characterization of granitoid and gneissic weathering profiles of the mucone river basin calabria southern italy the paper deals with the development of a multidisciplinary research on weathering profiles of granitoid and gneissic rocks related to tectonic and landscape evolution of the western sila grande massif calabria southern italy field scale observations and petrographical and mineralogical features are used to characterize in detail the weathering processes the weathering profiles of the granitoid cut slopes are generally simple showing a progressive weathering increase toward the top of the slopes whereas the weathering profiles of the gneissic cut slopes are generally complex with irregularities in the spatial distribution of weathered horizons the microfabric and petrographic analyses show that gneissic samples classes v vi of weathering grade are characterized by higher percentage of altered minerals and microfracture and void rather than granitoid samples classes v vi of weathering grade the main mineralogical changes concern the partial transformation of biotite and the partial destruction of feldspars mainly plagioclases associated with the neoformation of secondary minerals clay minerals and fe oxides and with a substitution of the original rock fabric neoformed clay minerals and ferruginous products replaced feldspars and biotite during the most advanced weathering stage referred as physical changes coupled with chemical variations the final results of weathering process are a soil like material characterized by sand gravel grain size fraction for the granitoid rocks and by both silt clay and sand silt grain size fraction for the gneissic rocks this generally produces a greater value of the sgi sand generation index for granitoids and explains the great productivity in sandy deposits of this lithology

weathering and morphogenesis in a mediterranean climate calabria italy abstract deeply weathered plutonic rocks occur widely in the sila massif calabria southern italy three representative weathering profiles developed on the hilltops indicate that sand represents more than 50 by weight throughout most of the weathering profile and silt and clay size fractions are also well represented filling the interstices among corestones both sand and finer fractions of grus and soil horizons are thought to be derived from a combination of granular disintegration and chemical decomposition developed on relatively flat terrains of the sila massif these slopes are now experiencing transport limited morphodynamics under a montane modified mediterranean climate the depth of the weathered layers that have suffered little erosional truncation typically exceed 15 m and may reach 50 60 m or more major isolated or grouped exfoliation boulders are the most common minor landform feature developed on the sila massif granite boulders have developed as a result of spheroidal weathering and by removal of the sandy textured granite the schmidt hammer sh test on boulders and corestones suggests three distinctive degree of weathering from moderately to completely weathered rock and that biotite content is the major controlling factor of the granite mechanical behaviour understanding of the dynamics of this weathering system is crucial to the interpretation of the complex suite of variables that control landscape evolution of granitoid terrains

tectonic constraints on a deep seated rock slide in weathered crystalline rocks abstract deep seated rock slides dsrss recognised as one of the most important mass wasting processes worldwide involve large areas and cause several consequences in terms of environmental and economic damage they result from a complex of controlling features and processes dsrss are common in calabria southern italy where the complex geo structural setting plays a key role in controlling the geometry of the failure surface and its development this paper describes an integrated multi disciplinary approach to investigate a dsrs in palaeozoic high grade metamorphic rocks of the sila massif it focuses on the definition of the internal structure and the predisposing factors of the serra di buda landslide near the town of acri which is a paradigm for numerous landslides in this area an integrated interdisciplinary study based on geological structural and geomorphological investigations including field observations of weathering grade of rocks minero petrographic characterisations geotechnical investigations and in particular fifteen years of displacement monitoring is presented stereoscopic analysis of aerial photographs and field observations indicate that the serra di buda landslide consists of two distinct compounded bodies i an older and dormant body 7 ha and ii a more recent and active body 13 ha that overlies the previous one the active landslide shows movement linked to a deep seated translational rock slide block slide the velocity scale ranges from slow 1 6 m year during paroxysmal stages to extremely slow

mixing processes in modern estuarine sediments from the gulf of khambhat western india abstract sandy and muddy detritus from two distinctive end member provenance terrains basaltic and granitic are transported to the estuaries of the gulf of khambhat by fluvial discharge and opposing tidal currents making this embayment ideal for investigating the effects of mineralogical and geochemical mixing on sediment composition in estuarine depositional systems rivers flowing predominantly from the north over precambrian metasediments and granites supply a felsic plutoniclastic sand to the gulf whilst a mafic volcaniclastic sand sourced by deccan basalts is transported by rivers draining the western ghats and from the local coastal erosion in the southern part of the gulf sediments from the tapti estuary are rich in basaltic rock fragments 50 and are characterised by a distinctly basaltic source composition la sc 0 25 0 86 th sc 0 12 0 40 cr th 13 121 eu eu 0 93 1 68 and lree hree 2 96 6 57 by contrast the sediments of the sabarmati inner estuary are rich in quartz grains 80 as evident from the major and trace element compositions la sc 1 38 6 63 th sc 0 58 2 98 cr th 0 58 19 39 eu eu 0 46 0 86 and lree hree 2 90 11 40 the detrital compositions of the remaining major estuaries the narmada dhadhar and mahi scatter across a broad range in a qfr diagram and contain varying amounts of quartz feldspar and rock fragments in the narmada estuary the mixed signature characterised by ree values including eu eu 0 42 2 28 and lree hree 4 37 14 80 is caused by the presence of diverse rock types that crop out in the source area in the mahi estuary which largely flows across felsic source terrains the compositional signature is controlled by mixing of felsic detritus from riverine input with mafic sediments from seaward side in the estuary the two end member detrital compositions plutoniclastic and volcaniclastic are mixed in the macro tidal estuaries mixing of sediment takes place where fluvial currents and tidal flows interact and the proportion of mixing varies systematically from outer to central to inner estuary a high degree of mixing of felsic sediments with deccan basalt derived sediments takes place in the outer estuary resulting in felsic mafic ratios of 40 60 sediments in the central estuaries 65 35 and in the fluvial dominated inner estuaries 90 10 are characterised by moderate to minor degrees of mixing the mixing in estuaries is systematic and is reflected in both the mineralogy and geochemistry of the sediments provenances of ancient estuarine successions should therefore be interpreted with great care incorporating awareness of the mixing processes which influence sediment compositions to different degrees in estuaries especially those characterised by strong tidal currents

ocean forcing of the greenland ice sheet calving fronts and patterns of retreat identified by automatic satellite monitoring of eastern outlet glaciers 1 we have developed an automatic method to identify changes in the position of calving glacier margins using daily modis imagery application of the method to 32 ocean terminating glaciers in east greenland produced 26 802 margin positions for a 10 year long period 2000 2009 we report these high resolution data and show that the glaciers exhibit seasonal cycles with magnitudes of advance and retreat proportional to glacier width despite similar seasonality there is a distinct difference between the interannual trends of calving front positions north and south of 69 n all glaciers above this latitude showed very limited or no change when seasonality was excluded while glaciers south of 69 n retreated significantly between 2001 and 2005 2 3 km on average approximately 26 of the retreat of southern glaciers was regained by readvance from 2005 to 2009 to explain the latitudinal boundary of glacier dynamics we review basic climatic factors including summer and winter atmospheric forcing sea ice conditions and ocean temperature we conclude that the southern retreats were strongly influenced by warm oceanic conditions associated with increased transport of subtropical waters to the irminger sea and to fjords and coastal regions south of 69 n northern glaciers remained stable despite significant increase in runoff in this region because fjords at latitudes higher than 69 n are less exposed to subtropical waters the southern retreats illustrate sensitive behavior of calving glaciers and we hypothesize that the calving fronts retreated because they were exposed to rapid ice front melting

