late paleozoic glacial episodes in gondwanaland reflected in transgressive regressive depositional sequences in euramerica the late paleozoic glaciation of gondwanaland comprised two short episodes in the famennian i and visean ii confined to brazil and adjacent northwest africa and a long episode that started in the namurian iiia of eastern australia and bolivia argentina expanded to cover much of gondwanaland in the stephanian asselian iiib and collapsed in the early sakmarian iiic dropstones in eastern australia indicate that small ice centers lingered to the kazanian across the belt of low latitudes north of gondwanaland short ranging fossils in widespread shallow marine and paralic deposits indicate synchronous deposition of transgressive regressive sequences in different parts of euramerica these sequences correlate with glacial events in gondwanaland at three levels a four major regressions in euramerica in the famennian 1 visean 2 namurian 3 stephanian 4 and the tastubian transgression that preceded the sterlitamakian regression 5 also recorded in gondwanaland correlate with glacial episodes i ii and iiia iiib and iiic b the time interval of cyclothemic deposition in euramerica brigantian or latest visean to sterlitamakian correlates with that of glacial episode iii and c the dominant period of the euramerican cyclothems as estimated from the middle and late pennsylvanian deposits of the mid continent of north america and of the thickest known gondwanaland glacigenic sediment the earliest permian lyons group of western australia is 0 4 ma equivalent in turn to the long orbital eccentricity period of the quaternary ice age and the dominant period of fluctuation of the late miocene antarctic ice cap the three levels of correlations confirm wanless and shepard9s 1936 hypothesis that the late paleozoic cyclothems are controlled largely by sea level fluctuations related to the gondwanaland glaciation

carbon and oxygen isotope stratigraphy of the lower mississippian kinderhookian lower osagean western united states implications for seawater chemistry and glaciation a positive carbon isotope 1 3 c excursion has been recognized in upper kinderhookian and early osagean carbonates in three sections in southeast idaho and nevada the oldest 1 3 c peak 7 is dated to the isostichaconodont zone and a younger peak occurs in the typicus zone the shifts are recorded in a range of carbonate lithofacies representing various water depths along the shelf lithofacies sampled for 1 3 c and 1 8 o at the samaria mountain section in southeast idaho record the shallowest water conditions indicated by cross bedded skeletal and peloidal grainstones the deepest water conditions are present in the pahranagat range section in eastern nevada which consists mainly of bioturbated lime mudstone and skeletal wackestone the 1 3 c values from these widely separated sedimentary basins show a consistent trend that correlates with early mississippian curves generated from brachiopod calcite in western europe and the midcontinent of north america as well as dolomites in utah and wyoming 1 8 o values become more positive up section generally paralleling the positive trend in 1 3 c during the late kinderhookian no subaerial exposure surfaces are recognized in the sections examined in southeast idaho and nevada and at least the 1 3 c trends are interpreted as primary seawater fluctuations sea level changes occurred near the beginning of the late kinderhookian 1 3 c shift early to middle parts of the isosticha zone and within the peak of the 1 3 c excursion kinderhookian osagean boundary although tectonic changes associated with the antler orogeny have likely modified the eustatic signature

searching for eustasy in deglacial sea level histories abstract perturbations to the earth s gravity field and solid surface associated with glacial isostatic adjustment gia cause the total observable sea level change to depart from the eustatic curve which is defined as a spatially uniform height shift of the ocean surface to accommodate any mass gained lost from grounded ice in this study we apply a state of the art model of gia induced sea level change to quantify the magnitude and spatial form of this departure at the global scale for a range of model parameters with an aim to identify regions that are well suited to obtain accurate and precise estimates of eustatic sea level and therefore past grounded ice volume in general our results indicate that eustatic sea level is not a directly measurable quantity and so must be estimated by subtracting a model derived estimate of non eustatic contributions from observations in this regard we use our results to isolate regions where this procedure can be applied with optimal accuracy and precision that is where 1 the gia predictions are relatively insensitive to plausible ranges in input parameters and 2 where the non eustatic contribution is small i e the predicted sea level closely approximates the eustatic value we present maps that can be employed by the field community to identify areas where sea level reconstructions would be well suited to arrive at robust estimates of eustatic sea level note that sea level changes associated with tectonic motion and changes in ocean water temperature salinity which also lead to departures from eustasy are not considered in this analysis

velocity field of the la clapiere landslide measured by the correlation of aerial and quickbird satellite images 1 two displacement maps of the la clapiere landslide france have been derived over two periods of 4 years 1995 1999 and 1999 2003 by correlation of aerial photographs and a quickbird satellite image the movement of the landslide ranges from 2 5 m to 20 m per year those values have been validated over 13 points monitored by conventional tacheometric measurements three areas with significant differences in velocity field have been mapped limits of those areas are in good agreement with in situ observations velocity maps show the low long term temporal variability of the landslide movement and its spatial variability the optical correlation method using images derived from various sensors airborne and spatial is a promising technique for improving the spatial resolution of velocity field observation of landslides over several years

stratigraphic architecture of the cenozoic succession in the mcmurdo sound region antarctica an archive of polar palaeoenvironmental change in a failed rift setting the victoria land basin forms part of the failed west antarctic rift and preserves a cenozoic succession up to 4 km thick that records the onset of cenozoic glaciation and the history of antarctic glaciation over the past 34 myr this succession is relevant both to investigations of modern climate change and to studies of long term palaeoclimate change in general this study provides a sedimentological and stratigraphic review of the victoria land basin succession based on analysis of several continuous drillcores acquired since the 1970s and supported by seismic stratigraphic analysis of a large array of seismic reflection data an array of fifteen lithofacies is recognized within the victoria land basin cenozoic succession including fossiliferous and diversely bioturbated mudrocks and diatomites texturally mature sandstones and conglomerates mixed mudstones and sandstones with dispersed gravel with restricted bioturbation and diamictites and associated lithologies these facies record a variety of marine glaciomarine proglacial and subglacial environments locally volcanic and volcaniclastic deposits are interbedded in the succession lithofacies are arranged in repetitive vertical stacking patterns depositional sequences that record glacial advance retreat cycles with attendant relative sea level changes seven varieties of depositional sequences stratigraphic motifs are recognized within the succession as a whole and interpreted to record a range of depositional settings from rifts unaffected by glacial ice motif 7 through varying degrees of glacial influence with abundant meltwater contributions motifs 6 to 3 to cold polar glaciated environments such as that of today motifs 2 and 1 overall there is a gradual trend upward through the succession from motif 7 at the base towards motif 1 at the top but the trend is not monotonic a significant conclusion of this work is that a record of dynamic climate and glacial conditions is preserved through the entire 34 myr period of the cenozoic icehouse at least in the victoria land basin intervals characterized by consistent stratigraphic style motifs are recognized throughout the victoria land basin succession these intervals are of 1 to 6 myr duration each containing numerous depositional sequences they are one to two orders of magnitude longer than glacial interglacial cycles and record periods during which environmental conditions varied in an internally consistent manner these intervals are considered to reflect convolutions of orbital parameters that remained stable for periods of 106 a and then switched to alternative configurations such intervals are directly analogous to 1 to 8 myr intervals characterized by glaciogenic strata that are preserved within the late palaeozoic of eastern australia among other areas and may be a recurring stratigraphic response to icehouse climate regimes through geological time

earthquake driven acceleration of slow moving landslides in the colca valley peru detected from pleiades images abstract major earthquakes in mountainous areas often trigger rapid landslides some observations also suggest that earthquakes can damage landslide prone areas or cause slow moving landslides to accelerate with a risk of evolution to rapid landslides in the following months after the earthquake here we use optical images from the pleiades satellites to detect slow moving landslides and quantify the effect of earthquakes on the landslide motion we process multi temporal pleiades images acquired in march april and july 2013 over an area of 210 km2 in the colca valley south peru to obtain two digital elevation models dem and three displacement fields of the area the processed dems have an uncertainty of 0 6 m 1 an order of magnitude better than two global and freely available dems gdem v2 and srtm whereas the displacement fields have an uncertainty of between 0 11 and 0 18 m 1 in both horizontal directions using these data we detect 9 slow moving landslides and compare their velocities during the march april and april july periods we find that landslide velocities are highest during the wet season which suggests a strong groundwater control and we also highlight a landslide acceleration caused by a regional mw 6 0 earthquake the major parameters controlling the acceleration of the slow moving landslides are the rock type and the distance to the source suggesting that friction at the basal interface in the weeks after the earthquake is dependent on the shaking intensity

petrological geochemical isotopic and geochronological constraints for the late devonian early carboniferous magmatism in sw gondwana 27 32 ls an example of geodynamic switching we report a study integrating 13 new u pb la mc icp ms zircon ages and hf isotope data from dated magmatic zircons together with complete petrological and whole rock geochemistry data for the dated granitic rocks sample selection was strongly based on knowledge reported in previous investigations latest devonian early carboniferous granite samples were collected along a transect of 900 km from the inner continental region present day eastern sierras pampeanas to the magmatic arc now western sierras pampeanas and frontal cordillera based on these data together with ca 100 published whole rock geochemical analyses we conclude that late devonian early carboniferous magmatism at this latitude represents continuous activity ranging from 322 to 379 ma on the pre andean margin of sw gondwana although important whole rock and isotopic compositional variations occurred through time and space combined whole rock chemistry and isotope data reveal that peraluminous a type magmatism started in the intracontinental region during the late devonian with subsequent development of synchronous carboniferous peraluminous and metaluminous a type magmatism in the retro arc region and calc alkaline magmatism in the western paleomargin we envisage that magmatic evolution was mainly controlled by episodic fluctuations in the angle of subduction of the oceanic plate between flat slab and normal subduction supporting a geodynamic switching model subduction fluctuations were relatively fast ca 7 ma during the late devonian and early carboniferous and the complete magmatic switch off and switch on process lasted for 57 ma hf tdm values of zircon igneous and inherited from some carboniferous peraluminous a type granites in the retro arc suggest that gondwana continental lithosphere formed during previous orogenies was partly the source of the devonian carboniferous granitic magmas thus precluding the generation of the parental magmas from exotic terranes

