quaternary tectonics of the outer west carpathians poland abstract quaternary tectonic activity in the polish segment of the outer west carpathians has been relatively weak and can be reconstructed on the basis of indirect evidence provided by geomorphological mapping the construction of various morphometric maps based on mathematical transformation of the present day topography and the use of some mathematical techniques to model the theoretical longitudinal river profiles and the valley network and to process statistically the drainage pattern parameters morphological evidences of tectonic movements include deformed strath terraces differentiated amounts and rates of fluvial incision in individual geomorphic units which occurred despite of regionally consistent quaternary climatic conditions throughout the west carpathians and more or less uniform bedrock resistance to erosion as well as changes in the drainage network the values of some morphometric indices like abnormally high river bed gradients and bifurcation ratios or low valley floor width valley height ratios differ throughout that part of the carpathian arc and cluster into a number of zones that are aligned subparallel to the mountain belt and coincide with geomorphic units showing upwarped strath terraces these zones become more numerous from the west to the east and some of them are located at or in front of the present day carpathian frontal thrust cutting it obliquely and passing into the eastern carpathian foredeep the spatial arrangement of such zones showing alternatively uplifting subsiding tendencies suggests that one of the main driving forces leading to quaternary tectonic deformations is that resulting from the relaxation of remnant horizontal stresses built up during the late neogene thrusting

mapping surface mineralogy using imaging spectrometry abstract imaging spectrometry simultaneous measurement of spectra and images in up to hundreds of spectral channels or bands is a proven technology for identifying and mapping minerals based on their reflectance or emissivity signatures also known as hyperspectral imaging or hsi extraction of key spectral signatures from these data allows direct identification of iron minerals such as hematite goethite and jarosite in the visible near infrared vnir clays carbonates micas sulfates and other minerals in the short wave infrared swir and silicates and carbonates in the long wave infrared lwir the unique capability of imaging spectrometry to produce detailed maps of the spatial distribution of specific minerals mineral assemblages and mineral variability on the surface of earth makes it an ideal tool for enhanced geomorphic mapping case histories illustrate the use of hsi for characterizing and mapping active and relict geothermal hydrothermal systems and determining relations between mineralogy and derived landforms imaging spectrometry used in conjunction with complimentary datasets such as insar interferometric synthetic aperture radar light detection and ranging lidar or stereo photogrammetric derived digital elevation models dems provides a unique means of visualizing the spatial distribution and association of mineralogy with topography thus contributing to the understanding of the relations between geology and landscape and to improved interpretation of surface geologic processes

diagenetic cycling of arsenic in amazon shelf sediments in order to help elucidate major natural controls on the diagenetic behavior of as vertical profiles of total dissolved and solid phase as were measured in amazon shelf deposits a deltaic region little influenced by human activity arsenic distributions are typically characterized by subsurface porewater maxima and surficial solid phase enrichment maximum porewater as concentrations 2 4 m are an order of magnitude greater than levels reported in most other coastal marine environments and elevated concentrations extend several meters below the sediment surface dissolved as varies inversely with easily leachable as 40 140 nmol g 1 in the solid phase and directly with increases in solid phase fe ii these patterns reflect a strong redox coupling with fe whereby oxidized as is associated with fe oxyhydroxides in surface sediments then subsequently reduced and released upon burial in the extensive suboxic zone upward diffusion and intense physical reworking of sediments presumably releases the dissolved arsenic fraction to the water column or allows for re adsorption in surface sediments arsenic porewater concentrations generally increase away from the river in some cases regular seasonal variations are evident apparently corresponding to nonsteady state ingrowth of diagenetic profiles following extensive sediment reworking during rising river flow the massive cycling of as in amazon shelf sediments is likely due to the combined effects of intense chemical weathering in regions of the drainage basin production of oxides and a turbulent physical regime present on the shelf both of which promote sedimentary cycling of fe and coupled elements during early diagenesis

active tectonics and drainage evolution in the tunisian atlas driven by interaction between crustal shortening and mantle dynamics abstract active tectonics in north africa are fundamentally driven by nw se directed slow convergence between the nubia and eurasia plates leading to a region of thrust and strike slip faulting in this paper we analyse the morphometric characteristics of the northern tunisia sector we aim to identify unknown active tectonic structures and to further understand the mechanisms driving the drainage evolution in this region the interpretation of morphometric data was ground truthed with field data our analysis indicates that recent fluvial captures have been the main factor driving fluvial network reorganization in ne tunisia the medjerda river has increased its drainage area during the quaternary by capturing adjacent axial valleys to the north and south of its drainage divide these captures are probably driven by the gradual uplift of adjacent axial valleys by reverse oblique faults or associated folds like el alia teboursouk and dkhila faults our fieldwork found that these faults cut holocene sediments thus showing recent fault activity the growth and stabilization of the axial medjerda river contrary to the natural transverse drainage development of mature orogens might be caused by a combination of crustal shortening structures and mantle dynamic processes the medjerda river flows sw ne from the south atlassic dextral transfer zone to the regional topographic low defined by the gulf of gabes and the straits of sicily which in turn may be influenced by the underlying tunisian slab in the region

late quaternary sedimentary environments and landforms in the ganges delta abstract late quaternary sediments deposited since the lowest stand of sea level during the last glacial maximum in the ganges delta and its surrounding region were classified into five units according to their sedimentary facies these are the lowest unit of sandy gravels the lower unit of sand with a few gravels and the middle upper and uppermost units consisting mainly of sand and silt with occasional peat layers the contact between the lower and middle units is fairly sharp and the upper part of the lower unit is oxidized in some places this suggests a period of subaerial exposure after the deposition of the lower unit during the low stand of sea level about the time of the last glacial maximum rivers in the ganges delta and its surrounding region dissected the surfaces of the region and deposited the lowest unit on the valley floors the lower unit was deposited over the lowest unit during an early stage of the post glacial transgression between ca 12 000 yr bp and 10 000 yr bp the surface of the delta was slightly dissected and the top of the lower unit was weathered and oxidized following this period the middle and upper units of alluvial or deltaic sand and silt with occasional peat were deposited the coastline in the early holocene retreated towards the central part of the present ganges delta in the middle and late holocene the silt and clay with occasional peat layers of the uppermost unit indicate that the lowland gradually became marshy and poorly drained as the rate of transgression became slower

morphological and morphometric approach to the study of the structural arrangement of northeastern abruzzo central italy abstract the morphotectonic research at the dipartimento di scienze della terra of the universita di roma la sapienza aims to define the role of tectonics and neotectonics in the morphological evolution of central italy in this context the relationships between morphology and tectonics have been investigated in an area of northern abruzzo extending from the apennine chain to the adriatic sea morphological and morphometric analyses carried out show that the geomorphological evolution of the study area was strongly affected by tectonics especially recently the most recent extensional tectonics intersect the previous compressive structures overthrust reverse faults folds strike slip faults determining the structural arrangement characterized by uplifted and downthrown blocks morphological analysis shows that extentional tectonics occurred with the following alignments nw se nnw sse ne sw ene wsw n s and e w the spatial variability of amplitude of relief values corroborated the observations obtained from previous analyses in particular the existence of different blocks differentially uplifted along the alignments mentioned above finally data obtained through the statistical analysis of preferred stream orientations confirm the previous considerations showing that the same tectonic directions markedly influenced the drainage network development streams of lower order preferentially follow the n s and e w directions which suggests that these tectonic trends were active until very recent times at least up to the late pleistocene the results obtained testify both to the effectiveness of the methodological approach and the likelihood of the proposed morphotectonic arrangement of the study area

arsenic enrichment in groundwater of west bengal india geochemical evidence for mobilization of as under reducing conditions abstract the mechanism of as release and source s of as has been investigated in a small part of a watershed in the murshidabad district of west bengal analyses include major ion and trace element concentrations as well as o h and s isotope ratios of groundwater surface water and a thermal spring the results indicate that all water samples belong to the ca hco 3 type except for the thermal spring which is of the na hco 3 type shallow and deeper groundwaters have distinct hydrochemical features high as contents were registered only in the deeper groundwater horizon factor analysis and the distribution pattern of major and trace elements indicate that as is present in the aquifer as a scavenged phase by fe iii and to a lesser extent by mn iv phases the release of as into the groundwater occurs gradually in successive stages corresponding to the actual redox state in the aquifer the main stage of as release is related to the bacterial reduction of fe iii to fe ii i e to the simultaneous dissolution of fe oxyhydroxides low redox conditions in highly polluted areas are indicated by low so 4 concentration and high 34 s values during bacterial so 4 reduction residual so 4 in groundwater is depleted in the lighter s isotope 32 s however the cause of the gradual decrease of the redox state in the groundwater is still not well understood

