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

corroborated rainfall records from aragonitic stalagmites abstract sr and ba levels of two proximal aragonite speleothems from cold air cave south africa are examined at m resolution a compositional map derived from parallel secondary ion mass spectrometry linescans indicates heterogeneity perpendicular to the stalagmite growth axis precluding the use of single linescans as a climatic proxy technique a 40 yr averaged trace element record for the cave produced from multiple parallel linescans on both stalagmites is compared with regional and local climatic rainfall temperature data for 1955 1996 this period includes two extensive drought episodes there is poor correlation between trace elements and annual mean temperature droughts correspond to minima in trace element ratios and peaks correspond to annual maxima in rainfall the onset and termination of droughts are notable inflexions however in detail annual rainfall magnitude does not correlate directly with trace element ratios indicating that kinetic factors notably variations in speleothem growth rate play a key role in trace element uptake by aragonite averaged long data sets constrained by chronological control have potential in the study of sub decadal precipitation patterns

trace element distribution in annual stalagmite laminae mapped by micrometer resolution x ray fluorescence implications for incorporation of environmentally significant species abstract stalagmite er78 from grotta di ernesto cave in ne italy displays clear annual lamination consistent with its shallow depth below a forest ecosystem subject to autumnal peaking of water infiltration synchrotron radiation scanning micro x ray fluorescence analyses of heavy elements at european synchrotron radiation facility beamline id22 and light elements at id21 with 1 3 m resolution has been combined with data from ion microprobe analyses to reveal chemical variability across the visible layers of these annual laminae a series of elements display a symmetrical peak centered around the thin dark layer at the top of each lamina the peak concentration is ordered y zn cu and pb p and br this hierarchy is thought to reflect the selectivity of transport of these elements possibly by organic colloids flushed from the soil zone during autumn infiltration ion microprobe analysis indicates na and f also increase as does h the latter reflecting increased microporosity sr displays a trough around the dark and thin autumn layer implying that its incorporation may be limited by competition with other elements mg and s show a different pattern of annual variation and fe displays none the trace metals br and y display peak abundance in the early 20th century which appears to reflect a period of tree felling rather than a climatic anomaly the results demonstrate the power of the high spatial resolution and low detection limits of the synchrotron technique and its ability to produce quantitative maps that allow distinction of layered structure from that of isolated particles or irregular inhomogeneities

seasonal variations in sr mg and p in modern speleothems grotta di ernesto italy sub annual variations in trace element chemistry and luminescence have recently been demonstrated from speleothems and offer the potential of high resolution palaeoclimatic proxies however no studies have yet examined microscopic trace element variations in relation to modern cave conditions in this study the spatial variations in trace element sr mg and p concentrations in speleothems a stalagmite and a soda straw stalactite from the alpine ernesto cave temperature 6 6 0 1 c in a forested catchment in ne italy have been studied using secondary ion mass spectrometry sims and compared with environmental parameters and waters in the modern cave an annual lamination exists in the stalagmite and soda straw stalactite in the form of clear calcite with narrow visible layers which are uv fluorescent and interpreted to contain soil derived humic fulvic acids washed into the cave during autumn rains microanalyses were undertaken of seven annual laminae probably deposited during the 1960s in the stalagmite and seven laminae in the 1990s for the stalactite the analysis results show that sr consistently has a trough and p a peak centred on the inclusion rich layer mg shows mainly a negative covariation with sr in laminae formed in the 1990s but a positive covariation in the stalagmite formed in 1960s the spatial scale of the main geochemical variations is the same as that of annual laminae of inclusion poor and inclusion rich couplets mass balance arguments are used to show that the p is inorganic in form and presumably occurs as individual phosphate ions within the calcite most drip waters show limited chemical variations but a summer peak in trace elements in 1995 and a decrease in mg ca in the following winter are notable more pronounced covariations in mg ca and sr ca are shown by a site with highly variable drip rates where ratios increase at slow drip rates the strongest seasonal variations are found in pool waters where ratios increase reflecting significant ca removal from the water into the calcite during the winter in response to seasonal pco2 variations in cave air thus the cave waters compositions tend to reflect climate conditions such that mg ca and sr ca are tentatively interpreted to be higher when climate conditions are dry combining results from the speleothems and cave water along with the behaviour of each trace species mg ca variations in the speleothems are considered to reflect their variation in the cave waters whereas sr incorporation is also dependent on precipitation rate in this case mainly controlled by temporal variations in pco2 in the cave and conceivably also by inhibitors such as phosphate p adsorption a fraction of which is subsequently incorporated within calcite depends on aqueous phosphate concentration and water flux both of which should increase during the autumn therefore multiple trace element profiles in speleothems reflect multiple aspects of environment seasonality and conditions and hence a calibration against weather records is desirable to establish their palaeoclimatological meaning the strong annual variation of trace elements and particularly p can provide chronological markers for high resolution studies of other climate proxies such as stable isotopes

