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

reactivated faulting near cushing oklahoma increased potential for a triggered earthquake in an area of united states strategic infrastructure in october 2014 two moderate sized earthquakes mw 4 0 and 4 3 struck south of cushing oklahoma below the largest crude oil storage facility in the world combined analysis of the spatial distribution of earthquakes and regional moment tensor focal mechanisms indicate reactivation of a subsurface unnamed and unmapped left lateral strike slip fault coulomb failure stress change calculations using the relocated seismicity and slip distribution determined from regional moment tensors allow for the possibility that the wilzetta whitetail fault zone south of cushing oklahoma could produce a large damaging earthquake comparable to the 2011 prague event resultant very strong shaking levels mmi vii in the epicentral region present the possibility of this potential earthquake causing moderate to heavy damage to national strategic infrastructure and local communities

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

chemical element imaging for speleothem geochemistry application to a uranium bearing corallite with aragonite diagenesis to opal eastern siberia russia abstract two complementary image based microanalysis methods digital autoradiography of radioactive elements and x ray fluorescence microspectroscopy micro xrf were used to study the geochemistry of a speleothem from eastern siberia our objective was to show the interest of these micro chemical methods to investigate the distribution of u and some other elements as ca sr and si in speleothems the sample studied was a corallite concretion that formed slowly by the precipitation of minerals from moisture that had condensed underground polished sections of the sample revealed alternating laminas of gray calcite and white aragonite the concretion which is older than 400 kyr u th tims showed no signs of detrital contamination 230 th 232 th 10 000 digital autoradiography and xrf analyses indicated exceptionally high uranium contents ranging from 3 10 to more than 1300 g g 1 in different areas of the sample element maps for calcium ca uranium u strontium sr and silicon si showed inverse correlations between ca and u and between ca and si but there is a strong correlation between si and u under the optical microscope the low ca appears as corrosion voids which were found to contain uranium enriched amorphous silica replacing areas of aragonite and in some cases calcite this postgenetic amorphous and uraniferous silica is composed of two kinds of opal opal a formed by large microspheres of 30 40 m in diameter and a gray opal ct with irregular lepispheres this late opal dated around 385 412 kyr is probably due to a special volcanic event formed by uraniferous glass ashes easily soluble by meteoric waters as suggested by the presence of volcanic suite in the fine fraction of the opal opal precipitated after speleothem crystallization by evaporation or cryogenic supersaturation the study of this exceptional concretion shows the value of direct chemical imaging methods as they easily revealed the presence and distribution of u in the concretion and allowed an unusual case of opal diagenesis in a carbonate speleothem to be described given the value of speleothems as geo chronometers and recorders of environmental changes at different time scales from season to isotopic stage this methodology opens new perspectives in understanding the geochemical system and consequently the validity of radiometric datings u th and u pb especially in speleothem samples

high resolution secondary ionisation mass spectrometry sims δ18o analyses of hulu cave speleothem at the time of heinrich event 1 abstract the suitability of in situ secondary ionisation mass spectrometry sims techniques for measuring o isotopes in speleothems is critically examined by applying this technique to a 500 year interval of the well known hulu cave record wang y j cheng h edwards r l an z s wu j y shen c c dorale j a 2001 a high resolution absolute dated late pleistocene monsoon record from hulu cave china science 294 2345 2348 this interval includes a large abrupt 2 shift in 18o at 16 07 ka which may correlate to heinrich event i h1 the high resolution sims method provides annual to near annual 18o data thereby increasing the temporal resolution of the previously published hulu cave isotopic data by approximately tenfold sims 18o data reveal that 75 of the abrupt isotopic shift at 16 07 ka occurred in just 1 to 2 years and the full 2 occurs over 6 years compared with an upper limit of 20 years as previously determined by conventional methods employing micro cutting acid digestion and co2 gas source mass spectrometry methods sims 18o data also reveal numerous high amplitude 1 3 high frequency

effective pressure or what is the effect of pressure using time lapse seismics as a reservoir monitoring tool geophysics can help distinguish different reservoir production scenarios for example eiken et al 2000 successfully detected fluid saturation changes after co2 injection using time lapse seismics at sleipner field over the cycle of a reservoir life oil saturation usually decreases reservoir pressure declines and gas breakout may occur these changes cause rock property changes that are detectible in time lapse seismics therefore it is important to understand the effects of pressure and saturation changes on rock properties while the effects of saturation changes are often well described by gassmann 1951 brown and korringa 1975 and mavko 1975 the effects of pressure changes are less understood here we focus on understanding the effects of fluid pressure on velocities

a three thousand year record of north atlantic climate annual band counting on three radiometrically dated stalagmites from nw scotland provides a record of growth rate variations for the last 3000 years over the period of instrumental meteorological records we have a good historical calibration with local climate mean annual temperature mean annual precipitation regional climate north atlantic oscillation and sea surface temperature sst strongest at 65 70 n 15 20 w although the correlation with the latter breaks down prior to the instrumental record this suggests that the climatic factors that force nw scottish climate and therefore our stalagmite growth varied through time and include winter nao strength the strength of the thermohaline circulation and possibly solar output spectral analysis was performed on the stalagmite growth rate time series a spectral frequency of 50 70 years is predominant in two stalagmites that were deposited from 1000 to 3000 bp a slightly longer frequency of 72 94 years is dominant from 1000 bp to present these are the same as that observed in ocean gcm output for the north atlantic region ssts our stalagmites provide high resolution precisely dated evidence of a similar periodicity predominating over the last 3000 years in a climate proxy record known to be sensitive to changes in forcing functions relevant to the north atlantic sector

a thousand year speleothem proxy record of north atlantic climate from scotland luminescent organic matter in stalagmites may form annual bands allowing growth rate to be precisely determined stalagmite growth rate is controlled by precipitation so annual bands can be used to derive long precipitation records a continuously banded stalagmite from a cave in nw scotland was used to provide a 1100 year high resolution record of precipitation the location of the cave means that precipitation is closely linked to the north atlantic oscillation for which a record is also derived this suggests that changes in the north atlantic oscillation state was an important control on european climate over the past millennium

