the interrelation of glaciotectonic and glaciodepositional processes within the glacial environment abstract in recent years it has been recognised that ice sediment coupling occurred beneath the quaternary ice sheets that advanced over the soft sediments of lowland areas this paper looks in detail at the effects of this coupling on the sediments which results in glaciotectonic deformation and also discusses the interaction of deformation and deposition within the subglacial environment two types of glaciotectonic deformation are discussed that are produced by the active movement of ice 1 proglacial tectonics at the margin which include compressive fold styles such as listric thrusts and faults and open folding 2 subglacial tectonics formed beneath the glacier which include fold styles resulting from simple shear and represent a soft rock purely dynamic shear zone styles of deformation associated with stagnant ice are also investigated we argue that glaciotectonic deformation is a common phenomenon and an integral part of geological record from continental ice sheets it is suggested that zones of deformation within the sediment are related to similar zones of strain in the ice sheet and complex deformation sequences are produced by the superimposition of these differing styles upon one another as the ice sheet advances and retreats it is also argued that subglacial deposition and deformation are related and that on soft beds underformed till is rare whilst deformed till is very common

micromorphology of the lower pleistocene loess in the iranian loess plateau and its paleoclimatic implications abstract the loess deposits in iran are a valuable archive of regional paleoclimatic and paleoenvironmental information extensive sedimentological and chronological studies have been carried out on the middle to upper pleistocene loess successions during the past decades but there is an absence of comparable research in the older loess deposits recently a 19 m thick loess paleosol sequence was discovered in the central iranian loess plateau ilp which was paleomagnetically dated to 2 4 1 8 ma and thus represents by far the oldest loess known in northern iran here we present the results of a detailed micromorphological investigation of these lower pleistocene loess paleosol sequences red sequence from the ilp our main findings are as follows 1 the agh band red sequence deposits are an extremely thick soil complex comprising paleosols in different stages of development 2 the micromorphological index of soil development miseca suggests that the moderately and well developed paleosols in the red sequence formed in an environment with mean annual precipitation ranging from around 450 to 650 mm respectively and 3 miseca suggests that the red sequence formed under a semi arid to sub humid climate and thus under wetter and more favorable conditions than the overlying late pleistocene loess and modern soils

glaciation and tectonics in an active intracratonic basin the late palaeozoic itarare group parana basin brazil the parana basin 1 600 000 km2 is the largest intracratonic basin in southern south america and contains a thick 1300 m permo carboniferous glacial succession the itarare group this paper describes over 1700 m of drill core recovered during recent exploration for oil and gas itarare group sediments consist of massive and stratified diamictites interbedded with massive and graded sandstones and massive and laminated mudstones facies are interpreted as the product of sediment gravity flows in a glacially influenced marine basin three stratigraphic formations can be defined across the basin each consisting of a lowermost sandstone rich member overlain by a diamictite rich member examination of itarare group rocks both in core and outcrop shows that depositional processes were influenced by active faulting and downslope resedimentation on relatively steep and unstable substrate slopes primary glacial deposits such as tillites and associated striated pavements occur along the present eastern outcrop belt which probably coincided with the eastern basin margin during deposition of the itarare group ice masses fringing the eastern southern african and western bolivian basin margins supplied sediment to the basin in the form of fluvio glacial deltas fans and floating ice tongues this sediment was then resedimented downslope as debris flows and turbidites both stratigraphic relationships and the regional distribution of facies types identify a clear pattern of basin subsidence and step wise expansion by outward faulting within late proterozoic mobile belts the position of successive basin margins can be related to specific lineament structures in the underlying basement asymmetric expansion of the parana basin occurred along the northern and southern basin margins during deposition of the itarare group this expansion probably reflects shallow crustal adjustments activated by collisional movements along the andean margin of south america during the hercynian orogeny

styles of subglacial glaciotectonic deformation within the context of the anglian ice sheet a substantial proportion of the glacial sediments of east anglia england are chaotic and highly deformed this has been attributed to a direct glaciotectonic deformation or b slumping of glaciomarine sediments we show that interpretation a leads to a classification of subglacial glaciotectonic deposits into sites of constructional deformation where little or no erosion of the preglacial deposits has occurred and styles of deformation are preserved moving up in the sequence and excavational deformation where substantial erosion of preglacial sediments has occurred and deformational styles are superimposed on each other by using glaciological and geotechnical theory we show that the expression of these deformational styles in east anglia is a natural response to the stress fields imposed by the ice sheet and that in consequence their spatial relationships are explicable the depth of deformation is related to the geotechnical properties of till and substrate the stress and effective stress fields and found to be consistent with observations

stratigraphy and spatial and temporal paleoclimatic trends in southeastern eastern european loess paleosol sequences abstract the loess paleosol sections batajnica stari slankamen serbia mircea voda romania and stary kaydaky ukraine are presently located in areas of different types of steppe and are highly sensitive for recording climatic changes a stratigraphy for these three southeastern eastern european sections is presented based on pedostratigraphy and correlation of recently obtained susceptibility records with susceptibility data of other sections of the area koriten mostistea vyazivok of the chinese loess plateau and with the benthic 18o record of odp 677 six pedocomplexes were studied at the serbian and romanian sections and five at the ukrainian section the oldest are related to marine isotope stage mis 17 batajnica stari slankamen and mircea voda and mis 13 15 stary kaydaky some points concerning the existing loess chronostratigraphies of bulgaria ukraine and china are discussed comparative study of the profiles allows the tracing of paleoclimatic and paleoenvironmental changes in southeastern eastern europe in time and space reconstruction of paleoprecipitation based on susceptibility rainfall relationships and calculations of sedimentation rates are evaluated

luminescence chronology of the loess palaeosol sequence toshan northern iran a highly resolved climate archive for the last glacial interglacial cycle loess palaeosol sequences are highly resolved archives for palaeoenvironmental reconstruction and build an important link to correlate european and central asian loess sequences for the loess palaeosol sequence at toshan northern iran a luminescence based chronological framework was established the timing of dust accumulation and soil formation was investigated and thereby information on changes in palaeoenvironmental conditions in the region obtained for luminescence dating the 4e11 mm grain size fraction was used and the pirir290 approach was applied to polyminerals tests concerning bleachability dose recovery and anomalous fading were conducted the results show that residual doses have only minor influence on the determination of the equivalent dose the eemian mis 5e soil seems to be preserved but a chronological classification based on luminescence ages for this soil remains difficult the pirir290 age estimates from the lower part of the profile range from 104 9t o 127 8 ka lumi nescence ages from the central profile part point to an increase in dust accumulation starting around the mis 4 mis 3 transition furthermore a chronological framework for interstadial soils was developed indicating e g soil formation at around 40 ka during mis 3 and 26 ka during mis 2 the top part of the profile was dated to about 22 ka the age estimates show that the toshan loess profile is a highly resolved loess record providing a valuable climate archive for the last glacialeinterglacial cycle reflecting several climatic shifts represented by dust accumulation or enhanced degrees of soil formation stadials and interstadials

