modification and preservation of environmental signals in speleothems speleothems are primarily studied in order to generate archives of climatic change and results have led to significant advances in identifying and dating major shifts in the climate system however the climatological meaning of many speleothem records cannot be interpreted unequivocally this is particularly so for more subtle shifts and shorter time periods but the use of multiple proxies and improving understanding of formation mechanisms offers a clear way forward

late pleistocene paleoclimate in the black hills of south dakota from isotope records in speleothems abstract two coeval speleothems from the black hills are used to investigate 18 o and 13 c variations within reed s cave and reconstruct climate during the wisconsin glacial period from 82 000 to 24 000 years ago variation in growth rates between the two speleothems reveals a strong control of hydrology and surface vegetation on isotopic variability and response of 18 o to climate high resolution 18 o and 13 c data show that local environmental conditions can produce an offset of 18 o values of up to 4 in coeval speleothems but still reveal important climate events the transition from warmer to cooler periods results in an increase in 18 o of calcite 18 o ct in sample rc2 while in sample rc20 another equilibrium deposit coeval to part of the rc2 record 18 o ct is offset from rc2 by between 0 and 3 5 and shows much higher frequency isotopic variation speleothem rc2 records interglacial glacial transitions and interstadial events that are also present in speleothems from north america and europe spectral analysis of the 18 o ct records for both speleothems reveals periodicity at 1000 to 2000 years similar to millennial scale variability seen in the north atlantic sediments and the greenland ice cores

using fractal analysis to quantitatively characterize the shapes of volcanic particles 1 the shapes of volcanic particles reflect numerous eruptive parameters e g magma viscosity volatile content and degree of interaction with water and are useful for understanding fragmentation and transport processes associated with volcanic eruptions however quantitative analysis of volcanic particle shapes has proven difficult because of their morphological complexity and variability here a newly developed procedure for shape analysis based on fractal geometry is described and tested although volcanic particle shapes are not truly fractal their complexity can be effectively characterized in terms of fractal values pseudofractal dimensions reflecting morphological invariance over discrete ranges of scale using fractal data produced by dilation of a particle s two dimensional boundary a spectrum of fractal dimensions is calculated for each particle by taking the first derivative of the dilation data compared with fractal methods that express shape in terms of only one or two fractal dimensions typically derived from the slope of data on a richardson plot this technique results in better discrimination between samples in addition use of multiple fractal values allows incorporation of multivariate statistical analysis further strengthening the differentiating power of the technique this fractal spectrum technique yields promising results for samples of sideromelane shards from iceland and is likely to be effective at characterizing other kinds of volcanic particle shapes

flow resistance in ice covered alluvial channels this paper describes the influences of floating level ice covers on flow and bed load transport in alluvial channels and proposes a semi empirical procedure for calculating flow resistance in such channels the procedure can be applied in conjunction with several existing methods for estimating flow resistance in alluvial channels under open water conditions previously cover influence was poorly understood with the consequence that flow resistance calculations for ice covered alluvial channels entailed an inordinate amount of guesswork the cover influences described herein were determined from the results of experiments conducted with a laboratory flume the main findings of the flume experiments are that ice covers increase flow depth decrease bulk flow velocity increase dune length and significantly decrease bed load transport rate additionally it was found that sediment transport relationships developed for open water flow are applicable to ice covered flow provided they are used in conjunctio

deep sea fragmentation style of havre revealed by dendrogrammatic analyses of particle morphometry in 2012 the eruption of deep sea volcano havre produced an abundance of fine ash at a depth of 1000 m below sea level in this study the 2d shapes of havre ash grains retrieved from the seafloor were compared quantitatively with those of particles generated in a suite of different fragmentation experiments which used remelted rhyolitic rock and pumice from the eruption site a new statistical data analysis technique denoted as dendrogrammatic analysis of particle morphology dapm is introduced it is designed to compare large numbers of morphometric data sets containing shape information for a set of ash particles to group them by morphological similarities and to visualize these clusters in a dendrogram further steps involve t tests and equivalence tests and reveal morphometric differences as well as matching features the dapm suggests that the majority of havre ash was thermohydraulically produced by induced fuel coolant interaction a subset of ash particles features an elongated tube morphology their morphometry matches that of particles that were experimentally produced by a combination of shearing and quenching and we infer that the natural particles were formed by synextrusive ash venting

high resolution 3d analyses of the shape and internal constituents of small volcanic ash particles the contribution of sem micro computed tomography sem micro ct abstract the morphology of small volcanic ash particles is fundamental to our understanding of magma fragmentation and in transport modeling of volcanic plumes and clouds until recently the analysis of 3d features in small objects 20 m3 3 5 m in diameter can be successfully reconstructed and quantified in addition new functionalities of the blob3d software were developed to allow the particle shape factors frequently used as input parameters in ash transport and dispersion models to be calculated this study indicates that sem micro ct is very well suited to quantify the various aspects of shape in fine volcanic ash and potentially also to investigate the 3d morphology and internal structure of any object

carbon and oxygen isotope study of the active water carbonate system in a karstic mediterranean cave implications for paleoclimate research in semiarid regions abstract in a semiarid climatic zone such as the eastern mediterranean region annual rainfall variations and fractionation processes in the epikarst zone exert a profound influence on the isotopic compositions of waters seeping into a cave consequently the isotopic compositions of speleothems depositing from cave waters may show complex variations that need to be understood if they are to be exploited for paleoclimate studies this is confirmed by a four year study of the active carbonate water system in the soreq cave israel the 18o smow values of cave waters range from 6 3 to 3 5 the highest 18o values occur at the end of the dry season in waters dripping from stalactites and reflect evaporation processes in the epikarst zone whereas the lowest values occur in rapidly dripping fast drip waters at the peak of the rainy seasons however even fast drip waters are about 1 5 heavier than the rainfall above the cave which is taken to reflect the mixing of fresh with residual evaporated water in the epikarst zone 13c pdb values of dissolved inorganic carbon dic vary from 15 6 to 5 4 with fast drip waters having lower 13c values mostly 15 6 to 12 and higher dic concentrations relative to pool and stalactite drip water the low 13c values of fast drip waters and their supersaturation with respect to calcium carbonate indicates that the seepage waters have dissolved both soil co2 derived from overlying c3 type vegetation and marine dolomite host rock the 18o pdb values of various types of present day low magnesium calcite lmc speleothems range from 6 5 to 4 3 and 13c values from 13 to 5 5 and are not correlated with speleothem type an analysis of 18o values of present day calcite rafts and pool waters shows that they form in oxygen isotope equilibrium similarly the measured ranges of 13c and 18o values for all types of present day speleothems are consistent with equilibrium deposition at cave temperatures the 13c 18o range of contemporary lmc thus reflects the variations in temperatures and isotopic compositions of the presentday cave waters the 10 variation in the 13c values in waters can be modeled by a simple rayleigh calculation of the carbon isotope fractionation accompanying co2 degassing and carbonate precipitation these variations may obscure the differences in the carbon isotopic composition of speleothems that could arise when vegetation cover changes from c3 to c4 type plants this consideration emphasizes that it is necessary to characterize the full range of 13c values associated with contemporaneous speleothems in order to clarify the effects of degassing from those due to differing vegetation types isotopic studies of a number of different types of fossil lmc speleothems show many of them to exhibit isotopic trends that are similar to those of present day lmc but others show both higher and lower 18o ranges in particular the higher 18o range has been shown by independent age measurements to be associated with a period of drier conditions the results of the study thus indicate that it is necessary to work on a well calibrated cave system in semiarid climates and that the fossil speleothem record should be obtained from different types of contemporaneous deposit in order to fully characterize the 18o 13c range representative of any given climatic period

numerical model of flow in ice covered channel a two dimensional numerical model for a dune bed channel is extended to describe the flow structure in a channel with a bed of prescribed geometry and roughness and a free floating ice cover of known roughness the model involves solution of the reynolds averaged navier stokes equations with the k turbulence model which accounts for wall roughness it is validated against recent experiments in channels with simulated ice covers of varying roughness and is applied to estimate the effect of an ice cover on the flow in a dune bed channel

first evidence of a distal early holocene ash layer in eastern mediterranean deep sea sediments derived from the anatolian volcanic province article i nfo a hitherto unknown distal volcanic ash layer has been detected in a sediment core recovered from the southeastern levantine sea eastern mediterranean sea radiometric stratigraphic and sedimentological data show that the tephra here termed as s1 tephra was deposited between 8970 and 8690 cal yr bp the high silica rhyolitic composition excludes an origin from any known eruptions of the italian aegean or arabian volcanic provinces but suggests a prevailing central anatolian provenance we compare the s1 tephra with proximal to medial distal tephra deposits from well known mediterranean ash layers and ash fall deposits from the central anatolian volcanic field using electron probe microanalyses on volcanic glass shards and morphological analyses on ash particles we postulate a correlation with the early holocene dikkartin dome eruption of erciyes dag volcano cappadocia turkey so far no tephra of the central anatolian volcanic province has been detected in marine sediment archives in the eastern mediterranean region the occurrence of the s1 tephra in the south eastern part of the levantine sea indicates a wide dispersal of pyroclastic material from erciyes dag more than 600 km to the south and is therefore an important tephrostratigraphical marker in sediments of the easternmost mediterranean sea and the adjacent hinterland

fractal analysis of fracture patterns using the standard box counting technique valid and invalid methodologies abstract on the basis of results of simple box counting analysis it has been suggested in several recent publications that natural fracture patterns are fractal fractal patterns are characterized by self similarity of structure on a range of scales and provide straight line distributions on box counting plots new analysis of a fracture pattern that provided the most convincing straight line box counting curve previously published shows that the curve is non linear and therefore that the fracture pattern is not fractal non linear box counting curves are also characteristic of other natural fracture patterns analysed but spurious linear curves can be obtained if the area analysed extends beyond the mapped area

