a positive altitude gradient of isotopes in the precipitation over the tianshan mountains effects of moisture recycling and sub cloud evaporation abstract a negative stable isotope altitude gradient is commonly observed on the windward side of a mountain however after the precipitation passes over a mountain range to the leeward side the altitude effect becomes ambiguous as a result of an orographic rain shadow in addition to other complex processes such as sub cloud evaporation and additional moisture mixing in this study we found a positive precipitation 18 o altitude gradient with a value of 0 12 100 m in the urumqi river catchments on the leeward side of the tianshan mountains through an analysis of water isotopes sampled in this region processes including both sub cloud evaporation and moisture recycling were found to be responsible for the positive gradient a simple model was built to analyze the observations quantitatively we defined the difference of the recycled evaporated fraction as the recycled evaporated fraction at the lower station minus the fraction at the higher station the model showed that the 18 o altitude gradient rises by 0 28 100 m with the difference of the recycled fraction increasing by 1 100 m and declining by 0 15 100 m with the difference of the evaporated fraction increasing by 1 100 m the effect of moisture recycling is more significant than that of sub cloud evaporation on the leeward side of the tianshan mountains therefore the precipitation in the tianshan mountains has a positive 18 o altitude gradient the model also explains the distribution of water isotope data points in the 2 h 18 o figure of northwest china while the data points of the mountainous water isotopes are located above the local meteoric water line lmwl because of moisture recycling most data points of basin water isotopes are located below the lmwl because of evaporation accordingly we concluded that the stable isotope altitude gradient on the leeward side of a mountain is very sensitive to local atmospheric processes an inference that should be taken into consideration while quantifying the paleo altitude of orogeny and groundwater recharge area using stable water isotopes

detection of potential fields source boundaries by enhanced horizontal derivative method a high resolution method to image the horizontal boundaries of gravity and magnetic sources is presented the enhanced horizontal derivative ehd method the ehd is formed by taking the horizontal derivative of a sum of vertical derivatives of increasing order the location of ehd maxima is used to outline the source boundaries while for gravity anomalies the method can be applied immediately magnetic anomalies should be previously reduced to the pole we found that working on reduced to the pole magnetic anomalies leads to better results than those obtainable by working on magnetic anomalies in dipolar form even when the magnetization direction parameters are not well estimated this is confirmed also for other popular methods used to estimate the horizontal location of potential fields source boundaries the ehd method is highly flexible and different conditions of signal to noise ratios and depths to source can be treated by an appropriate selection of the terms of the summation a strategy to perform high order vertical derivatives is also suggested this involves both frequency and space domain transformations and gives more stable results than the usual fourier method the high resolution of the ehd method is demonstrated on a number of synthetic gravity and magnetic fields due to isolated as well as to interfering deep seated prismatic sources the resolving power of this method was tested also by comparing the results with those obtained by another high resolution method based on the analytic signal the success of the ehd method in the definition of the source boundary is due to the fact that it conveys efficiently all the different boundary information contained in any single term of the sum application to a magnetic data set of a volcanic area in southern italy helped to define the probable boundaries of a calderic collapse marked by a number of magmatic intrusions previous interpretations of gravity and magnetic fields suggested a subcircular shape for this caldera the boundaries of which are imaged with better detail using the ehd method

hydrological changes in western central asia kyrgyzstan during the holocene as inferred from a palaeolimnological study in lake son kul abstract the hydrology of western central asia is highly sensitive to climatic perturbations in order to understand its long term variability and to infer linkages between precipitation and atmospheric and oceanic systems we conducted a thorough sedimentary and geochemical study on a composite core retrieved in lake son kul central kyrgyzstan a multi proxy approach was conducted on lake sediments based on grain size analyses magnetic susceptibility total organic carbon toc total nitrogen tn and carbon and oxygen isotope analyses on bulk and biogenic materials ostracoda and molluscs shells at a resolution equivalent to ca 40 years aiming to characterise the sequence of palaeolimnological changes in son kul as indicated by 18 o record of bulk carbonates mainly consisting of aragonite the holocene hydrological balance was negative during most of time suggesting an excess of evaporation e over precipitation p limnological conditions fluctuated rapidly before 5000 cal yr bp indicating significant changes in regional hydrology and climate in particular the long term negative hydrological balance was impeded by several short stages with marked increase of precipitation lasting several decades to a few centuries e g 8300 8200 6900 6700 6300 6100 5500 5400 5300 5200 and 3100 3000 cal yr bp precipitation changes as inferred from 18 o data are also documented by increased minerogenic detritus and higher toc we propose that the seasonal pattern of precipitation varied transiently in western central asia during the holocene although evaporation changes may also account for the rapid changes observed in 18 o data when the annual water balance was less critical p e the excess of water might be ascribed to increased precipitation during cold seasons mainly because winter precipitation has more negative 18 o than its summer equivalent conversely when the annual water balance is negative p e the moisture was mainly delivered during the warm season as between 5000 and 2000 cal yr bp our results thus imply that moisture sources could have changed as well during the holocene moisture was delivered as today mainly during summer from the extended caspian aral basin and eastern mediterranean although arctic and even north atlantic seas might be important moisture sources when seasonal precipitation was dominated by winter precipitation we hypothesise that warming arctic and north atlantic seas were important for the north hemisphere circulation during the cold season