constraining the timing kinematics and cyclicity of mississippian early pennsylvanian glaciations in the parana basin brazil abstract ice contact deposits emplaced by late paleozoic ice age lpia glaciers are rarely exposed due to a low degree of preservation and their capping by thick glaciomarine deglaciation sequences in this paper we present new data on glacial cyclicity relative age constraints and paleoice flow interpretations for an ice contact succession of the lowermost itarare group in eastern parana basin brazil the 80 m thick ice contact complex rests over the itarare group basal unconformity and comprises four stacked informal stratigraphic units regarded as the depositional deformational record of three ice lobes advance retreat cycles glacial cycle 1 comprises a sheet of massive diamictite resting on striated pavements carved on devonian sandstones and topped by grooved fluted surfaces which indicate subglacial emplacement from a northward flowing ice lobe the glacial cycle 2 succession was deposited in a proglacial to ice marginal marine setting and subsequently deformed due to minor ice margin fluctuations of a westward southwestward flowing grounded ice lobe glacial cycle 3 is interpreted as a thick overridden push moraine composed of grounding line fan deposits capped by a subglacial diamictite emplaced by grounded ice advancing northwestward a middle visean early serpukhovian palynomorph assemblage was recorded in cycle two deposits representing the oldest late paleozoic glacial rocks in the parana basin the ice contact complex elucidates multiple waxing and waning phases of the windhoek ice sheet onto the eastern margin of the parana basin during the mississippian early pennsylvanian demonstrating that ice sheets of the early stages of the lpia were also present in the brazilian african domain of southwestern gondwana

geochronology of middle and upper pleistocene loess sections in hungary abstract the application of both thermoluminescence and infrared stimulated luminescence dating to the extensively studied classical hungarian loess paleosol sequences from basaharc mende and paks provides a reliable chronological framework and climatostratigraphic reconstruction for the last interglacial glacial cycle based on this combined luminescence dating study a new chronology is proposed for the young loess in hungary luminescence dating suggests that the loess below the mf2 horizon formed during the penultimate glaciation the mf1 horizon probably formed during an interstade within oxygen isotope stage 3 for the youngest loess overlying mf1 a very high accumulation rate was determined large time gaps occur above mf2 and mf1 indicating that most of the record of the last glaciation is missing in the standard sections at basaharc mende and paks either large discontinuities or a very low accumulation rate occurred in all three type sections during the soil forming periods high resolution studies of climatic proxies using this combined luminescence dating approach provide a reliable chronological framework for loess and loess derivatives of the last glacial cycle in hungary although a precise and complete chronostratigraphic reconstruction cannot be achieved from the incomplete records found at these sites

magnetostratigraphy and mid palaeolatitude vgp dispersion during the permo carboniferous superchron results from parana basin southern brazil rhythmites summary a detailed magnetostratigraphic and rock magnetism study of two late palaeozoic rhythmite exposures itu and rio do sul from the itarare group parana basin brazil is presented in this paper after stepwise alterning field procedures and thermal cleaning were performed samples from both collections show reversed characteristic magnetization components which is expected for late palaeozoic rocks however the itu rocks presented an odd flat inclination pattern that could not be corrected with mathematical methods based on the virtual geomagnetic pole vgp distributions correlation tests between the maximum anisotropy of the magnetic susceptibility axis k1 and the magnetic declination indicated a possible mechanical influence on the remanence acquisition the rio do sul sequence displayed medium to high inclinations and provided a high quality palaeomagnetic pole after shallowing corrections of f 0 8 of 347 5 e 63 2 s n 119 a95 3 3 k 31 which is in accordance with the palaeozoic apparent wander pole path of south america the angular dispersion sb for the distribution of the vgps calculated on the basis of both the 45 cut off angle and vandamme method was compared to the best fit model g for mid latitudes both of the sb results are in reasonable agreement with the predicted palaeo latitudinal s relationship during the cretaceous normal superchron cns although the sb value after the vandamme cut off has been applied is a little lower than expected this result in addition to those for low palaeolatitudes during the permo carboniferous reversed superchron pcrs previously reported indicates that the low secular variation regime for the geodynamo that has already been discovered in the cns might have also been predominant during the pcrs

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

sediment deformation beneath glaciers rheology and geological consequences experiments beneath breidamerkurjokull in iceland have led to development of flow laws for the subglacial till relating strain rate to shear stress and effective pressure and assuming either bingham fluid or nonlinearly viscous fluid behavior water pressures in the till are less than ice pressures and it is suggested that this may lead to infiltration of ice into the sediment which inhibits sliding at the ice sediment interface where water pressures are equal or near to ice pressures infiltration does not occur and sliding may result a one dimensional theory of subglacial deformation is developed in which the empirical flow law is coupled with a model of subglacial hydrology and consolidation this predicts stable states in which subglacial sediment either does not deform or a dilatant deforming horizon forms with positive effective pressures at the ice bed interface or unstable states where zero or negative effective pressures are predicted time dependent analyses show that response times following perturbations of the system may be of the order of 103 years and thus that unsteady behavior may be normal on glaciers flowing over unlithified sediment beds it is suggested that the natural variability of material properties in subglacial sediment beds leads to the development of drumlins on the glacier bed it is suggested that unstable deformation at zero or negative effective stress leads to piping in subglacial sediments at the glacier terminus and the growth of sediment floored subglacial tunnels their frequency is that which is sufficient to draw down subglacial water pressures so as to prevent unstable deformation where they discharge large water volumes subglacial sediments flow laterally toward them producing tunnel valleys this sediment is then removed by water flowing along the axial tunnel tunnel valleys can be regarded as the equivalent in soft sediment areas of eskers in bedrock areas