multi decadal retreat of greenland s marine terminating glaciers many marine terminating glaciers draining the greenland ice sheet have retreated over the past decade yet the extent and magnitude of retreat relative to past variability is unknown we measure changes in front positions of 210 marine terminating glaciers using landsat imagery spanning nearly four decades and compare decadal scale rates of change with earlier observations we find that 90 of the observed glaciers retreated between 2000 and 2010 approaching 100 in the northwest with rapid retreat observed in all sectors of the ice sheet the current retreat is accelerating and likely began between 1992 and 2000 coincident with the onset of warming following glacier stability and minor advance during a mid century cooling period while it is clear an extensive retreat occurred in the early 20th century a period of increasing air temperatures a comparison of our results with historical observations provides evidence that the current retreat is more widespread the onset of rapid retreat with warming relative to the slow and lagged advance with cooling suggests an asymmetry in the response of marine fronts to external forcing

a multidisciplinary approach to investigate weathering processes affecting gneissic rocks calabria southern italy abstract the paper focuses on the weathering processes affecting gneissic rocks of the western sila grande massif calabria italy through the development of an interdisciplinary research based on field studies and investigations minero petrographical analyses and geochemical modeling both physical and chemical weathering affect gneissic rocks of the study area where the combination of tectonic and past climatic conditions played an important key role in the development of complex and deep weathering profiles field surveys and cut slope analyses highlight articulated and complex geometric relationships between various classes of weathering i e out of sequence weathering horizons giving rise to a partial or even complete inversion of the normal weathering profile the weathering profile has turned out particularly intense as classes iv v and vi are widespread among the class vi the colluvial soils are prominent in comparison whit the residual soils borehole logs that confirm the intensity and complexity of weathering profiles in deep allow to estimate the presence of weathered rocks to be at least 70 m in thicknesses the main mineralogical modifications linked to weathering processes concern the partial transformation of biotite and the partial destruction of feldspars mainly plagioclases associated with the neoformation of secondary mineralogical phases clay minerals and fe oxides neoformed clay minerals such as sericite illite and mixed layer phases and ferruginous products replaced feldspars and biotite during the most advanced weathering stage results of xrd analyses and geochemical modelling provide a good indication on the secondary mineral assemblage due to the increase of the weathering intensity form class iii to class vi that reflects the different contributions of chemical elements provided by dissolution of silicate minerals into the surrounding groundwater system the chemical composition of the studied rock samples and the oxides variations suggest a removal of some alkali na and k and alkaline earth ca and mg into solution as a consequence of weathering reactions the chemical analysis and the weathering indices cia pia ciw and ciw show a marked alteration process with ferromagnesian minerals and feldspars probably dissolved and leached into the surrounding groundwater system the co2 controlled dissolution of plagioclase appears to be the most important reaction during chemical weathering the progressive dissolution results then dominated by biotite followed by a minor amounts k feldspar chlorite and garnet whereas the sillimanite shows a neglectable amounts the secondary solid phases observed during the geochemical modeling illite followed by vermiculite ferrihydrite and saponite are similar to those found in this natural system the proposed approach could be used to characterize weathered crystalline rocks and related weathering profiles in similar geological setting and the obtained results represent a key point for the evaluation of the control exerted by weathering on landscape evolution under current environmental settings in terms of sediment generation soil erosion rates and mass movements and for the mechanical characterization of weathering profiles for engineering geological purposes

minero petrographical features of weathering profiles in calabria southern italy abstract the paper reports interdisciplinary research of weathering profile stages on gneiss with regard to tectonic and landscape evolutions of the western sila grande massif southern italy the outcropping rocks consist of medium to coarse grained biotite garnet and sillimanite gneiss bgs g and medium to coarse grained biotite muscovite migmatitic gneiss m g the bgs g rocks are fractured and weathered with either massive or foliated texture whereas the m g rocks are intensely weathered and fractured with a massive texture and frequent pegmatite veins petrographical and mineralogical variations show that both gneissic rocks bgs g and m g samples underwent weathering processes characterized by a progressive chemical attack on the labile minerals with generation of neoformed minerals and substitution of the original rock fabric the weathering processes produced phyllosilicates and fe oxides neoformed clay minerals and ferruginous products replaced feldspars and biotite during the most advanced weathering stage microfractures and morphological variations occur on the original rock and thereby affect the surrounding landscape processes the weathering profile mineralogy and rock textures viewed in the context of landscape evolution provide useful insights into the widespread slope movement phenomena in the sila grande massif gneiss

the effects of source lithology transport deposition and sampling scale on the composition of southern california sand the transverse ranges of southern california represent an uplifted and variably dissected mesozoic magmatic arc and mesozoic to holocene sedimentary and volcanic strata deposited in convergent and transform tectonic settings modern sand within part of the western transverse ranges represents first order sampling scale of the santa monica and the san gabriel mountains second order sampling scale of the santa clara river draining both mountain ranges and third order sampling scale of the beach system between the mouth of the santa clara river and the eastern santa monica mountains and turbidite sand of the hueneme mugu submarine fan source lithology includes plutonic and metamorphic rocks of the san gabriel mountains and sedimentary and volcanic rocks of the santa monica mountains first order sands have large compositional variability sand from local coastal drainage of the santa monica mountains ranges from basaltic feldspatholithic to quartzofeldspathic sand of the san gabriel mountains local drainages has three distinct petrofacies ranging from metamorphiclastic feldspatholithic to mixed metamorphi plutoniclastic and plutoniclastic quartzofeldspathic second order sand is represented by the main channel of the santa clara river the sand has an abrupt downstream compositional change from feldspathic to quartzofeldspathic third order sand beaches and deep sea turbidite samples of the santa monica basin is quartzofeldspathic beach sand is more quartz rich than is santa clara river sand whereas turbidite sand is more feldspar rich than is beach sand deep sea sand has intermediate composition with respect to second order samples of the santa clara river and third order samples of the beach system suggesting that 1 the santa clara river is the main source of sediments to the marine environment and 2 local entry points from canyons located near local drainages may generate turbidity currents during exceptional flood conditions petrologic data of modern sand of the study area are highly variable at first and second order scale whereas third order sand is homogenized the homogenized composition of deep marine sand is similar to the composition of most ancient sandstone derived primarily from the mesozoic dissected magmatic arc of southern california this study of the western transverse ranges illustrates the effects of source lithology transport depositional environment and sampling scale on sand composition of a complex system which provides insights regarding actualistic petrofacies models

turbidite deposition from multiple sources quaternary paola basin eastern tyrrhenian sea abstract the western margin of the calabrian arc is underlain by a thick as much as 5 km post miocene sedimentary succession the uppermost part of this margin sequence is referred to as the paola basin system quaternary in age and partially fills a present day physiographic slope basin seismic and high resolution reflection profiles reveal that a prominent unconformity marks the base of the paola basin system pbs the unconformity connects upslope to an area of recurrent shelf edge instability and is overlain by large mass failure deposits over much of the basin area basin wide sedimentary drape deposits form stratigraphic markers that subdivide the paola basin system into three stages each with unique patterns of slope erosion including mass wasting and lower slope to basin floo turbidite deposition three major sediment pathways elongated perpendicular to the margin developed between the unconformity and the first basin wide drape upsection sediment input for turbidite sedimentation in paola basin has involved many commonly ephemeral point sources most of the turbidite deposits do not form complete submarine fan sequences but consist of only a few turbidite elements changes in the size and type of turbidite elements through time suggest a decrease in the size and or duration of individual sediment sources in the latest pleistocene the paola basin system is an example of a complex fill of a tectonically controlled basin where the effects of cyclic eustatic changes in sea level modify the effects of longer term changes in sedimentation driven by tectonic ctivity in the source region and structural deformation in the depositional area