constraining the timing kinematics and cyclicity of mississippian early pennsylvanian glaciations in the parana basin brazil abstract ice contact deposits emplaced by late paleozoic ice age lpia glaciers are rarely exposed due to a low degree of preservation and their capping by thick glaciomarine deglaciation sequences in this paper we present new data on glacial cyclicity relative age constraints and paleoice flow interpretations for an ice contact succession of the lowermost itarare group in eastern parana basin brazil the 80 m thick ice contact complex rests over the itarare group basal unconformity and comprises four stacked informal stratigraphic units regarded as the depositional deformational record of three ice lobes advance retreat cycles glacial cycle 1 comprises a sheet of massive diamictite resting on striated pavements carved on devonian sandstones and topped by grooved fluted surfaces which indicate subglacial emplacement from a northward flowing ice lobe the glacial cycle 2 succession was deposited in a proglacial to ice marginal marine setting and subsequently deformed due to minor ice margin fluctuations of a westward southwestward flowing grounded ice lobe glacial cycle 3 is interpreted as a thick overridden push moraine composed of grounding line fan deposits capped by a subglacial diamictite emplaced by grounded ice advancing northwestward a middle visean early serpukhovian palynomorph assemblage was recorded in cycle two deposits representing the oldest late paleozoic glacial rocks in the parana basin the ice contact complex elucidates multiple waxing and waning phases of the windhoek ice sheet onto the eastern margin of the parana basin during the mississippian early pennsylvanian demonstrating that ice sheets of the early stages of the lpia were also present in the brazilian african domain of southwestern gondwana

deformation due to the 17 august 1999 izmit turkey earthquake measured from spot images the geometry of the ruptured areas and the coseismic slip distribution data are key to highlighting the behavior of seismic faults this information is generally retrieved from field investigations and geodetic measurements or synthetic aperture radar sar interferometry here we show that spot images can also be used to accurately map the fault zone and to determine the slip distribution by subpixel correlation of images acquired before and after an earthquake the measured slip includes the contribution of possible distributed shear that might not be clearly expressed in surface ruptures and smoothes out possible along strike variability due to near surface fault complexities we apply the technique to the m s 7 4 1999 izmit earthquake our results reveal a 100 m wide and very linear fault zone that can be traced for 70 km from golcuk to akyazi along which supershear rupture has been inferred the obtained slip distribution compares well with the field measurements and is consistent with ground deformation measured at some distance from the fault zone using sar images very little deformation was accommodated off the main fault plane maximum slip is observed near sapanca lake at a small fault jog that has probably influenced rupture propagation

deformation between 1989 and 1997 at piton de la fournaise volcano retrieved from correlation of panchromatic airborne images we processed two panchromatic airborne images in the attempt to measure deformation on piton de la fournaise volcano between 1989 and 1997 piton de la fournaise erupted three times during 1989 1997 with fissures opening near dolomieu summit crater during this period no synthetic aperture radar interferometry data were available and only few geodetic points surveyed the summit crater we therefore apply for the first time the subpixel image correlation technique on airborne images for monitoring ground deformation on piton de la fournaise volcano correlogram analysis reveals cumulative deformation in the summit area we observe ese spreading of the summit caused by the inflation deflation cycle during 1989 1997 we calculated relative ground displacement along both sides of the main eruptive fissures finding a maximum of 1 8 0 42 m opening direct comparison between deformation retrieved by correlation and available geodetic data at four locations shows qualitative agreement we demonstrate the potential of subpixel image correlation technique using panchromatic airborne images for deformation monitoring on volcanoes we also illustrate the capability of this technique for remote lava flow mapping

inversion of deformation fields time series from optical images and application to the long term kinematics of slow moving landslides in peru abstract slow moving landslides are numerous in mountainous areas and pose a large threat to populations many observations show that their kinematics is driven by climatic forcings and earthquakes in this study we document the complex interaction between those two forcings on the slow moving landslide kinematics based on the retrieval of landslide displacements over 28 years using optical satellite images to overcome the decorrelation effect over this large time span and possible misalignment between images we develop a method that uses the redundancy of displacement fields from image pairs to derive a robust time series of displacement the method is tested on the 28 year long spot1 5 pleiades archive over an area in peru affected by both earthquakes and rainfall errors are estimated on stable areas and by comparison with one 13 year long and eleven 3 year long gps time series on the maca landslide the methodology diminishes by up to 30 the uncertainty and reduces significantly the gaps due to decorrelation the data set allows detecting 3 major landslides moving at a rate of 35 to 50 m over 28 years and smaller landslides with lower displacement rates time series obtained over the three main landslides provide interesting results of their long term kinematics primarily driven by precipitation we propose simple statistical hydro kinematic models relating yearly motion to seasonal rainfall to explain the observed time series we found that annual precipitation is controlling the landslide displacements after a certain rainfall threshold is reached besides this control we show the possible impact of a local mw 5 4 earthquake in 1991 on the kinematics of the maca landslide our results suggest that the earthquake accelerated the landslide and has an effect during several years on the precipitation threshold required for triggering a motion these results suggest that the rainfall threshold can vary in time following strong earthquakes shaking

deglacial and postglacial sedimentary architecture in a deeply incised paleovalley paleofjord the pennsylvanian late carboniferous jejenes formation san juan argentina quebrada de las lajas near san juan argentina preserves an early pennsylvanian deglacial postglacial succession in a highly confined paleofjord setting the sedimentary succession records four distinct stages in the evolution of the valley fill stage 1 is represented by the deposits of subglacial diamictites ice contact deltas and related deep water lacustrine environments including several subaqueous channels stage 2 records a glacio eustatic marine transgression and a slow down of the clastic supply into the paleofjord stage 3 records a sandy confined turbidite environment stage 4 consists of a coarse grained delta which represents a significant rejuvenation of the sedimentary system in the paleofjord the transition from stage 1 to stage 2 was abrupt and basinwide and has proven to be a good regional correlation marker in this paleovalley the glacio eustatic rise probably caused floating and consequent rapid melting of the valley glacier this resulted in a paleovalley wide turbidite event that is up to 5 m thick and indicates an overall waning character the rapid sediment emplacement in this event and resulting loading of the paleovalley sediments may have helped cause widespread mass transport events at the stage 1 2 boundary all stages show evidence of mass transport related deposits but stage 1 records the most widespread mass transport with a large spectrum of processes represented including coherently slumped material rafted blocks and completely mixed debris flow deposits these mass transport deposits range from a few meters to over 50 m thick and up to hundreds of meters wide and long most of the large mass transport deposits in the lower part of the fjord fill occurred at the transition to stage 2 implicating a rise in relative sea level as a possible trigger for the slope failures additionally stage 3 deposits were affected by several thrust sense dislocations that have large offsets relative to the scale of the sedimentary succession tens to over 50 m vertically and hundreds of meters laterally strata associated with the dislocations exhibit growth indicating very early movement and they are interpreted as the frontal ramp zones of mass transport deposits the abundance and size of mass transport deposits in stages 1 and 3 helped control sediment pathways throughout the paleofjord

evidence for slip partitioning and bimodal slip behavior on a single fault surface slip characteristics of the 2013 mw7 7 balochistan pakistan earthquake abstract deformation is commonly accommodated by strain partitioning on multiple independent strike slip and dip slip faults in continental settings of oblique plate convergence as a corollary individual faults tend to exhibit one sense of slip normal reverse or strike slip until whole scale changes in boundary conditions reactivate preexisting faults in a new deformation regime in this study we show that a single continental fault may instead partition oblique strain by alternatively slipping in a strike slip or a dip slip sense during independent fault slip events we use 0 5 m resolution optical imagery and sub pixel correlation analysis of the 200 km 2013 m w 7 7 balochistan pakistan earthquake to document co seismic surface slip characteristics and quaternary tectonic geomorphology along the causative hoshab fault we find that the 2013 earthquake which involved a 6 1 strike slip to dip slip ratio ruptured a structurally segmented fault quaternary geomorphic indicators of gross fault zone morphology reveal both reverse slip and strike slip deformation in the rupture area of the 2013 earthquake that varies systematically along fault strike despite nearly pure strike slip motion in 2013 observations of along strike variations in range front relief and geomorphic offsets suggest that the hoshab fault accommodates a substantial reverse component of fault slip in the quaternary especially along the southern section of the 2013 rupture we surmise that quaternary bimodal slip along the hoshab fault is promoted by a combination of the arcuate geometry of the hoshab fault the frictional weakness of the makran accretionary prism and time variable loading conditions from adjacent earthquakes and plate interactions

greenhouse to icehouse a biostratigraphic review of latest devonian mississippian glaciations and their global effects the latest devonian mississippian interval records the long term transition from devonian greenhouse conditions into the late palaeozoic ice age lpia this transition was punctuated by three short glaciation events in the latest famennian mid tournaisian and visean stages respectively primary evidence for glaciation is based on diamictite deposits and striated pavements in south america appalachia and africa the aim of this review is to assess the primary biostratigraphic and sedimentological data constraining diamictite deposits through this transition these data are then compared to the wider record of eustasy mass extinction and isotope stratigraphy in the lower palaeolatitudes precise age determinations are vital to integrate high and low palaeolatitude datasets and to understand the glacial control on wider global changes palynological techniques currently provide the best biostratigraphic tool to date these glacial deposits and to correlate the effects of glaciation globally this review highlights a high degree of uncertainty in the known history of early lpia glaciation as much of the primary stratigraphic data are limited and or unpublished future high resolution stratigraphic studies are needed to constrain the history of glaciation both spatially and temporally through the latest devonian and mississippian

time variable 3d ground displacements from high resolution synthetic aperture radar sar application to la valette landslide south french alps abstract we apply an image correlation technique to multi orbit and multi temporal high resolution hr sar data image correlation technique has the advantage of providing displacement maps in two directions e g the line of sight direction los and the azimuth direction this information derived from the two modes of data acquisition ascending and descending can be combined routinely to infer the three dimensional surface displacement field at different epochs in this study a methodology is developed to characterize the displacement pattern of the large la valette landslide south french alps using terrasar x images acquired in 2010 the results allow mapping the dynamics of different units of the la valette landslide at high spatial resolution the study demonstrates the potential of this new application of high resolution sar image correlation technique for landslide ground surface deformation monitoring

three dimensional strength reduction finite element analysis of slopes geometric effects the vast majority of slopes both natural and constructed exhibit a complex geometric configuration and three di mensional 3d state whereas slopes satisfying the assumption of plane strain infinite length are seldom encountered ex isting research mainly emphasizes the 3d dimensions and boundary effect in slope stability analysis however the effect of complex geometric ground configuration on 3d slope stability is rarely reported in this paper an elastoplastic finite element method using strength reduction techniques is used to analyze the stability of special 3d geometric slopes a typical 3d slope underlain by a weak layer with groundwater is described to validate the numerical modeling safety factor values and critical slip surface for the 3d slope furthermore a series of special 3d slopes with various geometric configurations are analyzed numerically and the effects of turning corners slope gradient turning arcs and convex and concave shaped sur face geometry on the stability and failure characteristics of slopes under various boundary conditions are discussed in detail