stable isotope time series and precipitation origin from firn core and snow samples altai glaciers siberia in the summers of 2001 and 2002 glacio climatological research was performed at 4110 4120ma s l on the belukha snow firn plateau siberian altai hundreds of samples from snow pits and a 21m snow firn core were collected to establish the annual seasonal monthly depth accumulation scale based on stable isotope records stratigraphic analyses and meteorological and synoptic data the fluctuations of water stable isotope records show well preserved seasonal variations the d 18 o and dd relationships in precipitation snow pits and the snow firn core have the same slope to the covariance as that of the global meteoric water line the origins of precipitation nourishing the belukha plateau were determined based on clustering analysis of d 18 o and d excess records and examination of synoptic atmospheric patterns calibration and validation of the developed clusters occurred at event and monthly timescales with about 15 uncertainty two distinct moisture sources were shown oceanic sources with d excess 12 two thirds of the annual accumulation was from oceanic precipitation of which more than half had isotopic ratios corresponding to moisture evaporated over the atlantic ocean precipitation from the arctic pacific ocean had the lowest deuterium excess contributing one tenth to annual accumulation

automatic lineament extraction from potential field images using the radon transform and gradient calculation linear anomalies are critical in the interpretation of gravity and magnetic data visual identification of lineaments is usually done by experienced interpreters and identification results then have to undergo a digitization or import procedure the traditional identification method has unavoidable subjectivity and inefficiency to overcome these limitations we fuse the radon transform rt with gradient calculation to process gravity or magnetic data and to realize automatic detection and extraction of lineaments as part of the detection procedure we define the rt based mean gradient mg effective mean gradient emg and residual mean gradient rmg in order to highlight long linear segments or to enhance short linear ones in the transform domain the gradient forms are applied self adaptively and self selectively to gravity or magnetic images according to specific conditions gradient directions are also taken into account in the transformation procedure to emphasize the characteristics of linear anomalies to extract the position and length of the detected lineaments from the transform domain a constraint inverse searching method cism is given and used to locate the starting and end points of the lineaments the method can deal with the condition that there is at least one linear section in a specific direction or that separate linear sections may belong to one lineament through tests with synthetic images and with real data from the haijiao upheaval area in the east china sea basin the detection and extraction methods are shown to be more effective and robust than the conventional rt applications the results from the real data roughly coincide with major geologic faults that are visually identified these results show that the methods constitute a useful tool to aid fault interpretation

kinematics of the inntal shear zone sub tauern ramp fault system and the interpretation of the transalp seismic section eastern alps austria abstract a new interpretation of the inntal tauern sector of the transalp seismic section is presented one of the most prominent contrasts in reflectivity in the transalp seismic section is the contact between the bajuvaric unit in the footwall and the overlying tirolic unit and its basement across a moderately south dipping interface we trace this contact from the surface at the southern margin of the inn valley to a depth of 5 km there the contact is deformed or cut by the tauern window northern margin we define the contact between bajuvaric and tirolic units as brixlegg thrust which is older than miocene tauern window exhumation and has a paleogene age the sub tauern ramp connects with the inntal fault system at the surface and roots below the tauern window oblique thrust movements across this fault system in the miocene caused exhumation of the hanging wall where the fault has a ramp geometry which is in the area of the transalp cross section and west of it east of the transalp cross section the fault system merges with alpine basal thrust which is a flat no miocene exhumation occurred above the flat

glacial regime of the highest tien shan mountain pobeda khan tengry massif major processes controlling the existence of a large sub continental glacier system were identified on the basis of glaciological meteorological and isotopic analyses using expeditionary and long term data observations were made on the southern inylchek glacier located in the pobeda khan tengry massif the largest sub continental glacier system on the northern periphery of central asia more than 1200 glaciers with a total area of about 4320 km comprise the massif melt is for the most part caused by radiation and is most intensive during periods of anticyclonic weather with fohn development the proportion of solar radiation input in relation to heat balance is more than 90 evaporation and condensation are negligible during most times and comprise 7 of heat expenditure accumulation was associated with cold cyclonic weather four ice formation zones were identified the upper boundary of liquid runoffis at 5200 m and the recrystallization zone is above 5900 m the calculated net glacier mass is negative 318 kg m 2 a 1 and indicates the degradation of modern pobeda khan tengry glaciers

edge enhancement of potential field data using normalized statistics edge enhancement in potential field data helps geologic interpretation there are many methods for enhancing edges most of which are high pass filters based on the horizontal or vertical derivatives of the field normalized standard deviation nstd a new edge detection filter is based on ratios of the windowed standard deviation of derivatives of the field nstd is demonstrated using aeromagnetic data from australia and gravity data from south africa compared with other filters the nstd filter produces more detailed results