spectral analysis and modeling of microcyclostratigraphy in late paleozoic glaciogenic rhythmites parana basin brazil we investigate the depositional time scale of lithological couplets fine sandstone siltstone siltstone mudstone from two distinctive outcrops of permo carboniferous glacial rhythmites in the itarare group parana basin brazil resolving the fundamental issue of time scale for these rhythmites is important in light of recent evidence for paleosecular variation measured in these sequences spectral analysis and tuning of high resolution gray scale scans of sediment core microstratigraphy which comprises pervasive laminations reveal a comparable spectral content at both localities with a frequency suite interpreted as that of short term climate variability of recent and modern times this evidence for decadal to centennial scale deposition of these lithological couplets is discussed in light of the varvic character i e annual time scale that was previously assumed for the rhythmites

the paleoclimatic significance of deformation structures in neoproterozoic successions abstract this paper reviews the different types of soft sediment deformation structures that can form in glacial and non glacial settings and explores the potential use of these structures in resolving long standing debates in paleoenvironmental reconstructions of neoproterozoic glacigenic successions soft sediment deformation structures are created when compressional gravitational or shear stress is applied to unlithified sediments during or shortly after deposition in subglacial or ice marginal glacial settings shear and compressional stress imparted by ice moving on top of a deformable substrate or advancing ice buldozing unlithified ice marginal sediments can result in a wide range of folding faulting and shear structures in glaciofluvial or stagnant ice marginal setting gravitational collapse and remobilization of sediments associated with the melting of buried ice can result in normal faulting and broad folding in glaciolacustrine or glaciomarine settings compressional shear and gravitational types of deformation structures can occur as a result of grounding ice or icebergs rapid sedimentation and reworking downslope associated with high sedimentation rates in non glacial settings similar deformation structures can form as a result of slope instability and reworking of sediments downslope rapid sedimentation seismic shaking wave induced shearing or loading in this context two case studies are presented to demonstrate the type of paleoenvironmental information that an analysis of deformation structures can provide in the first case study analysis of deformation in the port askaig formation scotland reveals a distinctive stratigraphic distribution of deformation structures the types of deformation observed together with their recurrence over several 100s of meters and their basinal context are used to infer a seismic origin for the deformation which in turn suggests a significant tectonic control on sedimentation atop a record of ice margin fluctuations in a glaciomarine setting in the second example analysis of deformation in the smalfjord formation northern norway provides strong evidence for deformation by active ice overriding glaciofluvial deposits the types of deformation in this example together with its complexity scale and associated facies provide the strongest case for ice marginal deformation in sum analysis of deformation structures together with analysis of structural geology stratigraphy facies and facies associations can provide additional constraints on paleoenvironmental conditions at the time of deposition which can help us refine or test paleoenvironmental models proposed for this critical time period in earth history

deformation of a modern alluvial plain abstract the alluvial plain of the waal river the netherlands over 4000 m 2 showed large flow lobe like structures after it had fallen dry following floodings the upstream directed parabola shaped folds had mutual distances from

ubiquity of anomalous fading in k feldspars and the measurement and correction for it in optical dating anomalous fading rates were measured in k feldspars separated from 49 sediment samples mainly from north america the intensity of the optically stimulated luminescence was found to decrease linea

analysis and reinterpretation of deformation features in the rouge river valley scarborough ontario geometry and timing of deformation affecting ordovician bedrock and overlying pleistocene sediments in the rouge river valley near scarborough ontario are analysed to evaluate whether or not the structures are a result of glacial action or neotectonic activity extensive data on local and regional ice flow directions are used to evaluate the kinematic compatibility between the observed faults and folds and the local ice flow directions jointing and multiple episodes of faulting affect both the ordovician bedrock and the overlying pleistocene sediments at one site the bedrock is displaced by a normal fault by a minimum of 1 2 m crosscutting relationships constrain the majority of the faulting in the rouge river valley as being coeval with deposition of the lower bowmanville till during the nissouri phase ca 23 15 ka and possibly younger at one locality the youngest regional ice flow direction is northwestward however local ice flow directions are highly variable this can be explained by local perturbation enhanced by the presence of drumlinoid features in the area most deformation features are compatible with local and regional ice flow directions glaciotectonic ice push and ice thrust deformation affected the thorncliffe formation after about 23 ka although some faults appear to be kinematically incompatible with ice flow directions six boreholes drilled to 52 m depth revealed only minor vertical offsets of bedrock strata in the uppermost 20 m and an absence of obvious fault offsets deeper precluding the possibility that the faults observed in the surface exposures were caused by deep seated neotectonic stresses

patterns of late palaeozoic deglaciation in the parana basin brazil abstract the itarare subgroup middle carboniferous early permian of the parana basin of southeastern brazil contains the thickest most extensive and one of the longest records of late palaeozoic glaciation in all of the gondwana supercontinent glacially controlled deposition started as early as the middle carboniferous when lobate termini of ice streams from the windhoek ice sheet wis and rio grande do sul and asuncion ice caps moved into the parana basin lobes reached sea level and advanced grounded at least as far as 200 km into the basin stabilizing as tidal intertidal margins glaciation and glacial sedimentation occurred penecontemporaneously with the transgressive phase of the late palaeozoic tectonic cycle of the parana basin while gondwana was gradually moving away from the south pole evolution involved complex interaction of tectonic palaeogeographic and palaeoclimatic factors initial flooding of the basin by an epicontinental sea in the middle carboniferous may have provided moisture necessary for the growth of glaciers conversely episodes of sea level rise probably affected the stability of marine glaciers the palaeoclimatic setting for the wis and other ice masses at the margins of the parana basin was mostly temperate multiple ice advances are evidenced by subglacial tillites resting on striated and or glaciotectonized basement and deformed glacigenic sediments identified at different stratigraphic levels in the itarare subgroup glaciation reached its maximum expansion sometime between the late carboniferous and early permian gradually diminishing and vanishing in the late early permian the reconstructed palaeogeographic evolution favors a model of irregular melt back of ice masses particularly along the eastern margin of the parana basin in analogy with the deglacial pattern of the pleistocene laurentide ice sheet in north america retreat of marine glaciers was mostly associated with relatively simple accumulations or complex build ups of ice contact proglacial facies associations in glacial estuarine embayments fast retreat was mainly controlled by decoupling associated with sea level rise and intense calving in the terrestrial environment more fragmentary evidence shows that retreat may have involved several mechanisms including downwasting of stagnant inactive ice margins and destabilization by surging of glaciers moving over deformable sediments highstand sea level following ice wastage is often marked by widespread deposition of relatively thin marine beds at least four stratigraphically different basinwide marine horizons are recognized isostatic rebound of deglaciated margins of the parana basin is recorded by transition from deep marine beds to shallowing coarsening upward prograding sequences of littoral fluvio deltaic facies basinwards sourced from raised basin margins eventually upon emersion these constituted platforms for interglacial and postglacial peat development although glaciation lasted for a long time glacial sedimentation alternated with relatively long periods of intense and widespread subaerial and subaquatic submarine reworking of previously deposited glacigenic sediments and deposition of normal non glacial sediments that comprise the bulk of the itarare subgroup sequence thin coal beds which locally rest on fossil soils denote climatic amelioration during these interglacial phases

