elevation changes of ice caps in the canadian arctic archipelago 1 precise repeat airborne laser surveys were conducted over the major ice caps in the canadian arctic archipelago in the spring of 1995 and 2000 in order to measure elevation changes in the region our measurements reveal thinning at lower elevations below 1600 m on most of the ice caps and glaciers but either very little change or thickening at higher elevations in the ice cap accumulation zones recent increases in precipitation in the area can account for the slight thickening where it was observed but not for the thinning at lower elevations for the northern ice caps on the queen elizabeth islands thinning was generally 0 5 m yr 1 which is consistent with what would be expected from the warm temperature anomalies in the region for the 5 year period between surveys and appears to be a continuation of a trend that began in the mid 1980s farther south however on the barnes and penny ice caps on baffin island this thinning was much more pronounced at over 1 m yr 1 in the lower elevations here temperature anomalies were very small and the thinning at low elevations far exceeds any associated enhanced ablation the observations on barnes and perhaps penny are consistent with the idea that the observed thinning is part of a much longer term deglaciation as has been previously suggested for barnes ice cap on the basis of the regional relationships between elevation and elevation change in our data the 1995 2000 mass balance for the archipelago is estimated to be 25 km3 yr 1 of ice which corresponds to a sea level increase of 0 064 mm yr 1 this places it among the more significant sources of eustatic sea level rise though not as substantial as the greenland ice sheet alaskan glaciers or the patagonian ice fields

changes in mass balance velocity and surface profile along a flow line on barnes ice cap 1970 1984 on a number of occasions between 1970 and 1984 measurements of mass balance surface velocity and surface elevation were made along a 10 2 km flow line extending from the divide to the margin on barnes ice cap baffin island canada the average mass balance rate on this arctic ice cap appears to be controlled principally by summer temperature years of negative mass balance dominated during the 14 year period of the study according to our measurements this should have resulted in a thinning of an average of 2 65 m along the flow line surface elevation measurements however suggest that the glacier thinned only 1 7 m during this time period the slightly compressive mean transverse strain can account for 0 20 m of the discrepancy between these two figures the rest is attributed to errors in mass balance in particular increases in density of old firn and freezing of water in crevasses could not be evaluated adequately from our measurements the thinning was not uniform near the margin the glacier thinned 5 m and near the divide 2 5 m but between 3 5 and 5 5 km from the divide there seems to have been no substantial change in thickness thus along the down glacier half of the flow line the decrease in thickness was accompanied by an increase in slope within 4 km of the margin the decrease in thickness resulted in a decrease in horizontal velocity of up to 15 despite the increase in slope higher on the glacier however the horizontal velocity increased 5 these changes are broadly consistent with those estimated from the changes in shear stress calculated using the hydrostatic approximation

the colima volcanic complex mexico part ii late quaternary cinder cones since the late pleistocene eleven cinder and lava cones have erupted on the floor of the southern colima graben ne and nw of the large active andesitic volcano colima scoria and lava samples from nine of the cones form a completely transitional basic alkalic series including basanites 9 leucite basanites 3 and minettes 15 the commonest variety of mica lamprophyre these samples represent primitive high temperature magmas with 47 6 50 3 sio2 7 4 15 3 mgo 2 5 4 4 k2o and 2 2 9 9 normative nepheline all members of this basic alkalic suite contain mg olivine fo75 94 chromite augite and late plagioclase and titanomagnetite the petrographic transition from basanite to minette is marked by the appearance of sanidine and the volatile bearing phases phlogopite apatite and analcime during late stages of crystallization as these phases increase in abundance presumably reflecting a rise in magmatic volatile content there are corresponding increases in the whole rock concentrations of 16 incompatible elements although these incompatible elements are relatively abundant even in the basanites many are highly concentrated in the minettes ba 4 200 ppm sr 3 100 ppm zr 550 ppm ce 190 ppm hf 18 ppm among the incompatible elements the degrees of enrichment in the minettes relative to the basanites decrease in the order h th ce la nd zr hf u ba sm eu pb p nb sr ti these enrichments may reflect the increasing importance of minor incompatible element rich mantle phases during partial melting the concentrations of alkali metals k na rb and cs do not correlate with these other elemental enrichments the leucite basanties have similar incompatible element contents to many minettes differing from them only in the presence of leucite rather than analcime and ti f rich groundmass phlogopite rather than hydrous phlogopite phenocrysts thus the leucite basanites represent relatively dry equivalents of minettes two of the eleven cinder cones are calc alkaline in nature and do not belong to the basanite minette group the easternmost cone is constructed of high al basalt and the northernmost of basaltic andesite the high al basalt 49 5 sio2 9 3 mgo 221 ppm ni closely approximates a parental magma to the post caldera andesitic suite of v colima 56 5 61 6 sio2 the basaltic andesite is relatively enriched in incompatible elements compared to the high al basalt v colima trend the ne normative basanite minette samples are highly enriched in incompatible elements while the contemporaneous hy qz normative calc alkaline suite encompassing the high al basalt and v colima s andesites is characterized by relatively low abundances of these elements no likely mineral assemblage can relate the alkaline and calc alkaline suites through crystal fractionation they probably represent fundamentally different melting events during the quaternary the main focus of andesitic volcanism in the southern colima graben has migrated southward with time volcan colima marks its present position 5 km south of the pleistocene volcano nevado de colima and another 15 km from the still older volcan cantaro the eruptions of basic alkalic magma probably occurred during the late stages of nevado s life and through the life of v colima they generally migrated from west to east with time towards v cantaro the most recent cone v apaxtepec is the only one east of the andesitic colima cantaro axis the oldest and the two youngest cones produced basanites while minettes dominated at cones of intermediate ages the cinder cone eruptions may have coincided with a phase of lamprophyre dike injection into plutons solidifying beneath the extinct volcanoes north of v colima the southern end of the colima graben can be viewed then as the volcanic analog of many classical post plutonic hypabyssal lamprophyre localities