formation processes of framboidal pyrite abstract pyrite framboid formation may be the result of four consecutive processes 1 nucleation and growth of initial iron monosulfide microcrystals 2 reaction of the microcrystals to greigite fe 3 s 4 3 aggregation of uniformly sized greigite microcrystals i e framboid growth and 4 replacement of greigite framboids by pyrite the uniform morphology uniform size range and ordering of the microcrystals in individual framboids as well as the range of observed framboid structures from irregular aggregates to densely packed spherical aggregates and polyframboids are consequences of these processes using dlvo theory derjaguin landau verwey and overbeek we have evaluated the stability of colloidal iron monosulfide suspensions with ionic strengths typical of marine and lacustrine waters in addition to van der waals attractive and double layer repulsive forces a term is included to account for the ferrimagnetic properties of greigite numerical models predict that magnetically saturated greigite particles 0 1 m in diameter will rapidly aggregate in either marine or fresh water the aggregation model is in agreement with the sequence of greigite formation followed by pyrite framboid formation established in a previous experimental study sweeney and kaplan 1973 and is consistent with the occurrence of framboids composed of other magnetic minerals e g greigite magnetite and magnesioferrite based on the temperature dependent magnetic properties of greigite and aging experiments in hydrothermal solutions this mechanism for framboid formation via precursor greigite could operate to temperatures of 200 c consistent with the occasional occurrence of pyrite framboids in the paragenesis of metalliferous ore deposits

redox control of arsenic mobilization in bangladesh groundwater abstract detailed hydrochemical measurements 34sso4 and 3h analyses were performed on 37 groundwater samples collected during february 1999 january and march 2000 from 6 locations in eastern and southeastern bangladesh to examine redox processes that lead to as mobilization in groundwater the study sites were chosen based on available nation wide as surveys to span the entire spectrum of as concentrations in bangladesh groundwater and to represent 3 of 5 major geological units of the ganges brahmaputra delta uplifted pleistocene terrace fluvial flood plain and delta plain arsenic was found to be mobilized under fe reducing conditions in shallow aquifers 50 g l or 0 7 m were always accompanied by high dissolved hco3 4 mm and were close to saturation with respect to calcite groundwater enriched in as 200 800 g l or 2 7 10 7 m and phosphate 30 100 m but relatively low in dissolved fe 5 40 m probably resulted from re oxidation of reducing as and fe enriched water this history was deduced from isotopic signatures of 34sso4 and 3h2o 3h to delineate the nature of redox changes for some of the reducing groundwaters in contrast as is not mobilized in presumed pleistocene aquifers both shallow 30 60 m and deep 150 270 m because conditions were not reducing enough due to lack of sufficient o2 demand

aeolian erosional lineations in the libyan desert dakhla region egypt abstract this paper presents results of a study of aeolian erosion at the landscape scale there have been few such studies in desert geomorphology compared to those focused on individual landforms and on rock surface sculpture the present study area lies in the southern part of the libyan desert in south central egypt between 25 and 27 n 29 and 30 e bedrock comprises paleogene limestone of various lithologies climate is hyperarid the following topics are treated i correspondences between rock outcrop belts and belts of terrain lineated by aeolian erosion and unlineated terrain ii the effect of lithology on aeolian lineation which works through the presence or absence of chert in the limestones lineation is produced by aeolian erosion in chert free poor rocks whereas erosion of chert rich rocks produces a desert pavement that armors the surface suppressing erosion iii the effect of large valleys eroded upwind of lineated terrain which deflect winds and trap sand ending erosion so that downwind lineations are reduced and finally erased by weathering iv sample lineated landscapes in the area show stages of evolution arranged in the time domain into a proposed cycle of aeolian erosion the cycle progresses from initial smooth plain to grooves separating long blade shaped ridges to segmentation of ridges into shorter blades along diagonal joints to streamlining of shorter blades and size reduction to final planation in any one wind parallel swath of lineated terrain stages in the cycle progress downwind in the space domain so that upwind landscapes are more advanced in the cycle v the structure of air flow responsible for lineation is still uncertain but initial grooving may respond to stable longitudinal horseshoe vortices or self organized regularity of erosion by random vortices subsequently the erosion pattern is fixed by evolving relief vi large smooth basins within the lineated terrain were carved by aeolian erosion before oxygen isotope stage ois 5 70 130 ka as were similar basins along the dakhla piedmont below the scarp little geomorphic change has occurred since so in this field of aeolian erosional lineations aels the aeolian erosion cycle may have occupied 10 times as long since continental scale aridity set in at ca 2 4 ma there have been only two cycles in this area a completed cycle earlier than the current incomplete one is indicated by rare small yardangs riding piggyback on larger ones

late quaternary uplift and valley evolution in the northern apennines lamone catchment abstract the topographic evolution of mountain chains is fundamentally dictated by the balance of erosional and tectonic processes in the northern apennines several questions about the late holocene to present deformation style and uplift rates are still open we consider a typical ne facing drainage basin focusing on all the geomorphic markers capable of supplying direct or indirect information regarding tectonic forcing on the landscape characteristics of altitude and relief drainage pattern river profile and fluvial response expressions were found to be in good agreement indicating that the most recent tectonic activity consists of a general persistent uplift of the chain associated with an extensional regime where different sectors are distinguished through differential uplift such differences have been found to act both along and transverse to the chain causing similar coherent patterns of response in erosional processes the geomorphology of the catchment displays several features which together with the long sustained tectonic forcing indicate the near attainment of a dynamic equilibrium between the rates of tectonic forcing and erosional processes creating steady state topography

automated recognition of valley lines and drainage networks from grid digital elevation models a review and a new method abstract the literature on valley and drainage line recognition from grid digital elevation models dems is reviewed two problems preventing the successful delineation of fully connected drainage networks of single line width are identified a the positioning of the ends of drainage networks and b the assignment of drainage directions to a dem in particular the assignment of drainage directions across flat areas and at closed depressions in the dem pits a new method for drainage network delineation is suggested which incorporates an alternative method for drainage direction assignment over a dem this method is found to produce realistic directions and performs well on two complex dems

the loess paleosol sequence of basaharc hungary revisited mollusc based paleoecological results for the middle and upper pleistocene abstract the present study discusses the findings of detailed stratigraphical sedimentological geochemical and paleoecological investigations implemented as part of a 1990 campaign to pecsi s studied profile at hungary s important danubian loess profile at basaharc in older studies there were major discrepancies between the old lithostratigraphic classifications and the numerical ages according to the findings of this study the basaharc double paleosol complex described formerly from the lower brickyard as a stratotype of middle wurmian is an isochronous heterotype of the mende upper paleosol complex from profile 1 due to reworking however the lower member of the mende upper paleosol complex must have formed not at the boundary of the upper and middle wurmian as originally presumed but during the riss wurmian interglacial conversely the upper member of this same complex developed during an interglacial between the upper and middle wurmian implying the presence of a huge erosional hiatus between the two members of the paleosol complex the genetics of the individual paleosol layers needs a re evaluation as well the majority of the soils formerly conceived to be of steppe and forest steppe origin developed among closed woodland conditions

arsenic toxicity of groundwater in parts of the bengal basin in india and bangladesh the role of quaternary stratigraphy and holocene sea level fluctuation arsenic toxicity in groundwater in the ganges delta and some low lying areas in the bengal basin is confined to middle holocene sediments dissected terraces and highlands of pleistocene and early holocene deposits are free of such problems arsenic rich pyrite or other arsenic minerals are rare or absent in the affected sediments arsenic appears to occur adsorbed on iron hydroxide coated sand grains and clay minerals and is transported in soluble form and co precipitated with or is scavenged by fe iii and mn iv in the sediments it became preferentially entrapped in fine grained and organic rich sediments during mid holocene sea level rises in deltaic and some low lying areas of the bengal basin it was liberated subsequently under reducing conditions and mediated further by microbial action intensive extraction of groundwater for irrigation and application of phosphate fertilizer possibly triggered the recent release of arsenic to groundwater this practice has induced groundwater flow mobilizing phosphate derived from fertilizer as well as from decayed organic matter which has promoted the growth of sediment biota and aided the further release of arsenic however the environment is not sufficiently reducing to mobilize iron and arsenic in groundwater in the ganges floodplains upstream of rajmahal thus arsenic toxicity in the groundwater of the bengal basin is caused by its natural setting but also appears to be triggered by recent anthropogenic activities