mechanisms of hydrovolcanic pyroclast formation grain size scanning electron microscopy and experimental studies pyroclasts produced by explosive magma water interactions are of various sizes and shapes data from analysis of over 200 samples of hydrovolcanic ash are interpreted by comparison with experimentally produced ash grain size and scanning electron microscopy sem reveal information on the formation of hydrovolcanic pyroclasts strombolian explosions result from limited water interaction with magma and the pyroclasts produced are dominantly centimeter sized with increasing water interaction hydrovolcanism increases in explosivity to surtseyan and vulcanian activity these eruptions produce millimeter to micron sized pyroclasts the abundance of fine ash 63 m diameter increases from 5 to over 30 percent as water interaction reaches an explosive maximum this maximum occurs with interactions of virtually equal volumes of melt and water five dominant pyroclast shape types determined by sem result from hydrovolcanic fragmentation 1 blocky and equant 2 vesicular and irregular with smooth surfaces 3 moss like and convoluted 4 spherical or drop like and 5 plate like types 1 and 2 dominate pyroclasts greater than 100 m in diameter types 3 and 4 are typical of fine ash type 5 pyroclasts characterize ash less than 100 m in diameter resulting from hydrovolcanic fragmentation after strong vesiculation fragmentation mechanisms observed in experimental melt water interactions result from vapor film generation expansion and collapse fragments of congealed melt are products of several alternative mechanisms including stress wave cavitation detonation waves and fluid instability mixing all result in rapid heat transfer these mechanisms can explain the five observed pyroclast shapes stress wave fracturing cavitation of the melt results from high pressure and temperature gradients at the melt water interface simultaneous brittle fracture and quenching produces type 1 pyroclasts type 2 develops smooth fused surfaces due to turbulent mixing with water after fracture and before quenching fluid instabilities promote turbulent mixing of melt and water and produce fine ash this kind of fragmentation occurs during high energy explosions the increased melt surface area due to fine fragmentation promotes high efficiency heat exchange between the melt and water shapes of resulting pyroclasts are determined by maximum surface area type 3 and surface tension effects type 4 type 5 pyroclasts result from nearly simultaneous vesicle burst and melt water fragmentation

towards fast and routine analyses of volcanic ash morphometry for eruption surveillance applications the morphometry of volcanic ash produced by explosive eruptions yields ample information on fragmentation processes e g magmatic vs magma water interactions and on transport and sedimentation mechanisms most previous works on volcanic clast morphometry focused on the apparent 2d projected shape of ash grains here termed apash to infer processes and eruptive styles however textural analyses of ash grains has remained a long and tedious task that made such approaches inappropriate for eruption surveillance duties in this work we show that new technological advances on automated dispersion of granular materials imaged with a camera coupled microscope and enhanced computer capabilities enable fast and high resolution image acquisition of thousands of ash grains that resolve this limitation with a morpho grainsizer designed for such fast and routine measurements we perform a series of apash analyses on selected ash fractions of tephra deposits from known eruptive styles we record the size aspect ratio circularity and convexity of apash images and assess resolution reproducibility minimum population size and total analytical duration and offer recommendations for the reporting of apash data for inter laboratory comparisons to avoid fractal geometry concerns our analyses are carried out at constant size range 250 300 m and optical magnification 5 on 3000 grains per samples collected from homogenized samples results from the andesitic 1999 ongoing eruption of tungurahua volcano ecuador show that ash particles from the moderate 2001 phase are relatively equant and convex in shape while the stronger 2006 subplinian phase produced ash grains with more elongated less circular and less convex apash signatures ash grains from a basaltic scoria cone forming eruption show even more ragged apash characteristics overall our protocol allows obtaining accurate and reproducible morphometric measurements that reveal subtle variations of the morphological signature and the short duration 1 8 hours of the whole analytical process renders high resolution analyses of ash shape achievable for volcano surveillance applications this research ultimately aims to set up a morphometric database of apash results for well defined eruptive styles in order to interpret on a short term basis any apash data from active volcanoes for monitoring purposes

ice influences on channel stability insights from missouri s fort peck reach this paper presents insights from a comprehensive study of river ice influences on alluvial channel bathymetry and stability the study entailed unique wintertime fieldwork along the fort peck reach of the missouri river the insights show how ice formation presence and breakup can influence channel stability in several important ways especially when channels must convey substantial water flow during winter ice may hasten the migration of channel bends cause transient scour and sediment deposition during winter and induce cyclic shifts of flow thalweg through sinuous braided subreaches the insights are of direct significance for engineering activities along the missouri s fort peck reach and other alluvial channels subject to frigid winters they also are significant for understanding the frigid winter habitat of aquatic life in such channels

disequilibrium carbon and oxygen isotope fractionation in recent cave calcite comparison of cave precipitates and model data abstract speleothem proxy data provide important information in continental palaeo climate research due to their precise chronology and wide geographic distribution despite a continuously growing number of field and numerical studies designed to study stable isotope fractionation effects many aspects remain a matter of debate here carbon and oxygen isotope ratios from cave drip water and calcite precipitates sampled on watch glasses in the bunker cave western germany are compared with the values expected for isotopic equilibrium furthermore the field data are compared with the results of a numerical model simulating stalagmite growth and stable isotope ratios two drip sites with different drip rates were investigated drip site ts 1 is characterised by a high drip rate and drip water of this site is characterised by a high saturation index with respect to calcite ts 1 shows no evidence of prior calcite precipitation conversely drip site ts 8 shows a low drip rate and drip water from this site is characterised by a low saturation index ts 8 shows evidence of prior calcite precipitation whereas the mean 13 c dic values of the drip water are significantly different between the two drip sites the mean 18 o drip water values are similar calcite precipitation rates are higher at watch glass site u i corresponding to drip site ts 1 this is probably due to the higher si calcite and drip rate the 18 o and 13 c values of the calcite precipitated on watch glasses u iv corresponding to drip site ts 8 are significantly higher than those of the calcite collected on watch glasses u i calcite precipitation occurs close to isotopic equilibrium at watch glass site u i whereas the calcite precipitated at watch glass site u iv shows clear evidence of isotopic disequilibrium the results suggest that cave calcites precipitated at lower drip rates have higher 13 c and 18 o values than predicted by equilibrium precipitation furthermore our data show that stalagmites from the same cave which are fed by drip water with similar 18 o values may have different 18 o calcite values the 13 c and 18 o values predicted by the numerical model are generally lower by 1 9 and 0 8 respectively than those of the natural cave calcite nevertheless the first order trends observed in the cave data are well reproduced by the model the offset between cave and model data is probably due to the fractionation factors used in the model

optical modeling of volcanic ash particles using ellipsoids the single scattering properties of volcanic ash particles are modeled here by using ellipsoidal shapes ellipsoids are expected to improve the accuracy of the retrieval of aerosol properties using remote sensing techniques which are currently often based on oversimplified assumptions of spherical ash particles measurements of the single scattering optical properties of ash particles from several volcanoes across the globe including previously unpublished measurements from the eyjafjallajokull and puyehue volcanoes are used to assess the performance of the ellipsoidal particle models these comparisons between the measurements and the ellipsoidal particle model include consideration of the whole scattering matrix as well as sensitivity studies on the point of view of the advanced along track scanning radiometer aatsr instrument aatsr which flew on the envisat satellite offers two viewing directions but no information on polarization so usually only the phase function is relevant for interpreting its measurements as expected ensembles of ellipsoids are able to reproduce the observed scattering matrix more faithfully than spheres performance of ellipsoid ensembles depends on the distribution of particle shapes which we tried to optimize no single specific shape distribution could be found that would perform superiorly in all situations but all of the best fit ellipsoidal distributions as well as the additionally tested equiprobable distribution improved greatly over the performance of spheres we conclude that an equiprobable shape distribution of ellipsoidal model particles is a relatively good yet enticingly simple approach for modeling volcanic ash single scattering optical properties

daily response of drip water isotopes to precipitation in liangfeng cave guizhou province sw china abstract oxygen isotope 18o is one of the most commonly used palaeoclimate proxies and monitoring their modern evolutionary processes is very significant for palaeoclimate reconstruction in this study drip water samples are daily collected from two drip sites in liangfeng cave guizhou province sw china between june 2008 and june 2010 the stable hydrogen and oxygen isotopes of these samples and the contemporary precipitation samples are measured the relationships between the isotopes and the local air temperature precipitation and relative humidity are analysed the results show that the hydrogen and oxygen isotopic compositions of precipitation have obvious seasonal variations in the study area lower in the rainy season and higher in the dry season the local meteoric water line lmwl is d 8 64 18o 17 44 precipitation is the only source of cave drip water and its oxygen isotope signals are reflected in the two drip waters sd slower drip rate and previously called 1 and fd faster drip rate and previously called 5 however the amplitude of the drip water oxygen isotope variation is much smaller than that of the precipitation i e homogenization occurs to some extent however there are significantly different responses to precipitation between the two drip sites the response time of sd to precipitation is much longer than that of fd the amplitude of oxygen isotope variation in sd where the isotopic data deviate from the lmwl to a higher degree is much smaller than that in fd a comparison of these isotopic differences with previous research in the same cave indicates that the isotopic differences between the two drip waters result from different flow paths the oxygen isotope signal in cave drip water perhaps mainly reflects summer monsoon information in the study area the speleothems fed by drip waters e g fd with shorter response time to precipitation may be more suitable for high resolution palaeoclimate research moreover the d excess from speleothem fluid inclusion has the potential to be used as an indicator of relative humidity of local air

sediment transport under ice cover a method for calculating sediment transport in ice covered flows is developed laboratory data on bed form frictional characteristics and sediment transport are obtained for equivalent free surface and covered flows comparison of the data leads to the conclusion that the lower layer in a covered flow can be treated as a free surface flow for the purpose of calculating bed load transport using the flow characteristics calculated from the k e turbulence model and a conventional bed load equation the sediment transport for covered flows can be obtained the method was verified using measured data