loss of floating glacier tongues from the yelverton bay region ellesmere island canada a total of eight floating glacier tongues have shrunk in area by 85 from the yelverton bay region of northern ellesmere island since 1959 with unusually large losses since 2005 to better understand the causes of these losses this study undertakes the first examination of ice tongue changes in this region including an assessment of changes in surrounding marine ice i e sea ice sikussak and melange and atmospheric and oceanographic forcings from 1959 to 2017 the total ice tongue area decreased by 49 07 km 2 with the majority of this loss occurring from 2005 to 2009 34 68 km 2 the loss of ice tongues since 2005 occurred when open water replaced multi year landfast sea ice mlsi and first year sea ice in the regions adjacent to the ice tongues these changes were accompanied by an increase in mean annual mid depth i e 100 and 200 m ocean temperatures from 0 29 c from 1999 to 2005 to 0 67 c from 2006 to 2012 despite the recent return of ocean temperatures to below pre 2006 levels atmospheric summer temperatures have continued to rise 0 15 c decade 1 between 1948 and 2016 with open water continuing to occur without the sustained presence of mlsi in this region the ice tongues are unable to stabilize making it unlikely that they will re form in the current climate

the coalification pattern in the northern apennines and its palaeogeothermic and tectonic significance the rocks of the northern apennines predominantly consist of non metamorphic terrigeneous deposits flysches and molasses some of which are preorogenic some synorogenic and others postorogenic with respect to the nappe tectonics miocene as plant fragments frequently occur in these sediments a study of coal rank based on reflectance measurements on vitrinites rm mean value of the random reflectance in non polarized light contributes to the clarification of the relation between the orogenic and the palaeogeothermal development the determination of the rm values of more than 180 samples from outcrops and three deep drillings revealed some important features within the pile of liguride and tuscanide nappes the coal rank increases from the uppermost nappe to the lower nappes until lowgrade metamorphism is reached in the lower tuscanides in the single nappes the rank decreases from the tyrrhenian coast internal zone towards the po plain external zone this regional trend is disturbed only locally by young post coalification tectonics in the uppermost liguride nappe m antola unit a pre oligocene i e pre apenninic thermal event was detected postorogenic heating is connected with the magmatic activity of late miocene to pleistocene age in tuscany except for these preorogenic and postorogenic thermal events the main coalification is generally younger than the emplacement of the nappes in the nappe pile during the apenninic orogeny in the miocene but it is older than the last thrust movements and the final tensional tectonics in the internal zones of the chain for these reasons the main regional thermal event has to be considered as synorogenic or more precisely as late synorogenic

irreversible mass loss of canadian arctic archipelago glaciers 1 the canadian arctic archipelago caa contains the largest volume of glacier ice on earth outside of antarctica and greenland in the absence of significant calving caa glacier mass balance is governed by the difference between surface snow accumulation and meltwater runoff surface mass balance here we use a coupled atmosphere snow model to simulate present day and 21st century caa glacier surface mass balance through comparison with gravity recovery and climate experiment mass anomalies and in situ observations we show that the model is capable of representing present day caa glacier mass loss as well as the dynamics of the seasonal snow cover on the caa tundra next we force this model until 2100 with a moderate climate warming scenario ar5 rcp4 5 we show that enhanced meltwater runoff from caa glaciers is not sufficiently compensated by increased snowfall extrapolation of these results toward an ar5 multimodel ensemble results in sustained 21st century caa glacier mass loss in the vast majority 99 of the 7000 temperature realizations

an ice marginal δ18o record from barnes ice cap baffin island canada barnes ice cap baffin island canada is a remnant of the laurentide ice sheet that separated from it about 8500 years ago owing to recession of the ice cap during the holocene pleistocene age i

characterizing interannual variability of glacier dynamics and dynamic discharge 1999 2015 for the ice masses of ellesmere and axel heiberg islands nunavut canada landsat 7 and radarsat 1 radarsat 2 satellite images are used to produce the most comprehensive record of glacier motion in the canadian high arctic to date and to characterize spatial and temporal variability in ice flow over the past 15 years this allows us to assess whether dynamically driven glacier change can be attributed to surging or pulsing or whether other mechanisms are involved radar velocity mapping allows annual regional dynamic discharge iceberg calving to be calculated for 2000 and the period 2011 2015 yielding a mean regional discharge of 2 21 0 68 gt a 1 and velocities derived from feature tracking of optical imagery allow for annual dynamic discharge to be calculated for select glaciers from 1999 to 2010 since 2011 several of the major tidewater terminating glaciers within the region have decelerated and their dynamic discharge has decreased trinity and wykeham glaciers prince of wales icefield represent a notable departure from this pattern as they have generally accelerated over the study period the resulting increase in dynamic discharge from these glaciers entirely compensates within error limits for the decrease in discharge from the other tidewater glaciers across the study region these two glaciers accounted for 62 of total regional dynamic discharge in winter 2015 compared to 22 in 2000 demonstrating that total ice discharge from the canadian high arctic can be sensitive to variations in flow of just a few tidewater glaciers