physicochemical characteristics of drip waters influence on mineralogy and crystal morphology of recent cave carbonate precipitates speleothems are one of the most intensively explored continental archives for palaeoclimate variability the parameters however that control speleothem petrography and its changes with time and space specifically calcite crystal morphology and carbonate mineralogy are still poorly understood in order to shed light on processes and their products precipitation experiments of recent carbonate crystals on watch glasses and glass plates were performed in seven selected caves drip water sites were analysed for their fluid mg ca molar ratio ph degree of saturation for calcite and aragonite and drip rates corresponding precipitates were analysed with respect to their mineralogy calcite crystal morphology and mg ca molar ratio of calcite the following results are found high fluid mg ca ratios are found only for caves situated in dolostone thus the hostrock lithology indirectly controls the carbonate mineralogy and calcite crystal morphology of speleothems the precipitation of aragonite in place of calcite occurred only in dolostone caves and is bound to very specific conditions these are high fluid mg ca ratios 0 5 high fluid ph 8 2 and low fluid saturation indices for calcite 0 8 these specific conditions are induced by slow drip rates of 0 2 ml min as often under more arid conditions causing the precipitation of calcite aragonite prior to reaching the stalagmite top due to this fluid chemistry is altered which in turn leads to changes in carbonate mineralogy and geochemistry on the stalagmite top calcite growth is inhibited at high fluid mg ca ratios and hence aragonite precipitation is kinetically stabilised an increase of the drip water mg ca ratio leads to an increased incorporation of mg2 into the calcite crystal lattice and thus to a change in calcite crystal morphology four distinctive changes occur with increasing mg2 incorporation i development of new forms steeper rhombohedra and base pinacoid at the edges and corners of the crystal seed ii crystal habit tend to elongate along 0 0 1 due to slower growth of faces with high mg2 densities iii reconstitution of crystal faces with low mg2 densities and iv occurrence of calcite crystals with bended faces and edges due to very high mg2 mg ca ratios of 0 009 0 051 incorporation growth rates and possibly also organic compounds however may also affect the morphology of calcite crystals based on the data shown here the relation of mg2 incorporation and the resulting changes in calcite crystal morphologies as well as the conditions of aragonite precipitation are now clearly better understood further work should aim at linking the calcite crystal morphology of watch glass precipitates with calcite crystal fabrics in speleothems in order to exploit the petrographic archive of speleothem deposits

flow rate dictates permeability enhancement during fluid pressure oscillations in laboratory experiments flow rate dictates permeability enhancement during fluid pressure oscillations in laboratory experiments thibault candela 1 2 emily e brodsky 2 chris marone 1 derek elsworth 1 1 dept geosciences penn state univ university park pa united states 2 dept earth sciences uc santa cruz santa cruz ca united states

relationship between modern rainfall variability cave dripwater and stalagmite geochemistry in guam usa 1 modern rainwater cave dripwater and cave stalagmite geochemical time series from a cave in guam 13 38 n 144 53 e are used to better understand how changes in cave stalagmite geochemistry relate to aboveground changes in rainfall at a tropical location a scientific field team based in guam collects monthly samples from multiple sites for geochemical analyses at a cave and aboveground rainfall from a nearby location we compute a transfer function between rainfall amount and oxygen isotopic composition 18o of a decrease increase of 0 94 0 3 m year for every 1 increase decrease in rainfall 18o based on data extracted from the international atomic energy agency iaea global networks of isotopes in precipitation gnip database and from data generated in this study dripwater 18o and mg ca ratios show annual cyclicity at some but not all sites accentuating the complex nature of cave hydrology a stalagmite 18o record for the last 160 years indicates the existence of droughts of decadal length when rainfall is estimated to be 0 65 0 3 m year less than average conditions this estimate of rainfall reduction most likely refers to wet season months as these months preferentially contribute to groundwater recharge the proxy based climate record at guam provides new evidence highlighting how a rainy site in the western pacific warm pool today can experience considerable changes in rainfall on decadal timescales

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

phosphorus speciation in calcite speleothems determined from solid state nmr spectroscopy abstract variations in speleothem p concentration show cyclic patterns that have important implications for high resolution palaeoclimate and palaeoenvironmental reconstructions however little is known about the speciation of p in calcite speleothems here we employ solid state 31p and 1h magic angle spinning nuclear magnetic resonance mas nmr spectroscopic techniques as a non destructive method for analyzing the distribution of p in speleothems the 31p mas nmr results show three peaks indicating the presence of three primary types of phosphate species in samples from the grotta di ernesto northeastern italy a broad peak at a chemical shift p 31 3 1 to 3 7 ppm from individual phosphate ions incorporated within calcite a narrow set of peaks near p 31 0 9 ppm from crystalline monetite and a narrow peak at p 31 2 9 ppm from an unidentified crystalline phosphate phase essentially identical results were obtained for a synthetic calcite phosphate coprecipitate spectra collected for a sample from grotte de clamouse southern france show only a broad peak near 3 5 ppm suggesting a possible limit for phosphate incorporation into the calcite structure these data suggest that p in this system can interact to form calcium phosphate surface precipitates during infiltration events and are subsequently enclosed during calcite growth

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

carbonate deposits from the ancient aqueduct of beziers france a high resolution palaeoenvironmental archive for the roman empire abstract carbonate deposits from a roman aqueduct in beziers southern france record environmental conditions during the late first century c e these deposits formed in a steep section of the aqueduct with a high flow velocity which caused rapid deposition of up to 11 mm of calcite per year over a period of 22 24 years the microstructure trace element and stable isotope composition show that regular deposition was interrupted by high discharge events probably in response to heavy rainfall during autumn and winter transporting colloidally and particle bound elements and depositing calcite with elevated 18 o values individual autumn high discharge events coincide with abrupt decreases in 13 c from 8 to 12 giving rise to a saw tooth profile in some years several high flow events persisted throughout the winter suppressing this profile event horizons of micrite capping sparite growth surfaces enriched in mg may represent anomalously low water levels or periods when the channel fell dry in comparison to carbonate deposits from roman aqueducts in the eastern mediterranean visible layering is less regular and pronounced in beziers reflecting a more complex precipitation pattern

trace metal and carbon isotopic variations in cave dripwater and stalagmite geochemistry from northern borneo we investigate stalagmite trace metal ratios and carbon isotopic composition 13 c as potential paleoclimate proxies by comparing cave dripwaters stalagmites and bedrock composition from gunung mulu and gunung buda national parks in northern borneo a tropical rainforest karst site three year long biweekly time series of dripwater mg ca sr ca and 13 c from several drips at our site are not correlated with rainfall variability indicative of a relatively weak relationship between hydroclimate and dripwater geochemistry at our site however combining all of the dripwater geochemical data gathered over four field trips to our site n 300 samples we find that drips with highly variable mg sr ca have relatively invariable 18 o values close to the mean we hypothesize that increased residence times translate into reduced variance in dripwater 18 o through mixing in the epikarst as well as increased mg sr ca values through increased calcite precipitation in the epikarst mg ca sr ca and 13 c time series from three overlapping stalagmites that grew over the last 27 kyrs are characterized by strong centennial scale variations and bear little resemblance to previously published well reproduced 18 o time series from the same stalagmites the only shared signal among the three stalagmites geochemical time series is a relative decrease of 1 in 13 c from the last glacial maximum to the holocene consistent with a transition from savannah c4 to rainforest c3 conditions documented in nearby records taken together our study indicates that stalagmite mg sr ca ratios are poor indicators of hydroclimate conditions at our site while stalagmite 13 c exhibits some reproducible signals on glacial interglacial timescales

high rate injection is associated with the increase in u s mid continent seismicity an unprecedented increase in earthquakes in the u s mid continent began in 2009 many of these earthquakes have been documented as induced by wastewater injection we examine the relationship between wastewater injection and u s mid continent seismicity using a newly assembled injection well database for the central and eastern united states we find that the entire increase in earthquake rate is associated with fluid injection wells high rate injection wells 300 000 barrels per month are much more likely to be associated with earthquakes than lower rate wells at the scale of our study a well s cumulative injected volume monthly wellhead pressure depth and proximity to crystalline basement do not strongly correlate with earthquake association managing injection rates may be a useful tool to minimize the likelihood of induced earthquakes