the transfer of seasonal isotopic variability between precipitation and drip water at eight caves in the monsoon regions of china abstract this study presents new stable isotope data for precipitation 18op and drip water 18od from eight cave sites in the monsoon regions of china mrc with monthly to bi monthly sampling intervals from may 2011 to april 2014 to investigate the regional scale climate forcing on 18op and how the isotopic signals are transmitted to various drip sites the monthly 18op values show negative correlation with surface air temperature at all the cave sites except shihua cave which is opposite to that expected from the temperature effect in addition although the monthly 18op values are negatively correlated with precipitation at all the cave sites only three sites are significant at the 95 level these indicate that due to the various vapor sources a large portion of variability in 18op in the mrc cannot be explained simply by either temperature or precipitation alone all the thirty four drip sites are classified into three types based on the 18od variability about 82 of them are static drips with little discernable variation in 18od through the whole study period but the drip rates of these drips are not necessary constant their discharge modes are site specific and the oxygen isotopic composition of the stalagmites growing from them may record the average of multi year climatic signals which are modulated by the seasonality of recharge and potential effects of evaporation and in some cases infiltration from large rainfall events about 12 of the thirty four drip sites are seasonal drips although the amplitude of 18od is narrower than that of 18op the monthly response of 18od to coeval precipitation is not completely damped and some of them follow the seasonal trend of 18op very well these drips may be mainly recharged by present day precipitation mixing with some stored water thus the stalagmites growing under them may record portions of the seasonal climatic signals embedded in 18op about 6 of the thirty four drip sites are medium variability drips with constant and relatively low 18od values in the wet season but with variable and relatively high 18od values in the dry season reflecting flow switching in the karst or evaporation inside the cave

furthering the investigation of eruption styles through quantitative shape analyses of volcanic ash particles abstract volcanic ash morphology has been quantitatively investigated for various aims such as studying the settling velocity of ash for modelling purposes and understanding the fragmentation processes at the origin of explosive eruptions in an attempt to investigate the usefulness of ash morphometry for monitoring purposes we analyzed the shape of volcanic ash particles through a combination of 1 traditional shape descriptors such as solidity convexity axial ratio and form factor and 2 fractal analysis using the euclidean distance transform edt method we compare ash samples from the hydrothermal eruptions of iwodake japan in 2013 tangkuban perahu indonesia in 2013 and marapi sumatra indonesia in 2015 the dome explosions of merapi java indonesia in 2013 the vulcanian eruptions of merapi in 2010 and tavurvur rabaul papaua new guinea in 2014 and the plinian eruption of kelud indonesia in 2014 particle size and shape measurements were acquired from a particle size analyzer with a microscope camera attached to the instrument clear differences between dense blocky particles from hydrothermal or dome explosions and vesicular particles produced by the fragmentation of gas bearing molten magma are well highlighted by conventional shape descriptors and the fractal method in addition subtle differences between dense blocky particles produced by hydrothermal explosions dome explosions or quench granulation during phreatomagmatic eruptions can be evidenced with the fractal method the combination of shape descriptors and fractal analysis is therefore potentially able to distinguish between juvenile and non juvenile magma which is of importance for eruption monitoring

the use of shallow dripwater as an isotopic marker of seepage in karst areas a comparison between western sicily italy and the harz mountains germany abstract the isotopic signature of slow flowing dripwater collected in caves located in western sicily italy was determined for evaluating its possible use as an isotopic tracer of the local groundwater recharge these spot measures were compared with a longer series of local rain and spring compositions and with other samples taken under different hydrogeological conditions in caves of the harz mountains northern germany the slow flowing dripwater from sicily showed 18 o d ratios similar to those of local rain and groundwater demonstrating that these three are all parent waters a parallel similarity was found in the vertical isotopic gradient 18 o of the three groups of water accounting for their common meteoric origin in the colder harz region dripwater spring water and rain have the same 18 o d ratio but fast flowing dripwater infiltrating through open cracks is significantly enriched in lighter isotopes and representative of short residence time percolation these results lead to the conclusion that dripwater even if collected as spot samples can be considered as a good isotopic marker of the average local groundwater recharge on the condition that only slow diffused drips due to seepages are sampled

isotopic characterization of cave environments at varying altitudes on the eastern adriatic coast croatia implications for future speleothem based studies abstract an important step in the implementation of paleoclimate reconstructions from speleothems cave carbonate deposits is to evaluate the sensitivity of the host cave environment to regional climate accordingly we studied three caves at different altitudes 74 m 570 m and 1250 m a s l along a transect from the dalmatian islands to velebit mountain peaks in coastal croatia to characterize their environments in terms of each cave s suitability to host speleothems that would be capable of yielding robust paleoclimate reconstructions we conducted cave microclimate 2 years and dripwater 1 year monitoring and analysed the isotopic composition of precipitation cave dripwater and modern spelean calcite as for the water isotopic imprints the isotopic values of meteoric waters reaching the two lower altitude caves in spite of an altitude difference of 500 m lie on local meteoric water lines lmwls of similar slope and intercept 2 h 6 61 18 o 4 92 and 2 h 6 69 18 o 6 86 their slopes lower than that of gmwl indicate enhanced evaporation during the warm season as expected the lmwl of the highest cave region 2 h 7 83 18 o 14 45 resembles the slope of the gmwl but the values of deuterium excess obtained for all three caves between 15 2 and 16 6 match that of western mediterranean sourced waters 15 monthly d excess values suggest atlantic sourced air masses can reach the sites throughout the year but never dominate the rainfall composition the altitude effect was noted both in precipitation and in dripwater isotopic composition but with notably different 18 o 100 m gradients 0 33 and 0 11 respectively stable isotope variations of the dripwaters in all caves were attenuated in relation to the rainwater even those of the drip sites with fracture flow behaviour based on stable cave microclimate conditions relatively steady discharges and modern calcite apparently precipitated at or close to isotopic equilibrium with dripwater the two caves at lower altitudes show the greatest potential for future paleoclimate studies the cave at the highest altitude experiences large cave air temperature amplitudes 5 3 c and pronounced ventilation making the isotopic signal susceptible to kinetic fractionation which might preclude quantification of environmental changes but on the other hand it accentuates isotopic events making them easier to identify

hydrogeochemical and climatic interpretations of isotopic signals from precipitation to drip waters in liangfeng cave guizhou province china oxygen isotope is a commonly used proxy for paleoclimatic studies on stalagmites in order to understand the transmission of isotopic signals from precipitation to stalagmites meteorological indexes of exterior and interior cave and hydrogeochemical proxies of drip waters in liangfeng cave have been monitored from april 2011 to april 2013 samples of rain and drip waters from three drip sites designated as 1 5 and 6 are collected for hydrogen and oxygen isotopes testing results show that the amount weighted mean 18o value of rain in the first year may 9 2011 to may 1 2012 is lighter than that in the second may 30 2012 to may 2 2013 this may result from different proportions of the pacific indian ocean source moistures the arithmetic mean 18o values of 1 5 and 6 are similar to the multi year amount weighted mean 18o value of precipitation hydrogeochemical analyses of drip waters reveal that the discharge rates increase in the order of 6 1 5 and that water rock reaction fresh old water mixing and co2 degassing exert dominant controls on seepage waters in aquifers hard infiltration of rain during dry season with heavier 18o value due to its small amount may cause lower mean drip water 18o values e g 1 evaporation during the dripping and exuding processes in dry season may result in heavier mean drip water 18o values e g 6 considering calcite depositing mostly during dry season we compare the mean 18o values of drip waters during dry season between the first and second years differences exist and share the same trend with rain the results indicate that drip waters can inherit oxygen isotopic signals of rain but it is critical to have a replication test on 18o records of stalagmites from the same cave for paleoclimatic studies what s more 18o values in stalagmites feeding by drip waters that have no little annual 18o variations may be useful to paleotemperature reconstructions

identifying magma water interaction from the surface features of ash particles the deposits from explosive volcanic eruptions those eruptions that release mechanical energy over a short time span1 are characterized by an abundance of volcanic ash2 3 this ash is produced by fragmentation of the magma driving the eruption and by fragmenting and ejecting parts of the pre existing crust host rocks interactions between rising magma and the hydrosphere oceans lakes and ground water play an important role in explosive volcanism4 5 because of the unique thermodynamic properties of water that allow it to very effectively convert thermal into mechanical energy although the relative proportion of magma to host rock fragments is well preserved in the pyroclastic rocks deposited by such eruptions it has remained difficult to quantitatively assess the interaction of magma with liquid water from the analysis of pyroclastic deposits2 3 4 5 here we report the results of a study of natural pyroclastic sequences combined with scaled laboratory experiments we find that surface features of ash grains can be used to identify the dynamic contact of magma with liquid water the abundance of such ash grains can then be related to the water magma mass ratios during their interaction

quantitative discrimination of magma fragmentation and pyroclastic transport processes using the fractal spectrum technique abstract the morphology of volcanic particles can yield insight into magma fragmentation transport processes and style of eruption however the complexity and variability of volcanic particle shapes make quantitative characterization difficult the technique applied in this study is based on fractal geometry which has been successfully used to characterize a wide variety of particles and shapes here fractal data is produced by dilation of the 2 d particle boundary to produce a full spectrum of fractal dimensions over a range of scales for each particle multiple fractal dimensions which can be described as a fractal spectrum curve are calculated by taking the first derivative of data points on a standard richardson plot use of multiple fractal dimensions results in more effective discrimination than expressions of shape based on one or two fractal dimensions quantitative comparisons are carried out using multivariate statistical techniques such as cluster and principal components analysis applications to samples from well documented eruptions e g mt st helens 1980 tambora 1815 surtsey 1963 64 indicate that the fractal spectrum technique provides a useful means of characterizing volcanic particles and can be helpful for identifying the products of specific fragmentation processes volatile exsolution phreatomagmatic quench granulation and modes of volcanic transport deposition tephra fall pyroclastic flow blast surge