geomorphic expression of active tectonics in a rapidly deforming forearc sila massif calabria southern italy we examine the tectonic geomorphology of la sila calabria southern italy a high standing 1500 m plateau surrounded by crustal extension with map dem and field data these data are used to constrain a simple geodynamic model that describes short wavelength deformation of the plateau rim topographic metrics including drainage patterns river longitudinal profiles and swath profiles are consistent with field stratigraphic relationships collectively suggesting that local tectonic deformation is embedded within a broader regional uplift that has increased the mean elevation of the sila plateau during the quaternary the concavity steepness and length gradient index of modeled river longitudinal profiles proved to be the most useful metrics for recording the effects of locally active faults a previously unrecognized horst on the northeastern portion of the plateau was identified with these data nevertheless the core of the sila plateau remains relatively undeformed with respect to its flanks which are characterized by steep fault bounded escarpments active extension has dropped base level for and unloaded the plateau rim causing deep fluvial incision and associated flexural uplift of the footwall this footwall uplift helps maintain a separate external and nearly radial drainage away from the plateau along its flanks and a nearly closed drainage for the plateau interior a drainage divide roughly correlates with the plateau rim inhibiting the process of drainage integration through the sila interior and subsequent landscape dissection as a result geomorphic processes driving erosion of the sila upland are lagging behind the tectonic processes that have driven rock uplift leading to an overall increase in mean surface elevation these results underscore the importance of the lag times a landscape may endure in transforming from one tectonic and base level condition to another we conclude that the calabrian forearc has a similar geomorphic evolution as the more northern apennines consistent with the emerging view that growth of apennine topography has been recent quaternary rapid and possibly decoupled from rock deformation in the orogenic wedge

luminescence dating of periods of sand movement from the godollő hills hungary abstract a sand dune intercalated by soil horizons was investigated using luminescence and radiocarbon dating methods to determine the time of aeolian activity and soil formation in the north eastern part of the godoll hills in hungary optically stimulated luminescence osl dating and infrared stimulated luminescence irsl dating of sand sized 100 200 m grains of quartz and feldspar respectively were tested in the present study the luminescence properties of quartz were not suitable for osl dating hence irsl dating of feldspar grains was applied to all samples with subsequent correction for anomalous fading two periods of increased aeolian activity were identified in the sediment succession at tura the sediments of the lower part of the profile accumulated during the end of the late pleniglacial and through the late glacial when climatic variations caused the alternation of sand and soil horizons in the region the sand and soil layers of the upper part of the sediment succession were deposited and formed during the subatlantic phase of the holocene when sand mobility was probably mainly triggered by human activities

sulfur isotopic trends and pathways of iron sulfide formation in upper holocene sediments of the anoxic black sea down core trends for extents of iron sulfidation in upper holocene microlaminated deposits of the black sea abyssal plain imply that most of the pyrite in these sediments is formed in the sulfidic water column and or very close to the sediment water interface sulfur isotopic data for pyrite within microlaminated muds from two localities in the deep basin show striking uniformity between sites and down core with a mean 34scdt value of 37 2 0 9 1 n 18 these isotopic trends support the hypothesis of early pyrite formation isotopic compositions of pyrite sulfur in the microlaminated bottom sediments are similar to those reported for particulate reduced sulfur collected in middepth sediment traps and to 34s values for water column dissolved sulfide within a narrow zone immediately below the o2 h2s interface these three sulfur reservoirs are distinctly different from the isotopic composition of ambient dissolved sulfide of the deep water column 175 m with 34s values for the deep dissolved sulfide reservoir being consistently lower by 2 to 4 these isotopic relationships suggest that iron sulfidation is occurring dominantly within a narrow shallow region at the top of the sulfidic water mass isotopic data from a fine grained turbidite collected in the deep basin and from rapidly accumulating iron monosulfide rich muds on the anoxic upper slope are enriched in34s relative to the microlaminated deposits the enrichments on the basin margin reflect a large component of iron sulfide formed during rapid burial a broad suite of geochemical data including sulfur isotopic results are consistent with an upper slope sediment source for the ubiquitous muddy turbidites of the deep basin the collective effects of reworking transport and redeposition result in a complete conversion of avs to pyrite with little additional iron sulfidation this conclusion is supported by a detailed isotopic mass balance the present isotopic study also highlights fundamental differences in the reactivities of the iron reservoirs distributed throughout the anoxic basin sediments of the upper slope and the genetically linked turbidites of the deep basin show similar extents of iron sulfidation that are significantly lower than those of the microlaminated deposits of the deep basin floor suggesting dramatically shorter timescales of iron reactivity for the microlaminated sediments of the deep basin importantly isotopic patterns from the modern black sea should assist greatly in the recognition and interpretation of ancient anoxia in the stratigraphic record

a tectono geomorphological perspective of micro earthquake swarm activity prone areas around bhavnagar and jamnagar in saurashtra western india abstract areas around bhavnagar and jamnagar in eastern and northern parts of saurashtra respectively are identified previously as prone to recurrent earthquake swarm activity sparse seismotectonic studies so far have not revealed any linkage with known faults in bhavnagar area while no structures are known to occur in the area around jamnagar we carried out detailed tectono geomorphic studies with contrasting geomorphic settings with a view to provide an insight into the swarm activity from a geomorphological perspective the study is based on extensive field studies and quantitative geomorphic analysis of landscape and drainage the area around bhavnagar is divisible into two tectono geomorphic domains the e w trending sihor fault zone located to the west of bhavnagar domain i and the terrain to its south which shows undulating landscape controlled by n s trending structural trends domain ii the quadrant in the sw between these two domains consists of southward titled trappean hills which form source area for drainages flowing northward through sihor fault zone and those flowing eastward through domain ii late quaternary possibly holocene tectonic activity along the sihor fault is indicated by the northward tilt of alluvial plain surface knickpoint in rivers and small scale minor faults along the fault zone prominent decrease in depth of fluvial incision away from the fault zone and youthful landscape indicated by drainage basin analysis domain ii comprises the largely erosional pediplain developed over trappean and tertiary rocks to the south of bhavnagar the drainages show an early stage of landscape development due to ongoing tectonic activity the area around jamnagar is dominantly a peneplain formed over subhorizontal trappean lava flows the peneplain is a manifestation of the prolonged period of non erosion and deposition during the cenozoic the rivers show youthful landscape in the central part of the peneplain which includes large knickpoints rapids anomalous river bends steepening of channel gradient and large potholes this ene wsw trending zone of anomalous fluvial geomorphic anomalies points to the existence of a fault or fold in the subsurface the structure appears to be active as indicated by the denser cluster of earthquake swarm along this zone we infer that the generation of earthquake swarm activity comprising low to moderate magnitude shocks is caused by the sheared rocks along the sihor fault near bhavnagar and the ene wsw trending subsurface structure near lalpur which provide avenues for downward percolation of rainwater to deeper levels causing loss the frictional resistance along the weak planes

an outline of neotectonic structures and morphotectonics of the western and central pannonian basin abstract neotectonic deformation in the western and central part of the pannonian basin was investigated by means of surface and subsurface structural analyses and geomorphologic observations the applied methodology includes the study of outcrops industrial seismic profiles digital elevation models topographic maps and borehole data observations suggest that most of the neotectonic structures in the pannonian basin are related to the inverse reactivation of earlier faults formed mainly during the miocene syn and post rift phases typical structures are folds blind reverse faults and transpressional strike slip faults although normal or oblique normal faults are also present these structures significantly controlled the evolution of landforms and the drainage pattern by inducing surface upwarping and river deflections our analyses do not support the postulated tectonic origin of some landforms particularly that of the radial valley system in the western pannonian basin the most important neotectonic strike slip faults are trending to east northeast and have dextral to sinistral kinematics in the south western and central eastern part of the studied area respectively the suggested along strike change of kinematics within the same shear zones is in agreement with the fan shaped recent stress trajectories and with the present day motion of crustal blocks derived from gps data

