of quartz feldspars phyllosilicates muscovite chlorite biotite amphiboles and rarely calcite or dolomite the drape is unrelated to the substrate it overlies carbonate bedrock and in lateral continuity abandoned deposystems such as colluvial slopes of redeposited till kames alluvial fans scree slopes and rock avalanche deposits the drape was spotted from near the present valley floors up to lgm nunataks over a vertical range of some 2000 m it is also present in catchments of the nca that were not overridden by far travelled ice streams and that lack metamorphic rock fragments two osl quartz ages of the drape from two distinct locations 18 77 1 55 ka 17 81 1 68 ka fall into the early alpine late glacial interval shortly after the collapse of pleniglacial ice streams this fits with geological and geomorphological evidence respectively that the drape should be of early late glacial age and that it accumulated during a specific interval of time in the nca localized minor deposition of aeolian dust is documented by other authors from plateaus deglaciated only during the late glacial to holocene no evidence however exists for another phase of similarly widespread aeolian deposition such as that which gave rise to the described regional drape of silt intense aeolian transport and deposition was probably a direct consequence of the liberation of huge amounts of unsorted sediment during deglacial ice collapse perhaps combined with climatic aridification this provides a hitherto unappreciated element of the deglacial to paraglacial phase intramontane dust storms because of its large extent and the availability to osl dating the aeolian drape provides an excellent geochronological marker level identified in terrestrial post glacial successions of the eastern alps because of its fine grained siliciclastic composition the drape gives rise to widespread development of atypical cambisols on carbonate bedrocks with comparatively high water storage capacity and nutrient supply

the loess profile at albertirsa hungary improvements in loess stratigraphy by luminescence dating abstract a very detailed upper pleistocene record is exposed in a loess palaeosol sequence at the section at albertirsa in hungary luminescence dating was carried out to establish a more reliable chronological framework for the hungarian loess record the lowermost palaeosol of the section probably an equivalent of the mf2 horizon at the mende key section is superimposed on penultimate glacial loess an irsl age estimate of about 65 ka bp was determined for the lower part of this palaeosol indicating soil formation late in oxygen isotope stage ois 5 or early in ois 3 a significant hiatus most likely occurs in the lower part of the lower fossil soil the loess between the upper and and lower palaeosol yielded a mean luminescence age of about 50 ka bp the upper palaeosol is probably an equivalent of the mf1 horizon at the mende type section formed between 37 and 25 ka bp and so this palaeosol represents the hengelo and or denekamp interstadial of northwestern european stratigraphy the loess is intercalated by a humic horizon which yielded a mean luminescence age estimate between 21 and 19 ka at the albertirsa section

loess soil sequence at toshan northern iran insights into late pleistocene climate change abstract the knowledge of palaeoclimate in iran is still limited however insight into the timing and the dynamics of quaternary climate change in iran might offer valuable information to improve the global palaeoclimate record the loess soil sequence of toshan provides the first high resolution record of late pleistocene climate dynamics in iran and complements the hitherto known sections at neka now deh and agh band to establish a pedostratigraphic record of the north eastern caspian lowland our spectroscopic and grain size analysis are combined to propose i a pedostratigraphical scheme for the sequence at toshan ii describe and estimate the degree of soil development of selected stratigraphical units iii infer palaeoclimatic information and provide iv a correlation with previous loess palaeosol records of n iran as based on pedostratigraphic assumptions the section at toshan hosts a strongly developed reddish brown argillic palaeosol bt as well as eight moderately to weakly developed brownish palaeosol horizons lacking clay illuviation features bw bwk these remnants of fossil soils are separated by finely textured loess and horizons that host characteristics of both loess and mineral subsoils cb cbk giving evidence for syngenetic soil formation the stratigraphical succession of palaeosols loess and syngenetically altered sediments covering the last ca 130 ka gives evidence for recurrent climate changes as well as fluctuations between dominance of soil formation or dust accumulation in relation to changes in moisture regime the formation of bt and bw bwk horizons is related to relatively humid and warm conditions likely corresponding with interglacial and interstadial climate