volatile control of contrasting trace element distributions in peralkaline granitic and volcanic rocks anomalous enrichments of zr 500 ppm zn 100 ppm nb 25 ppm y 60 ppm th 20 pm u 5 ppm lree 230 ppm and hree 35ppm and high rb sr 5 characterize peralkaline granites in contrast to their peraluminous and calc alkaline equivalents within the peralkaline suite comenditic and pantelleritic volcanics exhibit two to five fold increases in the concentrations of these trace elements over comagmatic granites these cannot be explained by crystal liquid fractionation processes and require the evolution of a sodium enriched fluid corresponding trace element increases in the granites in areas of alkali metasomatism support this argument and reflect the partial confinement of this volatile phase within the high level magma chambers ree studies in particular might eventually allow an evaluation of the role of cl versus f and co3 complexing in the evolution of the volatile fluid

phosphorus and the rare earth elements in felsic magmas an assessment of the role of apatite abstract the solubility of fluorapatite in 17 silica rich melts in the system na 2 o k 2 o al 2 o 3 sio 2 with and without cao or caf 2 was determined at 1 kbar water pressure and 750 900 c apatite saturation occurs at levels of dissolved p 2 o 5 ranging between 0 04 0 02 and 0 28 0 13 wt with only 4 values outside the 0 09 0 20 wt range the results demonstrate not only that apatite is a common liquidus phase in felsic melts but also that under most circumstances it remains in the residue during episodes of partial fusion of the crust given a solubility limit of 0 14 wt dissolved p 2 o 5 the mean of the experimental values a source containing as little as 0 05 p 2 o 5 must be 35 melted before apatite is lost from the residue and no longer buffers the melt p 2 o 5 concentration at the saturation value higher abundances of p 2 o 5 in the source postpone the loss of residual apatite to still higher degrees of melting and if the source p 2 o 5 content exceeds 0 14 wt apatite must be residual for all degrees of melting increasing in abundance as melting proceeds the generally secondary influence of apatite on the rare earth element ree patterns of melt and residue is most apparent when garnet and or amphibole is minor or lacking in the residue fractional crystallization of intermediate e g andesitic magmas toward felsic compositions invariably results in saturation in apatite and some consequent depletion of ree in the melt

common trace element characteristics of crustal and mantle derived k rich magmas at mt amiata central italy rare earth and other trace element data are reported for k rich mafic inclusions and siliceous lavas from mt amiata southern tuscany italy which form an almost complete mixing series as a result of magmachamber replenishment despite a wide range of sio2 contents 48 67 wt most of the rocks are equally enriched in light ree 200 300 and heavy ree 10 15 relative to chondritic values whereas intermediate ree are slightly less abundant in the lavas compared with the inclusions eu shows negative anomalies eueu 0 49 0 70 that are most pronounced in the lavas the compatible elements cr v sc and co are found to behave like sr ba and most major elements as they show a distinct inverse correlation with sio2 while cs follows na and li and markedly increases with sio2 however k and a number of other predominantly incompatible elements viz rb zr la ce yb lu nb y hf th and u display surprisingly little or no variation and all of the rocks have unusually high concentrations of many of these elements based on arguments that mixing in the magma chamber was not accompanied by significant selective enrichment of certain elements these chemical characteristics are attributed to the end members which can be identified as a silica saturated tuscan type magma and a primitive silica undersaturated roman type magma of the high k series it is tentatively suggested that the different sources in the lower crust and upper mantle from which the end member magmas are thought to originate were metasomatized by the same fluids prior to melting

sr isotope and trace element evidence for the role of continental crust in calc alkaline volcanism on santorini and milos aegean sea greece abstract 87 sr 86 sr major and trace element data are presented for calc alkaline lavas from santorini and milos aegean sea greece 87 sr 86 sr ratios of fresh lavas from santorini range from 0 70472 to 0 70509 whereas those of fresh lavas from milos lie in the range 0 70540 0 70620 altered lavas from both islands have higher 87 sr 86 sr ratios up to 0 70573 and 0 70662 respectively the range of 87 sr 86 sr ratios of fresh lavas from santorini is only just greater that the maximum analytical uncertainty and is thus considered to reflect that of the parental magmas from which the lava series was derived by fractional crystallization at low pressures for the analysed milos lavas dacite rhyolite there is no correlation between 87 sr 86 sr and any major or trace element concentration and this together with the fact that the 87 sr 86 sr ratios are similar to those of basaltic andesites and andesites from aegina and methana in the northwestern part of the arc likewise indicates that the 87 sr 86 sr ratios are identical to those of the parental magmas from which the lava series was derived also by fractional crystallization the relatively high 87 sr 86 sr ratios of the santorini and milos parental magmas indicate that terrigenous material has played a role in their genesis this could be either via the subduction process or by assimilation of lower crustal material during ascent of mantle derived magmas the weight of the available evidence favours the latter possibility but even so there are some indications that unusual mantle source material was involved in the genesis of the magmas