orogenic structure of the eastern alps europe from transalp deep seismic reflection profiling abstract the transalp group comprising of partner institutions from italy austria and germany acquired data on a 340 km long deep seismic reflection line crossing the eastern alps between munich and venice although the field work was split into four campaigns between fall 1998 and summer 2001 the project gathered for the first time a continuous profile across the alps using consistent field acquisition and data processing parameters these sections span the orogen itself at its broadest width as well as the editor fred davey and the two adjacent basins vibroseis and explosion data complementary in their depth penetration and resolution characteristics were obtained along with wide angle and teleseismic data the profile shows a bi vergent asymmetric structure of the crust beneath the alpine axis which reaches a maximum thickness of 55 km and 80 100 km long transcrustal ramps the southward dipping sub tauern ramp and the northward dipping sub dolomites ramp strongly reflective patterns of these ramps can be traced towards the north to the inn valley and towards the south to the valsugana thrust belt both of which show enhanced seismicity in the brittle upper crust the seismic sections do not reveal any direct evidence for the presence of the periadriatic fault system the presumed equivalent to the insubric line in the western alps according to our new evolutionary model the sub tauern ramp is linked at depth with remnants of the subducted penninic ocean the crocodile type model describes an upper lower crustal decoupling and wedging of both the european and the adriatic african continents

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

linear feature analysis for aeromagnetic data this paper presents a new approach to detecting and two approaches to displaying lineaments associated with high angle magnetic contacts based on analysis of the curvature of the total horizontal gradient of the total magnetic field reduced to the pole the first display is a contour or color plot of minus the principal curvature of largest absolute value the second is a point plot of the local maxima of minus the largest principal curvature in regions where this curvature is negative the paper also develops a depth estimation technique for magnetic contacts based on the ratio of the curvature of the total gradient to the total gradient itself tests on synthetic data yield excellent results in detecting and delineating magnetic contact edges and reasonable performance in producing depth estimates for the magnetic contacts results obtained using aeromagnetic data from the finger lakes region of new york state show good correlation with known structural features

shear wave splitting in the eastern alps observed at the transalp network data from the temporary transalp seismic network were analysed to investigate the seismic anisotropy in the upper mantle beneath the eastern alps we operated mostly short period and some broadband stations in a dense linear array which transects the eastern alps at 12 e longitude recorded sks and skks phases with different backazimuths were used simultaneously to calculate the splitting parameters of delay time and fast axis direction for each seismic station while we found variations in the delay times between 0 8 and 2 0 s the determined fast axis directions prove to be rather consistent along the profile 60 70 n they coincide well with the trend of the eastern alps thus suggesting orogen parallel flow in the upper mantle our findings support the earlier proposed idea that the adriatic indenter which was forced northwards into the european plate during the late stage of the alpine orogeny triggered an escape movement to the less constrained pannonian basin to the east

kinematics of austro alpine cover nappes changing translation path due to transpression upper and middle austro alpine nappes of the eastern alps the structural uppermost subunits of the alps suffered two major superposed deformations d1 d2 during the eo alpine cretaceous orogeny d1 is characterized by nw to w directed thrusting and nappe internal rock flow d2 by large scale folding and imbrication toward the north and northeast structures strain metamorphic history microfabrics and stretching trajectories indicate that the superposition of d2 over d1 structures can be interpreted as a progressive deformation it is concluded that the emplacement of the nappes follows a curved translation path a model which emphasizes non coaxial deformation structures explains the detachment of the nappes the configuration of the separating thrust planes and the distribution of intense deformation zones the overall kinematic history of the austro alpine nappes fits a model in which strike slip shearing horizontal shortening and vertical lengthening act together continuously over a finite deformation zone transpressional model this model emphasizing a gradually changing strain regime eliminates the space problems encountered in models which consider simple south over north imbrication during the alpine orogeny the study stresses two interpretations 1 1 stretching lineations indicate nappe transport directions 2 2 transpression may be a common feature of orogenic belts

the isotopic composition of meteoric water along altitudinal transects in the tian shan of central asia abstract the tian shan in central asia are a unique mountain range in that they are in the world s most continental location seasonal precipitation in the northern tian shan is segregated into distinct elevation bands where high elevations receive precipitation primarily during summer and low elevations to the north receive precipitation primarily during the late winter and spring in this study we sampled stream water along multiple altitudinal transects to determine the effect unique seasonal patterns of precipitation have on the isotopic composition of surface water our results suggest that the northern tian shan exhibits an isotopic lapse rate for waters sampled in late spring but not for those sampled in late summer when stream water budgets are dominated by high elevation precipitation and snow melt deuterium excess results suggest that subcloud evaporation significantly affects the isotopic composition of precipitation at low elevations in spring and that sublimation of snow has a minor impact on 18o values of summer melt water because high and low elevation 18o values are similar conventional paleoaltimetry based on rayleigh distillation of an air mass is not applicable to the kyrgyz tian shan stream water proxies from the rock record are likely to reflect changes in the seasonal distribution of precipitation which occur on the same spatial scale as altitudinal changes these results highlight the need to understand modern controls on local stable isotopes of meteoric water in reconstructions of past climate or topography using geologic proxy materials

seasonal deuterium excess in a tien shan ice core influence of moisture transport and recycling in central asia 1 stable water isotope 18o d data from a high elevation 5100 masl ice core recovered from the tien shan mountains kyrgyzstan display a seasonal cycle in deuterium excess d d 8 18o related to changes in the regional hydrologic cycle during 1994 2000 while there is a strong correlation r2 0 98 between 18o and d in the ice core samples the regression slope 6 9 and mean d value 23 0 are significantly different than the global meteoric water line values the resulting time series ice core d profile contains distinct winter maxima and summer minima with a yearly d amplitude of 15 20 local scale processes that may affect d values preserved in the ice core are not consistent with the observed seasonal variability data from central asian monitoring sites in the global network of isotopes in precipitation gnip have similar seasonal d changes we suggest that regional scale hydrological conditions including seasonal changes in moisture source transport and recycling in the caspian aral sea region are responsible for the observed spatial and temporal d variability