magnetic properties of loess grain size fractions from the section at paks hungary abstract the approximately 50 m thick loess palaeosol sequence at paks brickyard hungary was deposited largely during the brunhes normal polarity chron and its magnetic properties resemble those of similar sections in europe central asia and china in order to get information on the grain size dependence of some of the magnetic parameters two loess and two palaeosol samples were separated into a number of grain size fractions the separation method employs consecutive sedimentation and centrifugation steps performed on bulk samples suspended in water and diluted with calgon ten grain size fractions were obtained ranging from 50 m down to 10 nm several magnetic parameters of the different grain size fractions have been measured at room temperature low field susceptibility hysteresis parameters and at low temperature susceptibility and thermoremanent magnetisation they show a strong grain size dependence for the ferromagnetic minerals low temperature measurements allow discrimination of the paramagnetic vs the ferromagnetic signal and give information on the grain size distribution of the very fine ferromagnetic minerals and on the mineral types carrying the magnetic signal strong relationships between weathering processes destruction of paramagnetic minerals and possibly iron hydroxides and enhancement of the ferromagnetic signal are observed

likhvin interglacial polygenetic paleosol a reconstruction on the russian plain abstract one of the most important quaternary terrestrial climatic proxy records is the loess paleosol sequence found in the russian plain of eastern europe along the plain the likhvin interglacial corresponds to the two phase inzhavino polygenetic paleosol ipp known as an analog of the holsteinian interglacial the objectives of this study are 1 to present new information supporting the ipp genesis and its stratigraphic correlation in the central russian plain and 2 to evaluate soil zonation for the two phases of the ipp development for the first time geographic zonality and shifts of soil zones are described for the two phases of the ipp the older interglacial optimum phase of the ipp phase a features changes from north to south as does the modern day soil in the same geographical area although soil zones of the optimum are shifted slightly southward relative to present day soil zones albeluvisols reconstructed on the north of the study area develop into cambisols luvisols phaeozems in the central part of the area and into chernozems further southward it appears that climatic conditions during paleosol formation were more humid than at present the younger post optimal phase of the ipp phase b is identified as an accretionary humic regosol on the central russian plain but developed into chernozems southward the phase b soil zonation is simplified in comparison with present day one and tentatively corresponds to interstadial conditions therefore spatial changes in the ipp features indicate that zonal structure of environment developed along the russian plain at least as early as the middle pleistocene likhvin interglacial

magnetic granulometric and geochemical characterizations of loess sections in the eastern arid central asia implication for paleoenvironmental interpretations abstract loess deposits in the arid central asia aca contain sensitive messages concerning the evolution of the westerlies and the interior aridification of asia in this study we conducted a combined study of geophysical and geochemical characterization on loess sections in the eastern aca to discuss possible paleoclimate development since the late pleistocene era results show that the aca loess chiefly exhibited similar geophysical and geochemical compositions with loess deposits in other regions like the chinese loess plateau there are various accumulation rates that would have been responsible for the depositional difference within the aca loess profiles in addition there are three magnetic responses to the bulk grains and geochemical proxies in this study at the bottom segment of the section magnetic enhancement was associated with coarse grain sizes and water leaching magnetic enhancement responded to stronger pedogenesis and moderate paleo wind intensity in the uppermost parts moreover there is a transitional segment in the middle part of the section characterized by inordinately detrital inputs and weak pedogenic contributions thus it may be better to evaluate the magnetic climatology of the aca loess through different depositional stages furthermore this study generally reveals that the paleoclimate pattern in the aca was probably characterized by relatively low moisture during warm intervals and vice versa in the middle and bottom parts of the profiles but relatively enhanced moisture was indicated during the holocene period further studies are still necessary to obtain reliable proxies and chronology for a detailed paleoclimate interpretation of the aca loess

