petrographic features of tills as a tool in solving stratigraphical and palaeogeographical problems a case study from central eastern poland abstract lithostratigraphical correlation of tills in poland is most often carried out on the basis of petrographic analysis of fine gravel fraction 20 mm of tills from central eastern poland samples were taken in the sites the stratigraphy of which was previously well recognized based on the proportions between erratics derived from different regions of fennoscandia and their calculated theoretical boulder centres two main lithotypes of tills of middle pleistocene age are distinguished a and b lithotype a is assigned to elsterian the south polish complex sanian 2 mis 12 lithotype b is considered to be characteristic of saalian the middle polish complex within litothype b there are distinguished two sublithotypes b 1 and b 2 which can be linked to the advances of fennoscandian ice sheet during mis 8 older saalian and mis 6 younger saalian the results of the research reveal that the changes of erratics assamblages in tills deposited during the successive ice sheet advances in central eastern poland reproduce a trend that has been ascertained earlier in the sites located approx 200 km further west in central poland and 600 km in northern germany where their stratigraphic position is not so clear cut the general trend of changes in all three areas is the same but the petrographic composition of tills of the same age varies along the former glacier front the results indicate the advisability of using a modified more appropriate methodology in the analysis of indicator erratics occurring in tills we recommend that the calculation of theoretical boulder centres tbc should be based only on crystalline igneous and metamorphic erratics they are strongly resistant ones therefore the lithostratigraphic correlation of tills of various weathering degree is more reliable

using fractal crustal magnetization models in magnetic interpretation1 evidence from borehole susceptibility logs and the spectral analysis of aeromagnetic data suggests that the three dimensional distribution of magnetization within the crust can be described as fractal this property can be exploited in magnetic interpretation methods which explicitly require statistical information on the spatial variation of magnetization specifically we address the problem of magnetic source depth estimation through downward continuation and gridding aeromagnetic survey data using the method of kriging when magnetic data are continued downwards the depth at which the power spectrum flattens out the white depth can be taken to be an estimate of the top of the source distribution this procedure assumes that individual sources are uncorrelated with each other taking into account the correlation of the magnetization using a fractal description leads to a reduction in this depth estimate gridding of randomly distributed magnetic measurements using kriging requires an estimate of the covariance of the data compared with the assumption of a white uncorrelated magnetization distribution using fractal covariances for kriging produces gridded estimates which more closely reflect the statistics of the underlying magnetization process and produce maps with a justifiable degree of smoothness

impact of bedrock surface topography on spatial distribution of quaternary sediments and on the flow pattern of late weichselian glaciers on the east european craton russian plain this paper presents the first high quality maps of the bedrock surface topography and the quaternary sediment distribution for the late weichselian glaciation area on the east european craton eec and the reasoning behind the estimated sediment distribution geographic information system gis based three dimensional model of the bedrock surface topography the current digital terrain model dtm and the ice flow pattern of the last glaciation provided the main source data for the analyses and interpretations in the current continental area of the western eec which was covered by the last scandinavian ice sheet sis the bedrock lies overwhelmingly 85 above the contemporary sea level with an average altitude of 54 m above sea level the topography of the bedrock surface is very well reflected in the current topography and an 80 m difference in the ice bed surface altitudes results in the topographic focusing of the ice flow and thus all late weichselian ice streams were accommodated to the depressions in the subglacial surface such depressions are characterised by a thin 10 m layer of sediment with one till bed just 50 m upslope from the bottom of the depressions the thickness of the sediment increases two to threefold and comprises five or more till layers indicating relief enhancement through subsequent glaciations the average calculated thickness of the quaternary deposits in the study area was 49 m and the total volume of sediments was 20 280 km3

southern laurentide ice lobes were created by ice streams des moines lobe in minnesota usa abstract regional mapping in southern minnesota has illuminated a suite of landforms developed by the des moines lobe that delimit the position of the lobe at its maximum and at lesser readvances the ice lobe repeatedly advanced discharged its subglacial water and subsequently stagnated recent glaciological research on antarctic ice streams has led some glacial geologists to postulate that ice streams drained parts of the marine based areas of the laurentide ice sheet i postulate that such ice streams may develop in land based areas of an ice sheet as well and that the des moines lobe 200 km wide and 900 km long was an outlet glacier of an ice stream it appears to have been able to advance beyond the laurentide ice sheet as long as adequate water pressure was maintained however the outer part of the lobe stagnated because subglacial water that facilitated the flow was able to drain away through tunnel valleys stagnation of the lobe is not equivalent to stoppage of the ice stream because ice repeatedly advanced into and onto the stagnant margins stacking ice and debris similar landforms are also seen in other lobes of the upper midwestern united states

last glacial maximum in poland abstract the last glacial maximum lgm in poland is represented by the leszno phase and occurred after 21 ka radiocarbon years in turn the deglacial poznan phase is estimated at 18 4 ka the pomeranian phase at 15 2 ka the gardno phase at about 14 0 13 8 ka the slupsk bank phase at 13 5 13 2 ka and the southern middle bank phase at 12 7 12 5 ka bp the ice sheet limit at lgm was not synchronous everywhere in poland but occurred as several major and minor ice lobes that reflected a stream like structure of the ice body that radiated southwards from the baltic basin meltwater runoff during the lgm created a complex system of sandur trains and ice marginal spillways with numerous intervening proglacial lakes

a multiproxy study of a basal till a time transgressive accretion and deformation hypothesis a two part basal till at knud strand denmark reveals a uniform fabric pattern and strength petrographical composition and clay mineralogy the nature of the contact with the underlying sediments ductile deformation structures partly intact soft sediment clasts small meltwater channels and thin horizontal outwash stringers dispersed in the till indicate both bed deformation and basal decoupling by pressurised subglacial water a time transgressive model is suggested to explain the lack of vertical gradation in till properties in which debris released from the active ice sole is sheared in a thin zone moving upward as till accretion proceeds it is suggested that although strain indicators occur throughout the entire till thickness the deformation at any point of time encompassed the uppermost part of the till only allowing preservation of fragile clasts below the substantial thickness of the till up to 6 m coupled with a much smaller by more than one order of magnitude inferred thickness of the deforming bed suggests that the bulk of till material was transported englacially prior to deposition the lack of petrographical gradation in the till is attributed to effective mixing and homogenisation of material along the ice flow path copyright 2004 john wiley sons ltd

