laboratory experiments on the formation of subaqueous depositional gullies by turbidity currents abstract gullies and furrows are shallow sub parallel features widespread on the seafloor and some lacustrine environments vast fields of linear channels of erosional origin called furrows with spacings of meters and up to hundred of meters are common in settings with relatively low seafloor slopes and have been previously ascribed to helical motion in benthic boundary layers submarine gullies are linear donwslope trending features of erosional depositional or mixed nature commonly observed in the upper continental slope submarine canyon walls and other relatively steep submarine environments while gully fields have been associated to the action of unconfined turbidity currents and other cascading dense flows their relatively large spacings ranging from several hundreds of meters to 1 2 km suggest that these features might be the result of other mechanisms different than boundary layer helical motion in this paper we propose an alternative mechanism for the initiation of gullies observed in relatively steep seabed gradients downslope of a seabed slope change such as those observed in continental margins self slope break or submarine canyon walls our working hypothesis is that gullies could be the result of a centrifugal instability that sets in interfaces of gravity currents as they flow through a bedslope transition since for these cases the centrifugal force excess is of the same order of magnitude of the driving force and therefore a potential source of flow instability we propose that gully spacing might be controlled by the magnitude of the centrifugal force scaling roughly with the radius of curvature of the transition slope break we also present experimental evidence on the formation of longitudinal features resembling slope gullies that were created in a laboratory tank after running successive supercritical depositional turbidity currents through a slope change similar to that observed in continental margins gullies in the tank developed through differential deposition only and showed spacing an order of magnitude larger that that expected from a boundary layer helical motion origin these experimental results along with the observation that gullies were not formed in the tank without a bed slope change low to high support the hypothesis of a centrifugal instability origin for longitudinal features in relatively steeper submarine settings our experimental results also support our first order approximate gully spacing rule which is in general agreement with field observations of gully spacing in upper continental slopes and submarine canyon walls

3d crosshole ert for aquifer characterization and monitoring of infiltrating river water the hydrogeological properties and responses of a productive aquifer in northeastern switzerland are investigated for this purpose 3d crosshole electrical resistivity tomography ert is used to define the main lithological structures within the aquifer through static inversion and to monitor the water infiltration from an adjacent river during precipitation events and subsequent river flooding the river water resistivity increases as a consequence the electrical characteristics of the infiltrating water can be used as a natural tracer to delineate preferential flow paths and flow velocities the focus is primarily on the experiment installation data collection strategy and the structural characterization of the site and a brief overview of the ert monitoring results the monitoring system comprises 18 boreholes each equipped with 10 electrodes straddling the entire thickness of the gravel aquifer a multichannel resistivity system programmed to cycle through various four point electrode configurations of the 180 electrodes in a rolling sequence allows for the measurement of approximately 15 500 apparent resistivity values every 7 h on a continuous basis the 3d static ert inversion of data acquired under stable hydrological conditions provides a base model for future time lapse inversion studies and the means to investigate the resolving capability of our acquisition scheme in particular it enables definition of the main lithological structures within the aquifer the final ert static model delineates a relatively high resistivity low porosity intermediate depth layer throughout the investigated aquifer volume that is consistent with results from well logging and seismic and radar tomography models the next step will be to define and implement an appropriate time lapse ert inversion scheme using the river water as a natural tracer the main challenge will be to separate the superposed time varying effects of water table height temperature and salinity variations associated with the infiltrating water

intra slope canyon morphology and its modification by rockfall processes u s atlantic continental margin abstract side scan sonar data have been acquired at three different range settings and scales for a section of the continental slope the data allow new perspectives on canyon morphology at varying complementary resolutions both regional context and site specific details are provided intra slope canyons on the lower slope are associated with outcrops of middle eocene carbonate rocks canyon geometries are heavily influenced by structural patterns of intersecting joints drop core analyses of surface sediments suggest that intra slope canyon formation is not a geologically recent event but occurred before 50 000 yrs b p within the canyons rocky debris results from episodic rockfall activity from the steep canyon walls dating of canyon floor sediments with inclusions of rockfall debris at one location suggests the last discrete period of rockfall there began about 10 000 yrs b p and ended about 6000 yrs ago the rockfall activity may have coincided with a period of increased submarine dissolution along the margin that accompanied the upslope migration of the western boundary undercurrent elements of the lower slope terrain may reflect surface solutional degradation of the joint patterns associated with the eocene outcrops over longer time periods

sedimentary processes on the atlantic continental slope of the united states abstract until recently the sedimentary processes on the united states atlantic continental slope were inferred mainly from descriptive studies based on the bathymetry and on widely spaced grab samples bottom photographs and seismic reflection profiles over the past 6 years however much additional information has been collected on the bottom morphology characteristics of shallow subbottom strata velocity of bottom currents and transport of suspended and bottom sediments a review of these new data provides a much clearer understanding of the kinds and relative importance of gravitational and hydrodynamic processes that affect the surface sediments on the rugged slope between georges bank and cape lookout n c these processes include 1 small scale mass wasting within submarine canyons and peripheral gullies 2 density flows within some submarine valleys 3 sand spillover near the shelf break 4 sediment creep on the upper slope and 5 hemipelagic sedimentation on the middle and lower slope the area between georges bank and hudson canyon is further distinguished by the relative abundance of large scale slump scars and deposits on the open slope the presence of ice rafted debris and the transport of sand within the heads of some submarine canyons between cape lookout and southern florida the slope divides into two physiographic units and the topography is smooth and featureless on the florida hatteras slope offshelf sand spillover and sediment winnowing related to gulf stream flow and possibly to storm driven currents are the major processes whereas hemipelagic sedimentation is dominant over the offshore slope along the seaward edge of the blake plateau north of the blake spur slumping generally is absent south of cape lookout although one large slump scarp related to uplift over salt diapirs has been identified east of cape romain future studies concerning sedimentary processes on the atlantic slope need to resolve 1 the ages and mechanisms of mass wasting 2 the accumulation rates and thicknesses of hemipelagic sediments and 3 the causes and variability of offshelf sand spillover sediment winnowing and canyon transport

surface nuclear magnetic resonance tomography groundwater is the principal source of freshwater in many regions worldwide expensive drilling borehole logging and hydrological testing are the standard techniques employed in groundwater exploration and management it would be logistically beneficial and cost effective to have surface based nonintrusive methods to locate and quantify groundwater occurrences and to estimate other key hydrological parameters surface nuclear magnetic resonance snmr techniques which are based on the spin magnetic moment precession of protons in the hydrogen atoms of water offer the possibility of achieving these goals current snmr practices are based on 1d inversion strategies these simple strategies impede applications of snmr techniques in hydrologically complex areas to address this issue we introduce a very fast 2d snmr tomographic inversion scheme and apply it to four series of measurements simulated for a perched water lens model whereas the new 2d scheme correctly reconstructs all important characteristics of the original model 1d strategies produce highly inaccurate misleading results

