human resilience to lateglacial climate and environmental change in the scheldt basin nw belgium recent palaeoenvironmental analyses in the scheldt basin in nw belgium have identified significant hydrological and vegetation changes between greenland interstadial 1b gi 1b and greenland stadial 1 gs 1 younger dryas yd that enable us to develop hypotheses to explain the radical changes in land use and lithic technology observed between the federmesser and post federmesser occupation of the region the highly productive lacustrine environments of the lower scheldt basin during the allerod enabled relatively high population packing by federmesser groups exploiting the region within a residential mobility system federmesser assemblages indicate a flexible lithic technology centered on the production of unstandardized blades and flakes that were intensively backed to shape various tool forms the destabilization of these landscapes in the scheldt basin between gi 1b and gs 1 yd and the ensuing cold of the yd changed the composition of important secondary biomass from less mobile ungulate species to seasonally mobile reindeer populations human populations were resilient to these changes by developing a highly standardized micro blade technology and microlithic toolkit

geochemistry genesis and health implications of fluoriferous groundwaters in the upper regions of ghana the most appropriate and widely used source of drinking water for the populations of the upper regions of ghana is groundwater in general groundwater quality is acceptable except for some parts of the bolgatanga and bongo districts where there are occurrences of elevated levels of natural groundwater fluoride concentrations of groundwater fluoride in excess of the world health organization who maximum guideline value 1 5 mg l in the bongo area have been known since 1978 however the effect of fluoride on people ingesting the water did not receive public and medical attention until october 1993 when health personnel were asked to investigate the cause of stained teeth in school children the investigation established that 62 of the total population of school children in the bongo area had dental fluorosis against this background a study was initiated to understand the geochemistry genesis and distribution of fluoride in relation to the geology of the area groundwater fluoride in the upper regions ranges from 0 11 to 4 60 ppm with the highest concentrations associated with the fluorine enriched bongo coarse grained hornblende granite and syenite suite the source of groundwater fluoride within the bongo granitoids is dissolution of the mineral fluorite and dissolution of and anion exchange with micaceous minerals and their clay products applying the who recommended guideline values for fluoride in drinking water reveals that 49 of wells in the area deliver water below the optimum level of 0 5 mg l f these populations are thus prone to dental caries twenty eight percent of the wells fall within the optimum interval for good dental health 0 5 1 5 mg l f twenty three percent of the wells have concentrations above the recommended maximum guideline limit of 1 5 mg l f this population is susceptible to dental and possibly skeletal fluorosis climatic conditions of the area suggest that the individual water consumption is in the order of 3 to 4 l which is higher than the who estimate of 2 l adult day in addition dietary intake for the upper region population is probably higher than who baseline values 0 2 0 5 mg day this implies that a much higher population is susceptible to developing dental and skeletal fluorosis than originally suspected geochemical symbol plot maps help geochemists understand factors controlling the distribution and uptake of fluoride in the upper regions but they are of minimal value to health officials responsible for planning epidemiological studies and dental health education programs in the region by casting fluoride data into contoured geochemical health risk maps using intake interval guidelines more closely aligned to regional climatic and dietary conditions health officals can better judge the impacts regional and population based of fluoride on segments of the population such as various sex and age groups

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

multi proxy speleothem record of climate instability during the early last interglacial in southern turkey abstract a stalagmite from dim cave in southern turkey contains a climate record documenting rapid and significant changes in amounts of precipitation between 132 ka and 128 ka during the penultimate glacial interglacial transition some u th dates have been compromised by carbonate dissolution but rigorous selection and tuning to 18o records from other speleothems has generated a robust age model growth rate was initially very slow but a rapid increase at 129 ka was accompanied by strong negative trends in 18o and 13c a combination implying the onset of much wetter conditions isotopic values at 129 ka suggest that groundwater recharge rates and biogenic activity in the soil zone exceeded those of the early holocene a significant isotopic enrichment event at 128 ka during which there was alternating aragonite and calcite deposition documents a strong drying event with a duration of 200 years a concurrent decrease in 87sr 86sr ratios indicates increased groundwater residence times and the cumulative evidence suggests amounts of rainfall fell from well above to slightly below present day levels similar 18o enrichment events are present in coeval speleothem records from southwest france and the northern alps and these together with pollen evidence from italy greece and the iberian margin of drier conditions at this time imply that a climate anomaly extended across the northern mediterranean borderlands the timing duration and structure of this episode are consistent with marine evidence of strong north atlantic cooling early in the last interglacial and there is a resemblance to the holocene 8 2 ka event recorded globally in many proxy climate archives

between warm and cold impact of the younger dryas on human behavior in central europe abstract following a thorough review of high resolution environmental archives this paper aims at discriminating the factors determining the heterogeneous repercussion of the lateglacial younger dryas in central europe when examining the archaeological implications of human adaptation to the subsequent changes in the natural environment two divergent biotic regions are of special interest the north european plain and adjacent areas and the alpine foothills and surrounding mountain ranges in these regions two different archaeological technocomplexes traditions are found the tanged point complex and the curve backed point groups considering the distribution of the archaeological sites witnessing changes in the material culture and subsistence pattern the intensity of the environmental changes caused by the younger dryas is a decisive element settlement discontinuity during the younger dryas is questioned moreover the potential existence of established social networks between the two regions expressed by comparable developments such as microlithization is considered finally the authors assess whether the younger dryas acted as an accelerator or a brake in the process of regional diversification prior to the early mesolithic

start of the last interglacial period at 135 ka evidence from a high alpine speleothem a detailed study of growth periods of a flowstone from spannagel cave in the zillertal alps austria at 2500 m above sea level a site highly sensitive to climate changes offers unprecedented new insights into pleistocene climate change in central europe flowstone sample spa 52 has a high u content to 116 ppm analyses of this sample reveal that episodes of calcite deposition started at 204 3 ka 135 1 2 ka and 122 ka suggesting that at these times the mean air temperature at this high alpine site was within 1 5 c of the present day condition the beginning of growth at 135 ka corresponds to the ending of the last glaciation and is concordant with a midpoint age for the penultimate deglaciation at 135 2 5 ka as deduced from the absolutely dated oxygen isotope curve in sediments from the bahamas as well as with recent coral evidence from barbados indicating a high sea level already by 135 8 0 8 ka this set of data supports evidence against northern hemisphere forcing of termination ii because the insolation maximum is at 127 ka