a strength criterion for frozen clay considering the influence of stress lode angle to investigate the influence of stress lode angle on frozen soil a series of directional shear tests was conducted on artificial frozen clay at three temperatures 6 10 and 15 c and five st

southwest scandinavia 40 15 kyr bp palaeogeography and environmental change twelve palaeogeographical reconstructions illustrate environmental changes at the southwest rim of the scandinavian ice sheet 40 15 kyr bp synchronised land sea and glacier configurations are based on the lithostratigraphy of tills and intertill sediments dating is provided by optically stimulated luminescence and calibrated accelerator mass spectrometry radiocarbon an interstadial sequence ca 40 30 kyr bp with boreo arctic proglacial fjords and subarctic flora and occasional glaciation in the baltic was succeeded by a last glacial maximum sequence ca 3020 kyr bp with the closure of fjords and subsequent ice streams in glacial lake basins in kattegat and the baltic steadily flowing ice from sweden bordered the norwegian channel ice stream a deglaciation sequence ca 20 15 kyr bp indicates the transgression of arctic waters retreat of the swedish ice and advance of baltic ice streams succeeded by a return to interstadial conditions when ameliorated ice free conditions prevailed in maritime regions glaciers advanced through the baltic and when interstadial regimes dominated the baltic glaciers expanded off the norwegian coast the largest glacier extent was reached in the north sea around 29 kyr bp about 22 kyr bp in denmark and ca 18 kyr bp in the baltic our model provides new data for future numerical and qualitative landform based models copyright c 2003 john wiley sons ltd less

continental scale transport of sediments by the baltic ice stream elucidated by coupled grain size and nd provenance analyses abstract we introduce a methodology for determining the transport distance of subglacially comminuted and entrained sediments we pilot this method on sediments from the terminal margin of the baltic ice stream the largest ice stream of the fennoscandian ice sheet during the last glacial maximum a strong correlation r2 0 83 between the end and latitudes of circum baltic river sediments enables us to use end as a calibrated measure of distance the proportion of subglacially transported sediments in a sample is estimated from grain size ratios in the silt fraction

palaeo ice streams abstract the location and behaviour of ice streams is one of the most important controls on ice sheet configuration and stability in order to reconstruct former ice sheets we need to know ice stream location and timing once identified the beds of palaeo ice streams provide an unprecedented opportunity to glean information about their basal environment something that remains very difficult under contemporary ice streams this paper represents the first synthesis and discussion of palaeo ice stream research from a variety of former ice sheets and includes new insights relating their configuration and activity to the evidence they leave behind the ambiguous use of the term ice stream is addressed and four possible configurations for ice streams are presented diagnostic landforms and landform assemblages that we would expect an ice stream to produce are discussed and the temporal context of bedform generation is described as either a rubber stamped or smudged bedform imprint resulting from isochronous or time transgressive landform generation in particular we focus on the configuration of terrestrially terminating ice streams for which there are no modern analogues technological advances in marine geophysics are helping to generate a convergence of interest between antarctic glaciology and palaeo glaciology it is suggested that investigations around the fringes of contemporary ice sheets i e west antarctica can provide evidence that directly links the geomorphological record of palaeo ice streams with their contemporary counterparts in addition computational advances and modelling adaptations have permitted the incorporation of ice streams within ice sheet models we argue that data from palaeo ice stream beds are invaluable to ice sheet stream modelling experiments and will help us understand ice stream operation and the linkages between climate perturbations and both palaeo and contemporary ice sheets

multifractal analysis and modeling of rainfall and river flows and scaling causal transfer functions river flows have been known to be scaling for over 40 years and scaling notions have developed rapidly since the 1980s using the framework of universal multifractals and time series of rainfall and river runoff for 30 french catchments basin sizes of 40 km 2 to 200 km 2 from 1 day to 30 years we quantify types and extent of the scaling regimes for both flow and rain series we observed a scale break at roughly 16 days which we associate with the synoptic maximum the time scale of structures of planetary spatial extent for the two scaling regimes in both series we estimate the universal multifractal parameters as well as the critical exponents associated with multifractal phase transitions using these exponents we perform causal multifractal time series simulations and show how a simple linear scaling transfer function can be used to relate the low frequency rainfall series to the corresponding river flow series the highfrequency regime requires nonlinear transforms

depth estimation from the scaling power spectrum of potential fields summary depth estimation from potential field power spectra requires a realistic assumption of the statistical properties of the source distributions density and susceptibility distributions in the earth s crust exhibit a long range dependence which is adequately described by scaling random fields with a spectral density proportional to some power of the wavenumber the theoretical power spectrum for a half space model of scaling sources explains the shape of observed power spectra of real potential field data very well minimizing the misfit between the model and the observed power spectrum yields an estimate for the depth to the top of the sources after demonstrating this approach on synthetic magnetic data we reinterpret power spectra of gravity and aeromagnetic data from utah hawaii and saskatchewan finding depth values that differ significantly from earlier interpretations all three power spectra are best explained by source distributions starting at surface level even the power spectrum from an aeromagnetic survey of a sedimentary basin with virtually non magnetic basin fill in the latter case a priori information on the intensity and the scaling exponent of the field caused by the basement had to be included to obtain an approximate estimate of the basin depth in general potential field power spectra are dominated by scaling properties of their source distributions and contain only limited depth information