fragmentation versus transportation mechanisms in the pyroclastic sequence of monte pilato rocche rosse lipari italy abstract monte pilato is a rhyolitic pumice cone formed about 1400 years ago during the last volcanic activity which occurred at lipari its activity consisted of numerous explosive episodes ending with the extrusion of the rocche rosse obsidian lava flow we have identified nine different pyroclastic lithofacies of which four main lithofacies represent 90 of the erupted products they include 1 deposits consisting of decimeters to meters thick well sorted graded beds of pumice lapilli which are of fall origin 2 massive deposits consisting of decimeters thick beds of pumice lapilli in an ash matrix interpreted as being of pyroclastic flow origin 3 deposits of centimeters thick ash beds of surge origin 4 decimeter thick fine ash layers with scattered subcentimetric accretionary lapilli of turbulent flow origin the complex grain size distributions of the main lithofacies were distinguished using a multivariate statistic analysis r mode factor analysis variations of the grain size characteristics in relation to the distance from the vent area have been investigated in order to discriminate the roles played by fragmentation and transportation processes in the lithofacies 1 fall deposits the grain size distribution is always unimodal and varies from a rosin type distribution near the vent to a gaussian one in the distal outcrops this is caused by the transport process and the different particle trajectories in lithofacies 2 3 and 4 the grain size distributions are always polymodal the polymodality is not caused by preferential processes occurring during transportation but seems rather to be connected with the original fragmentation of the pyroclastic material the pumice lapilli present both in lithofacies 1 and 2 have mean vesicularity index values always in excess of 65 and the value is homogeneous throughout the sample these data suggest that for these two lithofacies the pumice lapilli originated from exsolution of magmatic gases in contrast the fine ash particles in lithofacies 2 and also the main mode of lithofacies 3 and 4 deposits show typical features of hydromagmatic fragmentation processes the grain size population is always centered at 4 5 0 032 0 064 mm and interestingly the same grain size has been obtained recently zimanowski et al 1991 for fragments produced by experimental magma water interaction field and laboratory data suggest that during monte pilato rocche rosse eruptions magmatic and hydromagmatic mechanisms were frequently operative at the same time

soil and karst aquifer hydrological controls on the geochemical evolution of speleothem forming drip waters crag cave southwest ireland abstract in recent years there has been increased interest in cave speleothems as archives of palaeoclimate monitoring of rainfall and soil and karst water chemistries was performed at crag cave castleisland co kerry southwest ireland in august 1997 and january 1998 in order to understand temporal and spatial variations in karst water hydrology and chemistry and their implications for interpreting the potential palaeohydrological signal preserved by speleothems at this site temporal variations in karst water drip rates and geochemistry allow drips to be classified by hydrological response to rainfall and the associated processes of dilution piston flow source change and prior calcite precipitation during aquifer throughflow evolution from soil matrix and preferential flow solutions has also been determined to exert an important control on karst water chemistries as a result of these findings we present hydrogeochemical models and plumbing diagrams that delineate the controls on karst water evolution at a number of sampling locations within the cave at this site we propose that a palaeohydrological signal may be recorded by crag cave speleothems that may be interpreted via the study of mg ca ratios in speleothems linked to monitoring of modern drip water chemistry

use of fractal analysis for discrimination of particles from primary and reworked jokulhlaup deposits in se iceland abstract the morphology of sideromelane particles from jokulhlaup deposits in southeastern iceland has been studied by fractal analysis to assess post depositional changes associated with reworking fractal dimensions of particle boundaries were calculated from data obtained by the caliper and dilation methods most particles exhibit multifractal relationships with a textural d1 and structural d2 fractal dimension particles from primary jokulhlaup deposits have significantly greater textural and structural fractal dimensions compared to reworked deposits differences in the fractal dimensions indicate that reworking in the littoral zone has reduced both the amount of fine scale features on particle surfaces and the complexity of the overall particle shapes the caliper and dilation methods yield similar values of textural fractal dimension for each particle for the same particles the dilation method yields higher values of structural fractal dimension reworked particles used in this study can be effectively discriminated from primary particles using a combination of d1 and d2 fractal dimensions the results indicate that fractal analysis provides a useful quantitative characterization of complex volcanic particles and can be utilized to examine aspects of particle origin transport and deposition

turbulence structure in an ice covered sand bed river although many high latitude rivers are characterized by seasonal ice cover few empirical studies have examined the effect of surface ice on the turbulent properties of the underlying flowing water this study presents three dimensional turbulence measurements obtained with an acoustic doppler velocimeter adv in a straight reach of an ice covered sand bed river the statistical properties of three dimensional turbulence were analyzed it is shown that the spatial structure of the flow was nonuniform due to nonuniformity of the ice cover in the cross stream direction and due to the riverbed geometry these factors are responsible for the complex spatial structure of the flow field which limits the predictability of available physical models observed distributions over depth of reynolds stresses and mean streamwise velocities generally conform with distributions derived from piecewise solutions of a two dimensional flow model at least in the central part of the flow but observed and expected values of some parameters differ substantially we have hypothetically addressed these differences to the effect of flow stratification and the values of a stratification parameter have been estimated the velocity measurements allowed to analyze the coherent structures near the bed and beneath the ice cover their spatial scales were evaluated to be as large as the river depth for ejections and 0 7 0 8 times the river depth for sweeps whereas low frequency variations of the streamwise velocity were observed to have scales of two to four river depths

grain shape of basaltic ash populations implications for fragmentation here we introduce a new quantitative method to produce grain shape data of bulk samples of volcanic ash and we correlate the bulk average grain shape with magma fragmentation mechanisms the method is based on automatic shape analysis of 2d projection ash grains in the size range 125 63 m loose bulk samples from the deposits of six different basaltic eruptions were analyzed and 20 000 shape measurements for each were obtained within 45 min using the particle insight dynamic shape analyzer pidsa we used principal component analysis on a reference grain dataset to show that circularity rectangularity form factor and elongation best discriminate between the grain shapes when combined the grain population data show that the studied eruptive environments produce nearly the same range of grain shapes although to different extents our new shape index the regularity index ri places an eruption on a spectrum between phreatomagmatic and dry magmatic fragmentation almost vesicle free surtseyan ash has an ri of 0 207 0 002 2 whereas vesiculated hawaiian ash has an ri of 0 134 0 001 2 these two samples define the end member ri while two subglacial one lacustrine and another submarine ash sample show intermediate ris of 0 168 0 002 2 0 175 0 002 2 0 187 0 002 2 and 0 191 0 002 2 respectively the systematic change in ri between wet and dry eruptions suggests that the ri can be used to assess the relative roles of magmatic vs phreatomagmatic fragmentation we infer that both magmatic and phreatomagmatic fragmentation processes played a role in the subglacial eruptions

monitoring bunker cave nw germany a prerequisite to interpret geochemical proxy data of speleothems from this site summary monitoring cave environments is important to understand processes in karst systems if stalagmites from a specific cave are used as archives of past climate variability a quantitative understanding of the soil karst speleothem system is crucial the monitoring program performed in bunker cave nw germany which includes monthly collection of climatological data as well as air and water samples from the cave and the overlying soil since 2006 is a prerequisite for the interpretation of speleothem data from the cave in terms of climate variability the results show that bunker cave is a homogeneously ventilated cave with rather low pco2 values of 580 1200 ppmv which lacks strong seasonal variations the 18o value of cave drip water reflects the mean annual composition of the rain water and the seasonal variability is strongly attenuated indicating a well mixed karst aquifer hence stalagmites from bunker cave should be well suited to record interannual decadal climate trends seven drip sites in two cave chambers show three different types of discharge behaviour including slow seasonal drip fast seasonal drip and seepage flow the drip rate patterns of most drip sites are consistent with the main infiltration events taking into account a delay of several months an instantaneous response to precipitation i e piston flow is not observed for any drip site indicating a specific water capacity threshold in the soil karst aquifer prior calcite precipitation pcp was also identified especially during times of low discharge though pcp is not as pronounced at bunker cave as in other caves it probably has an influence on the mg ca ratios of the stalagmites

transmission of δ13c signals and its paleoclimatic implications in liangfeng cave system of guizhou province sw china a series of samples including vegetation soil organic matter soil waters spring bedrock pool water drip waters upper drip waters and ground drip waters and their corresponding speleothems were collected at liangfeng cave lfc system of guizhou province southwest of china respectively from 2003 to 2004 year then their stable carbon isotopes were measured and analyzed results reveal that vegetation is c3 type in lfc system cave overlying 13c signals including values and variations could be transmitted to drip water speleothem speleothem 13c mainly shows a biogenic 13c value character soil co2 from plant respiration and decay and there are remarkable seasonal variations of 13c values for drip water tdic speleothem which are lighter at least 2 0 in the rainy seasons than in the dry ones so it could be feasible to reconstruct high resolution changes of paleoecology and paleoclimate by using speleothem 13c values

analysis of the time averaged properties of sediment motion in a local scour process 1 we examined the kinematics of sediment particles in the proximity of a vertical plate attached to the side wall of a pressurized duct the laboratory phenomenon investigated was archetypal of local scour near bridge abutments in covered rivers we conducted a clear water scour experiment where we measured the temporal evolution of the local erosion depth the latter was found to follow a logarithmic trend the concentration and velocity of the moving particles were measured on the basis of digital movies taken at various evolution stages of the process the spatial pattern of the sediment motion showed that the action of the principal vortex system becomes progressively more evident with the general lowering of the sediment transport intensity detected as the scour hole increases in time furthermore the phenomenology of local sediment transport was analyzed key findings of the research include 1 the time averaged values of the sediment transport rate are linked with those of concentration and velocity through relationships which are almost invariant regardless of the experimental time and of the location within the scour hole 2 intermittency and irregularity of the sediment fluxes increase as their mean intensity decreases 3 the relative weight of the temporal fluctuations of concentration and velocity in the time mean sediment transport activity is significant throughout the entire process potential implications of the present results for the modeling of local scour processes in pressurized flow conditions are discussed the considerations made are likely to have analogous applicability to local scour with a free surface since the large scale evolutions of the erosion depth in the two conditions may not be greatly different given the qualitative analogy of the present findings with earlier ones obtained for one dimensional bed load it is suggested that similar considerations may hold also for the small scale modeling of a wider class of sediment transport processes