acceleration of the contribution of the greenland and antarctic ice sheets to sea level rise 1 ice sheet mass balance estimates have improved substantially in recent years using a variety of techniques over different time periods and at various levels of spatial detail considerable disparity remains between these estimates due to the inherent uncertainties of each method the lack of detailed comparison between independent estimates and the effect of temporal modulations in ice sheet surface mass balance here we present a consistent record of mass balance for the greenland and antarctic ice sheets over the past two decades validated by the comparison of two independent techniques over the last 8 years one differencing perimeter loss from net accumulation and one using a dense time series of time variable gravity we find excellent agreement between the two techniques for absolute mass loss and acceleration of mass loss in 2006 the greenland and antarctic ice sheets experienced a combined mass loss of 475 158 gt yr equivalent to 1 3 0 4 mm yr sea level rise notably the acceleration in ice sheet loss over the last 18 years was 21 9 1 gt yr2 for greenland and 14 5 2 gt yr2 for antarctica for a combined total of 36 3 2 gt yr2 this acceleration is 3 times larger than for mountain glaciers and ice caps 12 6 gt yr2 if this trend continues ice sheets will be the dominant contributor to sea level rise in the 21st century

identification of rain and low backscatter regions in x band marine radar images an unsupervised approach in this article an unsupervised clustering based method for identifying rain contaminated and low backscatter regions in x band marine radar images is presented rain blurs the wave signatures of radar images and low backscatter images caused by calibration errors or too low wind speed contain little or no wave signatures in both cases ocean surface parameter measurement using x band marine radar will be negatively affected four types of features can be extracted based on the distinct difference in texture and pixel intensity distribution between rain free rain contaminated and low backscatter regions features extracted from each pixel are combined into a feature vector and mapped onto a 10 times 10 neuron self organizing map som then the hierarchical agglomerative clustering algorithm is introduced which clustered those neurons into three types i e rain free rain contaminated and low backscatter the method is validated using the shipborne marine radar data collected on the east coast of canada the good agreement between the pixel based clustering results and manually segmented reference images indicates that both rain contaminated and low backscatter regions can be identified effectively using the proposed method

sand composition in an iberian passive margin fluvial course the tajo river the tajo river the 10th largest river in europe drains part of the western passive margin of europe that includes multiple tectonic elements of the iberian plate modern fluvial sand composition in the tajo river drainage basin reflects the nature of the source region which lies in the central part of the iberian peninsula four fluvial petrographic provinces a b c and d can be established in the tajo drainage basin corresponding well with the four principal structural units drained 1 the iberian range 2 the hesperian massif 3 the tertiary tajo basin and 4 the neogene santarem lisboa basin province a corresponds to the tajo river head and is characterized by quartzolithic sedimenticlastic sands qm67f4lt29 and rs79rg3rm18 these sands have been derived from diverse mesozoic siliciclastics and carbonates of the iberian range province b appears in the upper reaches of the tajo river course and is quartzofeldspathic qm57f34lt9 with diverse rock fragments rs34rg23rm43 sources are hercynian granitoids and metasediments and neogene clastics and minor carbonates of the tertiary tajo basin province c extends along the middle course of the tajo river with quartzofeldspathic metamorphiclastic sand modes qm60f33lt7 rs4rg21rm75 the sources are metamorphic rocks intruded by plutonites of the hesperian massif province d is quartzofeldspathic qm55f39lt6 with a dominance of phaneritic rock fragments rs5rg33rm62 and corresponds to the lower reaches of the tajo river where siliciclastic deposits of the neogene santarem lisboa basin are the main sources sands plot on provenance discrimination diagram qmflt within the recycled orogen field tajo river head and continentalblock fields upper middle and lower course in addition we have proven the usefulness of the rsrgrm diagram to discriminate the defined fluvial provinces originating from heterogeneous parent rock textures and mineralogy climate does not exert any strong influence on the petrogenesis of the tajo river drainage basin sand and erosion in the source areas may be described in terms of weathering limited denudation regime by contrast mixing with tributary supplies is the main process that modifies composition in the tajo river sand the establishment of fluvial provinces related to the main bedrock structural units reflects the great relevance of tributaries from each province in the generation of the tajo river sand and the low significance of inherited sandy load from previous provinces the abundance of granitoid rock fragments rsrgrm rg in fluvial sand of both tributaries and main channel of the tajo river drainage basin faithfully represents the relative abundance of granodiorite monzogranite bedrock exposure in each subbasin metasedimentary and metamorphic bedrock outcrop area is overrepresented by metamorphic rock fragments rsrgrm rm in both sand from tributaries and from the tajo main trunk river this is manifested by differences of 18 23 between means of metasedimentary outcrop area and the rsrgrm rm mean in the sand from provinces b and c d respectively sedimentary mainly carbonate outcrop area is underrepresented or not represented by sedimentary rock fragments rsrgrm rs in sand of the tajo river this underrepresentation causes a difference between means of sedimentary outcrop area and the rsrgrm rs mean of 21 17 1 and 10 7 in sands from province a b and c d respectively this fact confirms the rapid loss of these grains during transport because of their labile nature

surface current measurements using x band marine radar with vertical polarization in this paper the retrieval of sea surface current velocity from vertically polarized v pol x band marine radar data is presented three different methods including the iterative least square approach the normalized scalar product method and the polar current shell algorithm that have been used for horizontally polarized data are employed here a comprehensive comparison of the performance of the three methods is conducted using the radar images collected by the v pol radar deployed on the forschungsplattformen in nord und ostsee no 3 fino3 offshore research platform and the acoustic doppler current profiler adcp data in the north sea the results indicate that all three methods are capable of providing reliable current speed and direction measurements from v pol data with similar performance based on the experimental data for which the current magnitude is less than 0 5 m s the radar derived results agree best with the adcp data at a depth of 6 8 m with the root mean square difference for current velocity x and y components being 7 2 8 9 cm s the correlation coefficients between the radar derived and adcp measured current velocity components are as high as 0 87 0 93

the effects of source rocks and chemical weathering on the petrogenesis of siliciclastic sand from the neto river calabria italy implications for provenance studies plutonic and gneissic rocks of the sila massif in the uppermost portion of the neto drainage basin calabria southern italy weather and erode under a humid mediterranean climate during the development of weathering profiles a combination of chemical weathering and granular disintegration processes occurred chemical weathering involves a loss of both plagioclase mainly during grus generation and k feldspar mainly during soil formation this loss is attributed to transformation of plagioclase to clay minerals and to leaching and dissolution of k feldspar sand composition is quartzofeldspathic and nearly homogeneous along the main channel of the neto river even where the river cuts across a blanket of sedimentary cover thus fluvial transport does not alter sand composition within the neto drainage basin petrographic indices are effective in 1 discriminating between contributions from similar granite and gneiss source rocks qm f 2 relating the provenance of plutoniclastic and gneissiclastic sand found in the headwaters to grus horizons qm f q rg and 3 distinguishing between upstream first cycle and downstream multicycle sand q rg this last distinction is further emphasized by considering both aphanitic and phaneritic varieties of rock fragments rgrmrs diagram chemical weathering is the main sand producer within the regolithic environment in northern calabria in addition rapid erosion resulting from steep slopes removes weathered products and rapid and short transport leads to minimal sediment maturation in general the f q index is climate and relief dependent thus it should be used in conjunction with palaeoclimatic and palaeophysiographic evidence for provenance interpretations of ancient quartzofeldspathic sandstones