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

new age constraints for the saalian glaciation in northern central europe implications for the extent of ice sheets and related proglacial lake systems abstract a comprehensive palaeogeographic reconstruction of ice sheets and related proglacial lake systems for the older saalian glaciation in northern central europe is presented which is based on the integration of palaeo ice flow data till provenance facies analysis geomorphology and new luminescence ages of ice marginal deposits three major ice advances with different ice advance directions and source areas are indicated by palaeo ice flow directions and till provenance the first ice advance was characterised by a southwards directed ice flow and a dominance of clasts derived from southern sweden the second ice advance was initially characterised by an ice flow towards the southwest clasts are mainly derived from southern and central sweden the latest stage in the study area third ice advance was characterised by ice streaming hondsrug ice stream in the west and a re advance in the east clasts of this stage are mainly derived from eastern fennoscandia numerical ages for the first ice advance are sparse but may indicate a correlation with mis 8 or early mis 6 new pirir290 luminescence ages of ice marginal deposits attributed to the second ice advance range from 175 10 to 156 24 ka and correlate with mis 6 the ice sheets repeatedly blocked the main river drainage pathways and led to the formation of extensive ice dammed lakes the formation of proglacial lakes was mainly controlled by ice damming of river valleys and major bedrock spillways therefore the lake levels and extends were very similar throughout the repeated ice advances during deglaciation the lakes commonly increased in size and eventually drained successively towards the west and northwest into the lower rhine embayment and the north sea catastrophic lake drainage events occurred when large overspill channels were suddenly opened ice streaming at the end of the older saalian glaciation was probably triggered by major lake drainage events

3 d view of erosional scars on u s mid atlantic continental margin deep towed side scan and bathymetric data have been merged to present a 3 d view of the lower continental slope and upper continental rise offshore atlantic city new jersey carteret canyon narrows and becomes nearly stranded on the lower slope where it leads into one of two steep walled flat floored erosional chutes the floors of the chutes cut into semilithified middle eocene siliceous limestones are marked by downslope trending grooves the grooves are interpreted to be gouge marks formed during rock and sediment slides on the uppermost rise beneath the chutes is a 40 m deep depression the origin of the depression is believed to be related to material moving downslope and encountering the change in gradient at the slope rise boundary downslope of the depressi n are channels trails and allochthonous blocks the lack of significant post early miocene deposits implies that the lower slope offshore new jersey has yet to reach a configuration conducive to sediment accumulation the age of erosion on the lower slope apparently ranges from late eocene early miocene to the recent geologic past

is there a possibility to correct fossil n alkane data for postsedimentary alteration effects abstract the long chain n alkane composition of plant material can significantly differ between plant groups e g trees and grasses due to their relative recalcitrance they have been employed in paleoecological research as molecular proxies for different types of vegetation most of those paleoenvironmental studies rely on the assumption that characteristic molecular fingerprints of plant material are preserved in the fossil organic material without significant alteration however there exists evidence that n alkane distributions may change in the course of plant litter degradation here the authors propose and discuss a conceptual approach to the correction of n alkane patterns in paleosols and terrestrial sediments for postsedimentary alteration effects this might have potential to improve paleoenvironmental reconstructions derived from these molecular fossils in soil depth profiles typically a correlation between the oep odd over even predominance and paleoecological valuable long chain n alkane ratios lars can be found similar relationships have been also obtained from n alkane records in paleosols with the oep serving as a proxy of microbial reworking the correction procedure applies oep vs lar regression functions to correct fossil lars for degradation effects the regression functions have been derived from modern soils the application of the procedure and its significance for paleoecological interpretations is demonstrated on a case study of a loess paleosol sequence 400 700 ka in romania it is shown that changes in the c27 c31 n alkane ratio at this site are closely related to degradation effects rather than to changes in the paleovegetation e g tree vs grass abundance however it was found that the c29 c31 ratio is a more suitable paleoenvironmental proxy at the mircea voda site the results indicate that there is a future potential to correct fossil n alkane ratios via the oep lar relationship however at the moment a general straight forward application of this approach might be critical due to lack of extended and diverse n alkane records from modern soils the need of more systematic n alkane studies on soil profiles is highlighted to improve knowledge concerning dynamics and actual mechanisms of postsedimentary lar and oep changes

stable isotope δ13c δ15n δ18o record of soils in buryatia southern siberia implications for biogeochemical and paleoclimatic interpretations stable isotope analyses of soils significantly contribute to a better understanding of biogeochemical and paleoenvironmental processes this paper presents and discusses stable carbon nitrogen and oxygen isotope 13c 15n and 18o data of representative soils of buryatia southern siberia in undisturbed soils kastanozem phaeozem gleysol podzol leptosol 13c and 15n values of soil organic matter som increase from the organic layers o layers to the mineral topsoils ah horizons and subsoils this primarily indicates advanced c and n mineralization in lower soil horizons and reflects the input of fresh litter in the o layers combined with numerical ages these data indicate that during the last ca 40 ka no c4 grasses prevailed in semiarid regions of buryatia disturbed soils ploughed chernozem and an anthrosol do not show with depth increasing 13c and 15n values but are characterized by fluctuating depth profiles high 15n values in the anthrosol up to 10 5 point to an open n cycle in a middle and late holocene aeolian paleosol record burdukovo 18o of the hemicellulose biomarkers arabinose and xylose show minima in the dark humic buried a horizons and maxima in the greyish silty fine sand layers this reflects the alternation of more arid and more humid conditions this interpretation is also in agreement with higher grain size ratios 20 63 m 2 6 m in the greyish fine sand layers documenting increased wind strength and dust supply som 13c and 15n values of o layers and ah horizons were furthermore investigated along an altitudinal transect in the khamar daban mts from 470 m to 1800 m a s l generally 15n values decrease with increasing altitude giving evidence of more closed n cycles at higher altitudes which are characterized by lower temperatures as an exception 15n of the ah horizons above 1500 m reveals conspicuously positive values presumably because of frequent burning of the dwarf pine belt with high n losses due to volatilization 13c shows no significant altitudinal trend above 750 m a s l but more negative values below 750 m a s l this may be attributed to frequent temperature inversions close to lake baikal similarly this inversion inducing fog and higher humidity close to lake baikal could also explain why 18o of the hemicellulose biomarkers arabinose and xylose do not reflect the altitude effect as it could be expected from 18o of precipitation