sector zoning in calcite cement crystals implications for trace element distributions in carbonates abstract compositional sector zoning in calcite cement crystals from a sedimentary limestone is represented by differences of mg content of over 1300 ppm or 95 and of sr and mn contents of up to 400 ppm or roughly 50 and 80 respectively between crystallographically nonequivalent time synchronous growth sectors 10 1 1 sectors are enriched with both mg and mn relative to 10 1 4 sectors and other sectors show both greater and lesser enrichment this systematic zoning pattern requires effective distribution coefficients for these trace elements to have been different for growth on different faces differential growth rate effects for nonequivalent faces are shown to be unimportant relative to differential growth face element preferences surface crystal structure and differing coordination environments are regarded as the principal factors influencing sector related elemental partitioning differences in calcite and dolomite

annual trace element variations in a holocene speleothem high resolution secondary ionization mass spectrometry sims analysis along the growth axis of a holocene speleothem from northern scotland reveals high frequency oscillations and longer term trends in mg ca sr ca and ba ca at the scale of the high frequency oscillations mg ca and sr ca display a well defined anticorrelation while sr ca and ba ca are positively correlated imaging of elemental ratios in two dimensions reveals that the high frequency signal is well preserved and laterally continuous across the sample tims 230th ages and annual ultraviolet luminescence banding provide chronological control and demonstrate that the high frequency cyclicity is annual trace element variations in speleothem calcite are a reflection of hydrochemical processes in the unsaturated zone overlying the cave supply effects and partitioning at the water calcite interface mg partitioning between water and calcite is temperature dependent calculations suggest that the annual mg ca oscillations may be caused by seasonal temperature changes however the longer timescale variations in mg ca are too great to be explained by this mechanism seasonal variations in water residence time in the unsaturated zone which reflect effective precipitation provide a more probable explanation for the observed annual oscillations and also explain the inverse relationship between mg ca and sr ca this record suggests that trace elements in speleothems have the potential to provide the high resolution insights into interannual palaeoclimatic variability required for assessment of general circulation models

understanding the influence of slope on the threshold of coarse grain motion revisiting critical stream power abstract this paper investigates the slope dependent variation in critical mean bed shear stress for coarse grain motion and evaluates stream power per unit bed area as an alternative threshold parameter explanations for observed slope dependency and existing approaches for predicting the critical stream power per unit bed area are reviewed an analysis of secondary bed load transport datasets is used to examine the strength of associations between stream power per unit bed area mean bed shear stress and mean velocity with bed load transport rate data from an original flume study are combined with secondary data from similar flume experiments to investigate the effect of slope on both critical stream power per unit bed area and critical mean bed shear stress results suggest that stream power per unit bed area is most closely correlated with bed load transport rate and also that critical stream power per unit bed area is less variable with slope than critical mean bed shear stress alternative solutions to approximating critical stream power are explored these include 1 modifying existing expressions for critical stream power to account for higher critical mean bed shear stresses at higher slopes and 2 applying a constant dimensionless critical stream power criterion