a critical reevaluation of palaeoclimate proxy records from loess in the carpathian basin abstract in the carpathian basin loess is the most important archive of quaternary palaeoclimate evolution but only in the past two decades systematic and high resolution investigations were conducted those studies remarkably improved our knowledge of the regional past environmental change palaeoclimate inferences based on the magnetic susceptibility and grain size distribution as the most commonly used palaeoenvironmental proxies for the carpathian basin loess indicate colder and drier climatic conditions during glacials when compared to interglacials with an increasing number of studies using novel proxies in loess research such a traditional understanding of dry and cold glacials and humid and warm interglacials in the carpathian basin has been questioned as an illustrative example mollusc based climate reconstructions suggest generally warm and very dry summer conditions with mean july temperatures up to 21 c for the southern carpathian basin during the last glacial results based on stable carbon isotopes strongly oppose such high summer temperatures but studies based on n alkanes are in general agreement with the mollusc data when it comes to the vegetation reconstruction indicating mostly steppic conditions however n alkanes studies contradict warm and dry glacial conditions as indicated by mollusc based reconstructions pointing instead to cold and relatively humid glacials in addition there is an ongoing debate whether or not millennial scale climatic oscillations can be observed in the carpathian basin loess as well as whether this area was an important northern hemisphere dust source or rather a sink of far distance dust transport consequently the current state of the art of the palaeoclimate reconstructions from loess in the carpathian basin is rather inconsistent in order to make sense of the existing palaeoclimate data from the carpathian basin loess we have reevaluated and reinterpreted the available data we discuss and propose a coherent interpretation of rock magnetic grain size malacological stable carbon and nitrogen isotope n alkane and bacterial membrane lipid data for the last glacial cycle loess archives from the carpathian basin we show that glacial conditions in the carpathian basin led to a notable increasing north south gradient in temperature and an even stronger expressed decreasing trend in humidity and that most of the biomarker proxy data conducted in loess for the very dry southern part of the carpathian basin show a strong bias towards arid conditions in particular palaeotemperature reconstructions seem to be misleading glacial conditions were drier and colder than previously proposed summer temperatures likely under 15 c during glacials but notably warmer than in other parts of western central and eastern europe the vegetation consisted mostly of steppic environments during both glacials and interglacials we indicate that the carpathian basin has a potential to be a major dust source of the northern hemisphere during glacials although it was at the same time exposed to the deposition of fine far distance travelled dust moreover the main issues in the regional and continental correlation of loess are highlighted as well as the sensitivity of the carpathian basin loess to the millennial scale climate variability recorded in other northern hemisphere records finally we suggest that the onset of loess formation in the investigated area occurred during the middle pleistocene transition and it was probably related to intensive silt production related to glacier dynamics in the alpine ice cap

luminescence dating of upper pleistocene loess from the island of susak in croatia abstract the loess paleosol sequence on the island of susak is a detailed late pleistocene archive of climate change in the north adriatic sea of croatia quaternary deposits on susak are up to 90 m thick and consist of loess loess derivatives and sand intercalated by numerous paleosols and at least three tephra layers infrared stimulated luminescence irsl dating was carried out on polymineral fine grained material thirteen samples were collected from two sections on susak to study the timing of loess accumulation and soil formation the single aliquot regenerative sar protocol as well as the multiple aliquot additive dose maad protocol were applied for equivalent dose d e determination the irsl ages were fading corrected independent age control is provided by radiocarbon dating of charcoal remains the results show that loess and loess derivatives from the investigated sections represent a very detailed record correlating to the marine isotope stage mis 3 with short periods of stronger sand deposition and occasional volcanic activity the extraordinary thickness of the deposits is very likely related to the vicinity of the river po plain which extended to the southeast due to marine regressions of the adriatic sea during the cold periods of the pleistocene