source and dispersal of jokulhlaup sediments discharged to the sea following the 1996 vatnajokull eruption the october 1996 gjalp eruption beneath vatnajokull glacier led to one of the largest jokulhlaups glacial floods in iceland in the twentieth century a catastrophic discharge of meltwater and sediment swept across the skeidararsandur flood plain to the sea tephra from the eruption consists of vesicular sideromelane shards with a basaltic andesite composition 53 sio 2 3 mgo 0 8 k 2 o after the flood sediment samples were collected from the flood plain and off the southeast coast of iceland where a major sediment plume had been created by the discharge compositions of glass shards from flood plain and seafloor deposits do not match those of the gjalp magma flood plain samples consist primarily of blocky to poorly vesicular sideromelane clasts with compositions that are characteristic of grimsvotn volcanic products 50 sio 2 5 5 mgo 0 4 k 2 o marine samples collected near the jokulhlaup outflow into the sea also consist primarily of blocky to poorly vesicular sideromelane clasts with compositions that are for the most part similar to products of the grimsvotn volcanic center distal marine samples have more vesicular sideromelane clasts with compositions that are similar to products of the katla volcanic center e g 48 sio 2 4 5 mgo 0 8 k 2 o significant deposition to the seafloor was apparently limited to an area just offshore of the skeidararsandur there is no indication that juvenile volcanic material from the gjalp eruption was carried by the 1996 jokulhlaup onto the flood plain or into the ocean instead the jokulhlaup carried primarily older volcaniclastic material eroded by the flood

explosive energy during volcanic eruptions from fractal analysis of pyroclasts abstract despite recent advances by means of experiments and high resolution surveys and the growing understanding of the physical processes before and during volcanic eruptions duration and type of eruptive activity still remain highly unpredictable this uncertainty hinders appropriate hazard and associated risk assessment tremendously in an effort to counter this problem experimentally generated pyroclasts have been studied by fractal statistics with the aim of evaluating possible relationships between eruption energy and fragmentation efficiency rapid decompression experiments have been performed on three differently porous sample sets of the 1990 1995 eruption of unzen volcano japan at 850 c and at initial pressure values above the respective fragmentation threshold u kueppers b scheu o spieler d b dingwell fragmentation efficiency of explosive volcanic eruptions a study of experimentally generated pyroclasts j volcanol geotherm res 153 2006 125 135 o spieler b kennedy u kueppers d b dingwell b scheu j taddeucci the fragmentation threshold of pyroclastic rocks epsl 226 2004 139 148 the size distribution of generated pyroclasts has been studied by fractal fragmentation theory and the fractal dimension of fragmentation df a value quantifying the intensity of fragmentation has been measured for each sample results show that size distribution of pyroclastic fragments follows a fractal law i e power law in the investigated range of fragment sizes indicating that fragmentation of experimental samples reflects a scale invariant mechanism in addition df is correlated positively with the potential energy for fragmentation pef while showing a strong influence of the open porosity of the samples results obtained in this work indicate that fractal fragmentation theory may allow for quantifying fragmentation processes during explosive volcanic eruptions by calculating the fractal dimension of the size distribution of pyroclasts it emerges from this study that fractal dimension may be utilised as a proxy for estimating the explosivity of volcanic eruptions by analysing their natural pyroclastic deposits

low temperature effects on flow in sand bed streams laboratory experiments were performed in a 40ft long 2ft wide 1ft deep 12 m 0 6 m 0 3 m tilting flume to elucidate the effects of temperature variations on the flow and sedimenttransport charac

oxygen isotopic fractionation between drip water and speleothem calcite a 10 year monitoring study central texas usa abstract speleothem 18o values can serve as a paleoclimate proxy yielding information about past temperature and rainfall an accurate determination of the equilibrium calcite water oxygen isotopic fractionation factor and an assessment of kinetic isotopic fractionation are required for interpretation of speleothem 18o data in this study 18o values were measured for calcite deposited on artificial substrates at four sites in two central texas caves monitored for over 10 years the results are used to evaluate the equilibrium isotopic fractionation factor and the impact of climatic and hydrologic conditions on kinetic isotopic fractionation the 18o values of calcite from the four sites ranged from 24 8 to 26 7 v smow and associated drip water values ranged from 4 6 to 3 9 a comparison of predicted equilibrium calcite 18o values calculated using a commonly used isotopic fractionation factor with measured values indicates that 94 of the calcite samples are not in oxygen isotopic equilibrium with respect to their associated drip water the departure from oxygen isotopic equilibrium expressed as 18occ e ranges from 0 7 to 1 4 three of the four drip sites yield similar linear relationships between 18occ e and water temperature tw and can be collectively expressed as 18occ e 0 3tw 4 7 r2 0 56 n 93 therefore calcite deposited during time periods of lower tw lower cave air co2 concentration and faster calcite deposition rates have 18o values closer to equilibrium this contradicts conceptual models which predict that a faster calcite deposition rate leads to a larger departure of calcite 18o from equilibrium if slower calcite deposition indeed facilitates equilibrium fractionation i e 18occ e 0 then the results of this study support a larger than commonly accepted value for the equilibrium calcite water oxygen isotopic fractionation factor adopting a larger published value for the fractionation factor yields negative 18occ e values of up to 2 4 these negative values cannot be explained by existing kinetic fractionation models alternatively they may reflect the trapping of a calcite surface layer with a lower 18o value than that of calcite in isotopic equilibrium with ambient water the relationship between deposition rates and 18occ e for this study is consistent with the same relationship using data for synthetic calcite from the literature this relationship indicates a 0 8 shift of calcite 18o for every ten fold increase in deposition rate at 5 to 25 c and a ph of 8 3 the significant kinetic fractionation observed in this study warrant consideration in applying measured speleothem calcite 18o values to interpret past climate conditions

speleothem isotopic evidence of winter rainfall variability in northeast turkey between 77 and 6 ka an oxygen isotope record from a stalagmite that grew between 77 ka and 6 ka in northeast turkey contains both a strong precessional signal and sub orbital oscillations similar to those in greenland ice cores and chinese speleothem records of monsoon intensity fluid inclusion evidence of a negative shift in the isotopic composition of dripwater during the lateglacial supports interpretation of the isotope curve as an insolation forced record of changes in rainfall seasonality the high amplitude millennial scale fluctuations are caused by rapid changes in rainfall seasonality and or switching of moisture source areas both of which are associated with the stadial interstadial climatic oscillations linked to the changing modes of the north atlantic meridional overturning circulation moc winter rainfall maxima in northeast turkey coincide with interstadial conditions in greenland and with periods of intensified asian monsoon activity the isotopic shifts in the record are in antiphase with and are generally much larger in amplitude than published data from stalagmites in northwest turkey most likely because of differing moisture source areas carbon isotope ratios are probably kinetically enriched by partial degassing of seepage water in the epikarst but although often difficult to decypher particularly during marine isotope stage mis 2 broadly support the interpretations of the oxygen data

mean and turbulent flow fields in a simulated ice covered channel with a gravel bed some laboratory observations northern rivers experience freeze up over the winter creating asymmetric under ice flows field and laboratory measurements of under ice flows typically exhibit flow asymmetry and its characteristics depend on the presence of roughness elements on the ice cover underside in this study flume experiments of flows under a simulated ice cover are presented open water conditions and simulated rough ice covered flows are discussed mean flow and turbulent flow statistics were obtained from an acoustic doppler velocimeter adv above a gravel bed surface a central region of faster flow develops in the middle portion of the flow with the addition of a rough cover the turbulent flow characteristics are unambiguously different when simulated ice covered conditions are used two distinct boundary layers near the bed and in the vicinity of the ice cover near the water surface are clearly identified each being characterized by high turbulent intensity levels detailed profile measurements of reynolds stresses and turbulent kinetic energy indicate that the turbulence structure is strongly influenced by the presence of an ice cover and its roughness characteristics in general for y d 0 4 where y is height above bed and d is local flow depth the addition of cover and its roughening tends to generate higher turbulent kinetic energy values in comparison to open water flows and reynolds stresses become increasingly negative due to increased turbulence levels in the vicinity of the rough ice cover the high negative reynolds stresses not only indicate high turbulence levels created by the rough ice cover but also coherent flow structures where quadrants one and three dominate copyright 2012 john wiley sons ltd

the 17 july 1999 block and ash flow baf at colima volcano new insights on volcanic granular flows from textural analysis abstract on july 17 1999 a strong explosion occurred at colima volcano mexico that produced a 10 km high eruptive column the partial column collapse originated a block and ash flow baf that flowed to the south along the san antonio and montegrande ravines travelling 3 3 km from the volcano summit the flow filled the ravines with a volume estimated at 7 9 105 m3 the erosion of these deposits occurred between 1999 and 2002 time of sampling providing excellent longitudinal outcrops that allowed their detailed textural study the study was carried out by means of quantitative textural analysis 1 rosiwal intersections for carrying out vertical granulometric profiles 2 total grain size analysis from 11 to 9 and 3 fourier and fractal analysis of the particle morphology grain size and morphometric parameters obtained with these methods were used to identify vertical and longitudinal variation patterns in the baf deposit the grain size variations allowed to infer the main particle segregation mechanisms that acted during transport and deposition of the studied bafs the two methods used for studying the particle shape morphologies yielded results with different accuracy and reliability in particular fractal analyses have been found to be the most effective in describing the particle support mechanisms that acted during transport and deposition of the studied bafs the results highlight the importance of the information obtained by means of these techniques and provide new insights in transportation and deposition mechanisms of bafs

sediment transport part iii bed forms and alluvial roughness a method is presented that makes the classification of bed forms the prediction of the bed form dimensions and the effective hydraulic roughness of the bed forms feasible the proposed relationships are based on the analysis of reliable flume and field data a verification analysis using about 1 500 alternative reliable flume and field data shows good results in predicting the hydraulic roughness friction factor for field conditions the proposed method yields considerably better results than previously proposed methods which are reviewed here the proposed method has also been used to predict the flow depth and the total bed material load

seasonal resolution of eastern mediterranean climate change since 34 ka from a soreq cave speleothem the combination of ion microprobe analysis of d 18 o and confocal laser fluorescent microscope imaging of annual growth bands in a soreq cave speleothem provides sub annual scale climate information between 34 and 4 ka this high resolution methodology is ideal both for comparing seasonal climate patterns across broad windows of time and examining rapid climate events such as the younger dryas termination in detail the sub annual d 18 o gradients we report represent a combination of seasonal variability in rainfall amount and air temperature a distinct change in both the pattern of fluorescent banding and the gradient of d 18 o measured in situ across single annual growth bands indicates a change in seasonal climate patterns of the eastern mediterranean region following heinrich event 1 and again after the younger dryas throughout the holocene wet winters and dry summers characterized regional climate during the younger dryas we find that regional climate may have been more arid than in the holocene but the fluorescent banding pattern indicates that the supply of dripwater to the cave was more consistent year round we suggest that a reduced gradient of seasonal precipitation occasional snowfall and vegetation differences may have all contributed to the isotope and fluorescent banding patterns observed during heinrich event 1 and the last glacial stadial detailed investigation of the younger dryas termination reveals a rapid onset of regional environmental change fluorescent band counting indicates that the younger dryas termination as recorded by rainfall in the

