quantitative analysis of insar digital elevation models for identification of areas with different tectonic activities in southern italy this work presents the results of a quantitative analysis of an interferometric sar insar digital elevation model dem obtained by the shuttle radar topography mission srtm the analysis aims to identify additional parameters to recognize areas in southern italy with different tectonic activities and behaviours the axial zone of the campania lucania apennine and the sila massif in calabria italy characterized by quite different evolutionary histories have been chosen as test areas sufficiently wide to validate observations on a sub regional scale at least geomorphological information on the shape of palaeosurfaces has been used to estimate uplift and or erosion amounts and rates palaeosurfaces are identified on the dem as regions with an altitude higher than 1000 m a s l and sub planar land surfaces dipping less than 6 information about the shape of palaeosurfaces during the first stage of uplift and before the tectonic induced block fragmentation has been extracted a fragmentation index has been computed for these erosional surfaces the first stage of this landscape evolution has been studied in terms of the geometric characteristics of fragmented blocks the last erosional stage has been recognized in terms of both geometric characteristics and fragmentation index of the sub horizontal land surfaces altitude and age of the palaeosurfaces referred to ancient base levels of the erosion have been used to estimate the erosional rate copyright 2008 john wiley and sons ltd

geochemical evolution of groundwater in the cambrian vendian aquifer system of the baltic basin abstract the shallowly buried marginal part of the cambrian vendian confined aquifer system of the baltic basin is characterised by fresh and low 18 o composition water whereas the deeply settled parts of the aquifer are characterized by typical na ca cl basinal brines spatial variation in water geochemistry and stable isotope composition suggests mixing origin of the diluted water of three end members glacial melt water of the weichselian ice age 115 000 10 000 bp na ca cl composition basin brine and modern meteoric water the mixing has occurred in two stages first the intrusion and mixing of isotopically depleted glacial waters with basinal brines occurred during the pleistocene glacial periods when the subglacial melt water with high hydraulic gradient penetrated into the aquifer the second stage of mixing takes place nowadays by intrusion of meteoric waters the freshened water at the northern margin of the basin has acquired a partial equilibrium with the weakly cemented rock matrix of the aquifer

resistivity imaging reveals complex pattern of saltwater intrusion along monterey coast abstract electrical resistivity tomography data were acquired along 40 km of the monterey bay coast in central california these data resulted in electrical resistivity images to depths of approximately 280 m b s l which were used to understand the distribution of freshwater and saltwater in the subsurface and factors controlling this distribution the resulting resistivity sections were interpreted in conjunction with existing data sets including well logs seismic reflection data geologic reports hydrologic reports and land use maps from the region interpretation of these data shows a complex pattern of saltwater intrusion resulting from geology pumping and recharge the resistivity profiles were used to identify geological flow conduits and barriers such as palaeo channels and faults localized saltwater intrusion from individual pumping wells infiltration zones of surface fresh and brackish water and regions showing improvements in water quality due to management actions the use of ert data for characterizing the subsurface in this region has led to an understanding of the spatial distribution of freshwater and saltwater at a level of detail unattainable with the previously deployed traditional well based salinity mapping and monitoring techniques alone significant spatial variability in the extent and geometry of intrusion observed in the acquired data highlights the importance of adopting continuous subsurface characterization methods such as this one

contribution of structural analysis to understanding the geodynamic evolution of the calabrian arc southern italy abstract a marked curvature of crustal structures characterizes the calabrian arc in southern italy the overall deformation of the arc seems mostly controlled by the sangineto shear zone to the north and by the mt kumeta alcantara shear zone to the south which both separate different crustal sectors other important fault systems cut the iblean foreland scicli ragusa fault zone and many others dissect the crystalline units of central calabria neotectonic structural analyses have been carried out in order to recognize the character of the plio pleistocene tectonic phases and their bearing on the present configuration of the arc after the middle miocene extensional phase an early middle pliocene compressional phase is detectable in many parts of the arc right and left lateral displacements respectively characterize the mt kumeta alcantara and sangineto shear zones and right lateral movements are also detectable within the scicli ragusa fault system finally the pleistocene tensional regime seems to have been controlled mainly by uplift the structural and neotectonic data allow us to propose a model of the recent evolution of the arc which was bent mainly as a result of opposed wrench faulting along the sangineto and mt kumeta alcantara shear zones

