gravity field of the moon from the gravity recovery and interior laboratory grail mission spacecraft to spacecraft tracking observations from the gravity recovery and interior laboratory grail have been used to construct a gravitational field of the moon to spherical harmonic degree and order 420 the grail field reveals features not previously resolved including tectonic structures volcanic landforms basin rings crater central peaks and numerous simple craters from degrees 80 through 300 over 98 of the gravitational signature is associated with topography a result that reflects the preservation of crater relief in highly fractured crust the remaining 2 represents fine details of subsurface structure not previously resolved grail elucidates the role of impact bombardment in homogenizing the distribution of shallow density anomalies on terrestrial planetary bodies

plateau icefields as contributing areas to valley glaciers and the potential impact on reconstructed elas a case study from the lyngen alps north norway

the lunar wide effects of basin ejecta distribution on the early megaregolith the lunar surface is marked by at least 43 large and ancient impact basins each of which ejected a large amount of material that modified the areas surrounding each basin we present an analysis of the effects of basin formation on the entire lunar surface using a previously defined basin ejecta model our modeling includes several simplifying assumptions in order to quantify two aspects of basin formation across the entire lunar surface 1 the cumulative amount of material distributed across the surface and 2 the depth to which that basin material created a well mixed megaregolith we find that the asymmetric distribution of large basins across the moon creates a considerable nearside farside dichotomy in both the cumulative amount of basin ejecta and the depth of the megaregolith basins significantly modified a large portion of the nearside while the farside experienced relatively small degrees of basin modification following the formation of the large south pole aitken basin the regions of the moon with differing degrees of modification by basins correspond to regions thought to contain geochemical signatures remnant of early lunar crustal processes indicating that the degree of basin modification of the surface directly influenced the distribution of the geochemical terranes observed today additionally the modification of the lunar surface by basins suggests that the provenance of lunar highland samples currently in research collections is not representative of the entire lunar crust identifying locations on the lunar surface with unique modification histories will aid in selecting locations for future sample collection

evidence for two zones of debris entrainment beneath the greenland ice sheet investigation of the ice debris and stable isotope characteristics of basal ice exposed at the margin of the greenland ice sheet provides a means of testing and refining models of ice sheet erosion and deposition the basal ice exposed at the ice sheet margin gives evidence of the processes operating at the bed at different locations which can be used to constrain theoretical models predicting varying basal conditions1 2 improved understanding of the effects of isotope fractionation in hydrogen and oxygen caused by freezing processes at the bed which modify the isotope characteristics of the basal ice layers enables us to report evidence of two separate zones of debris entrainment beneath the ice sheet

weertman regelation multiple refreezing events and the isotopic evolution of the basal ice layer a simple model is developed to s imulate the isotopic fractionation which accompanies weertman regelation at the bed of temperate based glaciers the fractionation equations of jouzel and souchez 1 982 are applied to multiple refreezing events over measured glacier bed profiles and mass balance is maintained as the basal ice and meltwater produced at one bedrock hummock enter the next s imulation results indicate that undeformed regelation ice layers are on the order of millimetres to centimetres thick often being completely melted at the stoss face of certain hummocks and exceptionally reaching a thickness in excess of 1 0 cm neither the internal morphology nor the isotopic composition of these layers is constant but both vary down glacier in accordance with bedrock configuration a glacier wide fractionation process is identified whereby heavy isotopes are preferentially removed fro m the basal meltwater film and incorporated into the basal ice this process might go some way to explaining the anomalously light isotopic composition measured in base flow waters leaving some glaciers vertical isotope profiles through undeformed basal ice layers are reconstructed and show that significant isotopic excursions can occur at a scale of millimeteres while the range of isotopic compositions within such m ulti layered regelation ice is greater than that which would occur in ice produced by a single refreezing event in circumstances where the regelation system is disrupted by removal of film waters into a network of linked cavities i t is found that the remaining basal ice may be significantly enriched in heavy isotopes relative to the composition of the initial mass inputs to the system heavy isotope enrichment of this m agnitude and consideration of the thickness of the basal ice layers concerned may explain the absence of recorded basal ice samples heavy enough to h ave been formed in equilibrium with subglacial precipitates sampled at one of the sites glacier de tsanfleuron and reported in an earlier paper

evidence of cryostatic desiccation processes associated with sand intraclasts within diamictons southern ontario canada shore bluffs at mohawk bay southern ontario reveal within a complex melange of glacial sediments brecciated diamicton surrounding sand block intraclasts typically each intraclast has an aureo