very high spatial resolution imagery for channel bathymetry and topography from an unmanned mapping controlled platform the increasing availability of aerial photography and satellite imagery offers new possibilities for characterizing river morphology the precision of new very high resolution vhr images allows smaller scale objects within river corridors to be studied high survey frequencies provide increased opportunities for the monitoring of river restoration following this evolution in platform technology a small radio controlled motorized vehicle flying at low altitude was used to study both channel water depth and gravel bar geometry the vhr imagery provided by this equipment allowed both channel bathymetry and a high accuracy photogrammetric digital elevation model dem to be realized using case studies from the ain and the drome rivers in france the accuracy of the results is presented and the various challenges associated with the new platform are discussed one significant issue is that due to the low elevation of the survey the coverage of a target area is usually based on several photographs which leads to variations in illumination conditions that stem from atmospheric changes the images were processed to minimize this source of error but a number of issues have yet to be resolved bathymetric models with r2 values between 0 59 and 0 90 were created in spite of the lack of channel bed homogeneity at the various sites the gravel bar was also effectively mapped and the photogrammetrically predicted dem provided a 5 10 cm pixel resolution with a vertical precision between 2 and 40 cm according to the position within the image this paper shows that despite unstable image acquisition unmanned radio controlled platforms provide significant advantages for the study of river processes offering a flexible very high resolution data source for both channel bathymetry and gravel bar topography copyright 2007 john wiley sons ltd

giant dune morphologies and dynamics in a deep continental shelf environment example of the banc du four western brittany france the aim of this paper is to improve the knowledge of spatio temporal variability of very large to giant dunes in deep tide dominated environment their growth mechanisms and dynamic evolution still remain in debate and constitute a significant scientific challenge in regard to difficulties to achieve accurate measures of migrations this motivated the realization of three recent swath bathymetry surveys across the wide dune field of the banc du four located offshore the western brittany the banc du four field is composed of more than 500 large dunes exhibiting a great diversity of morphologies ranging from 2d to 3d shapes and reaching the largest sizes of such sedimentary structure ever described wavelength over 1000 m and height over 30 m the analysis of the entire ensemble of dune parameters offers the opportunity to discuss the relative influence of forcings and the validity of the equations predicting the bedform geometry in shallow waters our results show a good height spacing power law correlation but do not strike the usual statistical regression observed in previous studies the steeper positive slope of the equation and the outstanding values of the height parameter reveal the complexity of local hydrodynamic regime interacting with bed load transport and sediment supply no clear relationship has been observed between asymmetry and size parameters water depth can not be considered as a major factor controlling the size of dunes otherwise the vertical sedimentary variation suggests the action of storm waves on dune crests and the horizontal migration rates of dunes in the eastern field of the banc du four were found to range from 3 to 20 m yr 1 such velocities were only mentioned before by van landeghem et al 2012 on deep continental shelves 70 m deep and attest of the still present morphodynamical equilibrium of the large dunes furthermore as was previously found for similar dunes in the irish sea no power law relationship between dune migration rates and dune size can be deduced similarly no strong correlation is established between migration rates and the degree of asymmetry nevertheless the dune asymmetry can be used to predict the migration direction as for dimension parameters the evolution asymmetry depends on the study area and migration rates more precisely when the crest lines of dunes form straight lines and their migration rates remain below 8 10 m yr 1 the degree of dune asymmetry increases with the migration rate this trend is reversed for the dunes with higher migration velocities and crests which are sinuous these results relativize the migratory predictions based on punctual geometrical observations

application of spatial cross correlation to detection of migration of submarine sand dunes knowledge of migration rates of bedforms provides an indirect indication of thebehavior of tidally averaged bottom currents enables optimization of hydrographic surveyfrequency and may enable calculation of bedload transport rate to measure bedformmigration rate we test the use of spatial correlation as a measurement method whichquantifies and locates a region of maximum similarity between two spatial variables forthe latter we use consecutive eight bit images of spatial gradient derived frombathymetric digital terrain models carrying out the correlation over this representation ofthe shape of the seabed rather than the bathymetric surface the digital terrain modelswere compiled from six repeat multibeam surveys of a headland associated bank nearsaint john new brunswick with a roughly 30 day interval vectors are drawn depictingthe movement of a sand dune at time t

mississippian volcanism in the south central andes new u pb shrimp zircon geochronology and whole rock geochemistry abstract in the northern extension of the famatina and the southern puna nw argentina prominent rhyolitic volcanic rocks traditionally referred to as ordovician are exposed resting on metamorphic basement and covered by thick late paleozoic siliciclastic successions we report new u pb shrimp ages from these rhyolites that show them to be of mississippian 348 342 ma age thus identifying a previously unknown volcanic event in this portion of western gondwana whole rock geochemistry and sr nd isotopic analyses suggest a crustal source for these rocks but with a juvenile input end t between 2 91 and 0 3 and tdm values between 1 09 and 1 1 ga this is different from the early paleozoic magmatism of western argentina where crustal recycling took place without any involvement of mantle material the carboniferous magmatism is compatible with an extensional environment developed along the terra australis accretionary orogen as a result of tectonic switching processes these rhyolites may be related to the coeval mississippian a type granites exposed to the east in the sierras pampeanas confirming the regional character of this magmatism

the statistics of counting clasts in rudites a review with examples from the upper palaeogene of southern california usa the relative proportions of gravel sized particles of different lithology in rudaceous sedimentary rocks are generally determined in the field by clast counting clast counts are usually carried out qualitatively in order to assess sedimentary provenance however a review of the statistical aspects of clast counting suggests that this technique also can be applied quantitatively and to investigate a variety of other objectives during basin analysis geographical and stratigraphical changes in the relative proportions of clasts can be quantified statistically and used to characterize sediment dispersal patterns in space and time respectively statistical comparisons between clast assemblages can be used as a tool to match up rock units this approach may help to constrain tectonic or suspect terrane models or to document sediment recycling both counting and sampling errors contribute to the total probable error of a clast count sampling error results from the uneven distribution of clasts in outcrop perhaps caused by selective sorting counting error arises from a count of some number less than the total number of clasts in the population sampling and counting errors can be minimized by counting in closely spaced subsets and by counting a total of at least 400 clasts respectively thus a useful procedure is to count four closely spaced subsets of 100 each and combine the results for a total of 400 point counting should not be used because differences in particle size produce biased results a better method is to count all clasts above some minimum size within a specified area of outcrop analysis of upper palaeogene non marine conglomerates composing part of the sespe formation in california using confidence intervals hypothesis testing analysis of variance ratio analysis and varietal studies demonstrates that useful statistics can be derived by counting clasts

incised valley fill interpretation for mississippian black hand sandstone appalachian basin usa implications for glacial eustasy at kinderhookian osagean tn2 tn3 boundary abstract lower mississippian strata of east central ohio are predominantly fine grained marine deposits of the cuyahoga and logan formations within these sediments is the black hand sandstone of the cuyahoga formation the black hand sandstone is a multistory crossbedded coarse grained conglomeratic sandstone the contact between the black hand sandstone and the subjacent cuyahoga formation is sharp and scoured with intraclasts of the cuyahoga formation incorporated into the basal black hand sandstone the black hand sandstone was previously thought to represent a distributary channel deposit however the combination of lithofacies and architectural elements indicates deposition in a braided stream setting the cuyahoga formation was deposited in a shallow marine setting the erosional basal contact of the black hand sandstone and the juxtaposition of fluvial and marine sediments suggests a sequence boundary the geographic distribution of the black hand sandstone combined with the evidence for a sequence boundary suggests deposition in an incised valley the age of the black hand sandstone is key to inferring the causes of valley incision the black hand sandstone is nearly devoid of body fossils necessitating a biostratigraphic analysis of the surrounding cuyahoga and logan formations analysis indicates the logan formation is early osagean age data from the cuyahoga formation suggest a kinderhookian age with a possible transition to the osagean in the uppermost cuyahoga formation this constrains the age of the black hand sandstone to the transition at the kinderhookian osagean boundary recent reports indicate late kinderhookian tournaisian tn2 gondwanan glaciation based upon tillites and sharp excursions in stable isotope curves a glacio eustatic fall in sea level is inferred to have caused incision of the cuyahoga formation followed by deposition of the black hand sandstone and logan formation during the subsequent sea level rise the associated unconformity correlates to the sequence boundary at the kinderhookian osagean boundary in the stratotype area of north america and the correlative tn2 tn3 boundary worldwide supporting the hypothesis of a global eustatic event at this time

estimating carboniferous sea level fluctuations from gondwanan ice extent the magnitude of carboniferous sea level fluctuations is not well known but the estimates are important for constraining cyclothem models in this paper we apply area volume relations developed for quaternary ice sheets to estimate the glacio eustatic component of sea level fluctuations in the carboniferous utilizing the best estimate of gondwanan ice area at the time of its greatest extent we arrive at a figure of 60 15 m for the isostasy corrected glacio eustatic component this value is nearer the lower limit of sea level estimates for cyclothem fluctuations from other sources

the level of the grimsvotn subglacial lake vatnajokull iceland monitored with spot5 images abstract we describe the vertical displacement field of an ice shelf floating on a subglacial lake grimsvotn located underneath the vatnajokull ice cap iceland the uplift is measured using the correlation of two satellite optical spot5 images acquired 5 days apart with similar non vertical incidence angles this is the first time correlation of optical images has been used to measure vertical displacements our technique is suitable for mapping short term elevation changes of glaciers if the surface features are preserved vertical displacements can be measured every 25 m with an accuracy of about 0 5 m the uplift map of grimsvotn shows that 10 9 1 km 2 of ice was floating between 11 and 16 august 2004 the ice shelf rose by 1 7 0 6 m indicating that the volume of liquid water in the lake increased by 0 018 0 007 km 3 our field observations show that surface melting due to meteorological processes contributed 70 of the accumulated water hence the rest originated from ice melted by the subglacial geothermal activity the power required to melt 0 005 km 3 water equivalent of basal ice in 5 days is 4000 mw the applicability of the technique can be extended to volcanology and seismology and even landslides or subsidence when finer resolution optical images become available applied to two pairs of images it could solve for the 3 dimensional displacements of the earth s surface

kinematics of active earthflows revealed by digital image correlation and dem subtraction techniques applied to multi temporal lidar data earthflow type landslides are persistent natural hazards having deep socio economic and environmental consequences they have significantly contributed to the geomorphic evolution of mountainous slopes in europe since the late glacial an understanding of their complex kinematics is crucial to better constrain the processes governing their occurrence and mobility in this work we explored the possibility to quantify displacement vectors on a spatially distributed basis and to quantify volumetric transfer at the slope scale with regard to a large flow type landslide located in the northern apennines of italy for this purpose we applied digital image correlation dic and digital elevation model differencing demod techniques to multi temporal airborne lidar surveys of 2006 2007 and 2009 the dic was applied to greyscale slope gradient maps retrieved after precise co registration of lidar surveys thereby movement patterns over various sectors of the landslide were reconstructed and quantified most notably up to 20 m in the head zone up to 51 m in the lower main track and up to about 27 m at the landslide toe the demod analysis revealed significant mass transfer from the source to the tracks and toe zone with the upper flow tracks acting as temporal storage of large amounts of material the mass balance indicated that significant amounts of advancing landslide debris were eroded by a local stream an integrated analysis of demod and dic results allowed for a discussion of governing processes such as the transition from slide to flow the influence of underlying topography on earthflow mobility and the role of undrained loading as a mechanism of toe zone reactivation in conclusion the successful application of dic and demod to the case study underlines the added value of high resolution dems in the analysis of earthflow kinematics toward a better understanding of their role in the geomorphic evolution of slopes copyright 2012 john wiley sons ltd