toward a full multiscale approach to interpret potential fields the way potential fields convey source information depends on the scale at which the field is analysed in this sense a multiscale analysis is a useful method to study potential fields particularly when the main field contributions are caused by sources with different depths and extents our multiscale approach is built with a stable transformation such as depth from extreme points its stability results from mixing in a single operator the wavenumber low pass behaviour of the upward continuation transformation of the field with the enhancement high pass properties of n order derivative transformations so the complex reciprocal interference of several field components may be efficiently faced at several scales of the analysis and the depth to the sources may be estimated together with the homogeneity degrees of the field in order to estimate the source boundaries we use another multiscale method the multiscale derivative analysis which utilizes a generalized concept of horizontal derivative and produces a set of boundary maps at different scales we show through synthetic examples and application to the gravity field of southern italy that this multiscale behaviour makes this technique quite different from other source boundary estimators the main result obtained by integrating multiscale derivative analysis with depth from extreme points is the retrieval of rather effective information of the field sources horizontal boundaries depth structural index this interpretative approach has been used along a specific transect for the analysis of the bouguer anomaly field of southern apennines it was set at such scales so to emphasize either regional or local features along the transect two different classes of sources were individuated the first one includes a broad deep source with lateral size of 45 50 km at a depth of 13 km and having a 0 5 structural index the second class includes several narrower sources located at shallowest depths ranging from 3 6 km with lateral size not larger than 5 km and structural indexes ranging from 1 1 5 within a large scale geological framework these results could help to outline the mean structural features at crustal depths

deposit density of tungsten polymetallic deposits in the eastern nanling metallogenic belt china abstract estimation of the number of undiscovered mineral deposits is critical for quantitatively assessing mineral resources traditional statistic methods are limited to analyzing the spatial distribution of mineral deposits which can be considered spatial point processes because of complexity self organized criticality and singularity properties in this study spatial statistic methods including average nearest neighbor distance fry analysis k function and fractal analysis are used to quantify the agglomeration and fractal characteristics of tungsten polymetallic deposits in the eastern nanling metallogenic belt enmb local singularity analysis for w sn mo bi be association is used to delineate the permissive areas for tungsten deposits the results show that tungsten polymetallic deposits are distributed with fractal clustering in region while at random in permissive areas the summary function comparison shows that the k function analysis based on a heterogeneous process may be more robust than on a homogeneous k function when quantifying the distribution of mineral deposits especially for endogenic deposits furthermore the concept of mineral equivalent is introduced in this study and the combination of mineral equivalent and radial density model for mineral deposits mitigates the problem of ignoring the proportion of large medium and small sized deposits in the uniform deposit density model the estimation results indicate that there are still good future prospects in this region this research not only extends the application of spatial statistics in quantifying the spatial distribution of mineral deposits but also provides a new approach to estimate the number of undiscovered mineral deposits

till stratigraphy and sedimentology at the margins of terrestrially terminating ice streams case study of the western canadian prairies and high plains complex glacigenic sediment sequences arranged in large arcuate assemblages and demarcating the lobate termini of fast ice flow corridors in western canada represent the terrestrial equivalents of the trough mouth fans of the marine palaeo ice stream record intensive sedimentological and stratigraphic investigations at a regional scale are employed in the interpretation of thick units or sequences of diamicton and two depositional scenarios are proposed first glacier marginal till thickening and the stacking of till wedges takes place in areas where an ice stream margin was stationary for short periods of time stacks of subglacial traction tills potentially record annual sub marginal incremental thickening at ice stream margins especially in areas where densely spaced recessional push moraines appear to record seasonal climatic forcing second proglacial lake and valley infilling with glacilacustrine rhythmites and mass flow diamictons is associated with the advection of sub marginal till into preglacial bedrock depressions and records ice stream marginal oscillations and debris influx into discontinuous proglacial lakes which act as subaqueous sediment sinks for materials that would otherwise have been used to construct sub marginal till wedges and moraines glacial overriding modifies the deposits produced in both scenarios through deformation and the dislocation and entrainment of bedrock and sediment rafts at the margins of bedrock valley walls resulting in the widespread development of glacitectonites and megablocks the occurrence of the thickest deposits as preglacial valley fills may be significant in groundwater siphoning away from subglacial deforming layers and the promotion of sticky spots

formation of subglacial till under transient bed conditions deposition deformation and basal decoupling under a weichselian ice sheet lobe central poland a multi proxy approach involving a study of sediment architecture grain size grain roundness and crushing index petrographic and clay mineral composition till fabric and till micromorphology was applied to infer processes of till formation and deformation under a weichselian ice sheet at kurzetnik poland the succession consists of three superposed till units overlying outwash sediments deformed at the top the textural characteristics of tills vary little throughout the till thickness whereas structural appearance is diversified including massive and bedded regions indicators of intergranular bed deformation include overturned attenuated folds boudinage structures a sediment mixing zone grain crushing microstructural lineations grain stacking and high fabric strength lodgement proxies are grooved intra till surfaces ploughing marks and consistently striated clast surfaces basal decoupling by pressurized meltwater is indicated by undisturbed sand stringers sand filled meltwater scours under pebbles and partly armoured till pellets it is suggested that the till experienced multiple transitions between lodgement deformation and basal decoupling cumulative strain was high but the depth of time transgressive deformation much lower centimetre range than the entire till thickness ca 2 m at any point in time consistent with the deforming bed mosaic model throughout most of ice overriding porewater pressure was high in the vicinity of glacier floatation pressure indicating that the substratum consisting of 11 m thick sand was unable to drain subglacial meltwater sufficiently

global and local multiscale analysis of magnetic susceptibility data geophysical well logs often show a complex behavior which seems to suggest a multifractal nature multifractals are highly intermittent signals with distinct active bursts and passive regions which cannot be satisfactorily characterized in terms of just second order statistics they need a higher order statistical analysis in contrast with monofractals which have a homogeneous scaling multifractals may include singularities of many types here we describe how a multiscale analysis can be used to describe the magnetic susceptibility data scaling properties for a deep well ktb germany down to about 9000 m a multiscale analysis describes the local and global singular behavior of measures or distributions in a statistical fashion the global analysis allows the estimation of the global repartition of the various holder exponents as such it leads to the definition of a spectrum d called the singularity spectrum the local analysis is related to the possibility of estimating the lipschitz regularity locally i e at each point of the support of a multifractal signal the application of both approaches to the ktb magnetic susceptibility data shows a meaningful correlation between the sequence of holder exponents vs depth and the lithological units the holder exponents reach the highest values for gneiss units intermediate ones for amphibolite units and the lowest values for variegated units faults are found to correspond to changes for h also when they are of intra lithological type