the long term denudation rate in the southern apennines chain italy a gis aided estimation of the rock volumes eroded since middle pleistocene time abstract the long term denudation rate has been evaluated within an actively deforming area the southern apennines chain using both geomorphological and gis aided analysis of a 2738 km 2 representative sample area the rock volume contained between a reconstructed palaeotopography and the present topography of the study area has been calculated palaeotopography has been reconstructed on the basis of the relics of an irregular surface whose tentative age is 0 8 0 6 ma and also includes remnants of a more ancient more suspended and badly preserved palaeosurface to represent the modern topography a certified dtm of italy with grid 230 230 m 2 was adopted the calculated rock volume eroded since the beginning of the dissection of the palaeosurface is 478 km 3 which implies an average erosional downwearing of 175 m however downwearing is not uniformly distributed over the area as it is concentrated along valleys in particular the same major valley trunks that already existed at the beginning of the middle pleistocene show downcutting amounting to 400 m and more while the amount of erosion on the divide areas is of the order of a few tens of metres the resulting mean denudation rate falls between 0 22 and 0 30 mm a

origin and chemical evolution of formation waters from silurian devonian strata in the illinois basin usa abstract a suite of formation water samples from silurian devonian reservoirs in the illinois basin has been analyzed for major minor and trace element concentrations and for h o and sr isotopic compositions in order to interpret origin of salinity and geochemical evolution of brine compositions in this evaporite and shale poor cratonic basin although chloride concentrations range from 2000 to 137 000 mg l cl br ratios 291 18 are consistent with those of seawater or seawater evaporated short of halite saturation cl br 292 thus during silurian devonian time subaerially evaporated penesaline brine entered the subsurface where it was chemically modified through brine rock interactions cation br ratios and mineralogy of associated strata indicate that na and k were depleted through interaction with clay minerals ca was enriched and mg depleted by dolomitization and sr was enriched as a result of caco3 recrystallization and dolomitization although significant dilution of the modified brine with meteoric water is supported by d 18o covariance original marine waters have not been completely expelled from silurian devonian strata hydrogen and oxygen isotopes exhibit covariant relations with cation and anion concentrations implying that isotopic exchange between h2o and minerals has not greatly influenced the d 18o trend brine 87 sr 86 sr ratios range from 0 7092 to 0 7108 when these ratios are plotted versus 1 sr a two component mixing trend is suggested although sr concentrations have experienced local diagenetic modification a 87sr enriched fluid may have accompanied petroleum migration from new albany shales into adjacent silurian devonian carbonates where it mixed with remnant evaporated seawater this event probably preceded the influx of meteoric water as gdd and 18o are not correlated with sr isotopic compositions of formation waters

stratigraphic and structural relationships between meso cenozoic lagonegro basin and coeval carbonate platforms in southern apennines italy abstract stratigraphic studies and facies analysis integrated with a new geological and structural survey of the meso cenozoic units outcropping in the campania lucania apennines southern italy allowed us to restore the palaeogeographic pattern and the tectonic evolution of the chain during oligo miocene times the southern apennines are a n150 striking and ne verging fold and thrust belt mainly derived from the deformation of the african apulian passive margin four wide belts with different features have been recognized in the chain area from east to west the following units outcrop a successions characterized by basinal to marginal facies ranging in age from cretaceous to miocene tectonically lying on plio pleistocene foredeep deposits b successions characterized by shallow water basinal and shelf margin facies ranging in age from middle triassic to miocene lagonegro units overthrust on the previous ones c triassic to miocene carbonate platform successions apenninic platform units overthrust on the lagonegro units d jurassic cretaceous to miocene deep water successions ophiolite bearing or internal units and associated siliciclastic wedges outcropping along the tyrrhenian belt and the calabria lucania boundary overthrust on the apenninic platform units all these units tectonically lie on the buried apulian platform which is covered at least in the eastern sector of the chain by pliocene to pleistocene foredeep deposits stratigraphic patterns of the cretaceous to lower miocene lagonegro successions are coherent with the platform margin ones calcareous clastics of the lagonegro basin are in fact supplied by an adjacent western platform as inferred by several sedimentological evidences slump and palaeocurrent directions and decreasing grain size towards the depocentre of the basin tectonic relationships among the different units of the chain with particular emphasis on the lagonegro and apenninic platform units of the lucanian segment are shown by means of both regional and detailed geological cross sections the lagonegro units constantly underlie the carbonate units originating from detachment and thrusting of the western platform and overlie the eastern i e apulian platform the lagonegro units show a strong lateral variability of map scale structures dome and basin folds are in fact largely observable in the lucanian apennine further the belt is widely affected by plio quaternary strike slip and extensional faults yet excluding the brittle deformation due to quaternary faulting the complexity of structural styles seems to result from the neogene refolding of more ancient structures produced by oligo miocene intraplate deformation this hypothesis is supported by two independent lines of evidence the first is the recognition of unconformities between the lower miocene numidian sandstone and the underlying lagonegro successions at least in the southwestern sectors the second is that the internal i e western platform remains undeformed until the early miocene both stratigraphic and structural data suggest an external position of the meso cenozoic lagonegro basin with regard to the coeval apenninic platform