sensitivity of the atlantic meridional overturning circulation to the melting from northern glaciers in climate change experiments 1 a weakening of the atlantic meridional overturning circulation amoc in the next century is simulated by most state of the art coupled models but none of them accounted for land ice melting here we evaluate the impact of this melting on future climate projection using the ipsl cm4 coupled ocean atmosphere model for this purpose we use two different versions of the model one with a crude land ice melting parameterization and the other without the analysis compares results of experiments where atmospheric co2 increases by 1 yr performed with the two versions of this model the amoc is reduced by 47 when the melting of land ice is considered and represents an extreme melting scenario this reduction is of 21 without this melting it is shown that this difference in amoc impacts the northern hemisphere mostly through the sea ice cover feedback

seasonal speedup along the western flank of the greenland ice sheet it has been widely hypothesized that a warmer climate in greenland would increase the volume of lubricating surface meltwater reaching the ice bedrock interface accelerating ice flow and increasing mass loss we have assembled a data set that provides a synoptic scale view spanning ice sheet to outlet glacier flow with which to evaluate this hypothesis on the ice sheet these data reveal summer speedups 50 to 100 consistent with but somewhat larger than earlier observations the relative speedup of outlet glaciers however is far smaller 15 furthermore the dominant seasonal influence on jakobshavn isbrae s flow is the calving front s annual advance and retreat with other effects producing outlet glacier speedups an order of magnitude larger seasonal melt s influence on ice flow is likely confined to those regions dominated by ice sheet flow

effects of chemical weathering and sorting on the petrogenesis of siliciclastic sediments with implications for provenance studies the bulk chemical compositions mineralogy and mineral proportions of sands and muds of the mallacoota basin in southeastern australia reflect the composition of weathering profiles mantling source rocks rather than bedrock muds contain abundant clay minerals that are virtually absent from the source rocks but abundant in the weathering profiles sands are strongly enriched in quartz relative to source rocks even in the headwaters of the fluvial system demonstrating that feldspar destruction occurs by in situ chemical weathering within profiles and before detritus enters the fluvial system k feldspar is proportionally more abundant in fluvial sands than in source rocks because plagioclase is more rapidly destroyed than either quartz or k feldspar in weathering profiles subsequent erosion and sorting produce sands enriched in quartz with high k feldspar plagioclase ratios relative to source rocks the composition of plagioclase incorporated into the fluvial sands is also controlled by chemical weat

prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations abstract the exposed crust consists mainly of plagioclase 35 quartz 20 k feldspar 11 volcanic glass 12 biotite 8 and muscovite 5 quartz is a resistate thus feldspars and glass represent approximately 75 percent of the labile minerals the weathering characteristics of these constituents are summarized in the context of thermodynamic mass balance and kinetic considerations experimentally determined release rate constants were used to predict the proportions of ca na and k released by feldspars of plutonic rocks granites to gabbros to weathering solutions the chemical weathering trends of the weathered residues calculated from the kinetic data conform closely to the initial trends observed in some recent weathering profiles demonstrating the accuracy of the predictions since the weathering of feldspars is controlled by processes that should not change through geological time the relative release rates of ca na and k from the feldspars of granitic rocks can be calculated for future and past episodes of continental weathering experimentally determined release rate constants are not available for a wide range of volcanic glass compositions but the limited data indicate that compositional trends are predictable in weathering profiles developed on volcanic rocks the kinetic data available for rhyolitic glasses accurately predict the initial weathering trends observed in a recent rhyolite weathering profile

recent large increases in freshwater fluxes from greenland into the north atlantic 1 freshwater fw fluxes from river runoff and precipitation minus evaporation for the pan arctic seas are relatively well documented and prescribed in ocean gcms fluxes from greenland on the other hand are generally ignored altogether despite their potential impacts on ocean circulation and marine biology here we present a reconstruction of the spatially distributed fw flux from greenland for 1958 2010 we find a modest increase into the arctic ocean during this period fluxes into the irminger basin however have increased by fifty percent 6 3 0 5 km3 yr 2 in less than twenty years this greatly exceeds previous estimates for the ice sheet as a whole the rate of increase since 1992 is 16 9 1 8 km3 yr 2 the cumulative fw anomaly since 1995 is 3200 358 km3 which is about a third of the magnitude of the great salinity anomaly gsa of the 1970s if this trend continues into the future the anomaly will exceed that of the gsa by about 2025

changes in the velocity structure of the greenland ice sheet using satellite radar interferometry observations of greenland we detected widespread glacier acceleration below 66 north between 1996 and 2000 which rapidly expanded to 70 north in 2005 accelerated ice discharge in the west and particularly in the east doubled the ice sheet mass deficit in the last decade from 90 to 220 cubic kilometers per year as more glaciers accelerate farther north the contribution of greenland to sea level rise will continue to increase

character and origin of deep arenaceous weathering mantles on the bega batholith southeastern australia summary arenaceous weathering mantles on the bega batholith southeastern australia are similar to those described from europe by millot as in europe they have been formed by hydrothermal alteration of the parent rock and later by chemical weathering of biotites and feldspars but comparisons with nearby torfields shows that their distribution is determined largely by mineralogical variations in the parent rock unlike the examples cited by millot in the bega mantles kaolinite is the dominant clay mineral nonetheless these mantles seem to be contemporary not relict features and apparently formed under a temperate climate

sourceland controls on the composition of beach and fluvial sand of the northern tyrrhenian coast of calabria italy implications for actualistic petrofacies abstract the northern tyrrhenian margin of calabria in southern italy provides a natural laboratory for sampling sand at different scales small drainages first order rivers draining mountain ranges second order and marine environments beach to deep marine third order calabrian mountain ranges represent an uplifted and variable dissected thrust belt constituted by palaeozoic through pleistocene plutonic metamorphic ophiolitic carbonate and siliciclastic rocks the modern setting includes a mountainous coast having high rates of fluvial discharge and the deep marine paola basin the composition of modern fluvial and beach sands is useful for the interpretation of sediment transported into deeper water environments modern beach and fluvial sands of the northern tyrrhenian margin of calabria define three distinct petrologic provinces from north to the south 1 the lao littoral province has calclithite sand derived from erosion of dominantly carbonates of the southern apennines 2 the coastal range littoral province has quartzolithic sand derived from dominantly metamorphic schist and phyllite coastal range and 3 the santa eufemia littoral province has quarzofeldspathic sand derived from dominantly metamorphic coastal range and sila massif and plutono metamorphic mount poro provenances deep marine turbidites of the paola basin have basinwide quartzolithic turbidite sands having close compositional relations with coastal range littoral petrofacies only at the northern boundary of the paola basin calclithite turbidite sand record deep water dispersal of the lao littoral sands comparison of detrital modes from mainland to deep marine environments contribute to the models of dispersal pathways and geographical extension of actualistic sand petrofacies

decrease of river runoff in the upper waters of the eurasian basin arctic ocean between 1991 and 1996 evidence from δ18o data 1 measurements of the h218o h216o ratio of water from two sections crossing the eurasian basin in 1991 and 1996 show that the observed decrease in the freshwater contained in the upper waters of the eurasian basin during the 1990s is due to decrease in meteoric water mainly river runoff the decrease in meteoric water inventories between 1991 and 1996 calculated from balances of mass salinity 18o and po4 is about 3 meters and accounts for basically the entire freshwater change inferred from salinity budgets climatological data are used to ensure that the two sections can be considered to belong to the same hydrographic regime the data also suggest that in 96 the formation of sea ice from the upper waters in the amundsen basin was lower by about 1 meter 3 m in 1996 compared to 4 m in 1991