enhancement of the total horizontal gradient of magnetic anomalies using the tilt angle abstractmagnetic anomaly maps reflect the spatial distribution of magnetic sources which may be located at different depths and have significantly different physical and geometrical properties complicating the identification of the corresponding geologic structures filtering techniques are frequently used to balance anomalies from shallow and deep sources and to enhance certain features of interest such as the edges of the causative bodies most methods used for enhancing magnetic data are based on vertical or horizontal derivatives of the magnetic anomalies or combinations of them and the edges or centers of the sources are identified by maxima minima or null values in the transformed data normalized derivatives methods are used to equalize signals from sources buried at different depths we present an edge detector method for the enhancement of magnetic anomalies which is based on the tilt angle of the total horizontal gradient the notable features of this method are that it produces amplitud

footwall uplift in an orogenic wedge the tauern window in the eastern alps of europe abstract in the tauern window tw the deepest structural units of the eastern alps are exposed in a 30 160 km antiform european basement and cover occur under nappes of oceanic penninic units and continental origin austroalpine nappes the tertiary structural history of the tw is related to a rapid uplift of 20 30 km since oligocene times structural mapping revealed 1 detachment and folding of the cover units and stacking of orthogneiss sheets 2 constrictional folding of the entire duplex with amplitudes and half wavelengths of several kilometres 3 backthrusting and backfolding along the northern margin of the tw and 4 displacement along steep dip divergent strike slip faults the strain history is complex and related to all these deformation phases the most uniform structural element is a stretching parallel to the long axis of the tw and its major fold axes strain did not contribute to tw uplift because ductile n s shortening was compensated by e w extension restoration of the tw shows that the exposed structures are not sufficient to explain the tw uplift by analogy with the engadine window and the western alps where seismic data are available a deep seated duplex is suspected the tw uplift is best explained in a dextral transpressive regime

directional filtering for linear feature enhancement in geophysical maps geophysical maps of data acquired in ground and airborne surveys are extensively used for mineral groundwater and petroleum exploration lineaments in these maps are often indicative of contacts basement faulting and other tectonic features of interest to aid the interpretation of these maps a versatile processing technique of directional filtering based on the 2 d normal radon transform is used to enhance or suppress specific lineaments synthetic data and field examples using electromagnetic and radiometric data are used to demonstrate the superiority of the radon transform method over conventional fourier transform filtering the radon transform technique is shown to be more versatile and less susceptible to processing artefacts than the fourier transform methods

ice core evidence of westerly and monsoon moisture contributions in the central tibetan plateau stable isotopes are a primary tool for inferring past temperature changes and atmospheric moisture variability from ice cores a 33 m ice core representing the period 1850 2004 was retrieved from the tanggula mountains central tibetan plateau 5743 m a s l in august 2005 annual average stable isotope d 18 o dd values generally increase during the period while the second order parameter of deuterium excess d excess generally decreases high annual average d excess values 18 2 throughout the ice core suggest a significant contribution of continental recycled moisture d excess values shift from relatively higher values during 1850 1940 to lower values since the 1940s annual isotope values and reconstructed accumulation are compared with climate indices local station temperature records and northern india monsoon precipitation significant correlation is observed between d 18 o and the southern oscillation nino3 4 and dipole mode indices annual average d excess values revealed a significant negative correlation with the dipole mode index results suggest a relatively greater contribution of westerly dominated continental moisture prior to the 1940s and an increase in the contribution of moisture evaporated under more humid conditions since the 1940s

stable isotopic variations in west china a consideration of moisture sources 1 in this study individual precipitation samples collected over 2 years at stations in different climatic regions of west china tibetan plateau region tianshan region and altay were analyzed for the stable isotopes of precipitation to improve our understanding of how vapor transport impacts the modern stable isotopic distribution our results identify regional patterns in both 18o and deuterium excess d excess defined as d 8 18o and in particular we have identified the northward maximum extent of the southwest monsoon over the tibetan plateau this demarcation is also the boundary for the fractionation effect of temperature on stable isotopes in precipitation the patterns we have identified are as follows 1 in the southern tibetan plateau along the southern slope of the himalayas our results show a distinct seasonality for both 18o and d excess as a result of the shift of summer monsoon moisture and winter westerly moisture transport the signals of 18o in the western tibetan plateau reveal that the region receives southwest monsoonal moisture in the east of the plateau stable isotopic variation shows alternation between monsoon intrusion and recycling of northern moisture 2 in contrast in tianshan there is an apparent temperature effect in 18o with enriched values occurring in summer and depleted values occurring in winter seasonal d excess values opposite to those observed in the southern tibetan plateau are controlled by differing seasonal evaporation conditions 3 in altay the most northern mountain region the seasonal 18o shows the same variation with that in tianshan region however d excess shows no apparent seasonal variation

