basal ice facies and supraglacial melt out till of the laurentide ice sheet tuktoyaktuk coastlands western arctic canada glacially deformed massive ice and icy sediments mi is in the eskimo lakes fingerlands and summer island area of the tuktoyaktuk coastlands western arctic canada show in the same stratigraphic sequences features characteristic of both basal glacier ice and intrasedimental ice basal ice features comprise 1 ice facies and facies groupings similar to those from the basal ice layers of contemporary glaciers and ice sheets in alaska greenland and iceland 2 ice crystal fabrics similar to those from basal ice in antarctica and ice cored moraines on axel heiberg island canada and 3 a thaw or erosional unconformity along the top of the mi is buried by glacigenic or aeolian sediments intrasedimental ice consists of pore ice and segregated ice formed within pleistocene sands deposited before glacial overriding the co existence of basal and intrasedimental ice within the mi is records their occurrence within the basal ice layer of the laurentide ice sheet stagnation of the ice sheet and melt out of till from the ice surface allowed burial and preservation of the basal ice layer on a regional scale the widespread occurrence of supraglacial melt out till with clast fabrics similar to those in the underlying ice suggests that such till can be well preserved during partial thaw of a continental ice sheet in lowlands underlain by continuous permafrost

paleomagnetic study of plio pleistocene sediments in the concentrated deformation zone along the eastern margin of the japan sea abstract paleomagnetic results are presented for a concentrated deformation zone cdz in a convergent plate boundary region along the eastern eurasian margin we sampled late pliocene early pleistocene tuffs and clastic sediments of the sasaoka formation 750 m thick in northeastern honshu japan to test whether the late pliocene quaternary crustal deformation within the cdz along the eastern margin of the japan sea was accompanied by rotation about a vertical axis rock magnetic experiments suggest that the principal magnetic carrier is magnetite in the fine tuffs and magnetic iron sulfide in the fine sandstones pre folding characteristic remanent magnetization was confirmed using a positive bootstrap fold test we obtained 21 acceptable site mean characteristic directions that include our preliminary published results and which cover an interval from ca 2 7 to 1 7 ma on the basis of magnetostratigraphic correlations an updated age depth model is given and this allowed us to make numerical age estimates for key interbedded tuff beds tephras a positive fold test also suggests that the gojome syncline began to develop after 1 7 ma which means the folding began long after the initiation of late pliocene crustal shortening in northeastern honshu after 100 unfolding the overall mean direction d 359 7 i 54 9 95 6 7 is indistinguishable from the geocentric axial dipole field direction indicating that the gojome syncline the most prominent structural element in the study area developed without vertical axis rotation a comparison of our results with plio pleistocene directions reported from other areas reveals no paleomagnetically detectable rotation in or adjacent to the cdz except for local rotation near strike slip faults in central honshu

pingos in antarctica abstract pingos or ice cored mounds are described for the first time from antarctica and for the first time on ice cored moraine seven pingos up to 4 m high and 12 m in diameter occur on former dering of lakes on the moraine exposes water saturated sediments to freezing and consequent lake sediments on flanders moraine vestfold hills antarctica 68 40 s 78 00 e lateral wandering formation of closed system pingos the pingos are probably only a few hundred years old the apparent absence of pingo scars in the southern hemisphere may be due to lack of suitable substrates rather than to unsuitable climatic conditions

reinterpretation of pingos in antarctica abstract in 1983 pingos were reported in the vestfold hills antarctica the features form dome shaped hills up to 4 m high and 12 m in diameter and occur on an ice cored moraine their form structure and sedimentary processes observed on the surface of the moraine together with a consideration of the environmental requirements for pingo growth preclude their origin as pingos they appear to be residual landforms that have formed on the surface of the moraine as the ice core has been destroyed by ablation and thermal erosion the previous interpretation of the features has relied on the shape of the hills and their occurrence in a similar geologic setting to pingos in the northern hemisphere the interpretation appears to have misinterpreted tension cracks and coherent slumping of sediment as dilation cracks and as evidence for the extrusion of a central sediment plug pingos on supraglacial debris have not been described from any other locations and it seems that their formation is inconsistent with the ablation of the ice core of moraines

link between major flank slip and 2002 2003 eruption at mt etna italy 1 the 2002 2003 etna eruption is studied through earthquake distributions and surface fracturing in september 2002 earthquake induced surface rupture sinistral offset 0 48 m occurred along the e w striking pernicana fault pf on the ne flank in late october a flank eruption accompanied further 0 77 m surface rupturing reaching a total sinistral offset of 1 25 m the deformation then propagated for 18 km eastwards to the coastline sinistral offset 0 03 m and southwards along the nw se striking timpe dextral offset 0 04 m and later trecastagni faults dextral offset 0 035 m seismicity 4 km bsl on the e flank accompanied surface fracturing fault plane solutions indicate an overall ese wnw extension direction consistent with ese slip of the e flank also revealed by ground fractures a three stage model of flank slip is proposed inception september earthquake climax accelerated slip and eruption and propagation e and s migration of the deformation

observations on a debris covered polar glacier whisky glacier james ross island antarctic peninsula antarctica on etudie la structure d un glacier polaire dans lequel des couches de debris atteignent la surface pour generer une aire tres vaste de glace couverte de debris

a physically based 3 d model of ice cliff evolution over debris covered glaciers we use high resolution digital elevation models dems from unmanned aerial vehicle uav surveys to document the evolution of four ice cliffs on the debris covered tongue of lirung glacier nepal over one ablation season observations show that out of four cliffs three different patterns of evolution emerge i reclining cliffs that flatten during the ablation season ii stable cliffs that maintain a self similar geometry and iii growing cliffs expanding laterally we use the insights from this unique data set to develop a 3 d model of cliff backwasting and evolution that is validated against observations and an independent data set of volume losses the model includes ablation at the cliff surface driven by energy exchange with the atmosphere reburial of cliff cells by surrounding debris and the effect of adjacent ponds the cliff geometry is updated monthly to account for the modifications induced by each of those processes model results indicate that a major factor affecting the survival of steep cliffs is the coupling with ponded water at its base which prevents progressive flattening and possible disappearance of a cliff the radial growth observed at one cliff is explained by higher receipts of longwave and shortwave radiation calculated taking into account atmospheric fluxes shading and the emission of longwave radiation from debris surfaces the model is a clear step forward compared to existing static approaches that calculate atmospheric melt over an invariant cliff geometry and can be used for long term simulations of cliff evolution and to test existing hypotheses about cliffs survival

depositional models for moraine formation in east antarctic coastal oases this paper examines the origin of moraine ridges in east antarctic coastal oases and derives depositional models appropriate for the reconstruction of quaternary history on the basis of morphology structure and sedimentology four principal types of ridge may be identified 1 type a moraines form whenthe basal debris zone crops out near an ice margin 2 type b moraines form when large recumbent folds develop in the basal debris zone 3 type c moraines are ice contact screes and fans which form when debris accumulates at streep or cliffed ice margins and 4 type d moraines are thrust block moraines that form when unconsolidated sediment is entrained by freezing shearing and thrusting of sediment blocks at the base of the glacier simple calcumations of the rate of debris accumulation at ice margins suggest that type a b and c moraines take thousands of years to form and record stable ice margins type d moraines are structural features that may form relatively quickly when ice margins override unconsolidated sediment constructing models to explain the origin of the moraines is an important part of reconstructing the quaternary history of antarctic coastal oases because the models provide a basis for reconstructing the position and behaviour of the ice sheet during advance and retreat

paleodepth determination from antarctic benthic diatom assemblages abstract analysis of modern surface sediments from fjords in the vestfold hills antarctica indicates that 58 of the variation in benthic diatom assemblages can be attributed to changes in environmental parameters with water depth attenuation of light through the water column is suggested to account for 45 of the variation and the decrease in substrate grain size with depth possibly accounts for a further 13 cluster analysis and principal component analysis were used to objectively circumscribe five floral zones between the surface and 35 m depth the depth distribution of the benthic diatoms was then used to interpret the paleodepth of relict fjord holocene sediments exposed around deep lake in the death valley vestfold hills paleodepths measured from the sea ice bench around deep lake combined with data from grain size analysis indicate that the relict fjord sediments have no analogue amongst the modern fjord sediments sampled in the vestfold hills without a comparable modern habitat on which to model the diatom depth zones however this study was unable to accurately determine the paleowater depth at deep lake using diatoms paleodepth determination will be possible using grain size analysis and diatom data when the substrate and light requirements of benthic diatoms are understood

cosmogenic evidence for limited local lgm glacial expansion denton hills antarctica abstract the geomorphology of the denton hills provides insight into the timing and magnitude of glacial retreats in a region of antarctica isolated from the influence of the east antarctic ice sheet we present 26 beryllium 10 surface exposure ages from a variety of glacial and lacustrine features in the garwood and miers valleys to document the glacial history of the area from 10 to 286 ka our data show that the cold based miers joyce and garwood glaciers retreated little since their maximum positions at 37 2 6 9 1 n 4 35 1 1 5 1 n 3 and 35 6 10 1 1 n 6 ka respectively the similar timing of advance of all three glaciers and the lack of a significant glacial expansion during the global lgm suggests a local lgm for the denton hills between ca 26 and 51 ka with a mean age of 36 0 7 5 1 n 13 ka a second cohort of exposure ages provides constraints to the behaviour of glacial lake trowbridge that formerly occupied miers valley in the late pleistocene these data show active modification of the landscape from 20 ka until the withdrawal of ice from the valley mouths and deposition of ross sea drift at 10 14 ka

seismological features of the pernicana provenzana fault system mt etna italy and implications for the dynamics of northeastern flank of the volcano abstract the pernicana provenzana fault system is one of the most active tectonic systems of mt etna and it plays an important role in the dynamic of the eastern flank of the volcano earthquakes occurring close to this structural trend have reached magnitudes up to 4 2 sometimes with coseismic surface faulting and have caused severe damages to tourist resorts and villages in the vicinity of this structure in the last decade a large number of shocks sometimes in the form of swarms linked to pernicana provenzana fault system movements have been detected by the permanent local seismic network operating in eastern sicily in this paper we report on the detailed study of the seismic activity occurring during the 2000 2009 time span in the pernicana provenzana fault system area firstly we located 407 earthquakes using a standard location code and a 1d crustal velocity model we then applied two different approaches to calculate precise hypocenter locations of the events in particular a non linear code was adopted to obtain an estimate of the a posteriori probability density function in 3d space for the hypocenter location moreover a relative location of correlated event pairs was performed using the double difference method these two different location approaches allowed defining with good accuracy the most active and hazarding sectors of the structure the results of these precise locations showed a tighter clustering in the epicenters and in focal depths in comparison with standard locations earthquakes are located along the pernicana provenzana fault system and are mainly clustered in two zones separated by an area with very low rate of earthquakes occurrence but characterized by the highest energy release depths of the foci are very shallow ranging between the surface and about 3 km b s l kinematics of the pernicana provenzana fault system revealed by the fault plane solutions computed for the most energetic earthquakes highlights a predominant dip slip and left strike movements along e w oriented fault planes in agreement with field observations