terrace styles and timing of terrace formation in the weser and leine valleys northern germany response of a fluvial system to climate change and glaciation abstract in glaciated continental basins accommodation space is not only controlled by tectonics and sea level but also by the position of ice sheets which may act as a regional base level for fluvial systems although the pleistocene terrace record of major river systems in northwestern europe has been investigated by many authors relatively little attention has been paid to base level changes related to glacier advance retreat cycles and how these regional changes in base level interacted with river catchment processes this study provides a synthesis of the stratigraphic architecture of middle pleistocene to holocene fluvial terraces in the upper weser and middle leine valley in northern germany and links it to glaciation climate and base level change the depositional architecture of the fluvial terrace deposits has been reconstructed from outcrops and high resolution shear wave seismic profiles the chronology is based on luminescence ages 230 th u ages 14 c ages and middle palaeolithic archaeological assemblages the drainage system of the study area developed during the early miocene during the pleistocene up to 170 m of fluvial incision took place a major change in terrace style from strath terraces to cut and fill terraces occurred during the early middle pleistocene before marine isotope stage mis 12 which may correlate with climate deterioration and the onset of glaciation in northern central europe during this time a stable buffer zone was established within which channels avulsed and cut and filled freely without leaving these vertical confines climate was the dominant driver for river incision and aggradation whereas the terrace style was controlled by base level changes during ice sheet growth and decay a major effect of glacio isostatic processes was the post elsterian re direction of the river weser and river leine the middle pleistocene fluvial terraces are vertically stacked indicating a high aggradation to degradation ratio corresponding with a regional base level rise during glacier advance at the beginning of the late pleistocene the terrace style changed from a vertical to a lateral stacking pattern which is attributed to a decrease in accommodation space during glacier retreat the formation of laterally attached terraces persisted into the holocene major incision phases took place during mis 5e 5d 5c and probably early mis 4 early mis 3 and mis 2 lateglacial during mis 5e and the lateglacial the braided river systems changed into meandering rivers indicated by preserved organic rich flood plain and point bar deposits the late pleistocene braided river systems mis 5c to mis 3 are characterized by a high sinuosity which may be a direct effect of an increased downstream gradient after deglaciation when the channel lengthened and the river adjusted to the increased gradient by increasing sinuosity these middle pleniglacial fluvial deposits are unconformably overlain by lateglacial to holocene meandering river deposits which form laterally attached terraces recording millennial scale channel shifts the lack of late pleniglacial deposits might be related to late weichselian forebulge formation

furrowed outcrops of eocene chalk on the lower continental slope offshore new jersey a sea bottom of middle eocene calcareous claystone cut by downslope trending furrows was observed during an alvin dive to the mouth of berkeley canyon on the continental slope off new jersey the furrows are 10 to 50 m apart 4 to 13 m deep linear and nearly parallel in water depths of 2 000 m they have steep walls and flat floors 3 to 5 m wide of fine grained sediment mid range sidescan sonar images show that similarly furrowed surfaces are found on nearby areas of the lower continental slope not associated with canyons the furrows are overlain in places by pleistocene sediments although they show evidence of erosional origin they do not appear to be related to observed structures and their straight parallel pattern is not well understood a general cover of flocky unconsolidated sediments implies that bottom current erosion is not active now

reconstruction of environmental changes during the late glacial and holocene reflected in a soil sedimentary sequence from the lower selenga river valley lake baikal region siberia assessed by lipid molecular proxies abstract sediments of lake baikal and smaller lakes in its surroundings have been frequently used to trace paleoenvironmental changes however these sediments integrate environmental proxies over large areas and the processes leading to alteration of terrestrial signals are not fully understood more specific information can be derived from terrestrial archives such as alternating soil sediment sequences near the village of burdukovo southeast of lake baikal such sequences are accessible along the 5 m high right terrace of the selenga river however terrestrial archives can be associated with degradation of organic matter therefore lipid molecular proxies were applied in the current study to trace environmental and vegetation shifts as well as incorporation and degradation of organic matter alkane and fatty acid molecular proxies as part of the lipid fraction are well known for their diagnostic character to trace sources of organic matter and its degradation several parameters including the carbon preference indices of alkanes and fatty acids indicated a well preservation of the organic matter in the investigated sequence furthermore the organic matter in the c horizons of the terrestrial upper part of the sediments was most likely overprinted by rooting of the plants growing on respective overlaying soils as reflected by the average chain length of fatty acids and alkanes and the relative composition of long chain n alkanes c 25 33 the 3 5 m thick sequence enabled tracing of vegetation shifts the alkane composition argued for changes in the grass dominated vegetation cover within the different phases of the holocene until today whereas a birch and willow dominated deciduous forest vegetation as traced in other archives of the larger baikal area could not be determined in the burdukovo sequence by lipid molecular proxies the scatter in the alkane and fatty acid composition revealed only minor vegetation shifts throughout the holocene nevertheless some changes in the lipid composition indicated a change in the plant community as coniferous trees have often similar alkane patterns to grass vegetation it cannot be excluded that conifers also contributed to a certain degree to the molecular record in the burdukovo sequence the general decrease in the carbon preference index of alkanes since approximately 4 ka bp until recent times further argues for an increasing admixture of coniferous lipids to the record lipid molecular proxies of sediment that formed 2 8 2 6 ka bp revealed the incorporation of deciduous tree derived organic matter most likely originating from birch that grew elsewhere in the catchment of the selenga river the proxies enabled an assessment of site specific vegetation shifts and degradation of organic matter in the soil sediment sequence of the burdukovo area and thus provide more specific information related to a certain area than lacustrine sediments integrating over larger catchments

chronostratigraphy of loess deposits in northeast iran little information is available on the paleoclimate evolution of northeast iran relating to global cold and warm stages the loess paleosol sequences from southern mashhad and kalat e naderi areas were studied to determine the landscape evolution and to set up the first chronological framework for the pleistocene deposits in northeast iran the loess deposits in these areas are less thick up to 12 m and have a more patchy distribution than in the caspian lowland of northern iran infrared stimulated luminescence irsl dating of loess or loess derivatives from the robat e khakestari tappeh salam and deh gheybi sections a and b from southern mashhad as well as kalat e naderi sections a and b in kalat e naderi area provides a more reliable chronological framework for climate and environmental changes taken place over for the time period including the penultimate and last interglacial glacial cycles the robat e khakestari section the kalat e naderi sections a and b and to some extent the tappeh salam section include loess paleosol sequences which are chronologically in excellent agreement with the loess record of the caspian lowland in northern iran the deh gheybi sections a and b include loess like sediments and fluvial deposits that make their interpretation difficult loess accumulated during mis 2 at the robat e khakestari section and at the kalat e naderi sections a and b suggesting a more windy and arid last glacial maximum lgm in northeast iran paleosols correlating most likely with mis 5 were covered by fluvial sediments at the kalat e naderi section a the absence of loess deposits correlating to mis 3 and mis 4 at the robat e khakestari section is very likely to have been caused by fluvial processes and water erosion

field experiment provides ground truth for surface nuclear magnetic resonance measurement a field experiment was conducted in the high plains aquifer central united states to explore the mechanisms governing the non invasive surface nmr snmr technology we acquired both snmr data and logging nmr data at a field site along with lithology information from drill cuttings this allowed us to directly compare the nmr relaxation parameter measured during logging t2 to the relaxation parameter t2 measured using the snmr method the latter can be affected by inhomogeneity in the magnetic field thus obscuring the link between the nmr relaxation parameter and the hydraulic conductivity of the geologic material when the logging t 2 data were transformed to pseudo t2 data by accounting for inhomogeneity in the magnetic field and instrument dead time we found good agreement with t 2 obtained from the snmr measurement these results combined with the additional information about lithology at the site allowed us to delineate the physical mechanisms governing the snmr measurement such understanding is a critical step in developing snmr as a reliable geophysical method for the assessment of groundwater resources citation knight r e grunewald t irons k dlubac y song h n bachman b grau d walsh j d abraham and j cannia 2012 field experiment provides ground truth for surface nuclear magnetic resonance measurement geophys res lett 39 l03304