estimating small scale snow depth and ice thickness from total freeboard for east antarctic sea ice abstract deriving the snow depth on antarctic sea ice is a key factor in estimating sea ice thickness distributions from space or airborne altimeters using a linear regression to model snow depth from observed total freeboard or the snow ice surface elevation relative to sea level is an efficient and promising method for the estimation of snow depth for instruments which only detect the uppermost surface of the sea ice conglomerate e g laser altimetry however the antarctic pack ice zone is subject to substantial variability due to synoptic scale weather forcing ice formation motion and melt undergo large spatio temporal variability throughout the year in this paper we estimate snow depth from total freeboard for the arise 2003 sipex 2007 and sipex ii 2012 research voyages to the east antarctic pack ice zone using in situ data we investigate variability in snow depth and show that for east antarctica relationships between snow depth and total freeboard vary between each voyage at a resolution of metres to tens of metres we show how regression based snow depth models track total freeboard and generally over estimate snow depth especially on highly deformed sea ice and at sites where ice freeboard makes a substantial contribution to total freeboard for a set of 3192 records we obtain an in situ mean snow depth of 0 21 m 0 19 m using a regression model derived from all in situ points we obtain the same mean with a slightly lower variability 0 16 m using voyage specific subsets of the data to derive regression models and estimate snow depth mean snow depths ranged from 0 19 m model derived from sipex observations to 0 25 m model derived from sipex ii observations while small these discrepancies impact ice thickness estimation using the assumption of hydrostatic equilibrium mean in situ ice thickness for all samples is 1 44 m 1 19 m using empirical models for snow depth ice thickness varies from 1 0 to 1 8 m with the best match to the in situ mean given when snow depth is derived using a snow depth model from all observations 1 53 m 1 55 m however mean values only tell part of the story when investigating the sea ice thickness distribution here we explicitly show how modelling snow depth and ice thickness based on a total freeboard signal compares with in situ observations this provides insight into the confidence we place in ice thickness distributions derived using a total freeboard signal and empirically derived models for snow depth

dem based morphometry of range front escarpments in attica central greece and its relation to fault slip rates in this paper we apply current geological knowledge on faulting processes to digital processing of digital elevation models dem in order to pinpoint locations of active faults the analysis is based on semiautomatic interpretation of 20 and 60 m dem and their products slope shaded relief in northern eastern attica five normal fault segments were recognized on the 20 m dem all faults strike wnw ese the faults are from west to east thriassion thfs fili fifs afidnai affs avlon avfs and pendeli pefs and range in length from 10 to 20 km all of them show geomorphic evidence for recent activity such as prominent range front escarpments v shaped valleys triangular facets and tilted footwall areas however escarpment morphometry and footwall geometry reveal systematic differences between the bexternalq segments pefs thfs and avfs and the binternalq segments affs and fifs which may be due to mechanical interaction among segments and or preexisting topography in addition transects across all five escarpments show mean scarp slope angles of 22 18f0 78 for both carbonate and metamorphic bedrock the slope angle equation for the external segments shows asymptotic behaviour with increasing height we make an empirical suggestion that slope angle is a function of the long term fault slip rate which ranges between 0 13 and 0 3 mm yr the identified faults may rupture up to magnitude 6 4 6 6 earthquakes the analysis of the 60 m dem shows a difference in fault patterns between western and northern attica which is related to crustal rheology variations d 2004 elsevier b v all rights reserved

landscape response to recent tectonic deformation in the sw pannonian basin evidence from dem based morphometric analysis of the bilogora mt area ne croatia abstract bilogora mt area is a transpressional structure located in the ne of croatia linked with the tectonic evolution of the drava depression the structure formed during pliocene and quaternary from the inversion of nw striking drava depression boundary fault which originated as a normal fault and was reactivated as a dextral strike slip fault during pliocene and quaternary time bilogora mt area underwent more than 400 m of differential uplift while still ongoing tectonic deformation is documented by historical and instrumental seismicity 3 5 m l 5 6 in this geomorphic study the recent deformation in the bilogora mt area although obscured by landscape evolution variables was assessed using dem based landscape morphometry and a set of morphometric indexes local relief and slope angle variability distributions were combined with morphometric indexes computed at the scale of the drainage basin we analyzed hypsometric curves with the hypsometric integral hi basin asymmetry af and parameters of longitudinal stream profiles c f c max l l and k sn analyzed morphometric parameters were combined into a cumulative index of relative tectonic activity rta this index summarizes drainage basin response to the possible recent tectonic activity results suggest that most of the tectonic activity is probably located along the ne front of the bilogora mt area in its nw and central part this activity could be likely related to recent tectonic activity along the kalnik mt fault zone and drava depression boundary fault zones respectively a subordinate area characterized by recent tectonic activity could be suggested within the southernmost part of the study area quaternary activity in this area is probably related to ne striking faults in vicinity of the town daruvar that continue towards the northeast into the study area though methodology presented here represents a good identification tool of possible ongoing deformation this study will be followed by detailed fieldwork and paleoseismological investigations at the identified locations

geomorphological evolution of longitudinal river profiles in the carpathians abstract the main rivers which drain the east and southeast side of the eastern carpathians and those that drain the southern carpathians have been analysed regarding the sediment transit the change of the riverbeds and the type of channel deposits in this paper attention is focused on the concavity of the stream profile on this basis we tried to determine the evolution of some carpathian rivers and thus estimate their long term evolutionary tendencies the concavity index of the east carpathian rivers shows a trend to increase from north to south from the eastern carpathians to the carpathian bend and the bucegi mountains the explanation of this situation required a review of the evolutionary stages of the eastern carpathians in order to establish the age and the evolutionary tendencies of the river network in our study area the rivers suceava moldova and bistri a have followed the same courses since the sarmathian approximately 13 5 million years ago the trotus river between 10 million and 5 4 million years ago the rivers putna buz u prahova and ialomi a suffered the most important changes so the age of their present course is about 2 5 million years the rivers could be grouped according to the mathematical model which fits best the exponential exponential logarithmic and logarithmic model finally we tried to correlate the age of the river with the form of its longitudinal profile the customary theoretical models require that the older a river is the more its concavity should increase in the headwater area and should asymptotically approach a longitudinal equilibrium profile or grade as davis calls it however the carpathian rivers do not follow this general tendency what we have demonstrated is that age had no influence on the form of the longitudinal profiles for the rivers on the exterior side of the carpathians this is because tectonic uplift was important and this phenomenon is still present today with values of over 6 mm year

geospatial technologies and digital geomorphological mapping concepts issues and research geomorphological mapping plays an essential role in understanding earth surface processes geochronology natural resources natural hazards and landscape evolution it involves the partitioning of the terrain into conceptual spatial entities based upon criteria that include morphology form genetics process composition and structure chronology environmental system associations land cover soils ecology as well as spatial topological relationships of surface features landforms historically the power of human visualization was primarily relied upon for analysis introducing subjectivity and biases with respect to selection of criteria for terrain segmentation and placement of boundaries this paper reviews new spatio temporal data and geocomputational approaches that now permit earth scientists to go far beyond traditional mapping permitting quantitative characterization of landscape morphology and the integration of varied landscape thematic information numerous conceptual theoretical and information technology issues are at the heart of digital geomorphological mapping dgm and scientific progress has not kept pace with new and rapidly evolving geospatial technologies consequently new capabilities exist but numerous issues have not been adequately addressed therefore this paper discusses conceptual foundations and illustrates how geomorphometry and mapping approaches can be used to produce geomorphological information related to the land surface and landforms process rates process form relationships and geomorphic systems

evaluation of tandem x elevation data for geomorphological mapping and interpretation in high mountain environments a case study from se tibet china abstract digital elevation models dems are a prerequisite for many different applications in the field of geomorphology in this context the two near global medium resolution dems originating from the srtm and aster missions are widely used for detailed geomorphological studies particularly in high mountain environments these datasets are however known to have substantial disadvantages beyond their posting i e data gaps and miscellaneous artifacts the upcoming tandem x dem is a promising candidate to improve this situation by application of state of the art radar technology exhibiting a posting of 12 m and less proneness to errors in this study we present a dem processed from a single tandem x cossc scene covering a study area in the extreme relief of the eastern nyainqentanglha range southeastern tibet the potential of the resulting experimental tandem x dem for geomorphological applications was evaluated by geomorphometric analyses and an assessment of landform cognoscibility and artifacts in comparison to the aster gdem and the recently released srtm 1 dem detailed geomorphological mapping was conducted for four selected core study areas in a manual approach based exclusively on the tandem x dem and its basic derivates the results show that the self processed tandem x dem yields a detailed and widely consistent landscape representation it thus fosters geomorphological analysis by visual and quantitative means allowing delineation of landforms down to footprints of 30 m even in this premature state the tandem x elevation data are widely superior to the aster and srtm datasets primarily owing to its significantly higher resolution and its lower susceptibility to artifacts that hamper landform interpretation conversely challenges toward interferometric dem generation were identified including i triangulation facets and missing topographic information resulting from radar layover on steep slopes facing toward the radar sensor ii low coherence values on leeward slopes iii decorrelation effects over water bodies and iv challenges for phase unwrapping in settings of strong topographic contrasts there is however a high probability that these drawbacks can be overcome by applying multiple interferograms exhibiting different perpendicular baselines as planned for the generation of the final tandem x dem product