development of the topography controlled upper odra ice lobe scandinavian ice sheet in the fore mountain area of southern poland during the saalian glaciation abstract during the saalian drenthe glaciation the upper odra ice lobe constituted the most southern part of the scandinavian ice sheet in central europe the lobe was situated in an area with varied topography in the foreland of a mountain range the ice lobe had a complex form because it was subdivided into several smaller sublobes the primary factors that controlled the lobe were investigated it was found that the ice lobe development depended largely on the topography but the lithology of the ice sheet substratum was also highly important the topography controlled the main movement direction of the ice and caused a concentration of the ice flow in the axial part of the silesian lowland between subglacial morphological barriers which thereby formed a corridor of relatively fast flowing ice which was probably streaming and which supplied the lobe the topography also determined the ice flow within the lobe which strongly matched the valley system the presence of sediments with relatively low permeability at the base of the lobe the quaternary deposits are underlain by neogene clays caused high pore water pressure in the subglacial zone and triggered the basal movement of the ice sheet which promoted a rapid flow of the ice and favoured the development of the lobe the basal tills deposited from the active and passive ice and extant till patches without a fluvioglacial cover atop some parts of the studied area indicate spatially varying ice flow dynamics especially in the later stage of glaciation certain parts of the lobe underwent stagnation while in other parts the ice was probably still active the varied behaviour of the ice within the lobe was determined primarily by the topography and lithology of the substratum which produced spatially varied marginal compression and basal friction a model of the development of the lobe is proposed

mapping singularities with stream sediment geochemical data for prediction of undiscovered mineral deposits in gejiu yunnan province china abstract this paper proposes the concept of singularity for characterizing hydrothermal mineralization processes a singular physical process may result in anomalous amounts of energy release or material accumulation within a narrow spatial temporal interval mineralization can be considered as a type of singular process due to large amounts of material accumulation and element enrichment a spatial singularity mapping technique is developed based on the local singularity involved in the context of multifractal theory it assembles geochemical map at different scales and calculates an index indicating the scaling characteristics of enrichment and depletion of geochemical concentration at multiple scales this index was used for quantifying spatial singularity of mineralization associated geochemical anomalies a case study for the gejiu tin polymetallic mineral district yunnan province china demonstrates that the concepts of singularity and the singularity mapping technique are applicable and useful for delineating anomalies caused by mineralization and for predicting the locations of undiscovered mineral deposits

spatial distribution of ore deposits conventional spatial distributions such as the negative binomial and neyman scott have been proposed as models for the clustered distribution of ore deposits b b mandelbrot has proposed that ore deposits are clustered at many different scales and that fractal distributions are appropriate the apparent fractal characteristics of geologic controls on the locations of hydrothermal deposits self similar systems of fractures circulation cells and magmatic intrusions support his proposal examination of the spatial distribution of 4775 hydrothermal precious metal deposits in the basin and range western united states reveals fractal distributions acting within two scale ranges together covering the entire range from 1 to 1000 km this result gives additional credibility to concepts of regional controls on mineralization such as metallogenic provinces and tectonostratigraphic terranes the distribution of these ore deposits about a known occurrence follows a regular radial density law within a range of radii r of 1 to 15 km the probability density function of these deposits is given by d 0 46 r 1 17 and within a range of radii of 15 to 1000 km by d 0 08 r 0 83 where d is deposits per square kilometre

sedimentary record of a scandinavian ice sheet drainage system and till deposition over subglacial obstacles promoting basal sliding an example from southern poland abstract subglacial obstacles occurring in the path of advancing ice sheets generally generate higher longitudinal compression and higher frictional drag than a flat substrate however in the case of a soft sediment substratum they can have a very different effect on ice sheet behaviour this study concerns a substrate composed of very fine grained sediments with low permeability the relationship between subglacial obstacles and the overriding scandinavian ice sheet was studied in an area of southern poland where a small intervalley neogene clay ridge 40 m high was present based on sedimentological and structural analysis of subglacial till and gravelly sandy sediments the basal depositional processes and subglacial conditions and their influence on ice sheet behaviour were analysed the till and related deposits within the ridge reflecting high water pressure conditions and lack of glacitectonic deformations indicate that the clay ridge did not generate much resistance against the advancing ice sheet but instead favoured basal slip the impermeable substratum weakened the ice bed coupling and promoted ice detachment from the substratum gravelly sandy inclusions at the till clay contact indicate that during the first stage of ice sheet overriding a canal drainage system developed at the ice substrate interface varied geometry size and location of inclusions of sorted sediments suggest periodic instability of the canal system which could lead to its transformation from initially uniform to being composed of conduits of different sizes during later stages of ice sheet overriding a traction till was deposited and occasional drainage through a water film was sufficient to evacuate basal meltwater the resulting change in the character of subglacial drainage was probably related to variations in water pressure gradient during progressive ice sheet advance

the late weichselian glacial record in northern poland a new look at debris transport routes by the fennoscandian ice sheet abstract the area of the kashubian coastland and areas adjacent to the northern part of the lower vistula valley northern poland were involved in the major transgressive phases distinguished in poland during the late weichselian due to the small scale of the regressions between the different phases of the late weichselian the ice sheet usually deposited only one till but with a complex vertical profile based on the studies of the directional properties petrographic composition of the fine gravel fraction and the analysis of indicator erratics the dichotomy of the till bed was demonstrated the petrographic composition of the gravel fraction in tills together with the analysis of the indicator erratics and delimitation of the theoretical boulder centres were used to determine the direction of the influx of ice masses this allowed speculation on the reasons for the different dynamics of the fennoscandian ice sheet fis as well as the operation and time variability of the baltic ice stream bis it was emphasised that the delivery system of debris by the ice sheet might have been complex and multidirectional more than one route it has been suggested that changes in the petrographic composition of the gravel fraction of the glacial sediments did not have to be associated only with shifting the centre of glaciation but may have resulted from a change in the thermal regime of the ice sheet s bed in the source area especially with the spread of the cold regime zone and depended on the dynamics of the ice sheet stream or sheet flow as well as the spatial and temporal conditions of its development in the deposition area