elevated temperature irsl dating of loess sections in the east eifel region of germany abstract it has been shown that the infrared stimulated luminescence signals measured at elevated temperature after an ir stimulation at 50 c post ir irsl are significantly more stable than the conventional irsl at 50 c ir 50 in this study a post ir irsl protocol using a second ir stimulation temperature of 290 c pirir 290 was applied to 17 polymineral fine grain 4 11 m samples from various loess sections in the eifel region wannenkopfe dachsbusch karlich and ariendorf with independent age control to test the reliability of ages using the pirir 290 signal the laboratory measured fading rates are below 1 decade on average for the pirir 290 both ir 50 and pirir 290 signals of 9 samples were found to be in field saturation the average ratio of the sensitivity corrected natural signal to the laboratory saturation level for the pirir 290 is 0 98 0 02 n 9 showing that field saturation is equal to laboratory saturation for the pirir 290 signal from polymineral fine grains from the eifel region minimum equivalent dose estimates were calculated from the characteristic saturation dose of the dose response curves giving minimum ages estimates of 230 420 ka and suggesting that the pirir 290 signal can be used to date loess to 300 ka the pirir 290 ages estimates of the samples from the wannenkopfe and dachsbusch sites are in good agreement with independent age control showing that the irsl dating using pirir 290 signal without fading correction is apparently reliable our data suggest that the loess units e f g and the lower part of h at the karlich site were accumulated 270 ka and that the palaeosol of the karlich interglacial i most likely developed during marine isotope stage mis 9 or earlier the pedocomplex on the top of loess bed ii at the ariendorf section can be correlated with mis 7

optical dating of holocene paleosol development and climate changes in the yili basin arid central asia optically stimulated luminescence osl dating was conducted on the k feldspar and quartz fractions of a holocene loess paleosol sequence in the yili basin in the core area of arid central asia a

melt out till in the edmonton area alberta canada till at two localities in the edmonton area alberta was formed mainly by passive melt out from glacier ice and not by lodgment by active ice or as a result of supraglacially derived flows this interpretation is based on the implications of in situ stratified glacial sediment below and within till and of large unlithified clasts of sediment derived from subtill deposits the interpretation is also supported by more general regional stratigraphic and structural observations such associated properties as subtill deformation a sharply planar till preglacial sediment contact sole marks and fabric support formation by melt out or illustrate local exceptions to this process regionally consistent preferred orientation of clasts is interpreted to represent preferred englacial orientation collective analysis of the principal eigenvectors of individual englacial fabrics and flow or resedimented till fabrics from a modem glacial environment and similar analysis for till at villeneuve near edmonton show the edmonton till to occupy the intermediate position in terms of orientation strength predicted by the melt out hypothesis in places preferred orientation is considered to have been disturbed by flow and diapirism induced by the process of thaw consolidation thus preferred clast orientation in till may show considerable deviation from a regional trend stratigraphy and sedimentology are used to classify the till and to relate individual exposures to regional environments of deposition

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

distribution lithology and provenance of peridesert loess deposits in northeastern iran abstract silty deposits cover different landforms bordering the city of mashhad in ne iran despite the potential of these deposits to provide important information regarding landscape evolution as well as land use management little information has been published on their nature and origin the main objective of this study was to determine the nature and origin of silty deposits in this area based on particle size distribution abrupt particle size change between silty deposits and underlying materials the shape and microtexture of quartz grains chemical and geochemical data and geochemical homogeneity of silty deposits from different landforms and geomorphic positions the silty deposits appear to be wind blown in origin and are classified as loess they show a particle size distribution similar to that of typical loess deposits containing more than 70 silt mostly coarse silt 35 45 and low quantities of clay and sand bulbous edges and evidence of wind transportation on quartz grains confirm the aeolian nature of the quartz silt the amount of carbonates and gypsum in loess deposits are mostly in the range of 10 32 and 4 15 respectively silty deposits around the study area are geochemically homogenous similar geochemical signatures of gypsiferous marls and loess deposits the existence of gypsum enriched layers in the loess deposits and the geomorphic position show that gypsiferous marls are the main source of aeolian deposits this is further confirmed by the existence of detrital palygorskite in loess layers and the presence of a high amount of palygorskite in gypsiferous marls since the silt in loess deposits is not the result of weathering processes the loess deposits of the study area bordering the large deserts of the central iranian plateau are defined as peridesert loess

glaciotectonic structures as useful ice movement indicators in glacial deposits four canadian case studies glaciotectonic deformation structures are useful directional indicators of ice movement but are rarely reported by north american authors being three dimensional they are commonly conspicuous in cleaned sections measuring just a few of them can provide accurate ice movement directions at a site and they assist in deciphering the interaction of past glaciers and their substrata this paper concentrates on structures generally less than 10 m long in unconsolidated sediments that were induced by overriding glacial ice examples and interpretations of various types of structures are presented in four new canadian case studies from british columbia and southern ontario that illustrate different deformational circumstances in sediments of various ages

glacial bedforms at the base of the permo carboniferous dwyka formation along the western margin of the karoo basin south africa well to poorly preserved sandstone surfaces with glacial grooves longitudinal ridges bulbous bedforms and large lodged clasts occur sporadically at the base of the dwyka formation along the western margin of the karoo basin the bedforms developed when ice overrode a thin 0 1 2 0m thick subaqueous icemarginal apron formed primarily during periods of ice front retreat bergstone mud and rain out diamicton blanketed the glacial bedforms the subglacial bedforms formed by i the lateral movement of water saturated sediment into low pressure zones caused by crevasses and cavities at the base of the ice ii the presence of areas of higher strength substrate due to variations in bed lithology and porewater dissipation and iii sediment flowage into low pressure zones on the leeside of obstacles formed in areas of higher strength substrate due to dissipation of pore water pressures and sediment compaction the preservation of the bedforms with their delicate slump fans is attributed to separation of the glacier sole from the substrate during a sudden rise in sea level a series of dynamic ice marginal events including feedback relationships between sea level oscillations isostatic responses ice margin fluctuations ice margin type and the type of substrate controlled the deposition of the basal sedimentary sequence and the formation of the associated glacial bedforms the presence of a complex combination of glacier related formative and depositional processes may have consequences for past interpretations of basal tillites