double saloon door tectonics in the japan sea fossa magna and the japanese island arc abstract a number of criteria considered diagnostic of double saloon door rifting and seafloor spreading are matched by data from the japanese arc these include i a pair of terranes sw and ne honshu which rotated in opposite directions from 22 21 ma to 14 11 ma ii rotated terranes which comprise a retro arc fold thrust belt attached to an accretionary wedge intruded by a magmatic arc iii contemporaneous backarc extension from 24 to 21 ma which is brought to a halt by progressive collision of the izu bonin and japan arcs from 15 to 5 ma iv isolation of blocks of thicker continental crust by areas of thin continental or oceanic crust during backarc rifting v such isolation may be due to simultaneous rifting or to progressively seaward rifts associated with ridge jumps towards the subduction zone vi opposite rotations are accommodated by subduction rollback demonstrated by seaward migration of the volcanic front from 30 26 ma to 16 15 ma vii concurrent development of a major arc orthogonal rift the fossa magna from 23 18 ma to 14 ma which was thereafter inverted from 15 ma to the recent viii a northeast propagating rift in the northern japan basin demonstrated by the relationship of linear magnetic anomalies to the mapped continent ocean boundary driving mechanisms for double saloon door tectonics are discussed in relation to various reconstructions of the northwest pacific opposite rotational torques leading to opposite terrane rotations may be caused by rollback of a curved trench hingeline or by the divergent slab sinking forces of the pacific and philippine sea plates

changes in heat released by hydrothermal circulation monitored during an eruptive cycle at mt etna italy the shallow vertical temperature profile has been measured in the proximity of an eruptive fissure far about 4 km north northeast from mt etna central craters the monitoring site was a steam heated soil lying between a group of flank fractures on the upper northeast flank of mt etna italy i e on the northeast rift we chose this area because it was close to an eruptive fissure that opened in 2002 and extended from about 2500 to about 1500 m a s l with our aim being to determine a connection between this fracture system and the ongoing volcanic activity heat flux anomalies from the ground from september 2009 to september 2012 were evaluated changes in the hydrothermal release which can be related to variations in volcanic activity are discussed and compared to the published geophysical data the heat flux ranges varied during the pre eruptive from about 7 to 38 w m 2 syn eruptive from about 3 to 49 w m 2 and post eruptive phases with the heat released being lowest at the latter phase from about 1 to 20 w m 2 moreover the heat flux time variation was strongly correlated with the eruption rate from the new southeast crater between january 2011 and april 2012 the migration of magma through active conduits acts as a changing heating source for steam heated soils located above the active fractures our findings suggest that tracking the heat flux above active fractures constitutes a useful investigation field for low cost thermal monitoring of volcanic activity time variations in their emissions could highlight the relationship between a hydrothermal circuit and the local network of fractures possibly indicating variation in the structural weakness of a volcanic edifice continuous monitoring of heat flux combined with a realistic model would contribute to multidisciplinary investigations aimed at evaluating changes in volcano dynamics

supraglacial eskers in antarctica abstract this paper describes eskers that form at the edge of the ice sheet in the vestfold hills antarctica eskers are linear ridges that are deposited by streams constrained by glacier ice their formation requires a sediment source and the presence of meltwater capable of thermal erosion and penetration of glacier ice these requirements mean that eskers are generally associated with temperate glaciers and are not usually associated with cold polar glaciers the eskers described in this paper form small ridges of gravel adjacent to ice cored moraines the form orientation sedimentary properties together with consideration of the field relationships suggests they were formed by supraglacial streams that drain moraine dammed lakes and recycle sediment deposited on ice cored moraines the small size of the eskers combined with the active nature of ice marginal processes in the area means the eskers have a low preservation potential and do not occur beyond the ice margin in the vestfold hills

what controls dead ice melting under different climate conditions a discussion abstract in the geological record hummocky dead ice moraines represent the final product of the melt out of dead ice processes and rates of dead ice melting in ice cored moraines and at debris covered glaciers are commonly believed to be governed by climate and debris cover properties here backwasting rates from 14 dead ice areas are assessed in relation to mean annual air temperature mean summer air temperature mean annual precipitation mean summer precipitation and annual sum of positive degree days the highest correlation was found between backwasting rate and mean annual air temperature however the correlation between melt rates and climate parameters is low stressing that processes and topography play a major role in governing the rates of backwasting the rates of backwasting from modern glacial environments should serve as input to de icing models for ancient dead ice areas in order to assess the mode and duration of deposition a challenge for future explorations of dead ice environments is to obtain long term records of field based monitoring of melt progression furthermore many modern satellite borne sensors have high potentials for recordings of multi temporal digital elevation models dems for detection and quantification of changes in dead ice environments in recent years high accuracy dems from airborne laser scanning altimetry lidar are emerging as an additional data source however time series of high resolution aerial photographs remain essential for both visual inspection and high resolution stereographic dem production

piggyback tectonics long term growth of kilauea on the south flank of mauna loa abstract compositional and age data from offshore pillow lavas and volcaniclastic sediments along with on land geologic seismic and deformation data provide broad perspectives on the early growth of kilauea volcano and the long term geometric evolution of its rift zones sulfur rich glass rinds on pillow lavas and volcaniclastic sediments derived from them document early underwater growth of a large compositionally diverse alkalic edifice the alkalic rocks yield 40ar 39ar ages as old as about 275 ka transitional composition lavas which mark beginning of the shield stage while most or all the edifice remained below sea level probably first erupted after about 150 ka and tholeiitic lavas of present day type are probably younger than 100 ka breccia clasts from papau seamount and along the lower southwest corner of the hilina bench are derived from subaerial mauna loa requiring that mauna loa s flank underlies western parts of kilauea at shallow depth the volume of the kilauea edifice is therefore smaller 10 000 km3 than previous estimates 15 40 000 km3 lava thickness accumulation rates appear to have remained nearly constant during edifice growth as effusion rates increased from 25 106 m3 yr at end of the alkalic stage to the present day tholeiite rate of 100 106 m3 yr seismic and gravity data show that the deep plumbing system for kilauea s magma supply extends nearly vertically through the oceanic crust at least to mantle depths of 30 35 km directly below its present day caldera proximity of kilauea s caldera to the surface boundary with mauna loa and the presence of mauna loa rocks at shallow depth beneath the south flank are difficult to reconcile with a submarine origin for early kilauea alkalic lavas unless geometric relations between the two volcanoes have changed substantially during growth of the kilauea shield seismic and ground deformation data suggest seaward spreading of the entire south flank of hawaii island independently of the boundary between kilauea and mauna loa along a landward dipping detachment fault system near the basal contact of the composite volcanic edifices with underlying oceanic crust current steady state horizontal displacements increase seaward at rates of 1 5 cm yr on the lower flank of mauna loa and reaching 5 8 cm yr at the kilauea coastline infrequent 100 yr large earthquakes generate similar geometries but 102 larger displacements per event present day kilauea is the more dynamic edifice but prior to inception of kilauea and during its early growth mauna loa is inferred to have undergone intense volcano spreading involving the kaoiki honuapo fault system considered a geometric analog of the hilina system on kilauea cumulative deformation of mauna loa s south flank during growth of kilauea since 200 300 ka is estimated to have involved 10 km of seaward spreading displacing the rift zones of k lauea while its deep plumbing system and summit magma reservoir remained nearly fixed in space kilauea s rift zones rather than migrating southward with time solely due to dike emplacement preferentially on the mobile seaward side alternatively are interpreted to have been transported passively southward piggyback style during shield stage growth of kilauea as a blister on the still mobile south flank of mauna loa such an evolution of kilauea accounts for the arcuate geometry of the present day rift zones proximity of the summit magma supply to the exposed flank of mauna loa initial submarine growth of the ancestral edifice and present day location of mauna loa rocks at shallow depth beneath the south flank of kilauea

entrainment of glaciomarine sediments and formation of thrust block moraines at the margin of sorsdale glacier east antarctica the morphology sedimentology and structure of moraines at the margin of an outlet glacier in east antarctica are described and contemporary depositional processes in a marine inlet adjacent to the ice margin are examined results indicate that the principal moraines are thrust block moraines produced by basal freezing and deformation of glaciomarine sediment as the outlet glacier expands into a marine inlet preservation of detailed glaciomarine sedimentary structures and beds of marine shells suggests that the sediment was frozen during entrainment transportation and deposition the presence of low angle faults in the moraines show that the moraines consist of an en echelon arrangement of thrust plates the sedimentology structure thickness of the thrust plates and inferred entrainment processes are consistent with weertman s ice debris accretion hypothesis for debris entrainment at the edge of cold ice sheets a model of thrust block moraine development produced by this study provides a framework for the interpretation of radiocarbon dates from marine macrofossils in the moraines the model may also be useful in the interpretation of similar moraines in coastal east antarctic oases and other polar marginal marine environments 1997 by john wiley sons ltd

transient post glacial processes on mars geomorphologic evidence for a paraglacial period abstract on earth a transitional phase between glacial and interglacial periods is referred to as the paraglacial period this period immediately postdates glacial retreat and is characterized by ice removal glacial unloading and the exposure of steep slopes and large sediment stores these responses led to the development of a suite of morphologic units e g talus cones gullies sackungen and polygons which when observed together are indicative of the paraglacial period a similar period of transitional climate and deglaciation is identified on mars in the late amazonian characterized by the association of features in a glaciated 10 6 km diameter mid latitude crater this crater contains concentric crater fill ccf formed by debris covered glaciers as well as a suite of stratigraphically younger geomorphic units e g spatulate depressions washboard terrain gullies and polygonal terrain that are all indicative of the local environmental response to deglaciation these features are interpreted to represent a geologically recent martian paraglacial period within this crater the morphology and relative stratigraphic relationships among these paraglacial features are described in order to assess the processes operating during deglaciation and to document the recent history of glaciation on mars spatulate depressions formed by the differential sublimation of pure glacial ice near the base of the crater wall subsequently due to the loss of basal support and steepened slopes remnant ice on the crater wall began to flow downhill and formed transverse crevasses that created washboard terrain continuous thermal cycling of sediment mantled ice on crater walls created fractures that formed polygonal terrain during this time and after gullies formed by the transport of sediment downslope from crater rim alcoves analyses of modeled obliquity variations suggest that the paraglacial period could have operated within the last 5 myr and may still be ongoing suggesting that the current martian paraglacial period is much longer in duration than typical paraglacial periods on earth understanding the nature and sequence of paraglacial activity can help to identify variations in climate in recent mars history