six decades of glacial mass loss in the canadian arctic archipelago the canadian arctic archipelago comprises multiple small glaciers and ice caps mostly concentrated on ellesmere and baffin islands in the northern ncaa northern canadian arctic archipelago and southern parts scaa southern canadian arctic archipelago of the archipelago respectively because these glaciers are small and show complex geometries current regional climate models using 5 to 20 km horizontal resolution do not properly resolve surface mass balance patterns here we present a 58 year 1958 2015 reconstruction of daily surface mass balance of the canadian arctic archipelago statistically downscaled to 1 km from the output of the regional climate model racmo2 3 at 11 km by correcting for biases in elevation and ice albedo the downscaling method significantly improves runoff estimates over narrow outlet glaciers and isolated ice fields since the last two decades ncaa and scaa glaciers have experienced warmer conditions 1 1 c resulting in continued mass loss of 28 2 11 5 and 22 0 4 5 gt year respectively more than doubling 11 9 gt year and doubling 11 9 gt year the pre 1996 average while the interior of ncaa ice caps can still buffer most of the additional melt the lack of a perennial firn area over low lying scaa glaciers has caused uninterrupted mass loss since the 1980s in the absence of significant refreezing capacity this indicates inevitable disappearance of these highly sensitive glaciers

glacier surface temperatures in the canadian high arctic 2000 15 canada s queen elizabeth islands qei contain 14 of the world s glacier and ice cap area sparse in situ measurements indicate that interannual variability in glacier surface mass balance in this region is driven primarily by variations in summer melt and that the annual surface mass balance of four index glaciers has become increasingly negative since 2007 here we use a 16 a record of satellite derived mean summer june august land surface temperatures lst from nasa s moderate resolution imaging spectroradiometer to investigate large scale spatial and temporal variability in the duration and intensity of summer melt across glaciated surfaces in the qei from 2000 to 2015 during this period qei mean summer glacier surface temperatures increased at an average rate of 0 06 0 04 c a 1 for a total of nearly 1 c most of this increase occurred between 2005 and 2012 when mean summer near surface 2 m and upper air 700 hpa temperatures were 1 0 1 2 c higher than the 1948 2015 mean there is a strong correlation between the glacier lst and 700 hpa air temperature records r 0 8 the period 2005 12 when mean summer lsts were anomalously high was likely the warmest period in the region since at least 1948

firn cold content evolution at nine sites on the greenland ice sheet between 1998 and 2017 current sea level rise partly stems from increased surface melting and meltwater runoff from the greenland ice sheet multi year snow also known as firn covers about 80 of the ice sheet and retains part of the surface meltwater since the firn cold content integrates its physical and thermal characteristics it is a valuable tool for determining the meltwater retention potential of firn we use gap filled climatological data from nine automatic weather stations in the ice sheet accumulation area to drive a surface energy budget and firn model validated against firn density and temperature observations over the 1998 2017 period our results show a stable top 20 m firn cold content cc20 at most sites only at the lower elevation dye 2 site did cc20 decrease by 24 in 2012 before recovering to its original value by 2017 heat conduction towards the surface is the main process feeding cc20 at all nine sites while cc20 reduction occurs through low cold content fresh snow addition at the surface during snowfall and latent heat release when meltwater refreezes our simulations suggest that firn densification while reducing pore space for meltwater retention increases the firn cold content enhances near surface meltwater refreezing and potentially sets favourable conditions for ice slab formation

origin of potash rich basic lamprophyres trace element data from arizona minettes rare earth and selected trace element analyses of 15 minettes mica lamprophyres from the navajo volcanic field are presented and compared with similar data from kimberlites and selected basic rocks despite a superficial similarity it is shown that significant differences exist between the ree abundances of kimberlites and thoseof minettes and basic rocks the data suggest that the petrogenesis of minettes is more comparable to that of otherbasic magmas minette magmabeing formed by limited partial melting of garnet lherzolite under volatile rich conditions the volatile phase considered to have been derived from below the zone of partial melting is thought to possess a low co 2 co 2 h 2 o ratio in contrast to the co 2 rich vapour phases that control the formation of other basicmagmas

sensitivity of net mass balance estimates to near surface temperature lapse rates when employing the degree day method to estimate glacier melt glacier mass balance models that employ the degree day method of melt modeling are most commonly driven by surface air temperatures that have been downscaled over the area of interest using digital elevation models and assuming a constant free air lapse rate that is often taken to be the moist adiabatic lapse rate malr 6 58 ck m 1 air temperature lapse rates measured over melting glacier surface are however consistently less steep than free air values and have been shown to vary systematically with lower tropospheric temperatures in this study the implications of including a variable near surface lapse rate in a 26 year 1980 2006 degree day model simulation of the surface mass balance of devon ice cap nunavut canada are examined and compared with estimates derived from surface air temperatures downscaled using a constant near surface lapse rate equal to the measured summer mean 4 98 ck m 1 and the malr our results show that degree day models are highly sensitive to the choice of lapse rate when compared with 23 years of surface mass balance measurements from the northwest sector of the ice cap model estimates are significantly better when surface air temperatures are downscaled using a modeled daily lapse rate rather than a constant lapse equal to either the summer mean or the malr

glacier velocities and dynamic discharge from the ice masses of baffin island and bylot island nunavut canada speckle tracking of alos palsar fine beam data from 2007 2011 are used to determine the surface motion of major ice masses on baffin island and bylot island in the southern canadian arctic archipelago glacier velocities are low overall with peaks of 100 m a 1 and means of 20 60 m a 1 common along the main trunk of many outlet glaciers peak velocities on penny and bylot island ice caps tend to occur near the mid sections of their primary outlet glaciers while the fastest velocities on all other glaciers usually occur near their termini due to relatively large accumulation areas draining through narrow outlets estimates of ice thickness at the fronts of tidewater terminating glaciers are combined with the velocity measurements to determine a regional dynamic discharge rate of between 17 mt a 1 and 108 mt a 1 with a mid point estimate of 55 mt a 1 revising downward previous approximations these velocities can be used as inputs for glacier flow models and provide a baseline dataset against which