geochemistry and isotope chemistry of michigan basin brines devonian formations detailed chemical and isotope analysis of 87 formation waters collected from six devonian aged units in the michigan basin are presented and discussed in terms of the origin of the dissolved components and the water total dissolved solids in these waters range from 200 000 to 400 000mg 1 upper devonian formations produce dominantly nacacl brine while deeper formations produce canacl water ratios of cl br and na br along with divalent cation content mcl2 indicate that these brines are derived from evapo concentrated seawater other ion concentrations appear to be extensively modified from seawater values by water rock reactions the most important reactions are dolomitization which explains the ca content of the brines and reactions involving aluminosilicate minerals stable isotope 18o and d compositions indicate that water molecules in the deeper formations are derived from primary concentrated seawater isotope enrichment by exchange with carbonates and perhaps gypsum cannot be discounted isotope values indicate water in the upper devonian formations is a mixture of seawater brine diluted with meteoric derived water dilution has predominantly occurred in basin margins two scenarios are presented for the origin of the brines in the devonian formations 1 they originated when the devonian sediments and evaporites were first deposited or 2 they are residual brine liberated from the deeper devonian and possibly silurian salt deposits

the geomorphological and geological importance of palaeosurfaces this special publication is a collection of papers which identifies describes and interprets the occurrence of palaeosurfaces in the geological record the concept of a palaeo surface is one which is generally understood across the geomorphological and geological sciences but according to discipline and application often differs in the emphasis and detail of its interpretation in order to encompass the widest range of contributions and views upon the subject of palaeosurfaces a broad remit was deliberately adopted during the preparation of this volume cations of ancient palaeosurfaces the research areas represented are geographically widespread and include examples from australia africa south america india and europe

runoff to boreal lakes linked to land cover watershed morphology and permafrost thaw a 9 year isotope mass balance assessment stable isotopes of oxygen and hydrogen were measured in water samples collected annually from a representative suite of 50 lakes in northeastern alberta over a 9 year period and are interpreted using a steady state isotope mass balance model to determine water yield and runoff ratios for the lake watersheds and residence time of the lakes this isotopic perspective on hydrology of the region provides new insight into the role of land cover watershed morphometry climatic drivers and permafrost thaw on lakes bog cover permafrost and presence of thaw features in bogs are found to be the dominant hydrologic drivers although morphometric properties such as elevation lake area and drainage basin area are also influential in addition to quantifying the hydrologic fluxes the analysis establishes contrasting conditions in more southerly lakes located in the stony mountains and west of fort mcmurray as compared with more northerly sites in the birch mountains caribou mountains and northeast of fort mcmurray mainly because of contributions from thawing permafrost at the northerly sites distinct hydrologic conditions are also noted for shield systems north of lake athabasca where bogs and permafrost are absent while permafrost thaw is not directly labelled by oxygen and hydrogen isotope composition isotope mass balance calculations suggest that contributions of up to several hundred millimetres per year are occurring in 14 of the 50 lake watersheds under study several of these lakes have water yields in excess of precipitation in some years and regional groups of lakes display significant correlations between water yield and percentage of bogs that have collapsed copyright 2015 john wiley sons ltd

using 81kr and noble gases to characterize and date groundwater and brines in the baltic artesian basin on the one million year timescale abstract analyses for 81 kr and noble gases on groundwater from the deepest aquifer system of the baltic artesian basin bab were performed to determine groundwater ages and uncover the flow dynamics of the system on a timescale of several hundred thousand years we find that the system is controlled by mixing of three distinct water masses interglacial or recent meteoric water 18 o 10 4 with a poorly evolved chemical and noble gas signature glacial meltwater 18 o 18 with elevated noble gas concentrations and an old high salinity brine component 18 o 4 5 90 g cl l with strongly depleted atmospheric noble gas concentrations the 81 kr measurements are interpreted within this mixing framework to estimate the age of the end members deconvoluted 81 kr ages range from 300 ka to 1 3 ma for interglacial or recent meteoric water and glacial meltwater for the brine component ages exceed the dating range of the atta 3 instrument of 1 3 ma the radiogenic noble gas components 4 he and 40 ar are less conclusive but also support an age of 1 ma for the brine based on the chemical and noble gas concentrations and the dating results we conclude that the brine originates from evaporated seawater that has been modified by later water rock interaction as the obtained tracer ages cover several glacial cycles we discuss the impact of the glacial cycles on flow patterns in the studied aquifer system