an automatic network extraction algorithm applied to magnetic survey data for the identification and extraction of geologic lineaments lineament analysis is commonly undertaken by interpreting a wide range of geoscientific data to delineate geologic structures these structures include faults fractures dykes and lithological contacts which provide information for geologic mapping and mineral and energy exploration we offer a simple automatic lineament analysis method that combines the principles of peak identification algorithms typically used in geophysical data interpretation and a gis drainage network extraction algorithm commonly applied to a topographic surface we apply this network extraction process to a magnetic surface grid rather than a topographic one the gis approach calculates the curvature of a surface to determine whether a specific coordinate is at a minimum trough a simple quadratic surface is computed for a moving 3 3 window to determine if the local surface has the form of a dipping plane or a trough continuity of troughs between adjacent kernels defines lineaments that typically correspond to stream

improved edge detection mapping through stacking and integration a case study in the bathurst mining camp airborne geophysical surveys provide spatially continuous regional data coverage which directly reflects subsurface petrophysical differences and thus the underlying geology a modern geologic mapping exercise requires the fusion of this information to complement what is typically limited regional outcrop often interpretation of the geophysical data in a geological context is done qualitatively using total field and derivative maps with a qualitative approach the resulting map product may reflect the interpreter s bias source edge detection provides a quantitative means to map lateral physical property changes in potential and non potential field data there are a number of source edge detection algorithms all of which apply a transformation to convert local signal inflections associated with source edges into local maxima as a consequence of differences in their computation the various algorithms generate slightly different results for any given source depth geometry contrast and noise levels to enhance the viability of any detected edge it is recommended that one combines the output of several source edge detection algorithms here we introduce a simple data compilation method deemed edge stacking which improves the interpretable product of source edge detection through direct gridding grid addition and amplitude thresholding in two examples i e a synthetic example and a real world example from the bathurst mining camp new brunswick canada a number of transformation algorithms are applied to gridded geophysical data sets and the resulting source edge detection solutions combined edge stacking combines the benefits and nuances of each source edge detection algorithm coincident or overlapping and laterally continuous solutions are considered more indicative of a true edge whereas isolated points are taken as being indicative of random noise or false solutions when additional data types are available as in our example they may also be integrated to create a more complete geologic model the effectiveness of this method is limited only by the resolution of each survey data set and the necessity of lateral physical property contrasts the end product aims at creating a petrophysical contact map which when integrated with known lithological outcrop information can be led to an improved geological map

new developments of the magnetic tilt depth method to improve structural mapping of sedimentary basins this paper interprets aeromagnetic data for a deep basin section of the karroo rift in south east tanzania we use a novel integrated approach involving the application of advanced derivatives to define structure and the tilt depth method to determine and map the depth to basement in the latter case we use the result of both reduced to pole and reduced to equator data to help constrain the shape and depth of the basin we show that for a reduced to pole aeromagnetic data set the generalized form of the local phase called the tilt derivative is an effective means of providing an initial first pass mapping of a sedimentary basin in terms of its fault structure dip direction of faults and depth to basement since the amplitude of the tilt derivative does not contain information on the strength of the geomagnetic field nor magnetization other than inclination of the causative body the susceptibility contrast across faults contacts is derived from the analytic signal derivative we also investigate how effective the tilt derivative and tilt depth method are for structural and depth to basement mapping in regions close to the magnetic equator where the reduction to pole transform is often unstable this is done using the same tanzania data set transformed to the pole and the equator we find that the tilt derivative applied to the reduction to equator data cannot be used to map the structure because of the effects of magnetic anisotropy which results in the magnetic response of structures varying with strike azimuth to overcome this anisotropy problem the analytic signal and or local wavenumber derivatives which are for all practical purposes independent of inclination provide the best means of defining the major structural trends we also find that the tilt depth method provides coherent depth to basement estimates for both reduced to pole and reduced to equator data for the deep basin sections of the karroo rift there is a sparsity of tilt depth results from both the reduced to pole and reduced to equator data sets however each set of results has a different spatial coverage so when combined they provide a better spatial sampling of the long wavelength magnetic character of the basin and thus improve the constraints on the minimum curvature gridding method to map the shape and depth of the basin

multiscale derivative analysis a new tool to enhance detection of gravity source boundaries at various scales 1 potential fields generally require to be analyzed by different scales owning to sources of different depth and extent fourier or wavelet filtering not always yield an optimal separation of those different source effects often introducing some amount of distortion we propose therefore a new method the multiscale derivative analysis mda based on the enhanced horizontal derivative ehd of the field which does not imply any separation of the effects but simply enhances those related to a given scale such process based on a weighted sum of increasing order derivatives of the field converges quickly toward the actual boundaries of the sources mda applied to gravity data of the of thyrrenian sea italia yields 3 maps of structural lineaments each one characterized by a different scale known partially known or relatively new structures are described in the maps allowing a rapid analysis of all the gravity related structural lineaments of this region

indentation model of the eastern alps and the origin of the tauern window a lithospheric model scaled for density and viscosity was shortened obliquely in front of an indenter whose shape and orientation match those of the south alpine indenter deformation was initially localized into subparallel sets of conjugate transpressive thrusts these structures evolved into folds which were strongly amplified and converged closer together during ongoing shortening finally forming a series of tight antiforms at the same time this tightly folded structure locally accommodated significant orogen parallel extension attaining 100 in front of the leading edge of the indenter but only 15 on the scale of the entire model the internal architecture and fault pattern of the model in map view are very similar to those of the tauern window in the eastern alps emphasizing the importance of localization of folding and shortening rather than orogen parallel extension for its formation