a reconciled estimate of glacier contributions to sea level rise 2003 to 2009 glaciers distinct from the greenland and antarctic ice sheets are losing large amounts of water to the world s oceans however estimates of their contribution to sea level rise disagree we provide a consensus estimate by standardizing existing and creating new mass budget estimates from satellite gravimetry and altimetry and from local glaciological records in many regions local measurements are more negative than satellite based estimates all regions lost mass during 2003 2009 with the largest losses from arctic canada alaska coastal greenland the southern andes and high mountain asia but there was little loss from glaciers in antarctica over this period the global mass budget was 259 28 gigatons per year equivalent to the combined loss from both ice sheets and accounting for 29 13 of the observed sea level rise

seven decades of uninterrupted advance of good friday glacier axel heiberg island arctic canada previous studies reported that good friday glacier had been actively surging in the 1950 60s 1990s and again in 2000 15 based on observations of terminus position change from air photos and satellite imagery we fill the gaps between previous studies and conclude that the glacier has been advancing continuously since 1959 ice surface velocities extracted from optical and synthetic aperture radar satellite images show higher flow rates than on most other marine terminating glaciers in the region this behaviour contrasts with the regional trend of glacier retreat over this period possible explanations involve a delayed response to positive mass balance conditions of the little ice age or a dynamic instability there is however insufficient evidence to attribute this behaviour to classical glacier surging as suggested in previous studies based on present day ice velocity and glacier geometry patterns in the terminus region we reconstruct the evolution of ice motion throughout the advance and suggest that what has previously been interpreted as a surge may instead have been a localised response to small scale perturbations in bedrock topography

geochronological study of the monte amiata lavas central italy k ar and fission track age measurements were performed on lava samples of monte amiata volcano central italy which is formed by a sequence of lava flows and lava domes ranging in composition from trachybasalts to high sio2 quartzlatites

dynamic thinning of glaciers on the southern antarctic peninsula growing evidence has demonstrated the importance of ice shelf buttressing on the inland grounded ice especially if it is resting on bedrock below sea level much of the southern antarctic peninsula satisfies this condition and also possesses a bed slope that deepens inland such ice sheet geometry is potentially unstable we use satellite altimetry and gravity observations to show that a major portion of the region has since 2009 destabilized ice mass loss of the marine terminating glaciers has rapidly accelerated from close to balance in the 2000s to a sustained rate of 56 8 gigatons per year constituting a major fraction of antarctica s contribution to rising sea level the widespread simultaneous nature of the acceleration in the absence of a persistent atmospheric forcing points to an oceanic driving mechanism

the geochemistry and origin of the hydrothermal water erupted at lusi indonesia abstract the spectacular lusi mud eruption started in northeast java the 29th of may 2006 despite extensive research the origin of the erupted water remains elusive and poorly constrained here we present a comprehensive study of the geochemistry of lusi waters compared with those collected from surrounding areas all collected between 2006 and 2013 including data from mud volcanoes and volcano hosted hydrothermal springs within this broad context the geochemical characteristics of the fluids expelled in the lusi region suggest that we can classify the waters in three groups 1 meteoric waters expelled in cold springs and artesian wells 2 hydrothermal waters typically mixed with meteoric waters and 3 formation water from marine sediments altered by diagenetic processes such as clay mineral dehydration samples collected from the lusi crater are cl and na dominated up to 527 mm and 471 7 mm respectively similar to seawater indicating that altered sedimentary formation waters are predominant in this system in addition they are enriched in sr up to 808 4 m and other elements commonly associated with hydrothermal systems such as li up to 877 6 m compared to 26 m in seawater some of these elements are up to ten times enriched compared to seawater values high temperature fluid mineral interactions in the subsurface appear to have facilitated the transfer of li and other mobile elements into the fluids high temperature fluid mineral interaction reactions are also supported by si concentrations significantly higher compared to other sampled mud volcanoes in the island crater samples also show the highest 18o values 5 after correction for evaporation compared to 1 at the mv localities 87sr 86sr ratios vary between of 0 7077 and 0 7083 and seem to reflect a general mixture of fluids from clay mineral dehydration carbonate recrystallization alteration of volcanic rocks and hydrothermal imprint eight years of geochemical monitoring indicate that the composition of the deep sourced lusi fluids remain fairly constant through time thus our findings show that the lusi crater waters represent a regional geochemical anomaly and we suggest that a combination of high temperatures in the source region and fluid rock interactions with silicates and possibly carbonate rich lithologies can explain the data this is consistent with a model where the emitted gases migrate from a deep seated 4 km source region likely associated with the presence of hot igneous intrusions and or high t reactions related to the presence of neighbouring active volcanoes