calcite fabrics growth mechanisms and environments of formation in speleothems from the italian alps and southwestern ireland five fabrics were identified in alpine and irish caves on the basis of morphological and microstructural characteristics and re lated to growth mechanisms and growth environment columnar and fibrous fabrics grow when speleothems are continuously wet and from fluids at near equilibrium conditions low supersaturation sicc 0 35 through the screw dislocation mechanism the highly defective microcrystalline fabrics form at the same supersaturation range as co lumnar fabric but under variable discharge and the presence of growth inhibitors dendritic fabrics which have the highest density of crystal defects develop in disequilibrium conditions high supersaturation un der periodic very low flow regime periods that result in prolonged out gassing cave calcareous tufa forms in disequilibrium conditions only the calcite crystals of fabrics formed at low supersaturation seem to precipitate near isotopic equilibrium conditions

origin and palaeoenvironmental significance of lamination in stalagmites from katerloch cave austria the origin and environmental dependencies of lamination in stalagmites from katerloch common in speleothems from other cave sites are examined in detail petrographic observations and chemical analyses including isotopes of stalagmites and modern calcite were combined with multi annual cave monitoring all investigated stalagmites are composed of low mg calcite and show white porous laminae and typically thinner translucent dense laminae the binary lamination pattern results from changes in the calcite fabric white porous laminae are characterized by a high porosity and abundant fluid inclusions and also by enhanced vertical growth and thinning towards the flanks translucent dense laminae exhibit a compact fabric and constant thickness of individual growth layers u th dating supports an annual origin of the lamination and the seasonally changing intensity of cave ventilation provides a robust explanation for the observed relationships between lamination stable c isotopic compositions and trace elements mg sr and ba the seasonally variable air exchange driven by temperature contrasts between the cave interior and outside atmosphere modulates the rate and amount of co2 degassing from the drip water and affects the hydrochemistry and consequently the fabric of the precipitating calcite although cave air composition and drip rate are both major variables in controlling co2 degassing from the drip water the seasonally changing ventilation in katerloch exerts the primary control and the results suggest a secondary amplifying attenuating influence of the drip rate drip rate however might be the controlling parameter for lamina development at cave sites experiencing only small seasonal cave air exchange importantly the seasonally variable composition of drip water does not reflect the seasonal cycle of processes in the soil zone but results from exchange with the cave atmosphere the alternating porous and dense calcite fabric is the expression of a variable degree of lateral coalescence of smaller crystallites forming large columnar crystals the white porous laminae represent partial coalescence and form during the warm season low calcite 13c values are linked to low 13c values of cave air and drip water during that time this observation corresponds to times of reduced cave ventilation high pco2 of cave air low drip water ph lower calcite supersaturation and typically high drip rates in contrast the translucent dense laminae represent more or less complete lateral coalescence inclusion free during the cold season high calcite drip water and cave air 13c values i e times of enhanced cave ventilation low cave air pco2 increased drip water ph relatively high calcite supersaturation and typically low drip rates in essence the relative development of the two lamina types reflects changes in the seasonality of external air temperature and precipitation with a strong control of the winter air temperature on the intensity of cave air exchange thick translucent dense laminae are favoured by long cold and wet winters and such conditions may be related closely to the north atlantic oscillation mode weak westerlies and enhanced mediterranean cyclone activity during the cold season studies of speleothem lamination can thus help to better understand and quantify the role of seasonality changes for example during rapid climate events

late holocene annual growth in three alpine stalagmites records the influence of solar activity and the north atlantic oscillation on winter climate annual growth rates and the ratio of dark to light colored calcite within single annual laminae in three contemporaneously deposited holocene speleothems from grotta di ernesto an alpine cave in northern italy respond to changes in surface temperature rather than precipitation based on monitoring of present day calcite growth and correlation with instrumental data for surface climatic conditions we interpret a higher ratio of dark to light colored calcite and the simultaneous thinning of annual laminae as indicative of colder than present winters such dark and thin laminae occur in those parts of the three stalagmites deposited from ad 1650 to 1713 and from ad 1798 to 1840 as reconstructed through lamina counting these periods correspond to the well known maunder and dalton minima of solar activity an 11 yr cyclicity in growth rate coupled with reduced calcite deposition during the historic minima of solar activity is indicative of a solar influence on lamina thickness spectral analysis of the lamina thickness data also suggests that the north atlantic oscillation variability influenced winter temperatures based on the present day controls on cave calcite formation we infer that high frequency changes in solar activity modulated the seasonal duration of soil co2 production