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

elastic wave velocities and permeability of cracked rocks abstract cracks play a major role in most rocks submitted to crustal conditions mechanically cracks make the rock much more compliant they also make it much easier for fluid to flow through any rock body relying on fracture mechanics and statistical physics we introduce a few key concepts which allow to understand and quantify how cracks do modify both the elastic and transport properties of rocks the main different schemes which can be used to derive the elastic effective moduli of a rock are presented it is shown from experimental results that an excellent approximation is the so called non interactive scheme the main consequences of the existence of cracks on the elastic waves is the development of elastic anisotropy due to the anisotropic distribution of crack orientations and the dispersion effect due to microscopic local fluid flow at a larger scale macroscopic fluid flow takes place through the crack network above the percolation threshold two macroscopic fluid flow regimes can be distinguished the percolative regime close to the percolation threshold and the connected regime well above it experimental data on very different rock types show both of these behaviors

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

trace elements in speleothems as recorders of environmental change speleothems are now established as important palaeoenvironmental archives and contain a number of suitable proxies although trace elements have been much less widely used than oxygen and carbon isotopes the complexity of the cave environment helps to explain this since the fluids from which speleothems form vary greatly in composition in space even within a cave chamber seasonally and over longer periods understanding the forcing factors for this variability is the key to decoding the significance of the trace element records a variety of techniques are available for trace element work and it is important to understand the strengths and limitations of each and also to seek an understanding e g by micro imaging techniques of whether the elements are associated with inclusions in the caco3 or are isolated within the crystal lattice for some elements there is a more or less predictable relationship between element ratios to ca in the water and in the calcite individual trace elements may be derived from atmospheric deposition superficial deposits or bedrock and can be recycled in soil processes before being transferred to the cave some components show an instantaneous response to water infiltration whereas others are only leached by slow flowing seepage waters changing in the proportion of water from fracture fed and seepage flow aquifer compartments is an important factor in influencing trace element supply high flows lead to higher fluxes of soil derived colloidally transported elements conversely under relatively dry conditions degassing of co2 results in prior calcite precipitation upflow of the site of speleothem deposition and leads to higher ratios of sr ca and mg ca some trace element variations in speleothems over time are induced during crystal growth whereby faster growth leads to a greater departure from equilibrium element partitioning despite the demonstrated temperature dependence of mg partitioning into calcite attempts at deriving palaeotemperature records from speleothems have been so far confounded by variations in solution mg ca and or crystallographic effects a number of case studies have effectively used trace elements such as speleothem mg as records of palaeo aridity using supporting arguments from modern monitoring or covariations with other parameters such as stable isotopes sr and u isotopes can also be indicators of palaeohydrology although sr isotope variations can also reflect varying aeolian input considerable progress has been made in decoding the meaning of annual trace element variations using criteria for understanding dripwater hydrology and ph this should lead in the future to more specific interpretations of how seasonality evolves through time

testing theoretically predicted stalagmite growth rate with recent annually laminated samples implications for past stalagmite deposition annually laminated stalagmites deposited over the last 30 160 years are analysed to determine their growth rate three natural and artificial cave sites in england france and belgium were chosen for their wide range of variability in growth rate determining variables and multiple samples were taken from each site the annual nature of laminae deposition within the stalagmite calcite was confirmed by comparison to the date of cave void opening 14c analyses or by using dated event horizons measured stalagmite growth rate was determined from annual laminae thickness measurements and compared to that theoretically predicted from the chemical kinetics of the calcite precipitation reaction a good agreement is observed between empirical observations and theoretical predictions although two complicating factors variations in calcite porosity and seasonal cessation of the water supply to the samples both affect the growth rate implications for the extraction of palaeoclimate information from stalagmite growth rate are discussed

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

climate dynamics during the penultimate glacial period recorded in a speleothem from kanaan cave lebanon central levant little is known about terrestrial climate dynamics in the levant during the penultimate interglacial glacial period to decipher the palaeoclimatic history of the marine oxygen isotope stage mis 6 glacial period a well dated stalagmite 194 to 154 ka from kanaan cave on the mediterranean coast in lebanon was analyzed for its petrography growth history and stable isotope geochemistry a resolved climate record has been recovered from this precisely u th dated speleothem spanning the late mis 7 and early mis 6 at low resolution and the mid mis 6 at higher resolution the stalagmite grew discontinuously from 194 to 163 ka more consistent growth and higher growth rates between 163 and 154 ka are most probably linked to increased water recharge and thus more humid conditions more distinct layering in the upper part of the speleothem suggests strong seasonality from 163 ka to 154 ka short term oxygen and carbon isotope excursions were found between 155 and 163 ka the inferred kanaan cave humid intervals during the mid mis 6 follow variations of pollen records in the mediterranean basins and correlate well with the synthetic greenland record and east asian summer monsoon interstadial periods indicating short warm wet periods similar to the dansgaard oeschger events during mis 4 3 in the eastern mediterranean region

calcium isotopes in caves as a proxy for aridity modern calibration and application to the 8 2 kyr event abstract we present the first study of ca isotope cycling in a natural cave system with measurements of bedrock dripwater and recently formed carbonate coupled to a first stalagmite time series spanning the 8 2 kyr event dripwaters at heshang cave central china 30 27 n 110 25 e are isotopically heavy relative to the dolomite bedrock the result of prior calcite precipitation pcp occurring earlier in the drip flow path a simple rayleigh fractionation model quantifies the extent of pcp in the modern environment at 36 ca removal the observed in situ calcium isotope fractionation factor between dripwater and carbonate is 44 42 ca 0 63 0 03 and does not vary during the annual cycle measurements of speleothem carbonate spanning the 8 2 kyr event show the response of ca isotopes to changing climate 44 42ca increases by 0 35 at the onset of the event coeval with changes in 18o and mg ca and remains high for 80 yr this change is explained by decreased rainfall leading to increased pcp an interpretation supported by established pcp proxies mg ca sr ca and ba ca ca isotopes indicate that pcp increased to 60 ca removal during the event which from application of a simple box model suggests mean annual rainfall decreased by approximately a third in central china during the 8 2 kyr event the response of ca isotopes across this event demonstrates their potential for the assessment of past conditions including past dripwater flow rates and rainfall

trace element variations in an annually layered stalagmite as recorders of climatic changes and anthropogenic pollution in central china abstract we analyzed variations in the sr ca ba ca ree ca ree rare earth element zn ca and pb ca ratios preserved in an annually layered stalagmite xl21 from central china the stalagmite record spans the 95 year period ad 1914 2008 the sr ca and ba ca ratios have a significant positive correlation with the stalagmite s growth rate suggesting that they were primarily controlled by growth rate variations variations in ree ca ratios are consistent with local temperature changes suggesting temperature influenced ree concentrations in the stalagmite over decadal to annual timescales higher temperature in this humid area can increase vegetation cover microbial activity and organic decomposition in the soil resulting in enhanced pco2 organic matter concentration and reduced ph and consequently increased ree mobilization from the overlying soil layer and host rock higher temperatures may also increase the natural zn mobilization from the overlying soil mediated by organic matter and consequently may have led to increased zn retention in xl21 an increasing trend is seen in the pb ca ratios from xl21 since 1985 which is consistent with increased lead production in this area and indicates an increase in mine derived lead pollution in the local environment over the past 30 years