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

evolution of continental slope gullies on the northern california margin abstract a series of subparallel downslope trending gullies on the northern california continental slope is revealed on high resolution seismic reflection profiles imaging the uppermost 50 m of sediment the gullies are typically 0 m wide and have 1 to 3 m of relief they extend for 10 to 15 km down the slope and merge into larger channels that feed the trinity canyon in the lower half of the 50 m stratigraphic section the gullies increase in both relief and number up section to maxima at a surface 5 to 10 m below the last glacial maximum lowstand surface gully relief increased as interfluves aggraded more rapidly than thalwegs erosion is not evident in the gully bottoms therefore gully growth was probably due to reduced sediment deposition within the gullies relative to that on interfluves as the gullies increased in relief their heads extended upslope toward the shelfbreak at all times a minimum of 10 km of non gullied upper slope and shelf stretched between the heads of the gullies and the paleo shoreline the gullies did not connect with a subaerial drainage network at any time gully growth occurred when the gully heads were in relatively shallow water 200 m paleo water depth and were closest to potential sediment sources we suggest that prior to the last glacial maximum the mad river then within 10 km of the gully heads supplied sediment to the upper slope which fed downslope eroding sediment flows these flows removed sediment from nearly parallel gullies at a rate slightly slower than sediment accumulation from the eel river 40 km to the south the process or processes responsible for gully growth and maintenance prior to the last glacial maximum effectively ceased following the lowstand when sea level rose and gully heads lay in deeper water 300 m water depth farther from potential sediment sources during sea level highstand the mad river is separated from the gully heads by a shelf 30 km wide and no longer feeds sediment flows down the gullies which fill with sediment from the distal eel river approximately one half of the subsurface gullies have no expression on the seafloor because they have completely filled with sediment following the last glacial maximum lowstand of sea level

reconstruction of the late quaternary paleoenvironments of the nussloch loess paleosol sequence germany using n alkane biomarkers abstract this study contributes to the paleoenvironmental reconstruction of the loess paleosol sequence of nussloch germany by using n alkanes as plant leaf wax derived lipid biomarkers we found that n alkane patterns and concentrations in the saalian loess and the last interglacial eemian paleosol of nussloch point to very strong degradation and prevailing deciduous vegetation degradation effects in the overlying paleosols and loess layers are less pronounced and allow for the application of an end member mixing model to estimate vegetation changes semi quantitatively our findings highlight the potential for the interpretation of degradation corrected n alkane ratios n alkane modelling results for loess layers paleosols and an in filled paleochannel dated to 60 32 ka suggest that up to 50 of the n alkanes were derived from deciduous trees or shrubs this finding is in agreement with the abundant occurrence of wood fragments and indicates a highly variable and dynamic landscape dominated by tundra shrubland on the other hand deciduous trees or shrubs did not contribute significantly to the soil organic matter in the late weichselian loess layers and the intercalated gelic gleysols 32 18 ka

incorrect when uncorrected reconstructing vegetation history using n alkane biomarkers in loess paleosol sequences a case study from the saxonian loess region germany abstract this study aims at contributing to the reconstruction of the paleoenvironment of the saxonian loess region by investigating sedimentary n alkanes as plant leaf wax derived biomarkers in two loess paleosol sequences lpss namely the gleina and the rottewitz lpss the weichselian paleosols are characterised by n alkane concentration maxima when compared to the loess layers when this coincides with high odd over even predominances oeps this points not only to increased n alkane input and or production but also to increased n alkane preservation in the soils namely in gleysols with water logged edaphic conditions by contrast the buried cambisols reveal low oeps indicating accelerated degradation under aerobic edaphic conditions the n alkane concentrations in the truncated eemian interglacial paleosol are very low this reflects the removal of the formerly n alkane enriched eemian topsoil low n alkane input into the b t s d horizon subsoil horizon of the eemian luvisol and or strong soil organic matter mineralization four investigated n alkane ratios show distinct variations during the weichselian tempting inferences of vegetation changes in terms of varying contributions of tree shrub derived dominated by n c 27 or n c 29 versus grass derived dominated by n c 31 or n c 33 n alkanes however using the oep as a proxy for degradation and considering that n alkane ratios are prone to degradation effects the above interpretation is very likely incorrect degradation can account for most variability of the n alkane ratios applying an endmember model based on a modern n alkane reference dataset allows estimating the contribution of tree shrub versus grass derived n alkanes semi quantitatively these modelling results suggest that both the gleina and the rottewitz lpss were formed under prevailing grassland minor contributions of trees shrubs are only likely for the gleinaer soil complex in rottewitz lps for the top of a brown gleysol in gleina lps and the holocene soil the weichselian vegetation changes as inferred from the uncorrected n alkane ratios are not confirmed overall the n alkane results support the idea that the gleinaer soil complex in gleina and rottewitz lps respectively are not identical but rather are chronostratigraphic equivalents more favourable regional climatic conditions presumably occurred in the southwesterly exposed rottewitz locality and allowed tree shrub vegetation to grow during favourable periods of the weichselian a major shortcoming of the n alkane biomarker method is that only vegetation changes of deciduous woodland to grassland and vice versa can be reconstructed because coniferous trees exhibit by two to three orders of magnitude lower n alkane concentrations

vegetation and environmental changes during the last interglacial in eastern anatolia turkey a new high resolution pollen record from lake van a high resolution multi proxy record from lake van eastern anatolia derived from a lacustrine sequence cored at the 357 m deep ahlat ridge ar allows a comprehensive view of paleoclimate and environmental history in the continental near east during the last interglacial li we combined paleovegetation pollen stable oxygen isotope delta o 18 bulk and xrf data from the same sedimentary sequence showing distinct variations during the period from 135 to 110 ka ago leading into and out of full interglacial conditions the last interglacial plateau as defined by the presence of thermophilous steppe forest communities lasted ca 13 5 ka from similar to 129 1 115 6 ka bp the detailed palynological sequence at lake van documents a vegetation succession with several climatic phases i the pistacia zone ca 131 2 129 1 ka bp indicates summer dryness and mild winter conditions during the initial warming ii the quercus ulmus zone ca 129 1 1272 ka bp occurred during warm and humid climate conditions with enhanced evaporation iii the carpinus zone ca 1272 124 1 ka bp suggest increasingly cooler and wetter conditions and iv the expansion of pinus at similar to 124 1 ka bp marks the onset of a colder drier environment that extended into the interval of global ice growth pollen data suggest migration of thermophilous trees from refugial areas at the beginning of the last interglacial analogous to the current interglacial the migration documents a time lag between the onset of climatic amelioration and the establishment of an oak steppe forest spanning 2 1 ka hence the major difference between the last interglacial compared to the current interglacial holocene is the abundance of pinus as well as the decrease of deciduous broad leaved trees indicating higher continentality during the last interglacial finally our results demonstrate intra interglacial variability in the low mid latitudes and suggest a close connection with the high frequency climate variability recorded in greenland ice cores c 2015 elsevier b v all rights reserved

