remotely sensed dune celerity and sand flux measurements of the world s fastest barchans bodele chad quantifying sand flux with field measurements is an expensive and time consuming process we here present an alternative approach using the cosi corr software package for earth surface deformation detection using pairs of aster satellite images we detected dune migration in the bodele depression of northern chad over time intervals of one month to 6 5 years the displacement map can be used to automatically distinguish dunes from interdunes which is a crucial step towards calculating sand flux we interpolated a surface between the interdune areas and subtracted it from a digital elevation model thus obtaining dune heights and volumes multiplying height with celerity yields a pixel by pixel estimate of the sand flux we applied this method to large diatomite dunes in the bodele confirming that these are some of the world s fastest moving barchans plotting dune height against inverse celerity reveals sand flux at the dune crest of 200 m 3 m yr average dune sand flux values for the eastern and western bodele are 76 and 99 m3 m yr respectively the contribution of the dunes to the total area averaged sand flux is 24 29 m 3 m yr which is similar to 10 of the saltation flux determined by previously published field measurements citation vermeesch p and n drake 2008 remotely sensed dune celerity and sand flux measurements of the world s fastest barchans bodele chad geophys res lett 35 l24404 doi 10 1029 2008gl035921

orogen parallel strike slip faults bordering metamorphic core complexes the salzach enns fault zone in the eastern alps austria abstract the approximately ene trending salzach enns fault eastern alps contributed to late stage exhumation of the tauern metamorphic core complex in response to oblique convergence of european and adriatic plates six stages of kinematic evolution with early ductile and later brittle deformational structures were recognized as follows 1 initial ductile deformation is represented by a combination of sinistral shear dominated noncoaxial strain and coaxial strain 2 early brittle sinistral strike slip is combined with a pure shear deformation and represents roughly n s contraction it is followed by 3 sinistral strike slip and 4 ca n s extension due to normal slip striations 5 subsequent n s compression resulted in counterclockwise rotation of the maximum principal stress from ne to nw and led to final dextral strike slip displacements along the salzach enns fault the exhumation of the tauern window was accommodated by dip slip on the fault plane at shallow levels and coaxial flattening at deeper structural levels brittle sinistral faults at shallow structural levels produced a larger amount of strike slip displacement than ductile shear zones at the deeper structural levels which is explained as a scissors like movement and which resulted in the eastward tilting of the tauern window

climate caving in to new chronologies speleothems formed in caves such as stalagmites can be dated precisely and are increasingly providing detailed and accurate records of past climates

speleothern luminescence intensity and spectral characteristics signal calibration and a record of palaeovegetation change abstract the intensity and spectral characteristics of speleothem luminescence are investigated for signs of any potential palaeoenvironmental signals luminescence in speleothems has been demonstrated to have an organic acid source acids being transported from the overlying soil to the speleothem via the groundwater system luminescence spectral characteristics confirm a humic fulvic acid source of the luminescence but are unable to distinguish between plant acids derived from different vegetation systems spectral characteristics also differ between solid and dissolved speleothem calcite the influence of six factors on luminescence intensity are considered changes in organic acid concentration organic acid structural type depth of the sample below the surface dilution effects through changes in water discharge rate dilution effects through changes in speleothem growth rate and the effects of luminescence quenching due to the presence of metal ions in a holocene stalagmite sample from sutherland a period of low luminescence intensity is observed which is demonstrated to correlate with periods of blanket bog expansion recorded in the regional pollen record this suggestion is supported by a study of 18 recently deposited samples from northwest europe and 5 cave water samples feeding stalagmites in a british cave when a relationship to vegetation is evident with very low luminescence intensity observed from sites overlain by blanket bog deposits this is thought to be due to both low organic acid concentrations in feedwaters and also the low luminescence efficiency of the humic acids from bog sites due to their structural characteristics

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

high resolution mapping of uranium and other trace elements in recrystallized aragonite calcite speleothems from caves in the pyrenees france implication for u series dating abstract aragonite and calcite speleothems were sampled in the cave of pierre saint martin pyrenees atlantiques france these speleothems contain significant amounts of uranium and strontium which were measured spatially and chemically by nuclear microprobe analysis sr and u distributions are highly varied with a marked contrast between aragonite and calcite because the aragonite concentrates sr and u on the other hand zn is preferentially located in calcite and in layers of organic matter trapped in caco 3 sr contents ranged from 440 to 1100 g g in the calcite and 4900 to 18 500 g g in the aragonite u concentrations show remarkably high values from 11 to 19 g g in the calcite and 89 to 350 g g in the aragonite these u and sr concentrations are amongst the highest measured in supergene speleothems deposited by infiltrating meteoric waters x ray absorption experiments with synchrotron radiation suggested that uranium was incorporated in its hexavalent oxidation state in both aragonite and calcite recrystallization from aragonite into calcite was indicated by micromorphological observations for some of the samples this recrystallization process may explain the uranium loss in neogenic calcite deposits and consequently the opening of the geochemical system which can lead to errors in age dating with the u series dating method uranium loss in recrystallized calcite is one of the important aspects to be considered in u series dating and more generally for u geochemical stability in caco 3