pleistocene deposits in pierre saint martin cave french pyrenees abstract pleistocene deposits in alpine pierre saint martin cave are preserved in an abandoned river gallery the deposits 300 m long and 25 m high are composed of a lower unit of fallen blocks overlain by debris flows a main unit of laminated clay and a series of river terraces inset into these units the lower and main units are each overlain by speleothems the lower unit represents a cold period probably isotope stage 10 corroded speleothems above it have given u th ages greater than 300 000 330 000 yr b p the main unit with carbonate rich varves devoid of pollen represents a glaciation that occurred before 225 000 yr b p and probably correlates with stage 8 even though such a glaciation has not been previously recognized in the pyrenees the river terraces covered by many noncorroded speleothems probably formed during stage 7 u th ages between 194 000 and 211 000 225 000 yr b p subsequent sinking of an underground river protected the deposits from erosion

pleistocene holocene transition in benelux in benelux belgium the netherlands and luxembourg considerable progress in late glacial and early postglacial archaeological and environmental research has been made during the last decade a substantial part of this paper discusses new evidence on the chronology of the industries which occupied the southern part of benelux dating the occupations from the sandy north is still problematic long after the glacial maximum during which the area remained uninhabited the south of benelux was visited by magdalenian hunter gatherers while hamburgian settlements were present in the north the significance of the continental creswellian is debated during the allerod interstadial federmesser groups occupied most of the area abandoning it with the onset of the younger dryas the presence of the ahrensburgian during that stadial may have been punctuated new elements were introduced and were maintained during the development of the preboreal early mesolithic which eventually colonised the entire region throughout this sequence changes in material culture and related subsistence activities are evident in view of the major problems concerning the quality of the chrono ecological data this paper can only suggest provisional explanations in terms of human reactions to changing environmental conditions

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

high precision u th dating of the rock paintings at mt huashan guangxi southern china the rock art and the associated natural scenery at 38 sites located in the zuojiang river valley in the southwest of guangxi zhuang autonomous region southern china were inscribed recently on unesco s world heritage list the painted panel at the site of mt huashan is probably the largest known rock art panel in the world consisting of approximately 1900 identifiable figures and occupying an area of approximately 8000 m 2 to determine a precise age on the rock art at mt huashan 56 secondary carbonate layers above and below the paintings were studied for their mineralogy oxygen and carbon isotopic compositions and dated by the 230 th u method the 230 th u dating results demonstrate that ages of the rock paintings can be bracketed between 1856 16 and 1728 41yr bp corresponding to the middle to the end of the eastern han dynasty ad 25 to 220 the results imply that the rock painting practices at mt huashan probably lasted more than a century and the zuojiang rock art is younger than that at baiyunwan and cangyuan in yunnan province by 1 to 10 centuries

multi scale variability of the asian monsoon recorded in an annually banded stalagmite during the neoglacial from qixing cave southwestern china abstract solar forcing of the asian summer monsoon asm and the embedded feedback mechanism remain highly controversial in this study interannual scale asm variability from 3 58 to 2 28 ka bp is reconstructed based on the 18 o record of an annually laminated stalagmite from qixing cave in southwestern china the cave 18 o record agrees well with a record of solar activity on the centennial scale during the whole time series furthermore statistical analysis of singular spectrum and wavelet spectrum shows a significant cycle of 60 years one of the solar activity cycles the two lines of evidence have consolidated the solar impact on a centennial decadal time scale of asm variability timing and structure of the 2 8 ka event detected in various archives at a global scale have been well determined in our 18 o record with a high precision time scale established by absolute 230 th dating and annual layer counting we observed an asymmetrical pattern of the event i e a gradual transition at the onset with a rapid end which can be interpreted as a far field effect of changing thermohaline circulations in the north atlantic we further demonstrate a striking inverse correlation between the asm and the indonesian australian summer monsoon iasm on the centennial scale including three dominant asm depression events that are related to periods of weak solar activity the evidence we present here supports that ocean atmosphere interactions amplified the solar signal and caused abrupt cooling events in widespread areas during the holocene

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

oxygen and carbon isotopic systematics of aragonite speleothems and water in furong cave chongqing china abstract to understand oxygen and carbon stable isotopic characteristics of aragonite stalagmites and evaluate their applicability to paleoclimate the isotopic compositions of active and fossil aragonite speleothems and water samples from an in situ multi year october 2005 july 2010 monitoring program in furong cave located in chongqing of china have been examined the observations during october 2005 june 2007 show that the meteoric water is well mixed in the overlying 300 500 m bedrock aquifer reflected by relatively constant 18o 0 11 0 14 1 of drip waters in the cave which represents the annual status of rainfall water active cave aragonite speleothems are at oxygen isotopic equilibrium with drip water and their 18o values capture the surface water oxygen isotopic signal aragonite to calcite transformation since the last glaciation is not noticeable in furong stalagmites our multi year field experiment approves that aragonite stalagmite 18o records in this cave are suitable for paleoclimate reconstruction with high u 0 5 7 2 ppm and low th 20 1270 ppt the furong aragonite stalagmites provide very precise chronology as good as 20s yrs 2 of the climatic variations since the last deglaciation the synchroneity of chinese stalagmite 18o records at the transition into the bolling allerod t ba and the younger dryas from furong hulu and dongge caves supports the fidelity of the reconstructed east asian monsoon evolution however the furong record shows that the cold older dryas od occurred at 14 0 thousand years ago agreeing with greenland ice core 18o records but 200 yrs younger than that in the hulu record the od age discrepancy between chinese caves can be attributable to different regionally climatic environmental conditions or chronological uncertainty of stalagmite proxy records which is limited by changes in growth rate and subsampling intervals in absolute dating seasonal dissolved inorganic carbon 13c variations of 2 3 in the drip water and 5 7 in the pool and spring waters are likely attributed to variable degrees of co2 degassing in winter and summer the variable 13c values of active deposits from 11 to 0 could be caused by kinetically mediated co2 degassing processes the complicated nature of pre deposition kinetic isotopic fractionation processes for carbon isotopes in speleothems at furong cave require further study before they can be interpreted in a paleoclimatic or paleoenvironmental context