isotopic analysis c n and species composition of rodent assemblage as a tool for reconstruction of climate and environment evolution during late quaternary a case study from biśnik cave czestochowa upland poland rodent remains are potentially a powerful tool in paleoecological reconstructions rodents are a worldwide group of mammals inhabiting all climatic zones from arctic tundra to tropical forests some of their representatives have narrow ranges of environmental tolerance while others have cosmopolitan distributions additionally rodent remains are well preserved and numerous in cave sediments and are easily identified to the species level the species composition of rodent assemblage from the specific cave gives valuable data on ecosystem status around the site moreover isotopic composition c n of rodent remains provides information on some environmental factors e g type of vegetation soil activity precipitation and temperature the material for this study was collected from the sediments of the bi nik cave poland the cave is known from its sediment sequence deposited during the middle and late pleistocene and holocene containing a rich collection of the pleistocene fauna remains and archeological artifacts the stratigraphy of the sediment sequence previously was based on archeological findings and several radiometric dates in this study we applied u th dating method to bone collagen rodent tooth enamel and cave bear tooth enamel finally we revised the chronology of sediment sequence from the bi nik cave based on these new data we found significantly higher variability of nitrogen and carbon isotopic composition in the lemming than in the common vole however both species show the same trends in isotopic composition of nitrogen in time at the beginning of the record 15n values were relatively high suggesting intensive soil activity and indirectly mild climate after that from a stratigraphic layer dated to the early wurm glaciation lower 15n values point to lower soil activity deterioration of ecosystem productivity and climate conditions were also confirmed by higher 13c this indicates lower canopy effect and suggests conversion of vegetation around the cave the isotopic record suggests high instability of the environmental conditions during the wurm glaciations with significantly warmer periods before and after the last glacial maximum

landform characterization using geophysics recent advances applications and emerging tools abstract this paper presents an overview of the strengths and limitations of existing and emerging geophysical tools for landform studies the objectives are to discuss recent technical developments and to provide a review of relevant recent literature with a focus on propagating field methods with terrestrial applications for various methods in this category including ground penetrating radar gpr electrical resistivity er seismics and electromagnetic em induction the technical backgrounds are introduced followed by section on novel developments relevant to landform characterization for several decades gpr has been popular for characterization of the shallow subsurface and in particular sedimentary systems novel developments in gpr include the use of multi offset systems to improve signal to noise ratios and data collection efficiency amongst others and the increased use of 3d data multi electrode er systems have become popular in recent years as they allow for relatively fast and detailed mapping novel developments include time lapse monitoring of dynamic processes as well as the use of capacitively coupled systems for fast non invasive surveys em induction methods are especially popular for fast mapping of spatial variation but can also be used to obtain information on the vertical variation in subsurface electrical conductivity in recent years several examples of the use of plane wave em for characterization of landforms have been published seismic methods for landform characterization include seismic reflection and refraction techniques and the use of surface waves a recent development is the use of passive sensing approaches the use of multiple geophysical methods which can benefit from the sensitivity to different subsurface parameters is becoming more common strategies for coupled and joint inversion of complementary datasets will once more widely available benefit the geophysical study of landforms three cases studies are presented on the use of electrical and gpr methods for characterization of landforms in the range of meters to 100 s of meters in dimension in a study of polygonal patterned ground in the saginaw lowlands michigan usa electrical resistivity tomography was used to characterize differences in subsurface texture and water content associated with polygon swale topography also a sand filled thermokarst feature was identified using electrical resistivity data the second example is on the use of constant spread traversing cst for characterization of large scale glaciotectonic deformation in the ludington ridge michigan multiple cst surveys parallel to an 60 m high cliff where broad 100 m synclines and narrow clay rich anticlines are visible illustrated that at least one of the narrow structures extended inland a third case study discusses internal structures of an eolian dune on a coastal spit in new zealand both 35 and 200 mhz gpr data which clearly identified a paleosol and internal sedimentary structures of the dune were used to improve understanding of the development of the dune which may shed light on paleo wind directions

relative hydraulic conductivity in the vadose zone from magnetic resonance sounding brooks corey parameterization of the capillary fringe the magnetic resonance sounding mrs method is used for noninvasive one dimensional assessment of aquifer structures i e for estimating the vertical water content and hydraulic conductivity distributions in the saturated zone so far mrs interpretation schemes for estimating the hydraulic conductivity as a function of the saturation degree in the vadose zone have not been developed in this study we developed a new inversion scheme for mrs to estimate the relative hydraulic conductivity krel which is the ratio of the unsaturated and saturated conductivities the new approach is based on the brooks corey parameterization bcp of the capillary fringe that is the water content distribution of the capillary fringe is considered to be equivalent to the water retention curve in equilibrium state the bcp inversion directly provides estimates of brooks corey parameters from mrs data which allows for the calculation of krel as a function of the saturation degree in doing so the water table must be gi

combination of seismic reflection and constrained resistivity inversion with an application to 4d imaging of the co2 storage site ketzin germany abstracta combination of seismic and geoelectric processing was studied by means of a structurally constrained inversion approach structural constraints were interpreted from the seismic data and integrated into the geoelectric inversion through a local regularization which allowed inverted resistivities to behave discontinuously across defined boundaries this arranged seismic processing and constrained resistivity inversion in a sequential workflow making the generic assumption that the petrophysical parameters of both methods change across common lithostructural boundaries we evaluated the approach using a numerical example and a real data example from the ketzin co2 pilot storage site germany the latter demonstrated the efficiency of this approach for combining 4d seismic and surface downhole geoelectric data in consistence with the synthetic example the constrained resistivity inversions produced clearer delineated images along the boundary between caprock and reservoir formation near the co

the late quaternary loess record of tokaj hungary reconstructing palaeoenvironment vegetation and climate using stable c and n isotopes and biomarkers abstract large areas of southeast europe are covered by pleistocene loess deposits with interbedded palaeosol layers reflecting interglacials or stadials these loess palaeosol sequences are valuable terrestrial archives for continuous palaeoclimatic and palaeoenvironmental information in recent years the traditional paradigm of treeless full glacial palaeoenvironments has increasingly been called into question as there is palynological anthracological and malacological evidence for the continuous presence of trees from loess palaeosol sequences in the carpathian basin this paper aims at contributing to this discussion by applying biogeochemical geophysical and sedimentological methods to a late quaternary loess palaeosol profile at tokaj ne hungary previous studies at the same location have focused on molluscs and charcoal while this study concentrated on stable c and n isotopes and lipid biomarkers long chain n alkanes c 23 c 33 which form major constituents of plant leaf waxes have successfully been used as biomarkers over the last years and allow for a reconstruction of palaeovegetation based on the differentiation of grassland vs shrubs and trees stable carbon isotopes were used to further differentiate between c 3 and c 4 palaeovegetation and stable n isotopes to reconstruct the n cycle and climatic variations magnetic susceptibility ms organic carbon and grain size distribution which may serve as proxies for e g the intensity of pedegenesis weathering and palaeowind strength were measured to complement the biogeochemical results and to establish a pedo and biostratigraphy although the results do not agree in every detail with previous studies there are surprising matches and similarities in the data alkane and stable n isotopic data indicate that pedogenesis occurred under productive fertile steppe grasslands probably in an intensified seasonal climate and during reduced sedimentation two short treeless steppe periods were found between 26 and 12 ka bp however periods characterised by a cooler climate in which trees and shrubs expanded were also found this interpretation is also supported by previous mollusc data that provide evidence for several periods of favourable conditions for tree growth