effects of principal stress directions on 3d failure conditions in cross anisotropic sand abstractan experimental program was carried out to study the variation of shear strength of cross anisotropic deposits of fine nevada sand under three dimensional 3d conditions using a recently developed torsion shear apparatus a total of 44 drained torsion shear tests were performed at a constant mean confining stress m constant intermediate principal stress ratios as indicated by b 2 3 1 3 and principal stress directions the experiments were performed on large hollow cylinder specimens deposited by dry pluviation and tested in an automated torsion shear apparatus the specimens had a height of 40 cm an average diameter of 20 cm and a wall thickness of 2 cm the 3d failure surface of fine nevada sand is presented with discrete combinations of and intermediate principal stress the effects of these two variables on the shape of the failure surface are presented the friction angles are highest for 0 for all b values and show a dip in strength with the lowest values near 67 5

an outline of the pleistocene stratigraphy of the kleszczow graben bechatow outcrop central poland abstract the pleistocene sequence of the kleszczow graben central poland is located in a brown coal quarry 8 km long and 4 km wide it contains ten separate organic horizons in part stacked one above another and in part correlated by reference to associated inorganic units using heavy minerals and gravel petrography three of the organic horizons represent interglacials ferdynandovian mazovian holsteinian and eemian others represent interstadial or periglacial deposits the tertiary quaternary boundary is recorded at the site by reuverian c and prae tiglian biostratigraphy occurring in a single section a major hiatus exists above the prae tiglian and lower pleistocene and cromerian deposits are absent glacial deposits are represented by three elsterian tills five saalian tills and glaciofluvial and glaciolacustrine deposits the czyzow formation lies between the elsterian and saalian deposits and contains at least two interglacials the ferdynandovian and mazovian and several interstadial units without glacial intervening deposits the lower saalian odranian drenthe deposits are separated from the middle saalian wartanian 1 by fluvial sands and organic deposits of the pilica interstadial the middle wartanian 1 and upper saalian wartanian 2 also may be separated by an interstadial palaeosol the evidence from the kleszczow graben supported by other central european quaternary sequences suggest that only four glaciations occurred within the region during the middle pleistocene and that these glaciations were separated by long periods with a complex climate ranging from temperate to periglacial

steppe mammoth mammuthus trogontherii remains in their geological and cultural context from belchatow poland a consideration of human exploitation in the middle pleistocene abstract in 1981 and 1991 mammoth remains and associated fauna were found in central poland at the belchatow opencast mine in sandy gravel deposits most of them lay at approximately 160 175 m above mean sea level a s l located in the lower and upper members of the alluvial chojny formation this formation belongs to the middle pleistocene and can be connected with the mazovian mis 11 holsteinian or zbojnian mis 9 reinsdorf interglacial the belchatow mammoth assemblage described here consists of cranial and postcranial elements analysis of their morphological characteristics and osteometrics are used to demonstrate that at least two molars and one tusk belong to mammuthus trogontherii and that the tusk belonged to a male on the basis of the minimum number of elements of the most common element left incisors the mammoth remains represent at least two individuals based upon the different ages of death for the various elements it appears that they represent several individuals the bulk of the mammoth remains were recovered from the oldest depositional cycle in the lower member of chojny formation and are therefore coincident with a shrub tundra environment and cool temperate conditions they were deposited in sediments formed by a meandering river with a fairly low power of flow and were buried soon after transport over a short distance this conclusion is also supported by the palaeobotanical data an additional element a costa was recovered from the upper member of the chojny formation which is associated with the cooling conditions the enveloping deposit appears to be the result of a series of more rapid discharge events by a braided river this element is distinguished from those elements recovered from the lower member due to the presence of a series of unusual striations sem analysis suggests that some of the striations were probably made by chipped stone tools used in a slicing action as if the result of the filleting of flesh from the rib area the time frame for the depositional context of the costa suggests that the striations may have been made by one of several possible human taxa that occurred in central europe during this period including homo heidelbergensis given the dearth of human skeletal remains from this region and time period this represents the earliest and only example of middle pleistocene human butchering activity in poland the remains discussed in this paper are presented in light of their depositional and cultural contexts which not only increases our knowledge of the occurrence of m trogontherii in poland but also provides increased evidence for lower palaeolithic human activity in central europe during an early interglacial

landform and sediment imprints of fast glacier flow in the southwest laurentide ice sheet evidence for former fast glacier flow ice streaming in the southwest laurentide ice sheet is identified on the basis of regional glacial geomorphology and sedimentology highlighting the depositional processes associated with the margin of a terrestrial terminating ice stream preliminary mapping from a digital elevation model of alberta identifies corridors of smoothed topography and corridor parallel streamlined landforms megaflutes to mega lineations that display high levels of spatial coherency ridges that lie transverse to the dominant streamlining patterns are interpreted as a series of minor recessional push moraines b thrust block moraines or composite ridges hill hole pairs constructed during readvances surges and c overridden moraines cupola hills apparently of thrust origin together these landforms demarcate the beds and margins of former fast ice flow trunks or ice streams that terminated as lobate forms localised cross cutting and or misalignment of flow sets indicates temporal separation and the overprinting of ice streams lobes the fast flow tracks are separated by areas of interlobate or inter stream terrain in which moraines have been constructed at the margins of neighbouring competing ice streams outlet glaciers this inter stream terrain was covered by more sluggish non streaming ice during full glacial conditions thin tills at the centres of the fast flow corridors in many places unconformably overlying stratified sediments suggest that widespread till deformation may have been subordinate to basal sliding in driving fast ice flow but the general thickening of tills towards the lobate terminal margins of ice streams outlet glaciers is consistent with subglacial deformation theory in this area of relatively low relief we speculate that fast glacier flow or streaming was highly dynamic and transitory sometimes with fast flowing trunks topographically fixed in their onset zones and with the terminus migrating laterally the occurrence of minor push moraines and flutings and associated landforms because of their similarity to modern active temperate glacial landsystems are interpreted as indicative of ice lobe marginal oscillations possibly in response to seasonal climatic forcing in locations where meltwater was more effectively drained from the glacier bed further north the occurrence of surging glacier landsystems suggests that persistent fast glacier flow gave way to more transitory surging possibly in response to the decreasing size of ice reservoir areas in dispersal centres and also locally facilitated by ice bed decoupling and drawdown initiated by the development of ice dammed lakes copyright 2008 john wiley sons ltd