a quantitative fluorescence technique for evaluating thermal maturity instrumentation and examples abstract fluorescence microscopy is useful not only for identifying most of the oil prone organic matter macerals in sedimentary rocks and coals but also for assessing their thermal maturities ranks this report introduces a violet light excitation system which induces more than one order of magnitude stronger fluorescence intensity that the commonly used uv light excitation system the red green quotient from violet light excited fluorescence q v of sporinite can be easily measured using this system several examples using coal and cuttings samples are presented to demonstrate the use of this technique for evaluating the thermal maturities of coals and sedimentary rocks from the results of our studies we conclude that 1 1 violet light excited fluorescence from sporinites can be routinely measured to assess thermal maturity 2 2 spectral quantitative fluorescence technique is useful for evaluating thermal maturity when samples are poorly polished or deficient in vitrinite 3 3 visual strew mounted kerogen slides can not be used for fluorescence measurements unless a non fluorescent mounting medium is used

ancient igneous intrusions and early expansion of the moon revealed by grail gravity gradiometry the earliest history of the moon is poorly preserved in the surface geologic record due to the high flux of impactors but aspects of that history may be preserved in subsurface structures application of gravity gradiometry to observations by the gravity recovery and interior laboratory grail mission results in the identification of a population of linear gravity anomalies with lengths of hundreds of kilometers inversion of the gravity anomalies indicates elongated positive density anomalies that are interpreted to be ancient vertical tabular intrusions or dikes formed by magmatism in combination with extension of the lithosphere crosscutting relationships support a pre nectarian to nectarian age preceding the end of the heavy bombardment of the moon the distribution orientation and dimensions of the intrusions indicate a globally isotropic extensional stress state arising from an increase in the moon s radius by 0 6 to 4 9 kilometers early in lunar history consistent with predictions of thermal models

widespread and accelerating glacier retreat on the lyngen peninsula northern norway since their little ice age maximum the recession of mountain glaciers worldwide is increasing global sea level and in many regions human activities will have to adapt to changes in surface hydrology thus it is important to provide up to date analyses of glacier change and the factors modulating their response to climate warming here we report changes in the extent of 120 glaciers on the lyngen peninsula northern norway where glacier runoff is utilised for hydropower and where glacial lake outburst floods have occurred glaciers covered at least 114 km2 in 1953 and we compare this inventory with those from 1988 2001 and a new one from 2014 and previously dated little ice age lia limits results show a steady reduction in area 0 3 a 1 between their lia maximum 1915 and 1988 consistent with increasing summer air temperatures but recession paused between 1988 and 2001 coinciding with increased winter precipitation air temperatures increased 0 5 c per decade from the 1990s and the rate of recession accelerated to 1 a 1 between 2001 and 2014 when glacier area totalled 95 7 km2 small glaciers 0 05 km2 with low maximum elevations 1400 m experienced the largest percentage losses and if warming continues several glaciers may disappear within the next two decades

thickness of proximal ejecta from the orientale basin from lunar orbiter laser altimeter lola data implications for multi ring basin formation 1 quantifying the ejecta distribution around large lunar basins is important to understanding the origin of basin rings the volume of the transient cavity the depth of sampling and the nature of the basin formation processes we have used newly obtained altimetry data of the moon from the lunar orbiter laser altimeter lola instrument to estimate the thickness of ejecta in the region surrounding the orientale impact basin the youngest and best preserved large basin on the moon our measurements yield ejecta thicknesses of 2900 m near the cordillera mountains the topographic rim of orientale decaying to 1k m in thickness at a range of 215 km these measurements imply a volume of ejecta in the region from the cordillera ring to a radial range of one basin diameter of 2 9 10 6 km 3 and permit the derivation of an ejecta thickness decay model which can be compared with estimates for the volume of excavation and the size of the transient cavity these data are consistent with the outer rook mountains as the approximate location of the transient cavity s rim crest and suggest a volume of 4 8 10 6 km 3 for the total amount

on the isotopic composition in δd and δ18o of water and ice during freezing experiments on progressive unidirectional freezing are coi1 ducted to determine rhe evol ution in 00 and 51 bo of successive water samples and ice layers ta ken during the course of freezing r es ults indicate t hal lhi s evoluti on takes pl ace in a bd bibo diagram a long a strai ght line wi th a characteri sti c slope this slope different from that due to the precip itation effec t gives a finger print of the occurrence of a freezing or of a melt ing refreez ing process in the stud ied reservoir residual water was sampled at the beginning of the experiment after 40 80 85 90 and 95 of the material had frozen when the freezing process was complete the ice core was recovered and sectioned the samples covered the freezing ranges from 0 to 10 10 to 20 20 to 50 50 to 60 60 to 70 70 to 80

pleistocene ice at the bottom of the vavilov ice cap severnaya zemlya russian arctic the vavilov ice cap was perforated in 1988 by a drilling which reached the underlying frozen sediments in contrast to the overlying glacier ice the basal ice is composed of different ice layers with a variable debris load the stable isotope composition of these layers shows values much lower than everywhere else in the core or in the vavilov ice cap this is most probably the signature of a remnant of pleistocene ice which for the first time is shown to occur in the russian arctic