quantitative paleoenvironmental and paleoclimatic reconstruction using paleosols abstract paleosols fossil soils are preserved throughout the geologic record in depositional settings ranging from alluvial systems to between basalt flows until recently paleosols were studied using primarily qualitative methods in recent years paleopedology has shifted from a largely qualitative field based on comparisons with modern analogues to an increasingly quantitative endeavor some of this change has been a result of applying existing techniques to new materials but many of the innovations have been the result of applying new techniques to new materials including thermodynamic modeling of soil formation isotope geochemistry and applications of empirical relationships derived from modern soils a variety of semi quantitative and quantitative tools has been developed to examine past weathering and pedogenesis and to reconstruct both paleoenvironmental and paleoclimatic conditions at the time that the paleosols formed though it is often not possible to achieve the same temporal resolution as with marine records for paleoclimatic reconstructions proxies based on paleosols are potentially a much more direct means of making paleoclimatic reconstructions because soils form at the earth s surface in direct contact with the atmospheric and climatic conditions at the time of their formation paleoclimatic and environmental properties that may be reconstructed using the new proxies include provenance weathering intensity mean annual precipitation and temperature during pedogenesis nutrient fluxes into and out of the paleosols the atmospheric composition of important gases including co2 and o2 the moisture balance during pedogenesis the soil gas composition reconstructed vegetative covering and paleo altitude

biomarkers in modern and buried soils of semi desert and forest ecosystems of northern iran abstract in northern iran mean annual precipitation and vegetation vary significantly over short distance from a semi desert to a forest biome these ecosystems likely responded differently on past climate changes we here aim at i testing the applicability of biomarkers leave derived n alkanes their stable carbon isotope composition and c and n stable isotopes of soil organic matter in loess derived soils to identify and differentiate past ecosystems and ii elucidating the variability of these biomarkers in palaeosols we sampled modern topsoils and palaeosol horizons within an ecological gradient covering a range in mean annual precipitation from 200 to 750 mm from the kopet dag semi desert to the hyrcanian forest on the footslopes of the alborz mountains c org n 13 c org 15 n and n alkanes and their compound specific 13 c were analyzed to characterize organic matter composition and sources in modern soils a systematic increase in c org and n was observed with precipitation the 15 n decreased from about 6 to 4 pointing to systematically more degraded organic matter in semi desert soils the leave wax specific ratio of nc 31 nc 33 nc 27 nc 29 n alkanes was 1 for semi desert soils and 13 c org showed no systematic trend in this gradient in loess and palaeosol profiles contents of c org n and n alkanes dropped about a factor 10 compared to modern soils the n alkane ratio and 15 n ratios remained on comparable levels as did the compound specific 13 c in n alkanes however bulk 13 c org was altered from about 27 in modern soil to 23 in loess palaeosols systematically higher c org and n values were observed in palaeo topsoils compared to loess and subsoil stable c isotopes varied rather unsystematically within loess palaeosol sequences while 15 n revealed trends within palaeosols however in contrasting directions with palaesol depth the temporal average n alkane ratio for all palaeosol horizons of one site systematically followed the modern precipitation gradient indicating that in all periods of soil formation a climatic gradient developed

the late pleistocene belotinac section southern serbia at the southern limit of the european loess belt environmental and climate reconstruction using grain size and stable c and n isotopes the belotinac loess section is one of the southernmost loess paleosol environmental archives for the late quaternary in serbia the climate at this site is intermediate between the continental and the mediterranean realms which makes this loess archive potentially highly sensitive to past climatic changes this paper presents new insights into the paleoenvironmental history during the last glacial period in southern serbia using grain size and isotope proxy data the grain size parameters from the belotinac section reveal variations in the paleowind dynamics and weathering intensity and suggest the nearby valley of the ju na morava river as an important source of aeolian sediments in this area based on a multiproxy dataset alternating phases of weak interstadials and phases of enhanced loess deposition at this site were identified nitrogen isotope data suggest that during marine isotope stage 3 ecosystems of high biomass productivity and rather open n cycles prevailed during marine isotope stage 2 productivity was reduced and the n cycle was more strongly closed probably due to a shorter growing season and more pronounced temperature decline carbon isotope data indicate a possible contribution of c4 plants to the holocene vegetation but not to the glacial and interstadial ecosystems of the late pleistocene changes in atmospheric co2 level are not reflected in the carbon isotope record these findings are discussed in the light of paleoclimate proxy datasets from the morava river valley and carpathian basin as well as through comparison of carbon isotope records from loess sections in se central europe and in the rhine valley two different loess provinces exist in terms of glacial interglacial humidity changes a province of glacial drying and a province of glacial humidification the first includes loess sites under more oceanic influence where loess 13c records indicate humid interglacials and interstadials and relatively drier glacial periods the second includes the loess sites of the carpathian basin and especially the southern serbian loess area of belotinac where loess 13c records indicate more intensive aridity during interglacials but a reduced soil moisture deficit and a more humid climate due to lower evapotranspiration in interstadials and even more in glacial periods

cyanobacterial diversity and toxicity of biocrusts from the caspian lowland loess deposits north iran abstract biocrusts and adjacent sediments were collected from the so called loess plateau of northern iran and the loess deposits on the foothills of alborz mountains the mineralogical and granulometric analyses characterized sediments as quartz rich clayey or sandy silts cyanobacterial diversity colony morphology and grain stabilization were studied by light and scanning electron microscopy which showed glue like layers of cyanobacterial eps and dense networks of filamentous cyanobacteria immobilizing finer and bigger grains respectively amorphous tuft and globular cyanobacterial colony structures were also detected 15 cyanobacterial genera were identified in the biocrust samples including microcoleus vaginatus as the common species in all samples aphanocapsa aphanothece calothrix chroococcus chroococcidiopsis cyanosarcina hassallia homeothrix nostoc oculatella schizothrix scytonema tolypothrix and trichocoleus two biocrust samples showed traces of toxicity in a protein phosphatase inhibition assay targeting microcystins and similarly acting compounds the artemia salina assay revealed an elevated toxic response in one sample