identifying gravity anomalies caused by granitic intrusions in nanling mineral district china a multifractal perspective several power law relationships of geophysical potential fields have been discussed recently with renewed interests including field value distance f r and power spectrum wavenumber p models the singularity mapping technique based on the density concentration area c a power law model is applied to act as a highpass filter for extracting gravity and magnetic anomalies regardless of the background value and to detect the edges of gravity or magnetic sources with the advantage of scale invariance this is demonstrated on a synthetic example and a case study from the nanling mineral district southern china compared with the analytic signal amplitude and total horizontal gradient methods the singularity mapping technique provides more distinct and less noisy boundaries of granites than traditional methods additionally it is efficient for enhancing and outlining weak anomalies caused by concealed granitic intrusions indicating that the singularity method based on multifractal analysis is a potential tool to process gravity and magnetic data

depth estimation from the scaling power spectral density of nonstationary gravity profile a technique to estimate the depth to anomalous sources from the scaling power spectra of long nonstationary gravity profiles is presented the nonstationary profile is divided into piecewise stationary segments based on the criterion of optimum gate length in which the time varying and time invariant autocorrelation functions are similar the division of a nonstationary into piecewise stationary allows identification of the portion of the crust with different geological histories and using the stationary portion of the gravity profiles more consistent depths to the anomalous sources have been obtained the technique is tested with the synthetic gravity profile and applied along the jaipur raipur geotransect in western and central india the geotransect has been divided into four stationary parts vindhyan low bundelkhand low narmada rift and chhattisgarh basin each section corresponding to a different geological formation forward modeling of gravity data using results of each stationary section is carried out to propose the subsurface structure along the jaipur raipur transect

dynamics of the north american ice sheet complex during its inception and build up to the last glacial maximum the north american ice sheet complex played a major role in global sea level fluctuations during the late quaternary but our knowledge of its dynamics is based mostly on its demise from the last glacial maximum lgm a period characterised by non linear behaviour in the form of punctuated ice margin recession episodic ice streaming and major shifts in the location of ice divides in comparison knowledge of the pre lgm ice complex is poorly constrained largely because of the fragmentary nature of the evidence relating to ice sheet build up in this paper we explore the inception and growth of ice 120 20 ka using a glacial systems model which has been calibrated against a large and diverse set of data relating to the deglacial interval we make use of calibration data prior to the lgm but its scarcity introduces greater uncertainty which is partly alleviated by our large ensemble analysis results suggest that following the last interglaciation oxygen isotope stage ois 5e the ice complex initiated over the north eastern canadian arctic and in the cordillera within a few thousand years it then underwent rapid growth to an ois 5 maximum at 110 ka 5d and covered 70 of the area occupied by the lgm ice cover although only 30 by volume an ois 5 minimum is modelled at 80 ka 5a before a second phase of rapid growth at the start of ois 4 which culminated in a large ice complex at 65 ka almost as large as at the lgm subsequent deglaciation was rapid maximum modelled sea level contribution of 16 cm per century and resulted in an ois 3 minimum between ca 55 60 ka thereafter the ice complex grew towards its lgm configuration interrupted by several phases of successively less significant mass loss our results support and extend previous inferences based on geological evidence and reinforce the notion of a highly dynamic pre lgm ice complex e g with episodes of 10 s m of eustatic sea level equivalent in 50 but even the thin ois 5 ice sheets exhibit fast flow features several 1000 m a 1 in major topographic troughs notwithstanding the severe limitations imposed by the use of the shallow ice approximation we note that most fast flow features generated prior to the lgm correspond to the location of known ice streams during deglaciation i e in major topographic troughs and over soft sediments at the southern and western margins moreover the modelled flux of these ice streams sensu lato appears to be non linearly scaled to ice sheet volume i e there is no evidence that decay phases were associated with significantly increased ice stream activity this hypothesis requires testing using a model with higher order physics and future modelling would also benefit from additional pre lgm constraints e g dated ice free margin positions to help reduce and quantify uncertainties

the geology of the southeastern baltic sea a review the baltic sea particularly its southeastern part is discussed in the paper investigations of regional character as well as specialized studies in the area are reviewed general historical works

palaeoglaciology of an ice sheet through a glacial cycle the european ice sheet through the weichselian abstract satellite images provide unique means of identifying large scale flow generated lineations produced by former ice sheets they can be interpreted to reconstruct the major elements which make up the integrated large scale structure of ice sheets ice divides ice streams interstream ridges ice shelves calving bays the evolving palaeoglaciological structure of the european ice sheet during its decay from the last glacial maximum lgm is reconstructed by reference to these components and in the context of a new map showing isochrons of retreat during the retreat phase in particular the time dependent dynamic evolution of the ice sheet and the pattern of ice stream development are reconstructed crossing lineations are widespread the older ones are suggested to have formed during molten bed phases of ice sheet growth and preserved by frozen bed conditions during the glacial maximum particularly in areas which lay during deglaciation beneath ice divides and inter ice stream ridges both areas of slow flow and possibly frozen bed conditions four phases of growth a1 to a4 and five phases of decay r1 to r5 are used to describe the major climatically and dynamically determined stages in the evolution of the ice sheet through the last glacial cycle the growth and decay patterns are quite different and associated with major shifts in the ice divide reflecting growth from the fennoscandian mountains and decay away from marine influenced margins these patterns were determined by the locations of nucleation areas spatial patterns of climate and calving at marine margins the prevalence of streaming within the retreating ice sheet suggests that the mean elevation of the ice sheet was lower than predicted from glaciological models which do not include streaming and that this might reconcile glaciological models and earth rheology models which infer paleao ice sheet thickness by inverting sea level data