micromorphology and development of loess derived surface and buried soils along a precipitation gradient in northern iran abstract the northern footslopes of the alborz mountains and an extensive hill area in eastern golestan province are covered by thick 70 m loess deposits divided by different types of interstadial and interglacials paleosols the area shows a precipitation gradient of about 800 mm over 80 km north south along this gradient eight pedons of modern soils and six paleosols were selected in order to investigate the types of modern and past soil forming processes and to compare the degree of soil development of surface and buried soils the soils were described and sampled using standard sedimentological pedological laboratory analysis the soil ph and calcium carbonate contents show a decreasing trend with precipitation while soil organic carbon clay content and cation exchange capacity increase with rainfall the silt content however shows a decreasing trend with rainfall clay mineralogy of parental loess is illite chlorite smectite kaolinite from north to south the relative proportion of smectite in soil horizons increases reaching almost dominance in regions with typic xeric soil moisture regime smr 600 mm of rainfall in the areas with udic smr vermiculite increases and sometimes dominates micromorphology provides evidence for the formation of bt horizons and intensified decalcification and increase of clay mobilisation as indicated by b fabrics with increasing rainfall soils within the xeric and udic smrs are either alfisols or mollisols both showing clay illuviation features whereas clay mobilisation is very limited in the arid part of the area the paleosols show differential weathering degrees indicated by trends of increasing carbonate depletion clay mobilisation and clay enrichment with assumed paleo precipitation pedogenesis micromorphological properties and clay minerals in the last interglacial paleosols suggest similar climate controlled trends to those reflected in the modern soils

the paths and timing of late paleozoic ice revisited new stratigraphic and paleo ice flow interpretations from a glacial succession in the upper itarare group parana basin brazil abstract this paper examines a glacial diamictite bearing succession from the upper itarare group taciba formation in eastern parana basin brazil the object of study provides the opportunity to investigate in detail the late stages of glacial sedimentation during the late paleozoic ice age lpia in this sector of sw gondwana with implications for glacial cyclicity and regional paleo ice flow reconstructions sedimentology geological mapping and palynological analysis allowed the recognition of four facies associations comprising subaqueous outwash mass transport tide influenced delta front and tide influenced delta plain deposits the succession records at least two episodes of ice margin advance and retreat into a marine influenced environment and can be placed in the earliest permian based on the palynomorph assemblage cross stratification in outwash facies and deltaic deposits indicate sediment transport to the sw the same revealed by deformational structures in mass transport diamictites derived from downslope resedimentation of glaciomarine sediments during deglaciation a glacial source to ne is therefore indicated and is in agreement with paleo ice flow directions obtained from previously studied localities to the north this north derived early permian glaciation contrasts with glacial sources to the se recognized in the lower and middle intervals of the itarare group the scenario suggests a geometric reconfiguration of the parana basin during the lpia and the migration of ice centers with time during the late paleozoic ice age in sw gondwana

magnetic susceptibility and morphological characteristics of a loess paleosol sequence in northeastern iran abstract magnetic susceptibility of loess paleosol sequences is frequently used for paleoclimatic and paleoenvironmental studies a penultimate loess paleosol tappeh salam section from northeastern iran was studied to determine i morphologic sedimentologic and magnetic characteristics of the section ii the effect of high amount of carbonates and gypsum on the magnetic susceptibility and iii if any recognizable relationship between magnetic susceptibility and paleoenvironmental conditions during periods of soil formation and loess deposition existed the bulk magnetic susceptibility lfbulk of genetic horizons was measured to eliminate the effect of gypsum and carbonates the minerogenic magnetic susceptibility lfminero was calculated based on morphological characteristics five distinct parts were recognized part 1 and 4 are composed of unaltered loess deposits with easily visible gypsum crystals part 2 includes a series of bw by and bk horizons that ends to a last interglacial paleosol with a btk horizon in part 3 at the base of the section because of its extremely hard consistency part 5 has an abrupt boundary the lfbulk values of different layers of the horizons change from 40 9 10 8 m3 kg 1 in the weakly developed part 1 to 75 6 10 8 m3 kg 1 in the btk horizon the amount of gypsum plus carbonates is 13 6 40 9 making the interpretation of lfbulk difficult the lfminero makes the difference clearer through the section the lfminero of part 1 is 108 9 10 8 m3 kg 1 this unexpectedly high value may be expressed by anthropogenic addition of magnetic particles the lfminero of btk horizon exceeds 103 10 8 m3 kg 1 showing the effect of accumulation of iron oxides during warm and humid climate of the last interglacial period the 70 10 8 m3 kg 1 value for lfminero in part 4 can be attributed to parent materials part 5 has the lowest lfminero of 50 10 8 m3 kg 1 hydromorphic conditions in part 5 has induced the decomposition of iron oxide resulting in a decline in magnetic susceptibility the results of this study show the effectiveness of magnetic susceptibility properties for the interpretation of paleopedological and paleoenvironmental conditions of loess paleosol sequence in northeastern iran it should be noted that in the arid regions to avoid misinterpretation the effect of high amount of gypsum and carbonates must be taken into account by minerogenic magnetic susceptibility calculation

investigating soil magnetic properties with pedogenic variation along a precipitation gradient in loess derived soils of the golestan province northern iran abstract in the golestan province in northern iran extensive loess deposits and widespread loess derived soils crop out while a strong precipitation gradient 200 700 mm per year from north to south is characteristic temperature differences are negligible 17 18 c per year recently many studies on loess derived palaeosols and modern soils from this region were published however in these publications only limited information on the magnetic properties of loess and loess derived soils is given nor the potential of these properties to be applied as proxies for palaeoclimate reconstruction in order to study soil magnetic properties along the precipitation gradient in the golestan province six pedons of modern soils were selected the physicochemical properties the clay mineralogy and magnetic parameters of soil samples were analysed susceptibility measurements 20 2 130 77 10 8 m3kg 1 arm susceptibility values 0 00489 0 068 m3kg 1 irm values 0 0027 0 0105 am2kg 1 and hysteresis measurements provide significant evidences for an increase of the content of fine grained ferromagnetic minerals with increasing mean annual precipitation simultaneously the amount of sp sized particles increase magnetite maghemite and hematite are the major magnetic minerals in the studied samples whereby magnetite seems to be dominant in the soils of the loess plateau of northern iran by presenting data from this region of the northern iran for the first time another example is provided for the application of magnetic properties as proxies for the reconstruction of the paleoclimate the results are compared to data of the chinese loess plateau the russian steppe and loessic soils from the midwestern united state with similar relations of pedogenic susceptibility and map