evidence of glacial abrasion in the calingasta uspallata and western paganzo basins mid carboniferous of western argentina abstract evidence of glacial abrasion is present in the basal part of the carboniferous section of the calingasta uspallata and paganzo western argentina where subglacial and proximal glacial marine diamictites with pebbly dropstone shales constitute the dominant facies association intraformational striated pavements are exposed in the hoyada verde and leoncito formations of the calingasta uspallata basin marine invertebrate fossils levispustula zone in associated shales indicate a mid carboniferous age for both units a single layer striated boulder pavement is superbly exposed in the hoyada verde formation local a axis clast imbrication in the underlying bouldery diamictite and strong parallel striae on the flattened upper surfaces of boulders indicate a subglacial origin for the pavement paleo ice flow directions have an nne ssw strike the leoncito intraformational pavement is shaped on bioturbated fine grained sandstones with plant remains glacial striations are straight and parallel with subcircular cross sections dome like features are present in the surface which is covered in turn by a sandy bouldery diamictite four striated surfaces are present in the western paganzo basin three of them pavements at the san juan river valley loma de los piojos and agua hedionda are developed on basement rocks they contain parallel to subparallel striations nailhead striations crescentic gouges impact marks and furrows the pavements are overlain by thin up to 1 5 m laterally discontinuous diamictite beds with striated clasts some of them bullet shaped paleo ice flow directions are n ne directed an intraformational pavement is also present at the san juan river valley section it is carved on the top of the basal diamictite and exhibits furrows probably caused by subglacial soft sediment grooving the dispersion of paleo ice flow directions in the calingasta uspallata and paganzo basins indicates i regional slopes toward the north into a brackish water embayment and northwest into the open marine conditions ii glacial erosion by ice grounded below sea level and confined to the margins of the basins

landslide velocity thickness and rheology from remote sensing la clapiere landslide france our analysis of la clapiere an 1 km 2 bedrock landslide reveals a concave up failure surface with considerable roughness over length scales of tens of meters calibrating the thickness model with independent local thickness measurements we find a maximum thickness of 163 m and a rheology consistent with distributed deformation of the highly fractured landslide material rather than sliding of an intact rigid block the technique is generally applicable to any mass movements that can be monitored by active or historic remote sensing citation booth a m m p lamb j p avouac and c delacourt 2013 landslide velocity thickness and rheology from remote sensing la clapiere landslide france geophys res lett 40 4 299 4304 doi 10 1002 grl 50828

use of digital photogrammetry for the study of unstable slopes in urban areas case study of the el biar landslide algiers abstract recent developments in remote sensing techniques provide powerful tools for geomorphological studies the geometric and kinematic characterization of landslides is a key factor in understanding the mechanisms of movement the purpose of this publication is to show the potential of digital photogrammetry in the spatiotemporal study of landslides in urban areas the case study focuses on the landslide of el biar in algiers comparison of digital elevation models generated following an established methodology shows the morphological evolution of the site orthophotos are used to measure surface displacements the analysis of horizontal displacements between 1995 and 2007 shows that the landslide of el biar can be divided into two zones a peripheral zone moving at an average speed of about 5 cm per year and a central zone moving at an average speed of about 10 cm per year comparing the results with those obtained by traditional survey methods shows a remarkable consistency thus validating the techniques used this study demonstrates that digital photogrammetry when combined with geological and geotechnical data can improve the characterization and understanding of landslide mechanisms and thus help defining mitigation solutions

reassessment of mid carboniferous glacial extent in southwestern gondwana rio blanco basin argentina inferred from paleo mass transport of diamictites abstract late paleozoic glacial diamictites occur in many localities in western argentina indicating that the region was strongly affected by glaciation during the mid carboniferous late serpukhovian early bashkirian in most instances these diamictites are found in steeply walled paleovalley settings in the andean precordillera this study presents new data from a locality north of the precordillera that suggests an additional distinct volume of ice existed in the region during the carboniferous the glacigenic diamictites in the rio blanco basin were ultimately emplaced as gravity flows precluding inferences of paleo ice volume fold nose orientation and soft sediment groove orientations within the diamictites indicate that the deposits were emplaced from north to south suggesting that glacial ice was most likely not sourced from the proto precordillera at this locality requiring the need for another ice center to the north of the basin diamictite facies indicates that the sediment was initially supplied to the study area by a warm based glacier

two new methods of paleocurrent determination from trough cross stratification abstract trough cross stratification is the most abundant accurate and efficient palcocurrent direction indicator in fluvial deposits however exposures in which trough axes can be measured are rare two new methods are presented for the determination of paleocurrent directions from the more common exposure types namely the use of three dimensional exposures of oblique cuts through individual trough limbs and two dimensional exposures of sets of trough cross strata three dimensional exposures of trough limbs can be measured and treated statistically on a stereographic plot to determine the average trough axis orientation in two dimensional exposures characteristic asymmetry of the basal scour surface and truncation of foreset laminae can aid in estimation within about 25 of pal ocurrent direction

reconstructing the evolution of a deep seated rockslide marzell and its response to glacial retreat based on historic and remote sensing data abstract in this study a combination of different topographic data from historic topographic maps and remote sensing is used to reconstruct and monitor the behaviour of the high alpine ice contact rockslide system marzell and its response to glacial debuttressing in the eastern alps topographic data from archives historical topographic maps national glacier inventories aerial images orthoimages and als data and data from monitoring campaigns geodetic measurements terrestrial laser scanning and uav imaging campaigns are processed to georeferenced images and or elevation data respectively the data from different data sources is compiled and analysed with the aim to i reconstruct the extent thickness and volume changes of the glacier since 1893 and ii to analyse the rockslide deformation evolution by extracting information about the displacement direction dip angle velocity and partial failure of rockslide slabs since 1951 the rockslide is compound of different rockslide slabs which move downwards as rigid blocks along basal shear zones the analyses and interpretation of the data suggest a rotational type of rockslide failure mechanisms the rockslide activity correlates with the ice volume loss at the adjacent part of the glacier in the period between 1971 and 1997 the annual average rockslide activity was about 0 05 m a and the annual average ice thickness loss was 0 1 m a since the end of the last century the annual average ice thickness loss increased dramatically to 5 m a in that period the rockslide activity accelerated the highest rockslide activity up to 1 5 m a was observed in the 2000s when half of the slope toe was exposed because of glacier retreat since 2010 a deceleration of the rockslide can be observed in the vicinity of the rockslide the glacier almost disappeared and lost 99 88 of its ice volume between 1893 and 2014 the geomorphological and geological information gathered about the rockslide evolution and the glacier retreat form the base for further rockslide analyses and allow to study and model the influence from glacial debuttressing

use of sentinel 2 images for the detection of precursory motions before landslide failures abstract the sentinel 2 optical satellites provide a global coverage of land surfaces with a 5 day revisit time at the equator we investigate the ability of these freely available optical images to detect precursory motions before rapid landslides a 9 month time series of displacement is derived from sentinel 2 data over a major landslide in the french alps which exhibited a sudden reactivation in june 2016 this analysis reveals a 7 month period of low activity 1 m followed by a sudden acceleration of 3 2 1 2 m in 3 days before the failure of a mass of about 2 to 3 6 106 m3 the location of this precursory motion is consistent with that of the slow motions occurring since 2001 about 1 m year as revealed by aerial photographs and lidar analysis this change in activity over a very short period of time days emphasizes the value of the frequent revisit time of sentinel 2 despite its medium resolution of 10 m we finally simulate the ability of sentinel 2 for detecting these precursory patterns before a rapid landslide occurs based on typical voight s laws for creeping materials characterized by a power law exponent based on this analysis and on global cloud cover maps we compute the probability to detect pre failure motions of landslides using the sentinel 2 constellation this probability is highly heterogeneous at the global scale affected by the revisit time of the satellite and the cloud cover however the main factors controlling this detection ability are the properties of the landslide itself its size and the parameter with almost 100 of detection probability for 1 3 and 0 for 1 8 despite all these limitations probability to detect a motion before a landslide failure often reaches 50 for classical landslide parameters these results open new perspectives for the early warning of large landslide motion from global and open source remote sensing data

low cost volcano deformation monitoring optical strain measurement and application to mount st helens data summary this paper describes an innovative method of volcano deformation measurements applied to camera images taken from the 2004 2008 eruption period at mount st helens dome growth was thought to be characterized by sustained near linear rates of a solid dacite plug through spatial digital image correlation dic analysis of the camera images new evidences arise that the deformation and strain rate of the spine was more complex dic yielded cumulative and incremental displacements strain and shear planes at decimetre resolution it was found that dome extrusion rates are highly non linear decelerating prior to partial collapse followed by a pronounced dome extrusion increase and direction change associated processes have been identified through dic such as shallow landslides and reworking of talus apron material the work highlights the strengths of camera strain monitoring and illustrates that dome growth and collapse is a very dynamic process complexly interplaying with the surrounding

direct measurement of ocean waves velocity field from a single spot 5 dataset we present a method based on space borne optical imagery from the spot5 satellite to directly measure the phase velocity fields of ocean waves the panchromatic and multispectral scenes acquired by spot5 the same day on the same area are not strictly superimposable due to the different locations of the ccds charged coupled device in the focal plane of the instrument in this manuscript we propose a method that exploits the temporal lag that exists between the panchromatic and multispectral scenes to measure the ocean wave velocity fields we firstly discuss the principle and the methodology then we apply it offshore la reunion island finally we compare and discuss the results against a swell propagation model our method is proven reliable and can be immediately extended to other push broom sensors

glaciomarine sequence stratigraphy in the mississippian rio blanco basin argentina southwestern gondwana basin analysis and palaeoclimatic implications for the late paleozoic ice age during the tournaisian the late palaeozoic ice age lpia has been well recorded in the uppermost mississippian pennsylvanian of gondwana nevertheless little is known about the temporal and geographic dynamics particularly during the early mississippian we report on exceptional tournaisian glaciomarine strati graphic sections from central argentina rio blanco basin encompassing 1400 metres these succes sions contain conspicuous glacigenic strata with age constraints provided by palaeontological data and u pb detrital zircon age spectra a variety of marine glaciomarine and fan deltaic environments indicate relative sea level variations mainly associated with tectonism and repetitive cycles of glacial activity provenance analysis indicates a source from the sierras pampeanas basement located to the east fifteen sequences were grouped into three depositional models 1 transgressive systems tracts tst to high stand systems tracts hst sequences unaffected by glacial ice 2 lowstand systems tracts lst to tst and then to hst with glacial in uence and 3 non glacial falling stage systems tract fsst to tst and hst the glacial evidence indicates that the oldest mississippian glacial stage of the lpia in southwestern gondwana is constrained to the middle tournaisian in contrast with previous descriptions of gondwanan coeval glacial records our sequence analysis confirms complex hierarchical climate varia bility rather than a single episode of ice advance and retreat supplementary material https doi org 10 6084 m9 figshare c 5011424