climatostratigraphy of interglacials in poland middle and upper pleistocene lower boundaries from a polish perspective abstract the brunhes matuyama paleomagnetic boundary has been identified in some key interglacial sites in poland helping in interpret the results of many years climatostratigraphic research the major qualitative stratigraphic boundary is located at the onset of the mazovian interglacial holsteinian that separates the older composite from the younger simple interglacials the two composite interglacials comprise 2 3 interglacial rank warmings each separated by profound but non glacial coolings the four simple interglacials mazovian interglacial included are expressed by single warmings only each interglacial possesses a characteristic pollen succession and the successive interglacials are interbedded with tills of the scandinavian provenance simple interglacials are typical of mis 11 1 and reflect a climate system predominated by 100 ka orbital cycles composite interglacials are characteristic of the interval mis 22 12 and reflect a transition from a climate system predominated by 41 ka orbital cycles to 100 ka cycles i e the mid pleistocene revolution based on these general differences the mis 23 22 and mis 12 11 boundaries are recommended as key thresholds during the pleistocene and could be reconsidered as the lower boundaries of middle and upper pleistocene respectively

fractals in petrology abstract a fractal power law distribution is the only statistical distribution applicable to a scale invariant process one of the major problems in petrology is the distribution of trace elements in the earth s crust extreme values of this distribution result in ore deposits there is accumulating observational evidence that tonnage grade statistics of ore deposits are often fractal power law rayleigh distillation and chromatographic models can explain power law fractal distributions for the extreme values of trace element concentrations an alternative fractal approach to problems in petrology is to use self affine fractals the standard approach is to take a fourier transform of a continuous signal an example would be the concentration of a mineral along a linear track if the fourier coefficients scale as a power law of the wavelength the distribution is a self affine fractal many well logs give this result multifractal analyses can also be applied to problems in petrology

terrestrial ice streams a view from the lobe abstract the glacial landforms of minnesota are interpreted as the products of the lobate extensions of ice streams that issued from various ice sheds within the laurentide ice sheet low relief till plains trough shaped lowlands boulder pavements and streamlined forms make up the subglacial landsystem in minnesota that is interpreted as having been formed by streaming ice extremely uniform tills are created subglacially in a way that remains somewhat mysterious at the ice margins thrust moraines and hummocky stagnation topography are more common than single crested simple moraines if the ice lobes had repeated advances subglacial drainage features are obscure up ice but are present down ice in the form of tunnel valleys eskers spooner hills and associated ice marginal fans ice streaming may occur when basal shear stress is lowered as a result of high subglacial water pressure subglacial conditions that allow the retention of water will allow an ice lobe to extend far beyond the ice sheet as long as the ice shed also supports the advance by supplying adequate ice even with adequate ice flux however the advance of an ice lobe may be terminated at least temporarily if the subglacial water is drained through tunnel valleys or perhaps a permeable substrate thrust moraines and ice stagnation topography will result from sudden drainage although climate change is ultimately responsible for the accumulation of ice in the laurentide ice sheet the asynchronous advances and retreats of the ice lobes in the mid continent are strongly overprinted by the internal dynamics of individual ice streams as well as the interaction of ice sheds which obscure the climate signal

approximating edges of source bodies from magnetic or gravity anomalies cordell and grauch 1982 1985 discussed a technique to estimate the location of abrupt lateral changes in magnetization or mass density of upper crustal rocks the final step of their procedure is to identify maxima on a contoured map of horizontal gradient magnitudes we attempt to automate their final step our method begins with gridded magnetic or gravity anomaly data and produces a plan view of inferred boundaries of magnetic or gravity sources the method applies to both local surveys and to continent wide compilations of magnetic and gravity data e g zietz 1982 simpson et al 1983a kane et al 1982

anisotropic three dimensional behavior of a normally consolidated clay an experimental study is presented of the influence of the intermediate principal stress on the stress strain pore pressure and strength characteristics of a normally consolidated natural anisotropic clay san francisco bay mud under undrained conditions consolidated undrained triaxial compression tests and triaxial tests with independent control of all three principal stresses on cubical specimens were performed the stress strain behavior and the pore pressure characteristics as well as the effective stress failure surface can be described as being cross anisotropic key words anisotropic soils clays deformation shear strength triaxial tests

fennoscandian palaeoglaciology reconstructed using a glacial geological inversion model the evolution of ice sheet configuration and flow pattern in fennoscandia through the last glacial cycle was reconstructed using a glacial geological inversion model i e a theoretical model that formalises the procedure of using the landform record to reconstruct ice sheets the model uses mapped flow traces and deglacial melt water landforms as well as relative chronologies derived from cross cutting striae and till lineations as input data flow trace systems were classified into four types i time transgressive wet bed deglacial fans ii time transgressive frozen bed deglacial fans iii surge fans and iv synchronous non deglacial event fans using relative chronologies and aggregation of fans into glaciologically plausible patterns a series of ice sheet configurations at different time slices was erected a chronology was constructed through correlation with dated stratigraphical records and proxy data reflecting global ice volume geological evidence exists for several discrete ice sheet configurations centred over the scandinavian mountain range during the early weichselian the build up of the main weichselian fennoscandian ice sheet started at approximately 70 ka and our results indicate that it was characterised by an ice sheet with a centre of mass located over southern norway this configuration had a flow pattern which is poorly reproduced by current numerical models of the fennoscandian ice sheet at the last glacial maximum the main ice divide was located overthe gulf of bothnia a major bend in the ice divide was caused by outflow of ice to the northwest over the lowest part of the scandinavian mountain chain widespread areas of preserved pre late weichselian landscapes indicate that the ice sheet had a frozen bed core area which was only partly diminished in size by inward transgressive wet bed zones during the decay phase