carboniferous glaciotectonized sediments in the southernmost parana basin brazil ice marginal dynamics and paleoclimate indicators abstract carboniferous glaciogenic strata itarare gp in the southernmost parana basin brazil exhibit soft sediment deformation features previously interpreted as glaciotectonism these sediments were studied in detail to confirm that they were deformed by ice and to assess the nature of the glaciation depositional environments and paleoclimate in this region during the carboniferous five outcrops were described along a railroad transect that contains a conglomerate and diamictite facies with striated and faceted clasts a medium sandstone facies a fine grained silt clay rhythmite and mudstone facies with dropstones and diamictite pellets a sandy clinoform facies and a folded sandstone with interbedded mudstone facies the depositional environment for these sediments is interpreted as an outwash fan and fan delta from an ice proximal transitional terrestrial to estuarine setting rb k values from the rhythmites reflect a transition from a freshwater to brackish environment and the chemical index of alteration cia of the rhythmites ranges from 65 to 73 reflecting a relative increase in the degree of chemical weathering through time deformation features include widespread folding thrust faults hydrofractures decollement surfaces and piggyback fold thrust complexes the deformation is interpreted as evidence of a push moraine complex formed by at least two complete ice advance retreat cycles the occurrence of decollement surfaces plastically deformed proglacial sediments and hydrofractures indicate a dynamic warm based or polythermal glacier abundant outwash sediments rhythmites with dropstones and the shift to average cia values all support a temperate paleoclimate deformation structures indicate a nw direction of ice shove that is in agreement with the regional scale hypothesis that a nnw flowing lobe extended out of uruguay during the carboniferous and terminated in the southernmost parana basin this study demonstrates that late paleozoic glaciation in this region was more dynamic than previously understood with high frequency fluctuations in ice marginal positions

deformation of till beneath ice stream b west antarctica the behaviour and possible instability of the west antarctic ice sheet depend fundamentally on the dynamics of the large ice streams which drain it model calculations show that most ice stream velocity arises at the bed1 2 and radar sounding has shown the bed to be wet3 but the basal boundary condition is not well understood seismic evidence from the upstream b camp upb on the siple coast of west antarctica4 shows that the ice stream there rests on a layer of unconsolidated sediment averaging 5 or 6 m thick in which the water pressure is only 50 kpa less than the overburden pressure because this thin layer occurs well inland beneath an active ice sheet and rests on a surface showing flutes4 characteristic of glacial erosion5 we presume that it is glacial till we propose here that deformation within the till is the primary mechanism by which the ice stream moves and we discuss implications of this hypothesis

anisotropy of magnetic susceptibility and sedimentary cycle data from permo carboniferous rhythmites parana basin brazil a multiple proxy record of astronomical and millennial scale palaeoclimate change in a glacial setting in this study we examine glaciogenic rhythmites from the late palaeozoic itarare group paranabasin brazil we conduct spectral analysis on lithological cycle couplet thick ness series and declination of maximum axis of anisotropy of magnetic susceptibility ellipsoidal tensor k1 data we tested the efficiency of k1 as a palaeoclimatic proxy to constrain the time scale of harmonic features in the data we analysed the couplet thickness spectra converting the spectra to the time domain using an astronomical calibration based on milankovitch frequency ratios comparison of the two rhythmites provides insights into their sedimentation rate evolution and cyclicity millennial scale mechanisms of climatic origin influenced the deposition of both rhythmites generating the lithological couplets and are consistent with millennial scale variations recognized as triggers for large scale climatic changes during the late pleistocene the common harmonic features in the couplet thickness and k1 spectra support the view that the azimuth of the k1 axis in sedimentary fabric is a useful palaeoclimatic proxy reflecting sedimentation processes that were directly influenced by flow induced sediment transport which is linked to external climate factors

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

a paleoclimatic review of southern south america during the late paleozoic a record from icehouse to extreme greenhouse conditions abstract this paper provides a review of the late mississippian to permian paleoclimatic history for southern south america based on lithologic indicators biostratigraphic information and chronostratigraphic data the region is divided into three major types of basins 1 eastern intraplate basins e g parana basin 2 western retroarc basins e g paganzo basin and 3 western arc related basins e g rio blanco basin four major types of paleoclimatic stages are recognized in these basins 1 glacial late visean early bashkirian 2 terminal glacial bashkirian earliest cisuralian 3 postglacial cisuralian early guadalupian and 4 semiarid arid late guadalupian lopingian the glacial stage began in the late visean and continued until the latest serpukhovian or early bashkirian in almost all of the basins in southern south america during the bashkirian earliest cisuralian terminal glacial stage glacial deposits disappeared almost completely in the western retroarc basins e g paganzo basin but glaciation persisted in the eastern basins e g parana and sauce grande basins a gradual climatic amelioration postglacial stage began to occur during the earliest permian when glacial deposits completely disappeared across all of south america during this interval glacial diamictites were replaced by thick coal beds in the parana basin while north south climatic belts began to be delineated in the western basins which were likely controlled by the distribution of mountain belts along the panthalassan margin of south america towards the late permian climatic belts became less evident and semiarid or arid conditions dominated in the southern south america basins eolian dunes playa lake deposits and mixed eolian fluvial sequences occur in the parana basin and in the western retroarc basins volcanism and volcaniclastic sedimentation dominated along the western margin of south america at that time the stratigraphic record obtained in southern south america supports a long duration transition from icehouse to extreme greenhouse conditions