late paleozoic paleoclimatology of central west argentina abstract based on sedimentologic and paleontological characteristics present in the sedimentary record of the calingasta uspallata and paganzo basins a model of paleoclimatic evolution for the late paleozoic of central west argentina is proposed additional evidence is also provided by data from other basins of southern san rafael and tepuel basins and northern tarija basin west argentina five paleoclimatic stages have been defined paleoclimatic stage i tournalism visean early carboniferous is characterized by temperature and humid preglacial conditions as evidencedin the el raton and maliman formations calingasta uspallata basin plant remains of archeosigillaria and lepidodendropsis zone are present in both units the paleoclimatic stage ii namurian early westphalian middle carboniferous comprises widespread glacial deposits including glaciomarine sequence in the westernmost basins calingasta uspallata western paganzo san rafael and tepuel and terrestrial tillites and glaciolacustrine fine clastics in some areas of the paganzo basin fossils of the levipustula fauna are distinctive in the glaciomarine deposits of this stage and in the overlying postglacial fine clastics of the basal portion of stage iii substage iiia the paleoclimatic stage iii of middle carboniferous late westphalian age corresponds to postglacial transgressions that flooded the previously glaciated shelves in the calingasta uspallata and tepuel basins terminal glaciolacustrine deposits substage iiia indicate of the demise of glacial conditions and coal measures of fluvial affinity in the paganzo basin substage iiib probably this postglacial stage was characterized by high humidity and moderate temperatures this stage is paleobiologi defined by a floral assemblage known as nbg nothorhacopteris botrychiopsis and ginkgophyllum the paleoclimatic stage iv late carboniferous stephanian early permian corresponds to a time interval characterized by seasonally dry climates and a progressive amelioration in humidity clear evidence of these climatic conditions is present in several localities in the paganzo basin the first astherothecae and glossopteris leaves are found finally paleoclimatic stage v middle late permian is dominated by red beds thick eolian sequences and saline lake facies deposited under arid to semi arid conditions coeval volcanism derived from the west is expressed by interbedded tuffs and agglomerates calingasta uspallata paganzo and san rafael basins

seventeen years of the la clapiere landslide evolution analysed from ortho rectified aerial photographs we present a new method of digital elevation model dem calculation from aerial photographs and apply this method to the la clapiere landslide in the mercantour massif in eastern france the method uses new techniques of image correlation and of restitution of camera parameters the calculated dems are used to ortho rectify three aerial photographs acquired between 1983 and 1999 measurements made from these ortho rectified images show that the average velocity of the landslide was of 1 7 cm day with the rate of the headscarp retreat of 4 1 cm day and the toe of the landslide advancing at 1 7 cm day between 1983 and 1999 within the landslide the velocity field is are relatively homogeneous although their directions are locally heterogeneous scree slopes and scarps develop in an heterogeneous way within the landslide because the headscarp moves faster than the front of the landslide material spreads laterally at the scree slopes and or is eroded at the front of the landslide by the river and or is accumulated within the landslide on a low slope area located above a competent bar called igliere bar d 2002 elsevier science b v all rights reserved

facies and petrophysical signature of the tournaisian visean lower carboniferous sea level cycle in carbonate ramp to basinal settings of the wales brabant massif british isles we studied the relationships between stratigraphic distribution of outcrop spectral gamma ray magnetic susceptibility and carbonate facies stacking patterns across the regionally significant transgressive regressive cycle at the tournaisian visean boundary tn v early carboniferous in southern great britain and ireland south wales north staffordshire and dublin basin the tn v boundary coincides with a prominent climatic pulse connected with the late paleozoic glaciation of gondwana the aim was to correlate the gamma ray and magnetic susceptibility log patterns in carbonate ramp and basin settings and discuss the global regional nature and magnitude of this transgressive regressive cycle a robust ramp to basin correlation was produced based on the log patterns facies stacking patterns and foraminifer biostratigraphy the concentrations of k and th the clay gamma ray values and partly magnetic susceptibility are dependent on facies and show systematic changes along the inferred bathymetric profile from inner ramp to outer ramp and basin a model of carbonate productivity driven dilution of fine grained siliciclastics in caco3 as the major control on the petrophysical patterns is discussed the cleaning up and cleaning down petrophysical trends are related to down dip and up dip shifts of the carbonate factory with changing relative sea level in middle to outer ramp and basin settings this generates petrophysical trends just opposite to paleozoic carbonate shelves where peaks in magnetic susceptibility are known to be associated with peak regressions a distinct late tournaisian to early visean regressive to transgressive cycle with a prominent sequence boundary located close to the tn v stage boundary can be seen in the sections glacioeustatic origin of the sequence boundary is inferred from its correlation with tn v boundary sections from europe carbon isotope data from south china and the glacial deposits in the southern hemisphere mentioned by previous authors

glacimarine processes at grounding line fans and their growth to ice contact deltas abstract grounding line fans originate from subglacial and basal stream tunnels at grounding lines of glaciers terminating in a marine environment during melt seasons discharge forms a turbulent jet beyond the efflux over the initial zone of flow establishment in the jet it may remain in contact with the sea floor for up to 13 4 d d tunnel diameter along a runout distance if velocity is constant plug flow in this zone deposits marine outwash sediment commonly having chaotic texture and graded and welded contacts texture may vary rapidly because of discharge pulses and the jet may move laterally to produce sheet or cut and fill geometries imbricate gravel is deposited near the efflux then farther out are sheet or weakly channelized finer grained gravels and sands in some instances a migrating barchanoid bar forms at the detachment zone and forms large scale trough cross beds beyond the detachment zone the turbulent jet becomes vertical and sediment cascades from it in a veil this sediment is added to by flows from continuous failures of bed load sediment in the detachment zone resulting deposits are interstratified sediment gravity flows and thick coarse end members of cyclopsams the jet changes to a plume when inertial forces become less than buoyancy forces turbulent vorticies within the jet can re entrain particles into a buoyant plume the plume remains vertical although continuously spreading until reaching neutral buoyancy fan depocentres have been observed to accumulate at over 10 6 m 3 a 1 in temperate glacial areas eventually at quasi stable grounding lines fans may aggrade to sea level to form ice contact deltas at incipient deltas when the delta plain is intertidal coarse sediment is redistributed to the prodelta with each tidal cycle intense prodelta rhythmites mark the transition of a fan into a delta

recognition of interfluve sequence boundaries integrating paleopedology and sequence stratigraphy in shallow marine and coastal plain strata sequence boundaries are easily recognized at the base of incised valley fills between valleys however it is more difficult to recognize sequence boundaries where they are expressed as interfluve paleosols we suggest that interfluve paleosols can be most reliably identified using a combination of 1 stratigraphic position 2 field observations such as thickness structure color and degree of rooting and 3 micromorphological features such as bioturbation fabric clay coatings ferruginous features and siderite and barite only micromorphology permits recognition of temporal changes in drainage surface stability and protracted pauses in sedimentation that typify these surfaces this three part approach has been successfully employed to identify interfluve sequence bounding paleosols in the cenomanian dunvegan formation in alberta and british columbia canada

acquisition of water chemistry in a mobile fissured basement massif its role in the hydrogeological knowledge of the la clapiere landslide mercantour massif southern alps france abstract groundwater flowpaths of the la clapiere landslide are studied by chemical and isotopic water analysis and modeling of the landslide springs in our case it appears that sulfate can be taken as a chemical tracer of the different flowpaths on the gneissic slope of la clapiere geochemical modeling explains sulfate concentrations from 0 to 130 mg l by dissolution of sulfurous minerals present in the gneisses such a variability of the concentrations measured in the springs is due to different infiltration paths direct paths through the basement so 4 2 10 60 mg l or indirect path through superficial deposits like screes or fluvio glacial terrains which cover the basement so 4 2 60 130 mg l the high concentrations 600 800 mg l cannot be explained by thermodynamic geochemical simulations and they reveal triassic gypsum dissolution hidden under the studied slope so two main flowpaths are differentiated in the la clapiere landslide 1 flow through low permeable triassic deposits pinched under the foot of the landslide 2 flow through a more permeable fissured basement with different flow paths and consequently with different transit times due to the anisotropic nature of the top and the central part of the landslide

models of glaciomarine sedimentation and their application to the interpretation of ancient glacial sequences abstract this paper argues that glaciomarine environments can be regarded as special glacially influenced types of continental margin environments e g continental shelf slope rise and basin plain knowledge of the stratigraphic architecture and typical sedimentary sequences of non glacial margins is becoming well known but remains limited for those that have been glacially modified the principal influences on sedimentation in these environments relate to the glacial sediment input controlled by relief of basin margin glacier thermal regime and ice flow dynamics and depositional environments influence of traction currents substrate relief and proximity to nearby ice margins typical ranges of sedimentation rates can be established for glacially influenced continental margin environments and these may provide a framework for ancient sequences starvation of sediment supply to glacially influenced continental margins is common the nature of sub ice shelf sedimentation a model that has been applied to many ancient glacial sequences is critically reviewed the significance of such sedimentation in the rock record has probably been exaggerated because of oversimplistic interpretations of diamictite sequences existing process models of glaciomarine sedimentation derived from study of modern environments are sometimes difficult to employ in investigation of ancient sedimentary sequences because simple lithofacies criteria and typical vertical profiles are not available to aid in interpretation in addition compositional data emphasized by many workers for distinguishing glaciomarine from continental glacial diamict ite s frequently fingerprint sediment source and not mode of deposition the importance of facies analysis methods for isolating depositional environments is illustrated by three examples of ancient glaciomarine sequences these are the early proterozoic gowganda formation 2 3 ga of northern ontario canada the late proterozoic port askaig formation 670 ma of scotland and ireland and the late cenozoic yakataga formation 20 ma to recent of the gulf of alaska these examples illustrate the significance of detailed genetic studies of ancient glacial rocks in the interpretation of palaeogeographic and tectonic settings diamictite units in ancient glaciomarine sequences cannot be easily interpreted in terms of climatic or ice advance retreat cycles because of the varied controls on diamict accumulation and diamictite preservation in marine basins