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

generation of 3 d hydrostratigraphic zones from dense airborne electromagnetic data to assess groundwater model prediction error we present a new methodology to combine spatially dense high resolution airborne electromagnetic aem data and sparse borehole information to construct multiple plausible geological structures using a stochastic approach the method developed allows for quantification of the performance of groundwater models built from different geological realizations of structure multiple structural realizations are generated using geostatistical monte carlo simulations that treat sparse borehole lithological observations as hard data and dense geophysically derived structural probabilities as soft data each structural model is used to define 3 d hydrostratigraphical zones of a groundwater model and the hydraulic parameter values of the zones are estimated by using nonlinear regression to fit hydrological data hydraulic head and river discharge measurements use of the methodology is demonstrated for a synthetic domain having structures of categorical deposits consisting of sand silt or clay it is shown that using dense aem data with the methodology can significantly improve the estimated accuracy of the sediment distribution as compared to when borehole data are used alone it is also shown that this use of aem data can improve the predictive capability of a calibrated groundwater model that uses the geological structures as zones however such structural models will always contain errors because even with dense aem data it is not possible to perfectly resolve the structures of a groundwater system it is shown that when using such erroneous structures in a groundwater model they can lead to biased parameter estimates and biased model predictions therefore impairing the model s predictive capability

multivariate analysis of cross hole georadar velocity and attenuation tomograms for aquifer zonation 1 we have investigated the potential of combining cross hole georadar velocity and attenuation tomography as a method for characterizing heterogeneous alluvial aquifers a multivariate statistical technique known as k means cluster analysis is used to correlate and integrate information contained in velocity and attenuation tomograms cluster analysis allows us to identify objectively the major common trends in the tomographic data and thus to reduce the information to a limited number of characteristic parameter combinations the application of this procedure to two synthetic data sets indicates that it is a powerful tool for converting the complex relationships between the tomographically derived velocity and attenuation structures into a lithologically and hydrologically meaningful zonation of the probed region in addition these synthetic examples allow us to evaluate the reliability of further petrophysical parameter estimates we find that although absolute values of the tomographically inferred petrophysical parameters often differ significantly from the actual parameters the clustering approach enables us to reliably identify the major trends in the petrophysical properties finally we have applied the approach to a cross hole georadar data set collected in a well studied alluvial aquifer a comparison of the clustered tomographic section with well log data demonstrates that our approach delineates the hydrostratigraphic zonation

traveltime inversion of vertical radar profiles traveltimes of direct arrivals in vertical radar profiles vrps are tomographically inverted to estimate the earth s electromagnetic em velocity between a surface transmitter and a downhole receiver we determine the 1d interval velocity model that best fits the first arrival traveltimes by using a weighted damped least squares inversion scheme we assess the accuracy of the velocity model using synthetic traveltimes from a known velocity distribution model simulating an unconfined aquifer the inverted velocity profile closely matched the velocity profile of the input model in the synthetic examples using vertical radar profile data from an unconfined aquifer near boise idaho we inverted traveltimes to obtain velocity estimates at the well location the velocity change at a depth of 2 0 m corresponds well with the measured depth to the water table of 1 95 m and at depths between 2 and 18 m the velocities ranged between 0 06 and 0 1 m ns our estimates approximately match the velocity distribution determined from neutron derived porosity logs at depths greater than about 2 m an important function of inverse methods is to assess quantitatively and qualitatively the uncertainty of inverted velocity estimates we note that the velocity values in the upper and lower parts of the inverted model are not as well constrained compared to those between the depths of 4 and 13 m from the model resolution and model covariance matrices of the real data inversion we determine theuncertainty in ourvelocity model leading to more reliable interpretations of the subsurface

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

summer monsoon intensity controls c4 c3 plant abundance during the last 35 ka in the chinese loess plateau carbon isotope evidence from bulk organic matter and individual leaf waxes the natural abundance of c3 and c4 plants is affected by multiple environmental factors including temperature moisture balance and atmospheric pco2 the relative importance of these factors is a subject of considerable debate and may vary in different natural ecosystems previous studies generally focus on single loess sequences in the chinese loess plateau and conflicting conclusions on c4 c3 have been reached when studying carbon isotope ratios in carbonate and organic matter in this paper we report a comprehensive carbon isotopic characterization of total organic carbon toc and individual higher plant leaf waxes from five loess sequences spanning the last 35 ka from the chinese loess plateau clp the five coring sites encompass large gradients of annual mean temperature 9 2 13 9 c and precipitation 402 673 mm allowing us to assess the controlling mechanisms on c4 c3 plant ratios glacial interglacial sequences provide carbon isotope data for comparison with other climatic and environmental proxies such as lithology and magnetic susceptibility our results demonstrate that increased c4 c3 ratios are positively correlated with higher temperature and increased summer rainfall which characterize stronger summer monsoon in all five sites we conclude c4 abundance increases from the last glacial to the holocene in response to greater monsoon activity and that the c4 expression is suppressed in the cold and drier intervals

a preliminary reconstruction of the paleoecological and paleoclimatic history of the chinese loess plateau from the application of biomarkers abstract this study provides a preliminary reconstruction of paleoecological and paleoclimatic history over the central chinese loess plateau clp during the last 8 1 ma based on biomarker records from the earliest of the chaona stratigraphic section throughout the section we found variations in n alkane and n alkan 2 one distributions and dramatic changes in six other biomarker proxies 1 n alkanes c27 c29 c31 c33 ratios 2 n alkanes c27 c31 ratios 3 cpi carbon preference index values for cpi h alk 4 values for cpi h ket 5 n alkane mean chain lengths acl alk and 6 n alkan 2 ones c29 c31 ratios the c29 n alkanes dominate the red clay sediments with little variability indicating that trees dominated the clp and that the climate was relatively stable and less variable during the 8 1 2 6 ma period in contrast the c31 n alkanes dominate the loess paleosol sediments and biomarkers vary with relatively greater amplitude and higher frequency indicating that grasses dominated the clp and the climate was more arid and variable these biomarker records chronicle a drying and cooling trend on the clp since 4 ma these records can be further divided into four stages with boundaries around 5 6 3 8 and 2 6 ma indicating that the clp vegetation and climate experienced four evolutionary phases broadly consistent with those inferred from other available proxy data

holocene vegetation history and sea level changes in the se corner of the caspian sea relevance to sw asia climate the palynological investigation of core tm 27 7 m long taken in a dried out lagoon reveals both holocene vegetation history in the north eastern foothills of the alborz mountains and past water level changes of the caspian sea cs the delay in woodland expansion at the beginning of the holocene which is typical of eastern turkey the iranian plateau and recorded in the cs south basin is only weakly felt as the region is close to glacial refugia of trees the succession of the main trees out of their refugia has been established as deciduous quercus carpinus betulus parrotia persica and fagus orientalis pterocarya fraxinifolia presenting therefore close affinities to south european interglacials of the early pleistocene this suggests a similarity in climate a pterocarya decline is observed after ad 495 the studied region is close to the easternmost tree distribution this could explain why it has been affected earlier than elsewhere in the northern alborz and the caucasus in addition human activities during the sasanian empire and the subsequent drying of the climate contributed to weakening the spread of this tree a maximal sea level occurs in the first part of the holocene from 10 6 to 7 2 cal ka it is suggested that the cs levels were significantly influenced by the monsoon precipitations over the western himalayas via the uzboy inflow this is followed by low levels from 7 2 to 3 5 cal ka with a minimum at 3 9 cal ka the neocaspian period should be considered a biozone rather than a chronozone as the environmental conditions reconstructed from dinocyst assemblages are different in shallow shelf waters and in the deep basins

improved hydrogeophysical characterization using joint inversion of cross hole electrical resistance and ground penetrating radar traveltime data appropriate regularizations of geophysical inverse problems and joint inversion of different data types improve geophysical models and increase their usefulness in hydrogeological studies we have developed an efficient method to calculate stochastic regularization operators for given geostatistical models the method which combines circulant embedding and the diagonalization theorem of circulant matrices is applicable for stationary geostatistical models when the grid discretization in each spatial direction is uniform in the volume of interest we also used a structural approach to jointly invert cross hole electrical resistance and ground penetrating radar traveltime data in three dimensions the two models are coupled by assuming at all points that the cross product of the gradients of the two models is zero no petrophysical relationship between electrical conductivity and relative permittivity is assumed but is instead obtained as a by product of the inversion the approach has been applied to data collected in a u k sandstone aquifer in order to improve characterization of the vadose zone hydrostratigraphy by analyzing scatterplots of electrical conductivity versus relative permittivity together with petrophysical models a zonation could be obtained with corresponding estimates of the electrical formation factor the water content and the effective grain radius of the sediments the approach provides greater insight into the hydrogeological characteristics of the subsurface than by using conventional geophysical inversion methods