stable isotope and trace element time series from fedchenko glacier pamirs snow firn cores in summer 2005 two pilot snow firn cores were obtained at 5365 and 5206 m a s l on fedchenko glacier pamirs tajikistan the world s longest and deepest alpine glacier the well defined seasonal layering appearing in stable isotope and trace element distribution identified the physical links controlling the climate and aerosol concentration signals air temperature and humidity precipitation were the primary determinants of stable isotope ratios most precipitation over the pamirs originated in the atlantic in summer water vapor was re evaporated from semi arid regions in central eurasia the semi arid regions contribute to non soluble aerosol loading in snow accumulated on fedchenko glacier in the pamir core concentrations of rare earth elements major and other elements were less than those in the tien shan but greater than those in antarctica greenland the alps and the altai the content of heavy metals in the fedchenko cores is 2 14 times lower than in the altai glaciers loess from afghan tajik deposits is the predominant lithogenic material transported to the pamirs trace elements generally showed that aerosol concentration tended to increase on the windward slopes during dust storms but tended to decrease with altitude under clear conditions the trace element profile documented one of the most severe droughts in the 20th century

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

climatic and atmospheric circulation pattern variability from ice core isotope geochemistry records altai tien shan and tibet several firn ice cores were recovered from the siberian altai belukha plateau central tien shan inilchek glacier and the tibetan plateau zuoqiupu glacier bomi from 1998 to 2003 the comparison analyses of stable isotope geochemistry records obtained from these firn ice cores identified the physical links controlling the climate related signals at the seasonal scale variability the core data related to physical stratigraphy meteorology and synoptic atmospheric dynamics were the basis for calibration validation and clustering of the relationships between the firn ice core isotope geochemistry and snow accumulation air temperature and precipitation origin the mean annual accumulation in water equivalent was 106 g cm 2 a 1 at inilchek glacier 69 g cm 2 a 1 at belukha and 196 gc m 2 a 1 at zuoqiupu the slopes in regression lines between the d 18 o ice core records and air temperature were found to be positive for the tien shan and altai glaciers and negative for southeastern tibet where heavy amounts of isotopically depleted precipitation occur during summer monsoons the technique of coupling synoptic climatology and meteorological data with d 18 o and d excess in firn core records was developed to determine climate related signals and to identify the origin of moisture in altai two thirds of accumulation from 1984 to 2001 was formed from oceanic precipitation and the rest of the precipitation was recycled over aral caspian sources in the tien shan 87 of snow accumulation forms by precipitation originating from the aral caspian closed basin the eastern mediterranean and black seas and 13 from the north atlantic

upper mantle structure beneath the alpine orogen from high resolution teleseismic tomography 1 to understand the evolution of the alpine orogen knowledge of the actual structure of the lithosphere asthenosphere system is important we perform high resolution teleseismic tomography with manually picked p wave arrival times from seismograms recorded in the greater alpine region the resulting data set consists of 4199 relative p wave arrivals and 499 absolute p wave arrivals from 76 teleseismic events corrected for the contribution of the alpine crust to the travel times the three dimensional 3 d crustal model established from controlled source seismology data for that purpose represents the large scale alpine crustal structure absolute p wave arrival times are used to compute an initial reference model for the inversion tests with synthetic data document that the combination of nonlinear inversion high quality teleseismic data and usage of an a priori 3 d crustal model allows a reliable resolution of cells at 50 km 50 km 30 km hence structures as small as two cells can be resolved in the upper mantle our tomographic images illuminate the structure of the uppermost mantle to depth of 400 km along strike of the alps the inversion reveals a high velocity structure that dips toward the se beneath the adriatic microplate in the western and central alps in the eastern alps we observe a northeastward dipping feature subducting beneath the european plate we interpret this feature in the western and central alps as subducted mainly continental european lower lithosphere for the east we propose that parts of the vardar oceanic basin were subducted toward the ne forcing continental adriatic lower lithosphere to subduct northeastward beneath the european plate

transalp deep crustal vibroseis and explosive seismic profiling in the eastern alps abstract the transalp consortium comprising institutions from italy austria and germany carried out deep seismic reflection measurements in the eastern alps between munich and venice in 1998 1999 and 2001 in order to complement each other in resolution and depth range the vibroseis technique was combined with simultaneous explosive source measurements additionally passive cross line recording provided three dimensional control and alternative north south sections profits were obtained by the combination of the three methods in sectors or depths where one method alone was less successful the transalp sections clearly image a thin skinned wedge of tectonic nappes at the northern alpine front zone unexpected graben or half graben structures within the european basement and thick skinned back thrusting in the southern frontal zone beneath the dolomite mountains a bi vergent structure at crustal scale is directed from the alpine axis to the external parts the tauern window obviously forms the hanging wall ramp anticline above a southward dipping deep reaching reflection pattern interpreted as a tectonic ramp along which the penninic units of the tauern window have been up thrusted the upper crystalline crust appears generally transparent the lower crust in the european domain is characterized by a 6 7 km thick laminated structure on the adriatic side the lower crust displays a much thicker or twofold reflective pattern the crustal root at about 55 km depth is shifted around 50 km to the south with respect to the main alpine crest