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

large kinetic isotope effects in modern speleothems the application of stable isotopes in speleothem records requires an understanding of the extent to which speleothem calcite isotopic compositions refl ect the compositions of the cave waters from which they precipitate to test for equilibrium precipitation modern speleothem calcite was grown on glass plates so that the carbon and oxygen isotope composition of the calcite and the water from which it precipitated could be directly compared the plates were placed on the tops of three actively growing stalagmites that occupy a 1 m 2 area in harrison s cave barbados west indies only some of the plate 13 c values and none of the plate 18 o values correspond to equilibrium values indicating signifi cant kinetic isotope effects during speleothem calcite growth we investigate herein mechanisms that may account for the kinetic isotope effects on each plate speleothem calcite was deposited with distinct 18 o and 13 c compositions that increase progressively away from the growth axis with up to 6 6 13 c and 1 7 18 o enrichments the positive 13 c

aeolian contribution to strontium and strontium isotope variations in a tasmanian speleothem abstract a speleothem from south central tasmania shows marked secular variations in its strontium content the element exhibits a striking bimodal distribution pattern with abrupt changes between two modal groups that is believed to be due to rapid changes in the direction of the dominant strong winds strontium isotope compositions in the speleothem range from 0 70865 to 0 70898 indicating derivation of sr from at least two distinct sources the first a persistent one from the overlying limestone the second a higher 87 sr 86 sr component probably representing input from terrestrial dust the speleothem record is unusual because it indicates a greater input of radiogenic sr dust flux during interstadial times than under full glacial conditions if an aeolian origin of some of the strontium contained in speleothems at other inland cave sites around the world can be confirmed variations in strontium isotope composition will provide high resolution records of how terrestrial dust flux has varied during the quaternary in near coastal sites significant amounts of strontium may be derived from seasalt and in those areas temporal variation of the element in speleothems may reflect at least in part changing distance from the coast due to changes in sealevel

a paleoclimate record of the last 17 600 years in stalagmites from the b7 cave sauerland germany abstract petrographical and geochemical parameters of stalagmites from the b7 cave in iserlohn letmathe northern rhenish massif nw germany record late and postglacial climate changes temperature and or precipitation fabrics and microfacies of the stalagmite profiles lead to a differentiation of four hierarchies of rhythms clastic layers in the stalagmites are caused by flooding events and are time markers twenty four tims th u age dates provide a time calibration of stalagmite growth phases one stalagmite reveals an early growth period between 17 6 and 16 7 ka bp between 9 6 and 5 5 ka bp atlantic episode of the holocene the growth rate of the stalagmites was higher than before and after this time with dominant light porous microfacial laminae and high 18 o and 13 c values representing partly kinetic fractionation effects this part of the holocene is interpreted as a mainly warm episode with frequent interruptions of dripping within the past 4 ka the profiles with predominant dark compact facies reveal low isotopic values which may be interpreted as a temperature proxy record the stalagmite records resemble records from an irish stalagmite correlation with the 14 c record from european tree rings suggests that colder periods in the north atlantic were accompanied by drier winters in central europe

modelling fractionation of stable isotopes in stalagmites abstract high resolution 13c and 18o profiles recorded in precisely dated speleothems are widely used proxies for the climate of the past both 13c and 18o depend on several climate related effects including meteorological processes processes occurring in the soil zone above the cave and isotope fractionation processes occurring in the solution layer on the stalagmite surface here we model the latter using a stalagmite isotope and growth model and determine the relationship between the stable isotope values in speleothem calcite and cave parameters such as temperature drip interval water p co 2 and a mixing coefficient describing mixing processes between the solution layer and the impinging drop the evolution of 13c values is modelled as a rayleigh distillation process and shows a pronounced dependence on the residence time of the solution on the stalagmite surface and the drip interval respectively the evolution of 18o values in contrast is also influenced by buffering reactions between the bicarbonate in the solution and the drip water driving the 18o value of the bicarbonate towards the value expected for equilibrium isotope fractionation between drip water and calcite this attenuates the dependence of the 18o values on drip interval the temperature dependence of 18o however is more pronounced than for 13c and in a similar range as expected for fractionation under equilibrium conditions we also investigate the isotopic enrichment of the 13c and 18o values along individual growth layers and thus the slopes expected for hendy tests the results show that a positive hendy test is only possible if isotope fractionation occurred under disequilibrium conditions however a negative hendy test does not exclude that isotope fractionation occurred under disequilibrium conditions a more reliable indicator for disequilibrium fractionation is the enrichment of the 13c values along an individual growth layer

the demise of the last interglacial recorded in isotopically dated speleothems from the alps abstract the transition from interglacial to glacial climate has attracted much attention in paleoclimatic research partly because orbital forcing dictates that such a return to a new ice age is inescapable albeit in the distant future only the detailed series of steps that leads to glacial inceptions remains poorly understood however and studies of past glacial inceptions are often compromised by incomplete records imprecise chronological control and or uncertainties associated with proxy transfer functions here we present results from u th dated speleothems from a cave in the austrian alps entrische kirche cave which grew continuously between ca 127 and 114 ka and intermittently also during subsequent stadials and interstadials the alpine setting of this cave is prone to periglacial and glacial processes as well as temperature and precipitation changes which are recorded in these cave deposits we use high resolution stable isotope data to constrain paleoenvironmental changes associated with the demise of the last interglacial unprecedented in detail for central europe peak interglacial conditions are characterized by high 18 o values and high growth rates from ca 127 to 124 ka a major drop in 18 o by 3 occurred at ca 118 ka which coincided with cold event c26 in the north atlantic this isotopic shift which occurred at or close to isotopic equilibrium cannot be explained by simple uniform cooling modelling suggests that enhanced seasonality dominated by significant changes in winter precipitation are required to reconcile the isotope data with the fact that calcite deposition continued across the mis 5e d transition i e no cave freezing this period of enhanced seasonality lasted for several millennia during which the catchment area of the cave remained geomorphologically stable and ice free eventually speleothem growth terminated at ca 114 ka which is in line with widespread ice rafting in the north atlantic cold event c24 and the onset of fully stadial conditions during mis 5d