aragonite calcite relationships in speleothems grotte de clamouse france environment fabrics and carbonate geochemistry abstract in grotte de clamouse france aragonite forms in a variety of crystal habits whose properties reflect the conditions of formation prolonged degassing and evaporation yield needle aragonite which is more enriched in 18o and 13c than aragonite ray crystals which form near isotopic equilibrium at present aragonite ray crystals form at the tops of stalagmites at very low discharge 0 00035 ml min and when fluid mg ca ratio is 1 1 temperature and evaporation do not seem to have a significant role in their formation the presence of aragonite in stalagmites should be indicative of a decrease in drip rate related to either dry climate conditions or local hydrology fossil aragonite was in part replaced by calcite in a time frame 13c signal and u content and preserved aragonite relicts up to 16 weight the isotope signal of different aragonite habits may reflect conditions of formation rather than climate parameters the real extent of aragonite to calcite transformation may be underestimated when replacement calcite inherits both textural and chemical properties of the precursor

uranium thorium dating of stalagmites applied to study the quaternary of the pyrenees france the example of the gouffre de la pierre saint martin abstract the existence of a radioactive disequilibrium between the decay products of 238 u in continental carbonates particularly the speleothems has been used as a geochronometer for many years the importance of this method is that it covers ages ranging from several thousands to 0 35 ma a period that is difficult to cover by other dating methods in the gouffre de la pierre saint martin the aranzadi gallery reveals an exceptional sedimentary sequence two successive units the first with pebbles and the second composed of a thick carbonated clay series are cut by a succession of river terraces on which speleothems occur the dates obtained from the speleothems cover a period ranging essentially from 211 to 173 ka ago located in the isotopic 18 o dating stages nos 7 and 6 this sequence of erosion and sedimentation corresponds to an important climatic improvement in the pyrenees this example emphasizes in a morpho structural context the power of this technique in studying the quaternary where there are very little data

the impact of diagenesis on high precision upb dating of ancient carbonates an example from the late permian of new mexico we have applied upb trace element and sr isotopic analyses to subsamples of a single specimen of the capitan formation from the permian reef complex of new mexico with the goal of calibrating the late permian time scale and understanding the factors that set and later alter the initial u pb ratio and pb isotopic composition of the limestone the data indicate a limestone upb isochron age of 249 8 4 7 ma 2 and a pbpb age of 249 18 ma in addition with values 238u 204pb ranging up to 4200 among the highest ever recorded for a limestone we also obtain precise single sample 206pb 238u 207pb 235u and 207pb 206pb ages indicating averages of 250 2 3 2 ma 250 0 2 8 ma and 256 3 3 5 ma respectively comparison of the average pb u age of 250 3 ma for the latest guadalupian with published radiometric constraints for the late permian suggests preservation of essentially the depositional age trace element and sr isotopic analyses highlight four samples that preserve a chemical signature expected for primary marine aragonite including high sr 3000 g g high u 2900 ng g low initial pb 26 g g and 87sr 86sr 0 7073 as well as the lower u and higher pb mg and fe expected for a diagenetically altered carbonate these data clearly delineate the diagenetic alteration of the limestone and allow us to demonstrate the critical importance of diagenesis in controlling the spread in values primarily through the expulsion of u but with some incorporation of pb the high are simply a function of preservation of original carbonate chemistry and not of u scavenging by fe oxyhydroxides or phosphates although it has long been suspected that limestone upb and pbpb isochron ages reflect the timing of early diagenesis as opposed to a strictly depositional age this is the first study in which this is conclusively demonstrated to be the case the upb data also suggest a late stage neogene alteration that disturbed the system mainly via the redistribution of u intriguingly the four samples that best retain their primary marine aragonitic geochemistry also best maintained a closed upb system most of the subsamples with comparably high values but clearly altered trace element compositions showed upb systematics indicating late disturbance unfortunately it is not yet possible to determine which processes are responsible for this late stage alteration and it is unclear exactly how to avoid such alteration in future work

effect of aragonite to calcite transformation on the geochemistry and dating accuracy of speleothems an example from castanar cave spain aragonite speleothems are increasingly being used as high resolution climate proxies however aragonite is unstable and susceptible to diagenetic transformation into calcite leading to mineralogical textural and geochemical alterations that have not been fully investigated to provide some insights to these modifications this study combines stable isotope geochemistry and u series dating with petrological observations and empa elemental analyses to characterize a stalagmite from castanar cave caceres spain that shows primary aragonite diagenetically altered and with reverse ages the diagenetic processes include recrystallization to calcite micritization and dissolution characterization and interpretation of the chemistry and nature of the waters from which the aragonite precipitated and of the ones that subsequently formed the calcite indicates that both polymorphs formed from the same fluids these fluids hydrochemically evolved from an aragonite mode to a calcite mode along a diagenetic path within the sample the results show that during transformation the system stayed close in one of the stages and open in the other with the same textural result reverse ages are found either in the recrystallized areas or in the primary aragonite caused by two different u remobilization mechanisms u leaching due to flowing waters on the surface and u loss during the transformation process these results highlight the complex behavior of speleothems during diagenesis and the impact on the geochemical information of the primary and secondary phases and thus the importance of petrological and geochemical characterization of speleothems for paleoclimatic studies

dating the trollesgave site and the bromme culture chronological fix points for the lateglacial settlement of southern scandinavia abstract the bromme culture belongs to the lateglacial the period when people settled in the recently deglaciated southern scandinavia until now there have been only a few imprecise fix points relating to the chronological position of this archaeological culture this situation can now be improved with the aid of research results from a bromme culture settlement at trollesgave in se denmark using pollen and plant macrofossil data lateglacial lacustrine deposits containing waste material from the settlement can be assigned to the end of the climatically mild allerod period a series of 14 c dates establishes the age of the settlement as c 10 826 49 14 c years bp 12 871 12 590 cal yr bp by correlation with climate data from the greenland ice cores the occupation can be assigned to the early part of the cold climatic zone gs 1 thus demonstrating that the global ice core climate zones are not absolutely synchronous with the regional division into biozones