regional temperature atmospheric circulation and sea ice variability within the younger dryas event constrained using a speleothem from northern iberia precisely dated high resolution stable isotope and trace element data from a stalagmite from la garma cave northern spain reveal several stages of distinct climatic variability along the northern iberian atlantic margin and provide new constraints on the latitude of north atlantic westerlies during the younger dryas event yd westerly wind position reconstructed using sub annually resolved mg data as a proxy for sea spray contributions associated with wind strength at this coastal cave site during the early yd 12 85 12 15 kyr oscillated meridionally resembling the decadal scale component of the modern north atlantic oscillation nao northward repositioning of westerly storm tracks over northern iberia began at 12 15 kyr consistent with other high resolution wind proxy reconstructions from central and northern europe but occurred more gradually nearer the atlantic margin from 12 15 kyr to the yd termination atmospheric circulation resembled a persistently positive nao with westerlies reaching their maximum northward extent at 11 8 kyr reflected by a mg concentration minimum at this time air temperature reflected by our 18o data and iberian wind strength were predominantly coupled throughout the yd suggesting that temperature modulated sea ice extent and consequently controlled westerly wind latitude however our data suggest that abrupt warming at 12 1 kyr was followed by much more gradual northward shifts in westerly position and that a lag existed between the warming and sea ice retreat this gradual return of the westerlies to the north beginning at 12 1 kyr is consistent with inferred changes in wind strength at other european sites additionally atmospheric circulation inferred from our northern iberian wind strength proxy record generally tracked low frequency meridional shifts in intertropical convergence zone position corroborating past research that suggested closely coupled low and high latitude atmospheric teleconnections over this period

variations in atmospheric sulphate recorded in stalagmites by synchrotron micro xrf and xanes analyses abstract we report here the first speleothem time series of the variability of sulphate a species whose abundance in catchments is strongly influenced by atmospheric anthropogenic and volcanic sources annually resolved archives of s mg si and p were generated by applying synchrotron radiation micro x ray fluorescence xrf to two speleothems from different sites in northern italy x ray absorption edge spectrometry proves that the s is in the form of sulphate and xrf mapping demonstrates that s is within calcite and enriched zones are predominantly as layers a post 1850 a d record from the ernesto cave shows a substantial rise in sulphate interpreted as reflecting the largely anthropogenically forced variation of sulphate of the atmospheric boundary layer moderated by some ecosystem storage analysis of the circa 5 2 to circa 5 0 ka interval of a speleothem from savi cave where ecosystem retention of s is likely to have been minimal shows a spiky sulphate record resembling that of ice cores a series of sulphate peaks suggest that multiple volcanic sulphate aerosol emissions at that time this probably enhanced summer temperature cooling thus favouring the preservation of the human mummy of neolithic copper age the iceman on the watershed between italy and austria both examples illustrate the power of speleothems to record atmospheric sulphate variability