eifel maars quantitative shape characterization of juvenile ash particles eifel volcanic field germany abstract the eifel region in western central germany is the type locality for maar volcanism which is classically interpreted to be the result of explosive eruptions due to shallow interaction between magma and external water i e phreatomagmatic eruptions sedimentary structures deposit features and particle morphology found in many maar deposits of the west eifel volcanic field wevf in contrast to deposits in the east eifel volcanic field eevf lack the diagnostic criteria of typical phreatomagmatic deposits the aim of this study was to determine quantitatively the shape of wevf and eevf maar ash particles in order to infer the governing eruption style in eifel maar volcanoes the quantitative shape characterization was done by analyzing fractal dimensions of particle contours 125 250 m sieve fraction obtained from scanning electron microscopy sem and sem micro computed tomography sem micro ct images the fractal analysis dilation method and the fractal spectrum technique confirmed that the wevf and eevf maar particles have contrasting multifractal shapes whereas the low small scale dimensions of eevf particles eppelsberg green unit coincide with previously published values for phreatomagmatic particles the wevf particles meerfelder maar pulvermaar and ulmener maar have larger values indicating more complex small scale features which are characteristic for magmatic particles these quantitative results are strengthening the qualitative microscopic observations that the studied wevf maar eruptions are rather dominated by magmatic processes the different eruption styles in the two volcanic fields can be explained by the different geological and hydrological settings found in both regions and the different chemical compositions of the magmas

regional climate variability and ecosystem responses to the last deglaciation in the northern hemisphere from stable isotope data and calcite fabrics in two northern adriatic stalagmites abstract geochemical and physical changes along the growth axis of speleothems are controlled by climate as well as the dynamics of the host karst system discriminating between the two is one of the major challenges in assembling robust cave palaeoclimate records overcoming this dilemma may be achieved by investigating multiple properties from two or more speleothems from the same cave spanning the same time interval in this study we use high resolution stable oxygen and carbon isotope 13c and 18o morphological and petrographic data from two calcite stalagmites sv1 and sv7 from grotta savi italy to help constraining the regional climate conditions during the younger dryas the new sv1 record spanning 15 3 9 4 ka builds on a previously published low resolution stable isotope time series it is anchored by 22 new u th ages and lamina counting yielding a refined age model that supersedes the previous one the sv7 record is anchored by 8 u th ages and spans 13 1 10 5 ka partially overlapping the sv1 record together the morphological and geochemical characteristics of sv1 and sv7 allow us to identify site specific processes driving the isotopic variations this enables us to explore the degree of complacency in speleothems whereby periodically a speleothem is insensitive to recording a climate signal due to aquifer hydrology and network evolution the model suggests that 18o is a proxy for the infiltration amount that reaches the site of deposition which in the case of sv7 was buffered by the aquifer hydrology the interpretation of 13c in both stalagmites is more complex being influenced by both temperature and hydrology only a comparison of the two stalagmite records allows us to recognise a decoupling between the effects of hydrology and temperature according to our interpretation the most distinctive climate information of the younger dryas was the high hydrological variability with phases dominated by seasonal infiltration within an overall cooling trend our record also reveals a significant early holocene climate anomaly centred at 10 4 ka whose magnitude was possibly amplified by local synoptic conditions our research demonstrates the importance of investigating several complementary proxies particularly from morphologically diverse stalagmites when monitoring data are not available fabric and lamina thickness can be fundamental to unravelling the dominant control of hydrology or temperature on stable isotopes

magma water interactions in subaqueous and emergent basaltic in the subaqueous growth and emergence of a basaltic volcano clasts are formed by one or a combination of 1 explosive release of magmatic volatiles 2 explosive expansion and collapse of steam formed at magma water contact surfaces 3 explosive expansion of steam following enclosure of water in magma or entrapment of water close to magma and 4 cooling contraction these processes named respectivelymagmatic explosivity contact surface steam explosivity bulk interaction steam explosivity andcooling contraction granulation can be enhanced by mutual interaction and feedback the first three explosive processes are limited at certain water depths hydrostatic pressures and become increasingly vigorous at shallower levels the depth of onset of magmatic explosivity depends largely on juvenile volatile content it is up to 200 m for tholeiitic magmas and up to 1 km for alkalic magmas at the depth where formation of clastic deposits becomes predominant over effusion of lavas magmatic explosivity is subordinate to steam explosivity as a clast forming process the upward transition to accumulation of dominantly clastic deposits is not simply related to the onset of substantial exsolution of magmatic volatiles and can occur without it contact surface explosivity commonly requires initiation by a vigorous impact between magma and water and although no certain depth limit is known likelihood of such explosivity decreases rapidly with depth clast generation by bulk interaction explosivity appears to be restricted to depths much shallower than that of the critical pressure of water which in sea water is at about 3 km cooling contraction granulation can occur in any depth of water but at shallow levels may be replaced by contact surface explosivity during continuous eruption under water tephra can be ejected and deposited within a cupola of steam such that rapid quenching does not occur emergent volcanoes are characterized by distinctive steam explosive activity that results primarily from a bulk interaction between rapidly ascending magma and a highly mobile slurry of clastic material water and steam the water gets into the vent by flooding across or through the top of the tephra pile and violent explosions cease when this access is sealed the eruptions during emergence of surtsey and capelinhos typify the distinctive explosive activity the style and controls of which are different from those of maar volcanoes

textural variation in juvenile pyroclasts from an emergent surtseyan type volcanic eruption the capelas tuff cone sao miguel azores abstract here i present textural data i e vesicularity vesicle size distributions vsd plagioclase crystallinity crystal size distributions csd combined with fractal analyses of particle outlines from a natural succession of alternating fall and surge deposits in the emergent capelas tuff cone azores the textural variation in the capelas succession is surprisingly small considering the wide variety of fragmentation processes vent activity and emplacement mechanisms that are characteristic of emergent eruptions the plagioclase crystal content varies between 24 and 33 vol csd analyses of plagioclase show near linear trends with a slight increase in time for the smallest crystal sizes with surge deposits having more groundmass plagioclase when compared with fall deposits this is consistent with crystallization induced by degassing and decompression at lower eruption rates the vesicularities of the capelas pyroclasts are more variable 18 to 59 vol with vsds displaying kinked trends characteristic of coalescence this is especially evident in the fall deposits and consistent with being formed in continuous uprush jetting with an overall shallow fragmentation level within the conduit bubble coalescence can also be identified in the surge deposits although to a much lesser extent the amount of bubble coalescence is negatively correlated with the amount of groundmass crystallization i e plagioclase in the capelas deposits a relatively broad range of fractal dimensions with average dbox 1 744 and 0 032 for the outlines of pyroclastic fragments emplaced by fall or as surges indicate that there is little difference in the fragmentation process itself at capelas in addition to this the fact that the fractal dimensions for both the fall and surge end members completely overlap suggests that shape modification due to abrasion and chipping of grain edges was minor during emplacement of base surges these results are consistent with emergent eruptions building tuff cones to be a relatively low energy phreatomagmatic landform e g at least when compared with more energetic phreatomagmatic eruptions producing tuff rings and maar volcanoes

a comparison of fourier and fractal techniques in the analysis of closed forms abstract forty one samples of quartz sand grains derived from four different sources are analyzed using fourier grain shape and multi component fractal techniques the results from the two techniques are sufficiently similar to demonstrate clearly the potential usefulness of the fractal based technique in the analysis of sedimentary particles additionally the fact that the fractal technique is shown to extract information from shapes suitable for analysis via a radius expansion method lends credence to the expectation that it will yield comparable information when applied to more complex shapes not amenable to the radius expansion fourier technique

volcanic ash generation effects of componentry particle size and conduit geometry on size reduction processes abstract grain size distributions gsd of pyroclastic materials are the product of processes ranging from primary fragmentation efficiency to tephra transport as such a detailed description of their physical and chemical state can provide pivotal information regarding such processes by constraining the gsd of volcanic deposits one can thereby deliver powerful constraints on the energetics and dynamics of eruptions in order to do so we must distinguish between two primary controls 1 fragmentation of magma to tephra and 2 secondary transport related processes such as abrasion and comminution within the conduit and until deposition of the particles variations in particle interactions in the conduit together with conduit geometry may be major factors in modifying the gsd as in all physicochemical processes for eruptive dynamics an experimental basis is an essential element of calibration and quantification here we have conducted the first experimental investigation linking fragmentation and ash production via the influence of 1 particle componentry and particle size and 2 the conduit geometry constricted versus unconstricted on the gsd rapid decompression experiments with loose tephra material from the fall deposit of pomici principali eruption 10 3 ka campi flegrei have been conducted in an optically transparent setup that enables the optical monitoring of particle dynamics with a high speed camera the samples employed can be classified into two main groups 1 pumices and 2 dense clasts including crystals lava clasts and wall rock fragments our results indicate that 1 a conduit diameter constriction simulating obstacles in the conduit walls is likely to reduce the average diameter of individual clasts and increase the generation of ash

dynamic ice formation in channels as a driver for stream aquifer interactions 1 this research introduces and provides evidence of a novel mechanism of stream aquifer exchange caused by dynamic ice formation on streams at a stream site in southwestern wisconsin we document a significant fluctuation in stream depth and the potentiometric surface in the adjacent aquifer during periods of ice formation suggesting that stream aquifer interactions may be influenced by these transient events four years of winter stream data document that dynamic ice formation 1 causes an average increase in stream depth of 106 2 affects stream depth on 20 of days from december through february and 3 substantially alters stream aquifer interactions by reducing the hydraulic gradient toward the channel during ice formation events dynamic ice formation represents a potentially widespread mechanism for altering stream aquifer interactions and associated biogeochemical transformations the sensitivity of this process to air temperature indicates a need for further research on the impacts of climate warming