uranium isotope fractionation during coprecipitation with aragonite and calcite abstract natural variations in 238u 235u of marine calcium carbonates might provide a useful way of constraining redox conditions of ancient environments in order to evaluate the reliability of this proxy we conducted aragonite and calcite coprecipitation experiments at ph 7 5 and 8 5 to study possible u isotope fractionation during incorporation into these minerals small but significant u isotope fractionation was observed in aragonite experiments at ph 8 5 with heavier u isotopes preferentially enriched in the solid phase 238u 235u of dissolved u in these experiments can be fit by rayleigh fractionation curves with fractionation factors of 1 00007 0 00002 0 00003 1 00005 0 00001 and 1 00003 0 00001 in contrast no resolvable u isotope fractionation was observed in an aragonite experiment at ph 7 5 or in calcite experiments at either ph equilibrium isotope fractionation among different aqueous u species is the most likely explanation for these findings certain charged u species are preferentially incorporated into calcium carbonate relative to the uncharged u species ca2uo2 co3 3 aq which we hypothesize has a lighter equilibrium u isotope composition than most of the charged species according to this hypothesis the magnitude of u isotope fractionation should scale with the fraction of dissolved u that is present as ca2uo2 co3 3 aq this expectation is confirmed by equilibrium speciation modeling of our experiments theoretical calculation of the u isotope fractionation factors between different u species could further test this hypothesis and our proposed fractionation mechanism these findings suggest that u isotope variations in ancient carbonates could be controlled by changes in the aqueous speciation of seawater u particularly changes in seawater ph p co 2 ca2 or mg2 concentrations in general these effects are likely to be small

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

geochemical appraisal of fluoride contamination of groundwater in the nayagarh district of orissa india the occurrence of high concentrations of fluoride in groundwater 1 5 mg l in the villages of singhpur and sagaragan in the nayagarh district of orissa and its relation with the fluoride rich hot spring water 10 mg l located nearby have been studied the composition of the hot spring water is very comparable to the other thermal waters of the world thermodynamic considerations show that more than 65 of the groundwater and hot spring water samples are oversaturated with calcite and only four samples are oversaturated with fluorite fluoride concentration shows a positive relation to sodium bicarbonate and ph and a negative relation to calcium and magnesium in fluoride rich groundwater and hot spring water principal component analysis shows that the fluoride rich groundwater was produced due to a mixing of hot spring water with the surrounding groundwater studies of the saturation index of fluorite with log electrical conductivity also indicate mixing of hot spring water with the surrounding groundwater the spatial distribution of fluoride in groundwater follows the topography of the area

hunter gatherer responses to the changing environment of the moervaart palaeolake nw belgium during the late glacial and early holocene abstract this paper presents new geo archaeological perspectives on the late glacial and early holocene human occupation around a large palaeolake the moervaart palaeolake 25 km 2 intensive fieldwork using invasive and non invasive survey techniques combined with modelling of the palaeotopography and palaeogroundwater and multi proxy palaeoecological analyses have resulted in a detailed reconstruction of the landscape during the final palaeolithic and early mesolithic occupation of the area a major shift in the occupation from the federmesser culture to the early mesolithic was contemporaneous with a sudden and drastic change in the palaeohydrology of the area between ca 13 300 and 13 000 cal bp end of allerod which coincided with a short but abrupt cooling event known as the intra allerod cold period iacp gi 1b it is assumed that this event triggered the sudden drying up of the moervaart palaeolake and surrounding ponds which until then had provided federmesser hunter gatherers with extensive and fertile grounds for hunting gathering and drinking water the population decline which followed this hydrological event was reinforced by the prevailing cold and harsh conditions of the younger dryas and probably lasted until the pre boreal hunter gatherers returned to the area in the boreal now settling along the proximal floodplain regions of a meandering channel which was connected with the southern scheldt river

the precambrian of sri lanka a historical review early studies of the geology of sri lanka lasted from the beginning of the century until 1935 the modern phase began in the forties whereas intensive studies of the precambrian rocks took place in the last ten years the term vijayan gneiss first used for the gneisses around colombo was changed in 1947 to vijayan series for all rocks outside the central khondalite charnockite belt the latter was named the highland series in 1961 and the vijayan series was subdivided into an eastern and a western component and the name was altered to vijayan complex in 1978 in 1959 a southwestern group was recognized and in 1935 the kadugannawa gneiss was named at present there is a general agreement that the following nomenclature should be used by all workers on the precambrian of sri lanka highland complex hc formerly highland series and southwestern group an intimate association of interbanded ortho and paragneisses including pelitic gneiss metaquartzite marble and charnockitic gneiss which forms the broad belt of rocks extending from northeast to southwest through the central highlands of the island outliers of hc rocks tectonic klippen are found in the vijayan complex at kataragama and maligawila vijayan complex vc formerly eastern vijayan complex consisting of migmatites granitic gneisses granitoids and scattered metasediments and occurring in the east and south of the hc wanni complex wc formerly western vijayan complex consisting of migmatites granitic gneisses charnockitic gneisses minor metasediments and granitoids lying west of the hc kadugannawa complex kc partly the former kadugannawa gneiss for the hornblende and biotite hornblende gneisses within the elongate synformal basins arenas around kandy in the early sixties it was noted that the highland series rocks had been subjected to granulite facies metamorphism and the vijayan series rocks to amphibolite facies metamorphism charnockitic rocks in the highland series showed the characteristics of metamorphic rocks recently near peak metamorphic conditions in the hc were established at 770 900 c and 5 kbar in the west wc to 9 kbar in the east hc with a pronounced regional gradient in palaeopressure relict inclusions of staurolite and kyanite in garnet of hc pelitic gneisses have been shown to document a late stage of a prograde metamorphic p t path a retrograde p t path with coronitic assemblages of retrograde mineral phases like andalusite has also been recorded outliers of hc rocks in the vc are klippen thrust over the vc parts of kc have been interpreted as a metamorphosed layered basic complex in the late seventies three phases of deformation were recognized in the hc presently four phases are known to occur an early view was that the highland series was younger than the vijayan series the former sediments having been laid down on a vijayan floor the hc is now known to be older than the vc the boundary between them being a thrust contact the exact position and nature of the hc wc boundary however is still to be resolved recent geochronological data suggest that 1 hc sedimentation as well as igneous activity in the form of basic lava flows basic sills and dykes took place 2 0 ga ago 2 intrusion of the earliest granitoids into the hc took place 1 8 to 1 94 ga ago 3 orthogneisses of the wc were intruded between 0 67 and 1 1 ga ago 4 orthogneisses of the vc were intruded 1030 to 1040 ma ago and 5 high grade regional metamorphism of the hc vc and wc took place between 455 and 610 ma ago