induced seismic deformation in the cogdell oil field of west texas a sequence of induced earthquakes occurred at the cogdell oil field in west texas from about 1974 to 1982 the earthquakes occurred within an array of injecting wells which surrounded the perimeter of the field and which decreased in radius during the life of the injection project we examine this sequence of earthquakes in terms of two failure models in the first model seismic failure occurs when and where fluid pressures exceed some critical value in the second model earthquakes occur at the edges of low fluid pressure areas where stresses have been transferred as a result of aseismic deformation in adjacent high fluid pressure regions we calculate the history of fluid pressures in the cogdell field using the theis equation for fluid flow in an areally infinite aquifer the calculations show that the earthquakes occur in a region of relatively low pressure surrounded by regions of higher fluid pressure the cogdell earthquakes may occur on pre existing faults however fluid pressures are sufficiently high in surrounding portions of the field to also produce failure a long time delay between the start of injection and the onset of seismicity may correspond to the time required for fluid pressures on a pre existing fault to reach critical values or may be the result of an evolving injection pattern whereby the inward migration of injecting wells produces aseismic failure which loads stress onto stronger regions within the center of the field injection of fluids for secondary recovery occurs at over three thousand sites in the state of texas many of these sites are geographically near cogdell and many have higher injection pressures and volumes of injected fluid than cogdell however they do not exhibit any seismicity a failure model which incorporates stress loading suggests that the perimeter injection pattern is responsible for the onset of seismicity a consequence of this interpretation is that many other injection fields may be undergoing large amounts of aseismic deformation

unsaturated zone hydrology and cave drip discharge water response implications for speleothem paleoclimate record variability summary high frequency spatially dense discharge monitoring was conducted over fifteen months to characterise unsaturated zone flow at harrie wood cave hwc in the snowy mountains yarrangobilly se australia the cave was formed in the late silurian yarrangobilly limestone a fractured rock associated with very low primary porosity due to past diagenesis over our monitoring period we simultaneously measured rainfall soil moisture saturation and drip discharge rate at fourteen sites to characterise infiltration discharge relationships all drip discharge sites exhibited non gaussian distributions indicating long periods where low discharge predominates punctuated by short infrequent periods of high discharge however there was significant variability in discharge between sites and consequently no spatial correlation in the cave we investigated the depth discharge relationship at hwc and found a moderate relationship between depth and drip discharge lag response times to soil moisture content but only weak relationships between depth and mean and maximum discharge this highlights that the karst architecture plays an important role in controlling drip discharge dynamics principal component analysis pca and agglomerative hierarchal clustering ahc were used to classify similar drip types revealing five unique drip regimes two phase flow and non linear response to recharge behaviour were observed suggesting secondary porosity is controlling unsaturated zone flow in mature limestone environments with low primary porosity using the data presented here the first coupled conceptual and box hydrological flow model was developed this study highlights the heterogeneous nature of hydrological flow in karst and the need to understand unsaturated zone hydrology at the individual drip discharge level to inform speleothem studies for high resolution paleoclimate reconstruction

phosphatic precipitates associated with actinomycetes in speleothems from grand cayman british west indies abstract calcitic speleothems from a cave located on the north central coast of grand cayman commonly include corrosion surfaces that developed when calcite precipitation ceased and corrosion mediated by condensates became the operative process dissolution features associated with these surfaces including etched crystal surfaces microcavities and solution widened boundaries between crystals are commonly occupied by microbes and microbial mats that have been replaced by calcium phosphate and or coated with calcium phosphate no mineralized microbes were found in the calcite crystals that form the speleothems the morphology of the mineralized hyphae eight morphotypes and spores nine morphotypes are indicative of actinomycetes a group of microbes that are ideally adapted to life in oligotrophic cave environs superb preservation of the delicate hyphae aerial hyphae and delicate ornamentation on the hyphae and spores indicate that the microbes underwent rapid mineralized while close to their original life positions although these actinomycetes were extremely susceptible to replacement by calcium phosphate there is no evidence that they directly or indirectly controlled precipitation nevertheless the association between the p rich precipitates and microbes shows that the use of phosphorus as a proxy for seasonal climate changes in paleoclimate analyses must be treated with caution

anthropogenic seismicity rates and operational parameters at the salton sea geothermal field geothermal power is a growing energy source however efforts to increase production are tempered by concern over induced earthquakes although increased seismicity commonly accompanies geothermal production induced earthquake rate cannot currently be forecast on the basis of fluid injection volumes or any other operational parameters we show that at the salton sea geothermal field the total volume of fluid extracted or injected tracks the long term evolution of seismicity after correcting for the aftershock rate the net fluid volume extracted injected provides the best correlation with seismicity in recent years we model the background earthquake rate with a linear combination of injection and net production rates that allows us to track the secular development of the field as the number of earthquakes per fluid volume injected decreases over time

controls on trace element partitioning in cave analogue calcite abstract we report trace element data from a series of carbonate growth experiments in cave analogue conditions in the laboratory with the goal of better understanding environmental controls on trace element incorporation in stalagmites the experimental setup closely mimics natural processes e g precipitation driven by co2 degassing low ionic strength solution thin solution film but with a tight control on growth conditions temperature pco2 drip rate calcite saturation index and the composition of the initial solution calcite is dissolved in deionized water in a 20 000 ppmv pco2 environment with trace elements li na mg co sr cd ba u at appropriate concentrations to mimic natural cave drip waters this solution is dripped onto glass plates coated with seed calcite in a lower pco2 environment at 7 15 25 and 35 c and drip rates of 2 6 and 10 drips per minute d sr was shown to be statistically invariant over the full range of temperature and growth rate studied no relationship between sr ca and growth rate is therefore expected in stalagmite samples over comparable growth rates d mg has a relationship with temperature defined by d mg 0 01e0 02 0 006 t but temperature is not expected to be the dominant control on mg ca in cave calcite due to the larger impact of calcite precipitation on mg ca over short timescales in conditions where temperature is well buffered the fraction of calcium remaining in solution f is likely to be the dominant control on mg ca and other trace element ratios but differences in the response of trace elements to f and t may allow their combined use to assess past cave conditions high cd castalagmite is particularly indicative of low amounts of prior calcite precipitation and cd ca would be a useful addition to trace element studies of natural stalagmites significant scatter is observed in trace element ratios during the laboratory experiments which cannot be explained by simple rayleigh distillation this scatter is well explained by solution mixing and by the mixing of calcite with different fractions of calcite growth accounting for the effects of mixing on trace element concentrations or ratios may help to achieve more robust interpretations of stalagmite chemistry as part of a multi proxy approach to assessment of past environments