global ice volume fluctuations north atlantic ice rafting events and deep ocean circulation changes between 130 and 70 ka multiproxy data from north atlantic deep sea sediment core neap18k provide a detailed record of climate through oxygen isotope stage ois 5 seven distinct large scale episodes of ice rafting c25 c19 were identified between 126 and 70 ka global ice volume reconstructions based on high resolution benthic 18 o records indicate that major ice rafting events were not confined to ice volume maxima at ois 5d and 5b but also occurred during periods of ice sheet growth and disintegration however iceberg discharges were restricted to times when sea levels were 40 65 m below present values ice rafting episode c25 the first large scale cooling of mid atlantic surface waters after the last interglacial occurred during the gradual buildup of continental ice sheets at the ois 5e 5d transition major ice sheet collapses allied to ice rafting events c24 and c21 were associated with rapid sea level increases of 20 and 40 m respectively suborbital climatic fluctuations in the neap18k sedimentary record denoted by prominent 7 5 4 5 and 3 k y cyclicities appear to correlate with both greenland atmospheric temperatures and changes in thermohaline circulation patterns inferred from benthic 13 c values and hence provide clear evidence of a highly interconnected north atlantic climatic regime during ois 5

high resolution record of northern hemisphere climate extending into the last interglacial period high resolution record of northern hemisphere climate extending into the last interglacial period

historical climatic record from flood sediments deposited in the interior of spiralka cave czech republic abstract magnetic susceptibility was measured on more than four hundred samples collected from a 5 m high section of fine grained sediments deposited during flood events in the interior of spiralka cave spiralka cave is located in the northeastern portion of the moravian karst czech republic in the upper 1 5 m of this profile mineral magnetic fe arm sirm s ratio t and other non magnetic measurements heavy mineral concentration loss on ignition and particle grain size indicate that variations are controlled by the concentration of magnetite and by magnetic grain size i e increased magnetic susceptibility results from increased concentration of coarse grained magnetite a positive correlation with ti and zr concentrations in this part of the profile with our magnetic susceptibility record is a detrital signal responding to changing environmental conditions in the catchment area furthermore a comparison of our susceptibility record to the record of winter temperature anomalies constructed from both instrumental and historical records collected at the klementinum observatory in prague shows a remarkable correlation the most probable explanation of these correlations is that during years with warmer winters positive winter temperature anomalies and less snow cover the floods were less intensive but probably had access to larger tracts of cultivated land as agriculture tended to expand during these warmer periods cultivation of the land provided flood waters with greater access to coarser grained magnetite like materials exposed by tilling of soils lower in the profile interpreting the environmental significance of magnetic susceptibility variations is more complex as remobilization of iron has occurred nevertheless the magnetic susceptibility record when coupled with non magnetic measurements can be shown to correlate to known environmental conditions present in central europe during the deposition of the lower portion of the profile

the sahara east mediterranean dust and climate connection revealed by strontium and uranium isotopes in a jerusalem speleothem this paper explores the potential of sr and u isotope systems in speleothems as tracers of eolian dust transport and hydrological conditions the study focuses on a speleothem from jerusalem spanning the past 220 kyr this speleothem provides a precisely dated record of dust flux from the sahara to the east mediterranean enhanced dust flux and terra rossa soil development are reflected by elevated 87sr 86sr ratios in the speleothem 0 7082 0 7086 while lower 87sr 86sr ratios 0 7078 indicate higher contribution of the local bedrock due to low dust flux and low soil accumulation the strontium isotope system in the speleothem is a robust monitor of the sahara monsoon modulated climate since dust uptake is related to development or reduction in vegetation cover of sahara soil the 234u 238u activity ratios in the speleothem range between 1 12 and 1 0 the high activity values may indicate selective removal of 234u from the soil while the low values converge to the bedrock the migration of 234u to the cave reflects mainly the regional hydrological conditions that are modulated by the north atlantic mediterranean climate system thus the speleothem provides a combined record of the monsoon north atlantic climatic systems long term stability in glacial 87sr 86sr ratios 0 7083 0 0001 over the past 220 kyr suggests an overall similarity in eolian dust sources and uniformity in the synoptic conditions that dominate the dust storm tracks during glacial periods

prehistoric maritime migration in the pacific islands an hypothesis of enso forcing long distance human migration across the pacific ocean occurred during the late holocene and originated almost entirely in the west as prevailing tradewinds blow from the east the mechanisms of p

ree3 and mn2 activated cathodoluminescence in lateglacial and holocene stalagmites of central europe evidence for climatic processes combined visual cathodoluminescence cl and spectral analyses of cl reveals periodic enrichments of rare earth elements ree3 and manganese mn2 within the laminations of eight calcitic lateglacial to postglacial stalagmites in the annual layers the enrichment of trace elements can be correlated with the autumn winter laminae which are strongly pigmented and rich in organic carbon during the holocene they occur especially in the atlantic stage and in subrecent recent times the enrichment of ree3 and mn reflects times of more intense weathering which presumably prevailed during the atlantic warm and humid climate in subrecent recent times especially the last 100 years these enrichments may have been at least partially anthropogenically induced