paraglacial redistribution of glacial sediments in the vestfold hills east antarctica abstract the vestfold hills landscape is dominated by bare rock slopes and unconsolidated deposits form a minor component of the surficial geology the principal objectives of the study were to explain the distribution of unconsolidated deposits determine the nature and timing of sedimentary processes during and after deglaciation and the impact of these processes on landscape development observations of late quaternary glaciation and deglaciation of the area and contemporary depositional processes are reported and a conceptual model of geomorphological change since deglaciation is presented the model attempts to reconcile the types and rates of contemporary depositional processes with the distribution of deposits and landforms and to explain why unconsolidated deposits cover less than 20 of the hills despite the effects of recent glaciation the lack of unconsolidated deposit in the landscape can be attributed to the combined effects of low debris volumes in the ice and the redistribution of debris during and after deglaciation redistribution of debris can be explained by paraglacial processes which are non glacial sedimentary processes that are directly conditioned by glaciation paraglacial sedimentation is a response to rapid adjustment of the debris system after the dominance of glacial conditions and is characterized by disequilibrium between sediment supply and transportation of sediment by nonglacial processes evidence from the vestfold hills suggests paraglacial sedimentary processes are dominated by mass movement of glacial debris from slopes and the formation of stable valley fills and that the main sediment transfers occur within a few thousand years of deglaciation

magnetobiochronology of lower miocene ramblian continental sediments from the tudela formation western ebro basin spain abstract the calibration of european lower miocene continental stages is poorly constrained due to the lack of robust magnetostratigraphic data from continental sediments of this age in this paper we present the first magnetostratigraphic results from the mammal fossil bearing continental sediments of the lower middle miocene tudela formation western ebro basin spain the study is based on 331 paleomagnetic sites distributed along a 790 m thick composite section the resulting magnetostratigraphy provides an independent correlation to the geomagnetic polarity time scale and allows accurate dating of previously known and new ramblian upper lower miocene fossil localities of the tudela formation the new age constraints derived for the tudela formation fossil localities provide together with a revaluation of other iberian faunas the first magnetochronology for the ramblian continental stage the lower boundary of the ramblian is placed at the lower part of chron c6r ca 20 4 ma and the boundary between the lower and upper ramblian is located at the middle of chron c6n ca 19 6 ma the upper boundary of the ramblian and hence the base of the aragonian is placed at the upper middle part of chron c5cr 16 8 17 ma our results also provide the first magnetostratigraphically dated mn3 faunas in spain which together with a revaluation of other iberian and european faunas provide a revised calibration of european mammal zone mn3 the lower boundary of zone mn3 is placed at the boundary between chrons c6r and c6n ca 20 1 ma and its upper boundary is located at the upper middle part of chron c5cr 16 8 17 ma

eocene to miocene magnetostratigraphy biostratigraphy and chemostratigraphy at odp site 1090 sub antarctic south atlantic at ocean drilling program odp site 1090 lat 42854 89s long 8854 09e located in a water depth of 3702 m on the agulhas ridge in the sub antarctic south atlantic 300 m of middle eocene to middle miocene sediments were recovered with the advanced piston corer apc and the extended core barrel xcb u channel samples from the 70 230 meters composite depth mcd interval provide a magnetic polarity stratigraphy that is extended to 380 mcd by shipboard whole core and discrete sample data the magnetostratigraphy can be interpreted by the fit of the polarity zone pattern to the geomagnetic polarity time scale gpts augmented by isotope data and bioevents with documented correlation to the gpts three normal polarity subchrons c5dr 1n c7ar 1n and c13r 1n not included in the standard gpts are recorded at site 1090 the base of the sampled section is correlated to c19n middle eocene although the interpretation is unclear beyond c17r the top of the sampled section is correlated to c5cn late early miocene although in the uppermost 10 m

melt out till in the edmonton area alberta canada till at two localities in the edmonton area alberta was formed mainly by passive melt out from glacier ice and not by lodgment by active ice or as a result of supraglacially derived flows this interpretation is based on the implications of in situ stratified glacial sediment below and within till and of large unlithified clasts of sediment derived from subtill deposits the interpretation is also supported by more general regional stratigraphic and structural observations such associated properties as subtill deformation a sharply planar till preglacial sediment contact sole marks and fabric support formation by melt out or illustrate local exceptions to this process regionally consistent preferred orientation of clasts is interpreted to represent preferred englacial orientation collective analysis of the principal eigenvectors of individual englacial fabrics and flow or resedimented till fabrics from a modem glacial environment and similar analysis for till at villeneuve near edmonton show the edmonton till to occupy the intermediate position in terms of orientation strength predicted by the melt out hypothesis in places preferred orientation is considered to have been disturbed by flow and diapirism induced by the process of thaw consolidation thus preferred clast orientation in till may show considerable deviation from a regional trend stratigraphy and sedimentology are used to classify the till and to relate individual exposures to regional environments of deposition

late holocene changes in character and behaviour of land terminating glaciers on james ross island antarctica virtually no information is available on the response of land terminating antarctic peninsula glaciers to climate change on a centennial timescale this paper analyses the topography geomorphology and sedimentology of prominent moraines on james ross island antarctica to determine geometric changes and to interpret glacier behaviour the moraines are very likely due to a late holocene phase of advance and featured 1 shearing and thrusting within the snout 2 shearing and deformation of basal sediment 3 more supraglacial debris than at present and 4 short distances of sediment transport retreat of 100m and thinning of 15 20m has produced a loss of 0 1km3 of ice the pattern of surface lowering is asymmetric these geometrical changes are suggested most simply to be due to a net negative mass balance caused by a drier climate comparisons of the moraines with the current glaciological surface structure of the glaciers permits speculation of a transition from a polythermal to a cold based thermal regime small land terminating glaciers in the northern antarctic peninsula region could be cooling despite a warming climate

stability of supraglacial debris rock debris on the surface of ablating glaciers is not static and is often transported across the ice surface as relief evolves during melt this supraglacial debris transport has a strong influence on the spatial distribution of melt and is implicated in the formation of hummocky glacial topography in deglaciated terrain furthermore as ice dammed lakes and ice cored slopes become increasingly common in deglaciating watersheds there is rising concern about hazards to humans and infrastructure posed by mass wasting of ice cored debris the existing quantitative framework for describing these debris transport processes is limited making it difficult to account for transport in mass balance hazard assessment and landscape development models this paper develops a theoretical framework for assessing slope stability and gravitational mass transport in a debris covered ice setting excess water pressure at the interface between ablating ice and lowering debris is computed by combining darcy s law with a meltwater balance a limit equilibrium slope stability analysis is then applied to hypothetical debris layers with end member moisture conditions derived from a downslope meltwater balance that includes production and seepage the resulting model system constrains maximum stable slope angles and lengths that vary with debris texture thickness and the rate of meltwater production model predictions are compared with field observations and with digital elevation model dem derived terrain metrics from two modern debris covered glaciers on mount rainier usa copyright 2017 john wiley sons ltd

source model for the 2001 flank eruption of mt etna volcano 1 using interferometric synthetic aperture radar insar we constrain the deformation sources for the july august 2001 flank eruption of mt etna volcano italy insar data from ascending and descending passes of the ers2 satellite reveal a pattern of deformation that cannot be explained by a dike intrusion alone in addition to a vertical dike beneath the south rift zone the spatially large 10 km scale 15 20 cm in range negative range displacement lobes across the western descending data and eastern ascending data flanks require a nearly symmetric set of shallowly dipping normal faults to each side of the central dike complexity in the observed insar surface displacements constrains an additional dike intrusion beneath its ne flank long term deformation of etna s eastern and southern flanks is well established through field and insar observations therefore the relative symmetry of motion beneath both the western and eastern flanks during the 2001 eruption is surprising our model of symmetric flank motion suggests that on the short time scales of a large dike intrusion volcanoes can deform differently from their long term deformation

quantifying ice cliff evolution with multi temporal point clouds on the debris covered khumbu glacier nepal measurements of glacier ice cliff evolution are sparse but where they do exist they indicate that such areas of exposed ice contribute a disproportionate amount of melt to the glacier ablation budget we used structure from motion sfm photogrammetry with multi view stereo mvs to derive 3d point clouds for nine ice cliffs on khumbu glacier nepal in november 2015 may 2016 and october 2016 by differencing these clouds we could quantify the magnitude seasonality and spatial variability of ice cliff retreat mean retreat rates of 0 30 to 1 49 cm d 1 were observed during the winter interval november 2015 to may 2016 and 0 74 to 5 18 cm d 1 were observed during the summer may 2016 to october 2016 four ice cliffs which all featured supraglacial ponds persisted over the full study period in contrast ice cliffs without a pond or with a steep back slope degraded over the same period the rate of thermo erosional undercutting was over double that of subaerial retreat overall 3d topographic differencing allowed an improved process based understanding of cliff evolution and cliff pond coupling which will become increasingly important for monitoring and modelling the evolution of thinning debris covered glaciers

importance of gravitational spreading in the tectonic and volcanic evolution of mount etna the interaction between gravity and thermal effects largely determines the structural and magmatic evolution of volcanic constructs at scales spanning several orders of magnitude from small cones to the oceanic crust1 3 although gravitational spreading is a direct consequence of this interaction and a fundamental process in volcano growth it is rarely recognized as such here we describe a striking example of this process at etna volcano in italy the volcano and its clay rich substratum are slowly spreading towards the east and south driven by gravity spreading produces extensional structures in the summit region and contpressional structures at the base of the volcano eastward movement of the volcanic edifice over a stationary magma supply may be the cause of an apparent westward migration of volcanic activity as gravitational spreading seems to control the location and magnitude of shallow seismicity and flank eruptions an appreciation of its effects could become an essential element of future volcanic hazard evaluation our model proposed here for etna may also be relevant to a reinterpretation of the geological history of a number of other volcanoes