genesis and evolution of a syn orogenic basin in transpression insights from petrography geochemistry and sm nd systematics in the variscan pedroches basin mississippian sw iberia abstract the pedroches basin is an outstanding syn orogenic variscan mississippian depocenter located in the vicinity of and overstepping onto the neoproterozoic cadomian suture between the ossa morena and central iberian zones of the sw iberian massif its formation appears to be related to transtensional processes at a major releasing bend in the reactivated suture during sinistral escape of the ossa morena zone from the zone of frontal variscan collision between northern gondwana and laurussia subsequent basin inversion resulted in compartmentalization and internal deformation and was probably related to transpression at a restraining bend along the reactivated suture badajoz cordoba shear zone basin fill consists of both igneous and metasedimentary rocks generally deposited in a shallow marine storm dominated platform environment by using new petrographic geochemical and sm nd isotopic data we attempt to characterize 1 the sources and geological evolution of the pedroches basin fill and 2 the processes involved in basin development and sediment supply and dispersal sampling was carried out in both sedimentary and igneous rocks belonging to three major structural units within the central part of the basin guadiato unit guadalbarbo unit and south pedroches valley unit the combined nd isotopic and geochemical data from the pedroches mississippian metasedimentary rocks indicate an upper continental crust provenance and a high degree of sedimentary recycling of these materials throughout the basin i e they are derived from old recycled upper crust without any significant juvenile component despite the presence of interbedded basaltic rocks the igneous rocks in turn correspond to submarine basalts and trachy andesitic basalts plus some hybrid rocks including crust derived components concerning the mafic rocks major element compositions reveal a tholeiitic and transitional tholeiitic character for the guadalbarbo unit rocks morb type and an alkaline affinity for those of the guadiato unit trace element analyses along with sm nd isotopic ratios suggest two kinds of provenance sources for the pedroches basin syn sedimentary igneous rocks 1 an important crust contaminated and or old enriched mantle source for the guadiato unit and the pedroches batholith and 2 a time integrated depleted mantle source for the guadalbarbo rocks in which no significant interaction with continental crust components is discernible these latter rocks suggest that a strong attenuation or even almost complete tectonic and or thermal erosion of the continental lithosphere was reached at least locally in this region

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

an abrupt shift in dust source on the chinese loess plateau revealed through high sampling resolution osl dating abstract the source of dust that forms the extensive deposits of loess exposed on the chinese loess plateau is highly debated in particular it is not clear whether sources can change abruptly within individual loess units or whether local influences on source can override the influence of far travelled components high vertical sampling resolution 10 40 cm optically stimulated luminescence osl dating of sediments on the loess plateau in china has been successful in providing detailed independent age models for loess accumulation here osl behaviour is used to infer a shift in loess sediment source during the last glacial period osl dating procedures have often utilised the widely applied single aliquot regeneration sar protocol on quartz grains detailed sar osl dating of the last 45 ka of sedimentation at beiguoyuan section on the north of the loess plateau demonstrates anomalous and statistically significant age increases and scatter in age estimates in samples from a c 2 5 m unit at about 20 ka compared to samples above and below many of these samples also fail internal dose recovery tests and show anomalous luminescence signal properties deconvolution of osl decay curves into first order components reveals that many of the age overestimating samples have a significant ultrafast component this behaviour is restricted to the 2 5 m segment and is only likely to be uncovered using high sampling resolution luminescence analysis combined with heavy mineral grain size and geochemical evidence this suggests that the source of material in this unit abruptly shifted at the last glacial maximum potentially to a local source rather than well mixed and recycled multiple distant sources as appears to be the case at other times at the site and other studied sections on the loess plateau the environmental causes of this source shift may be tied to abrupt climate change during the last glacial maximum and demonstrate the highly dynamic nature of the locations of dust generation during the last glacial period the change in source also adds complexity to standard climate proxy analyses of loess using sediment properties

soil formation in loess derived soils along a subhumid to humid climate gradient northeastern iran abstract in order to contribute to the understanding of carbonate enrichment and clay illuviation in loess derived soils of subhumid to humid regions the development of soils was studied along a climate gradient with xeric and udic soil moisture regimes smr and thermic and mesic soil temperature regimes str respectively in the golestan province northeastern iran six representative pedons along a climate gradient were investigated soils were classified mainly as hapludalfs and haploxeralfs stability of the geomorphic surface under forest vegetation associated with high leaching conditions has provided appropriate conditions for decalcification followed by clay migration through the profile and formation of argillic horizons in all the studied soils clay content of the bt horizons soil organic carbon concentration of the a horizons and depth of the bk horizons increased significantly with increasing precipitation and decreasing temperature there was a considerable decrease in silt content with soil development the main pedofeatures observed in the bt horizons were clay coatings and decalcified zones nodules coatings and hypocoatings were the main calcitic pedofeatures observed in the bk horizons occurrence and preservation of clay coatings were more pronounced in the udic regions with illite and vermiculite as the dominant clay minerals type of clay minerals shrink swell properties and precipitation rate are factors affecting the abundance and preservation of clay coatings in the strongly developed horizons of the udic smr the occurrence of vermiculite clay minerals could reduce the shrink swell potential and increase the amount of clay coatings the presence of crystallitic b fabrics and the high carbonate contents caco 3 in the lower horizons bk were mainly related to decalcification processes under descending water flow in the overlying horizons

late paleozoic glaciotectonic structures in northern parana basin brazil abstract fluviatile deltaic sediments containing thin coal layers and glaciofluvial sediments of the itarare subgroup late paleozoic cropping out near cerquilho northern parana basin exhibit post depositional deformation such as recumbent and drag folds shear fractures faults and shear lamination the deformation occurs in an interval of 3 4 m thick and is confined between horizontal strata the deformed strata are directly overlain along a horizontal erosional tectonic contact surface by a silty sandy massive 1 m thick clast poor tillite deformation shows a consistent geometry indicating a predominant vergence toward the ssw having been developed under a horizontal stress oriented from nne to ssw the deformation is interpreted to be of glaciotectonic origin associated with an ice readvance in the area the glacier moved toward the ssw on relatively soft deformable sediments depositing the subglacial till on top of them the tillite shows parallel upglacier dipping shear fractures at its base and wedge like intrusions into the underlying sandstone probably formed during its subglacial deposition the tillite is overlain by cyclic braided stream fluviatile sandstone beds the top of these shows deformations small recumbent folds and reverse faults below another clast poor silty sandy tillite this could represent another glacial readvance with subglacial deposition of till occurrence of glaciotectonic deformation overlain by subglacially deposited tillites in the cerquilho area indicates glacier readvances and permanence of the glacial influence in the upper part of the itarare subgroup absence of incorporated material from the underlying deformed sediments in the tillite and the style of the deformations suggest an unfrozen water saturated mostly unconsolidated substratum these conditions may have generated instability and fast ice flow of the glacier they also suggest that the sediment may have most likely failed in this manner under rapidly applied stresses associated with a surging behavior of the retreating glacier