changes in accumulation area firn stratigraphy and meltwater flow during a period of climate warming devon ice cap nunavut canada 1 to document climate driven changes in firn stratigraphy and their implications for meltwater flow patterns within firn on the devon ice cap nunavut during the 21st century summer warming 500 mhz ground penetrating radar gpr surveys were conducted along a 40 km transect in each spring from 2007 to 2012 these linear gpr surveys were supplemented by four 190 m by 100 m gpr grid surveys and 36 firn cores increased meltwater percolation and infiltration ice formation associated with high surface melt rates since 2005 modified the firn stratigraphy substantially over a horizontal distance of nearly 30 km the most dramatic change involved the growth of a thick ice layer within the firn body this layer grew primarily by upward accretion over an initial widespread ice layer formed during summer 2005 it thickened by between 0 5 and 4 5 m over the study period and filled much of the pore volume in the upper part of the firn reducing vertical percolation of meltwater into deeper sections of the firn and thus the water storage potential of much of the firn reservoir heterogeneous percolation of surface meltwater promoted by rolling topography played an important role in meltwater infiltration and drainage encouraging lateral flow at the tops of small hills and ponding and refreezing of meltwater beneath surface depressions

meltwater percolation impermeable layer formation and runoff buffering on devon ice cap canada the retention of meltwater in the accumulation area of the greenland ice sheet and other arctic ice masses buffers their contribution to sea level change however sustained warming also results in impermeable ice layers or ice slabs that seal the underlying pore space here we use a 1 d physically based high resolution model to simulate the surface mass balance smb percolation refreezing ice layer formation and runoff from across the high elevation area of devon ice cap canada from 2001 to 2016 we vary the thickness of the impermeable ice layer at which underlying firn becomes inaccessible to meltwater thick near surface ice layers are established by an initial deep percolation the formation of decimetre ice layers and the infilling of interleaving pore space the cumulative smb increases by 48 by varying impermeable layer thickness between 0 01 and 5 m within this range we identify narrower range 0 25 1 m that can simulate both the temporal variability in smb and the observed near surface density structure across this range cumulative smb variation is limited to 6 and 45 49 of mass retention takes place within the annually replenished snowpack our results indicate cooler summers after intense mid 2000s warming have led to a partial replenishment of pore space

polyphase metamorphic sedimentary xenoliths from mt amiata volcanics central italy evidence for a partially disrupted contact aureole metasedimentary inclusions in the crustal anatectic rhyodacites of mt amiata volcanic complex can be subdivided into a silica poor group rich in aluminous minerals and a small silica rich group containing abundant quartz textural observations supported by mineral chemistry provide evidence for three metamorphic events the regional metamorphic m0 is often associated with deformation and two subsequent progressive thermometamorphic events m1 and m2 are caused by the magmatic heat mineral assemblages of m1 are indicative for the pyroxene hornfels facies and assemblages of m2 in combination with evidence for partial melting and sanidinization suggest sanidinite facies conditions the inclusions are interpreted mainly as xenolithic fragments of a contact aureole which were remetamorphosed after incorporation by the magma the aureole formed in pre mesozoic formations during accumulation of the melt in a magmachamber constraints on pressure conditions for m1 indicate the possibility of a fairly large depth of the heat source giving rise to mt amiata geothermal field

the geochemistry and petrogenesis of the lavas of the vulsinian district roman province central italy the vulsinian lavas are dominated by a suite of undersaturated leucite bearing basic to intermediate compositions the remaining lavas are mainly oversaturated and have shoshonitic affinities one hundred and thirty five samples have been analysed for major elements and most for 20 trace elements twenty seven lavas have been analysed for ree they are all perpotassic for the undersaturated lavas k2o na2o 2 8 and have very high lil element concentrations e g rb 400 800 ppm th 25 150 ppm ree reecho c 200 lree hree cho c 20 even in the most basic rocks

the randolph glacier inventory a globally complete inventory of glaciers the randolph glacier inventory rgi is a globally complete collection of digital outlines of glaciers excluding the ice sheets developed to meet the needs of the fifth assessment of the intergovernmental panel on climate change for estimates of past and future mass balance the rgi was created with limited resources in a short period priority was given to completeness of coverage but a limited uniform set of attributes is attached to each of the 198 000 glaciers in its latest version 3 2 satellite imagery from 1999 2010 provided most of the outlines their total extent is estimated as 726 800 34 000 km 2 the uncertainty about 5 is derived from careful single glacier and basin scale uncertainty estimates and comparisons with inventories that were not sources for the rgi the main contributors to uncertainty are probably misinterpretation of seasonal snow cover and debris cover these errors appear not to be normally distributed and quantifying them reliably is an unsolved problem combined with digital elevation models the rgi glacier outlines yield hypsometries that can be com bined with atmospheric data or model outputs for analysis of the impacts of climatic change on glaciers the rgi has already proved its value in the generation of significantly improved aggregate estimates of glacier mass changes and total volume and thus actual and potential contributions to sea level rise

rare earth element distributions among minerals in a granodiorite and their petrogenetic implications a study of the distribution of lanthanide rare earths in a granodiorite from the eastern peninsular ranges batholith southern california reveals that a large fraction of the ree in this rock resides in the accessory phases sphene and allanite the minerals plagioclase alkali feldspar biotite epidote and apatite each contribute approximately 1 or less of each ree to the whole rock with the exception of eu for which plagioclase contributes 7 sphene and allanite together contain 80 to 95 of each ree each of these phases is zoned in ree concentration with substantial decreases from core to margin textural observations argue for relatively early saturation and precipitation of sphene and allanite in the magma ree zoning trends in sphene and allanite and unexpectedly low ree concentrations in largely later crystallizing minerals such as feldspar indicate that the precipitation of sphene and allanite significantly reduced ree concentrations in residual melts these results illustrate the potential that sphene and allanite have for controlling the behavior of ree in granitic magmas available information collectively suggest that the sampled granodiorite existed as a complete melt that the ree contained in the assemblage of phases were derived by direct crystallization from the melt and that the melt behaved essentially as a closed system once crystallization of the phases now present began close correspondences between the major and trace element chemistries of the granodiorite and phenocryst poor lavas from similar tectonic settings support these conclusions the ree pattern of the granodiorite melt appears to have originated at depth and is characteristic of its source regions and derivation mechanism the high liquidus temperature of a granodiorite melt 1000 c indicates the importance of mantle derived components within the sources of batholithic magmas in the peninsular ranges