structural assessment of mount etna volcano from permanent scatterers analysis a study of the deformation pattern of mount etna volcano based on the results from the permanent scatterers ps technique is reported ground motion data provided by the interferometric synthetic aperture radar insar ps technique from 1995 to 2000 are compared and validated by gps data an analysis of the ascending and descending line of sight los components of ground velocities has yielded detailed ground deformation maps and cross sections this analysis allows detection and constraint of discontinuities in the surface velocity field los velocities have then been combined to calculate the vertical and horizontal e w ground velocities a wide inflation of the edifice has been detected on the western and northern flanks over an area of about 350 km2 a seaward motion of the eastern and southern flanks has also been measured ps data allows the geometry and kinematics of the several blocks composing the unstable flanks to be defined even in the highly urbanized areas and their displacement rates have been measured with millimeter precision this analysis reveals the extension of some features beyond their field evidences and defines new important features the results of this work depict a new comprehensive kinematic model of the volcano highlighting the gravitational reorganization of the unbuttressed volcanic pile on its slippery clay basement on the southern flank but an additional drag force due to a strong subsidence of the continental margin facing the etna volcano is necessary to explain the ps velocity field observed on the eastern flank

uranium series accessory crystal dating of magmatic processes complex and protracted crystallization histories over geologic timescales are recorded in accessory minerals e g zircon allanite although magmatic crystallization was traditionally assumed to occur essentially instantaneously for the purposes of interpreting mineral geochronometers with low absolute time resolution for ancient samples it emerged relatively recently that magmatic crystallization can occur over extended durations this discovery arose from applying high spatial resolution accessory mineral dating techniques for uranium series isotopes to young volcanic and cognate plutonic rocks the emerging pattern from these studies is that individual crystals and crystal populations record crystallization episodes lasting from 1 000 to many hundreds of thousands of years accessory mineral dating of volcanic rocks and cognate plutonic xenoliths opens new research avenues for crystal age fingerprinting that correlates pyroclastic deposits lavas and plutonic rocks by using characteristic age dis

magnetostratigraphy of an early middle miocene loess soil sequence in the western loess plateau of china 1 stratigraphy and magnetic susceptibility of the quaternary eolian deposits at different sites in china can be closely correlated confirming their spatial coherence and temporal continuity the extent to which these conclusions are true for the miocene loess soil sequences remains to be addressed here a 231 9 m eolian section qa iii is geomagnetically dated yielding an age span of 21 4 11 4 ma with the portion older than 19 6 ma being partially water reworked the magnetozones litholigic structure and magnetic susceptibility of the sequence are highly correlative with the qa i and qa ii sections 30 km west of qa iii these sequences demonstrate that the miocene loess deposits are also spatially correlative in stratigraphy present a near continuous sequence of paleoenvironment changes and that magnetic susceptibility is a useful tool for stratigraphic correlation the basal age of qa iii confirms again the onset of asian inland deserts and monsoon dominate climates by the early miocene

review and revision of cenozoic tropical planktonic foraminiferal biostratigraphy and calibration to the geomagnetic polarity and astronomical time scale planktonic foraminifera are widely utilized for the biostratigraphy of cretaceous and cenozoic marine sediments and are a fundamental component of cenozoic chronostratigraphy the recent enhancements in deep sea drilling recovery multiple coring and high resolution sampling both offshore and onshore has improved the planktonic foraminiferal calibrations to magnetostratigraphy and or modified species ranges this accumulated new information has allowed many of the planktonic foraminiferal bioevents of the cenozoic to be revised and the planktonic foraminiferal calibrations to be reassessed we incorporate these developments and amendments into the existing biostratigraphic zonal scheme in this paper we present an amended low latitude tropical and subtropical cenozoic planktonic foraminiferal zonation we compile 187 revised calibrations of planktonic foraminiferal bioevents from multiple sources for the cenozoic and have incorporated these recalibrations into a revised cenozoic planktonic foraminiferal biochronology we review and synthesize these calibrations to both the geomagnetic polarity time scale gpts of the cenozoic and astronomical time scale ats of the neogene and late paleogene on the whole these recalibrations are consistent with the previous work however in some cases they have led to major adjustments to the duration of biochrons recalibrations of the early middle eocene first appearance datums of globigerinatheka kugleri hantkenina singanoae guembelitrioides nuttalli and turborotalia frontosa have resulted in large changes in the durations of biochrons e7 e8 and e9 we have introduced upper oligocene zone o7 utilizing the biostratigraphic utility of paragloborotalia pseudokugleri for the neogene period major revisions are applied to the fohsellid lineage of the middle miocene and we have modified the criteria for recognition of zones m7 m8 and m9 with additional adjustments regarding the globigerinatella lineage to zones m2 and m3 the revised and recalibrated datums provide a major advance in biochronologic resolution and a template for future progress of the cenozoic time scale

active tectonic features and structural dynamics of the summit area of mt etna italy revealed by soil co2 and soil temperature surveying project cgl2005 07509 cli ministry of education and science of spain dpc ingv project flank istituto nazionale di geofisica e vulcanologia osservatorio etneo sezione di catania

rift zone reorganization through flank instability in ocean island volcanoes an example from tenerife canary islands the relationship between rift zones and flank instability in ocean island volcanoes is often inferred but rarely documented our field data aerial image analysis and 40ar 39ar chronology from anaga basaltic shield volcano on tenerife canary islands support a rift zone flank instability relationship a single rift zone dominated the early stage of the anaga edifice 6 4 5 ma destabilization of the northern sector led to partial seaward collapse at about 4 5 ma resulting in a giant landslide the remnant highly fractured northern flank is part of the destabilized sector a curved rift zone developed within and around this unstable sector between 4 5 and 3 5 ma induced by the dilatation of the curved rift a further rift arm developed to the south generating a three armed rift system this evolutionary sequence is supported by elastic dislocation models that illustrate how a curved rift zone accelerates flank instability on one side of a rift and facilitates dike intrusions on the opposite side our study demonstrates a feedback relationship between flank instability and intrusive development a scenario probably common in ocean island volcanoes we therefore propose that ocean island rift zones represent geologically unsteady structures that migrate and reorganize in response to volcano flank instability

development of sediment landform associations at cold glacier margins dry valleys antarctica hambrey m j fitzsimons s j 2010 development of sediment landform associations at cold glacier margins dry valleys antarctica sedimentology 57 3 857 882 michael hambrey is corresponding author sponsorship marsden fund of new zealand university of otago research committee nerc grant no ner a s 2000 01256

the final phase of dead ice moraine development processes and sediment architecture kotlujokull iceland consecutive phases of de icing of ice cored moraines and the formation of dead ice moraine were monitored over a 4 year period at the terminus of the kotlujokull glacier iceland particularly the transition from partially ice cored moraine with isolated dead ice blocks to the ice free landscape receives attention in this paper in order to link the final melting processes to the architecture of the sedimentary end product in the current humid sub polar climate of south iceland de icing of partially ice cored moraines results chiefly from melting along the bottom surface of ice cores with an annual average rate of 25 cm the final de icing is associated with an interrelated group of re sedimentation processes and surface features series of sinkholes evolve at the toe of dead ice blocks which initiate retrogressive rotational sliding or backslumping of the ice cored slopes and the formation of distinct edges and fractures in the adjacent basins although backslumping is the dominant process in this phase of re sedimentation structures resulting from this process are rarely recognized in the ice free landscape as ice cores gradually diminish the effect of the latest re sedimentation events will overprint or destroy most existing sedimentary characteristics thus in the ice free landscape structures mainly related to the formation of sinkholes and fractures remain imprinted on the sediment succession generally no inversion of the topography occurs during the final phase of de icing the overall topography recognized in the late phase of the fully ice cored terrain is merely lowered and the amplitude of the relief reduced as de icing progresses the sediment architecture of the ice free landscape is characterized by heterogeneous and often slumped diamict sediments with variable thickness and lateral distribution clast orientation is related to the direction of slopes and boulders are found in isolated groups or in linear arrangements

tertiary paleomagnetism of north and south china and a reappraisal of late mesozoic paleomagnetic data from eurasia implications for the cenozoic tectonic history of asia abstract to contribute to the understanding of the cenozoic tectonic history of china and eastern eurasia in general we collected paleomagnetic samples from tertiary rocks in both north and south china our miocene paleomagnetic data for northern china are from four widely separated basalt sections in the inner mongolia autonomous region and shandong province both normal and reversed polarities of the characteristic magnetization are present in the stratigraphie sequence and the mean normal and reversed directions are closely antiparallel to each other the fact that the same characteristic direction was carried by both magnetite and hematite suggests that the hematite was probably formed by auto oxidation processes during primary cooling of the basalts the paleomagnetic data from these four areas also pass a regional generalized fold test the corresponding mean miocene paleomagnetic pole for northern china is longitude 261 6 e latitude 88 3 n a 95 6 4 our early tertiary paleomagnetic results for south china are from two sandstone sections around the city of nanning 22 7 n 108 3 e in guangxi zhuang autonomous region high temperature characteristic directions isolated in 31 samples from five sites pass both tilt and reversal tests the paleomagnetic pole position determined from the five sites lies at longitude 228 0 e latitude 83 6 n a 95 8 5 the tertiary paleomagnetic poles for north and south china are statistically indistinguishable from each other and thus confirm that north and south china were fully assembled at least by the tertiary our new tertiary paleomagnetic data are consistent with the hypothesis that the major continental blocks of north and south china were in the same position as today during the tertiary a critical evaluation and selection of paleomagnetic results from the late jurassic onward for siberia europe and north and south china further corroborate this hypothesis most previously existing jurassic and cretaceous paleomagnetic poles from europe siberia are of uncertain reliability and should not be used for tectonic reconstruction using poles derived from transferring reliable data from other continents we show that the previous paleomagnetic inferences of large eastward displacements between these chinese blocks during the cenozoic are no longer warranted the available paleomagnetic data that meet our acceptance criteria are also of interest concerning the boundary conditions of the propagating extrusion model for asian tectonics additional mesozoic and cenozoic paleomagnetic data from siberia and north and south china are still needed to resolve the smaller second order displacements that appear to characterize the cenozoic tectonic history of this part of asia

flank instability structure of mt etna inferred by a magnetotelluric survey this paper presents a magnetotelluric mt survey of the unstable eastern flank of mt etna we take thirty soundings along two profiles oriented in the n s and nw se directions and from these data recover two 2d resistivity models of the subsurface both models reveal three major layers in a resistive conductive resistive sequence the deepest extending to 14 km bsl the shallow layer corresponds to the volcanic cover and the intermediate conductive layer corresponds to underlying sediments segmented by faults these two electrical units are cut by e w striking faults the third layer basement is interpreted as mainly pertinent to the apennine maghrebian chain associated with sw ne striking regional faults the detailed shapes of the resistivity profiles clearly show that the ne rift is shallow rooted 0 1 km bsl thus presumably fed by lateral dikes from the central volcano conduit the nw se profile suggests by a series of listric faults reaching up to 3 km bsl then becoming almost horizontal toward the se the resistive basement dramatically dips from 3 km to 10 km bsl in correspondence with the timpe fault system several high conductivity zones close to the main faults suggest the presence of hydrothermal activity and fluid circulation that could enhance flank instability our results provide new findings about the geometry of the unstable etna flank and its relation to faults and subsurface structures