mineralogical and colour changes of quartz sandstones by heat seven german and three hungarian monumental sandstones have been tested in laboratory conditions to analyse the effect of heat the studied quartz sandstones have a wide range of cements and grain sizes including silica carbonate clay and ferrous mineral cemented varieties of fine medium to coarse grained types cylindrical specimens were heated up to 150 300 450 600 750 and 900 c in an oven the mineralogical and textural changes were recorded and compared by using microscopy xrd dta dtg and sem colours and colour differences a b l values were also measured and evaluated colour changes are related to mineral transformations the most intense colour change is caused by the oxidation of iron bearing minerals to hematite that takes place up to 900 c when temperature increases the green glauconite becomes brownish while the chlorite changes to yellowish at first the colour of burnt sandstone is not a direct indicator of burning temperature since there are sandstones in which the burnt specimens are lighter and less reddish than the natural ones porosity increase is related to micro cracking at grain boundaries above 600 c and within the grains at and above 750 c and mineral transformations the clay mineral structure collapses at different temperatures kaolinite up to 600 c chlorite above 600 c and leads to a slight increase in porosity the most drastic change is observed in calcite cemented sandstones where the carbonate structure collapses at 750 c and cao appears at 900 c subsequently it is transformed to portlandite due to absorption of water vapour from the air this leads to the disintegration of sandstone at room temperature a few days after the heat shock

a window into africa s past hydroclimates the sisal_v1 database contribution africa spans the hemispheres from temperate region to temperate region and has a long history of hominin evolution although the number of quaternary palaeoclimatic records from the continent is increasing much of the history of spatial and temporal climatic variability is still debated speleothems as archives of terrestrial hydroclimate variability can help reveal this history here we review the progress made to date with a focus on the first version of the speleothem isotopes synthesis and analysis sisal database the geology of africa has limited development of large karst regions to four areas along the northern coast bordering the mediterranean eastern africa and the horn of africa southwestern africa and southern africa exploitation of the speleothem palaeoclimate archives in these regions is uneven with long histories of research e g in south africa but large areas with no investigations such as west africa consequently the evidence of past climate change reviewed here is irregularly sampled in both time and space nevertheless we show evidence of migration of the monsoon belt with enhanced rainfall during interglacials observed in northeast africa southern arabia and the northern part of southern africa evidence from eastern africa indicates significant decadal and centennial scale rainfall variability in northwestern and southern africa precession and eccentricity influence speleothem growth largely through changing synoptic storm activity

relationships between colour and diagenesis in the aragonite calcite speleothems in basajaun etxea cave spain abstract basajaun etxea cave north spain contains a wide morphological and colour variety of speleothems most of them are composed of aragonite but calcite speleothems are also found their most common colour is white but there are also pink green and turquoise speleothems in different areas of the cave mg rich dissolution waters from the cave s crystalline dolostone and magnesite host rock favour aragonite precipitation and drive important diagenetic changes in this paper we will discuss how diagenesis modifies speleothem texture mineralogy and geochemistry causing significant changes in the colour we also discuss how speleothems that have undergone diagenesis may also be useful indictors of paleoclimatic conditions our work shows that diagenesis changes the colour of the speleothems because of the mobility of the chromophore elements during this process along with this elemental alteration comes the loss of the primary isotopic signals of speleothems detailed petrological studies of speleothems should precede their analysis for palaeoclimatic reconstruction so that influence of areas affected by diagenesis can be eliminated in addition diagenetic signals also contain valuable information on the changes of the waters within the cave and the overall evolution of speleothems and the cave itself

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

major ion signatures for identification of geochemical reactions responsible for release of fluoride from geogenic sources to groundwater and associated risk in vaniyar river basin dharmapuri district tamil nadu india fluoride is a common constituent in most of the rocks and the release of fluoride into groundwater is the major problem in several parts of the world the present study was carried out with the objective of identifying sources and mechanism of release of fluoride from the rocks and its impact on human health in vaniyar river basin dharmapuri district tamil nadu groundwater samples were collected from 44 wells once in 2 months from june 2011 to august 2014 and analyzed for major cations and anions using an ion chromatograph the possible reasons for the increased concentration of fluoride in groundwater of the area were investigated by taking into account of the agricultural practises and the major rock types in the area the observed order of the dominance of cations in groundwater in the study area is na ca2 mg2 k and that of anions is cl hco3 so42 co3 f the fluoride concentration in groundwater of this region ranges from 0 15 to 6 14 mg l out of 569 samples analysed fluoride concentration exceeded the maximum permissible limit of the drinking water standards of bis 1 5 mg l in 396 samples many people living in this area are suffering from dental and skeletal fluorosis due to prolonged use of fluoride rich groundwater for drinking concentration of fluoride in groundwater is relatively low in wells located in charnockite region whereas the concentration of fluoride in groundwater is high in the deep wells in regions comprising of epidote hornblende biotite gneiss the major source of fluoride in groundwater in the area is due to leaching of fluoride bearing minerals fluoride ions from biotite and hornblende minerals leach into the groundwater and contribute high fluoride concentration in this region the concentration of fluoride in groundwater increases when the water level is deep indicating higher release of fluoride from greater depth the geochemical reactions that control the release of fluoride from fluoride bearing minerals such as biotite and hornblende into groundwater were identified removal of high concentration of fluoride from drinking water is necessary in this region and measures should be taken to supply water after removal of fluoride for the betterment of the livelihood in the area