evolution of groundwater systems at the european coastline an overview is given of the status and origin of fresh and saline groundwaters in the sedimentary aquifers at or near the present european coastline results are presented as six regional maps summarizing as far as possible the conditions likely to have existed at the end of the pleistocene after the impact of glaciation when groundwaters might be expected to have reached their maximum offshore evolution prior to the encroachment of sea water during the holocene marine transgression in the eastern baltic the groundwater evolution was different to other european regions in that freshwater heads were higher than the present day promoting recharge during much of the late pleistocene near the north sea coasts there is generally evidence of freshwater movement to depths of 100 150 m but the absence of deeper freshwater palaeowater storage may relate to the low hydraulic gradients in the north sea basin in the southeastern part of the north sea brackish palaeowater is found between tertiary marine sediments c 300 m below the island of rcmo l 0 km off the danish west coast freshwater of pleistocene and holocene ages is found in aquifers at the english channel coast in several areas to depths in excess of 300 m offshore flow in the late pleistocene took place towards the central palaeovalley and some of this groundwater may be preserved off the present coastline in the two atlantic coastal areas of france and portugal spain a contrast exists due to the proximity of the continental margin and different hydraulic gradients in portugal freshwaters are found at the coastline and probably offshore that contain evidence of recharge during the lowered sea levels in most of the southwestern atlantic coast of spain fresh recent groundwater discharges along and beyond the coastline while in the old estuary of the guadalquivir river saline holocene water still encroaches the sediments on the mediterranean coast of france and spain some salinity encroachment took place during sea level rise in most of the spanish aquifers fresh recent groundwater has substituted for palaeowater except for the low lying areas ebro delta inca sa pobla plain where brackish holocene water is still present

quaternary uplift vs tectonic loading a case study from the lucanian apennine southern italy abstract uplift rates have been calculated for a large sector of the lucanian apennine axial zone of the southern apennines italy using both geomorphological observations elevation values ages and arrangement of depositional and erosional landsurfaces and other morpho tectonic indicators and stratigraphical and structural data sea level related facies fault kinematics and offset estimations these data have been compared with those derived from clay mineralogy of mesozoic pelagic successions lagonegro units outcropping in the same sector of the chain which gave information on tectonic loading the values of the quaternary uplift rates of the southern apennines axial zone vary from a minimum of 0 2 mm yr to a maximum of about 1 2 mm yr intermediate values 0 5 0 7 mm yr have been calculated for the other studied areas using geomorphological features and late pliocene to pleistocene successions involved in the genesis of erosional and depositional landsurfaces the same rates 0 6 mm yr have been obtained for a large time span about 2 ma in the melandro basin and adjacent maddalena mts therefore during the last 2 ma the total uplift amount of the axial zone of the lucanian apennine is about 1 2 1 3 km with local peaks of 1 5 km on the other hand the mesozoic pelagic units experienced a tectonic loading of 4 5 km as estimated by means of illite crystallinity in the range 0 6 1 1 2 percentage of illitic layers in illite smectite mixed layers 60 90 and white mica polytypes in the range of 10 35 the quaternary uplift and the related erosion rates of the southern apennines are unquestionably due to strike slip faulting and above all due to extensional tectonics coupled with thermal isostatic regional raising the gap of several kilometres derived from the comparison between uplift rates and tectonic loading values may be explained only by different exhumation modalities starting from late miocene time

late quaternary faulting within the southern apennines seismic belt new data from mt marzano area southern italy abstract an integrated geomorphological and geophysical investigation was performed in order to reconstruct the pliocene quaternary geomorphologic evolution and recent tectonics of mt marzano massif southern apennines italy the study area belongs to a region of high seismic energy release the last event being the strong ms 6 9 1980 irpinia earthquake most of the main faults of the area ceased their activity before development of the late pliocene age palaeosurfaces widely spread over the massif beginning in the lower part of the middle pleistocene strong extensional tectonics took place in the southern portion of the massif wnw trending faults created the buccino and s gregorio magno depressions which underwent subsidence until the holocene according to abundant morphostructural evidence during the late quaternary the n150 trending mt valva mt carpineta fault and the n110 100 trending mt ogna fault previously sealed by pliocene palaeosurfaces also were re activated morphostructural data were integrated with a high resolution seismic survey across the piano di pecore basin which is dammed by a fault that slipped 70 cm during the 1980 earthquake this fault produced no more than 50 60 m of throw during quaternary times most probably starting from 100 to 150 kyr bp