magma storage and migration associated with the 2011 2012 el hierro eruption implications for crustal magmatic systems at oceanic island volcanoes 1 starting in july 2011 anomalous seismicity was observed at el hierro island a young oceanic island volcano on 12 october 2011 the process led to the beginning of a submarine nw se fissural eruption at 15 km from the initial earthquake loci indicative of significant lateral magma migration here we conduct a multifrequency multisensor interferometric analysis of spaceborne radar images acquired using three different satellite systems radarsat 2 envisat and cosmo skymed constellation of small satellites for mediterranean basin observation the data fully captures both the pre eruptive and coeruptive phases elastic modeling of the ground deformation is employed to constrain the dynamics associated with the magmatic activity this study represents the first geodetically constrained active magmatic plumbing system model for any of the canary islands volcanoes and one of the few examples of submarine volcanic activity to date geodetic results reveal two spatially distinct shallow crustal magma reservoirs a deeper central source 9 5 4 0 km and a shallower magma reservoir at the flank of the southern rift 4 5 2 0 km the deeper source was recharged explaining the relatively long basaltic eruption contributing to the observed island wide uplift processes and validating proposed active magma underplating the shallowest source may be an incipient reservoir that facilitates fractional crystallization as observed at other canary islands data from this eruption supports a relationship between the depth of the shallow crustal magmatic systems and the long term magma supply rate and oceanic lithospheric age such a relationship implies that a factor controlling the existence depth of shallow crustal magmatic systems in oceanic island volcanoes is the lithosphere thermomechanical behavior

active spreading and regional extension at mount etna imaged by sar interferometry abstract large flank instability has been proposed by most recent authors as a major process in the dynamics of mount etna however several aspects of the models are still disputed such as the boundaries of the moving area and the driving force for the instability in this paper we present synthetic aperture radar interferometric data which allow us to identify two main sectors of active instability where the deformational process differs an eastern sector is bounded to the north by the pernicana provenzana fault to the west by the north rift zone and the south rift zone and to the south by the mascalucia tremestieri trecastagni fault system interferograms provide new data on the activity and extent of the southern boundary which was previously underestimated in this sector the structural features indicate an eastward sliding driven by e w regional extension which can be interpreted as a result of the retreating slab of the ionian subduction a second collapsing sector exists along the southern flank of mount etna where the interferograms show the presence of an active anticlinal ridge this ridge is interpreted as the result of southward gravity spreading over a basal decollement between etna and its plio quaternary basement and the hyblean platform the two sectors first became active in summer 1996 after the beginning of a new cycle of eruptive activity at the summit the activity was ongoing until january 1998 with the deformation rate ranging from 4 6 mm yr for the mascalucia tremestieri trecastagni faults to 12 mm yr for the anticlinal ridge

pb diffusion in zircon abstract chemical diffusion of ti under anhydrous conditions at 1 atm and under fluid present elevated pressure 1 1 1 2 gpa conditions has been measured in natural zircon the source of diffusant for 1 atm experiments was a zro2 tio2 zircon mixture with experiments run in crimped pt capsules diffusion experiments done in the presence of h2o co2 fluid were run in a piston cylinder apparatus using a source of ground tio2 zrsio4 and sio2 with oxalic acid added to produce h2o co2 vapor and partially melt the solid source material yielding an assemblage of rutile zircon melt vapor nuclear reaction analysis nra with the resonant nuclear reaction 48ti p 49v was used to measure diffusion profiles for both sets of experiments the following arrhenius parameters were obtained for ti diffusion normal to cover the temperature range 1350 1550 c at 1 atm d ti 3 33 10 2 exp 754 56 kj mol 1 r t m 2 s 1 ti diffusivities were found to be similar for experiments run under fluid present conditions a fit to all of the data yields the arrhenius relation d 1 34 102 exp 741 46 kj mol 1 rt m2 s 1 these data suggest that zircon should be extremely retentive of ti chemical signatures indicating that the recently developed ti in zircon crystallization geothermometer watson e b harrison t m 2005 zircon thermometer reveals minimum melting conditions on earliest earth science 308 841 844 will be quite robust in preserving temperatures of zircon crystallization titanium diffuses somewhat faster in zircon than larger tetravalent cations u th and hf but considerably more slowly than pb the ree and oxygen hence ti crystallization temperatures may be retained under circumstances when radiometric ages or other types of geochemical information are lost

oligocene miocene magnetic stratigraphy carried by biogenic magnetite at sites u1334 and u1335 equatorial pacific ocean 1 sediments from the equatorial pacific ocean at the integrated ocean drilling program sites u1334 and u1335 record reliable magnetic polarity stratigraphies back to 26 5 ma late oligocene at sedimentation rates usually in the 5 20 m myr range putative polarity subchrons that do not appear in current polarity timescales occur within chrons c5acr c5adn and c5bn 1r at site u1335 and within chrons c6aar 2r c6br c7ar and c8n 1n at site u1334 subchron c5dr 1n 17 5 ma is recorded at both sites supporting its apparent recording in the south atlantic ocean and has an estimated duration of 40 kyr the oligocene miocene calcareous oozes have magnetizations carried by submicron magnetite as indicated by thermal demagnetization of magnetic remanences the anhysteretic remanence to susceptibility ratio and magnetic hysteresis parameters transmission electron microscopy of magnetic separates indicates the presence of low titanium iron oxide magnetite grains with size 50 100 nm and shape similar to modern and fossil bacterial magnetite supporting other evidence that biogenic submicron magnetite is the principal remanence carrier in these sediments in the equatorial pacific ocean low organic carbon burial arrests microbial pore water sulfate reduction thereby aiding preservation of bacterial magnetite

recent high arctic glacial sediment redistribution a process perspective using airborne lidar abstract progressive glacier thinning retreat and mass loss in the high arctic is increasingly exposing forefield sediments to processes of mobilisation and redistribution in this paper we quantify forefield sediment redistribution at midtre lovenbreen svalbard using repeat light detection and ranging lidar surveys conducted in 2003 and 2005 in combination with field based observations average surface lowering of the forefield over the observation period identified from lidar surveys is 0 05 ma 1 and two primary areas of sediment reworking are identified active fluvial incision of proglacial streams by 2 m and lateral moraine downwasting of similar magnitude multivariate analysis of fluvial and climatological field data indicates that observed forefield sediment mobilisation is driven primarily by discharge forcing but with contributions from thermoerosive processes and stochastic autogenic sediment supply during the period of observation disparity between sediment loss in forefield fluvial systems as calculated from lidar data 3000 4000 103 kg and monitoring of fluvial sediment load 1600 3500 103 kg suggests the likely presence of significant quantities of buried ice beneath a thick debris mantle as evidenced by field observations relatively uniform lowering of the moraine crest identified from our repeat lidar surveys indicates thermoerosion of an ice core however simple debris layer thickness modelling indicates an increase in variation of debris layer thickness at lower elevations providing support for the assertion that moraine disintegration is driven by complex combinations of both thermal and mechanical processes this study demonstrates the viability of using lidar in conjunction with field monitoring to better understand sedimentary deglaciation dynamics and processes and also highlights the significance of forefield areas in controlling the sediment yield from deglaciating catchments

lithofacies types and vertical profile models an alternative approach to the description and environmental interpretation of glacial diamict and diamictite sequences abstract increased knowledge of modern glacial depositional environments has resulted in rapidly evolving classifications of glacial tills these are based to a large degree on theoretical considerations of likely depositional processes the classifications are sophisticated and more advanced than the establishment of simple field criteria whereby individual till facies can be identified in quaternary and pre quaternary successions this situation is compounded in many quaternary terrains by the continued description of tills in terms of laboratory derived analytical data only reflecting a traditional interest in stratigraphic correlation rather than reconstruction of depositional environment detailed sedimentological logging of lithofacies is rarely undertaken there is thus considerable confusion as to what is being described or sampled when analytical data are presented for many pleistocene tills the same remarks apply to pre pleistocene tillites a lithofacies code is presented here for the rapid description and visual appraisal of field sequences or drill cores containing unconsolidated diamicts or lithified diamictites the term till is not used as it has a strict genetic definition referring to direct aggregation and deposition by glacier ice use of a four part code in conjunction with codes already published for fluvial sediments allows fundamental field properties to be depicted independent of genetic terminology and provides a firm basis for subsequent environmental interpretation and analytical work the value of this approach is illustrated by comparing a representative suite of vertical profiles of diamict assemblages deposited by modern grounded glaciers with a classic late pleistocene glacigenic sequence at scarborough bluffs ontario

miocene magnetostratigraphy from equatorial pacific sediments odp site 1218 leg 199 pliocene and miocene magnetostratigraphy from odp site 1218 equatorial pacific has been obtained by measurements made on u channel samples augmented by about 50 discrete samples u channel samples were measured at 1 cm intervals and stepwise demagnetized in alternating fields up to a maximum peak field of 80 mt the component magnetization directions were determined by principal component analysis for demagnetization steps in the 20 60 mt peak field range a relatively small number of discrete samples were subject to both thermal and alternating field af demagnetization and gave results compatible with u channel measurements magnetostratigraphy from u channel samples are compared with shipboard data that were based on blanket demagnetization at peak af fields of 20 mt u channel measurements add more detail to the magnetostratigraphic record and allow identification of thin polarity zones especially in the upper part of the section were the sedimentation rates are very low 2 m myr the component magnetization directions determined from u channel measurements also gave more reliable and precise estimates of inclination paleolatitude the magnetostratigraphy from site 1218 can be unambiguously correlated with the reference geomagnetic polarity time scale and gives a means of dating the sedimentary sequence both miocene pliocene and oligocene miocene stage boundaries were easily identified from the magnetostratigraphic record although calculation of paleomagnetic poles is hindered by the low precision of the cores azimuthal orientation the data from both u channel and discrete samples allow determination of the paleolatitude of the site through time with good precision paleomagnetic data indicate that the paleolatitude of site 1218 has increased form nearly equatorial latitude in the oligocene to