non catastrophic landslides induced by the mw 7 6 chi chi earthquake in central taiwan as revealed by piv analysis abstract the chi chi earthquake occurred in the western foothills of central taiwan which triggered coseismic and catastrophic chiufengershan dip slope landslides tsaoling rockslides and surface stripping of the jiujiufeng area after a few days of the chi chi event the hongtsaiping area in central taiwan was reported to have several meters of slide in a small scale area the reported landslides are dissimilar to the catastrophic events to better understand the characteristics of such non catastrophic and unobvious landslide we try to characterize in detail the sliding directions their magnitudes and region of the landslide we analyzed three orthorectified aerial photographs of the hongtsaiping area which were taken in 1998 06 13 1999 11 18 and 2002 10 26 using the particle image velocimetry piv technique through the method we correlated the image pixels of the two aerial photographs in order to derive the displacement vector field the results of the piv analysis have helped us not only find the areas where sliding had happened but also evaluate the azimuth and magnitudes of the sliding event the piv analysis in the hongtsaiping area covers a dimension of about 3228 2448 pixels in an area of about 1 2 km2 our results show that the maximum horizontal displacement of the landslide is about 24 m towards nw in the study area this unobvious but wide coverage landslide may need further investigation in mechanisms combining with available or new geological data

the tice event perturbation of carbon nitrogen cycles during the mid tournaisian early carboniferous greenhouse icehouse transition abstract carbonate carbon 13ccarb and bulk nitrogen 15n isotopic variation during the mid tournaisian was analyzed in the malanbian and long an sections of south china their c isotope profiles document a large positive excursion herein termed the mid tournaisian carbon isotope excursion tice during the siphonodella isosticha conodont zone although its magnitude differed between the two sections 6 at malanbian versus 3 at long an the tice event coincided with sedimentologic and oxygen isotopic evidence of climatic cooling and glaciation during the mid tournaisian it was probably triggered by an increase in organic carbon burial rates linked to changes in global ocean circulation the study sections also document a large positive shift in 15n from 1 7 to 4 2 at malanbian and from 1 5 to 3 8 at long an the n isotope shift shows no termination within the study sections and is likely to mark the onset of an extended interval of 15n enriched marine nitrate that lasted for the duration of the late paleozoic ice age its initiation coincided with tice and thus may have been linked to ocean circulation changes that resulted in intensified upwelling and an increase in water column denitrification the continuation of the n isotope shift over millions of years may have been linked to glacio eustatic fall and a long term shift in the locus of denitrification from continental shelf sediments to continent margin oxygen minimum zones the tice event thus marks the onset of sustained continental glaciation during the late paleozoic ice age

coseismic horizontal offsets and fault trace mapping using phase correlation of irs satellite images the 1999 izmit turkey earthquake on august 17 1999 a strong earthquake mw 7 4 occurred along the western sector of the north anatolian fault system in turkey the epicenter was located near the city of izmit 50 km east of istanbul previous works determined the coseismic surface displacements by satellite synthetic aperture radar sar interferometry insar and satellite optical image correlation in 1999 the highest spatial resolution orbiting camera was the panchromatic sensor pan a 5 8 m pixel sensor spot 2 was a 10 m pixel sensor onboard the indian remote sensing irs satellite we propose to apply a new phase correlation method to pan images to study the coseismic rupture due to the izmit earthquake the phase correlation method does not need phase unwrapping and was proved to be robust under a wide variety of circumstances image correlometry deals with the quantification of the subpixel offsets over the whole image allowing displacement measurement with an accuracy that is proportional to the pixel size we measured the near field deformations exploiting two geometrically corrected irs images with similar look angles a quality check of the derived offset map was performed by comparison with gps benchmarks and spot offsets the results show that irs pan images can be correlated to derive coseismic slip offsets due to a large earthquake and to map its fault trace

controls on synorogenic alluvial fan architecture beartooth conglomerate palaeocene wyoming and montana late palaeocene uplift of the beartooth range in northwestern wyoming and southwestern montana generated the beartooth conglomerate along the eastern and northeastern flanks of the range systematic unroofing sequences and intraformational unconformities folds and faults in the conglomerate attest to deposition during uplift along the eastern flank at least three ancient alluvial fan systems and a braidplain system can be distinguished on the bases of petrofacies and lithofacies the two southern fans consist of 700 m of sedimentary clast conglomerate and subordinate sandstone dominated by hyperconcentratedflow and stream flow facies the next fan to the north is dominated by plutonic and metamorphic clasts and contains abundant mud matrix supported debris flow facies as well as stream flow facies the northernmost depositional system consists of arkosic channellized fluvial conglomerate and sandstone overbank mudstone and crevasse splay sandstone units palaeocurrent data indicate eastward dispersal away from the beartooth range outstanding exposure of the beartooth conglomerate allows facies to be mapped on lateral photographic mosaics a seven fold hierarchy of bounding surfaces and enclosed lithosomes exists in the beartooth conglomerate first through fourth order surfaces are analogous to first through fourth order surfaces that recently have been documented in sandy fluvial facies with one exception sediment gravity flows are bounded by first order surfaces fifth order surfaces are either erosional e g lateral migration of fanhead trench or accretionary e g aggradation of fan surface during backfilling of trench and construction of lobes on lower fan during entrenchment on upper fan some fifth order surfaces coincide with intraformational angular unconformities and are thus the result of long term fanhead entrenchment following uplift of the upper part of the fan sixth order surfaces bound individual fan packages that are several hundred metres thick and 10 km2 in area the enclosed sixth order lithosomes are distinguishable in terms of petrofacies and lithofacies a single seventh order surface bounds the entire beartooth conglomerate lower order lithosomes are produced by intrinsic processes of fan construction fifth order lithosomes can be attributed to both extrinsic and intrinsic controls sixth and seventh order lithosomes are generated by extrinsic controls

two examples of the use of sar interferometry on displacement fields of small spatial extent interferometric combination of pairs of sar images acquired by the european ers 1 satellite maps deformation fields associated with two phenomena both of small spatial extension and located in se france the one is rapid terrain deformation caused by a landslide near the city of saint etienne de tinee and the other is slower subsidence caused by underground coal mining near gardanne unlike interferometric measurement of wide field deformation atmospheric propagation heterogeneity is not an accuracy limiting factor although the radar data confirm prior knowledge concerning the landslide such an application of sar interferometry appears difficult under normal conditions of observation using current spaceborne radar systems the study of soil subsidence however can be generalized and improves prior knowledge of the displacement field which has here been modeled assuming elastic deformation in a half space from several sources the two examples help to understand the limits of the interferometric technique

surface displacements and surface age estimates for creeping slope landforms in northern and eastern iceland using digital photogrammetry abstract in this study three areas of different active coarse debris slope processes are investigated in northern and eastern iceland surface displacement of some glacier derived rock glaciers and a debris covered glacier in the holar area a moving debris accumulation close to siglufjor ur and a debris layer in sey isfjor ur are measured the displacement fields are obtained by cross correlation matching of multi temporal orthophotos orthophotos are generated using a z i imaging digital photogrammetric workstation and various series of air photos from 1964 to 1994 cross correlation matching is done with the cias software the results are analyzed and used for rough surface age estimates in addition type and cause of movement are discussed the velocity of the debris covered glacier and the rock glaciers in the holar area averages from 0 14 to 0 67 m a 1 the debris accumulation at almenningsnof close to siglufjor ur shows an average displacement of 0 19 m a 1 with a maximum value of 0 84 m a 1 the displacements at almenningsnof agree well with displacements surveyed by gps by the icelandic road authorities the measured velocities in sey isfjor ur although using air photos taken 30 years apart turned out not to be significant but the homogenous direction of the displacement vectors suggests that the debris is currently creeping based on the surface age results all the landforms in holar are suggested to have developed during the late holocene cooling period with ages from around 1500 and 3000 to around 5000 years for the different landforms these surface age estimates coincide with data from moraine datings nearby and holocene climatic development in the north atlantic region

sedimentary facies and depositional architecture of ice contact glaciomarine systems abstract the characteristics of ice contact glaciomarine systems are reviewed based on a range of weichselian and holocene examples from the fjordal basins in norway and svalbard these depositional systems occur as large morphological ridges end moraines including push moraines which are coarse grained and show large scale foreset bedding the paper addresses some of the major problems with regard to the recognition classification and stratigraphic analysis of these systems the ice proximal glaciomarine systems are classified here into three categories 1 ice contact submarine fans 2 ice contact deltas and 3 glaciofluvial deltas this classification integrates morphological and sedimentological criteria and renders these glaciomarine systems not only easier to recognize in the stratigraphic record but also possible to compare with common non glacial deltaic systems the emphasis is on the criteria for the recognition of the ice contact glaciomarine systems i e ice contact fans and ice contact deltas and their discrimination from common gilbert type deltas and fan deltas the review further focuses on ice contact glaciomarine systems as highly sensitive recorders of glacier dynamics and climatic fluctuations it is shown that both the periods of ice front stability and changes in the ice front position as well as the magnitude and rate of those changes are all recorded in the ice contact depositional system the sedimentary record further reflects glacio isostatic sea level changes and local palaeogeography a new conceptual model is suggested which places these ice contact glaciomarine systems in a dynamic stratigraphic context the model integrates sedimentary facies and their depositional architecture in an allostratigraphic framework and is meant to be a guide for the analysis of the sedimentary record of ice contact systems

kinematics of a giant slow moving landslide in northwest china constraints from high resolution remote sensing imagery and gps monitoring abstract slow moving landslides generally are long lived and characterized by continuous movement with some fluctuation in sliding rate following changes of environmental factors such as rainfall and earthquake analysis on kinematics of this type of landslide is essential for understanding its mechanism and identifying causal factors controlling its movement behavior this paper presents a study on kinematics of a giant slow moving landslide in northwest china called the xieliupo landslide which is about 72 10 6 m 3 in volume and has been slowly moving for more than 100 years this study is conducted using archival high resolution remote sensing images from multi sources over a period about 43 years and the data from 15 month gps monitoring six sets of multi source remote sensing images in 1969 1971 2004 2008 2010 and 2012 with spatial resolution higher than 2 5 m were used and gps monitoring data were recorded from september 2012 to december 2013 obvious geomorphologic changes identified from the images in 1971 and 2004 confirm that this landslide did move slowly in the past quantitative analysis reveals that movement of the landslide was persistent and behaved in a block by block mode with the greatest and the least velocities in its middle and lower parts respectively distance measurement between the homologous point pairs on the orthorectified images in 2005 2010 and 2012 indicates that annual ground displacement of the landslide ranged from 0 52 m to 6 54 m in the seven years gps monitoring data shows that the landslide ground displacement in the 15 months varied from 0 49 m to 2 91 m and annually between 0 39 m and 2 33 m with a rather uniform movement pattern as identified using the remote sensing images gps monitoring results also reveal that the landslide movement is intermittent inter annually it is further discussed that movement behavior of the landslide is largely controlled by its topography with great influence of the active fault along its left hand flank and river erosion at its toe rainfall may affect inter annual movement behavior of the landslide

