recently growing subaqueous flowstones occurrence petrography and growth conditions abstract subaqueous flowstones have been studied in two resurgence caves in slovak karst southern slovakia namely krasnohorska and drienovska caves the flowstones litter streambeds within the distance of several hundred meters upstream from resurgences they form laminated crusts within channels of the underground streams flowing through the caves layers composed of columnar sparry calcite alternate with those composed of microcrystalline calcite the latter are enriched in fine detrital non carbonate components which resulted in crystallization of microcrystalline calcite instead of sparry calcite the growth rate of the studied flowstones reaches 0 96 mg cm 2 day which corresponds to ca 0 3 mm per year seasonal observations conducted between november 2010 and september 2012 reveal that deposition of subaqueous flowstones in the studied caves significantly depends on the local hydrological conditions during the periods of low flow si calc values of underground stream increase and columnar sparry calcite grows conversely during peak flow periods si calc values decrease and subaqueous flowstones are subjected to destruction both by mechanical erosion and corrosion the decreasing discharge just after peak flows causes deposition of fine grained particles which results in precipitation of microcrystalline layers subaqueous flowstones grow in complete darkness and in atmosphere with elevated co 2 content similarly to typical speleothems but they are fed with turbulent stream water similarly to calcareous tufas their growth rate is higher than those of normal flowstones fed with a film of water seeping down it falls within a range of growth rate of calcareous tufas though near the lower limit of this range therefore subaqueous flowstones represent an intermediate link between other speleothems and tufas deposited outside the cave environment

environmental factors controlling the δ13c and δ18o variations of recent fluvial tufas a 12 year record from the monasterio de piedra natural park ne iberian peninsula abstract a 12 year study 2000 2012 of the stable isotopes of recent fluvial tufas has been performed in the monasterio de piedra natural park river piedra ne iberian peninsula an area of mediterranean climate with intense tufa deposition since the pleistocene the biannual monitoring of the tufa calcite 13c and 18o signatures and of the water 18o value has demonstrated a clear seasonal pattern for the tufa calcite oxygen isotope composition with less negative values for cool periods which is consistent with regional temperature oscillations the tufa calcite 13c values only occasionally exhibit a pattern which is inconclusive and opposite to the 18o clear pattern the water 18o signature has a distinct seasonal pattern also opposite to the tufa calcite 18o clear pattern the temperature calculations from the tufa calcite 18o values and average water 18o values agree with the seasonal pattern of measured water temperatures with a mean difference of 2 3 c between the calculated and measured temperatures the anomalous values recorded for both the water and the tufa calcite oxygen isotope composition during a two year period are characterized by smoothing of the seasonal variations of the tufa calcite and by reversal of the water pattern there is also an increase in the differences between the measured and estimated temperatures the detected anomaly is roughly synchronous with a change in the isotopic signature of the regional precipitation 18o values this contribution demonstrates that tufas in this depositional and climatic context are good indicators of seasonal temperature oscillations and that tufas can also record other interannual environmental changes such as variations in the isotopic composition of precipitation these results can be extrapolated to ancient tufa systems developed in similar contexts which would expand the potential of tufas as high resolution records of paleoenvironmental conditions

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

geomagnetic field for 0 3 ka 2 a new series of time varying global models 1 steadily increasing numbers of archeomagnetic and paleomagnetic data for the holocene have allowed development of temporally continuous global spherical harmonic models of the geomagnetic field extending present and historical global descriptions of magnetic field evolution the current work uses various subsets of improved data compilations details of which are given in a companion paper by donadini et al 2009 and minor modifications of standard modeling strategies using temporally and spatially regularized inversion of the data and cubic spline parameterizations for temporal variations to produce five models with enhanced spatial and temporal resolution for 0 3 ka spurious end effects present in earlier models are eliminated by enforcing large scale agreement with the gufm1 historical model for 1650 1990 a d and by extending the model range to accommodate data older than 3 ka age errors are not considered as a contribution to data uncertainties but are included along with data uncertainties in an investigation of statistical uncertainty estimates for the models using parametric bootstrap resampling techniques we find common features but also significant differences among the various models indicating intrinsic uncertainties in global models based on the currently available holocene data model cals3k 3 based on all available archeomagnetic and sediment data without a priori quality selection currently constitutes the best global representation of the past field the new models have slightly higher dipole moments than our previous models virtual axial dipole moments vadms calculated directly from the data are in good agreement with all corresponding model predictions of vadms these are always higher than the spherical harmonic dipole moment indicating the limitations of using vadms as a measure of geomagnetic dipole moments

testing a logic tree approach for archaeoseismology to the ancient city of pinara sw turkey geologists seismologists as well as archaeologists increasingly apply archaeoseismological investigations to study possible natural causes of damage of a site and to assess the regional seismic hazard risks archaeoseismological investigations enable the obtaining of diverse data on past earthquakes and allow for an application of different methods furthermore archaeoseismology provides the opportunity to study past earthquakes in regions where limited instrumental and historical data are available therefore this approach contributes to a regional assessment of seismic hazard the increasing application and importance of archaeoseismology requires a comprehensive and systematic approach the logic tree methodology for archaeoseismology is an evaluation method which offers a standard procedure to identify and evaluate archaeoseismological information and to provide comparable values for seismic hazard assessment this study tests the logic tree methodology for archaeoseismology to pinara to assess the city s potential to have recorded earthquakes and the methodology s value the ancient city of pinara sw turkey 500 bc 900 ad is situated in the esen basin in the southern extremity of the seismically active fethiye burdur fault zone the present seismic quiescence of the esen basin contradicts the geological and historical records which indicate that fault and earthquake activity must have been recurrent with the application of the logic tree approach to pinara geological and archaeoseismological evidence of seismic activity is evaluated in six stages the end solution of the logic tree provides a value between 0 and 1 this archaeological quality factor aqf reflects the reliability and relative significance of pinara for archaeoseismological investigation and seismic hazard assessment respectively pinara s preferred end solution pes1 of 0 06 and the aqf of 0 12 are obtained by the logic tree method and reflect the high probability of recorded palaeoearthquakes in pinara in sum the logic tree for archaeoseismology provides a concept with reliable criteria to assess the earthquake hypothesis in general and the findings suggest the assumed low seismic hazard potential of this area needs serious reconsideration 2011 elsevier ltd and inqua