neotectonic evolution of the northern laborec drainage basin northeastern part of slovakia this study investigates the influence of neotectonic activity on river and basin patterns in a mountainous area located in the northeastern part of the carpathian belt the laborecka vrchovina and bukovske vrchy mts in eastern slovakia this area evolved within the accretionary wedge of the carpathians during the neogene and it was alsowas affected by middle to late miocene thrusting of the external carpathians morphometric analysis longitudinal and transverse river valley profiles analysis of basin and valley symmetries and investigation of alluvial terraces were carried out on the northern laborec river and its tributaries this was done to detect a possible relationship between their river courses and any ongoing neotectonic activity which is otherwise difficult to detect by methods of structural geology because of the poorly exposed area the general topography of the basin is characterized by a stepwise inclination to the sw as a result of differential uplift and subsidence the reorganization of the river network in the laborec drainage basin was influenced by tectonic activity along the ne sw up to n s fault structures during the neotectonic phase pliocene quaternary the movement along these fault structures is predominantly normal to transtensive the obtained data assumes that the region is under approximately ne sw oriented sh compression and nw se trending sh tension the laborec drainage basin is characterized by a very high degree of asymmetry that sharply increases from the upper to the lower courses of the river the right bank tributaries of the laborec river are 12 km in length however the left bank tributaries such as vydra ka ol sava v rava udava and cirocha streams are up to 50 km long with a high potential of headward erosion and capturing the valley asymmetry is also very variable in the upper and lower portions of the basin based on these presented results the ancient river thalweg was located along the axis of the hostovice habura depression and it was captured by the ol sava v rava and udava streams the asymmetric pattern of the drainage basin is the result of active tectonics the continual subsidence of the transcarpathian basin and by the uplift of the laborecka vrchovina and bukovske vrchy mts these events caused rejuvenation of the headward erosion of streams in the southern part favorable lithology was also essential in the process of river capture

natural enrichment of arsenic in loch lomond sediments abstract concentrations of arsenic in surface or near surface sediment in 12 of 13 cores from the three major basins of loch lomond are substantially enhanced up to 675 mg kg compared with background values of 15 50 mg kg sedimentary as profiles are attributed to post depositional enrichment processes since there are no recent significant sources of environmental as contamination anthropogenic or natural in the loch lomond area the enrichments can be interpreted in terms of post depositional diagenetic remobilization processes in sediment reducing zones followed by upward migration of as through interstitial waters and oxidation adsorption precipitation reactions in near surface oxidizing layers confirmation of the diagenetic adsorption hypothesis is provided directly by the analysis of as species 1 5 81 g l in pore water and indirectly via comparison with sedimentary phosphorus

pyritization of trace metals in anoxic marine sediments the pyritization of reactive trace elements in different anoxic marine sediments was investigated to determine the importance of factors such as h2s reactive fe pyrite content and salinity in controlling this process the areas studied included anoxic sulfidic sediments baffin bay a hypersaline coastal lagoon from texas and green canyon a hemipelagic oil seepage area anoxic nonsulfidic sediments with high sedimentation rates atchafalaya bay mississippi delta system hemipelagic anoxic nonsulfidic sediments with low sedimentation rates gulf of mexico shelf and slope and orca basin an euxinic hypersaline basin and organic rich marsh sediments atchafalaya bay results indicate that the degree of trace metal pyritization dtmp of all trace metals except cd increased with increasing degree of pyritization dop irrespective of the type of sedimentary environment involved however for as hg and mo the dtmpdop values were generally above the 1 1 ratio line whereas the transition metals co cu mn and ni displayed a close to linear increase in dtmp with dop and moderate incorporation into pyrite chromium and the class b metals pb and zn were also gradually incorporated into the pyrite phase but without reaching the dtmp levels exhibited by the transition metals cadmium was not incorporated to a significant extent these results are consistent with the chemical attributes of these different classes of trace elements availability of dissolved trace metals and organic matter content are apparently important factors controlling the incorporation of co cr cu and ni into pyrite in anoxicsulfidic fe poor and h2s rich environments

computer assisted discrimination of morphological units on north central crete greece by applying multivariate statistics to local relief gradients traditional manual methods have been employed for decades to measure geomorphometric properties from topographic maps such measurement techniques tend to be tedious and time consuming and the designated landform elements cannot be easily overlaid on any digital map and imagery for further applied research this study deals with a new quantitative geomorphometric procedure based on the multivariate statistical analysis of local topographic gradients within a part of northcentral crete this method employs sets of computer algorithms that automatically extract and classify geomorphometric properties from digital elevation models dems this was done by evaluating the morphological setting around each pixel of the dem along the eight azimuth directions isodata unsupervised classification was implemented to generate 10 morphometric classes showing the spatial distribution of areas with a similar geomorphic scenario results revealed that this approach permitted a quick estimation of the spatial distribution of morphologically homogeneous terrain units it also demonstrated the ability of the delineated landform elements to be superimposed on any digital map and imagery for further investigation this became apparent during the examination of the relationship between the geomorphological units and the land cover land use types in the study area both relative association and the dominant land cover land use types in relation to geomorphological units are presented d 2003 elsevier b v all rights reserved

morphological response to quaternary deformation at an intermontane basin piedmont the northern tien shan kyrghyzstan abstract the tien shan is a most active intracontinental mountain building range with abundant quaternary fault related folding in order to improve our understanding of quaternary intermontane basin deformation we investigated the intermontane issyk kul lake area an anticline that was up warped through the piedmont cover causing partitioning of the alluvial fan veneer to follow the morphological scenario during the warping process we relied on surface exposed and trenched structures and on alluvial fans and bajadas as reference surfaces we used air photos and satellite images to analyze the spatial temporal morphological record and determined the age of near surface sediments by luminescence dating we demonstrate that the up warped ak teke hills are a thrust generated subdued anticline with strong morphological asymmetry which results from the coupling of the competing processes of up warp and erosional feedback the active creeks across the up warped anticline indicate that the antecedent drainage system kept pace with the rate of uplift the rivers which once sourced the piedmont like the toru aygyr kultor and the dyuresu became deeply entrenched and gradually transformed the study area into an abandoned morphological surface the up warp caused local lateral drainage diversion in front of the northern backlimb and triggered the formation of a dendritic drainage pattern upfan luminescence dating suggest that the period of up warp and antecedent entrenchment started after 157 ka the morphologically mature study area demonstrates the response of fluvial systems to growing folds on piedmont areas induced by a propagating frontal fold at a thrust belt edge following shortening

discrimination of fluvial and eolian features on large ignimbrite sheets around la pacana caldera chile using landsat and srtm derived dem abstract satellite images and ground based observations were used to investigate the morphology and origin of valleys and ridges across large ignimbrite provinces around la pacana caldera n chile we studied 12 separate sites that included five different ignimbrite units that range in age from 5 6 0 5 ma to 1 35 0 15 ma over 400 features from within these study sites were quantified study sites typically have dimensions of 25 35 km measurements were made using landsat tm etm and srtm derived dem and shaded relief images morphological measurements were made of the ridges and channels including the direction of regional slope length orientation and gradient of each feature a classification of the different ignimbrite erosion influences resulting in varying landscape morphologies identified 4 landscape types fluvial eolian modified and complex we conclude that the most prevalent features are fluvial derived channels but the most distinctive are linear wind derived ridges the orientation of these ridges suggests that strong uni directional winds from the northwest have been constant over a long period of time 1 my