seismic evidence for rock damage and healing on the san andreas fault associated with the 2004 m 6 0 parkfield earthquake we deployed a dense linear array of 45 seismometers across and along the san andreas fault near parkfield a week after the m 6 0 parkfield earthquake on 28 september 2004 to record fault zone seismic waves generated by aftershocks and explosions seismic stations and explosions were co sited with our previous exper iment conducted in 2002 the data from repeated shots detonated in the fall of 2002 and 3 months after the 2004 m 6 0 mainshock show 1 0 1 5 decreases in seismic wave velocity within an 200 m wide zone along the fault strike and smaller changes 0 2 0 5 beyond this zone most likely due to the coseismic damage of rocks during dynamic rupture in the 2004 m 6 0 earthquake the width of the damage zone characterized by larger velocity changes is consistent with the low velocity waveguide model on the san andreas fault near parkfield that we derived from fault zone trapped waves li et al 2004 the damage zone is not symmetric but extends farther on the southwest side of the main fault trace waveform cross correlations for repeated aftershocks in 21 clusters with a total of 130 events located at different depths and distances from the array site show 0 7 1 1 increases in s wave velocity within the fault zone in 3 months starting a week after the earthquake the velocity recovery indicates that the damaged rock has been healing and regaining the strength through rigidity recovery with time most likely due to the closure of cracks opened during the mainshock we estimate that the net decrease in seismic velocities within the fault zone was at least 2 5 caused by the 2004 m 6 0 parkfield earthquake the healing rate was largest in the earlier stage of the postmainshock healing process the magnitude of fault healing varies along the rupture zone being slightly larger for the healing beneath middle mountain correlating well with an area of large mapped slip the fault healing is most promi nent at depths above 7 km

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

annual growth banding in a cave stalagmite the presence of microscopic luminescence banding in cave calcite deposits speleothems has recently been reported1 3 the luminescence seems to be caused by excitation of humic and fulvic acids derived from the overlying soil and subsequently incorporated into the calcite3 4 we have tested whether such luminescence corresponds to annual growth layers using high precision thermal ionization mass spectrometric 238u 234u 230 th ages from banded sections of a holocene stalagmite we report here that the timespans yielded by counting bands on the assumption that they are annual agree within error limits with those obtained by our uranium thorium dating this demonstration that the banding is annual should make banded speleothems valuable resources for providing high resolution records of past climate in which precipitation can be estimated from growth rates5 6 and temperatures from stable isotope measurements7 and solar terrestrial correlations as the luminescence intensity can be related to the solar sunspot cycle1 3

influence of pore pressure on velocity in low porosity sandstone implications for time lapse feasibility and pore pressure study as seismic data quality improves time lapse seismic data is increasingly being called upon to interpret and predict changes during reservoir development and production since pressure change is a major component of reservoir change during production a thorough understanding of the influence of pore pressure on seismic velocity is critical laboratory measurements show that differential pressure overburden minus fluid pressure does not adequately determine the actual reservoir conditions changes in fluid pressure are found to have an additional effect on the physical properties of rocks the effective stress coefficient n is used to quantify the effect of pore pressure compared to confining pressure on rock properties however the current practice in time lapse feasibility studies reservoir pressure inversion and pore pressure prediction is to assume that n 1 laboratory measurements reported in both this and previous research show that n can be significantly less than unity for low porosity rocks and that it varies with porosity rock texture and wave type we report the results of ultrasonic experiments to estimate n for low porosity sandstones with and without microcracks our results show that for p waves n is as low as 0 4 at a differential pressure of 20 mpa about 3000 psi for a low porosity sandstone thus in pore pressure inversion an assumption of n 1 would lead to a 150 underestimation of the pore pressure comparison of the effective stress coefficient for fractured and unfractured samples suggests that the presence of microfractures increases the sensitivity of p wave velocity to pore pressure and therefore the effective stress coefficient our results show that the effective stress coefficient decreases with the differential pressure with a higher differential pressure resulting in a lower effective stress coefficient while the effective stress coefficient for p wave velocity can be significantly less than unity it is close to one for s waves

influence of macro fractures and micro fractures on permeability and elastic wave velocities in basalt at elevated pressure fractures are ubiquitous on all scales in crustal rocks the investigation of fractures and their influence on physical and transport properties of rocks is therefore essential for understanding of many key problems in seismology volcanology and rock engineering in crystalline rocks pore water is primarily stored in and migrates through networks of cracks and fractures at all scales it is therefore essential to know how fluid flow in such fracture networks responds to the elevated pressures found at depth here we report results from an investigation of changes in fluid permeability and associated changes in p wave and s wave velocities at elevated effective pressure for intact macro fractured and micro fractured samples of seljadur basalt in all cases permeability decreases and both wave velocities increase with increasing effective pressure permeability decreases were smallest in the intact material from approximately 10 19 m 2 to 3 x 10 20 m 2 intermediate in the micro fractured material from approximately 5 x 10 17 m 2 to 1 x 10 17 m 2 and largest in the macro fractured material from approximately 3 x 10 15 m 2 to 9 x 10 19 m 2 for a material containing both micro fractures and macro fractures the closure of macro fractures dominated the permeability reduction at low pressure with the closure of micro fractures exerting an increasing influence at higher pressure c 2010 elsevier b v all rights reserved

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

estimating rock porosity and fluid saturation using only seismic velocities evaluation of the fluid content in deep earth reservoirs or fluid contaminants in shallow earth environments has required the use of geophysical imaging methods such as seismic reflection prospecting interpretation of seismic velocities and amplitudes is based on theories of fluid saturated and partially saturated rocks that have been available since the 1950s here we present a new synthesis of the same physical concepts that uses compressional wave velocities together with shear wave velocities in a scheme that is much simpler to understand and apply yet yields detailed information about porosity and fluid saturation magnitudes and spatial distribution the key idea revolves around the fact that the density and the lame elastic parameter are the only two parameters determining seismic velocities that also contain information about fluid saturation at low enough frequencies gassmann s well known equations show that the shear modulus is independent of the fluid saturation level we use these facts to

evidence for holocene changes in australian indonesian monsoon rainfall from stalagmite trace element and stable isotope ratios abstract trace element and stable isotope ratios from an active stalagmite lr06 b1 recovered from liang luar cave on the island of flores eastern indonesia are used to reconstruct the position of the austral summer inter tropical convergence zone and australian indonesian summer monsoon variability during the holocene uranium series dating of the stalagmite shows that it commenced growth 12 640 years ago with hiatuses spanning 8 560 to 6 420 and 3 670 to 2 780 years ago stalagmite mg ca and sr ca ratios correlate significantly with one another and with 18 o and 13 c throughout the record this suggests that the mg ca and sr ca ratios are dominated by prior calcite precipitation a process whereby degassing in the vadose zone during periods of low recharge causes deposition of calcite and disproportionate loss of ca 2 ions relative to mg 2 and sr 2 upstream of the stalagmite the degree of initial 234 u 238 u disequilibrium also appears to have been controlled by recharge to the overlying aquifer together with the mg ca sr ca and 18 o values the initial uranium isotope activity ratios 234 u 238 u i imply a generally drier early holocene coincident with a lower sea level and lower southern hemisphere summer insolation comparison of speleothem 18 o time series from flores and borneo shows that they vary in unison for much of the holocene however there is a significant decrease in the borneo 18 o record 6 000 to 4 000 years ago that does not occur in the flores record this anomaly may be related to a change in the australian indonesian summer monsoon circulation in response to a protracted positive phase of the indian ocean dipole under this scenario stronger upwelling off of western indonesia would based on present day effects result in reduced summer convective activity over flores and a subsequent northward shift of the intertropical convergence zone