loess and soils in the eastern ebro basin abstract wind blown sandy and silty deposits were formed during the late quaternary in the ne iberian peninsula they are the most significant in the west mediterranean region together with those described in the tagus river basin iberian south subplateau forming small scattered patches across parts of the se ebro depression and sw catalan mediterranean range two major depositional environments are distinguished the first largest outcrop covers the lower ebro reaches on the se border of the ebro depression the prelitoral coastal range and the mora d ebre basin a second outcrop to the north consists of a few patches scattered over a wide amphitheatre surrounding the western tributaries of the segre river from the wind exposed segria platforms to the almenara range in its northernmost part they consist of highly sorted fine sands and silts 1 12 m thick though most typically 3 4 m thick and coarser than typical loess they are highly uniform lack any sedimentary structures and are pale ochre the deposits are calcareous 30 45 caco3 basic to alkaline and with some soluble salts five selected sequences of primary loess namely mas de l alerany tivissa guiamets batea and almenara were studied to ascertain deposit characteristics and soil development all sections show a consistent vertical granulometric variability that may be attributed to wind intensity changes and hinders the recognition of spatial particle size distribution pedogenesis is mostly related to calcium carbonate redistribution which accumulates as nodules large rhizocretions or biogenic calcite secondary gypsum batea and almenara sequences is probably related to primary gypsum blown from the source areas that was redistributed by leaching and precipitation at the bottom of the profiles in a few places mas de l alerany outcrop a fersialitic rubefacted recalcified soil indicates the presence of an older generation of loess while the dominant wnw winds and particle coarseness suggest that the loess originates from nearby alluvial fans and fluvial plains the presence of gypsum and mg anomalies may be evidence of more distant sources of the central ebro depression and ondara corb alluvial fans optical stimulated luminiscence osl ages for the more recent deposits guiamets batea almenara are between 18 and 34 ka while the old mas de l alerany sequence is more than 115 ka these ages indicate loess deposition during the last cold phases of the quaternary and with pedogenesis occuring during warm interglacial periods

stable isotope composition of bulk and secondary carbonates from the quaternary loess paleosol sequence in suttő hungary abstract stable carbon and oxygen isotope composition of pedogenic carbonates were studied from the quaternary loess paleosol sequence of sutt in hungary to investigate genetic processes in a paleoenvironmental context and to distinguish subtypes bulk carbonate samples taken at 2 cm vertical resolution and microscale secondary authigenic carbonates calcified root cells carbonate coatings hypocoatings and earthworm biospheroids and concretions at 10 cm resolution were analysed to interpret stable isotope variations isotope values of bulk samples were in the range of 2 6 to 13 9 and 2 3 to 17 0 vs vpdb for 13c and 18o respectively the isotope compositions of secondary carbonates clearly distinguished between the organically related and inorganic direct precipitation of the different subtypes in general secondary carbonates showed more depleted values than bulk samples calcified root cells have the most depleted isotope composition with mean values of 16 0 and 11 8 for 13c and 18o respectively results indicate that loess and paleosol secondary carbonates reveal pedogenetic information during the different climatic phases carbon and oxygen isotope analyses are valuable to classify secondary carbonates and to serve as proxies for the interpretation of paleoenvironmental conditions e g moisture conditions leaching the role of organic matter or vegetation secondary carbonates are more reliable than bulk samples because of their direct connection to the host strata

australian dust deposits modern processes and the quaternary record abstract dust raising and transport are common and important processes in australia today the aridity of the australian continent and high climatic variability result in widespread dust raising in the arid and semi arid areas and transport to the humid margins and surrounding oceans the supply of erodible particles appears to be the greatest limitation on total flux of transported dust dust raising is greatest in the lake eyre basin including the simpson desert and murray darling basin where internal drainage renews supplies of fine particles to the arid zone in the west and northwest dust entrainment is low despite considerable aridity the marine record of dust flux shows at least a threefold increase in dust flux compared with the holocene in the last glacial maximum in both tropical and temperate australia driven by weakened australian monsoon rains and drier westerly circulation respectively despite the widespread confirmation of aeolian dust deposits in southeastern and southwestern australia dated or quantified records are extremely rare the dominant model of australian dust deposits the clay rich parna is shown to be poorly substantiated while modern and ancient dust deposits examined in detail are shown to bear a strong similarity to conventional definitions of loess