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

loess chronology of the caspian lowland in northern iran the loess palaeosol sequences of the caspian lowland in northern iran provide detailed archives of climate and environmental change showing a close relationship to global cooling and warming trends for the quaternary period the magnitude of these changes is under discussion owing to uncertainties in the chronologies for individual sites a chronological frame was set up for the last glacial loess record for three upper pleistocene key sections by infrared optically stimulated luminescence irsl in the caspian lowland irsl dating gives reliable ages for sediments covering at least the past 60 ka however for sediments older than 60 ka a significant age underestimation is likely the first strongly developed buried bt bwt horizons or pedocomplexes at the three sections under study correlate most likely with the last interglacial mis 5 at least four periods of increased sediment accumulation were determined for the last glacial period intercalated by periods of weak soil formation the loess palaeosol sequences in northern iran recorded coeval and similar major climatic changes as in south eastern central europe and central asia

reconstruction of postglacial to early holocene vegetation history in terrestrial central europe via cuticular lipid biomarkers and pollen records from lake sediments high resolution environmental reconstruction for central european terrestrial settings is commonly based on sediment records that provide the pollen spectra used for reconstruction of vegetation development alternatively complementary algal insect or zooplankton assemblages and or carbonate 18 o isotope profiles are investigated in this study vegetation development and inferred climate evolution were documented on a decadal to centennial scale by analysis of land plant cuticular lipids accumulated in lake sediments wax lipids derived from land plant leaves and blades are source diagnostic and highly resistant to degradation their aerodynamic properties favor short distance eolian transport but they are less affected by possible long distance transportation that complicates pollen analysis the late glacial to holocene sedimentary record of lake steisslingen southwestern germany was investigated by palynological and geochemical means tundra type pioneer vegetation consisting predominantly of grasses and herbs is dominated by nc31 alkanes whereas pioneer birch forest yields preferentially nc27 alkanes establishment of a pine assemblage is recognizable by elevated nc29 and nc31 leaf wax alkanes and the diversification of deciduous forests in the holocene is marked by nc29 dominance lipid geochemistry and palynology resolve decadal excursions such as the mid younger dryas event centennial climate trends with pronounced and rapid changes at the oldest dryas bolling allerod younger dryas and younger dryas preboreal transitions are consistently reflected by molecular and palynological proxy data the demonstrated suitability of an independent molecular proxy in paleoenvironmental studies provides new perspectives in high resolution climate reconstruction

importance of biological loess crusts for loess formation in semi arid environments the essential abiotic components for loess formation are material dust atmospheric circulation wind suitable surface conditions for the trapping of aeolian material and for the subsequent development of typical loess sedimentary structures in spite of the world wide distribution of loess deposits knowledge of the processes of dust accumulation and its transformation to mature loess sediment is still inadequate loess accumulation appears greatest during the most arid periods and in semi arid regions biological crusted surfaces bcs are of potentially great importance in loess formation especially in semi arid regions bcs are highly specialized extremophile communities and apparently play an important role in atmospheric dust trapping and erosion prevention results indicate that cyanobacterial strains isolated from current carpathian basin loess exhibit specific morphological and eco physiological characteristics that play a key role in loess formation warranting adoption of the new term biological loess crusts blc a model of the influence of cyanobacterial blc life strategies on loess formation explains trapping accumulation and preservation as well as loess texture and structure this potential significance of blc in the accumulation and preservation of loess sediments may be considered as a model suitable model database for recognition of bioorganic modification of geological strata mycosporine and scytonemin pigments can serve as blc biomarkers elucidating their role in soil evolution and in aiding paleoclimatic paleoenvironmental and paleovegetation reconstructions

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

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

subglacial till formation sedimentary characteristics and classification we review the major subglacial till forming processes as presently understood by glacial researchers and define the parameters within which tills are produced and reconcile them with sedimentary end members processes of deformation flow sliding lodgement and ploughing coexist at the base of temperate glacier ice and act to mobilize and transport sediment and deposit it as various end members ranging from glacitectonically folded and faulted stratified material to texturally homogeneous diamicton the dominance of any one subglacial process varies both spatially and temporally giving rise to the possibility that a till or complex till sequence contains a superimposed signature of former transportation deposition at the ice bed interface we recommend that while glacial geologists and geomorphologists should be able to recognize the sedimentary imprints of various subglacial processes genetic fingerprinting of subglacial tills should be less process specific and till classification must reflect the range of products encompassed by the subglacial till production continuum glacial geologists can presently unequivocally identify a glacitectonite rock or sediment that has been deformed by subglacial shearing deformation but retains some of the structural characteristics of the parent material b subglacial traction till sediment deposited by a glacier sole either sliding over and or deforming its bed the sediment having been released directly from the ice by pressure melting and or liberated from the substrate and then disaggregated and completely or largely homogenised by shearing and support the theoretical case for c melt out till sediment released by the melting of stagnant or slowly moving debris rich glacier ice and directly deposited without subsequent transport or deformation because observations on contemporary glaciers reveal that their beds are most likely to be mosaics of deformation and sliding and warm based and cold based conditions the patterns of which change temporally and spatially it is extremely unlikely that subglacial till end members in the geological record will be anything but hybrids produced by the range of processes operative in the subglacial traction zone

velocity variations and water content estimated from multi offset ground penetrating radar the common midpoint cmp processing technique has been shown to be effective in improving the results of ground penetrating radar gpr profiling when radar data are collected with the cmp multioffset geometry stacking increases the signal to noise ratio of subsurface radar reflections and results in an improved subsurface image an important aspect of cmp processing is normal moveout velocity analysis our objectives are to show the effect of multiple velocity analyses on the stacked radar image and particularly to demonstrate that this velocity information can also be used to determine subsurface water content most gpr surveys are very limited in spatial extent and assume that within the survey range radar velocity structure in the shallow subsurface can be adequately approximated by a single velocity function in data processing in this study we show that variation in radar velocity can be quite significant and that the stacked profile improves as the number of velocity analysis locations is increased interval velocities can be calculated from the normal moveout velocities derived in the cmp velocity analysis with some reasonable assumptions about subsurface conditions necessary for radar propagation interval velocity can be converted to an estimate of volumetric water content therefore by collecting gpr data in the multioffset cmp geometry not only is the radar profile improved but it also allows for an interpretation of subsurface variation in water content we show the application of these techniques to multioffset gpr data from the chalk river test area operated by atomic energy of canada limited