ocean wind fields retrieved from radar image sequences 1 the dependency of radar backscatter on the surface wind field is investigated using a nautical x band radar operating at grazing incidence and horizontal polarization in transmit and receive this resulted in development of an algorithm for wind retrieval from nautical radar image sequences the algorithm consists of two parts in the first part wind directions are extracted from wind induced streaks that are in line with the mean surface wind direction these streaks are visible in the temporal integrated radar images at scales between 100 and 500 m the orientation of the streaks is determined from the local gradients which are derived from the radar images smoothed and reduced to the appropriate scales in the second part wind speeds are derived from the backscatter of the temporal integrated radar image sequence and the radar retrieved wind direction the dependency of the radar backscatter on the local surface wind and geometry of the radar is parameterized by training a neural network the algorithm is applied to radar image sequences acquired by a nautical x band radar mounted aboard an offshore platform in the north sea the radar derived winds are validated by comparison to in situ wind data measured at the platform the comparison of wind directions resulted in a correlation of 0 99 with a standard deviation of 14 2 for wind speeds the correlation is 0 97 with a standard deviation of 0 85 m s 1 in contrast to traditional offshore wind sensors the retrieval of the wind field from the backscatter of the ocean surface makes the system independent of the sensors motion and installation height and reduces the effects due to platform induced blockage and turbulence effects

role of lichens in weathering of granodiorite in the sila uplands calabria southern italy this paper explores the role of five recurrent epilithic lichen species aspicilia intermutans nyl arnold xanthoparmelia pulla ach o blanco a crespo elix d hawksw lumbsch rhizocarpon lecanorinum anders tephromela atra huds hafellner and lecanora bolcana pollini poelt which encrust granodiorite spheroidal boulders exposed in the sila uplands calabria southern italy in weathering of plutonic rocks in a typical mountainous mediterranean environment a detailed investigation was carried out on the lichen rock interface of each species by comparing them mutually and with lichen free granodiorite samples for this purpose the lichen species were sampled together with the encrusted rock surface for detailed mineral petrographic analyses performed in thin and ultra thin sections optical and scanning electron microscopy of these sections and of bulk samples permitted us to highlight the peculiar modes of physical and chemical attacks of lichen thalli and hyphae on and into the substratum for each species crack systems often parallel to the outer rock surface appear often intruded by hyphae which cause rupture of primary minerals with detachment and progressive incorporation of their fragments into the thallus in particular the species l bolcana and t atra revealed an unexpected partly endolithic behavior presumably enhanced by the presence of rock fractures earlier generated by other physical breakage processes already affecting the spheroidal boulders in the sila mountains dissolution features often affect primary minerals even quartz that may show very peculiar patterns which are suggestive of a biologically induced control various phyllosilicate clay minerals were identified using sem eds microprobe analyses and ft ir spectroscopy which also enabled the identification of possible amorphous silica or quartz micrograins rhizocarpic acid and carotenoid at the encrusted granodiorite interface in contrast neither oxalic acids nor oxalates were detected

weathering of gneiss in calabria southern italy abstract the effects of weathering in a mediterranean climate on the mineralogy and microfabric of paleozoic gneiss of the sila massif calabria southern italy have been studied field observations show highly weathered rock forms a residual soil micromorphological and mineralogical properties of bedrock and saprolite show that the weathering process is characterized by at least two major stages having two distinct rock microfabrics in the first stage the morphological features of the original rock are preserved and weathering is manifested mainly by microfracturing and large portions of the rock remain unaltered the second stage of weathering involves further development of microcracks and progressive chemical attack on the minerals this latter stage occurs along both compositional and microstructural discontinuities with etch pitting of feldspar and neoformation of clay minerals and ferruginous products replacing feldspar biotite and iron bearing garnet the determination of quantitative petrographic indices provides a measure of the various stages of weathering

the interplay of geomorphic processes and soil development in an upland environment calabria south italy abstract five representative soil profiles outcropping in the area around the cecita lake calabria south italy were characterised by field work chemical and mineralogical analyses optical and scanning electron microscopy interactions among weathering pedogenesis and geomorphic processes are emphasised in an attempt to link the results obtained at different scales of observation the important role of topography in controlling soil development or removal by erosive processes is discussed in relation to the natural geomorphological context and the effects of human pressure both present day and relict features were recognised in the studied soils and discussed in terms of environmental conditions and climatic changes the chemical composition of volcanoclastic components identified in some soil horizons with andosol like field appearance coupled with pedogenetic features contributed useful chronological constraints for the reconstruction of late quaternary geomorphic events

dilution of the northern north atlantic ocean in recent decades declining salinities signify that large amounts of fresh water have been added to the northern north atlantic ocean since the mid 1960s we estimate that the nordic seas and subpolar basins were diluted by an extra 19 000 5000 cubic kilometers of freshwater input between 1965 and 1995 fully half of that additional fresh water about 10 000 cubic kilometers infiltrated the system in the late 1960s at an approximate rate of 2000 cubic kilometers per year patterns of freshwater accumulation observed in the nordic seas suggest a century time scale to reach freshening thresholds critical to that portion of the atlantic meridional overturning circulation

rapid changes in ice discharge from greenland outlet glaciers using satellite derived surface elevation and velocity data we found major short term variations in recent ice discharge and mass loss at two of greenland s largest outlet glaciers their combined rate of mass loss doubled in less than a year in 2004 and then decreased in 2006 to near the previous rates likely as a result of fast re equilibration of calving front geometry after retreat total mass loss is a fraction of concurrent gravity derived estimates pointing to an alternative source of loss and the need for high resolution observations of outlet dynamics and glacier geometry for sea level rise predictions

mass balance of the greenland ice sheet at dye 3 the mass balance of the greenland ice sheet a t dye 3 is estimated on the basis of 0 bserva tions of ice thickness accumulation rate surface velocities and surface strain rates the calculations indicate a rate of increase of surface elevation of 3 cm year with 95 confidence limits of 3 cm year and 9 cm year previous estimates of the mass balance of the greenland ice sheet by the same method reported large imbalances these are most probably due to lack of precise data and the use of quantities measured at the surface as representative of depth averaged quantities the most reliable observations indicate that the interior regions of the greenland ice sheet are at present thickening at a rate of a few centimetres per year a contributing cause for this may be the slow thinning of a bottom layer of relatively soft wisconsin ice resume bilan de masse de l lndlandsis groenlandais a dye 3 le bilan de masse est estime it partir des mesures d epaisseur taux d accumulation vitesses et vitesses de deformation superficielles le calcul don ne un epalss lssement de 3 cm an 1 avec un intervalle de confiance au seuil de 95 allant de 3 cm an 1 it 9 cm an i les estimations anterieures du bilan de l lndlandsis obtenues par la meme methode sont examinees on en deduit que les valeurs de bilan tres eloignees de l equilibre sont certainement dues au manque de donnees preclses et ou a i utilisation de donnees superficielles comme valeurs moyennes sur une

the influence of climate and topography on rock fragment abundance in modern fluival sands of the southern blue ridge mountains north carolina chemical weathering influences the detrital composition of sand size sediment derived from source areas subject to different amounts of precipitation in the coweeta basin north carolina of the grain types studied rock fragments are most sensitive to chemical degradation therefore their abundance is the best indicator of cumulative weathering effects destruction of sand size rock fragments by chemical weathering is a function of both the intensity and duration of chemical weathering experienced by grains in regoliths of the source area in the coweeta basin the intensity of chemical weathering is directly related to the climate via effective precipitation in individual subbasins whereas the duration of chemical weathering is inversely related to the relief ratio of the watershed therefore soils in watersheds with low relief ratios and high discharge per unit area experience the most extensive chemical weathering and sediments derived from these watersheds contain the lowest percentage of rock fragments the effects of climate alone cannot explain the systematic variation of rock fragment abundance in sediments from the coweeta basin the compositional imprint left on these sediments by chemical weathering is a function of both climate and topographic slope in the sediment source area