glacial isostatic adjustment and the anomalous tide gauge record of eastern north america sea level variations as recorded by the global network of tide gauges represent a rich data set for studying a wide range of natural and anthropogenic phenomena such as the sea level rise induced by possible global warming for this purpose long term sea level trends must be corrected for the contaminating effects of continuing glacial isostatic adjustment1 5 gia the numerical correction procedure has for sites on the east coast of north america yielded a set of highly anomalous sea level rates characterized by systematic geographical trends2 4 5 we demonstrate that these trends are a consequence of inadequacies in the previous standard numerical prediction for gia in particular we find that the well known trends in the gia corrected tide gauge rates are eliminated if the lower mantle viscosity of the earth model used in the gia prediction is increased this result obviates the need to explain the anomalous trend as a manifestation of gulf stream ocean circulation4 or neotectonic processes2

late devonian glacial deposits from the eastern united states signal an end of the mid paleozoic warm period abstract a late devonian polymictic diamictite extends for more than 400 km from northeastern pennsylvania across western maryland and into east central west virginia the matrix supported unbedded locally sheared diamictite contains subangular to rounded clasts up to 2 m in diameter the mostly rounded clasts are both locally derived and exotic some exhibit striations faceting and polish the diamictite commonly is overlain by laminated siltstone mudstone facies associations laminites the laminites contain isolated clasts ranging in size from sand and pebbles to boulders some of which are striated the diamictite laminite sequence is capped by massive coarse grained pebbly sandstone that is trough cross bedded a stratigraphic change from red calcic paleo vertisols in strata below the diamictite to non calcic paleo spodosols and coal beds at and above the diamictite interval suggests that the climate became much wetter during deposition of the diamictite the diamictite deposit is contemporaneous with regressive facies that reflect fluvial incision during the late devonian of the appalachian basin these deposits record a late devonian episode of climatic cooling so extreme that it produced glaciation in the appalachian basin evidence for this episode of climatic cooling is preserved as the interpreted glacial deposits of diamictite overlain by glaciolacustrine varves containing dropstones and capped by sandstone interpreted as braided stream outwash the appalachian glacigenic deposits are contemporaneous with glacial deposits in south america and suggest that late devonian climatic cooling was global this period of dramatic global cooling may represent the end of the mid paleozoic warm interval that began in the middle silurian

the record of tidal cycles in mixed silici bioclastic deposits examples from small plio pleistocene peripheral basins of the microtidal central mediterranean sea the pliocene pleistocene peripheral marine basins of the mediterranean sea in southern italy from basilicata and western calabria to northern and eastern sicily represent tectonically formed coastal embayments and narrow straits here units of cross stratified mixed silici bioclastic sand 25 to 80 m thick record strong tidal currents the central mediterranean sea has had a microtidal range of ca 35 cm and the local amplification of the tidal wave is attributed to tides enhanced in some of the bays and to the out of phase reversal of the tidal prism in narrow straits linking the tyrrhenian and ionian basins the siliciclastic sediment was generated by local bedrock erosion whereas the bioclastic sediment was derived from the contemporaneous foramol type cool water carbonate factories the cross strata sets represent small to medium sized 10 to 60 cm thick two dimensional dunes with mainly unidirectional foreset dip directions these tidalites differ from the classical tidal rhythmites deposited in mud bearing siliciclastic environments firstly the foreset strata lack mud drapes and instead show segregation of siliciclastic and bioclastic sand into alternating strata secondly the thickness variation of the successive silici bioclastic strata couplets measured over accretion intervals of 2 to 3 m and analysed statistically reveal only the shortest term diurnal and semi diurnal tidal cycles thirdly the record of diurnal and semi diurnal tidal cycles is included within the pattern of neap spring cycles differences between these sediments and classical tidal rhythmites are attributed to the specific palaeogeographic setting of a microtidal sea with the tidal currents locally enhanced in peripheral basins it is suggested that this particular facies of mud free silici bioclastic arenite rhythmites in the stratigraphic record might indicate a specific type of depositional sub tidal environment of straits and embayments and the shortest term tidal cycles

relevance of rock slope deformations in local seismic response and microzonation insights from the accumoli case study central apennines italy abstract based on a national government decree detailed seismic microzonation studies were carried out after the seismic sequence of central italy 2016 2017 in support of post earthquake reconstruction during these activities mass rock creep deformations of slopes were observed in the municipality of accumoli latium region involving two urbanized areas on the left bank of the tronto river the geological and geomorphological surveys as well as the geomechanical characterization of rock masses revealed a deformation process of flexural toppling which involves the sub vertical thick sandstone layers down to 50 m of depth geophysical investigations consisting of downhole tests active surface wave testing and seismic ambient noise measurements were carried out in the areas involved in the deformational processes the results highlighted that the rock mass involved in the flexural toppling exhibits peaks of the horizontal to vertical spectral ratios hvsr in a frequency band ranging from 1 5 up to 2 5 hz in one of the two areas h v calculated on weak motions recorded during the seismic sequence within the deforming rock mass showed a clear peak in the h v frequency range 1 5 2 0 hz the same range pointed out by the ambient vibration analysis due to local morphological lithological and bedding conditions such an evidence cannot be related to a simple 1d resonance due to the seismic impedance contrasts originated from the local stratigraphy nevertheless it seems more reliable that the hvsr peaks can be related to the 3d volume of intensely jointed rock mass in agreement with the field evidence of flexural toppling as these peaks result confined within the deforming mass in addition the lack of a clear polarization of the particle motion in the seismic ambient noise dataset suggests that the observed effect should not be linked to the interaction of seismic surface waves with persistent discontinuities in an anisotropic rock mass according to the national guidelines for seismic microzonation studies these rock masses have not been identified as unstable i e involved in conventional landslide processes but have been identified as seismic amplification prone microzones with associated amplification factors of at least 1 5 in the period range 0 1 0 5 s the identification of such microzones within areas involved in gravity induced slope deformations is a significant prerequisite for planning strategies of post earthquake reconstruction

a paleoclimatic review of southern south america during the late paleozoic a record from icehouse to extreme greenhouse conditions abstract this paper provides a review of the late mississippian to permian paleoclimatic history for southern south america based on lithologic indicators biostratigraphic information and chronostratigraphic data the region is divided into three major types of basins 1 eastern intraplate basins e g parana basin 2 western retroarc basins e g paganzo basin and 3 western arc related basins e g rio blanco basin four major types of paleoclimatic stages are recognized in these basins 1 glacial late visean early bashkirian 2 terminal glacial bashkirian earliest cisuralian 3 postglacial cisuralian early guadalupian and 4 semiarid arid late guadalupian lopingian the glacial stage began in the late visean and continued until the latest serpukhovian or early bashkirian in almost all of the basins in southern south america during the bashkirian earliest cisuralian terminal glacial stage glacial deposits disappeared almost completely in the western retroarc basins e g paganzo basin but glaciation persisted in the eastern basins e g parana and sauce grande basins a gradual climatic amelioration postglacial stage began to occur during the earliest permian when glacial deposits completely disappeared across all of south america during this interval glacial diamictites were replaced by thick coal beds in the parana basin while north south climatic belts began to be delineated in the western basins which were likely controlled by the distribution of mountain belts along the panthalassan margin of south america towards the late permian climatic belts became less evident and semiarid or arid conditions dominated in the southern south america basins eolian dunes playa lake deposits and mixed eolian fluvial sequences occur in the parana basin and in the western retroarc basins volcanism and volcaniclastic sedimentation dominated along the western margin of south america at that time the stratigraphic record obtained in southern south america supports a long duration transition from icehouse to extreme greenhouse conditions

on postglacial sea level summary an exact method is presented for calculating the changes in sea level that occur when ice and water masses are rearranged on the surface of elastic and viscoelastic non rotating earth models the method is used to calculate the instantaneous elastic and delayed vi scoelastic sea level changes following the partial melting of late quaternary ice sheets we find that there can be large errors in the usual assumption that changes in sea level are uniform over the ocean basins if a quantity of ice equivalent to a uniform 100 m rise in sea level melts from the laurentide and fennoscandian ice sheets then in the south pacific the instantaneous rise in sea level can be as large as 120m in the north atlantic the instantaneous rise is always less than 100 m there is a zone in the north atlantic with almost no sea level change and near greenland and norway the sea level falls rather than rises by over 100 m one thousand years after the melting a forebulge migrating towards the ice loads causes water to flow from the south pacific into the north pacific suggesting that raised beaches should occur in the south pacific the gravitational attraction of an ice mass upon a nearby ocean tends to hold sea level high in the vicinity of the ice this extra load near the ice may have a significant influence on postglacial isostatic adjustment

retrieval of historical surface displacements of the baige landslide from time series sar observations for retrospective analysis of the collapse event abstract landslides and resultant barrier lakes are significant threats to human lives and infrastructures three dimensional 3d surface displacements can give vital clues to the exploration of internal structure of landslides but they are difficult to be retrieved from spaceborne synthetic aperture radar sar observations due to the intrinsic limitation of sar imaging geometry meanwhile studies on predicting slope failure based on sar measured displacements are rarely seen here we used sar pixel offset tracking to investigate the baige landslide before the collapse on 10 october 2018 3d surface displacements retrieved by combining satellite sar and optical observations revealed heterogeneous spatial patterns within the landslide complex we observed linear secondary creep and accelerating tertiary creep prior to the failure from multi sensor sar data the possibility of forecasting the failure was demonstrated by applying an inverse velocity method to the time series displacements measured by sentinel 1 during the tertiary creep which is valuable for risk evaluation and disaster early warning

high precision u pb calibration of carboniferous glaciation and climate history paganzo group nw argentina the duration and geographic extent of carboniferous glacial events in southern gondwana remain poorly constrained despite recent evidence for a more dynamic glacial history than previously considered we report 10 high precision 2 0 1 u pb ages for the permian carboniferous paganzo group nw argentina that redefi ne the chronostratigraphy of the late paleozoic paganzo and rio blanco basins and signifi cantly refi ne the timing of glacial events and climate shifts in the western region of southern gondwana radiometric calibration of the paganzo group indicates three pulses of carboniferous glaciation in the mid visean the late serpukhovian to earliest bashkirian and between the latest bashkirian to early moscovian an abrupt shift in depositional style from high sinuosity single storied fl uvial deposits and clay rich paleosols to low sinuosity multi storied feldspathic fluvial deposits inter calated with eolianites and calcic paleosols is constrained to the latest moscovian and earliest kasimovian these constraints indicate a relatively abrupt climate shift from humid subhumid to nonseasonal semiarid regional climate conditions that occurred signifi cantly earlier than previously inferred early permian this period of high latitude aridity was contemporaneous with a shift to dryland depositional environments and a major vegetation regime shift documented throughout the pangean paleotropics in the pennsylvanian