3 d inversion of gravity data in spherical coordinates with application to the grail data three dimensional 3 d inversion of gravity data has been widely used to reconstruct the density distributions of ore bodies basins crust lithosphere and upper mantle for global model of 3 d density structures of planetary interior such as the earth the moon or mars it is necessary to use an inversion algorithm that operates in the spherical coordinates we develop a 3 d inversion algorithm formulated with specially designed model objective function and radial weighting function in the spherical coordinates we present regional and global synthetic examples to illustrate the capability of the algorithm the inverted results show density distribution features consistent with the true models we also apply the algorithm to a set of lunar bouguer gravity anomaly derived from the gravity recovery and interior laboratory grail gravity field and obtain a lunar 3 d density distribution high density anomalies are clearly identified underlying lunar basins a wide region of the lateral density heterogeneities that exist beneath the south pole aitken basin are found and low density anomalies are distributed beneath the feldspathic highlands terrane on the lunar far side the consistency of these results with those obtained independently from other existing methods verifies the newly developed algorithm

ice dynamics and thermal regime of taylor glacier south victoria land antarctica les donnees glaciologiques recueillies sur le taylor glacier ont servi a reconstituer les principaux traits de la dynamique et du regime thermique du glacier les etudes du bilan de masse montrent que le glacier est proche de l equilibre les conditions thermiques de la glace basale sur une grande partie de la zone d ablation ont ete calculees a partir d estimation du flux de chaleur geothermique et de mesures des temperatures de la glace pres de la surface des vitesses et de l epaisseur de la glace on a trouve que jusqu a 50 de la zone d ablation la glace basale pouvait etre fondante

periglacial features on the margins of a receding plateau ice cap lyngen north norway some features around the perimeter of the balgesvarri plateau ice cap are described sorted stone circles were found beneath a slowly retreating ice margin the basal ice in this area appears to be below the pressure melting point no absolute dating of features was possible but a relative chronology is suggested resume le retrait glaciaire et les manifestations piriglaciaires sur les marges d un glacier de calotte a lyngen norvege du nord on decrit quelques traits caracteristiques du pourtour du glacier de calotte de balgesvarri des sols polygonaux ont ete decouverts a l aval d un front glaciaire en leger retrait la glace de fond dans cette zone semble ttre en dessous du point de fusion correspondant a la pression il n a pas ete possible d etablir une datation absolue de ces manifestations periglaciaires mais on propose une chronologie relative zusammenfassung gletscherriickgang und periglaziale erscheinungen an den riindern einer plateau eiskappe lyngen nordnorwegen einige erscheinungen an der peripherie der balgesvarri plateaukappe werden beschrieben unter einem langsam zuruckgehenden eisrand wurden steinkreise gefunden das eis am untergrund dieser region durfte si ch unter dem druckschmelzpunkt befinden eine absolute datierung der erscheinungen war nicht moglich doch llisst sich eine relative zeitliche abfolge ermitteln

geology and composition of the orientale basin impact melt sheet 1 the orientale basin is one of the largest 930 km diameter and youngest 3 8 ga impact craters on the moon as the basin is only partly flooded by mare lava its floor materials expose a major portion of the basin impact melt sheet which some previous work has suggested might have undergone igneous differentiation to test this idea we remapped the geology of the orientale basin using images and topography from the lunar reconnaissance orbiter mineralogical information from the chandrayaan 1 moon mineralogy mapper and elemental concentration maps from clementine multispectral imaging and lunar prospector gamma ray data the maunder formation impact melt sheet of the basin is uniform in chemical composition equivalent to anorthositic norite in at least the upper 2 km of the deposit the deepest sampling of the basin melt sheet maximum depths of 3 5 km by the crater maunder 55 km in diameter shows a variety of lithologies but these rock types anorthosite anorthositic norite melt rocks mare basalt and gabbro are not those predicted by the differentiation model we conclude that no differentiation of the orientale basin melt sheet has occurred and that such a process is not evident from new remote sensing data for the moon or in the apollo lunar samples