the classic marine isotope substage 5e since its identi cation nearly fty years ago marine iso tope stage 5 mis 5 has been placed onto absolute time scaleson the basis of three independent approaches cesare emiliani who set up the isotope stages emiliani 1955 depended onuranium series dating of the sediments a method that today isregarded as not generally capable of yielding useful precisionor accuracy broecker and van donk 1970 pioneered the ap proach of correlating to radiometrically dated marine coral ter races thishasbeenmuchaidedinrecentyearsbyimprovementsin the precision and accuracy of these age determinations thathave owed from the development of thermal ionization massspectrometry tims for uranium series dating edwards

chronology of the last glacial cycle in the european alps chronological data for glacier advances in the european alps between the last interglacial eemian and the holocene are summarised 115 to 11 ka during this time glaciers were most extensive extending tens of kilometres out onto the forelands between 30 and 18 ka that is synchronous with the global ice volume maximum of marine isotope stage mis 2 evidence for ice expanding to just past the mountain front for an earlier major glacier advance comes from swiss sites where advances have been luminescence dated to mis 5d 100 ka and mis 4 70 ka up to now no such evidence has been found in the eastern alps by 18 ka more than 80 of the late wurmian ice volume had gone subsequently glaciers readvanced reaching into the upper reaches of the main valleys during the lateglacial gschnitz stadial which likely occurred around 17 ka with final moraine stabilisation no later than 15 4 ka the link of the egesen stadial with the younger dryas climate deterioration is supported by exposure ages from four sites as well as minimum limiting radiocarbon dates from bogs within former glacier tongue areas key questions on the spatial and temporal variability of ice extents throughout the last glacial cycle have yet to be answered copyright 2008 john wiley sons ltd

speleothem deposition at the glaciation threshold an attempt to constrain the age and paleoenvironmental significance of a detrital rich flowstone sequence from entrische kirche cave austria abstract proxy records from high altitude locations predating the last glacial maximum are rare but could provide invaluable insights into the response of alpine catchments to the rapid climate fluctuations which characterized the last glacial period here we present a detrital rich flowstone record from entrische kirche cave an inneralpine cave situated close to the accumulation area of the pleistocene ice stream network of the european alps that expanded repeatedly into the lowlands during glacial maxima u th dating of this calcite is challenging due to high detrital th however petrographic and stable isotope analyses in conjunction with associated clastic cave sediments provide useful insights into the climatic boundary conditions during speleothem formation and into the paleoenvironmental processes which operated in the 2000 m high catchment above the cave our data show that millennial scale temperature fluctuations had a first order control on the periglacial activity and vegetation in the catchment which strongly influenced the formation and infiltration of detritus into the karst aquifer the brown laminated and brown dendritic fabrics that compose much of the detrital rich flowstone succession reflect these environmental processes the temperature dependence of periglacial and permafrost processes allows to constrain the amount of cooling relative to the present day mean annual air temperature that is required to initiate detrital rich calcite formation in entrische kirche cave i e 2 5 c minimum to 6 c maximum respectively white inclusion poor calcite that is intercalated with the detrital rich calcite indicates warm interstadial conditions and geomorphological stability in the catchment area one such phase has been u th dated to 88 3 6 9 ka i e greenland interstadial 21 or 22

temporal and spatial variations in periglacial soil movements on alpine crest slopes this paper describes up to ten years of continuous monitoring of frost heave creep and associated parameters on high mountain crest slopes in the japanese and swiss alps aiming to evaluate spatial and interannual variations in the rates and controls of soil movement shallow frost creep re ecting diurnal frost heave activity dominates the crest slopes that lack a vegetation mat and have a thin debris mantle with good drainage seasonal frost heave activity can induce slightly deeper movement where ne soil exists below the depth reached by diurnal freeze thaw penetration although the shallow bedrock impedes movements below 20 cm depth as a result downslope velocity pro les display strong concavity with surface velocities of 2 50 cm a 1 the frost creep rates vary spatially depending on the soil texture slope gradient frequency of temperature cycling across 0 c and moisture availability during freeze thaw periods soil movements recur in every freeze thaw period although with some interannual variations affected by the length of seasonal snow cover and the occurrence of precipitation during freeze thaw periods the swiss alps encounter more signi cant interannual variations than the japanese alps re ecting the large variability of the annual snow regime copyright 2005 john wiley sons ltd

the wingeol lamination tool new software for rapid semi automated analysis of laminated climate archives geological and biological archives showing an annually laminated internal structure are currently top priority in palaeoclimate research as they are recognized as very high resolution archives of environmental change also the annual origin of laminations can be validated by absolute age dating or by using instrumental data for the most recent period microscopic laminae may span several hundreds to thousands of years and frequently reveal a high degree of internal growth variability quantitative examination of laminations using transmitted light or epifluorescence microscopy is thus a tedious task and may be partly automated we developed a software wingeol lamination tool using c capable of semi automatically detecting and measuring individual lamina thicknesses in archives showing large internal growth variability the lamination tool enables the operator to efficiently and quantitatively examine laminae down to the micron scale and it was successfully tested on a variety of annually banded samples