a lateglacial archaeological site in the far north west of europe at rubha port an t seilich isle of islay western scotland ahrensburgian style artefacts absolute dating and geoarchaeology the exact pattern process and timing of the human re colonization of northern europe after the end of the last ice age remain controversial recent research has provided increasingly early dates for at least pioneer explorations of latitudes above 54 n in many regions yet the far north west of the european landmass scotland has remained an unexplained exception to this pattern although the recently described hamburgian artefacts from howburn and an assemblage belonging to the arch backed point complex from kilmelfort cave have established at least a sporadic human presence during earlier stages of the lateglacial interstadial we currently lack evidence for younger dryas greenland stadial 1 gs 1 activity other than rare stray finds that have been claimed to be of ahrensburgian affiliation but are difficult to interpret in isolation we here report the discovery of chipped stone artefacts with technological and typological characteristics similar to those of the continental ahrensburgian at a locality in western scotland a preliminary analysis of associated tephra pollen and phytoliths along with microstratigraphic analysis suggest the artefacts represent one or more episodes of human activity that fall within the second half of gs 1 and the preboreal period 2015 the authors journal of quaternary science published by john wiley sons ltd

orbital to millennial scale climate variability during marine isotope stages 5 to 3 in northeast iberia abstract the climate during the last glacial cycle was characterized by abrupt millennial scale changes superimposed on long term orbital control this study examines this climate variability for northeast iberia for the time interval 118 9 to 36 9 kyr using a multi proxy approach 18o 13c and mg ca applied to a stalagmite that covers this period continuously during marine isotope stage mis 5 and 4 18o is controlled by orbital pacing whereby more humid conditions prevailed during minima in boreal summer precession in contrast during mis 3 18o lags precession and co varies with 13c 0 53 p value

east asian summer monsoon variations in the past 12 5 ka high resolution delta o 18 record from a precisely dated aragonite stalagmite in central china due to possible aragonite to calcite transformation resulting in alteration in isotopic signatures and a bias in age dating aragonite speleothems are often excluded from paleoclimatic archives however aragonite stalagmites contain ppm level uranium content making them much easier to date achieving higher age dating precisions than calcite stalagmites in this regard provided aragonite to calcite transformation did not occur aragonite stalagmites are potentially well suited for holocene climate research given their climate proxies can be placed into a better constrained chronological framework in this paper we present high precision u th dates and o isotopic time series for a 82 cm long continuous growth aragonite stalagmite lh2 from lianhua cave hunan province china and discuss east asian summer monsoon easm variability for the last 12 5 ka bp before present the u th dated delta o 18 sequence with a mean 16 year resolution and the growth rate pattern of lh2 show that easm experienced a strengthening stage a strong stage and a weakening stage during the last 12 5 ka during the yd 12 5 11 5 ka bp heavy delta o 18 values and low growth rate indicate a weak monsoon period during the preboreal from similar to 11 5 to 10 6 ka bp delta o 18 values decreased dramatically similar to 1 94 parts per thousand reflecting abrupt strengthening of the monsoon from 10 6 to 4 2 ka bp the record is characterized by the lightest delta o 18 values and high growth rates suggesting a strong monsoon period the summer monsoon weakened substantially after 4 2 ka bp as inferred from gradually increasing delta o 18 values and decreasing growth rate overall the intensity of the easm is regulated by summer insolation at 30 degrees n during the last 12 5 ka although oxygen isotope fractionation is different between aragonite h2o and calcite h2o because of rayleigh fractionation law the overall temporal pattern of delta o 18 values from aragonite stalagmite lh2 is concordant with other high resolution holocene calcite stalagmite records from south china the comparison among these records shows that the holocene optimum was synchronous across asian continental region influenced by the easm and indian summer monsoon ism lasting from similar to 10 6 to 4 2 ka bp as reflected by consistently lighter delta 18 ovalues among all these records regardless of their latitudinal difference these records do not support previously reported asynchronism between easm and ism in details the long term delta o 18 trend in lh2 is punctuated by a number of centennial fluctuations for instance two weak monsoon events occurred at 9232 57 yr bp and 8137 21 yr bp correlating in time with cooling events in greenland ice cores the latest weak monsoon event centered at 302 8 yr bp which is related to the little ice age lia in addition the monsoon intensity derived from our record also shows a strong connection with latitudinal migration of the inter tropical convergence zone itcz as recorded in the cariaco basin sediments spectral analysis of delta o 18 values shows that significant peaks match with solar periodicities of 208 yr de vries cycle 86 yr gleissberg cycle or related to delta c 14 production suggesting shorter term monsoon variations are forced by solar radiation overall our study suggests that the delta o 18 record in the aragonite stalagmite is highly consistent with those derived from calcite stalagmites suggesting that aragonite stalagmites are suitable for palaeoclimate reconstruction especially for the holocene period as aragonite calcite transformation has not occurred c 2013 elsevier ltd all rights reserved

factors controlling fluoride contents of groundwater in north central and northwestern sri lanka chemical characterization has been made of groundwater bodies at 294 locations in four village districts in north central and northwestern sri lanka with special focus on fluorine contamination high fluoride contents in groundwater are becoming a major problem in the dry zone of sri lanka and dental fluorosis and renal failures are widespread field measurements of temperature ph and electrical conductivity were made during sampling chemical analyses of the water samples were later made using atomic absorption spectroscopy spectrophotometry and titration fluoride concentrations in the study area vary from 0 01 to 4 34 mg l and depend on ph and the concentrations of na ca and hco3 basement rocks including hornblende biotite gneiss biotite gneiss and granitic gneiss seem to have contributed to the anomalous concentrations of fluoride in the groundwater longer residence time in aquifers within fractured crystalline bedrocks may enhance fluoride levels in the groundwater in these areas in addition elevated fluoride concentrations in shallow groundwater in intensive agricultural areas appear to be related to the leaching of fluoride from soils due to successive irrigation

speleothems and pine trees as sensitive indicators of environmental pollution a case study of the effect of uranium ore mining in hungary abstract four decades of u ore production in hungary provides an opportunity to study the possible environmental effects of mining the study reveals significant changes in chemical composition of a stalagmite cave deposit the good fit between u content changes in the studied deposit and the u ore production rate support the assumption of the relationship with mining activity an independent chemoenviromental archive living pine pinus sylvestis trees were also investigated data on pine tree cores collected from the same region show different levels of pollution cu zn mn u after the 1950s and 1960s linked to the opening of mines and subsequent dust fallout around the site elevated concentrations of detritally derived elements si al th coupled with a rise in u concentration and change in 234 u values of the stalagmite suggest increasing amounts of mine derived dust from 1 to 3 km distance that settled and washed into the karst system the combined usage of different proxies not only provides historic records for the anthropogenic impact in the environment but also allows the timing of u concentration increases within the stalagmite and the identification of elemental behavior from the pollution this study shows that complementary geochemical archives such as stalagmites and tree rings used together can enhance understanding of past environmental contamination