sharply increased mass loss from glaciers and ice caps in the canadian arctic archipelago the canadian arctic archipelago contains one third of the global volume of land ice outside the ice sheets but its contribution to sea level change is largely unknown gardner et al use three independent techniques to reveal that mass loss from the archipelago was 92 12 gigatonnes per year in 2007 09 about three times greater than in 2004 06 and coincident with warmer summer temperatures the record is too short to allow a firm conclusion on longer term trends but it is clear that the canadian arctic archipelago is a significant contributor to sea level rise mountain glaciers and ice caps are contributing significantly to present rates of sea level rise and will continue to do so over the next century and beyond1 2 3 4 5 the canadian arctic archipelago located off the northwestern shore of greenland contains one third of the global volume of land ice outside the ice sheets6 but its contribution to sea level change remains largely unknown here we show that the canadian arctic archipelago has recently lost 61 7 gigatonnes per year gt yr 1 of ice contributing 0 17 0 02 mm yr 1 to sea level rise our estimates are of regional mass changes for the ice caps and glaciers of the canadian arctic archipelago referring to the years 2004 to 2009 and are based on three independent approaches surface mass budget modelling plus an estimate of ice discharge smb d repeat satellite laser altimetry icesat and repeat satellite gravimetry grace all three approaches show consistent and large mass loss estimates between the periods 2004 2006 and 2007 2009 the rate of mass loss sharply increased from 31 8 gt yr 1 to 92 12 gt yr 1 in direct response to warmer summer temperatures to which rates of ice loss are highly sensitive 64 14 gt yr 1 per 1 k increase the duration of the study is too short to establish a long term trend but for 2007 2009 the increase in the rate of mass loss makes the canadian arctic archipelago the single largest contributor to eustatic sea level rise outside greenland and antarctica

summer melt rates on penny ice cap baffin island past and recent trends and implications for regional climate 1 at latitude 67 n penny ice cap on baffin island is the southernmost large ice cap in the canadian arctic yet its past and recent evolution is poorly documented here we present a synthesis of climatological observations mass balance measurements and proxy climate data from cores drilled on the ice cap over the past six decades 1953 to 2011 we find that starting in the 1980s penny ice cap entered a phase of enhanced melt rates related to rising summer and winter air temperatures across the eastern arctic presently 70 to 100 volume of the annual accumulation at the ice cap summit is in the form of refrozen meltwater recent surface melt rates are found to be comparable to those last experienced more than 3000 years ago enhanced surface melt water percolation and refreezing have led to a downward transfer of latent heat that raised the subsurface firn temperature by 10 c at 10 m depth since the mid 1990s this process may accelerate further mass loss of the ice cap by pre conditioning the firn for the ensuing melt season recent warming in the baffin region has been larger in winter but more regular in summer and observations on penny ice cap suggest that it was relatively uniform over the 2000 m altitude range of the ice cap our findings are consistent with trends in glacier mass loss in the canadian high arctic and regional sea ice cover reduction reinforcing the view that the arctic appears to be reverting back to a thermal state not seen in millennia

recent elevation changes of svalbard glaciers derived from icesat laser altimetry abstract we have tested three methods for estimating 2003 2008 elevation changes of svalbard glaciers from multi temporal icesat laser altimetry a linear interpolation of crossover points between ascending and descending tracks b projection of near repeat tracks onto common locations using digital elevation models dems and c least squares fitting of rigid planes to segments of repeat track data assuming a constant elevation change rate the two repeat track methods yield similar results and compare well to the more accurate but sparsely sampled crossover points most glacier regions in svalbard have experienced low elevation thinning combined with high elevation balance or thickening during 2003 2008 the geodetic mass balance excluding calving front retreat or advance of svalbard s 34 600 km2 glaciers is estimated to be 4 3 1 4 gt y 1 corresponding to an area averaged water equivalent w e balance of 0 12 0 04 m w e y 1 the largest ice losses have occurred in the west and south while northeastern spitsbergen and the austfonna ice cap have gained mass winter and summer elevation changes derived from the same methods indicate that the spatial gradient in mass balance is mainly due to a larger summer season thinning in the west and the south than in the northeast our findings are consistent with in situ mass balance measurements from the same period confirming that repeat track satellite altimetry can be a valuable tool for monitoring short term elevation changes of arctic glaciers