modelling the δ18o value of cave drip water and speleothem calcite abstract stable isotope signals recorded in speleothems have provided important insights about past climate variability in recent years quantitative reconstruction of mean annual temperature and the amount of precipitation however remains difficult because the stable isotope signals are influenced by various processes here we present a drip water model which shows how these climate parameters affect the oxygen isotope signal of cave drip water in the model the dependence of the 18 o value of drip water on mean annual temperature is established by correlation to the amount of winter precipitation and winter temperature application of the model to two caves in western germany reveals a strong influence of winter rainfall on the oxygen isotope composition of cave drip water in this region assuming equilibrium isotope fractionation between drip water and calcite we provide a function relating the 18 o value of speleothem calcite to mean annual surface temperature this function shows a clear anticorrelation between temperature and the 18 o value of speleothem calcite which has been previously reported for several caves in central and northern europe by inverse application of this function we tentatively reconstruct average temperatures for the period between 6 and 1 5 ka from the 18 o signals of two stalagmites from atta and bunker cave western germany the resulting temperature curves are very sensitive to the value used for the correlation between the amount of winter precipitation and winter temperature since this correlation was probably not constant in the past the reconstructed temperature curves are associated with substantial uncertainty

quantifying the effect of rheology on lava flow margins using fractal geometry this study aims at quantifying the effect of rheology on plan view shapes of lava flows using fractal geometry plan view shapes of lava flows are important because they reflect the processes governing flow emplacement and may provide insight into lava flow rheology and dynamics in our earlier investigation bruno et al 1992 we reported that flow margins of basalts are fractal having a characteristic shape regardless of scale we also found we could use fractal dimension d a parameter which quantifies flow margin convolution to distinguish between the two endmember types of basalts a a d 1 05 1 09 and pahoehoe d 1 13 1 23 in this work we confirm those earlier results for basalts based on a larger database and over a wider range of scale 0 125 m 2 4 km additionally we analyze ten silicic flows sio2 52 74 over a similar scale range 10 m 4 5 km we note that silicic flows tend to exhibit scale dependent or non fractal behavior we attribute this breakdown of fractal behavior at increased silica contents to the suppression of small scale features in the flow margin due to the higher viscosities and yield strengths of silicic flows these results suggest we can use the fractal properties of flow margins as a remote sensing tool to distinguish flow types our evaluation of the nonlinear aspects of flow dynamics indicates a tendency toward fractal behavior for basaltic lavas whose flow is controlled by internal fluid dynamic processes for silicic flows or basaltic flows whose flow is controlled by steep slopes our evaluation indicates non fractal behavior consistent with our observations

hydrological uncertainties in the modelling of cave drip water δ18o and the implications for stalagmite palaeoclimate reconstructions abstract in this paper we review our current understanding of karst drip water hydrology emphasising the extent of non linear and non stationary process dynamics that render stalagmite palaeoclimate reconstructions using a statistical pseudo proxy approach difficult to implement we outline an approach to attribute the uncertainty that arises specifically as a consequence of variable water routing through the overlying soil epikarst and karst aquifer this is based upon the development of a monthly lumped parameter karst hydrological model which we use to demonstrate the range of modelled drip water discharges possible from a single climate input refinement of the model to include precipitation 18 o enables us to determine the theoretical range in drip water and stalagmite 18 o for three sites with contrasting climates northern temperate nw scotland monsoonal ethiopia and mediterranean gibraltar for actual climate monthly mean temperature monthly total precipitation monthly mean precipitation 18 o we compare model simulations of karst groundwater storage and drip water 18 o to demonstrate our ability to model different climate regimes realistically we also investigate the 18 o variability associated with specific karst water reservoirs that differ in their capacity and drainage mechanisms 18 o variability is then compared to stalagmite 18 o record from the three regions for the last 45 years we conclude by reviewing the implications of our hydrological model for stalagmite 18 o quaternary palaeoclimate reconstructions over different timescales and sampling resolutions

an isotopic and modelling study of flow paths and storage in quaternary calcarenite sw australia implications for speleothem paleoclimate records abstract we investigated the distinctive shallow sub surface hydrology of the southwest western australia swwa dune calcarenite using observed rainfall and rainfall 18 o soil moisture cave drip rate and dripwater 18 o over a six year period august 2005 march 2012 a lumped parameter hydrological model is developed to describe water fluxes and drip 18 o comparison of observed data and model output allow us to assess the critical non climatic karst hydrological processes that modify the precipitation 18 o signal and discuss the implications for speleothem paleoclimate records from this cave and those with a similar karst setting our findings include evidence of multiple reservoirs characterised by distinct 18 o values and recharge responses low and high flow sites dripwaters exhibit 18 o variations in wet versus dry years at low flow sites receiving diffuse seepage from the epikarst with an attenuated isotopic composition that approximates mean rainfall recharge from high magnitude rain events is stored in a secondary reservoir which is associated with high flow dripwater that is 1 lower than our monitored low flow sites 18 o one drip site is characterised by mixed flow behaviour and exhibits a non linear threshold response after the cessation of drainage from a secondary reservoir following a record dry year 2006 additionally our results yield a better understanding of the vadose zone hydrology and dripwater characteristics in quaternary age dune limestones we show that flow to our monitored sites is dominated by diffuse flow with inferred transit times of less than one year diffuse flow appears to follow vertical preferential paths through the limestone reflecting differences in permeability and deep recharge into the host rock

comparison of hyporheic exchange under covered and uncovered channels based on linked surface and groundwater flow simulations 1 hyporheic exchange is an important process upon which stream biogeochemical cycling is dependent the potential for hyporheic exchange in covered channels i e ice covered channels karst conduits fractures with permeable sediments has not yet been assessed we characterize the potential for hyporheic exchange in covered channels using linked turbulent channel flow groundwater flow simulations simulations show that hyporheic exchange occurs in covered channels which have shallower hyporheic zones and larger hyporheic fluxes than equivalent depth equivalent discharge uncovered channels we also analyzed hyporheic exchange for the case of freely floating covers with rough undersides and found that hyporheic exchange decreases with increasing cover roughness which in turn is driven by subdued bed topography a response to additional resistance due to covers the results suggest that hyporheic exchange occurs in covered channels and may be just as or perhaps more important to the ecology and biogeochemistry of these channels than to open channel streams

boundary shear stress in rectangular ice covered channels abstractthis paper develops an analytical approach to evaluate the mean boundary shear stress in rectangular ice covered channels the flow cross section was divided into an upper ice layer and a lower bed layer at the plane of zero shear stress determined analytically from an order of the boussinesq approximation involving the eddy viscosity concept together with prandtl s mixing length theory the conformal mapping procedure was used to obtain the functional relationships for the division curves within each flow layer based on the force balance in each flow subregion an analytical model for the average bed ice and side wall shear stresses was developed the two power law for describing vertical velocity profiles in asymmetric channels was adopted to determine the location of zero shear stress and its parameters determined using coupled equations for the flat bed friction factor and an empirical relationship for the bed form friction factor a comparison between the results of the present model an

application of fractal fragmentation theory to natural pyroclastic deposits insights into volcanic explosivity of the valentano scoria cone italy abstract the extent of fragmentation triggered by basaltic volcanic eruptions has been studied by analyzing the grain size distribution of natural pyroclastic deposits and applying the fractal fragmentation theory for this purpose 75 samples have been collected from individual layers along horizontal section of the well exposed valentano scoria cone italy the cone is constituted by well defined layers of fall deposits of up to 180 cm in thickness an important feature of the stratigraphic sequence is the occurrence of several intercalated layers called breccias with clasts of different characteristics angular shape low porosity and high crystallinity in respect to the normal layers results indicate that all achieved grain size distributions show fractal behavior and can be clearly correlated with a single fragmentation event namely the magmatic fragmentation during the eruption the fractal dimension of fragmentation d increases as fragmentation efficiency increases values of d are found to vary significantly along the pyroclastic sequence defining two major trends 1 a general long range increase of d during the course of the eruption and 2 a superimposed high frequency oscillating variation of fragmentation efficiency noteworthy is the fact that the highest values of d are measured for pyroclastic deposits following breccia deposits application of a conceptual model of fractal fragmentation as claimed by natural data indicates that larger values of d have to be associated with a higher probability of fragmentation thus suggesting that the d value can be used as a proxy for the fragility i e ability to fragment of samples fractal dimension of fragmentation of single layers is positively correlated with the vesicularity of clasts this indicates that the bubble content in the ascending magma prior to and at fragmentation likely was the key factor modulating the variable fragmentation efficiency observed in the studied pyroclastic sequence we hypothesize that the long range variation of d may be associated with magma fragmentation triggered by expansion of gas bubbles progressively coalescing below solid plugs during later stages of eruptive activity whereas high frequency variations of d are interpreted as due to magma fragmentation during the slug flow regime characterizing the strombolian activity of the scoria cone

response of a modern cave system to large seasonal precipitation variability abstract speleothems are capable of providing information on the response of middle and low latitude terrestrial environments to global climate change during the pleistocene and holocene multiproxy speleothem studies however have demonstrated that complex interactions can occur in cave settings between processes that are directly and indirectly related to climate change thorough and extended monitoring of modern cave environments is necessary in order to fully understand how each cave responds to these processes on seasonal and interannual timescales and how environmental signals are preserved in speleothem carbonate regular environmental monitoring began at black chasm cavern in the sierra nevada foothills california during the winter of 2006 2007 monthly measurements of cave air temperature humidity and p co 2 in black chasm demonstrate that the cave is ventilated in the winter months when cold dense surface air sinks into the cave cave drip water flow nearly ceases during the late summer and autumn increases substantially during the winter and spring and responds within hours to storm events during the height of the rainy season rainwater and drip water 18 o and 2 h are controlled by variations in surface air temperature and moisture source while rainfall source influences rainwater isotopes through individual storm events it has less influence on drip water isotopic composition due to mixing of recharge waters delivered by different rainfall events in the epikarst variations in drip water chemistry 13 c mg ca and sr ca indicate that the greatest level of calcite precipitation upflow from the drip water collection site prior calcite precipitation occurs during the autumn october november when drip rates are slow and cave air p co 2 is low the least prior calcite precipitation occurs during the summer july august when drip rates are slow but cave air p co 2 is at a maximum while p co 2 is a primary control on prior calcite precipitation during all seasons the predominant influence of drip rate variability on prior calcite precipitation is evident when considering only those seasons winter spring and autumn characterized by low cave air p co 2 thus drip rate variability and in turn rainfall amount should provide the primary control on trace element variations ultimately captured in speleothem calcite the isotopic and chemical variability observed in black chasm drip waters supports previous interpretations of speleothem paleoclimate proxy records from a nearby cave where such monitoring is not feasible observations of the modern cave environment at black chasm provide a reference point for the interpretation of stalagmite proxy records from similar seasonal mediterranean climates