sublimation and aeolian sand movement from a frozen surface experimental results from presqu ile beach ontario abstract recent aeolian literature has indicated that sand movement can and does take place on frozen surfaces the winter aeolian process is influenced by the pore ice which binds the sand grains together and increases the surface resistance to wind action sublimation of the frozen moisture provides loose grains of sand which subsequently can be entrained by the wind field experiments carried out on the presqu ile beach ontario in the 1992 1993 winter provide some data on variables which affect sand loss from frozen surfaces because of sublimation sand moisture content determines the resistivity of the surface to sublimation induced sand loss frozen surfaces with higher moisture contents experience less sand loss the existing literature has indicated that temperature plays an important role in the occurrence of sublimation higher temperatures i e temperatures which are closer to 0 c result in higher rates of sublimation however the presqu ile experiments show that wind speed is more strongly correlated with sublimation induced particle loss than temperature or relative humidity higher wind speeds allow sand from the surface and sublimation produced water vapour to be removed from the area thus providing an incentive for further sublimation and sand loss to take place information on the variables which affect sublimation induced sand loss from frozen surfaces can be used to increase understanding of the processes involved in sand movement on frozen surfaces under subzero temperatures

intrusive mechanism of the 2002 ne rift eruption at mt etna italy inferred through continuous microgravity data and volcanological evidences 1 in october 2002 a new eruption began at etna lava flows were issued from two different fissure systems on the ne and s flanks of the volcano a continuous microgravity sequence acquired at a station on the n slope 2800 m a s l shows a marked decrease about 400 gal in less than one hour about 4 hours before lava was first emitted from the eruptive fissures along the ne rift this anomaly reversed soon afterward at a high rate the strong gravity decrease is interpreted as the opening by external forces of a shallow fracture system 1 km w of the gravity station magma from the central conduit entered the new fracture system passively and propagated through it towards lower portions of the ne rift both the arrangement of the new fracture system and the eruptive dynamics are in keeping with the inferred intrusive mechanism

some mechanical aspects of pingo growth and failure western arctic coast canada many closed system pingos are underlain by sub pingo water lenses and the same is probably true of numerous open system pingos in the early growth stage the bending of the frozen overburden of a pingo by a sub pingo water lens can be compared to the bending of a thin elastic plate although the assumptions of elastic plate theory do not apply fully to a growing pingo because time dependent plastic and creep deformation are involved the application of elastic plate theory nevertheless helps to explain the peripheral normal faulting and spring flow of pingos summit failure the ease with which elongated pingos appear to collapse and the changing roles played by the radius and overburden thickness of pingos from early growth to the cessation of growth

paleomagnetism of the early miocene kani group in southwest japan and its implication for the opening of the japan sea paleomagnetic directions of a volcanic and sedimentary sequence of the kani basin ranging from 22 to 15 ma show a clockwise declination shift of about 50 degree this result implies that detectable rotation of southwest japan did not occur in this period but after 15 ma the initial opening of the japan sea before 15 ma might have caused a southeastward translation of southwest japan which was then followed by clockwise rotation between 16 and 14 ma

controlled moraines origins characteristics and palaeoglaciological implications abstract controlled moraines are supraglacial debris concentrations that become hummocky moraine upon de icing and possess clear linearity due to the inheritance of the former pattern of debris rich folia in the parent ice linearity is most striking wherever glacier ice cores still exist but it increasingly deteriorates with progressive melt out as a result moraine linearity has a low preservation potential in deglaciated terrains but hummocky moraine tracts previously interpreted as evidence of areal stagnation may instead record receding polythermal glacier margins in which debris rich ice was concentrated in frozen toe zones recent applications of modern glaciological analogues to palaeoglaciological reconstructions have implied that a controlled moraine development can be ascribed to a specific process e g englacial thrusting or supercooling and b controlled moraine preservation potential is good enough to imply the occurrence of the specific process in former glacier snouts e g ancient polythermal or supercooled snouts these assumptions are tested using case studies of controlled moraine construction in which a wide range of debris entrainment and debris rich ice thickening mechanisms are seen to produce the same geomorphic features polythermal conditions are crucial to the concentration of supraglacial debris and controlled moraines in glacier snouts via processes that are most effective at the glacier permafrost interface end moraines lie on a process form continuum constrained by basal thermal regime the morphological expression of englacial structures in controlled moraine ridges is most striking while the moraines retain ice cores but the final deposits landforms tend to consist of discontinuous transverse ridges with intervening hummocks preserving only a weak impression of the former englacial structure these are arranged in arcuate zones of hummocky moraine up to 2 km wide containing ice walled lake plains and lying down flow of streamlined landforms produced by warm based ice a variety of debris entrainment mechanisms can produce the same geomorphic signature spatial and temporal variability in process form relationships will lead to the sequential development of different types of end moraines during the recession of a glacier or ice sheet margin

seismo tectonic behavior of the pernicana fault system mt etna a gauge for volcano flank instability 1 flank instability at basaltic volcanoes is often related to repeated dike intrusions along rift zones and accompanied by surface fracturing and seismicity these processes have been mostly studied during specific events and the lack of longer term observations hinders their better understanding here we analyze 20 years of deformation of the pernicana fault system pfs the key structure controlling the instability of the eastern flank of mt etna we exploit east west and vertical components of mean deformation velocity as well as corresponding time series computed from ers envisat 1992 2010 and cosmo skymed 2009 2011 satellite radar sensors via synthetic aperture radar interferometry techniques we then integrate and compare this information with field seismic and leveling data collected between 1980 and 2012 we observe transient displacements accompanied by seismicity overprinted on a long term background eastward motion 2 cm yr in the last decades these transient events were preceded by a constant amount of accumulated strain near the pfs the time of strain accumulation varies between a few years and a few decades also depending on magma emplacement within the nearby north east rift which may increase the strain along the pfs these results suggest that the amount of deformation near the pfs may be used as a gauge to forecast the occurrence of instability transients on the eastern flank of etna in this context the pfs may provide an ideal small scale structure to test the relations between strain accumulation stress loading and seismic energy release

glacier retreat and landform production on an overdeepened glacier foreland the debris charged glacial landsystem at kviarjokull iceland glacier recession and landform development in a debris charged glacial landsystem characterized by an overdeepening is quantified using digital photogrammetry digital elevation model dem construction and mapping of the icelandic glacier kviarjokull for the period 1945 2003 melting of ice cores is recorded by surface lowering rates of 0 8 m yr 1 1945 1964 0 3 m yr 1 1964 1980 0 015 m yr 1 1980 1998 and 0 044 m yr 1 1998 2003 the distribution preservation of pushed and stacked ice cored moraine complexes are determined by the location of the long term glacial drainage network in combination with retreat from the overdeepening into which glacifluvial sediment is being directed and where debris rich ice masses are being reworked and replaced by esker networks produced in englacial meltwater pathways that bypassed the overdeepening and connected to outwash fans prograding over the snout recent accelerated retreat of kviarjokull potentially due to increased mass balance sensitivity has made the snout highly unstable especially now that the overdeepening is being uncovered and the snout flooded by an expanding pro glacial and partially supraglacial lake this case study indicates that thick sequences of debris charged basal ice controlled moraine have a very low preservation potential but ice cored moraine complexes can develop into hummocky moraine belts in de glaciated terrains because they are related to the process of incremental stagnation which at kviarjokull has involved periodic switches from transport dominant to ablation dominant conditions glacier recession is therefore recorded temporally and spatially by two suites of landforms relating to two phases of landform production which are likely typical for glaciers occupying overdeepenings an early phase of active temperate recession recorded by push moraines and lateral moraines and unconfined pro glacial meltwater drainage and a later phase of incremental stagnation and pitted outwash head development initiated by the increasing topographic constraints of the latero frontal moraine arc and the increasing importance of the overdeepening as a depo centre copyright 2012 john wiley sons ltd

paleoposition of southwest japan at 16 ma implication from paleomagnetism of the miocene ichishi group abstract new paleomagnetic data from shallow marine sediments of the ichishi group suggest a clockwise tectonic rotation of southwest japan in the middle miocene samples have been collected from mud or tuff layers at 17 sites stability of remanent magnetization has been examined by using alternating field and thermal demagnetization the polarity sequence composed of four normal and seven reversed polarity sites is correlated to polarity epoch 16 15 2 17 6 ma based on micropaleontological assignment of the upper ichishi group to blow s zone n8 the mean paleomagnetic direction of the 11 sites shows an anomalous declination toward the northeast this result suggests that southwest japan was subjected to a clockwise rotation through 45 since 16 ma the clockwise rotation can be explained by the drift of southwest japan associated with the spreading of the japan sea during the middle miocene

basal ice sequences in antarctic ice stream exposure of past hydrologic conditions and a principal mode of sediment transfer 1 the brightness distribution of sequentially extracted borehole camera imagery shows two distinct sequences of basal ice in kamb ice stream the upper sequence 7 3 m comprises clear ice and layers with dispersed and stratified debris the lower sequence 8 2 m consists of accretion ice with alternating layers of stratified and solid debris the two sequences have volumetric debris contents of about 5 and 20 respectively we infer that the upper sequence formed in a tributary where subglacial meltwater was abundant and that the lower sequence formed on the siple coast plain where basal freezing currently dominates the basal thermal regime the basal ice layer contains the equivalent of 2 1 0 4 m of frozen sediment the high volume of sediment is a result of debris rich layers interpreted to have formed by accretion in the stagnant phase of ice stream on off cycles fast ice streaming punctuated by entrainment of debris during stagnation episodes is consistent with inferred past flow of adjacent ice streams and geologic features in the ross sea our results show that sediment wedges near grounding lines may form by melt out of basal ice debris this is different from previous studies where it was assumed that sediment transfer occurs through sediment deformation within layers of subglacial till cumulative freezing in recurring ice stream cycles shows that entrainment of sediment by basal freeze on is an important erosion mechanism and that high sediment fluxes can occur when ice streams override coulomb plastic substrates