successive subglacial depositional processes as interpreted from basal tills in the lower vistula valley n poland abstract three basal till facies from the lower vistula valley were examined the lowest facies a sandy diamicton with characteristic sand inclusions forming detached and attenuated folds is overlain by a bedded till characterized by alternating diamictons and sorted sediment layers the uppermost till facies is a homogeneous diamicton the three till facies must have been formed by complex subglacial sedimentary processes during the first late weichselian ice advance the lowest till facies is interpreted as a deformation till and accumulated during the initial stage of the ice advance the middle facies represents a stagnation phase during the initial ice advance and was deposited during recurrent periods of subglacial melt out followed by meltwater sedimentation the upper till facies was deposited by direct subglacial melt out during a stage of stagnant ice it is suggested that bed deformation and temporarily enhanced basal sliding have been caused by ice streaming at the time of the ice sheet advance and just before its stagnation

radiocarbon calibration curve spanning 0 to 50 000 years bp based on paired 230 th 234 u 238 u and 14 c dates on pristine corals abstract radiocarbon dating is the most widely used dating technique in the world recent advances in accelerator mass spectrometry ams and sample preparation techniques have reduced the sample size requirements by a factor of 1000 and decreased the measurement time from weeks to minutes today it is estimated that more than 90 percent of all measurements made on accelerator mass spectrometers are for radiocarbon age dates the production of 14 c in the atmosphere varies through time due to changes in the earth s geomagnetic field intensity and in its concentration which is regulated by the carbon cycle as a result of these two variables a radiocarbon age is not equivalent to a calendar age four decades of joint research by the dendrochronology and radiocarbon communities have produced a radiocarbon calibration data set of remarkable precision and accuracy extending from the present to approximately 12 000 calendar years before present this paper presents high precision paired 230 th 234 u 238 u and 14 c age determinations on pristine coral samples that enable us to extend the radiocarbon calibration curve from 12 000 to 50 000 years before present we developed a statistical model to properly estimate sample age conversion from radiocarbon years to calendar years taking full account of combined errors in input ages and calibration uncertainties our radiocarbon calibration program is publicly accessible at http www radiocarbon ldeo columbia edu along with full documentation of the samples data and our statistical calibration model

record of the vistula ice lobe advances in the late weichselian glacial sequence in north central poland during the last glacial maximum lgm the vistula ice lobe was one of the key morphological elements at the southern margin of the scandinavian ice sheet in north central poland the area of the vistula ice lobe experienced two ice sheet advances of varied extent the older one is correlated with the leszno brandenburg phase and the younger one is correlated with the poznan frankfurt phase sedimentological research and luminescence dating of the late weichselian glacial sequence in the vistula ice lobe area was conducted a new scenario of the late weichselian ice events in the area is presented the limit of the leszno phase within the vistula ice lobe was much smaller than had been accepted previously and its age is estimated to be about 20 300 bp significant ice sheet retreat was

large scale reorganization and sedimentation of terrestrial ice streams during late wisconsinan laurentide ice sheet deglaciation glacial geomorphological mapping of shuttle radar topography mission srtm data from the western canadian prairies demonstrates that during the last late wisconsinan deglaciation of the laurentide ice sheet terrestrial ice streams underwent a major reorganization of their flow configuration this reorganization involved a 90 shift in flow direction and was accompanied by a corresponding increase in the influence of topography on streaming flow ice streams included both topographically confined and pure ice streams that flowed independent of topography streaming flow is recorded by suites of highly elongate 60 km long subglacial bedforms bounded sharply at their lateral margins by prominent moraines initial streaming flow was unconfined by topography but was replaced progressively and crosscut by younger topographically confined flows flow reorganization is inferred to have been caused by temporal and spatial variations in the interaction between frozen and thawed bed conditions with thinning and shutdown of one ice stream ultimately triggering initiation of others this highlights the role of internal glaciodynamically driven reorganization in triggering streaming flow within large ice sheets and shows that large scale flow reorganization can occur over the time scale of a single deglaciation in terrestrial ice streams

laurentide glacial landscapes the role of ice streams glacial landforms of the north american prairie can be divided into two suites that result from different styles of ice flow 1 a lowland suite of level to streamlined till consistent with formation beneath ice streams and 2 an upland and lobe margin suite of thick hummocky till and glacial thrust blocks consistent with formation at ice stream and ice lobe margins southern laurentide ice lobes hypothetically functioned as outlets of ice streams broad branching lowlands bounded by escarpments mark the stable positions of the ice streams that fed the lobes if the lobes and ice streams were similar to modern ice streams their fast flow was facilitated by high subglacial water pressure favorable geology and topography in the midcontinent encouraged nonuniform ice flow and controlled the location of ice streams and outlet lobes

genesis of transverse kame trains in eastern poland abstract transverse kames forming trains perpendicular to the direction of ice sheet advance are rare morphological elements in previously glaciated areas the genesis of an example from the ice contact zone of the wartanian glaciation in eastern poland is discussed the transverse kames there form two main distinctly separated sub parallel trains their sedimentary successions fill erosional troughs incised in the pre wartanian deposits on northern slopes they consist of thick glaciofluvial sand and glaciofluvial glaciolacustrine sandy silty units that are covered with a thin usually discontinuous glacial till succession the genesis of this kame type has been modelled it is concluded that transverse kames developed in two phases 1 erosion of the substratum in subglacial channels during initial deglaciation and 2 glaciofluvial deposition in crevasses during advanced deglaciation in the form of low energy fans periodically submerged under stagnant water followed locally by a cover of flowtills both the ablation of the ice and the accumulation of the kame deposits were controlled by the co occurrence of ice zones either enriched or impoverished with sediment zonal enrichment of ice with debris was determined by the development of shear zones over substratum elevations that were inclined up ice the formation and subsequent infilling of crevasses both took place in zones of relatively clean ice so that the resulting kames form a train perpendicular to the direction of ice movement