glacier meltwater flow paths and storage in a geomorphologically complex glacial foreland the case of the tapado glacier dry andes of chile 30 s summary the tapado catchment is located in the upper elqui river basin 4000 5550 m in northern chile it comprises the tapado glacial complex which is an assemblage of the tapado glacier and the glacial foreland debris covered glacier rock glacier and moraines although the hydrological functioning of this catchment is poorly known it is assumed to actively supply water to the lower semi arid areas of the elqui river basin to improve our knowledge of the interactions and water transfers between the cryospheric compartment glacier debris covered glacier and rock glacier and the hydrological compartment aquifers streams the results of monitoring of meteorological conditions as well as discharge conductivity and temperature of streams and springs located in the tapado catchment were analyzed the hydrological results are compared to results inferred from a ground penetrating radar gpr survey of the underground structure of the glacial foreland water production from the tapado glacier was shown to be highly correlated with daily and monthly weather conditions particularly solar radiation and temperature the resulting daily and monthly streamflow cycles were buffered by the glacial foreland where underground transfers took place through complex flow paths however the development of a thermokarst drainage network in a portion of the glacial foreland enabled rapid concentrated water transfers that reduced the buffer effect the glacial foreland was shown to act as a reservoir storing water during high melt periods and supplying water to downstream compartments during low melt periods gpr observations revealed the heterogeneity of the internal structure of the glacial foreland which is composed of a mixture of ice and rock debris mixture with variable spatial ice content including massive ice lenses this heterogeneity may explain the abovementioned hydrological behaviors finally calculation of a partial hydrological budget confirmed the importance of the tapado catchment in supplying water to lower areas of the elqui river basin water production from and transfer through cryospheric compartments and its subsequent interactions with hydrological compartments are key processes driving the summer water supply from the tapado catchment

analysis and characterization of the vertical accuracy of digital elevation models from the shuttle radar topography mission 1 the first near global high resolution digital elevation model dem of the earth has recently been released following the successful shuttle radar topography mission srtm of 2000 this data set will have applications in a wide range of fields and will be especially valuable in the earth sciences prior to widespread dissemination and use it is important to acquire knowledge regarding the accuracy characteristics in this work a comprehensive analysis of the vertical errors present in the data set and the assessment of their effects on different hydrogeomorphic products is performed in particular the work consisted of 1 measuring the vertical accuracy of the data set in two areas with different topographic characteristics 2 characterizing the error structure by comparing elevation residuals with terrain attributes 3 assessing a wavelet based filter for removing speckle and 4 assessing the effects of vertical errors on hydrogeomorphic products and on slope stability modeling the results indicate that in the two sites relief has a strong effect on the vertical accuracy of the srtm dem in the high relief terrain large errors and data voids are frequent and their location is strongly influenced by topography while in the low to medium relief site errors are smaller although the hilly terrain still produces an effect on the sign of the errors speckling generates deviations in the drainage network in one of the investigated areas but the application of a wavelet filter proved to be an effective tool for removing vertical noise although further fine tuning is necessary vertical errors cause differences in automatically extracted hydrogeomorphic products that range between 4 and 1090

cenozoic uplift of nuussuaq and disko west greenland elevated erosion surfaces as uplift markers of a passive margin remnants of a high plateau have been identified on nuussuaq and disko central west greenland we interpret the plateau as an erosion surface the summit erosion surface formed mainly by a fluvial

erosion thresholds and land surface morphology we propose a graphical technique to analyze the entirety of landforms in a catchment to define quantitatively the spatial variation in the dominance of different erosion processes high resolution digital elevation data of a 1 2 km2 hilly area where the channel network had been mapped in the field were used in the digital terrain model topog to test threshold theories for erosion the land surface was divided into 20 m2 elements whose shapes were then classified as convergent planar or divergent the entire landscape plotted on a graph of area per unit contour length against surface gradient shows each planform plotting as a separate field a simple steady state hydrologic model was used to predict zones of saturation and areas of high pore pressure to mimic the extreme hydrologic events responsible for erosive instability of the land surface the field observation that saturation overland flow is rare outside convergent zones provided a significant constraint on the hydrologic parameter in the model this model was used in threshold theories to predict areas of slope instability and areas subject to erosion by saturation overland flow both of which can contribute to channel initiation the proportion of convergent elements predicted to exceed the threshold varies greatly with relatively small changes in surface resistance demonstrating a high sensitivity to land use such as cattle grazing overall the landscape can be divided using erosion threshold lines into areas prone to channel instability due to runoff and stable areas where diffusive transport predominates