an empirical mode decomposition method for sea surface wind measurements from x band nautical radar data in this paper sea surface wind direction and speed are obtained from x band nautical radar images a data control strategy is proposed to distinguish rain free and rain contaminated radar data the radar data are decomposed by an ensemble empirical mode decomposition method into several intrinsic mode functions imfs and a residual a normalization scheme is applied to the first imf to obtain the amplitude modulation am component wind direction is determined from the residual for the rain free and high wind speed rain contaminated data and from the am portion of the first imf for the low wind speed rain contaminated data based on curve fitting a harmonic function wind speed is determined from a combination of the residual and the am part of the first imf for both rain free and rain contaminated data using a logarithmic relationship results employing ship borne radar and anemometer data collected in a sea trial off the east coast of canada are presented the root mean square differences for wind direction and speed measurements are 11 5 and 1 31 m s respectively compared with reference values from anemometers

inputs of glacially derived dissolved and colloidal iron to the coastal ocean and implications for primary productivity 1 glacial meltwaters draining shield bedrock under the greenland ice sheet gis contain 0 4 m total dissolved fe tdfe with an average flow weighted concentration of 53 nm the concentrations of 0 03 and 0 03 0 4 m fe vary over the ablation period with weighted means for each of these fractions being respectively 22 4 nm and 30 8 nm these concentrations are lower estimates as an adjacent larger glacier a more representative source of glacial meltwater had higher dissolved fe concentrations and reactions of meltwaters with proglacial sediments could also enhance dissolved fe concentrations this source of tdfe is additional to the reactive oxyhydr oxide phases identified by raiswell et al 2006 that are also introduced to adjacent polar seas from glaciers the fe concentrations in the shield bedrock underlying the gis are lower than those of other crustal rocks 4 0 cf 6 2 but we argue that these fe concentrations are not limiting on the total dissolved fe concentrations we measure the biogeochemical weathering processes operating on the subglacial debris and suspended sediment in our catchment are likely to be similar to those in other glaciated catchments therefore the meltwater fe concentrations reported here can be used to give a first estimate of global fluxes of meltwater dissolved fe to coastal polar waters a lower estimate of the global flux of tdfe from glacial meltwaters is 75 106 moles fe a this glacial meltwater input of fe to adjacent polar waters will be greatest around greenland where there are highest annual meltwater discharges however the greatest impact of this source of glacial meltwater fe is anticipated to be in antarctic high nutrient low chlorophyll hnlc waters where phytoplankton productivity is typically limited by availability of fe for antarctic waters the estimated meltwater fe tdfe input is about 10 of that suggested to come from sea ice melting but glacial inputs continue throughout the austral summer ablation period after sea ice melt is complete

wind retrieval from shipborne nautical x band radar data in this paper we study the retrieval of wind information from nautical x band radar data in contrast to previous studies where data from stationary research platforms were used this study focuses on data from a moving platform encountering a larger variety of conditions than a platform at a fixed location compared to traditional in situ sensors wind data derived from nautical radar images are much less susceptible to air flow distortion by the platform since the images cover a large area around the ship images collected with a standard nautical hh polarized x band radar operating at grazing incidence exhibit a single intensity peak in upwind direction the wind retrieval method developed here uses a harmonic function that is least squares fitted to the radar backscatter intensity as a function of antenna look direction the upwind direction is given by the direction that corresponds to the peak of the fitted function an empirical model function is derived to retrieve the wind speed from the average radar backscatter intensity contrary to wind retrieval methods that have been proposed before this approach is well suited for data acquired from a moving platform as it functions well even if the radar field of view is partially shadowed and does not require ship motion correction here we focus on data that were collected during two storms using the first storm to derive and the second to test the empirical model functions the method is validated using measurements from two ship based anemometers

geochemical signature of provenance in sand size material in soils and stream sediments near the tobacco root batholith montana u s a abstract trace element geochemistry of sandstones are being used to determine provenance we have conducted preliminary and limited experiments to determine to what extent daughter sands retain the geochemical signature of parent rocks six sets of first order stream sediments soils from adjacent slopes and a variety of parent rocks were collected from southwestern montana u s a sampling in a low relief area ensured that climate and residence time of soils on slopes could be eliminated as variables sand size fractions of stream sediments and soils and the corresponding parent rocks granodiorite quartz monzonite granite gneiss biotite tonalite gneiss and amphibolite were analyzed for most major elements and selected trace elements petrologic modal analysis of the parent rocks and the 0 25 0 50 mm fraction of each sand was done to monitor major mineralogic control if any on chemical compositions of the samples our data show that the abundances of the si and al in sediments do not discriminate provenance abundances of ca mg fe and ti may broadly distinguish between sands derived from metamorphic and igneous source rocks at least in the area studied differences in abundances of the ba and th and the ratio of la lu between granitic tonalitic and amphibolitic parent rocks are preserved in the daughter sediments that we studied however the size of the eu anomaly in the ree patterns of different daughter sediments is not diagnostic of parent rocks abundances of co and sc distinguish between sediments derived from felsic and mafic rocks a better provenance discrimination is obtained if the ratios la sc th sc la co ba sc and ba co are used petrologic modal data show that mineral contents and chemical compositions of parent rocks are compatible with each other the chemical composition of the sands may be roughly correlated to the petrological modal data but the abundances of some minor and trace elements of sediments cannot be inferred from modal mineralogy this is expected because these elements may concentrate in accessory minerals and or may weather out into aqueous or clay mineral fractions it is also compatible with conclusions of previous studies that some of these elements do not reside in sand size fractions of siliciclastic sediments

the great salinity anomaly in the northern north atlantic 1968 1982 the widespread freshening of the upper 500 800m layer of the northern north atlantic which this paper describes represents one of the most persistent and extreme variations in global ocean climate yet observed in this century though a range of explanations have been advanced to explain this event including in situ changes in the surface moisture flux this paper describes the great salinity anomaly as largely though not entirely an advective event traceable around the atlantic subpolar gyre for over 14 years from its origins north of iceland in the mid to late 1960s until its return to the greenland sea in 1981 1982 the overall propagation speed around this subpolar gyre is estimated at about 3cm s 1 of the total salt deficit associated with the anomaly as it passed south along the labrador coast in 1971 1973 about 72 109 tonnes a deficit equivalent to about two thirds of this figure 47 109 tonnes ultimately passed through the faroe shetland channel to the barents sea arctic ocean and greenland sea during the mid 1970s possible effects on deep water formation and on the representativeness of historical section data are discussed

wind direction estimation from rain contaminated marine radar data using the ensemble empirical mode decomposition method two ensemble empirical mode decomposition eemd based methods are presented to retrieve wind direction from rain contaminated x band nautical radar sea surface images each radar image is first decomposed into disparate intrinsic mode function imf components using 1 d eemd or 2 d eemd then the standard deviation of one imf component or the combination of several imf components as a function of azimuth is least squares fitted to a harmonic function to determine the wind direction tests of the proposed algorithms are conducted by employing radar and anemometer data collected in a sea trial during rain events off the east coast of canada the results show that compared with the 1 d discrete fourier transform based method both the 1 d and 2 d eemd based algorithms improve the wind direction results in rain events showing a reduction of 7 4 and 8 7 respectively in the root mean square difference with respect to the reference