inorganic calcite morphology roles of fluid chemistry and fluid flow abstract evaluation of calcite crystal habits and fabric and their relation to precipitating fluids in spelean environments indicates that habit variations are controlled primarily by degree of supersaturation at less than 6 times supersaturation crystal habits are limited to those with shallow to steep rhombohedral forms i e 1011 4041 with increasing supersaturation scalenohedrons extremely steep rhombohedrons pinacoids and hexagonal prisms are developed slight elongation due to differences in crystal dimensions of these forms may arise i e scalenohedrons versus shallow rhombohedrons at extreme supersaturation 12 times curvature of crystal faces or curved surfaces appear the development of fibrous versus equant fabrics is the result of changes or modification of reactant supply rates and the number of crystallites nuclei present under rapid flow conditions growth rates are accelerated and greater numbers of nuclei are present thus compromise boundaries parallel to c axis and perpendicular to flow and substrate are rapidly attained in the absence of flow fewer crystallites are present and larger well developed crystals or branching forms dictated by saturation conditions arise in the absence of flow at low supersaturation elongate composite crystals and hence fibrous fabrics may result from migration of the fluid crystal interface as a result of changing or oscillating water levels a flow control mechanism can be applied to numerous geological conditions in which transitions from fibrous to equant crystal morphologies are observed

the significance of chemical isotopic and detrital components in three coeval stalagmites from the superhumid southernmost andes 53 s as high resolution palaeo climate proxies abstract stalagmites are important palaeo climatic archives since their chemical and isotopic signatures have the potential to record high resolution changes in temperature and precipitation over thousands of years we present three u th dated records of stalagmites ma1 ma3 in the superhumid southern andes chile 53 s they grew simultaneously during the last five thousand years ka bp in a cave that developed in schist and granodiorite major and trace elements as well as the c and o isotope compositions of the stalagmites were analysed at high spatial and temporal resolution as proxies for palaeo temperature and palaeo precipitation calibrations are based on data from five years of monitoring the climate and hydrology inside and outside the cave and on data from 100 years of regional weather station records water insoluble elements such as y and hree in the stalagmites indicate the amount of incorporated siliciclastic detritus monitoring shows that the quantity of detritus is controlled by the drip water rate once a threshold level has been exceeded in general drip rate variations of the stalagmites depend on the amount of rainfall however different drip water pathways above each drip location gave rise to individual drip rate levels only one of the three stalagmites ma1 had sufficiently high drip rates to record detrital proxies over its complete length carbonate compatible element contents e g u sr mg which were measured up to sub annual resolution document changes in meteoric precipitation and related drip water dilution in addition these soluble elements are controlled by leaching during weathering of the host rock and soils depending on the ph of acidic pore waters in the peaty soils of the cave s catchment area in general higher rainfall resulted in a lower concentration of these elements and vice versa the mg ca record of stalagmite ma1 was calibrated against meteoric precipitation records for the last 100 years from two regional weather stations carbonate compatible soluble elements show similar patterns in the three stalagmites with generally high values when drip rates and detrital tracers were low and vice versa 13c and 18o values are highly correlated in each stalagmite suggesting a predominantly drip rate dependent kinetic control by evaporation and or outgassing only c and o isotopes from stalagmite ma1 that received the highest drip rates show a good correlation between detrital proxy elements and carbonate compatible elements a temperature related change in rainwater isotope values modified the ma1 record during the little ice age 0 7 0 1 ka bp that was 1 5 c colder than today the isotopic composition of the stalagmites ma2 and ma3 that formed at lower drip rates shows a poor correlation with stalagmite ma1 and all other chemical proxies of ma1 hendy tests indicate that the degassing controlled isotope fractionation of ma2 and ma3 had already started at the cave roof especially when drip rates were low changing pathways and residence times of the seepage water caused a non climatically controlled isotope fractionation which may be generally important in ventilated caves during phases of low drip rates our proxies indicate that the neoglacial cold phases from 3 5 to 2 5 and from 0 7 to 0 1 ka bp were characterised by 30 lower precipitation compared with the medieval warm period from 1 2 to 0 8 ka bp which was extremely humid in this region

reconstructing palaeoprecipitation from an active cave flowstone several drill cores were obtained from a laminated actively forming flowstone from a shallow cave in austria highly resolved petrographic and geochemical analyses combined with multi annual cave monitoring reveal a distinct sensitivity of flowstone growth and composition to late holocene meteoric precipitation the regular sub millimetre scale lamination consists of thicker translucent laminae and thinner organic inclusion rich laminae there is also a macroscopic millimetre scale banding of darker and lighter bands comprising several laminae stable isotope analyses of drill cores and modern calcite precipitates show a pronounced positive covariation of 13c and 18o values indicative of kinetic isotope effects comparing the isotope values with petrography shows gradual changes across several of the annual laminae i e changes of several per mille on a multi annual to decadal timescale the stable isotope and trace element composition as well as the flowstone petrography are mainly controlled by the variable drip water discharge controlling the water film thickness and water residence time on the flowstone surface and consequently the intensity of co2 degassing kinetic isotope enrichment and concomitant calcite precipitation drill core pfu6 provides an isotope record of the last ca 3000 years at near annual resolution a distinct phase of low c and o isotope values interpreted as increased discharge and hence higher meteoric precipitation occurred from ca 300 to 140 a b2k second half of the little ice age and another wet interval occurred around 700 a corresponding to reported medieval glacier advances the roman warm period was also dominated by relatively wet conditions although significant decadal variability prevailed increased precipitation further characterized the intervals from ca 2480 to 2430 and 2950 to 2770 a dry conditions persisted during the medieval climate anomaly although this trend towards reduced precipitation started earlier the highest c isotope values of the last 2 ka are recorded around 750 a and another dry phase is centred at 1480 a this new record shows that inter annual to decadal oscillations are a dominant mode of variation during the last 3 ka in the alps copyright 2011 john wiley sons ltd