controls on trace element sr mg compositions of carbonate cave waters implications for speleothem climatic records abstract at two caves clamouse s france and ernesto ne italy cave drip and pool waters were collected and sampled at intervals over a 2 3 year period mg ca and sr ca concentration ratios corrected for marine aerosols are compared with those of bedrocks and in some cases aqueous leachates of soils and weathered bedrocks cave waters do not lie along mixing lines between calcite and dolomite of bedrock carbonate but typically show enhanced and covarying mg ca and sr ca four factors are considered as controlling processes 1 the much faster dissolution rate of calcite than dolomite allows for the possibility of increase of mg ca if water rock contact times are increased during drier conditions a theoretical model is shown to be comparable to experimental leachates 2 prior calcite precipitation along a flow path is a powerful mechanism for generating enhanced and covarying mg ca and sr ca ratios this mechanism requires the solution to lose co 2 into pores or caverns 3 incongruent dolomite dissolution has only limited potential and is best regarded as two separate processes of dolomite dissolution and calcite precipitation 4 selective leaching of mg and sr with respect to ca is shown to be important in leachates from ernesto where it appears to be a phenomenon of calcite dissolution in general selective leaching can occur whenever ca is sequestered into precipitates due to freezing or drying of soils or if there is derivation of excess sr and mg from non carbonate species the ernesto cave has abundant water supply which in the main chamber is derived from a reservoir with year round constant p co 2 of around 10 2 4 and no evidence of calcite precipitation in the karst above the cave two distinct but overlying trends of enhanced and covarying mg ca and sr ca away from the locus of bedrock compositions are due to calcite precipitation within the cave and at a variable drip site due to enhanced selective leaching at slow drip rates mg enhancement in the first chamber is due to a more dolomitic bedrock and longer residence times the clamouse site has a less abundant water supply and presents geochemical evidence of prior calcite precipitation both in the cave and in overlying porous dolomite dedolomitized limestone bedrock initial p co 2 values as high as 10 1 are inferred experimental incubations of clamouse soils which generated enhanced p co 2 and precipitated caco 3 had compositions similar to the karst waters calcite precipitation is inferred to be enhanced in drier conditions hydrological controls on cave water chemistry imply that the trace element chemistry of speleothems may be interpretable in palaeohydrological terms drier conditions tends to promote not only longer mean residence times enhancing dolomite dissolution and hence mg ca but also enhances degassing and calcite precipitation leading to increased mg ca and sr ca

seismo ionospheric observations modeling and backprojection of the 2016 kaikōura earthquake we processed global navigation satellite system gnss time series data to extract total electron content tec perturbations of the ionosphere caused by the kaik ura earthquake we used ray based modeling to infer which part of the earth s surface coupled significant energy from the solid earth into the atmosphere we compared modeled tec data with the observed time series data and determined that significant coupling occurred north northeast of the initial slip this work corroborates existing analysis made with geodetic and interferometric synthetic aperture radar insar data the tec data suggested that the initial rupture coupled some energy into the atmosphere but later surface displacements 60 s after the initiation caused more significant ionospheric perturbations using an array of gnss stations we were able to track the moveout of the acoustic wave through the ionosphere we used a method commonly used in seismological studies called backprojection to estimate the location of the source of the tec perturbation on earth s surface this is the first time that this method has been applied to tec data and the results are promising the backprojection results are slightly shifted in space from the known area of maximum uplift and we attribute this small discrepancy to the fact that we did not account for horizontal winds in the atmosphere nor the 3d heterogeneity of the real atmosphere in the travel time modeling

comparison of high resolution sub annual records of trace elements in a modern 1911 1992 speleothem with instrumental climate data from southwest australia high spatial resolution measurements of mg p u sr ba and na using 193 nm excimer laser ablation inductively coupled plasma mass spectrometry has revealed clearly resolvable annual cycles in a modern speleothem from southwestern australia the age of this stalagmite is established by the dates of emplacement and removal of the boardwalk where it grew 1911 1992 this chronological constraint allows for the first confident comparison between the instrumental climate record and speleothem trace element content eleven laser ablation transects across a 0 5 mm wide section of the speleothem growth axis were measured cycles that could be matched between adjacent transects were stacked into a master record to minimise variability between tracks and permit greater confidence in comparing the trace elements to the instrumental climate record p and u positively and mg inversely mimic the sudden 20 decrease in annual rainfall experienced by this region since 1965 we argue that p from seasonal vegetation decay is transported to the speleothem before it is mineralised in the soil owing to the low p retention capacity of southwest australian soils both vegetation activity and the transport of vegetation derived hpo42 are sensitive to rainfall groundwater p concentration may also influence the transport of u through the strong affinity between phosphate and uranyl ions mg appears to be sensitive to groundwater residence time as this affects drip water mg ca composition by preferential loss of ca during drier episodes when calcite precipitates before reaching the stalagmite the effects of groundwater residence time may also be important for sr on inter annual scales however the behaviour of sr on the annual cycle is opposite to mg but compatible with ba and na which are shown to depend on speleothem growth rate