weathering profiles in granitoid rocks of the sila massif uplands calabria southern italy new insights into their formation processes and rates abstract in this paper we characterized several weathering profiles developed on granitoid rocks in the sila massif upland calabria southern italy integrating detailed macro and micromorphological observations with physico mechanical field tests and petrographic mineralogical and geochemical analyses we focused our attention on the main weathering and pedogenetic processes trying to understand apparent discrepancies between weathering grade classes based on field description and geomechanical properties and two common weathering indices such as the micropetrographic index ip and the chemical index of alteration cia our results showed that sericite on plagioclase and biotite chloritization that represent inherited features formed during late stage hydrothermal alteration of granitoid rocks may cause an overestimation of the real degree of weathering of primary mineral grains under meteoric conditions especially in lower weathering grade classes moreover the frequent identification of fe mn oxides and clay coatings of illuvial origin rather than or in addition to those formed in situ both at the macro and microscale may also explain an overestimation of the weathering degree with respect to field based classifications finally some apparent inconsistencies between field geomechanical responses and chemical weathering were interpreted as related to physical weathering processes cryoclastism and thermoclastism that lead to rock breakdown even when chemical weathering is not well developed hence our study showed that particular caution is needed for evaluating weathering grades because traditional field and geochemical petrographic tools may be biased by inherited hydrothermal alteration physical weathering and illuvial processes on the basis of chronological constraints to soil formation obtained from a 42 ka old volcanic input mixed to granite parent materials detected in the soil cover of the sila massif upland a first attempt to estimate soil formation rates was achieved for different depths of corresponding weathering profile zones soil formation rates ranged from 0 01 0 07 mm a 1 for a and bw horizons weathering class vi to 0 04 0 36 mm a 1 for the underlying saprolite c and cr layers class v by comparing these results with the corresponding erosion rates available in the literature for the study area that range from

controls on modern fan morphology in calabria southern italy abstract alluvial fans are widespread throughout calabria but only a minority display evidence of current activity in order to understand if and to what extent fan types and their morphology are dependent on the physical environment including characteristics and processes of the depositional site and drainage basin we performed a series of discriminant analyses these analyses used as classification factors the presence or absence of fill in the feeder channel conditions of confinement by host terrain the dominant depositional process debris flow or sheetflood and morphometric attributes of fans and drainage basins as the discriminant function variables in general fan slope area and width length ratio and for basins melton s ruggedness number and source ratio were the most useful variables for classification best results were obtained by discriminating the types of fan deposits and the presence versus absence of fill in the feeder channel if the feeder source is singular fan morphology is controlled by constructional processes and is tightly linked to basin morphology on the other hand fan and basin morphology are also strongly dependent on the rock mechanical characteristics with hard rocks imparting to the basin a high ruggedness and to fans a high gradient larger fans however are those where sheetflooding predominates results of discriminant analysis based on fan and basin variables are much more significant than those based on fan variables only this means that the differences between characteristics of fan and basin systems are better defined than those between characteristics of fans only

the origin and implications of some erosional landforms etching is a mechanism of landform development involving two stages or phases first a regolith develops as a result of interaction between groundwaters and country rock the surface of contact between the two called the weathering front develops a relief as bedrock weaknesses are exploited by chemical corrosion second the regolith is stripped to expose the weathering front as an etch surface etch forms are widely distributed but are especially well developed and preserved in the relatively stable shield lands they range in scale from the plains and hills of inselberg landscapes to minor features such as boulders gutters basins flared slopes scarp foot depressions and pitted surfaces many etch forms have two ages one related to the period of subterranean preparation the other to the exposure of the erstwhile weathering front many are developed in a variety of rock types as well as in a considerable range of climatic settings etching carries several implications for landform interpretation

the relationship between geology and landforms along a coastal mountain front northern calabria italy the geomorphology of the central coastal range a north south trending horst along the west coast of northern calabria is governed largely by major faults fault scarps and the distribution of principal rock types as well as by a variety of slope processes operative in a mediterranean climate segments of the major rivers and streams have three principal orientations parallel to major faults in the study area northwest right oblique slip faults oldest e w oblique slip faults ne left oblique slip faults and north south right oblique normal faults youngest all of which cut pre tertiary metamorphic rocks mesozoic limestone miocene molasse and calcarenite small underfit alluvial fans composed chiefly of locally derived debris flow detritus are present at the mouths of large west flowing canyons some of which reach eastward to the crest of the mountain range not only do the north south normal faults displace rocks and structures of all orientations but they also make steep scarps in the small alluvial fans and in sediments of the coastal plain locally some of the scarps are buried by recent debris flow deposits incipient young rivers utilized the weaknesses along the major faults and cracks as avenues of erosion smaller streams and gullies generally flowed westward downflank of the north trending horst and incised thereby deep v shaped canyons some of them have captured older sw flowing canyons locally they were guided in other directions where they encountered faults or tectonic fractures the rocks present a varied resistance to erosion depending upon the degree of cementation by groundwater salts upon the orientation of the foliation and upon the rocks themselves thus mica schist with a relatively flat foliation forms nearly vertical sea cliffs but the sea cliffs are more gentle where the foliation is steep or dips towards the sea therefore downslope movements are facilitated by seaward slip on foliation schistosity bedding and fault surfaces and are evinced especially by large and deep pre holocene landslides sackung in phyllite having areal dimensions up to 2 km2 other downslope processes include surficial creep and soil slip particularly of highly fractured phyllite and schist block sliding and rock falls

weathering and pedogenesis in the sila grande massif calabria south italy from field scale to micromorphology abstract weathering and soil features in the upland landscapes developed on granitic terrains of the sila grande massif calabria south italy have been studied in this work the attempt to link field scale and micromorphological observations in order to better understand the main weathering processes and their controlling factors is revealed to be very powerful six soil profiles in the area around the cecita lake representative of different geomorphological units were characterised by field work optical microscopy and sem eds analysis a strong influence on weathering and pedogenesis by micro scale features of primary minerals and parent rock fabrics is shown key roles are played also by relief in the development and preservation or stripping of regolith soil mantles in relation to natural and man induced phenomena by time controlling rates and degree of development of the main weathering features by climate in terms of type and intensity of dominant processes

mineralogical and textural controls on the weathering of granitoid rocks summary the results obtained in several recent studies provide convincing evidence that potassium rich granitoid rocks are relatively more resistant to weathering than their less potassic counterparts this reflects the fact that microcline and orthoclase are more stable in most weathering environments than calcic plagioclase and biotite relatively slight differences in bulk rock chemical composition can lead to differential rates of weathering in areas of inhomogeneous granitoid terrain thereby leading to the development of topographic features such as inselbergs a second major control on the rate of weathering is rock permeability this is largely a function of degree of microfracturing and jointing in most circumstances grain size and other textural differences probably exert a minor influence on rates of chemical weathering although laboratory tests have shown they may profoundly affect physical strength parameters

mass balance of the greenland ice sheet from 1958 to 2007 we combine estimates of the surface mass balance smb of the greenland ice sheet for years 1958 to 2007 with measurements of the temporal variability in ice discharge d to deduce the total ice sheet mass balance during that time period we find a robust correlation r2 0 83 between anomalies in smb and in d which we use to reconstruct a continuous series of total ice sheet mass balance we find that the ice sheet was losing 110 70 gt yr in the 1960s 30 50 gt yr or near balance in the 1970s 1980s and 97 47 gt yr in 1996 increasing rapidly to 267 38 gt yr in 2007 multi year variations in ice discharge themselves related to variations in smb cause 60 20 more variation in total mass balance smb and therefore dominate the ice sheet mass budget copyright 2008 by the american geophysical union