patterns of late paleozoic glacial sedimentation on the southeast side of the parana basin brazil abstract during the late paleozoic glaciation glaciers moved from southern africa over a platform composed of crystalline and sedimentary rocks into the subsiding parana basin of southeastern brazil in each successive glacial advance the platform was eroded and is marked by crescentic gouges striae roches moutonnees grooves and glacially modified valleys the glacial sediments which are found on the platform in southeastern brazil and margins of the parana basin were deposited from grounded ice and are termed terrestrial these sediments which are best exposed in the northern part of the study area are composed of supraglacial deposits such as layers of diamictite flow tillite interbedded with sandstones and minor amounts of lodgement tillite the supraglacial deposits are frequently faulted and the sandstones show pull apart structures and abnormal dips these features and others suggest that ice retreat in the terrestrial environment was primarily by down wasting the glaciogenic sediments found within the subsiding parana basin are termed basinal even though it is not certain that they were all deposited in a subaquatic environment they are composed primarily of sandstones siltstones shales and mudstones interbedded with massive and laminated diamictites it is suggested that the massive diamictite was deposited from the base of the advancing glaciers by basal melting during ice retreat from water filled parts of the basin unstable masses of glaciogenic debris flowed down slope resulting in layered debris flows and in some instances chaotic debris flows which may have been triggered by subaquatic slupms and slides as the ice continued to retreat to the margin of the basin a complex of subaquatic outwash including deltaic sands was deposited minor varvites were deposited in shallow restricted embayments in the shoreline which were flooded with fresh glacial meltwaters deposits of retreat including the varvites interfinger with marine fossiliferous sediments which suggests that the water level in the basin was rising during deglaciation it is not known how may times glaciers advanced into the parana basin but recent studies show that there were at least nine glaciations in the northern part of this study area covering a time span of from 10 to 35 million years

the ponto caspian region environmental consequences of climate change during the late pleistocene evolution of the caspian and black sea pont basins environments was analyzed in comparison and both general and specific features of their development under multi scale and multi directional changes of climate during the late pleistocene were identified the cold extensive transgressions of the caspian sea and the transgressions of the caspian type of the pontian basin not exceeding the present sea level developed synchronously in the cold glacial climatic epochs the maximum height of level of the caspian transgressions was limited by the height of the manych threshold and the transgressions of the caspian type in the pontian basin by the height of the bosporus threshold the warm small transgressions of the caspian sea and the marine mediterranean type transgressions of the pont with maximum level developed during the warm interglacial epochs in the caspian these occurred mainly during the interglacial endothermal cool and moist phases while marine transgressions of the pont correlated with the interglacial transgressions of the world ocean the cold transgressions of the caspian sea and the caspian type transgressions of the pontian basin developed asynchronously with the transgressions of the world ocean

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

pedogenic carbonates archive modern and past precipitation change a transect study from soils and loess paleosol sequences from northern iran abstract stable carbon and oxygen isotope compositions in soil carbonates and in soil organic matter provide insights into paleo climatic conditions especially in arid and semiarid regions where carbonate is abundant in soils we here investigate 13c and 18o isotope composition of bulk carbonate pedogenic carbonate nodules and organic carbon from modern soils developed along a precipitation gradient entisol inceptisol mollisol and alfisol and paleosols formed within loess units in northern iran 13c values of organic carbon in the modern soils ranged from 19 5 in the arid and semiarid regions to 24 in the more humid regions with forest vegetation 13c values of bulk carbonate in the modern soils ranged from 12 1 at the wettest sites to 0 8 at the drier sites and thus a 550 mm increase in precipitation leads to a 11 decrease in 13c values of bulk carbonate in the modern soils 13c values of pedogenic carbonate nodules in the semiarid areas show higher values by 3 4 more than the regions with forest vegetation unlike 13c values of pedogenic carbonate nodules the 18o values of pedogenic carbonate nodules of modern soils in this study did not display pronounced changes across the sections the change in 13c of carbonates and organic carbon is consistent with the present above ground vegetation consisting of a mosaic of habitats with differences in the proportion of c3 and c4 vegetation tending to larger c4 contribution with increasing aridity the 13c values of carbonates coupled with climate data of the region confirm seasonal bias in the formation of carbonate nodules in the modern soils seen in studies elsewhere the 13c values of pedogenic carbonate nodules in the paleosols range from 10 in humid areas to 7 2 in semiarid areas the trends in 13c composition in modern soils are also visible in the 13c composition in the paleosols suggesting that in the foothills of the alborz and iranian loess plateau a precipitation gradient existed also in the last interglacial

dating middle pleistocene loess from stari slankamen vojvodina serbia limitations imposed by the saturation behaviour of an elevated temperature irsl signal abstract recent advances in post ir irsl dating have led to breakthroughs in dating upper middle pleistocene loess sequences here an elevated temperature post ir ir protocol using a second ir stimulation temperature of 290 c is applied to eleven polymineral fine grain 4 11 m samples from the lower part of the middle lower pleistocene stari slankamen loess palaeosol sequence with the aim of refining the site s age model and investigating the behaviour of both the ir50 and the pirir290 signals in material close to or in luminescence signal saturation both signals from the 8 samples below the prominent erosion surface represented by a gravel layer at 13 m were found to be in field saturation i e no systematic increase in burial dose with depth the average ratio of the sensitivity corrected natural signal to the laboratory saturation level for the pirir290 is 1 00 0 03 n 8 indicating that field saturation is equal to laboratory saturation for this signal minimum equivalent dose estimates were calculated from 2 d0 values giving minimum age estimates of 230 390 ka this result suggests an upper limit for dating these loess deposits of 300 ka the age estimate of the younger sample ssk2 is in good agreement with the quartz osl age showing that the pirir290 signal is bleachable in nature and can be used to date material as young as 20 ka our data suggest that the loess unit v l2 accumulated during marine isotope stage mis 6 and that the erosional event marked by an unconformity and gravel layer between loess units v l2 and v l3 has a minimum age of 170 ka pedocomplex v s1 can be correlated with the complete mis 5 period furthermore we suggest a minimum age of 250 ka for the loess unit v l3 and palaeosols v s3 v s4 and v s5 considerably older than proposed by many previous studies