stalagmite evidence for the precise timing of north atlantic cold events during the early last glacial evidence of millennial scale cold events following the last interglacial are well preserved in north atlantic marine cores greenland ice and pollen records from europe however their timing was previously undetermined by radiometric dating we report the first precise radiometric ages for two such events c23 105 1 0 9 ka to 102 6 0 8 ka and c24 112 0 0 8 ka and 108 8 1 0 ka based on stable carbon and oxygen isotope measurements on a stalagmite from italy cc28 in addition to providing new information on the duration of these events in southern europe the age data provide invaluable tuning points for the melisey i c24 and montaigu c23 pollen zones identified in western europe the former event is of particular significance because it represents the end of the eemian interglacial forest phase in western europe the new age data will also allow fine tuning of the timing and duration of greenland stadial 24 equivalent to c23 in the north greenland ice core project ice core and via a common gasage chronology tuning of the vostok and epica european project for ice coring in antarctica ice cores

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

applications of stalagmite laminae to paleoclimate reconstructions comparison with dendrochronology climatology abstract laminated stalagmites observed in either ultra violet or visible light or recognized via trace elements are now widely recognized as a common deposition form annually laminated stalagmites should be expected in caves which have an overlying climate that has a strong seasonality similar climate zones to where trees grow with distinct annual rings continuous laminated stalagmite chronologies up to several thousand years should be expected where some mixing of stored water occurs such stalagmites can be used to reconstruct climate particularly through variations in lamina width such climate records would be relatively damped by mixing of event water with stored groundwater constraining the amount of high frequency climate signals contained in the stalagmite but relatively long continuous lamina sequences permit the preservation of low frequency centennial scale climate signals this contrasts with numerous tree ring climate records which are frequently limited in preserving multi centennial trends due to the necessary removal of age related noise from relatively short tree segments laminated stalagmites and tree rings should therefore to some degree provide complementary climate information appropriate methods for compiling stalagmite layer chronologies and climatologies are presented

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

investigation of the stable isotope fractionation in speleothems with laboratory experiments many speleothems show evidence for calcite precipitation under disequilibrium conditions to improve the understanding of these kinetic processes several laboratory experiments were performed to study the fractionation of stable oxygen and carbon isotopes during the precipitation of calcite carbonate was precipitated under controlled conditions from both a body of standing water beaker experiments and a solution flowing along a channel channel experiments at a relative humidity of 100 slow degassing of co2 simulated by the beaker experiments results in 18o values in equilibrium with the solution in contrast the 13c values show a significant enrichment inversely proportional to the height of the solution in the beakers fast degassing of co2 simulated by the channel experiments showed an enrichment of both 13c and 18o and a slope of 13c 18o of 1 4 0 6 these results represent experimental evidence for the hendy effect which is manifested in i a progressive increase in 18o and 13c away from the growth axis and ii a positive correlation between 18o and 13c along a single growth layer of a stalagmite

uranium series chronology and environmental applications of speleothems an increasing number of scientists recognize the value of speleothems1 as often extremely well preserved archives of information about past climate vegetation hydrology sea level nuclide migration water rock interaction landscape evolution tectonics and human action well constrained data are required to document past changes reconstruct past patterns and predict future responses of the earth system at a wide range of spatial and temporal scales speleothems are particularly useful in this regard because they can be found in many locations of the globe sampled at high resolution and reliably dated using high precision uranium series techniques speleothems are bodies of mineral material formed in caves as the result of chemical precipitation from groundwater flowing or dripping in a cave most speleothems are composed of calcite formed by slow degassing of co2 from supersaturated groundwater but aragonite and gypsum forms are also common particularly near cave entrances where evaporative effects are important a host of different speleothem types decorate the walls ceilings and floors of caves and their mineralogy and morphology is a function of fluid flow and chemistry of waters feeding a particular location as well as the ambient conditions temperature chemistry light in the air or water filled void subaerial forms include the familiar stalagmites stalactites draperies flowstones subaqueous forms include rimstone pools rafts mammillary calcite wall coatings and dog tooth spar for an extensive review of the types of speleothem that have been observed see hill and forti 1997 speleothems are used in a multitude of ways to explore past environmental conditions perhaps the most fundamental of which is their very presence or absence deposition of speleothems relies on sufficient water supply and soil co2 to enable dissolution and transport of reactants in the vadose zone to underlying caves in arid or glacial times conditions may not have been favorable for speleothem formation

north atlantic current and european environments during the declining stage of the last interglacial this paper provides a tentative reconstruction of environmental shifts in europe associated with changes of the north atlantic current and related meridional sea surface temperature sst gradients during most of the eemian interglacial ca 126 115 ka the north atlantic current extended far north into the nordic seas and european environments were comparable to those of the holocene however ca 115 ka an sst drop in the nordic seas marked a southward displacement of the north atlantic current this hydrographic shift was associated with substantial cooling in northern europe and drier conditions in the mediterranean region the polar timberline retreated southward from 69 n in northernmost scandinavia to 52 n in central europe and thermophilous deciduous trees became extinct north of the 48th parallel woodlands persisted in southern europe for another 5 k y well into marine isotope substage 5d these conditions indicate steep vegetation and climate gradients at the inception of the last glacial