deformation of the 125 ka marine terrace in italy tectonic implications in peninsular italy marine terraces and shorelines created during oxygenisotope substage 5e known historically as the tyrrhenian highstand provide a reliable and homogeneous datum of vertical motions during the past 125 000 years published accounts of 121 locations on the tyrrhenian inner edge were reinterpreted and used to calculate both local and regional uplift rates the data show arching of southern italy between the tyrrhenian and the adriatic coasts and of the calabrian arc between the sangineto and the longi taormina tectonic lineaments at rates of up to 1 2 mm yr for the past 125 ka they also suggest that the present configuration of the southern apennines is the product of post early pleistocene regional uplift superimposed on tortonian to early pleistocene thrusting uplift patterns are characterised by different wavelength in different geodynamic settings suggesting a close link with the depth of the causative tectonic sources

glacial hydrology and erosion patterns a mechanism for carving glacial valleys article i nfo article history most glacial erosion models assume that erosion rates are proportional to ice sliding velocity while recent studies have shown that water plays a major role in modulating sliding velocities the impact it might have on erosion rates is still unclear here we incorporate subglacial hydrology into a glacial erosion model that is based on a sliding rule our results explicitly highlight that adding subglacial hydrology has profound impacts on the temporal and spatial patterns of glacial erosion first it suggests that erosion might mainly occur during melting seasons when subglacial water pressure is large and effective pressure is low i e before the channels fully develop and reduce the water pressure at the ice bedrock interface which promotes sliding and erosion second the distribution of erosion is bimodal with a peak at the equilibrium line altitude and as we demonstrate enhanced erosion at much lower altitudes within the ablation area where water due to melting abounds this has important implications because it explains why glacial erosion can simultaneously

revision of fontes garnier s model for the initial 14c content of dissolved inorganic carbon used in groundwater dating abstract the widely applied model for groundwater dating using 14c proposed by fontes and garnier fg or 2 using different fractionation factors if the exchange process is dominated by soil co2 gas as opposed to solid carbonate mineral typically calcite an analysis of the fg however 14c0 will be slightly underestimated finally in carbonate systems undergoing complex geochemical reactions such as oxidation of organic carbon radiocarbon ages are best estimated by inverse geochemical modeling techniques

the interglacial glacial cycle and geochemical evolution of canadian and fennoscandian shield groundwaters abstract results from cryogenic column experiments are compared with the geochemical data collected in the canadian and fennoscandian shields over the past 25 years to investigate the relative influence of the glacial interglacial cycle specifically the impact of continental glaciers permafrost and methane hydrate on the evolution of groundwater from crystalline shield environments several different geochemical indicators of freezing processes either glacial or permafrost related were utilized comparisons of na cl and br cl ratios 18 o and 2 h values and 18 o values and cl concentration during freezing fluids with different dominant cations follow distinctly different linear trends when na cl and br cl ratios are compared significantly none of the freezing trends follows the trend hypothesized by herut et al 1990 for the evolution of seawater chemistry during freezing intrusion of glacial meltwater and in situ freezing i e permafrost formation result in a similar end member when comparing 18 o values and cl concentration the geochemical influence of a freezing process on fresh brackish and some saline fluids was identified at some but not all canadian shield sites regardless of site location with respect to modern day permafrost appreciably physical and geochemical data do not support the formation of brines through any freezing process in the canadian and fennoscandian shields as hypothesized by starinsky and katz 2003 rather on all diagnostic freezing plots brines are an end member indicating a different evolutionary pathway significant depletions in 18 o with respect to modern precipitation an indication of either glacial meltwater or a freezing process were identified at depths of up to 1 km at some sites in the canadian shield and to shallower depths in the fennoscandian shield the potential of this fluid to reach such depths could be attributable to artificial gradients and mixing glacial recharge permafrost or paleo permafrost formation or methane hydrate or paleo methane hydrate formation at most locations it was not possible to distinguish between the different scenarios using the current geochemical database