arsenic incorporation into authigenic pyrite bengal basin sediment bangladesh abstract sediment from two deep boreholes 400 m approximately 90 km apart in southern bangladesh was analyzed by x ray absorption spectroscopy xas total chemical analyses chemical extractions and electron probe microanalysis to establish the importance of authigenic pyrite as a sink for arsenic in the bengal basin authigenic framboidal and massive pyrite median values 1500 and 3200 ppm as respectively is the principal arsenic residence in sediment from both boreholes although pyrite is dominant ferric oxyhydroxides and secondary iron phases contain a large fraction of the sediment bound arsenic between approximately 20 and 100 m which is the depth range of wells containing the greatest amount of dissolved arsenic the lack of pyrite in this interval is attributed to rapid sediment deposition and a low sulfur flux from riverine and atmospheric sources the ability of deeper aquifers 150 m to produce ground water with low dissolved arsenic in southern bangladesh reflects adequate sulfur supplies and sufficient time to redistribute the arsenic into pyrite during diagenesis

stress induced late stage subsidence anomalies in the pannonian basin abstract subsidence sedimentation and tectonic quiescence of the pannonian basin was interrupted a few million years ago by tectonic reactivation this recent activity has manifested itself in uplift of the western and eastern flanks and continuing subsidence of the central part of the pannonian basin low to medium magnitude earthquakes of the carpathian pannonian region are generated mostly in the upper crust by reverse and wrench fault mechanisms there is no evidence for earthquakes of extensional origin 2 d model calculation of the subsidence history shows that a recent increase in magnitude of horizontal compressional intraplate stress can explain fairly well the observed quaternary uplift and subsidence pattern we propose that this stress increase is caused by the overall europe africa convergence in late pliocene consumption of subductible lithosphere at the eastern margin of the pannonian basin was completed and the lithosphere underlying the pannonian basin became locked in a stable continental frame consequently extensional basin formation has come to an end and compressional inversion of the pannonian basin is in progress

fossil plants from the eocene london clay the use of pyrite textures to determine the mechanism of pyritization pyritized twigs and roots from the eocene london clay of se england were studied to gain a better understanding of the process of pyritization by investigating pyrite textures in relation to cell type and quality of preservation highly polished sections and fractured surfaces taken from 124 specimens were examined using optical microscope and sem the latter equipped to map pyrite and carbon pyrite textures include microcrystalline framboidal massive polycrystalline and subhedral or euhedral forms the highest fidelity of preservation is always associated with microcrystalline pyrite precipitation on wall surfaces with subsequent infilling of cells with framboids or polyhedra preventing compression during burial but contributing nothing to actual ultrastructural preservation ultrastructurally parenchymatous cell walls are coalified whereas microcrystalline pyrite plus coalified material were observed within lignified cell walls in all four stages of pyritization are documented observations are interpreted in the light of recent experiments on pyritization of living material and the chemistry of pyrite formation in anoxic environments involving an aqueous and hence mobile fes cluster complex as a precursor the complexity of the fossilization process is reflected in the presence of different textures in adjacent cells of the same tissue this demonstrates the development of isolated chemical microenvironments as ph and eh vary in response to decay and mineralization and pyrite overgrowths within a cell indicate local microenvironmental changes through time

characterization of volcanic geomorphology and geology by slope and topographic openness abstract we used a digital elevation model dem of iwate volcano japan to calculate slope and topographic openness for every geological unit in that area further we conducted principal component analysis pca and stepwise discriminant analysis sda to evaluate statistical differences in the morphometric parameters of the geological units we categorized the geological units according to their ages and their formation processes the categorization based on formation processes was as follows lava flow lava central cone stratocone air fall deposit pyroclastic flow deposit volcanic fan deposit and debris avalanche deposit pca allowed us to select geological units suitable for analysis while sda was used to select some morphometric parameters which could explain the differences in the formation processes and ages of the geological units we found that the formation processes correspond well to mean slope and that the geological ages that control the degree of surface dissection correspond well to the standard deviations of slope and negative topographic openness

the environmental significance of ventifacts a critical review abstract ventifacts wind abraded clasts or rock surfaces are common features of many terrestrial hot and cold deserts coastal periglacial and mountain environments as well as on mars and have a long history of investigation this review paper discusses some of the main themes in terrestrial ventifact research including their formation and geomorphic controls the varied morphological forms of ventifacts in terrestrial environments and their environmental significance as indicators of past and present wind direction and sediment mobility are critically evaluated future research directions are identified

yardangs in the semiarid central sector of the ebro depression ne spain abstract this work reveals the existence of yardangs in the central sector of the semiarid ebro depression of spain almost all the documented yardang fields are located in extreme arid environments the yardangs are developed in horizontal tertiary gypsum and limestone more than 100 closed depressions solution dolines have been formed in the soluble sediments of this area some of them hosting saline lakes or playas all the yardangs occur on the leeward margin of the larger playas and their mean orientation n122e coincides with the prevalent direction of the strong local wind called cierzo two main types of yardang have been identified 44 rock yardangs formed in the miocene bedrock and six yardangs developed in unconsolidated lacustrine deposits nebkha dunes have been recognized and yardang like morphologies in building rubble accumulations on the floor of a playa

geomorphic evidence of active deformation and uplift in a modern continental wedge top foredeep transition example of the eastern ecuadorian andes abstract the eastern ecuadorian andes appear as a fold and thrust belt adjacent to a continental foredeep represented by one of the world s largest tropical alluvial megafans the pastaza megafan debouching into the amazonian lowland the apex of the pliocene pleistocene megafan situated in the present day wedge top subandean zone has been cut by an erosion surface the western part of which has been uplifted of 500 m along the frontal thrust forming a poorly dissected plateau the mera plateau this erosion surface erased most of the previous fluvial landscape but preserved a large thrust related anticlinal hinge deforming less erodible underlying strata the mirador fold and smaller sized anticlines this surface has been then incised by two antecedent major rivers the pastaza and the napo and few tributaries the plateau edge is marked by a series of large scale gently sloping landslides clustered along a 70 km long concave eastward line associated with the frontal thrust fault the newly formed immature rivers issued from the landslides or sourced within east dipping remnants of the erosion surface downstream of the landslide line constitute the greatest part of the streams feeding the ecuadorian amazonian basin at 70 to 100 km from the landslide line the drainage abruptly changes from highly immature to mature with a well defined hinge line representing the outer limit of landslide and tectonic control the diversions of the pastaza river indicate ongoing fold growth since at least the late pleistocene in the eastern cordillera and the early holocene in the mera plateau the preserved terraces of the pastaza valley are all degradational and are ascribed to periods of tectonic seismic activity alternating with periods of tectonic quiescence or decreased seismic activity rather than to climatic events 14c dating of the plateau erosion surface and of the upper pastaza terraces indicates that the minimum average incision rate since 18 000 years bp varies locally in the upper pastaza valley from 0 5 to 0 67 cm year 1 increasing from 18 000 years bp to now a comparison of these incision rates with fold and thrust fault uplift rates indicates that incision in the upper pastaza valley was a result of rapid uplift up to 1 cm year 1 along the mirador fold and thrust which caused a restoration of the local equilibrium profile of the upper reach combined with smaller local fault uplift along the westernmost thrust faults the uplift of the whole mera plateau with respect to the upper amazonian basin gives a minimum average uplift rate of 2 8 cm year 1 since 18 000 years bp the overall uplift of the mera plateau and the eastern cordillera is likely to have been caused by a regional scale low angle thrust ramp emerging as the frontal thrust fault

structurally controlled drainage basin development in the south of menorca western mediterranean spain abstract the south of menorca consists of a gently folded upper miocene carbonate platform over which a drainage system has developed three areas with different drainage characteristics have been delimited the central area the eastern area and the western area the central area is characterised by deep streams with steep slopes whereas the western and eastern areas have slightly incised streams with gentle slopes the drainage development has been controlled by the inversion of a normal fault in pliocene times resulting in a wide anticline with a nne ssw orientation the deep streams of the central area follow the faults associated with this anticline the amount of incision achieved by these streams depends on the proportion of impermeable rocks exposed in the drainage basin the streams draining basins with a large proportion of impervious rocks have concave longitudinal profiles whereas those from catchments with a smaller area of impermeable materials have concave convex profiles streams with minor incision are found in the western and eastern areas of the carbonate platform given that their drainage basins are constituted by permeable materials