multi isotopic age assessment of dirty speleothem calcite an example from altamira cave spain the dating of dirty speleothem calcite of late pleistocene or holocene age can be problematic this is notably the case with the 14 c method due to uncertainties in the initial 14 c activity of the cave co2 and withth e 230 th 234 u method due to either low u contents in the authigenic calcite and or to the presence of heterogeneous detrital particles containing high concentrations of u and thseries isotopes frequently out of secular equilibrium in this study of a b60 cm thick flowstone sealing archaeological remains of the magdalenian period in the altamira cave nw spain we used a combination of isotopic approaches and analytical techniques to confront dating methods and finally tried to validate chronological interpretations based on stable isotope paleoclimate constraints u series data indicate the presence of a relatively important and heterogeneous detrital fraction resulting in 232 th 230 th mass ratios generally too high 0 1 0 25 10 6 to allow precise tims measurements mc icp ms measurements provided more reliable results and allowed the calculation of 230 th 234 u isochron ages of 11 870 8 ka in the upper part of the flowstone and of b22 ka in the lower part of it in view of the calibrated 14 c ages of these layers b13 and b15 ka bp respectively the isochron age of the lower unit of the flowstone seems erroneous suggesting the presence of an isotopically heterogeneous contaminating fraction in this layer 226 ra 230 thratio measurements indicate near secular equilibrium conditions seriate stable isotope measurements indicate calcite precipitation in isotopic equilibrium with ambient waters they suggest that flowstone deposition ended at the very onset of the younger dryas this transition seems to have occurred here at 11 870 8 72s ka based on th u isochron and 10 770 08 71s uncalibrated 14 c kiloyears the 14 c activity for the cave co2 seems to have been near that of atmospheric co2 during the precipitation interval it is concluded that the 14 c data provide here relatively reliable ages in spite of the fact that they partly fall into a period characterized by 14 c plateau effects but that other isotopic data revealed essential in validating them

annual trace element cycles in calcite aragonite speleothems evidence of drought in the western mediterranean 1200 1100 yr bp each of two calcitic stalagmites from grotte de clamouse herault southern france displays a discrete aragonite layer dated at around 1100 yr bp the layer of fanning aragonite ray crystals is immediately preceded by calcite with mg and sr compositions that are uniquely high for the past 3 kyr trace element compositions close to the boundary between original aragonite and calcite are consistent with quasi equilibrium partitioning of trace elements between the phases study of modern dripwaters demonstrates that pronounced covariation of mg ca and sr ca ratios in dripwater occurs owing to large amounts of calcite precipitation upflow of the drips that fed the stalagmites trace element to ca ratios are enhanced during seasonally dry periods ion microprobe data demonstrate a pronounced covariation of trace elements including mg and sr in calcite and sr u and ba in aragonite the mean peak spacing is close to the long term mean of annual growth rates determined by differences in u series ages and so the trace element peaks are interpreted as annual the trace element chemistry of the stalagmites on annual to inter annual scales thus directly reflects the amounts of prior calcite precipitation interpreted as an index of aridity the longer term context is a multi decadal period of aridity 1200 1100 yr bp possibly correlated with an analogous episode in central america the arid period culminated in the nucleation of aragonite but within a decade was followed by a return to precursor conditions copyright 2005 john wiley sons ltd

lgm and late glacial fluctuations in the eastern alps abstract studies of glacier development in the eastern alps around the last glacial maximum lgm for more than a hundred years have created a reasonably well based knowledge of glacier extent sedimentation and palaeoclimate as well as chronology this was obtained from broad and detailed mapping palynological investigations and radiocarbon dating despite a very cold climate between 31 and 21 ka bp topographical constraints meant that glacier extent was limited to tributary valleys of the main trenches until about 24 ka bp then rapid ice build up in the main longitudinal valleys led to extended ice streams and to piedmont glaciers in the foreland this build up virtually ended at ca 21 ka bp according to radiocarbon dates obtained from organic matter embedded in the outwash and periglacial gravels niederterrasse the lgm possibly lasted 3000 4000 years and shows a short maximalstand and a more prolonged hochstand both connected with outwash deposits the ice decay was apparently very fast and the glaciers vanished from the longitudinal valleys probably within some hundreds of years this retreat was interrupted by two short oscillations of active glaciers in contact with huge masses of inactive ice occupying the main valley floors before these became totally ice free these events at the beginning of the oldest dryas ca 16 ka bp were followed by a distinct glacier readvance gschnitz marked by end moraines and outwash fans according to some radiocarbon dates this occurred around 14 ka bp during the bolling interstade the valleys became almost ice free the next two glacier readvances daun and egesen were limited to cirques and the higher parts of the valleys and are dated to the older and younger dryas stades respectively