speleothem trace element signatures a hydrologic geochemical study of modern cave dripwaters and farmed calcite trace element variations in ancient cave speleothems are often interpreted as indicators of changes in paleo rainfall and hydrologic conditions however these records are difficult to interpret without an understanding of the physicochemical controls on stalagmite chemistry plus site specific calibration of changes in net rainfall to variations in dripwater and speleothem chemistry in this study we examine geochemical relationships between net rainfall precipitation minus evapotranspiration p et drip rates drip water chemistry and contemporaneous calcite chemistry to test the hypothesis that speleothem mg ca and sr ca records are proxies for rainfall amount hrc is contained within four low magnesium limestone units capped sporadically by a remnant dolomitic limestone aqueous concentrations of magnesium post evapotranspiration decrease with increasing vertical travel distance between the soil zone and the point of in cave drip emergence drip path length dpl as dissolved high mg solutions sourced from the dolomitic caprock are diluted with dissolved low mg limestone waters sourced from the host limestone dripwater mg ca and sr ca ratios covary and provide diagnostic indicators of the two dominant mechanisms controlling dripwater chemistry 1 mixing of post evaporative solutions derived from two geochemical endmembers dissolution of dolomite and limestone and 2 evolution of hydrochemistry away from dissolved bedrock compositions due to prior calcite precipitation pcp above the drip sites by resolving the linear mixing relationships for drip water mg ca and sr ca sources and the distribution coefficients for trace element transfer in the pcp dripwater to calcite precipitation reactions and applying these principles to our time series we find that the extent of pcp production within the karst is directly controlled by the balance between precipitation p and evapotranspiration et higher net rainfall p et 1 wet conditions reduces pcp and lower net rainfall with increased evapotranspiration p et 1 increases pcp farmed calcite x ca ratios faithfully track hydrologically influenced seasonal variations in dripwater chemistry for x mg sr and na however the relationship between changes in net rainfall and changes in mg ca and sr ca ratios in modern calcite is unique at each site and differs significantly at closely spaced drip stalagmite locations this suggests that in situ modern hydrochemical calibrations should be performed atop individual speleothems prior to harvesting for paleoclimate investigations and that such calibrations may not reflect past conditions as drip paths change we apply this understanding to published dripwater data and speleothem time series from other caves a major implication is that in order to interpret stalagmite sr ca and mg ca ratios as wet vs dry proxies speleothem sr ca and mg ca variations must be coherent and in phase over all time periods i e sr mg ratios must be constant these criteria will help to distinguish rainfall amount versus rainfall source in speleothem 18o records

fluid mobility and frequency dependent seismic velocity direct measurements the influence of fluid mobility on seismic velocity dispersion is directly observed in laboratory measurements from seismic to ultrasonic frequencies a forceddeformation system is used in conjunction with pulse transmission to obtain elastic properties at seismic strain amplitude 10 7 from 5 hz to 800 khz varying fluid types and saturations document the influence of pore fluids the ratio of rock permeability to fluid viscosity defines mobility which largely controls pore fluid motion and pore pressure in a porous medium high fluid mobility permits pore pressure equilibrium either between pores or between heterogeneous regions resulting in a low frequency domain where gassmann s equations are valid in contrast low fluid mobility can produce strong dispersion even within the seismic band here the low frequency assumption fails since most rocks in the general sedimentary section have very low permeability and fluid mobility shales siltstones tight limestones etc most rocks are not in the lowfrequency domain even at seismic frequencies only those rocks with high permeability porous sands and carbonates will remain in the low frequency domain in the seismic or sonic band

mapping pressurized volcanic fluids from induced crustal seismic velocity drops volcanic eruptions are caused by the release of pressure that has accumulated due to hot volcanic fluids at depth here we show that the extent of the regions affected by pressurized fluids can be imaged through the measurement of their response to transient stress perturbations we used records of seismic noise from the japanese hi net seismic network to measure the crustal seismic velocity changes below volcanic regions caused by the 2011 moment magnitude m w 9 0 tohoku oki earthquake we interpret coseismic crustal seismic velocity reductions as related to the mechanical weakening of the pressurized crust by the dynamic stress associated with the seismic waves we suggest therefore that mapping seismic velocity susceptibility to dynamic stress perturbations can be used for the imaging and characterization of volcanic systems

modeling speleothem δ13c variability in a central sierra nevada cave using 14c and 87sr 86sr abstract carbon isotopes in speleothems can vary in response to a number of complex processes active in cave systems that are both directly and indirectly related to climate progressing downward from the soil zone overlying the cave these processes include soil respiration fluid rock interaction in the host limestone degassing of co2 and precipitation of calcite upflow from the speleothem drip site and calcite precipitation at the drip site here we develop a new approach to independently constrain the roles of water rock interaction and soil processes in controlling stalagmite 13c this approach uses the dead carbon proportion dcp estimated from coupled 14c and 230th u measurements in conjunction with sr isotope analyses on stalagmite calcite from a central sierra nevada foothills cave in california a region characterized by a highly seasonal mediterranean type climate to determine the roles of water rock interaction and soil processes in determining stalagmite 13c increases in stalagmite dcp between 16 5 and 8 8 ka are coincident with decreased 13c indicating a varying yet substantial contribution from the soil organic matter som reservoir likely due to significantly increased average age of som in the soil veneer above the cave during wet climatic intervals we use geochemical and isotope mixing models to estimate the host carbonate contribution throughout the 13c time series and determine the degree of degassing and calcite precipitation that occurred prior to precipitation of stalagmite calcite the degree of degassing and prior calcite precipitation we calculate varies systematically with other climate indicators with less degassing and prior calcite precipitation occurring during wetter climatic intervals and more during drier intervals modeled 13c values and degassing calculations suggest that some degree of prior calcite precipitation is necessary at all time intervals to explain measured stalagmite 13c values even during relatively wet intervals these results illustrate the importance of constraining degassing and prior calcite precipitation in the interpretation of speleothem 13c records particularly those from caves that formed in seasonal semi arid to arid environments

evidence of rainfall variations in southern brazil from trace element ratios mg ca and sr ca in a late pleistocene stalagmite trace element ratios in the bt2 stalagmite from botuveracave southern brazil are explored as a proxy for changes in the local rainfall recharge during the last 116 ky bp mg ca and sr ca ratios measured with an electron microprobe are signif icantly positively correlated with one another throughout the entire record and vary in a way that is very consistent with variations of d 18 o in the same speleothem during the last glacial period we suggest that prior calcite precipitation in the vadose zone of the cave system is the main factor affecting the incorporation of mg and sr into calcite of the stalagmite this interpretation is supported by trace element correlation patterns and by results from a hydrochemistry study performed in a cave located in the same region and in a similar environmental setting therefore we conclude that higher lower mg ca and sr ca values are associated with lower higher levels of recharge into the karstic aquifer as such conditions lead to an increase decrease in the volume of calcite precipitated in the unsaturated zone above the cave during dry wet climate periods trace element variations point to generally dryer wetter conditions during lower high phases of summer insolation in the southern hemisphere these periods coincide with decreased increased activity of the south american summer monsoon as revealed by d 18 o stalagmite records in addition trace element variations show that rather wet conditions persisted through out most of the last glacial period from approximately 70 to 17 ky bp we suggest that during this period the glacial boundary conditions especially ice volume buildup in the northern hemisphere played an important role for monsoon rainfall inten sification in the region 2007 elsevier ltd all rights reserved