the mid hungarian line a zone of repeated tectonic inversions abstract the mid hungarian line is a major tectonic feature of the intra carpathian area separating two terranes of different origin and tectonic structure although this tectonic line was known from borehole records it has not been described in seismic sections the study presents interpreted seismic lines crossing the supposed trace of the mid hungarian line these seismic sections show north dipping normal faults and thrust faults as well as cross cutting young strike slip faults a complex tectonic history is deduced including intra oligocene early miocene thrusting middle miocene extension local late miocene inversion and late miocene pliocene normal faulting and left lateral wrenching in the light of our seismic study we think that the best candidate for the mid hungarian line is a north dipping detachment fault beneath large masses of neogene volcanics the auxiliary structures to the north seen on seismic sections suggest that it moved as a south vergent thrust fault during the palaeogene early miocene which later was reactivated as a set of normal faults the northern alcapa unit overrode the southern tisza dacia unit along this fault zone the same relative positions are observed in the northern termination of the line other structures along the supposed trace of the line are north dipping normal or strike slip faults which frequently were reactivated as smaller thrust faults during the late neogene palaeogene early miocene thrusting along the line might be the result of the opposite tertiary rotations of the two major units as suggested by palaeomagnetic measurements and earlier models

testing the tectonic significance of some parameters of longitudinal river profiles the case of the ardenne belgium nw europe the longitudinal profiles of 24 rivers of 3rd to 5th order have been analyzed in order to recognize the regional tectonic differentiation pattern of the ardenne a paleozoic massif of nw europe data collected exclusively from 1 25 000 topographic maps were used to define a set of parameters related to the geometry of the profile and proxies for river bedload and drainage area validation of the proxy defined for the bedload discharge ratio demonstrates its potential use for inter river comparison based on its value at the river mouth it is however inadequate to estimate the ratio changes along a given stream course this proxy has been computed to estimate the portion accounted for by hydrodynamic factors in the river bed profiling thus outliers to the correlation function linking it to the river bed gradient have been considered as undergoing other influences principally of lithologic or tectonic origin most indicative of the computed profile parameters are those related to the concavity of the profile four more or less regional longitudinal profile types are recognized which are partly determined by differential tectonic movement the combined analysis of all the parameters confirms the current uplift of the ne ardenne and points to a subsidence of the namur area with respect to its sw and se surroundings whether periglacial or tectonic in origin the upper pleistocene lowering of a local base level has also been identified in the famenne another conclusion of this study is that in order to evidence tectonic influences and to avoid any misinterpretation in a region of complex geologic and geomorphic history and moderate tectonic activity it is essential to consider a number of parameters and to consider their significance within the framework of detailed geologic setting and morphogenetic history

natural arsenic contamination of holocene alluvial aquifers by linked tectonic weathering and microbial processes 1 linked tectonic geochemical and biologic processes lead to natural arsenic contamination of groundwater in holocene alluvial aquifers which are the main threat to human health around the world these groundwaters are commonly found a long distance from their ultimate source of arsenic where chemical weathering of as bearing minerals occurs we propose a gbh as model that ties together all of the important tectonic biologic and hydrologic processes that cause natural as release in groundwater in holocene terrestrial deposits processes highlighted by the gbh as model can explain the movement of arsenic from lithosphere to hydrosphere however we propose a factor that has increased dissolved as concentrations in holocene aquifers to levels where human health is threatened mechanical weathering associated with pleistocene glaciation our model invokes erosion of mountain belts aided by glaciers transport of arsenic by surface waters adsorption of as by stream sediments and deposition of stream sediments and organic matter in alluvial deposits subsequently fe iii reducing bacteria present in alluvial aquifers cause the release of sorbed as to groundwater under moderately reducing conditions

mechanism of regional enrichment of groundwater by boron the examples of bangladesh and michigan usa abstract in bangladesh concentrations of boron in groundwater reach 2 1 mg l 1 and are high regionally in alluvial aquifers of late pleistocene holocene age concentrations exceed 0 5 mg l 1 across approximately 6700 km 2 of the deep aquifer 150 m depth and 3000 km 2 of the shallow aquifer 1 and high values are widespread in the ne of the county these concentrations exceed the regulatory guideline values for human consumption of 0 5 mg l 1 who or 0 9 mg l 1 usa the boron has desorbed from mineral surfaces as freshwater flushing displaces saline waters from the aquifers in bangladesh desorption is driven by decreasing ionic strength the equilibrium re adjustment of mineral sorption sites to the low boron concentration in freshwater and competitive exchange with hco 3 co 3 in deep bangladesh aquifers in barisal district 250 m deep boron enrichment delineates a buried estuary marking a previous course of the ganges and or brahmaputra rivers boron enrichment is accompanied by ion exchange that depletes ca and enriches na in the flushing freshwater the patterns of enrichment and depletion indicate the direction of water quality change in terms of salinization or freshening with greater sensitivity than absolute chemical parameters

geomorphic and sedimentary response of rivers to tectonic deformation a brief review and critique of a tool for recognizing subtle epeirogenic deformation in modern and ancient settings abstract rivers are extremely sensitive to subtle changes in their grade caused by tectonic tilting as such recognition of tectonic tilting effects on rivers and their resultant sediments can be a useful tool for identifying the often cryptic warping associated with incipient and smaller scale epeirogenic deformation in both modern and ancient settings tectonic warping may result in either longitudinal parallel to floodplain orientation or lateral normal to floodplain orientation tilting of alluvial river profiles alluvial rivers may respond to deformation of longitudinal profile by 1 deflection around zones of uplift and into zones of subsidence 2 aggradation in backtilted and degradation in foretilted reaches 3 compensation of slope alteration by shifts in channel pattern 4 increase in frequency of overbank flooding for foretilted and decrease for backtilted reaches and 5 increased bedload grain size in foretilted reaches and decreased bedload grain size in backtilted reaches lateral tilting causes down tilt avulsion of streams where tilt rates are high and steady down tilt migration combing where tilt rates are lower each of the above effects may have profound impacts on lithofacies geometry and distribution that may potentially be preserved in the rock record fluvial sedimentary evidence for past tilting is traditionally based on the assumption that depositional features reminiscent of modern fluvial tectonic effects are evidence for past tectonic effects where it is closely associated with historically active structures or where non tectonic causes cannot be invoked however caution must be exercised when using these effects as criteria for past or current tectonic warping as these effects may be caused by non tectonic factors these non tectonic causes must be eliminated before tectonic interpretations are made

wind erosion under cold climate a pleistocene periglacial mega yardang system in central europe western pannonian basin hungary abstract mega yardangs are known to form under extremely arid warm or in some instances moderate climates here we report on the mega yardang field of the pannonian basin hungary which was uniquely formed under periglacial probably semi arid conditions and discuss its implications on factors controlling yardang formation in general the yardang field is composed of advanced streamlined forms and of less aerodynamic ridges separated by well developed corridors the length of the largest features exceeds 60 km their height varies around 150 m together with ventifacts deflation hollows and wind blown sand areas the yardang field is part of an integrated eolian feature system driven by northerly to northwesterly winds dating of ventifact surfaces with in situ produced cosmogenic nuclides places the onset of significant wind erosion to the early pleistocene 1 5 ma osl dated young loess from which well developed yardangs were sculpted and wind blown sands show that eolian action continued until the early holocene the long temporal range of wind erosion compared to average yardang formation rates and the rarity of advanced yardang forms indicate intermittent and relatively short most probably millennial scale deflation periods since the early holocene the system has been inactive and demonstrates that yardangs can persist in a recognizable form for several millennia even under less arid conditions the main control on yardang formation appears to be the existence of strong unidirectional winds in the pannonian basin facilitated mainly by the channeling effect of topographic lows in the surrounding mountain chains yardangs can form even under semi arid climates however the rarity of these occurrences suggests that this requires a special association of environmental conditions yardang formation is facilitated by homogeneous lithology namely by widespread weakly consolidated sandy sediments the distribution of yardang fields is controlled by vertical neotectonic movements which provided uplifted areas to be sculptured and topographic obstacles that sheltered downwind sediments faulting can be excluded as a controlling factor in mega yardang formation nor is the role of jointing supported