climatic controls on frost cracking and implications for the evolution of bedrock landscapes 1 in mountainous landscapes the role of periglacial processes in producing sediment is poorly defined despite evidence of abundant talus slopes ice growth in rock has long been recognized as an efficient erosion mechanism but the effects have not been readily applied to landscape evolution in response to tectonic and climatic forcing here we quantify how and where ice driven mechanical erosion occurs in cold bedrock dominated landscapes using a simple one dimensional numerical heat flow model in our model ice grows by water migration to colder regions in shallow rock by the reduction in chemical potential associated with intermolecular forces between ice and mineral surfaces a process called segregation ice growth the depth and intensity of frost cracking is primarily dependent on mean annual temperature mat with positive mat sites characterized by intense cracking in the top meter of the rock mass and a maximum frost penetration of 4 m in contrast negative mat areas have less intense cracking that primarily occurs at depths between 50 and 800 cm we compare the depth and intensity of frost cracking predicted by our model with measures of the intensity of frost processes determined in three studies the first measured the timing of rockfall in the canadian rockies niagara escarpment and japanese alps the second analyzed scree deposits in the southern alps new zealand and the third documented rockfall frequency in utah these natural examples show that rockfalls tend to nucleate at elevations that coincide with zones of intense frost cracking predicted by our model as such climatic variations associated with interglacial glacial cycles may impart a significant influence on the denudation of mountainous landscapes

cave air control on dripwater geochemistry obir caves austria implications for speleothem deposition in dynamically ventilated caves there are very few process studies that demonstrate the annual variation in cave environments depositing speleothems accordingly we initiated a monitoring program at the obir caves an austrian dripstone cave system characterized by a seasonally changing air flow that results in a predictable pattern of high pco2 during summer and low pco2 in winter although similar seasonal changes in soil pco2 occur they are not directly connected with the changes in the subsurface since the dripwaters are fed from a well mixed source showing little seasonal variation cold season flushing by relatively co2 poor air enhances degassing of co2 in the cave and leads to a high degree of supersaturation of dripwater with regard to calcite forced calcite deposition during the cold season also gives rise to a pronounced pattern of synchronous seasonal variations in electrical conductivity alkalinity ph ca and 13cdic which parallel variations recorded in 13ccave air chemical components unaffected by calcite precipitation e g d 18o sio2 so4 lack a seasonal signal attesting to a long residence in the karst aquifer modeling shows that degassing of co2 from seepage waters results in kinetically enhanced c isotopic fractionation which contrasts with the equilibrium degassing shown from the soreq cave in israel the obir caves may serve as a case example of a dripstone cave whose seepage waters and speleothems show intra annual geochemical variability that is primarily due to chemical modification of the groundwater by a dynamic bidirectional subsurface air circulation

high precision constraints on timing of alpine warm periods during the middle to late pleistocene using speleothem growth periods a long standing problem in the reconstruction of warm climate periods during the late quaternary is the difficulty of determining absolute ages for undisturbed terrestrial climate archives speleothems offer an important source of information about the timing and duration of middle and late pleistocene warm phases a flowstone from the high elevation spannagel cave zillertal alps austria provides a new absolutely dated climate record which includes the most prominent warm phases between 260 and 50 ka before present new data from the penultimate interglacial improve our knowledge about the timing and progression of warm periods in the alps corresponding to marine isotope stages 7 and 8 speleothem growth phases were identified from 261 to 249 from 236 to 229 and from 200 to 192 ka an early onset of the last interglacial is corroborated by a growth phase commencing at 136 7f2 8 ka and the youngest section of the flowstone provides further evidence for an alpine climate during time intervals corresponding to marine isotope stages 5a and 3 sufficiently warm to allow speleothems to grow the high resolution stable isotope profile taken along the growth axis of the flowstone provides information about the hydrological conditions during the growth phases d 2005 elsevier b v all rights reserved

trans alkaline magmatism in the serrinha pedro velho complex borborema province ne brazil and its correlations with the magmatism in eastern nigeria abstract the sol nea complex 572 8 ma comprises various intrusions that total 200 km 2 it cuts palaeoproterozoic migmatized orthogneisses of the serrinha pedro velho complex which is part of the sao jose do campestre massif north tectonic domain of the borborema province ne brazil it is a post collisional intrusion constituted of coarse grained biotite amphibole monzogranites fine grained leucogranites and diorites major trace and rare earth elements data used to constrain the origin and nature of these rocks indicate that the monzogranites display chemical features of weakly peraluminous ferro potassic trans alkaline granitoids similar to coeval occurrences described in eastern nigerian sm nd data together with the whole rock geochemical data suggest that i the monzogranites were generated by partial melting of tonalitic gneiss from the lower crust leaving behind a granulitic residue ii the diorites originated by partial melting of an enriched lithospheric mantle iii the evolution of the sol nea complex involved magma mixing between the monzogranites and diorites k feldspar and amphibole fractionation appear to have occurred during the evolution of the monzogranites leucogranites constituting an elliptical shaped intrusion 80 km 2 the dona ines pluton are intruded to the north of the sol nea complex they also occur as small intrusions cross cutting the border of the sol nea complex geochemical and isotopic data suggest that the leucogranites were generated by melting of crustal palaeoproterozoic rocks rb sr data gave an age of 544 16 ma trans alkaline magmatism is associated with ductile brittle deformation in the serrinha pedro velho complex of the sao jose do campestre massif this event follows the peak of an extensional related high temperature metamorphism upper amphibolite to granulite facies with estimated age of 578 to 574 ma if a pre gondwana reconstruction is considered this event is seen to extend to the african side of gondwana in eastern nigeria