the formation of glacial flutes assessment of models with evidence from lyngsdalen north norway abstract flutes are a distinctive type of glacial landform and comprise closely spaced streamlined ridges and furrows usually developed on till surfaces and aligned parallel to ice movement direction several models proposed to explain their formation involve at least in part post depositional deformation or transfer of subglacial sediments others involve primary deposition or erosion the flutes on several glacier forelands in the mountains of the southern lyngen peninsula in north norway are associated with glaciers with cold based margins to explain the formation of the flutes three main sets of variables are investigated 1 the landforms and their shapes dimensions and field relationships 2 the physical properties of the materials comprising the flutes and 3 the glacier properties and in particular the basal thermal regime and ice debris relationships at the glacier margin existing models of flute formation which involve post depositional deformation or transfer of subglacial sediments do not explain satisfactorily several aspects of the flutes found in lyngen instead a model is proposed in which the flutes are primary features formed by deformation of the basal ice layer around subglacial boulders or other obstacles

initial observations from the lunar orbiter laser altimeter lola as of june 19 2010 the lunar orbiter laser altimeter an instrument on the lunar reconnaissance orbiter has collected over 2 0 10 9 measurements of elevation that collectively represent the highest resolution global model of lunar topography yet produced these altimetric observations have been used to improve the lunar geodetic grid to 10 m radial and 100 m spatial accuracy with respect to the moon s center of mass lola has also provided the highest resolution global maps yet produced of slopes roughness and the 1064 nm reflectance of the lunar surface regional topography of the lunar polar regions allows precise characterization of present and past illumination conditions lola s initial global data sets as well as the first high resolution digital elevation models dems of polar topography are described herein

basal debris entrainment and transport in glaciers of southwestern bylot island canadian arctic abstract glaciers on southwestern bylot island in the canadian arctic flow from an alpine setting in high grade crystalline archean terrane on to coastal lowlands underlain by clastic sedimentary

weathering characteristics of arctic islands in northern norway the arctic islands of the lofoten vesteralen archipelago in northern norway have a wide distribution of weathered land surfaces commonly located above 250 m with several apparent similarities in order to investigate the characteristics of deep weathering in this region northern langoya and hadseloya were chosen for in depth analyses eight weathering profiles were excavated from various surfaces and the stratigraphies were logged in detail material was collected throughout the weathering horizons and all samples were subsequently analysed for clay mineralogy 40 000 years of subaerial conditions considering the steady surface erosion this figure should be viewed as an absolute minimum age estimate mapping of the superficial sediments and geomorphological features of the study areas has revealed several common morphological features which indicate dominance of glacial and periglacial processes in the areas lying below the lower boundary of blockfields c 250 m the weathering mantles are not a periglacial end product but rather a relict tertiary landform that were modulated by permafrost processes as well as biological processes at later stages the regolith cover constrain the vertical extension of warmbased quaternary ice sheets challenging the notion of a parabolic ice mass consuming every mountain top of lofoten and vesteralen

the density and porosity of lunar rocks 1 accurate lunar rock densities are necessary for constructing gravity models of the moon s crust and lithosphere most apollo era density measurements have errors of 2 5 or more and few include porosity measurements we report new density and porosity measurements using the bead method and helium pycnometry for 6 apollo samples and 7 lunar meteorites with typical grain density uncertainties of 10 30 kg m 3 0 3 0 9 and porosity uncertainties of 1 3 comparison between igneous grain densities and normative mineral densities show that these uncertainties are realistic and that the helium fully penetrates the pore space basalt grain densities are a strong function of composition varying over at least 3270 kg m 3 high aluminum basalt to 3460 kg m 3 high titanium basalt feldspathic highland crust has a bulk density of 2200 2600 kg m 3 and porosity of 10 20 impact basin ejecta has a bulk density of 2350 2600 kg m 3 and porosity of 20