the role of the pernicana fault system in the spreading of mt etna italy during the 2002 2003 eruption flank instability and collapse are observed at many volcanoes among these mt etna is characterized by the spreading of its eastern and southern flanks the eastern spreading area is bordered to the north by the e w trending pernicana fault system pfs during the 2002 2003 etna eruption ground fracturing along the pfs migrated eastward from the ne rift to as far as the 18 km distant coastline the deformation consisted of dextral en echelon segments with sinistral and normal kinematics both of these components of displacement were one order of magnitude larger 1 m in the western previously known portion of the pfs with respect to the newly surveyed 9 km long eastern section 0 1 m this eastern section is located along a pre existing but previously unknown fault where displaced man made structures give overall slip rates 1 1 9 cm year only slightly lower than those calculated for the western portion 1 4 2 3 cm year after an initial rapid motion during the first days of the 2002 2003 eruption movement of the western portion of the pfs decreased dramatically while parts of the eastern portion continued to move these data suggest a model of spreading of the eastern flank of etna along the pfs characterized by eruptions along the ne rift instantaneous short lived meter scale displacements along the western pfs and more long lived centimeter scale displacements along the eastern pfs the surface deformation then migrated southwards reactivating one after the other the nnw sse trending timpe and trecastagni faults with displacements of 0 1 and 0 04 m respectively these structures along with the pfs mark the boundaries of two adjacent blocks moving at different times and rates the new extent of the pfs and previous activity over its full length indicate that the sliding eastern flank extends well below the ionian sea the clustering of seismic activity above 4 km b s l during the eruption suggests a deep decollement for the moving mass the collected data thus suggests a significant movement volume 1 100 km3 of the eastern flank of etna both on shore and off shore

the basal ice layer of glaciers and ice sheets abstract in many glaciers and ice sheets there is a basal ice layer bil in which the ice is conditioned primarily by processes operating at the bed the bil is chemically and physically distinctive and is characterised by a component of basally derived sediment the bil is a rheological control on ice sheet dynamics an indicator of subglacial conditions and processes an agent of subglacial geologic processes the source of a substantial proportion of glacial sediments a limit to the downward extension of the climate record from deep ice cores if debris characteristics of the bil are preserved in glacial sediments former glacier conditions can be inferred analysis of stable isotopes gas and cation composition ice crystallography debris composition and structural glaciology has elucidated many mechanisms for bil formation common elements can be identified from a range of locations key issues are entrainment of ice and debris from the bed formation of new ice metamorphism of existing ice in the bil and thickening of the bil by deformation a distinction can be made between basal ice formed by accretion of material from the bed stratified facies and basal ice formed by metamorphic processes within the ice close to the bed dispersed facies

age of the n7 n8 m4 m5 planktonic foraminifera zone boundary constraints from the zircon geochronology and magnetostratigraphy of early miocene sediments in ichishi japan abstract the age assigned to the miocene n7 n8 m4 m5 planktonic foraminifera zone boundary is markedly different from the astronomically tuned neogene time scales published in 2004 atnts2004 and 2012 atnts2012 this difference is primarily because of the lack of reliable assignment of the zone boundary to magnetostratigraphy which needs to be resolved for the better refinement of the geologic time scale our previous biostratigraphic results from an onland sedimentary sequence of the upper ichishi group in central japan allow location of the stratigraphic position of the lowest occurrence datum lod of praeorbulina sicana a key planktonic foraminifera species for defining the n7 n8 m4 m5 zone boundary in this study we performed laser ablation multiple collector inductively coupled plasma mass spectrometry u pb dating on zircons from two felsic tuff beds in the ichishi sequence the age of the zone boundary is approximated by a u pb age of 17 03 0 11 ma for a tuff bed 2 m above the boundary we also conducted a magnetostratigraphic analysis in which site mean characteristic remanent magnetization directions were determined for 19 sites and showed a reverse normal reverse r n r stratigraphic change in polarity the n7 n8 m4 m5 zone boundary is within the upper reverse polarity zone the r n r sequence can be correlated with a stratigraphic portion corresponding to chrons c5dr c5dn c5cr hence the age of the zone boundary is within chron c5cr our results are thus compatible with the age 16 97 ma assigned to the boundary in atnts2004 rather than atnts2012 and should be considered when the neogene time scale is updated a normal polarity subzone found in the upper reverse polarity zone can also be dated at 17 0 ma and is probably correlated with a short normal polarity episode in chron c5cr in terms of tectonic rotation the site mean magnetization directions determined in this study suggest an 35 clockwise rotation in ichishi with respect to the north china block in the asian continent since 17 2 ma the upper boundary age of chron c5dn clockwise rotation of southwest japan which occurred in association with backarc opening of the japan sea was probably in progress during deposition of the upper ichishi group sediments

remote sensing of volcanoes and volcanic processes integrating observation and modelling introduction volcanoes are often remote and have footprints that may extend across many hundreds or thousands of square kilometres they are generally inaccessible during eruption and may continue to be inaccessible for extended periods of time after eruption while their products can be scattered or dispersed over regional or global scales consequently since direct measurement can only provide us with part of the picture of many volcanic processes remote sensing is now playing an increasingly important role in advancing understanding of the science underlying volcanic behaviour on this planet and beyond e g mouginis mark et al 2000 sparks et al 2012 satellite airborne and ground based remote sensing are increasingly vital tools for monitoring active or potentially active volcanoes and assessing their likely real time or time averaged impact fig 1 at the same time the synoptic scale surveys that are often well suited to remote sensing techniques allow us to address questions about the fundamental processes that control volcano behaviour in a way that is not necessarily possible from individual case studies new research is often driven by technological advancements in the development of novel sensors or launching of new platforms meaning that the space agencies are increasingly involved in identifying scientific questions and priorities e g ferruci et al 2012 multiple and complementary data streams are increasingly being used both to monitor active volcanoes and advance volcanological science the key geophysical parameters that comprise monitoring data streams typically include the categories of i seismicity ii surface deformation iii thermal measurements and iv gas flux and composition data as major components while measurements of seismicity remain the domain of ground based seismometers remote sensing techniques have made major contributions in each of the others this special publication volume is concerned with the use of remote sensing at volcanoes it is split into three parts roughly arranged from the subsurface to the surface and then further afield as volcanic products are injected and dispersed into the atmosphere the papers span a range of applications of remote sensing techniques to monitor and understand a surface deformation b surface thermal anomalies and c gas fluxes as well as tracking ash and gas plumes from eruptions to gain insights into the extent of a volcano s impacts volcanology is driven in part by the operational concerns surrounding volcano monitoring and hazard and crisis management but the goal of volcanological science is at its heart to understand the processes that underlie volcanic activity this special publication is also concerned with how we go from observations to this deeper understanding including the progress that can be made by integrating observations and modelling while this volume focuses mainly on satellite based remote sensing integrating datasets from different platforms is also of vital importance and so papers on airborne remote sensing and measurement from both manned and unmanned aircraft are also included

review of ten years of volcano deformations recorded by the ground based insar monitoring system at stromboli volcano a tool to mitigate volcano flank dynamics and intense volcanic activity abstract stromboli volcano southern italy is one of the most monitored volcano in the world with a surveillance network that includes a permanently sited ground based sar interferometer gbinsar this work is the review of the gbinsar data gained from the last decade of monitoring activity the analysis of the entire dataset of gbinsar measurements allowed the assessment of the deformation field of the northern part of the summit crater area and the sciara del fuoco depression in detail the main displacements recognized can be related to different factors 1 the inflation deflation respectively immediately before and after each new effusive event 2 the bulging of localized sectors of the volcano involved in the vent opening 3 the gravitational sliding of the sciara del fuoco infill 4 the movement of lava flows accelerations in this sector are related to sheet intrusions while the possibility of vent opening associated with small sliding or catastrophic flank failure are related to highly overpressurized sheets able to produce high displacement rate in the sciara del fuoco in the summit crater area the increases in the displacement rate are related to the pressurization of the shallow conduit system as the consequence of the variation in the magma level magmastatic pressure or to the lateral magma migration lateral conduit expansion or dike intrusion in response to the increase of the overpressure component fluctuations in the displacement rate in the summit crater area can be related to the magma overturning within the conduit with the increases in displacement rate during the upwelling of less dense magma while displacement rate decreases as the degassed magma column is pushed out from the conduit lava flows or overflows instead the decrease in the displacement rate without coeval lava outpouring could be related to the sink of the degassed magma due to density contrast between the gas poor and the gas charged magmas using the displacement rate in the summit crater area as a proxy for the variation in the pressure condition in conduit both magmastatic and overpressure components thresholds for the crises characterized by the occurrence of overflows eventually associated with major explosions and flank effusions eventually associated with paroxysmal explosions are identified small conduit overpressure will produce overflows sometimes associated with crater rim collapses while large magma overpressure will laterally expand the conduit forming ne sw striking sheets feeding eruptive vents at the base of the summit crater area and within the sciara del fuoco generating conditions of instability that can evolve into catastrophic collapse of the instable flank

formation of glaciolacustrine late pleistocene end moraines in the tasman valley new zealand abstract detailed examination of the tekapo formation in the tasman valley new zealand has identified 20 facies and five facies associations these associations are delta foresets and bottomsets sediment density flows ice contact lake sediments with ice rafted debris and resedimentation deposits and outwash gravels interpretation of the sediment landform associations informed by observations at modern glacier termini suggests that the late pleistocene tekapo formation moraines have been formed by downwasting of a more expanded tasman glacier during the early stages of glacier retreat ponds on the glacier surface develop into thermokarst lakes which enlarge and coalesce to form a large supraglacial lake continued downwasting causes the lake outlet river to entrench into the impounding latero frontal ice cored moraine lowering the lake level this exposes lake bottom sediments and forms shorelines on the proximal slopes of the ice cored moraine as the ice cored moraine melts these lake sediments are deformed and deposited against the mt john moraine the observations and interpretations reported here suggest the late pleistocene end moraine is a constructional feature not a structural glaciotectonic feature as suggested by previous studies

how do volcanic rift zones relate to flank instability evidence from collapsing rifts at etna 1 volcanic rift zones characterized by repeated dike emplacements are expected to delimit the upper portion of unstable flanks at basaltic edifices we use nearly two decades of insar observations excluding wintertime acquisitions to analyze the relationships between rift zones dike emplacement and flank instability at etna the results highlight a general eastward shift of the volcano summit including the northeast and south rifts this steady state eastward movement 1 2 cm yr is interrupted or even reversed during transient dike injections detailed analysis of the northeast rift shows that only during phases of dike injection as in 2002 does the rift transiently becomes the upper border of the unstable flank the flank s steady state eastward movement is inferred to result from the interplay between magmatic activity asymmetric topographic unbuttressing and east dipping detachment geometry at its base this study documents the first evidence of steady state volcano rift instability interrupted by transient dike injection at basaltic edifices