comprehensive approaches to 3d inversion of magnetic data affected by remanent magnetization three dimensional 3d inversion of magnetic data to recover a distribution of magnetic susceptibility has been successfullyusedformineralexplorationduringthelastdecade however the unknown direction of magnetization has limited the use of this technique when significant remanence is present we have developed a comprehensive methodology for solving this problem by examining two classes of approaches and have formulated a suite of methods of practical utility the first class focuses on estimating total magnetization direction and then incorporating the resultant direction into an inversion algorithm that assumes a known direction thesecondclassfocusesondirectinversionoftheamplitude of the magnetic anomaly vector amplitude data depend weaklyuponmagnetizationdirectionandareamenabletodirect inversion for the magnitude of magnetization vector in 3d subsurface two sets of high resolution aeromagnetic dataacquiredfordiamondexplorationinthecanadianarctic areusedtoillustratethemethods usefulness

skeletonization of aeromagnetic data skeletonization is a syntactic pattern recognition method that is applied to gridded data to produce an automatic line drawing with an associated event catalog previous implementations of skeletonization have been tailored for seismic data here we modify that technique to render it more suitable for other types of gridded data with particular emphasis on aeromagnetic maps a modification from previous schemes is the use of a two pass approach to reduce the effects of an otherwise problematic directional bias that discriminates against events oriented parallel to columns of the grid the method can be used effectively for filtering aeromagnetic data on the basis of strike direction event linearity event amplitude and polarity it is based on the delineation of peak trough pairs cycles which are traced throughout the grid to form contiguous events cycles and events are characterized by attributes that include amplitude polarity and pulse width events are further characterized by length average strike direction and linearity the event attributes are stored in a catalog thus enabling one to perform attribute based analysis and data filtering we illustrate our algorithm using two regional aeromagnetic examples from different parts of the canadian shield the first from the great slave lake shear zone is dominated by linear anomaly trends produced by faults and mafic dikes the second from the manicouagan region of northeastern quebec contains abundant subcircular and arcuate anomaly patterns caused by large intrusive complexes and a meteorite impact structure

first deep seismic reflection images of the eastern alps reveal giant crustal wedges and transcrustal ramps 1 the alps are considered as a classical example for an orogen created by continental plate collision in this study we present new images obtained from deep seismic reflection profiling in the eastern alps between munich and venice which give rise to examine and revise existing concepts the seismic sections exhibit a prominent bi verging reflection pattern at crustal scale a major ramp like structure outcropping at the inn valley fault can be traced southward over 80 km into the mountain root where relics of the subducted penninic ocean are expected new models of the evolution of the eastern alps show an upper lower crustal decoupling along transcrustal thrust faults with opposite thrust directions of both the european and the adriatic african continents

deuterium excess record in a southern tibetan ice core and its potential climatic implications a 55 m long ice core drilled close to bedrock from mt noijin kangsang on the southern tibetan plateau in summer 2007 was annually dated covering the period of 1864 2006 ad the stable isotope ratios 18o and d of the ice core were measured and thereby the deuterium excess d was calculated by d d 8 18o for the individual ice samples results show that the d values of the ice samples were predominantly controlled by the moisture sources the significant increasing trend of annual mean d values along the ice core is mainly related to the rapid warming of the tropical indian ocean although the tendency is subjected to the modulation by the western derived moisture the decreasing indian monsoon precipitation on the southern tibetan plateau physically linked with the increasing tropical indian ocean sst reduced the share of monsoon precipitation in the annual total accumulation making an additional contribution to the significant increase of annual mean d in the noijin kangsang ice core with high values during the past 143 years

automatic boundary extraction from magnetic field data using triangular meshes boundary extraction is a collective term that we use for the process of extracting the locations of faults lineaments and lateral boundaries between geologic units using geophysical observations such as measurements of the magnetic field the process typically begins with a preprocessing stage where the data are transformed to enhance the visual clarity of pertinent features and hence improve the interpretability of the data the majority of the existing methods are based on raster grid enhancement techniques and the boundaries are extracted as a series of points or line segments in contrast we set out a methodology for boundary extraction from magnetic data in which we represent the transformed data as a surface in 3d using a mesh of triangular facets after initializing the mesh we modify the node locations such that the mesh smoothly represents the transformed data and that facet edges are aligned with features in the data that approximate the horizontal locations of subsurface boundaries to illustrate our boundary extraction algorithm we first apply it to a synthetic data set we then apply it to identify boundaries in a magnetic data set from the mcfaulds lake area in ontario canada the extracted boundaries are in agreement with known boundaries and several of the regions that are completely enclosed by extracted boundaries coincide with regions of known mineralization