the geochemistry of carbonate diagenesis the past present and future stable carbon and oxygen isotopes 18o and 13c values and trace elements have been applied to the study of diagenesis of carbonate rocks for over 50 years as valuable as these insights have been many problems regarding the interpretation of geochemical signals within mature rocks remain for example while the 18o values of carbonate rocks are dependent both upon the temperature and the 18o value of the fluid and additional information including trace element composition aids in interpreting such signals direct evidence of either the temperature or the composition of the fluids is required such information can be obtained by analysing the 18o value of any fluid inclusions or by measuring the temperature using a method such as the clumped isotope technique such data speak directly to a large number of problems in interpreting the oxygen isotope record including the well known tendency for 18o values of carbonate rocks to decrease with increasing age unlike the 18o 13c values of carbonates are considered to be less influenced by diagenesis and more a reflection of primary changes in the global carbon cycle through time however many studies have not sufficiently emphasized the effects of diagenesis and other post depositional influences on the eventual carbon isotopic composition of the rock with the classic paradigm that the present is the key to the past being frequently ignored finally many additional proxies are poised to contribute to the interpretation of carbonate diagenesis although the study of carbonate diagenesis is at an exciting point with an explosion of new proxies and methods care should be taken to understand both old and new proxies before applying them to the ancient record

carbon transfer dynamics from bomb 14c and δ13c time series of a laminated stalagmite from sw france modelling and comparison with other stalagmite records twenty two ams 14c measurements have been made on a modern stalagmite from sw france in order to reconstruct the 14c activity history of the calcite deposit annual growth laminae provides a chronology up to 1919 a d results show that the stalagmite 14c activity time series is sensitive to modern atmosphere 14c activity changes such as those produced by the nuclear weapon tests the comparison between the two 14c time series shows that the stalagmite time series is damped its amplitude variation between pre bomb and post bomb values is 75 less and the time delay between the two time series peaks is 16 years 3 a model is developed using atmosphere 14c and 13c data fractionation processes and three soil organic matter components whose mean turnover rates are different the linear correlation coefficient between modeled and measured activities is 0 99 these results combined with two other stalagmite 14c time series already published and compared with local vegetation and climate demonstrate that most of the carbon transfer dynamics are controlled in the soil by soil organic matter degradation rates where vegetation produces debris whose degradation is slow the fraction of old carbon injected in the system increases the observed 14c time series is much more damped and lag time longer than that observed under grassland sites the same mixing model applied on the 13c shows a good agreement r2 0 78 between modeled and measured stalagmite 13c and demonstrates that the suess effect due to fossil fuel combustion in the atmosphere is recorded in the stalagmite but with a damped effect due to som degradation rate the different sources of dead carbon in the seepage water are calculated and discussed

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

influence of shear and deviatoric stress on the evolution of permeability in fractured rock 1 the evolution of permeability in fractured rock as a function of effective normal stress shear displacement and damage remains a complex issue in this contribution we report on experiments in which rock surfaces were subject to direct shear under controlled pore pressure and true triaxial stress conditions while permeability was monitored continuously via flow parallel to the shear direction shear tests were performed in a pressure vessel under drained conditions on samples of novaculite arkansas and diorite coso geothermal field california the sample pairs were sheared to 18 mm of total displacement at 5 mm s at room temperature and at effective normal stresses on the shear plane ranging from 5 to 20 mpa permeability evolution was measured throughout shearing via flow of distilled water from an upstream reservoir discharging downstream of the sample at atmospheric pressure for diorite and novaculite initial preshear fracture permeability is 0 5 1 10 14 m 2 and largely independent of the applied effective normal stresses these permeabilities correspond to equivalent hydraulic apertures of 15 20 mm because of the progressive formation of gouge during shear the postshear permeability of the diorite fracture drops to a final steady value of 0 5 10 17 m 2 the behavior is similar in novaculite but the final permeability of 0 5 10 16 m 2 is obtained only at an effective normal stress of 20 mpa

annually laminated sequences in the internal structure of some belgian stalagmites importance for paleoclimatology abstract fifteen stalagmites from four caves and one sealed tunnel in southern belgium are composed of alternations of annually deposited white porous and dark compact laminae this is demonstrated by comparing the number of laminae with the local history of the site for modern stalagmites and with radioisotopic ages for late glacial and holocene stalagmites annual cyclicity in the internal structure of these speleothems is explained by the highly seasonal variations of the water excess which influences underground water flow comparison between climatic data and modern stalagmites of a closed tunnel shows that growth laminae can record climatic variations 1 there is a good correlation r 0 84 between lamina thickness in a stalagmite and water excess 2 during years with a high water excess dark compact laminae are more developed which makes the speleothem darker vertical successions of several laminae represent microsequences that may have recorded climatic variations with a time resolution of 1 2 year in a late glacial stalagmite successive laminae microsequences form very regular cycles of 11 years separated by a thick darkcompact lamina it is supposed that as for modern stalagmites the thick dark compact lamina corresponds to a period of high water excess hence this 11 year cycle may reflect a climatic cycle

dating cave drip water by tritium summary speleothems are increasingly used as an archive of past climate but some of the proxy signals encoded in these deposits reflect hydrological characteristics of the karst aquifer and not necessarily climate variability a central aspect in karst hydrology is the time required for the rainwater to reach the point of discharge in a cave e g the tip of the stalactite one promising approach in determining this residence time is drip water dating by tritium 3 h in contrast to traditional tritium dating we do not refer directly to tritium concentrations in precipitation as input function but to an infiltration weighted annual mean of the rainwater values using concentration differences between this infiltration weighted mean and the drip water an age is calculated from the radioactive decay law assuming piston flow the approach was tested in three adjacent caves in northwestern germany which were monitored for about two years all of the studied drip sites yielded drip water ages between 2 and 4 years with uncertainties on the order of 1 year these results were confirmed at several drip sites by oxygen isotope data which show rather constant values with insignificant intra annual variability attempts to apply the 3 h 3 he method resulted in comparable ages despite several complicating factors