erosional landsurfaces of the campano lucano apennines s italy genesis evolution and tectonic implications abstract within the campano lucano apennines small but widespread relics of gentle erosional landsurfaces gels occur that are elevated several hundred metres above the present valley floors on the basis of our observations the old idea that all these relict landforms can be traced back to a single phase of quasi planation that affected the entire belt after thrust stacking and before a phase of final uplift must be rejected new field evidence and chronological constraints support the conclusion that the gel relics belong to various uncompleted cycles of erosion that occurred just during the construction of the chain i e late miocene to early pleistocene as many recent geological studies have pointed out the southern apennines chain is an arc shaped accretionary wedge that migrated as a thrusting system towards its retreating foreland by means of addition of thrust units to the front and loss of rifted portions at the rear tyrrhenian back arc basin also the spatial distribution of the various generations of gels their ages and their relations to the main structures and syn orogenic formations of the belt seem to agree with this geodynamic scenario here we propose a first approximation conceptual model that considers each generation of campano lucano apennines gels as largely formed when the thrust units on which they rest were located at low elevation near the coastline of the foredeep basin i e shortly after the entrance of those thrust units into the tectonic wedge then each gel as a matter of fact the compartment on which it rested was taken towards more and more internal parts of the wedge as frontal accretion continued owing to this relative migration the fate of each gel carrying compartment was to reach the part of the belt that was affected by extensional block faulting i e the tyrrhenian side of the chain each gel eventually reaching this domain was tectonically fragmented deeply cut by waves of fluvial dissection proceeding from the steep tectonic coast toward the ne and finally also rifted under the tyrrhenian sea other causes of gels fragmentation and dissection were probably the breaching of the chain s outer flank by out of sequence thrust and the up arching of the roof thrust system caused by the formation of deep anticlinal stacks on the contrary when forward propagation of thrusts continued for long periods the gels being carried toward the inner zone of the wedge could not have experienced deep dissection because the increase of their elevation a s l was compensated by their increasing distance from the foredeep coastline maintenance of low gradient along the river valleys thanks to a very low critical taper

verification of the vertical error in c band srtm dem using icesat and landsat 7 otter tail county mn the shuttle radar topography mission srtm provided scientists with digital elevation data on a nearly global scale and with highly consistent accuracy this paper compares elevation values of the c band srtm 30 m digital elevation model dem with pointwise elevations from the ice cloud and land elevation satellite icesat laser altimetry for otter tail county minnesota the accuracy of srtm dem is measured as a function of land covers and geomorphologic characteristics the typical mean vertical difference between the srtm dem and icesat elevations in this paper was determined in each classified land use type and is approximately 1 5 m over bare ground with the srtm measuring lower elevations significant changes in the srtm dem uncertainties have been identified over different surface types classified from landsat 7 imagery e g bare ground urban and forested areas based on this result the difference of the srtm 30 m dem and icesat elevations has been removed from the dem and made available for improved hydrological applications

using stable isotopes to characterize the conditions of groundwater formation on the eastern slope of the baltic shield nw russia abstract repeated continental glaciations and marine transgressions had a strong influence on the geochemical evolution of groundwater systems of the eastern slope of the baltic shield arkhangelsk region russia the spectrum from modern fresh waters to very old brines is distributed from the surface to a depth of 1 km in quaternary and vendian ediacaran sediments the purpose of this study was to i assess the isotopic composition of various types of groundwater ii assess the degree of participation of glacial melt and meteoric waters in the processes of dilution of seawater and brines according to isotope geochemical data and iii employ the use of stable isotopes to clarify previously performed groundwater dating it has been established that the salty water in the upper part of the vendian aquifer near the modern sea coast has maximum enrichment by heavy isotopes 18o 7 7 and 2h 98 9 on average it is a mixture of 19 51 glacial meltwater and 49 81 seawater the age of the marine component is 115 130 ka and the age of the glacial water is similar to that of the middle pleistocene the relict brackish water in the middle part of the vendian aquifer has the most depleted isotope composition 18o 14 1 and 2h 106 7 on average it is a mixture of 3 brine 8 19 glacial and 78 89 interglacial water and was formed in the range of 35 3 22 3 ka late pleistocene the maximum brine content 10 17 is characteristic of salt water in the lower part of the vendian aquifer the isotope composition of the fresh water is close to the weighted annual composition of modern precipitations 18o 13 2 and 2h 98 9 fresh water is a mixture of about 2 seawater up to 16 glacial water and 84 100 holocene water the age of this water is in the range from the present day to 11 8 1 6 ka the maximum depth of penetration of melt glacial waters of the middle pleistocene is assumed to be 600 m

the recharge of glacial meltwater and its influence on the geochemical evolution of groundwater in the ordovician cambrian aquifer system northern part of the baltic artesian basin abstract the geochemical evolution of groundwater in the ordovician cambrian aquifer system in the northern part of the baltic artesian basin bab illustrates how continental glaciations have influenced groundwater systems in proglacial areas the aquifer system contains water that has originated from various end members recent meteoric water glacial meltwater and relict na cl brine the saline formation water that occupied the aquifer system prior to the glacial meltwater intrusion has been diluted by meltwaters of advancing retreating ice sheets the diversity in the origin of groundwater in the aquifer system is illustrated by a wide variety in 18 o values that range from 11 to 22 5 these values are mostly depleted with respect to values found in modern precipitation in the area the chemical and isotopic composition of groundwater has been influenced by mixing between waters originating from different end members in addition the freshening of a previously saline water aquifer due to glacial meltwater intrusion has initiated various types of water rock interaction e g ion exchange carbonate mineral dissolution