climatic and environmental controls on speleothem oxygen isotope values variations in speleothem oxygen isotope values d 18 o result from a complicated interplay of environmental controls and processes in the ocean atmosphere soil zone epikarst and cave system as such the controls on speleothem d 18 o values are extremely complex an understanding of the processes that control equilibrium and kinetic fractionation of oxygen isotopes in water and carbonate species is essential for the proper interpretation of speleothem d 18 o as paleoclimate and paleoenvironmental proxies and is best complemented by study of site specific cave processes such as infiltration flow routing drip seasonality and saturation state and cave microclimate among others this review is a process based summary of the multiple controls on d 18 o in the atmosphere soil epikarst and speleothem calcite illustrated with case studies primary controls of d 18 o in the atmosphere include temperature and relative humidity through their role in the multiple isotope effects variability and modifications of water d 18 o values in the soil and epikarst zones are dominated by evaporation mixing and infiltration of source waters the isotopically effective recharge into a cave system consists of those waters that participate in precipitation of caco3 resulting in calcite deposition rates which may be biased to time periods with optimal dripwater saturation state recent modeling experimental and observational data yield insight into the significance of kinetic fractionation between dissolved carbonate phases and solid caco3 and have implications for the hendy test to assist interpretation of speleothem d 18 o time series quantitative and semi quantitative d 18 o climate calibrations are discussed with an emphasis on some of the difficulties inherent in using modern spatial and temporal isotope gradients to interpret speleothems as paleoclimate proxy records finally several case studies of globally significant speleothem paleoclimate records are discussed that show the utility of d 18 o to reconstruct past climate

regional scale climate influences on temporal variations of rainwater and cave dripwater oxygen isotopes in northern borneo this study investigates the relationship between large scale climate variability rainfall oxygen isotopic composition 18 o and cave dripwater 18 o at gunung mulu and gunung buda national parks in northern borneo 4 n 115 e on intraseasonal to interannual timescales a 3 yr timeseries of rainfall 18 o contains prominent seasonal and interannual variability the seasonal cycle in rainfall 18 o is defined by lighter values of 10 during late boreal summer and heavier values of 4 during late boreal winter and is poorly correlated to local precipitation which displays very weak seasonality seasonally varying moisture trajectories likely play a key role in the observed seasonal cycle of rainfall 18 o driving enhanced fractionation during boreal summer and less fractionation during boreal winter dripwater 18 o timeseries display 2 seasonal cycles that follow the rainfall 18 o seasonal cycles with a mean 18 o value equivalent to the mean 18 o of rainfall large surveys of cave dripwaters conducted during three fieldtrips to gunung mulu buda reveal a system wide response to rainfall 18 o seasonality that supports a relatively short less than 6months response time for most drips during the weak 2005 2006 la nina event sustained positive precipitation anomalies are associated with rainfall 18 o values that are 4 to 5 lighter than previous years values consistent with the tropical amount effect observed in both models and data dripwater 18 o values are 1 to 2 lighter during the weak la nina event the importance of the amount effect in driving intraseasonal rainfall 18 o anomalies at our site is supported by an 8 increase in rainfall 18 o that occurred over the course of two weeks in response to a pronounced decrease in regional convective activity dripwater discharge rates underwent a ten fold decrease during the extended dry period but dripwater 18 o values remained constant this study supports the interpretation of stalagmite 18 o records from gunung mulu buda as paleo precipitation records that are sensitive to the location and strength of deep convection in the west pacific warm pool 2007 elsevier b v all rights reserved

fractal analysis applied to characteristic segments of the san andreas fault fractal theory is applied in a quantitative analysis of the san andreas fault saf geometry the method which directly measures the increase in total fault length with a decrease in ruler size gives the fractal dimension d and scaling properties for the chosen length band 0 5 1000 km a physical interpretation of d is that it measures the irregularity of the fault trace in the selected band the fault is subdivided into six segments of distinctive seismic behavior a main fault trace which shows either maximum coseismic slip or creeping was selected for analysis with three alternative branches examined for the saf system south of san bernardino branches of the fault trace are not considered in this work fractal dimensions calculated for the different segments range from 1 0008 to 1 0191 and are different from 1 0 to the 95 confidence interval these small changes reflect the overall smoothness of the main fault trace significant variations in d among segments indicate heterogeneities in the fault smoothness along strike d also changes significantly from the short length band to the long length band where the demarcation point ranges from 1 to 2 km the short length band has larger d values a slight correlation is obtained between the fractal dimension of the main trace and the extent of subparallel faulting this indicates some correspondence between the main fault trace irregularity and the complexity of subsidiary fault traces in plan view

timing duration and transitions of the last interglacial asian monsoon thorium 230 ages and oxygen isotope ratios of stalagmites from dongge cave china characterize the asian monsoon and low latitude precipitation over the past 160 000 years numerous abrupt changes in 18o 16o values result from changes in tropical and subtropical precipitation driven by insolation and millennial scale circulation shifts the last interglacial monsoon lasted 9 7 1 1 thousand years beginning with an abrupt less than 200 years drop in 18o 16o values 129 3 0 9 thousand years ago and ending with an abrupt less than 300 years rise in 18o 16o values 119 6 0 6 thousand years ago the start coincides with insolation rise and measures of full interglacial conditions indicating that insolation triggered the final rise to full interglacial conditions

monitoring of selected caves as a prerequisite for the speleothem based reconstruction of the quaternary environment in croatia abstract quaternary palaeo environmental changes that have taken place in croatia are likely to be recorded in speleothems secondary carbonate deposits precipitated in caves confident interpretation of well dated speleothem proxy records relies on modern monitoring programs which we provided in three regionally different caves parallel monitoring of the surface and cave air temperature and relative humidity precipitation and cave drip intensity as well as stable isotope modification of meteoric and drip water was carried out in order to estimate the most reliable stalagmites for the interpretation of quaternary landscape history in all three caves nova grgosova 239 m a s l t cave 11 2 c in central croatia lokvarka 780 m a s l t cave 7 5 c in the mountainous part of croatia and modric 32 m a s l t cave 16 6 c in coastal croatia we selected the parts of the caves where the ambient cave conditions appeared to be appropriate for equilibrium deposition of calcite in terms of constant air temperature seasonal amplitudes of 0 73 0 38 and 0 45 c respectively and relative humidity 100 both atlantic and mediterranean moisture influences were detected in all three caves but of different intensities cave hydrological settings governed by karst aquifer properties were resolved by the comparison of the precipitation intensities and drip site responses to the rain events and generally seasonal rainwater isotopic signal was almost completely attenuated except for one drip site such homogenized drip water and stable cave environmental settings give confidence for calcite deposition under equilibrium conditions especially for modric and nova grgosova caves where speleothems inner structures also look promising for potentially quality dating results and stable isotopic profiles the fracture flow drip regime of selected drip sites in lokvarka cave and uncompleted homogenization of the water in the epikarst might point to speleothem samples that are unsuitable for resolving multi annual quaternary climate changes this view is supported by the high porosity internal structure of some lokvarka speleothems so further monitoring sampling and the thorough speleothem examination is therefore necessary for adequate interpretations of palaeo environmental changes

stable isotope study of cave percolation waters in subtropical brazil implications for paleoclimate inferences from speleothems we analyze the interannual monthly variability of oxygen isotope ratios in data from iaea stations along the atlantic coast of south america between 238 and 348 s to evaluate the influence of parameters such as temperature rainfall amount and moisture source contribution on meteoric water recharging two karst systems in subtropical brazil in addition a 2 year monitoring program performed on soil and cave drip and rimstone pool waters from sampling sites with contrasting discharge values and located at 100 and 300 m below the surface in the santana cave system 24831v s 48843v w is used to test the influence of hydrologic and geologic features on the temporal variations of seepage water d 18 o interannual monthly variations in d 18 o of rainfall reflect primarily regional changes in moisture source contribution related to seasonal shifts in atmospheric circulation from a more monsoonal regime in summer negative values of d 18 o to a more extratropical regime in winter positive values of d 18 o variations in groundwater d 18 o indicate that the climatic signal of recent rainfall events is rapidly transmitted through the relatively deep karst aquifer to the cave drip waters regardless of location of collection in the cave in addition the data also suggest that water replenishment in the system is triggered by the increase in hydraulic head during periods when recharge exceeds the storage capacity of the soil and epikarst reservoirs significant perturbations in the groundwater composition characterized by more positive values of d 18 o are probably connected to an increased atlantic moisture contribution associated with extratropical precipitation this implies that the d 18 o of speleothems from caves in this region may be a suitable proxy for studying

image processing analysis in reconstructing fragmentation and transportation mechanisms of pyroclastic deposits the case of monte pilato rocche rosse eruptions lipari aeolian islands italy abstract a quantitative study of particle morphology of samples from monte pilato rocche rosse deposits lipari aeolian islands italy shows a significant variability in particle structure and texture the study consisted of image processing techniques and multivariate statistical methods in analysis of the quantitative particle morphology data with the goal of identifying the genetic processes responsible for the formation of the deposits from these investigations we numerically define the form of the clasts thus avoiding subjectivity in the classification of clast morphology starting from this clast definition we then construct diagrams in which clasts due to different genetic processes i e magmatic vs hydromagmatic fragmentation are discriminated based on simple nondimensional parameters the application of the methods used seems to be of general interest in discriminating the fragmentation and transportation dynamics responsible for the formation of pyroclastic deposits