a sealed flint knapping site from the younger dryas in the scheldt valley belgium bridging the gap in human occupation at the pleistocene holocene transition in w europe based on the evidence of a recently excavated sealed site situated at ruien rosalinde in the belgian scheldt valley the response of hunter gatherers to changing climate at the transition from the temperate allerod to the cold younger dryas is discussed radiocarbon dated to the end of the allerod or the very beginning of the younger dryas the site of ruien provides the earliest evidence of a refined lithic technology characterized by the use of a soft stone hammer and the production of straight and regular blade let s from intensively prepared cores with two opposite platforms and sharp striking angles in the course of the younger dryas and early pre boreal this knapping method will become standard all over europe from the tanged point technocomplex in the north to the epi laborian in the south it contrasts sharply with the knapping style of previous lithic traditions such as the late federmesser azilian and bromme technocomplexes which was much less elaborated and mainly oriented towards the knapping of short irregular blades with a hard stone hammer this apparently abrupt technological change was also accompanied by increased raw material procurement networks extending over up to 250 km and a marked microlithisation of the hunting equipment finally the site of ruien is also important as it demonstrates the limited archaeological visibility of younger dryas sites explaining the scarcity of such sites within western europe

comments on anatomy of a late quaternary carbonate island constraints on timing and magnitude of sea level fluctuations west caicos turks and caicos islands bwi by kerans et al quat sci rev 205 2019 193 223 abstract we comment on interpretations of the evolution of late pleistocene geology on west caicos island caicos platform b w i by kerans et al 2019 which omits our documentation of the interrelationship of carbonate facies in outcrop and in boreholes dravis and wanless 2017 we further disagree with their geochronological dating assumptions results that are the basis for interpreting late quaternary sea level fluctuations

controls on the genesis of some high fluoride groundwaters in india india has an increasing incidence of fluorosis dental and skeletal with some 62 million people at risk high fluoride groundwaters are present especially in the hard rock areas south of the ganges valley and in the arid north western part of the country the phenomenon is related to groundwater with residual alkalinity ca2 hco3 fluoride concentrations are governed by adsorption equilibria and by fluorite solubility evapotranspiration leads to a precipitation of calcite a lowering of ca activity and increase in na ca ratios and this allows an increase in f levels in southern india mg seems to be controlled by dolomite while sepiolite and palygorskite are mg sinks in rajasthan but may then release f under alkaline conditions the latter two minerals are probably also important sources and sinks for f in the hydroxy positions the increase in the extent of sodic soils as a result of irrigation is a contributing factor to the increasing incidence of fluorosis remedial measures including addition of gypsum and rainwater harvesting are needed even in areas where the sodicity does not cause structural problems in the soil

fluoride concentrations in a crystalline bedrock aquifer marathon county wisconsin water samples from 2 789 private water supply wells in marathon county wisconsin reveal that fluoride concentrations in the crystalline bedrock range from 0 01 to 7 60 mg l with 0 6 of the values exceeding the environmental protection agency s epa s maximum contaminant level of 4 mg l and 8 6 exceeding the epa s secondary maximum contaminant level of 2 0 mg l roughly a quarter of the wells contain dissolve fluoride within the range considered optimal for human health between 0 5 and 1 5 mg l whereas 63 3 fall below 0 5 mg l consistent with studies conducted in other regions felsic rocks have significantly higher fluoride concentrations than mafic and metasedimentary rocks syenites yield the most fluoriferous groundwaters but the highest median concentration occurs in a sodium plagioclase granite a relationship between plagioclase composition and fluoride concentrations suggests that dissolved fluoride levels are controlled by fluorite solubility and that higher fluoride concentrations are found in soft sodium rich groundwater

strontium heterogeneity and speciation in coral aragonite implications for the strontium paleothermometer sea surface temperatures ssts have been inferred previously from the sr ca ratios of coral aragonite however microanalytical studies have indicated that sr in some coral skeletons is more heterogeneously distributed than expected from sst data strontium may exist in two skeletal phases as sr substituted for ca in aragonite and as separate srco3 strontianite domains variations in the size quantity or both of these domains may account for small scale sr heterogeneity here we use synchrotron x ray fluorescence to map sr ca variations in a porites lobata skeleton at a 5 m scale variations are large and unrelated to changes in local seawater temperature or composition selected area extended x ray absorption fine structure exafs spectroscopy of low and high sr areas indicates that sr is present as a substitute ion in aragonite i e domains of sr carbonate strontianite are absent or in minor abundance variations in strontianite abundance are not responsible for the sr ca fluctuations observed in this sample the sr microdistribution is systematic and appears to correlate with the crystalline fabric of the coral skeleton suggesting sr heterogeneity may reflect nonequilibrium calcification processes nonequilibrium incorporation of sr complicates the interpretation of sr ca ratios in terms of sst particularly in attempts to extend the temporal resolution of the technique the micro exafs technique may prove to be valuable allowing the selection of coral microvolumes for sr ca measurement where strontium is incorporated in a known structural environment

stalagmite from the austrian alps reveals dansgaard oeschger events during isotope stage 3 implications for the absolute chronology of greenland ice cores a mass spectrometric uranium series dated stalagmite from the central alps of austria provides unprecedented new insights into high altitude climate change during the peak of isotope stage 3 the stalagmite formed continuously between 57 and 46 kyr before present a series of hendy tests demonstrates that the outer parts of the sample show a progressive increase of both stable c and o isotope values no such covariant increase was detected within the axial zone this in conjunction with other observations suggests that the continuous stable oxygen isotope profile obtained from the axial zone of the stalagmite largely reflects the unaltered isotopic composition of the cave drip water the n 18 o record shows events of high n 18 o values that correlate remarkably with interstadials 15 a and b 14 and 12 identified in the greenland ice cores interstadial 15b started rapidly at 55 6 kyr and lasted v300 yr only interstadial 15a peaked 54 9 kyr ago and was even of shorter duration v100 yr and interstadial 14 commenced 54 2 kyr ago and lasted v3000 yr this stalagmite thus represents one of the first terrestrial archives outside the high latitudes which record precisely dated dansgaard oeschger d o events during isotope stage 3 provided that rapid d o warmings occurred synchronously in greenland and the european alps the new data provide an independent tool to improve the grip and gisp2 chronologies 2002 elsevier science b v all rights reserved