hydraulic mechanical properties of microfaults in granitic rock using the punch through shear test abstract fault zones are key features in crystalline geothermal reservoirs or in other subsurface environments due to the fact that they act as main fluid pathways an adequate experimental description of the evolution of permeability of a realistic microscopic fault zone under in situ reservoir and fracture parallel flow conditions is required to address this topic we demonstrate a novel experimental set up punch through shear test that is able to generate a realistic shear zone microfault under in situ reservoir conditions while simultaneously measuring permeability and dilation three samples of intact granite from the odenwald upper rhine graben were placed into a mts 815 tri axial compression cell where a self designed piston assembly punched down the inner cylinder of the sample creating the desired microfault geometry with a given offset permeability was measured and fracture dilation was inferred from an lvdt extensometer chain as well as the balance of fluid volume flowing in and out of the sample after fracture generation the shear displacement was increased to 1 2 mm and pore pressure changes of 5 or 10 mpa were applied cyclically to simulate injection and production scenarios formation of a microfault increased the permeability of the granite rock by 2 to almost 3 orders of magnitude further shear displacement led to a small increase in permeability by a factor of 1 1 to 4 0 but permeability was reduced by a factor of 2 5 to 4 within 16 h due to compaction and fault healing effective pressure cycling led to reversible permeability changes ct images showed that the fracture network is rather complex but depicts all features commonly observed in larger scale fault zones

coping with earthquakes induced by fluid injection large areas of the united states long considered geologically stable with little or no detected seismicity have recently become seismically active the increase in earthquake activity began in the mid continent starting in 2001 1 and has continued to rise in 2014 the rate of occurrence of earthquakes with magnitudes m of 3 and greater in oklahoma exceeded that in california see the figure this elevated activity includes larger earthquakes several with m 5 that have caused significant damage 2 3 to a large extent the increasing rate of earthquakes in the mid continent is due to fluid injection activities used in modern energy production 1 4 5 we explore potential avenues for mitigating effects of induced seismicity although the united states is our focus here canada china the uk and others confront similar problems associated with oil and gas production whereas quakes induced by geothermal activities affect switzerland germany and others

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

the formation and evolution of an isolated submarine valley in the north channel irish sea an investigation of beaufort s dyke beaufort s dyke is a submarine depression located in the north channel of the irish sea with a maximum depth of 312 m the dyke is one of the deepest areas within the european continental shelf integration and interpretation of 450 km of sparker seismic data and full coverage bathymetric data derived from multi beam echo sounder surveys allow for the investigation of the formation processes of beaufort s dyke and the evolution of geomorphological features within it the dyke formed by composite subglacial processes dominated by subglacial meltwater discharge is interpreted as a tunnel valley the regional isolation of beaufort s dyke may be explained by the bounding of the north channel by the bedrock masses of ireland and scotland coupled with the exploitation of structural weakness along a fault plane and presence of halite in the eroded substrate enhancing the erosive potential of the overlying glacier beaufort s dyke has probably been maintained as an open feature by strong rectilinear tidal currents the morphology of lunate sediment waves and a large parabolic bedform towards the south of the dyke contradict the observed dominant s n mean hydrodynamic flow recorded within the north channel suggesting an alternative hydrodynamic regime either within the dyke or during bedform creation

lead concentrations and isotope ratios in speleothems as proxies for atmospheric metal pollution since the industrial revolution abstract lead concentrations and isotope ratios from two speleothems from the han sur lesse cave in southern belgium were measured in order to study the ability of speleothems to act as archives of atmospheric pollution to address this aim we analyzed trace elemental al and pb compositions by la icp ms and icp ms as well as pb isotopes by mc icp ms the results help to identify three intervals characterized by particularly high enrichment of pb from 1880 to 1905 ad from 1945 to 1965 ad and from 1975 to 1990 ad the speleothem record shows similar changes as the known historical atmospheric pollution level in belgium lead isotope ratios discriminate between pb sources and confirm that coal and gasoline combustion combined with regional metallurgical activities were the predominant pb pollution sources in the stalagmites during the last 250 years this study opens possibilities to determine anthropogenic versus natural metal sources in well dated speleothem archives

dead carbon in stalagmites carbonate bedrock paleodissolution vs ageing of soil organic matter implications for 13c variations in speleothems twenty one 14c accelerator mass spectrometric analyses were obtained for three holocene stalagmites from the uamh an tartair cave sutherland scotland in order to estimate the past dead carbon proportion dcp results show that the dcp increases from 22 to 38 from 3780 years ago to the present because 13c variation is small within each sample it is concluded that this dcp increase is the product of the ageing of soil organic matter related to peat bog development above the cave that produced older soil co2 and not from a more intense dissolution of the surrounding carbonates which would have led to a 13c increase comparison with samples from other sites in europe shows no intersite correlation between dcp and 13c but a relatively good intersite correlation is observed between dcp and average site temperature thus temperature may be a major factor controlling the production of old soil organic matter co2 and therefore the dead carbon content of seepage water in contrast to the scotland stalagmites two other holocene samples from sites in southern france and belgium exhibit a good correlation between 13c and dcp which can be explained in terms of variations in the intensity of limestone dissolution consequently 13c variations observed in stalagmites are not always due to changes in the vegetation type c3 c4 as has been commonly assumed 13c 12c variations in speleothem calcite may also be controlled by the soil organic matter age and in some cases by the intensity of the limestone dissolution conversely a largely constant speleothem 13c signal as observed for the scotland stalagmites does not necessarily imply that surface climate and vegetation conditions were stable since the dcp variations in this case are clearly related to the peat bog development during stalagmite growth

in situ measurement of seasonal δ18o variations and analysis of isotopic trends in a modern speleothem from southwest australia we present a record of seasonal and inter annual oxygen o and carbon c isotope ratios from an 81 year old stalagmite from moondyne cave southwest australia the growth history of stalagmite mnd s1 is known since it grew on a cave boardwalk that was installed in 1911 and removed in 1992 this stalagmite provides an excellent test of speleothem climate proxies because the regional climate is strongly seasonal wet winter dry summer and has experienced a 200 mm 20 reduction of mean rainfall since the mid 1960s and a 0 8 c temperature rise since 1953 seasonal variations in calcite o were measured in situ by high spatial resolution ion microprobe whilst inter annual variations of o and c were measured by conventional gas source mass spectrometry comparison of the speleothem stable isotopes and instrumental temperature records reveals that o variations are too large to be driven by temperature alone and are in the opposite sense however daily rainfall o measurements show that the mean seasonal range in o of rainfall in southwest australia is large 2 and inversely correlated with rainfall amount a rainfall driver for the speleothem o is confirmed by the detection of seasonal shifts of 0 7 1 5 in speleothem that track rainfall o smoothed by storage in the overlying limestone the seasonal range in speleothem o is larger than any inter annual and decadal variation observed in the record the prominent annual cycles in speleothem o revealed by ion microprobe analysis indicate that subtle changes in the frequency of intense winter rainfall events or possibly also moisture sources could produce significant changes in mean speleothem o the ion microprobe results also raise the possibility that the masses of speleothem calcite deposited in winter and summer could vary as a function of the seasonal drip rate and carbonate saturation state of these waters if this is the case then small changes in the relative masses of calcite deposited in winter and summer could produce significant shifts in mean o and c that have a complex relation to climate this finding should be generally applicable to the interpretation of long term trends in speleothem geochemical records for shallow cave sites where seasonal variations in geochemical tracers are relatively large including most of the sub tropical monsoon belts and mid to high latitudes with distinct rainfall seasons

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