organic proxies in speleothems new developments advantages and limitations abstract research into organic matter in speleothems has progressed recently to encompass new analytical approaches and applications which offer increased potential in areas such as palaeo temperature reconstruction and high resolution palaeo environmental records from the quaternary here we review three major areas of relevance for future work in the field the origin transport and transformation of the organic matter which is ultimately preserved in speleothems the types of proxies currently available for use or in development and their advantages and issues and the recently developed prospect of high resolution organic matter records derived from the analysis of organic trace elements complexes the continuing extension of work in these research areas offers excellent potential for organic speleothem proxies to grow as a valuable tool in palaeoenvironmental research

structure of the 8200 year cold event revealed by a speleothem trace element record abrupt first order shifts in strontium and phosphorus concentrations in stalagmite calcite deposited in western ireland during the 8200 year event the major cooling episode 8200 years before the present are interpreted as responses to a drier climate lasting about 37 years both shifts are centered on 8330 80 years before the present coinciding with a large oxygen isotope anomaly and a change in the calcite petrography in this very high resolution monthly record antipathetic second order oscillations in phosphorus and strontium reveal decreased growth rates and increased rainfall seasonality growth rate variations within the event reveal a two pronged structure consistent with recent model simulations

trace element variation in speleothem aragonite potential for palaeoenvironmental reconstruction trace element variation in annually laminated stalagmites has the potential to record long term high resolution palaeoclimatic data provided both 1 the relationship between trace element content in the carbonate and the climate and 2 the mechanism of stalagmite growth are understood here we report a secondary ion mass spectrometry sims study of an aragonitic speleothem t7 from cold air cave southern africa which achieves small m spatial resolution and ppm precision t7 has a series of fine visible laminae believed to be annual to subannual this article establishes 1 the usefulness of sims in analyzing speleothem aragonite at the spatial resolution and precision relevant to climatic studies 2 the distribution of trace elements in aragonite on micron scales and their relationship to models for speleothem growth and 3 the potential of aragonite speleothems to encode climatic data at subannual resolution complex reproducible oscillations in sr ca and ba ca are observed parallel to the growth direction of the speleothem however in addition to this variability we observe trace element oscillations perpendicular to the growth direction and infer that aragonite crystallites in the speleothem are laterally as well as vertically zoned stepscans parallel to the growth direction demonstrate complex zoning patterns from which simple climatic data are difficult to extract due to small scale lateral heterogeneity in the aragonite however time series analysis of the whole data set reveals regular cycles in sr ca and ba ca at a scale that matches the magnitude of the visible laminae on this basis it appears that within the complex geochemical variability there resides a regular environmental control possibly variation in water throughput hence rainfall

87sr 86sr and sr ca in speleothems for paleoclimate reconstruction in central china between 70 and 280 kyr ago limestone cave deposits speleothems provide archives for past changes in regional climates over a range of timescales while 18o and 13c in speleothem calcite have been commonly used for reconstruction of paleoclimates we report here further efforts in the use of 87sr 86sr and sr ca signals in speleothem calcite to deduce paleomonsoon variability near the loess plateau of central china a two end member mass balance model of concentration and isotopic composition of strontium in a cave system is used to estimate variation of the 87sr 86sr ratio in sediments overlying a limestone cave we show that this ratio reflects climate driven variations in the provenance and the extent of chemical weathering of the epikarstic sediments the measurements of 87sr 86sr made on a well dated stalagmite sfl from buddha cave 33o40n 109o05 e show ratios of 0 71092 to 0 71133 0 00001 as 2 during relatively cold periods e g marine isotope stage mis 5b 5d and 8 lower than ratios of 0 71133 to 0 71194 during relatively warm periods e g mis 5a 5c 5e and 7 as changes in the sr ca ratio may affect speleothem 87sr 86sr we show that the direct use of speleothem 87sr 86sr is less ideal than our modeled 87sr 86sr for the exogenic sr source above the cave as a paleomonsoon proxy using the 18o 13c sr ca and 87sr 86sr records of the stalagmite we reconstruct the variability of the east asian monsoon for the time period between 70 and 280 kyr ago the results show that summer monsoons were more intense during interglacial periods than during glacial periods