late pleistocene intensification technologies in northern china intensification technologies used in late pleistocene northern china include microblades milling stones and pottery all of which have been implicated in development of agriculture in northern china perhaps influenced by the harsh climate of the younger dryas this paper examines the adaptive function of these technologies in the context of late pleistocene climate and environment it is proposed that microlithic technology was a tool of mobile foragers focused on hunting and the initial use of pottery was probably connected to bone grease production only milling stones were initially a plant oriented intensification technology but their sparse episodic appearance in the late pleistocene did not lead to persistent intensification involved in the development of agriculture it was only after the younger dryas in the context of improved holocene climate and greater primary productivity that these three technologies converged with changes in mobility to become part of the agricultural revolution in northern china

speleothems travertines and paleoclimates abstract age data for about 660 speleothems and about 140 spring deposited travertines were collected including many unpublished results these data were plotted as histograms and also as error weighted frequency curves on a 350 000 yr scale these plots clearly show periods of increased speleothem travertine growth as well as times of cessation the periods of most frequent speleothem growth were between approximately 130 000 and 90 000 yr ago and since about 15 000 yr ago such periods before 150 000 yr ago however cannot be yet recognized because of a lack of sufficient data and the associated uncertainties of dates in this age range a comparison with the oxygen isotope record of deep sea core v28 238 shows a clear relationship indicating that terrestrial calcite formation is controlled by paleoclimatic fluctuations the evident climatic stimulation of quaternary calcite formation is readily explained geochemically and is substantiated by the obvious difference in speleothem travertine growth as a function of geographic position

high resolution synchrotron x ray fluorescence investigation of calcite coralloid speleothems elemental incorporation and their potential as environmental archives synchrotron high resolution and micro x ray fluorescence elemental mapping of two coeval coralloid speleothems from lamalunga cave italy are complemented with petrographic morphological and microstratigraphic studies the importance of these speleothems relies on their direct and indirect association with a complete neanderthal skeleton altamura man found inside the cave the coralloids grew discontinuously between 64 6 ka and the holocene and reveal exceptionally high concentrations of mg sr and si particularly on convex surfaces where evaporation is more intense the incorporation of trace elements depends on several factors including location shape and geometrical evolution during their growth as well as climate and environmental parameters this resulted in calcite precipitation with sr compositions from 100 to 1200 ppm and an average concentration of 7000 ppm mg an unusually high si content up to 16 is possibly derived from volcanic ash transported as particulate and in solution inside the cave the most common fabrics observed consist of non fluorescent elongated columnar calcite forming clean isopachous bands and fluorescent fibre like crystals associated with laminated lenticular bands high in sr mg and si variability in sr mg and si concentrations appears to induce fabric changes in the coralloids elongation and lattice distortion of the crystals was found to coincide with high mg concentrations the transition from compact elongated to open to fibre like is here interpreted as due to high concentrations of si and sr which are preferentially incorporated in the speleothem at crystal boundaries and intra laminae it is here inferred that coralloid fabric changes and their elemental content potentially record local rainfall variations through time with the clean compact calcite marking high infiltration and open fibre like and micrite fabrics recording dry periods

diagenesis of speleothems and its effect on the accuracy of 230th u ages abstract speleothems can be precisely dated by u series disequilibrium methods one basic assumption of the 230th u dating method is that the system remains closed and u and th isotopes are neither lost nor added after deposition for stalagmites this requirement is usually fulfilled due to their protected environment in caves however undersaturated drip water may lead to diagenesis of speleothem caco3 and altered 230th u ages here we present a detailed petrographic investigation using thin sections and 230th u ages of a stalagmite from the riesenberghohle northern germany which grew during marine isotope stages 5e c and a the occurrence of a mosaic fabric in large parts of the stalagmite in combination with several age inversions is a clear indication for diagenetic alteration we discuss the potential diagenetic processes and quantitatively model their influence on the 230th u ages post depositional u loss leads to increasing 230th 238u activity ratios and thus apparently older ages in contrast post depositional addition of u results in decreased 230th 238u activity ratios and apparently younger ages comparison with our modelling results suggests that diagenesis occurred early after deposition initial and post depositional detrital contamination probably played a minor role for the observed age inversions

uranium uptake history open system behaviour and uranium series ages of fossil tridacna gigas from huon peninsula papua new guinea abstract molluscs incorporate negligible uranium into their skeleton while they are living with any uranium uptake occurring post mortem as such closed system u series dating of molluscs is unlikely to provide reliable age constraints for marine deposits even the application of open system u series modelling is challenging because uranium uptake and loss histories can affect time integrated uranium distributions and are difficult to constrain we investigate the chemical and isotopic distribution of uranium in fossil tridacna gigas giant clams from marine isotope stage mis 5e 128 116 ka and mis 11 424 374 ka reefs at huon peninsula in papua new guinea the large size of the clams enables detailed chemical and isotopic mapping of uranium using la icpms and la mc icpms techniques within each fossil tridacna specimen marked differences in uranium concentrations are observed across the three tridacna growth zones outer inner hinge with the outer and hinge zones being relatively enriched in mis 5e and mis 11 tridacna the outer and hinge zones contain approximately 1 ppm and 5 ppm uranium respectively in addition to uptake of uranium loss of uranium appears prevalent especially in the mis 11 specimens the effect of uranium loss is to elevate measured 230th 238u values with little effect on 234u 238u values closed system age estimates are on average 50 too young for the mis 5e tridacna and 25 too young for the mis 11 tridacna a complex multi stage uptake and loss history is interpreted for the fossil tridacna and we demonstrate that they cannot provide independent reliable geochronological controls on the timing of past reef growth at huon peninsula