the significance of large sediment supply active tectonism and eustasy on margin sequence development late quaternary stratigraphy and evolution of the ganges brahmaputra delta abstract borehole data from the ganges brahmaputra delta system unveil an intriguing late quaternary history controlled by immense sediment discharge tectonics and eustasy sea level first intersected a major portion of the lowstand surface 10 000 11 000 cal yr bp marking the onset of sediment trapping and delta growth despite rapid sea level rise 1 cm yr sediment load was sufficient to maintain relative shoreline stability during this time by 7000 cal yr bp accommodation was quickly infilled with slowed sea level rise leading to upstream channel migration and widespread dispersal of sands this forced coastal progradation along the western delta front where the ganges was situated and much of the river s fine grained discharge bypassed the subaerial delta and formed a prograding deltaic clinoform on the shelf concurrently brahmaputra sediments were sequestered to an inland tectonic basin thus starving the adjacent shoreline and leading to transgression along the eastern delta by 5000 cal yr bp the two rivers had migrated or changed course to discharge along the eastern delta shoreline which began to prograde into what is now the modern river mouth estuary present delta configuration appears to have developed by 3000 cal yr bp evolution of the tectonically active ganges brahmaputra g b system reveals important similarities and differences with other deltas overall facies succession follows that of basic models progressing from an alluvial valley to coastal marine delta front to a prograding subaerial delta plain however the timing thickness and controls of these deposits differ immense sediment discharge from the ganges and brahmaputra rivers allowed initial delta growth 2000 3000 yr earlier than the global average despite debouching onto a canyon incised high energy margin subsequently a thick 50 m transgressive systems tract was formed during the early holocene phase of delta aggradation contrasting with extensive shoreline retreat documented along most margins highstand progradation of coastal and shelf sequences ensued by the middle holocene but subsiding inland basins also favored accumulation of a thick to 40 m highstand sequence in the lower floodplains unlike many other delta systems subsidence in the subaerial g b delta is not dominated by compaction but rather by plate driven tectonic processes that generate rates up to 4 mm year overall the huge sediment load tectonic subsidence major seismic events and a nearshore canyon system have led to widespread sediment dispersal and sequence formation across the subaerial delta shelf and deep sea bengal fan throughout the late quaternary

coupling erosion and topographic development in the rainiest place on earth reconstructing the shillong plateau uplift history with in situ cosmogenic 10 be abstract the uplift of the shillong plateau in northeast india between the bengal floodplain and the himalaya mountains has had a significant impact on regional precipitation patterns strain partitioning and the path of the brahmaputra river today the plateau receives the highest measured yearly rainfall in the world and is tectonically active having hosted one of the strongest intra plate earthquakes ever recorded despite the unique tectonic and climatic setting of this prominent landscape feature its exhumation and surface uplift history are poorly constrained we collected 14 detrital river sand and 3 bedrock samples from the southern margin of the shillong plateau to measure erosion rates using the terrestrial cosmogenic nuclide 10be the calculated bedrock erosion rates range from 2 0 to 5 6 m my 1 whereas catchment average erosion rates from detrital river sands range from 48 to 214 m my 1 these rates are surprisingly low in the context of steep tectonically active slopes and extreme rainfall moreover the highest among these rates which occur on the low relief plateau surface appear to have been affected by anthropogenic land use change to determine the onset of surface uplift we coupled the catchment averaged erosion rates with topographic analyses of the plateau s southern margin we interpolated an inclined pre incision surface from minimally eroded remnants along the valley interfluves and calculated the eroded volume of the valleys carved beneath the surface the missing volume was then divided by the volume flux derived from the erosion rates to obtain the onset of uplift the results of this calculation ranging from 3 0 to 5 0 ma for individual valleys are in agreement with several lines of stratigraphic evidence from the brahmaputra and bengal basin that constrain the onset of topographic uplift specifically the onset of flexural loading and the transgression from deltaic to marine deposition ultimately our data corroborate the hypothesis that surface uplift was decoupled from the onset of rapid exhumation which occurred several millions of years earlier

tectonic geomorphology of the serrania de san lucas central cordillera regional implications for active tectonics and drainage rearrangement in the northern andes abstract we explore the structural and geomorphological evidence for recent tectonic activity in the serrania de san lucas san lucas range slr the northern segment of the central cordillera in the colombian northern andes a morphostructural and geomorphological analysis was carried out in this isolated range using several topographic metrics like the local relief slope variability hypsometric integral swath profiles normalised concavity steepness ksn drainage basin shape index bs asymmetry factor af mountain front sinuosity smf and the ratio of valley floor width to valley floor height vf after remote sensing and geological analysis of the structural pattern we propose that the slr represents a horse tail termination of the palestina fault that seems to have reactivated in the miocene pliocene in a transpressive stress state during the andean orogeny based on this structural model and the geomorphic indices we divided the slr into two regional domains the simiti domain in the east and the palestina domain in the west the simiti domain is dominated by ne sw striking structures with a right lateral kinematic whereas the palestina domain is controlled by the n s right lateral palestina fault which is the predominant structure in the slr we demonstrate that recent tectonic activity and higher uplift rates have been preferably constrained to the simiti domain to the north of the simiti san blas faults along the ne sw striking faults in this area low smf and vf values suggest an active mountain front bounded by the reverse morales fault and quaternary uplift rates between 0 05 and 0 5 mm yr on the other hand the quaternary tectonic activity in the palestina domain was concentrated in the northern portion where climate has also played a significant role in controlling denudation rates and landscape evolution the variable uplift pattern between both domains has induced along strike changes in divide mobility and timing of drainage reorganisation within the slr discrete capture events forced a west southwest migration of the eastern side towards the western side of the slr the concentrated highest tectonic activity in the simiti domain progressively modified the topographic conditions and triggered the divide migration event our findings provide new and valuable information on the active tectonics and neogene to quaternary landscape evolution in this poorly studied area in the northern andes

semi automated mapping of landforms using multiple point geostatistics abstract this study presents an application of a multiple point geostatistics mps to map landforms mps uses information at multiple cell locations including morphometric attributes at a target mapping cell i e digital elevation model dem derivatives and non morphometric attributes i e landforms at the neighboring cells to determine the landform the technique requires a training data set consisting of a field map of landforms and a dem mapping landforms proceeds in two main steps first the number of cells per landform class associated with a set of observed attributes discretized into classes e g slope class is retrieved from the training image and stored in a frequency tree which is a hierarchical database second the algorithm visits the non mapped cells and assigns to these a realization of a landform class based on the probability function of landforms conditioned to the observed attributes as retrieved from the frequency tree the approach was tested using a data set for the buech catchment in the french alps we used four morphometric attributes extracted from a 37 5 m resolution dem as well as two non morphometric attributes observed in the neighborhood the training data set was taken from multiple locations covering 10 of the total area the mapping was performed in a stochastic framework in which 35 map realizations were generated and used to derive the probabilistic map of landforms based on this configuration the technique yielded a map with 51 2 of correct cells evaluated against the field map of landforms the mapping accuracy is relatively high at high elevations compared to the mid slope and low lying areas debris slope was mapped with the highest accuracy while mps shows a low capability in mapping hogback and glacis the mapping accuracy is highest for training areas with a size of 7 5 10 of the total area reducing the size of the training images resulted in a decreased mapping quality as the frequency database only represents local characteristics of landforms that are not representative for the remaining area mps outperforms a rule based technique that only uses the morphometric attributes at the target mapping cell in the classification i e one point statistics technique by 15 of cell accuracy

discrimination of fluvial eolian and neotectonic features in a low hilly landscape a dem based morphotectonic analysis in the central pannonian basin hungary abstract the godoll hills a low relief terrain within the central pannonian basin in hungary is characterised by moderate tectonic deformation rates although typical tectonic landforms are not clearly recognisable in the study area this paper succeeded in discriminating between tectonically controlled landforms and features shaped by fluvial erosion or deflation with no tectonic control dem based morphometric parameters including elevation slope and surface roughness enabled the delineation of two nw se trending spearhead shaped ridges separated by a wide rectilinear valley of the same strike although directional statistics suggested possible tectonic control of nw se striking landforms precise morphometry completed with an analysis of subsurface structures rejected their tectonic preformation deflation plays a significant role in shaping the area and the presence of two large scale yardangs separated by a wind channel is proposed in temperate continental areas of europe no deflational landforms of such scale have been described so far suggesting that pleistocene wind power in periglacial areas was more significant than it was previously thought characteristic drainage patterns and longitudinal valley profiles enabled the recognition of areas probably affected by neotectonic deformation a good agreement was observed between locations of quaternary warping predicted by the morphometric study and subsurface structures revealed by the tectonic analysis zones of surface uplift and subsidence corresponded to anticlinal and synclinal hinges of fault related folds in low relief and slowly deforming areas where exogenous forces may override tectonic deformation only the integrated application of morphometric and subsurface structural indications could assure correct interpretation of the origin of various landforms while a morphometric study alone could have led to misinterpretation of some morphometric indices apparently suggesting tectonic preformation on the other hand the described morphological expression of subsurface structures could verify quaternary age of the deformation