petrography strontium barium and uranium concentrations and strontium and uranium isotope ratios in speleothems as palaeoclimatic proxies soreq cave israel the reconstruction of the palaeoclimate of the eastern mediterranean region for the last 60 ka bp is based on the 18o and 13c variations of speleothems from soreq cave israel climatic conditions during most of the time interval between 60 and 17 ka bp the period equivalent to the last glacial were relatively cold and dry while they were warmer and wetter from 17 ka bp to the present at 17 ka bp there was a major climatic change with a sharp increase in annual rainfall and temperature and a very wet period occurring between 8 5 and 7 0 ka bp during the colder and drier period large detritus free preferentially oriented calcite crystals were deposited from slow moving water as a result of a sharp change in the hydrological regime at 17 ka bp fast moving water started entrainment of the soil and carrying detrital material into the cave and the calcite crystals deposited became small and anhedral coinciding with the petrographic and isotopic changes a sharp drop occurred in the concentration

the nature of annual lamination in carbonate flowstones from non karstic fractures vinschgau northern italy abstract the vinschgau is an inneralpine valley in the southern alps whose steep flanks are composed of strongly sheared gneisses and schists affected by deep seated gravitational slope deformations fractures generated by these movements host a groundwater system characterised by high amounts of dissolved solids which reflect long residence times and water rock interactions driven by sulphide oxidation this in combination with high air and soil temperatures on the south facing slope sonnenberg of the valley favoured the deposition of calcite and aragonite flowstone in shallow parts of this fractured non karstic aquifer about 5 of these speleothems exhibit well developed regular lamination whose annual origin was confirmed by radiometric dating a stable isotope petrographic and trace element study combined with u th dating was undertaken to disentangle the processes controlling lamina formation a succession of darker and lighter laminae forms distinct macroscopic couplets 0 2 2 mm wide in three of the samples while one sample comprises alternating white and translucent laminae microscopically the darker and white laminae show a higher abundance of opaque particles whose organic origin is confirmed by their strong epifluorescence the crystal fabric is dominated by the fascicular optic type the calcite shows regular 18 o oscillations with an amplitude of up to 1 2 with the exception of one sample 13 c lacks such a regular pattern and only shows smaller variations which do not correlate with 18 o in a consistent way all samples exhibit regular low amplitude mg sr ba and u cycles in three samples mg shows oscillations similar to the 18 o cycles in their frequency but opposite in phasing 18 o and mg oscillations are primarily attributed to surface temperature variations that are transmitted to the shallow subsurface by thermal conduction low amplitude trace element cycles mg sr ba and u are most probably driven by intra annual variations in the degree of prior aragonite precipitation in the seepage path which relates to seasonal changes in evaporation

new type of compositional zoning in calcite insights into crystal growth mechanisms compositional zoning of trace elements is observed in time equivalent regions within 10 overline 1 4 growth sectors of natural and synthetic calcite single crystals and has been called intrasectoral zoning to distinguish it from conventional sectoral zoning differential interference contrast microscopy shows that 101 overline 1 4 faces grow by the spiral mechanism cathodoluminescence microscopy and electron probe microanalyses reveal that trace element partitioning differences on 101 overline 1 4 faces correspond exactly to crystallographically controlled orientations of growth steps effective partitioning of mg and mn varies up to a factor of four between time correlative growth steps spreading in different directions effective sr partitioning varies by approximately 20 and is inversely correlated with enrichment trends of mg and mn preferential incorporation of different aqueous species at different growth steps may provide an explanation for morphological and chemical variation in natural calcites