pleistocene hydrology of north america the role of ice sheets in reorganizing groundwater flow systems 1 while the geomorphic consequences of pleistocene megafloods have been known for some time it has been only in the past 2 decades that hydrogeologists and glaciologists alike have begun to appreciate the important impact that ice sheet aquifer interactions have had in controlling subsurface flow patterns recharge rates and the distribution of fresh water in confined aquifer systems across north america in this paper we document the numerous lines of geochemical isotopic and geomechanical evidence of ice sheet hydrogeology across north america we also review the mechanical thermal and hydrologic processes that control subsurface fluid migration beneath ice sheets finite element models of subsurface fluid flow permafrost formation and ice sheet loading are presented to investigate the coupled nature of transport processes during glaciation deglaciation these indicate that recharge rates as high as 10 times modern values occurred as the laurentide ice sheet overran the margins of sedimentary basins the effects of ice sheet loading and permafrost formation result in complex transient flow patterns within aquifers and confining units alike using geochemical and environmental isotopic data we estimate that the volume of glacial meltwater emplaced at the margins of sedimentary basins overrun by the laurentide ice sheet totals about 3 7 104 km3 which is about 0 2 of the volume of the laurentide ice sheet subglacial infiltration estimates based on continental scale hydrologic models are even higher 5 10 of meltwater generated these studies in sum call into question the widely held notion that groundwater flow patterns within confined aquifer systems are controlled primarily by the water table configuration during the pleistocene rather groundwater flow patterns were likely much more complex and transient in nature than has previously been thought because pleistocene recharge rates are believed to be highly variable these studies have profound implications for water resource managers charged with determining sustainable pumping rates from confined aquifers that host ice sheet meltwater

mechanisms of subglacial groundwater recharge as derived from noble gas 14c and stable isotopic data abstract noble gas stable isotope and 14c data from samples collected along groundwater flow path within a confined paleozoic aquifer in northeastern wisconsin usa are used to deduce the effect of the laurentide ice sheet lis on the underlying groundwater and its recharge dynamics during the last glacial maximum the investigated area was near the center of the green bay lobe of the lis 14c ages that extend to 26 k a and low 18o derived temperatures during the time that the lis was present indicate that aquifer recharge continued when ice covered the area 18o values as low as 17 5 and 2h values as low as 127 7 indicate that a significant portion of aquifer recharge was derived from glacial meltwater that maintained its glacial isotopic signature during melting and subsequent recharge noble gas temperatures that remain above freezing at a constant 3 c unusually high excess air ne values and noble gas fractionation patterns indicate that recharge occurred across a very dynamic water table located within the ice sheet this englacial hydrologic system experienced recharge heads of as much as 7 8 m evidence for direct recharge of basal meltwater into the aquifer is not seen to the authors knowledge this is the first time that noble gas and isotope tracers have been used to deduce the provenance of aquifer water beneath continental ice sheets

structure of the subduction transition region from seismic array data in southern peru data from three seismic arrays installed in southern peru were analysed using receiver functions from p pp and pkp wave phases in order to image the subducted nazca slab the arrays cover the transition region from flat slab subduction in central peru to normal subduction with an angle of about 30 further south a previous study used data from the first array in the normal subduction region to image the moho depth and slab and showed the existence of a mid crustal structure at 40 km depth that is suggested to be a possible underthrusting of the brazilian shield here we discuss new observations from the other two arrays that span the transition between the two subduction regimes and the flat subduction region the results provide an image of the flattened slab from the coast to approximately 300 km inland and also across the transition region from flat to 30 subduction which appears to be a bend rather than a tear in the slab in the flat slab region the slab is well defined near the coast and flattens out at 100 km depth beneath the altiplano the slab appears to start flattening some 400 km in advance of the subduction of the nazca ridge and the flattening is maintained for 1300 km after its passage the moho begins at a depth of around 30 km near the coast and has a maximum depth of 75 km beneath the altiplano consistent with the results of the other arrays both arrays also show a positive impedance mid crustal structure at 40 km depth which if explainable by underthrusting of the brazilian shield would add further support to the observations from the normal subduction region and show the northward and westward extent of the signal the underthrusting hypothesis would explain the missing crust from the shortening budget needed to support the altiplano the vp vs ratios for both arrays exhibit average values between 1 73 and 1 75 indicating a lesser likelihood that there is a high degree of partial melting or magma bodies at depth in this region the receiver function results provide new imaging of the flat slab and transition from normal to flat slab subduction which allows for comparison of different subduction regimes