early seed plants from western gondwana paleobiogeographical and ecological implications based on tournaisian lower carboniferous records from argentina the oldest seed occurrences in western gondwana have been recognized in a new stratigraphic section located in western argentina precordillera basin palynological evidence indicates an early mississippian probably tournaisian age for this new succession the two identified early seeds generas pseudosporogonites cf hallei and warsteinia sancheziae n sp were up to now considered as restricted to the devonian of laurussia this finding suggests a dispersal of earliest spermatophytes between laurussia and gondwana during devonian tournaisian times thus accounting for the rheic ocean as a surmountable biogeographic barrier for continental biotas alternatively contrasting biogeographic hypotheses dealing with early spermatophytes rising in paleotropics and then displacing herbaceous communities of non spermatophytes typical from cool high latitudinal regions are explored for explaining the recognized paleobiogeographical pattern the new information supports a weak impact of the devonian carboniferous biotic crisis on earliest seed plant diversity based on preliminary evidences of niches differentiation and ecological dynamics probably affected by wildfires tournaisian gondwanan plant communities from high latitudes are interpreted as being more complex than previously thought and more similar to those reported from laurussia in addition their discovery in a sedimentary environment associated to glacigenic deposits show that this new record might be linked to the coeval glacial age widely recorded elsewhere in gondwana

observation and modelling of the saint etienne de tinee landslide using sar interferometry abstract six different interferograms of the la clapiere landslide were derived from ers 1 sar images during the period aug 20 sept 4 1991 the coherence of the associated images is shown to remain significant over most of the surface of the landslide during the two weeks of the survey the interferograms are remarkably similar and indicate steady state displacements over at least 12 days the displacement field derived from the interferograms is shown to be characterized by a non uniform displacement gradient from top to bottom and reveals a significantly faster motion of the western part of the landslide the amplitude of the motion deduced from interferometry is shown to be in good agreement with ground measurements finally sar interferometry is shown to be able to evidence small scale instabilities which may not be observed with discrete ground measurements

the 17 august 1999 izmit earthquake on 17 august 1999 an earthquake of magnitude 7 4 shook northwestern turkey details on the earthquake9s characteristics and effects across northwestern turkey are provided and are put in the historical context of previous earthquakes in the region the earthquake was the seventh in a series of earthquakes migrating westwards along the north anatolian fault since 1939 information on historical earthquakes modeling and estimates of the slip rate along the fault indicate that the location and severity of the earthquake should not have come as a surprise

stratigraphic imprint of the late palaeozoic ice age in eastern australia a record of alternating glacial and nonglacial climate regime stratigraphic and sedimentological data from new south wales and queensland eastern australia indicate that the late palaeozoic ice age comprised at least eight discrete glacial intervals each 1 8 ma in duration here termed glaciations separated by nonglacial intervals of comparable duration these events spanned an interval from mid carboniferous c 327 ma to the early late permian c 260 ma and illustrate a pattern of increasing climatic austerity and increasingly widespread glacial ice from initial onset until an acme in the late early permian followed by an opposite trend towards the final demise of glaciation in the late permian the alternating glacial nonglacial motif suggests that the late palaeozoic ice age was considerably more dynamic than previously thought these patterns are remarkably consistent with recent interpretations of palaeofloral change eustatic sea level fluctuations and co 2 climate glaciation relationships for this interval of time the detailed record of alternating glacial and nonglacial climate mode disclosed herein may facilitate more closely resolved evaluations of stratigraphic records elsewhere notably in far field ice distal northern hemisphere successions

grenvillian massif type anorthosites in the sierras pampeanas we report the discovery of massif type anorthosites in the andean basement of the western sierras pampeanas of argentina u pb zircon dating by sensitive high resolution ion microprobe of a cogenetic gabbronorite dyke yields ages of 1070 41 ma for igneous emplacement and 431 40 ma for metamorphism these anorthosites are petrologically and geochemically comparable with those of the grenville province of laurentia palaeogeographical reconstructions of rodinia at 1 0 1 1 ga suggest that the sierras pampeanas anorthosites were part of a large anorthosite province in the late mesoproterozoic

low latitude ordovician to triassic brachiopod habitat temperatures bhts determined from δ18o brachiopod calcite a cold hard look at ice house tropical oceans abstract some researchers have suggested that phanerozoic land based ice sheets extended occasionally into the tropical realm if true the tropical ocean at those times must have been distinctly colder than at the last glacial maximum lgm when northern hemisphere ice sheets did not extend below 38 latitude low latitude ocean temperatures derived from oxygen isotopes of brachiopod shells test this hypothesis by comparing the temperature regime for paleozoic and early mesozoic low latitude settings to the tropical temperature regime of the modern interstadial ocean and to mean temperatures estimated for the tropical ocean at lgm a running mean of ph adjusted brachiopod habitat temperatures bhts shows that paleozoic low latitude oceans were on average cool to cold relative to the modern interstadial tropical ocean at times during pennsylvanian serpukhovian tournaisian and ordovician silurian glaciations these tropical seas were indeed significantly colder on average than at the lgm ice sheets within tropical latitudes can be reasonably predicted at those times abundant and diverse paleozoic brachiopod communities reflect these cool tropical oceans consistent with modern brachiopod ecological preference for colder waters amplified paleozoic temperature oscillations suggest recurring global warming events which episodically drove these cold tropical oceans to temperatures significantly higher than the warmest modern tropical ocean

correlation of satellite image time series for the detection and monitoring of slow moving landslides abstract slow moving landslides are widespread in many landscapes with significant impacts on the topographic relief sediment transfer and human settlements their area wide mapping and monitoring in mountainous terrain however is still challenging the growing archives of optical remote sensing images offer great potential for the operational detection and monitoring of surface motion in such areas this study proposes a multiple pairwise image correlation mpic technique to obtain a series of redundant horizontal displacement fields and different multi temporal indicators for a more accurate detection and quantification of surface displacement the technique is developed and tested on a series of monoscopic and stereoscopic pleiades satellite images at a test site in the south french alps empirical tests confirm that mpic significantly increased detection accuracy f measure 0 85 and that the measurement error can be reduced by averaging velocities from all pair combinations covering a given time step i e when stereo pairs are available for at least one date the derived inventory and displacement fields of 169 slow moving landslides show a positive relationship between the landslide size and velocities as well as a seasonal acceleration of the largest landslides in response to an increase in effective precipitation the processing technique can be adapted to better exploit increasingly available time series from a variety of optical satellites for the detection and monitoring of landslide displacement

the magnitude of late paleozoic glacioeustatic fluctuations a synthesis a comprehensive literature review shows that the magnitude of eustatic fluctuations varied throughout the carboniferous and permian and that at least eight distinct phases can be recognized facies juxtapositions in carbonate successions and erosional relief in clastic successions indicate that glacioeustatic fluctuations of 20 25 m and occasionally as much as 60 m took place throughout the early mississippian tournaisian a widely recognized glacial period middle mississippian mid chadian through holkerian shallow marine carbonate and clastic successions indicate that eustatic fluctuations were 10 25 m a decrease that matches well with the paucity of coeval glacial deposits late visean asbian through mid brigantian glacioeustatic fluctuations of 10 50 m record the initial phases of ice accumulation in advance of the widespread mid carboniferous glacial event the latest mississippian earliest pennsylvanian mid brigantian through langsettian was a time of widespread glaciation and strata of this age commonly exhibit evidence of glacioeustatic fluctuations of as much as 40 100 m although middle pennsylvanian duckmantian through asturian glacial deposits are present in eastern australia paleovalley depths suggest that coeval glacioeustatic fluctuations were less than 40 m glacioeustatic fluctuations of as much as 100 120 m have been widely reported from late pennsylvanian earliest permian stephanian through mid sakmarian successions in north america an increase that corresponds to the growth of large ice sheets across much of gondwana and the accumulation of ice in the northern hemisphere incision and facies juxtaposition in early middle permian mid sakmarian through kungurian successions in eastern australia indicate that glacioeustatic fluctuations of 30 70 m occurred during the waning stages of major glaciation erosional relief in paleoequatorial carbonates and the presence of coeval glacial deposits in australia suggests that eustatic fluctuations of 10 60 m occurred during the final stages of glaciation in the middle to late permian roadian through capitanian but the modest size of most of these fluctuations makes it difficult to isolate the glacioeustatic signature this review demonstrates that far field cyclic successions record changing glacial conditions in gondwana that the magnitude of glacioeustatic fluctuations was directly related to the volume of glacial ice that carboniferous permian glacioeustasy was more variable than previously recognized and that generalizations from short temporal intervals are probably not representative of the late paleozoic ice age as a whole although any attempt to quantify the magnitude of ancient eustatic changes is based on caveats and assumptions this review incorporates the results of over 100 published papers on the topic in an attempt to minimize the errors inherent in any one study

the failure of carsington dam the upstream slope of carsington dam failed just before its completion in 1984 the slip started on the right abutment and spread across the valley to a length of nearly 500m extensive investigations were conducted and further information was obtained when the dam was reconstructed the initial slip sheared through the core which contained shear surfaces due to rutting and along a layer of yellow clay which contained solifluction shears both materials were brittle with low residual strengths the factor of safety based on measured peak strengths was about 1 4 with reductions to allow for shears it was 1 2 it had been reduced to 1 0 by progressive failure finite element fe analyses in which strain softening was reproduced confirmed this it was concluded that the slide spread by lateral load transfer through sections of the dam with a safety factor greater than 1 in the vailey centre the slide passed through the base of the mudstone fill a combination of fe and limit equilibrium analysis ind

evaluating sub pixel offset techniques as an alternative to d insar for monitoring episodic landslide movements in vegetated terrain article spaceborne synthetic aperture radar sar sensors obtain regular and frequent radar images from which ground motion can be precisely detected using a variety of different techniques the ability to measure slope displacements remotely over large regions can have many uses although the limitations of the most common place technique differential insar d insar must be considered prior to interpreting the final results one such limitation is the assumption that different rates of movement over a given distance cannot exceed a thresh old value dependent upon the pixel spacing of the sar images and the radar wavelength characteristic features of landslides i e the sharp boundary between stable active ground and the range of temporally variable veloc ities can exhibit high spatial displacement gradients breaking a fundamental assumption for reliable d insar analysis areas of low coherence are also known to hinder the exploitation of insar data this study assesses the capability of terrasar x spotlight terrasar x stripmap and envisat stripmap images for monitoring the slow moving shuping landslide in the densely vegetated three gorges region china in this case study the epi sodic nature of movement is shown to exceed the measurable limit for regular d insar analysis even for the highest resolution 11 day tsx spotlight interferograms a sub pixel offset time series technique applied to cor ner reflectors spot cr using only the sar amplitude information is applied as a robust method of resolving time varying displacements with verifiable offset measurements presented from tsx spotlight and tsx