microbes in caves agents of calcite corrosion and precipitation abstract diverse biogenic and abiogenic processes produce calcite speleothems from a biogenic perspective cave microbes mediate a wide range of destructive and constructive processes that collectively influence the growth of calcite speleothems and their internal fabrics destructive processes include substrate breakdown by dissolution boring and residue micrite production whereas constructive processes include microbe calcification trapping and binding of detrital particles to substrates and microbial induced calcite precipitation biogenesis can be established from 1 the presence of mineralized microbes 2 fabrics such as stromatolite like structures that can be attributed to microbial activity and or 3 geochemical proxies carbon and oxygen isotopes lipid biomarkers considered indicative of microbe activity such criteria have for example been used to demonstrate microbial involvement in the formation of pool fingers stalactites stalagmites cave pisoliths and moonmilk nevertheless absolute proof of microbial biogenesis in calcitic speleothems is commonly difficult because taphonomic processes and or diagenetic processes commonly mask evidence of microbial activity the assumption that calcitic speleothems are abiogenic which has been tacitly assumed in many studies is dangerous as there is clear evidence that microbes thrive in most caves and can directly and indirectly influence calcite precipitation in many different ways

multi proxy stalagmite records from northern california reveal dynamic patterns of regional hydroclimate over the last glacial cycle abstract despite its importance for california s water resources little is known about how precipitation has varied in far northern california beyond the historical record we present a new multi proxy paleoclimate record derived from two coeval stalagmites from lake shasta caverns lsc california that covers the end of marine isotope stage 3 through heinrich stadial 1 35 000 to 14 000 years bp at 40 8 n lsc is situated within the transition zone between regions in the northwestern and southwestern united states that demonstrate different precipitation responses to both modern and paleoclimatic drivers stable isotope and trace element proxies from lsc stalagmites indicate the region experienced wet conditions during interstadials warm periods associated with dansgaard oeschger cycles similar to proxy records from southern oregon and the northern great basin but in contrast to records from the desert southwest similar to the northern cascades and rocky mountains lsc was drier during the last glacial maximum however proxies indicate increased rainfall throughout heinrich stadial 1 similar to the great basin and southwest thus the lsc record demonstrates the non stationarity of the transition zone location and illustrates a complex pattern of precipitation response to global climate change in the western united states covariation of speleothem 18o an indicator of moisture source with 13c and trace elements indicators of moisture amount suggest a higher proportion of central pacific precipitation during the last glacial maximum despite the enhanced aridity in contrast periods characterized by increased precipitation amounts such as early heinrich 1 are associated with enhanced moisture from the northern pacific

annual to sub annual resolution of multiple trace element trends in speleothems this study aims to establish evidence for the widespread existence of preserved high resolution trace element variations in speleothems that may have climatic significance ion microprobe analysis of speleothems reveals that annual to sub annual variations in element chemistry exist at five shallow western european cave sites crag cave county kerry and ballynamintra county waterford ireland uamh an tartair sutherland scotland grotte pere noel belgium grotta di ernesto ne italy with widely varying climatic geomorphic and geological settings the variations are not restricted to species mg sr and ba known to substitute directly for ca in the calcite lattice but include h f na and p phosphorus as phosphate displays the greatest variability and may have the most significance as a proxy for the seasonal temperature cycle because of its role as a nutrient element the technique allows estimation of growth rate of speleothems at any interval of interest which is one of several possible uses in palaeoclimatology

complex speleothem growth processes revealed by trace element mapping and scanning electron microscopy of annual layers closely spaced transects measured by excimer laser ablation inductively coupled plasma mass spectrometry ela icpms at 5 and 32 m spatial resolution are used to generate trace element composition maps ba sr mg u na p and al from mnd s1 a previously studied modern stalagmite from southwest australia treble et al 2003 epsl216 141 rainfall at the site is highly seasonal and trace elements in mnd s1 show strong seasonal variation trace element maps show that ba sr u and na concentrations coherently follow annual growth layers identified from scanning electron microscopy sem images the sem images also reveal that stalagmite growth did not proceed uniformly growth layers vary in thickness and locally pinch out highly preferential crystal growth determined by nucleation sites left by the previous year s growth may be responsible for this uneven growth layering differential crystal growth apparently causes variability of trace element concentrations along each annual layer although additional disequilibrium processes affect mg which is less distinctly banded than ba sr u and na uneven and discontinuous growth layers influence the number of annual cycles their wavelengths and seasonal amplitudes measured in any one transect this has clear implications for studies that use annual trace element cycles as chronological markers growth rate or seasonality proxies