δd δ18o relationships and the thermal history of basal ice near the margins of two glaciers in lyngen north norway les resultats des mesures combinees d et 18 o pour 2 glaciers en norvege du nord sont rapportes ainsi que leurs implications pour l histoire thermique de la glace et les variations observees dans l entrainement des debris

the geomorphological impact of loch lomond younger dryas stadial plateau icefields in the central lake district northwest england detailed geomorphological mapping has revealed evidence for the development of plateau icefields in the central fells of the english lake district during the loch lomond younger dryas stadial ca 12 9 11 5 ka the largest plateau icefield system which covered an area of approximately 55 km2 including outlet glaciers was centred on high raise to the west smaller plateau icefields developed on grey knotts brandreth and dale head covering areas of 7 km2 and 3 km2 respectively the geomorphological impact of these plateau icefields appears to have been minimal on the summits where the survival of blockfields and other frost weathered debris mostly peat covered implies the existence of at least patches of protective cold based ice ice moulded bedrock at some plateau edges however documents a transition to wet based erosive conditions prominent moraine systems were produced by outlet glaciers which descended into the surrounding valleys where their margins became sediment traps for supraglacial debris and inwash in some valleys ice marginal moraines record successive positions of outlet glaciers which actively back wasted towards their plateau source this interpretation differs from that of previous workers who assumed an alpine style of glaciation with reconstructed glaciers emanating from corries and valley heads it is likely that plateau icefields were more common at this time in upland britain than hitherto has been appreciated

rockglacier activity during the last glacial interglacial transition and holocene spring snowmelting abstract the environmental history of a talus derived rockglacier located in northern norway has been reconstructed through the last glacial interglacial transition based on two cores retrieved from an adjacent lake the methods used to quantify sedimentary properties include rock magnetism grain size analyses loss on ignition loi and bulk density which when combined has enabled an unmixing of the various sediment components and their corresponding sources rockglaciers signify mean annual air temperatures maat of 4 c or colder but little is known about their dynamical response to changing thermal regimes we document here for the first time that a permafrost regime did exist in northern norway during the lateglacial period and that it required a lowering equivalent of at least 7 c compared to present day maat the lake sediments suggest that the rockglacier existed prior to the local deglaciation of the fennoscandian ice sheet 14 800 cal yr bp and continued its expansion until the end of the younger dryas whereupon it became fossil the cool climate of the lateglacial was intersected by brief warming spells that caused a systematic release of sedimentladen meltwater from the rockglacier during the holocene the minerogenic influx to the lake was driven by spring snowmelting which are related to the magnitude of winter precipitation three phases are recognised 1 9800 6500 cal yr bp when wet winters prevailed 2 6500 4000 cal yr bp with dry winters and 3 the last 4000 cal yr bp with a return to wetter winters

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

radial gravity anomalies associated with the ejecta of the orientale basin abstract grail gravity data shows small scale gravity anomalies radiating out from the orientale basin between distances of 550 km average distance to the cordillera ring and 1000 km these radial gravity lineations are sometimes associated with secondary crater chains or catenae of which the specific details of formation and their relation to the basin ejecta remain unclear however many of the radial gravity anomalies have no clear topographic signature at all typical anomalies have an average width of about 20 km with a magnitude of 20 mgal and a length of 50 200 km here we use gravity inversions hydrocode modeling and observations to investigate the radial gravity anomalies in more detail density inversion models show that the gravity can be matched by solutions ranging from broad low amplitude anomalies with density contrasts of 20 kg m3 extending to depths of tens of kilometers to shallow high amplitude anomalies with density contrasts of about 200 400 kg m3 confined to the top 1 2 km of the crust hydrocode models of the low velocity secondary impacts of basin ejecta show that the impacting material does not disperse as occurs for hypervelocity impacts but instead remains as a thin layer within the secondary craters this remaining secondary projectile material derived from orientale ejecta can explain the linear gravity anomalies associated with secondary crater chains and catenae however this does not explain the majority of linear gravity features that are not associated with secondary crater chains therefore we conclude that the majority of radial gravity anomalies represent the structure of the ejecta deposit this density variability within the ejecta of basins likely contributes substantially to the density variability of the shallow upper crust as a whole

seasonal growth bands in pingo ice field studies of pingo ice show that alternating clear and bubble bands may grow when water freezes at the top of a subpingo water lens a study of the banding at one excellent exposure of pingo ic

blockfields old or new evidence and implications from some plateaus in northern norway evidence is presented from investigations on plateau top blockfields in still glaciated regions of north norway pits dug into these blockfields typically show profile depths 0 5 m and sometimes in excess of 1 m analysis of fines shows enrichment in the silt and clay sized fraction suggestive of prolonged chemical weathering chemical alteration of parent material is supported by xrd analysis which identifies a number of clay minerals present in blockfield samples a chemical weathering origin suggests that these plateau top blockfields are features which have considerable longevity in the landscape and have been forming since perhaps tertiary times the original weathering profiles have been destroyed by frost heaving mechanisms protection of the blockfield by cold based ice occurred during periods of glacial coverage