oxygen isotopic and soluble ionic composition of a shallow firn core inilchek glacier central tien shan oxygen isotopic and soluble ionic measurements made on snow pit 2 m depth and firn core 12 4 m depth samples recovered from the accumulation zone 5100 m of inilchek glacier 43 n 79 e provide information on recent 1992 98 climatic and environmental conditions in the central tien shan region of central asia the combined 14 4 m snow pit firn core profile lies within the firn zone and contains only one observed melt feature 10 m temperature 12 c although some post depositional attenuation of the sub seasonal 18 o record is possible annual cycles are apparent throughout the isotope profile we therefore use the preserved 18 o record to establish a depth age scale for the core mean 18 o values for the entire core and for summer periods are consistent with 18 temperature observations and suggest the 18 o record provides a means to reconstruct past changes in summer surface temperature at the site major ion na k mg 2 ca 2 nh 4 cl no 3 so 4 2 data from the core demonstrate the dominant influence of dust deposition on the soluble chemistry at the site and indicate significant interannual variability in atmospheric dust loading during the 1990s anthropogenic impacts on nh 4 concentrations are observed at the site and suggest a summer increase in atmospheric nh 4 that may be related to regional agricultural nitrogen rich fertilizer use activities

tectonic style and pressure distribution at the northern margin of the alps between lake constance and the river inn hydrocarbon exploration in the molasse basin and the alpine thrust belt has provided new information on the tectonic structure of the foreland margin of the overthrust belt two n s cross sections show the front of the folded molasse as a so called triangle zone in the area north of the hindelang 1 well bavaria and the sulzberg 1 well vorarlberg the triangle zone was described and defined byjones 1982 for the alberta foothills in canada

a twentieth century major soluble ion record of dust and anthropogenic pollutants from inilchek glacier tien shan using a high resolution 18 samples year major soluble ion record na k mg2 ca2 cl no3 and so42 covering the period 1908 1995 ad from the inilchek glacier tien shan kyrgyzstan we provide a detailed climate and environmental proxy record for the region chemical concentrations empirical orthogonal function analyses and non crustal excess calculations are used to identify natural and potential anthropogenic depositional trends dominant dust proxy species i e ca2 reveal highest concentrations during the 1950s 1970s with declining decadal trends through the end of the record these trends likely reflect decreases in central asian dust storm activity post 1950 which has been associated with coupled atmospheric circulation variability and anthropogenic activities comparison between ca2 and era interim 1979 1995 climate reanalysis data indicates a strong relationship to spring march april and may geopotential height patterns in northwest china and southern siberia associated with the siberian high non crustal contribution excess estimates of no3 k so42 and cl concentrations suggest discernable anthropogenic inputs began between the 1950s 1970s increased into the mid late1980s and declined in the 1990s excess trends coincide with former soviet union fsu consumption production and emission of fossil fuels and fertilizers reflecting the rapid growth of agriculture and industry as well as economic declines in the mid late 1980s early 1990s excess cl trends reflect timings that coincide with the construction of the pavlodar chemical plant and the military production of cl2 in kazakhstan noaa hysplit back trajectory frequency analysis suggests eastern uzbekistan e g fergana valley kyrgyzstan and southern kazakhstan as the primary pollutant sources to the study region

a high resolution diatom inferred palaeoconductivity and lake level record of the aral sea for the last 1600 yr formerly the world s fourth largest lake by area the aral sea is presently undergoing extreme desiccation due to large scale irrigation strategies implemented in the soviet era as part of the intas funded climan project into holocene climatic variability and the evolution of human settlement in the aral sea basin fossil diatom assemblages contained within a sediment core obtained from the aral sea have been applied to a diatom based inference model of conductivity r2 0 767 rmsep 0 469 log10 s cm 1 this has provided a high resolution record of conductivity and lake level change over the last ca 1600 yr three severe episodes of lake level regression are indicated at ca ad 400 ad 1195 1355 and ca ad 1780 to the present day the first two regressions may be linked to the natural diversion of the amu darya away from the aral sea and the failure of cyclones formed in the mediterranean to penetrate more continental regions human activity however and in particular the destruction of irrigation facilities are synchronous with these early regressions and contributed to the severity of the observed low stands

crustal structure of the eastern alps along the transalp profile from wide angle seismic tomography abstract the objective of the transalp project is an investigation of the eastern alps with regard to their deep structure and dynamic evolution the core of the project is a 340 km long seismic profile at 12 e between munich and venice this paper deals with the p wave velocity distribution as derived from active source travel time tomography our database consists of vibroseis and explosion seismic travel times recorded at up to 100 seismological stations distributed in a 30 km wide corridor along the profile in order to derive a velocity and reflector model we simultaneously inverted refractions and reflections using a derivative of a damped least squares approach for local earthquake tomography 8000 travel time picks from dense vibroseis recordings provide the basis for high resolution in the upper crust explosion seismic wide angle reflection travel times constrain both deeper crustal velocities and structure of the crust mantle boundary with low resolution in the resulting model the adriatic crust shows significantly higher p wave velocities than the european crust the european moho is dipping south at an angle of 7 the adriatic moho dips north with a gentle inclination at shallower depths this geometry suggests s directed subduction azimuthal variations of the first break velocities as well as observations of shear wave splitting reveal strong anisotropy in the tauern window we explain this finding by foliations and laminations generated by lateral extrusion based on the p wave model we also localized almost 100 local earthquakes recorded during the 2 month acquisition campaign in 1999 seismicity patterns in the north seem related to the inn valley shear zone and to thrusting of austroalpine units over european basement the alignment of deep seismicity in the trento vicenza region with the top of the adriatic lower crust corroborates the suggestion of a deep thrust fault in the southern alps