freshwater distribution in the arctic ocean simulation with a high resolution model and model data comparison 1 a high resolution numerical simulation of the arctic ocean is analyzed in order to study the fate of river runoff and freshwater fluxes in the arctic ocean the model is driven by realistic winds and thermodynamic forcing from the european centre for medium range weather forecasting ecmwf reanalysis data set dye tracers have been added to visualize the pathways followed by low salinity water from the major arctic rivers and bering strait inflow the model is spun up using repeated forcing with the 1979 annual cycle for 20 years then the 1979 through 1998 atmospheric forcing is applied under the influence of the 1979 through early 1980s winds a large plume of river runoff exits the broad eurasian shelf seas along the lomonosov ridge starting in about 1985 the locus of shelf to basin transport shifts eastward to the alpha mendeleyev ridge complex this shift in the model output is related to changes in the sea surface height ssh fields which we attribute primarily to shifts in surface wind stresses model resolution runoff inputs and relaxation terms in the lena river delta region are analyzed in detail to expose issues with model performance at boundaries with freshwater inflow suggestions are made for improving future simulations of river runoff in basin scale models

messor barbarus ants as soil bioturbators implications for granulometry mineralogical composition and fossil remains extraction in somosaguas site madrid basin spain abstract few studies have inquired about the relationship between myrmecological activity and the granulometry and mineralogy of sediments of a palaeontological site the objectives of this article are to determine the sedimentological or mineralogical distinctions produced by ants of the species messor barbarus when excavating their nests and extracting grains and vertebrate fossil remains from the miocene palaeontological site of somosaguas madrid spain to evaluate the degree of taphonomic influence this myrmecological activity has on the fossil remains and to decide whether or not it can be used as a tool for palaeontological prospection results show that messor barbarus does not alter fossil remains when examined under a 10 binocular magnifying glass ants preferentially extract from the ant nest grains of medium sizes 0 25 2 mm compared to the non ant modified soils and also extract a higher quantity of feldspars these significant granulometric and mineralogical modifications should be considered when carrying out compositional sedimentological or stratigraphical studies since these can become biased and alter geological interpretations as provenance or palaeoclimatic signal grain size selection could be due to messor barbarus physical capacities or the use of clay particles as cementing elements in nests mineralogical distinction may be related to feldspars embayments and pits filled with finer material mainly smectites making transportation and pheromone impregnation easier results show that the ant mounds had increasing concentrations of fossil remains the nearer they were from the main excavation area therefore the study of ant mounds in potentially fossiliferous zones can indeed be used as a new method of palaeontological prospection

integrated assessment of changes in freshwater inflow to the arctic ocean we present an integrated and updated quantitative estimation of the river discharge and the meltwater flux and mass contributions from glaciers to the arctic ocean and to sea level rise the averag

analysis of internal wave signatures in marine radar data satellite images have long been used to study surface manifestations of internal waves iws more recently marine x band radar data have been employed to retrieve iw packet parameters marine radars have the advantage over satellite systems that their high temporal resolution enables the study of the iw evolution until today no method to automatically detect iw surface signatures in marine radar data has been suggested in this paper we present a new fully automated tool to retrieve iw signatures from marine radar image sequences first after various preprocessing steps the iw packet velocity is determined using a combination of localized radon transform and cross correlation techniques temporal averaging of the marine radar data significantly enhances the iw signatures the knowledge of the iw packet velocity is used to correct for the iw motion enabling us to extend the averaging period which further enhances the iw signal an iw motion correction is necessary because otherwise the iw signal would become smeared if the averaging period were much longer than the time it takes the iw to propagate between radar resolution cells the iw enhanced images are then utilized for the iw signature analysis here we identify local backscatter peaks and exploit the marine radar s high temporal resolution to distinguish signal from noise the resulting series of iw soliton maps provides information on changes in soliton wavelength velocity and backscatter intensity our marine radar iw signature analysis tool therefore offers a great opportunity of studying the spatiotemporal evolution of iws as they grow and decay

weathering erosion and sediment composition in a high gradient river calabria italy source rock lithology and immediate modifying processes such as chemical weathering and mechanical erosion are primary controls on fluvial sediment supply sand composition and chemical index of alteration cia of parent rocks soil and fluvial sand of the savuto river watershed calabria italy were used to evaluate the modifications of source rocks through different sections of the basin characterized by different geomorphic processes in a sub humid mediterranean climate the headwaters with gentle topography produce a coarse grained sediment load derived from deeply weathered gneiss having sand of quartzofeldspathic composition compositionally very different from in situ degraded bedrock maximum estimated cia values suggest that source rock has been affected significantly by weathering and it testifies to a climatic threshold on the destruction of the bedrock the mid course has steeper slopes and a deeply incised valley bedrock consists of mica schist and phyllite with a very thin regolith which provides large cobble to very coarse sand sediments to the main channel slope instability with an areal incidence of over 40 per cent largely supplies detritus to the main channel sand sized detritus of soil and fluvial sand is lithic estimated cia value testifies to a significant weathering of the bedrock too even if in this part of the drainage basin steeper slopes allow erosion to exceed chemical weathering the lower course has a braided pattern and sediment load is coarse to medium fine grained the river cuts across palaeozoic crystalline rocks and miocene siliciclastic deposits sand sized detritus contributed from these rocks and homogenized by transport processes has been found in the quartzolithic distal samples field and laboratory evidence indicates that landscape development was the result of extensive weathering during the last postglacial temperature maximum in the headwaters and of mass failure and fluvial erosional processes in the mid and low course copyright 2000 john wiley sons ltd

an algorithm for estimation of wave height from shadowing in x band radar sea surface images directional wave spectra and integrated wave parameters can be derived from x band radar sea surface images the calibration of such spectra has until now depended on various empirical and semiempirical methods which also require an external reference increasing the total expenses of operation a novel algorithm which is fully based on theory producing reasonable estimates of the significant wave height based on shadowing in the images has been now developed the method does not require any reference measurements and with that enables automatic calibration of spectra from radar sea surface images as well as the potential for reduced operational cost and increased accuracy of such wave monitoring systems promising results are obtained with data acquired at a test site in the north sea further work is however required to refine the algorithm and to test it under varying circumstances at various sites

lithological controls on hillslope sediment supply insights from landslide activity and grain size distributions the volumes rates and grain size distributions of sediment supplied from hillslopes represent the initial input of sediment delivered from upland areas and propagated through sediment routing systems moreover hillslope sediment supply has a significant impact on landscape response time to tectonic and climatic perturbations however there are very few detailed field studies characterising hillslope sediment supply as a function of lithology and delivery process here we present new empirical data from tectonically active areas in southern italy that quantifies how lithology and rock strength control the landslide fluxes and grain size distributions supplied from hillslopes landslides are the major source of hillslope sediment supply in this area and our inventory of 2800 landslides reveals that landslide sediment flux is dominated by small shallow landslides we find that lithology and rock strength modulate the abundance of steep slopes and landslides and the distribution of landslide sizes outcrop scale rock strength also controls the grain sizes supplied by bedrock weathering and influences the degree of coarsening of landslide supply with respect to weathering supply finally we show that hillslope sediment supply largely determines the grain sizes of fluvial export from catchments and that catchments with greater long term landslide rates deliver coarser material therefore our results demonstrate a dual control of lithology on hillslope sediment supply by modulating both the sediment fluxes from landslides and the grain sizes supplied by hillslopes to the fluvial system