discriminating glacier thermal and dynamic regimes in the sedimentary record abstract this paper provides a description and evaluation of the sedimentary facies and environments associated with a range of glacier thermal and dynamic regimes with additional consideration given to the tectonic context new and previously published data are evaluated together and are presented from modern terrestrial and marine glacial sedimentary environments in order to identify a set of criteria that can be used to discriminate between different glacier thermal regimes and dynamic styles in the sedimentary record sedimentological data are presented from a total of 28 glaciers in 11 geographical areas that represent a wide range of contemporary thermal dynamic and topographic regimes in the context of landsystems representatives from terrestrial environments include temperate glaciers in the european alps patagonia new zealand the cordillera blanca peru cold glaciers in the dry valleys of antarctica and the antarctic peninsula region and polythermal valley glaciers in svalbard northern sweden the yukon and the khumbu himal nepal the glaciomarine environment is illustrated by data from cold and polythermal glacier margins on the east antarctic continental shelf and from a polythermal tidewater glacier in svalbard along with general observations from temperate glaciers in alaska these data show that temperate glacial systems particularly in high relief areas are dominated by rockfall and avalanche processes although sediments are largely reworked by glaciofluvial processes debris in polythermal glaciers is both thermally and topographically influenced in areas of moderate relief debris is mainly of basal glacial origin and the resulting facies association is dominated by diamicton in high relief areas such as the himalaya the debris load in polythermal glaciers is dominated by rockfall and avalanche inputs resulting in extensive accumulations of sandy boulder gravel cold glaciers are dominated by basal debris entrainment but sediments are little modified from the source materials which are typically sandy boulder gravel from older till and sand from glaciofluvial glaciolacustrine and aeolian sources similar facies associations but with different facies geometry and thickness occur in equivalent glaciomarine settings application of these concepts can aid the interpretation of glacier thermal regime and hence palaeoclimate in quaternary and ancient glacial systems

an assessment of evidence for pingos on mars using hirise pingos are small hills with cores of ice formed by injection and freezing of pressurized water the possibility of pingos on mars is of particular interest because of the associated implications for liquid water we have systematically searched for candidate pingos using images from the high resolution imaging science experiment hirise camera since pingos are expected to develop surface fractures due to extension of the frozen ground over the ice core we have searched for fractured features and identified a variety of mounds these features are confined to the martian mid latitudes in the bands where gullies are also most common the observed fractured mounds have a variety of morphologies and are likely of multiple origins isolated fractured mounds found on the floors of gullied craters in the southern hemisphere match the general morphologic characteristics of terrestrial pingos and are the best candidates for martian pingos but there is currently no direct evidence for presence of ice cores and it is difficult to produce the necessary water volumes so these features should still be interpreted with caution other fractured mounds appear more likely to be erosional remnants of an unusual mantling layer or possibly thermokarst structures flat topped mounds in utopia have some characteristics fracture pattern and latitudinal distribution consistent with pingos but differ in other aspects such as shape and setting while we do not rule out a pingo origin we prefer an erosional model for these enigmatic features

control of rock rheology on deformation style and slip rate along the active pernicana fault mt etna italy abstract the already known part of the active left lateral strike slip pernicana fault on the eastern flank of mt etna volcano has a holocene high slip rate of 1 5 2 7 cm yr but its surface trace abruptly disappears eastward approaching the lower slope of the volcano using geological geomorphological and structural surveys we found that the pernicana deformation zone extends 8 km further to the east beyond this point through a different mechanism as the thickness of the volcanic pile decreases the single e w to ese striking main fault plane gives way to a set of faults arranged in a splay structure which partitions the fault motion here slip rates are 0 4 to 1 4 cm yr on each fault further east where the lava succession is very thin and unfaulted we suggest that lavas are decoupled from plastic deforming sub etnean clay deposits which absorb the strain or that lavas have a too low mass to slide on the very lowest slope of the volcano i e further east lavas are once again thicker and the pernicana deformation zone behaves at the surface once again in a brittle manner locally known as the fiumefreddo fault with a low slip rate of

sedimentary facies and landform genesis at a temperate outlet glacier soler glacier north patagonian icefield glasser n f hambrey m j 2002 sedimentary facies and landform genesis at a temperate outlet glacier soler glacier north patagonian icefield 49 1 43 64

what happens to in soil radon activity during a long lasting eruption insights from etna by multidisciplinary data analysis we analyze short to long term changes from days to months in radon rn activity measured nearby 2 km the eruptive fractures that fed a lava effusion at mt etna italy between 13 may 2008 and 6 july 2009 the n120 140 e eruptive fractures opened between 3050 and 2620 m above sea level before a dike forming intrusion fed the 14 month long lava emission our high rate data streams include rn ambient parameters barometric pressure and soil temperature and seismic data earthquakes and volcanic tremor recorded from january 2008 to july 2009 the analysis highlights repeated episodes of rock fracturing related to seismic swarms and vigorous gas pulses and peak values in rn emissions maximum 4 1x105 bq m3 on 16 november 2008 which we interpreted in a conceptual model as the response to inputs from the magmatic system during the eruption this multidisciplinary study i provides evidence of a close relationship between rn emission at a fumarole near the summit active craters and local earthquakes and ii enables exploring the important role of the volcanic source on the temporal development of the rn flux which may account for the much higher 94 m day ascent speed of the rn carrier vapor than diffusion the close location of rn probes to the active conduits along with the application of our multidisciplinary approach may shed new light on the internal dynamics of other active volcanoes worldwide

de icing progression of ice cored moraines in a humid subpolar climate kotlujokull iceland modes and rates of de icing ice cored moraines under humid subpolar conditions have been determ ined for two dead ice fields of different age representing a mature and a final stage of collapse in the kotlujokull terminus region south iceland the melting processes considered are backwasting defined as the lateral retreat of near vertical ice walls or steep ice cored slopes and downwasting defined as the thinning of the ice core by melting along the top and bottom surfaces in the mature stage of collapse where there is less than 1 m of sediment cover major faces of ice exposed for rapid melting are ordinarily significant and long lived due to intense precipitation in this fully ice cored terrain the predominating processes are backwasting of exposed ice walls and downwasting by bottom melt each contributing to the annual surface lowering of about 0 5 m or 35 the total annual surface lowering melt rate due to all processes averages 1 4 m in those parts of the fully ice cored dead ice field

detachment depth revealed by rollover deformation an integrated approach at mount etna this work was partially funded by ingv and the dpc ingv project flank and partially by the asi srv project

anatomy of an unstable volcano from insar multiple processes affecting flank instability at mt etna 1994 2008 1 volcano deformation may occur under different conditions to understand how a volcano deforms as well as relations with magmatic activity we studied mt etna in detail using interferometric synthetic aperture radar insar data from 1994 to 2008 from 1994 to 2000 the volcano inflated with a linear behavior the inflation was accompanied by eastward and westward slip on the eastern and western flanks respectively the portions proximal to the summit showed higher inflation rates whereas the distal portions showed several sectors bounded by faults in some cases behaving as rigid blocks from 2000 to 2003 the deformation became nonlinear especially on the proximal eastern and western flanks showing marked eastward and westward displacements respectively this behavior resulted from the deformation induced by the emplacement of feeder dikes during the 2001 and 2002 2003 eruptions from 2003 to 2008 the deformation approached linearity again even though the overall pattern continued to be influenced by the emplacement of the dikes from 2001 to 2002 the eastward velocity on the eastern flank showed a marked asymmetry between the faster sectors to the north and those largely inactive to the south in addition from 1994 to 2008 part of the volcano base south west and north lower slopes experienced a consistent trend of uplift on the order of 0 5 cm yr this study reveals that the flanks of etna have undergone a complex instability resulting from three main processes in the long term 103 104 years the load of the volcano is responsible for the development of a peripheral bulge in the intermediate term 101 years observed from 1994 to 2000 inflation due to the accumulation of magma induces a moderate and linear uplift and outward slip of the flanks in the short term 1 year observed from 2001 to 2002 the emplacement of feeder dikes along the ne and south rifts results in a nonlinear focused and asymmetric deformation on the eastern and western flanks deformation due to flank instability is widespread at mt etna regardless of volcanic activity and remains by far the predominant type of deformation on the volcano

the spectrum of persistent volcanic flank instability a review and proposed framework based on kīlauea piton de la fournaise and etna abstract persistent motion of the south flank of k lauea volcano hawai i has been known for several decades but has only recently been identified at other large basaltic volcanoes namely piton de la fournaise la reunion and etna sicily thanks to the advent of space geodetic techniques nevertheless understanding of long term flank instability is based largely on the example of k lauea despite the large differences in the manifestations and mechanisms of the process when viewed through a comparative lens for example the rate of flank motion at k lauea is several times that of etna and piton de la fournaise and is accommodated on a slip plane several km deeper than is probably present at the other two volcanoes gravitational spreading also appears to be the dominant driving force at k lauea given the long term steady motion of the volcano s south flank regardless of eruptive intrusive activity whereas magmatic activity plays a larger role in flank deformation at etna and piton de la fournaise k lauea and etna however are both characterized by heavily faulted flanks while piton de la fournaise shows little evidence for flank faulting a helpful means of understanding the spectrum of persistent flank motion at large basaltic edifices may be through a framework defined on one hand by magmatic activity which encompasses both magma supply and edifice size and on the other hand by the structural setting of the volcano especially the characteristics of the subvolcanic basement or subhorizontal intravolcanic weak zones a volcano s size and magmatic activity will dictate the extent to which gravitational and magmatic forces can drive motion of an unstable flank and possibly the level of faulting of that flank while the volcano s structural setting governs whether or not a plane of weakness exists beneath or within the edifice and can facilitate flank slip considering persistent flank instability using this conceptual model is an alternative to using a single volcano as a type example especially given that the example is usually k lauea which defines an extreme end of the spectrum and can provide a basis for understanding why flank motion may or may not exist on other large basaltic volcanoes worldwide

the evolution of ace lake antarctica determined from sedimentary diatom assemblages abstract the sediments in ace lake in the vestfold hills east antarctica contain a continuous sequence of diatom frustules that record the lake s history since its formation during the retreat of continental ice more than 9200 years ago frustules from six indicator groups pinnularia microstauron nitzschia cylindrus nitzschia curta eucampia antarctica a freshwater stauroneis species and several centric species in a sediment core were used to determine the sequence of the lake s evolution the history of the lake falls into five stages ace lake began as a marine inlet influenced by dynamic mixing of ocean and meltwater inputs as the ice sheet retreated isostatic uplift isolated the lake allowing it to be flushed by meltwater input from the retreating ice sheet over the course of 800 years 9200 8400 14c yr b p the lake became meromictic supporting a freshwater diatom assemblage approximately 6700 years ago coinciding with antarctic sea level maxima diatom assemblages indicate that seawater flooded over the sill into ace lake disturbing the freshwater meromixis the sediments in this period were laminated and contained elemental sulphur suggesting that the marine input was limited in extent and energy approximately 5500 years ago this marine input ceased and the lake again became a meromictic basin which stabilised over 1700 years to become the lake that it is today and has been with little change for about the past 4000 years