geochemical characteristics of the south tuscany italy volcanic province constraints on lava petrogenesis abstract three suites of volcanic rocks from radicofani mts cimini and mt amiata south tuscany italy were analyzed for major and trace element contents and sr isotopic composition all samples are silica saturated hypersthene normative and some are peraluminous samples from radicofani and the less evolved mts cimini samples have high mg numbers 74 5 66 3 consistent with the fosteritic rich nature of their olivine phenocrysts and high bulk rock abundances of ferromagnesian trace elements all samples are highly enriched in light ree 150 315 chondrites compared to heavy ree 9 15 chondrites and have negative eu anomalies eu eu 0 92 0 44 87 sr 86 sr ratios are high and variable radicofani 0 7137 0 7150 mts cimini 0 7128 0 7138 mt amiata 0 7119 0 7131 a distinctive feature of the radicofani samples is that with decreasing age the rocks increase in k2o content but decrease in la ce these south tuscany rocks have geochemical characteristics of the calc alkaline and alkaline series namely in addition to the high k rb cs ba and lree contents they have high ratios of incompatible elements relative to the high field strength ions such as ti zr hf nb and hree when compared to an estimated primitive mantle composition in general the geochemical characteristics of south tuscany volcanics are consistent with mixing between crustal derived material and mantle derived magma the mantle derived component was unusually rich in radiogenic sr and incompatible elements and had geochemical features similar to basic lavas of the high k series in the roman province

the projected demise of barnes ice cap evidence of an unusually warm 21st century arctic as a remnant of the laurentide ice sheet barnes ice cap owes its existence and present form in part to the climate of the last glacial period the ice cap has been sustained in the present interglacial climate by its own topography through the mass balance elevation feedback a coupled mass balance and ice flow model forced by coupled model intercomparison project phase 5 climate model output projects that the current ice cap will likely disappear in the next 300 years for greenhouse gas representative concentration pathways of 2 6 to 8 5 wm 2 the projected ice cap survival times range from 150 to 530 years measured concentrations of cosmogenic radionuclides 10be 26al and 14c at sites exposed near the ice cap margin suggest the pending disappearance of barnes ice cap is very unusual in the last million years the data and models together point to an exceptionally warm 21st century arctic climate

complex interaction of aluminous metasedimentary xenoliths and siliceous magma an example from mt amiata central italy aluminous silica deficient metasedimentary xenoliths in siliceous lavas of mt amiata have preserved composite zoning patterns indicative for complex processes of magma rock interaction petrographic observations and small scale mineralogical and chemical differences between up to five distinct zones including the core and envelope of lava provide evidence that quartz poor muscovite biotite schists are considered to be the most likely parent rocks and it is believed that release of volatiles from decomposing micas played a significant role in the high temperature metamorphic evolution of the xenoliths and their interaction with the magma the conditions favourable for assimilation were enhanced by injection of mafic magma into the magma chamber although this concurrent operation of magma mixing precludes a quantitative estimate of contamination from the wall rocks which was probably of minor importance the present example indicates that dry acid magma may potentially become more mafic by interaction with partially melted hydrous rocks

revised estimates of recent mass loss rates for penny ice cap baffin island based on 2005 2014 elevation changes modified for firn densification repeat airborne or satellite measurements of surface elevation over ice caps are often used tocalculate glacier wide surface mass changes over time however these measurements typically do notacco

iceberg calving rates from northern ellesmere island ice caps canadian arctic 1999 2003 optical satellite imagery was used to estimate glacier surface velocities and iceberg calving rates from agassiz and western grant ice caps nunavut canada between 1999 and 2003 the largest mean annual surface velocities ranged from 400 to 700 m a 1 but velocities in the 100 200 m a 1 range were common summer velocities were up to an order of magnitude larger than annually averaged velocities the highest velocity 1530 m a 1 was measured on the floating tongue of lake tuborg glacier between 19 july and 19 august 2001 calving rates from individual glaciers varied by up to a factor of two between successive years summer calving rates were 2 8 times larger than annual average rates the average ratio of the calving flux due to terminus volume change to that due to ice flow through the glacier terminus was 0 81 for the annual rates and 1 71 for summer rates the estimated mean annual calving rate from agassiz ice cap in the period 1999 2002 was 0 67 0 15 km 3 a 1 o f which 54 emanated from eugenie glacier alone this total rate is similar to a previously estimated calving rate from devon ice cap

evidence for mantle metasomatism an oxygen and strontium isotope study of the vulsinian district central italy this paper presents new o and sr isotope data for lavas from the northern part of the roman perpotassic province the samples comprise the tephritic leucititic to leucite phonolitic lavas and the saturated lavas from the vulsinian district the olivine leucite melilitite of san venanzo and the kalsilite diopside melilitite of cupaello previous oxygen isotope work on the lavas of the vulsinian district suggested crustal contamination of normal mantle derived magmas the new data cover the ranges previously found o and sr isotope ratios of evolved lavas of the undersaturated suite indicate assimilation in variable amounts of up to ca 10 of continental crustal material the saturated lavas probably assimilated large amounts up to ca 50 of crust lavas chemically identified as corresponding to little modified mantle derived liquids are high in both87sr 86sr and 18o 0 7103 0 7107 7 8 to 9 4 vulsini 0 7104 12 3 san venanzo and 0 7112 14 4 cupaello these high values are interpreted to have been inherited from a metasomatized parental mantle hydrous fluids enriched in large ion lithophile elements and high in 18o and87sr 86sr are thought to have mixed with mantle of normal 18o and87sr 86sr the fluids probably origi dehydration of continent derived sediments which were subducted beneath a mantle wedge in the continent continent collision of the corsica sardinia block and the adriatic italian plate this hypothesis is supported by pb and nd isotopic evidence and is probably valid for the entire roman province