seasonal patterns of carbon chemistry and isotopes in tufa depositing groundwaters of southwestern japan abstract annually laminated carbonates known as tufas commonly develop in limestone areas and typically record seasonal patterns of oxygen and carbon isotope compositions 18o values are principally controlled by seasonal changes of water temperature whereas 13c values are the result of complex reactions among the gaseous liquid and solid sources of carbon in the system we examined the processes that cause the seasonal patterns of 13c in groundwater systems at three tufa depositing sites in southwestern japan by applying model calculations to geochemical data underground inorganic carbon species are exchanged with gaseous co2 which is mainly introduced to the underground hydrological system by natural atmospheric ventilation and by diffusion of soil air these processes control the seasonal pattern of 13c which is low in summer and high in winter among the three sites we investigated we identified two extreme cases of the degree of carbon exchange between liquid and gaseous phases for the case with high radiocarbon composition 14c and low pco2 there was substantial carbon exchange because of a large contribution of atmospheric co2 and a small water mass for the other extreme case which was characterized by low 14c and high pco2 the contribution of atmospheric co2 was small and the water mass was relatively large our results suggest that at two of the three sites water residence time within the soil profile was longer than 1 year our results also suggested a short residence time less than 1 year of water in the soil profile at the site with the smallest water mass which is consistent with large seasonal amplitude of the springwater temperature variations the 14c value of tufas is closely related to the hydrological conditions in which they are deposited if the initial 14c value of a tufa depositing system is stable 14c chronology can be used to date paleo tufas

early curvilinear fold structures and strain in the moine of the glen garry region inverness shire four regional deformation episodes d1 d4 are recognized in the moine rocks loch eil and glenfinnan divisions of the glen garry area inverness shire nw scotland these episodes fall into two groups early sub recumbent d1 d2 structures and later upright d3 d4 structures d2 structures occur on all scales and appear in a regional sense to be more important than the d1 structures the d1 d2 structures are only preserved in their original disposition where subsequent upright d3 reworking was minimal i e in the region to the e of the loch quoich line and in low strain augen developed in d3 hinge zones to the w of this structure the f2 folds are intensely curvilinear and at many localities f2 hinges lie approximately parallel to the n s trending extension lineation examination of these structures in three dimensions and application of the sanderson 1973 model provides information on the nature and orientation of the regional d2 strain ellipsoid in this part of the moine the d2 xy plane is sub horizontal with the x direction trending approximately n s this is markedly different in orientation from the d3 ellipsoid in this region which being of post glen dessary syenite 456 ma age is demonstrably caledonian the d2 linear fabrics suggest that the direction of tectonic transport was s to n or n to s markedly different from the generally accepted wnw directed movement attributed to caledonian orogenesis these findings are consistent with the proposal that the loch quoich line represents an eastern limit of intense caledonian d3 reworking and that the d1 d2 structures are of precambrian age

temporal and environmental significance of microbial lamination insights from recent fluvial stromatolites in the river piedra spain despite extensive research the environmental and temporal significance of microbial lamination is still ambiguous because of the complexity of the parameters that control its development a 13 year monitored record of modern fast accreting calcite stromatolites mean 14 mm year 1 from artificial substrates installed in rapid flow in the river piedra north east spain allows comparison of the sedimentological attributes of successive six month depositional packages with the known climatic hydrophysical and hydrochemical parameters of the depositional system the stromatolites are formed of dense porous and macrocrystalline composite laminae the dense and porous composite laminae which are composed of two to eight laminae consisting largely of calcified cyanobacteria are characterized by i dense composite laminae up to 15 mm thick mostly with successive dense laminae and minor alternating dense and porous laminae and ii porous composite laminae up to 12 mm thick consisting mainly of porous laminae alternating with thinner dense laminae most of the dense composite laminae formed during the warm periods april to september whereas most of the porous composite laminae developed in the cool periods october to march each dense and porous composite lamina represents up to or slightly longer than six months the alternation of these two types of composite laminae parallels seasonal changes in temperature the dense and porous laminae result from shorter for example intraseasonal variations in temperature insolation and hydrological conditions the macrocrystalline laminae with crystals 100 m long occur isolated and grouped into composite laminae up to 1 7 mm thick their occurrence suggests the absence or poor development of microbial mats over periods of weeks to several months thus stromatolite lamination can record different order periodic and non periodic changes in the magnitude of environmental parameters over a single year these results hold important implications for the temporal and environmental interpretation of lamination in microbial structures

archaeomagnetic results from southern italy and their bearing on geomagnetic secular variation archaeodirectional results from kilns and other baked structures in southern italy are presented they are generally compatible with the much larger data sets from france and bulgaria in particular a summary of all the results associated with the well known eruption of vesuvius that destroyed pompeii n 9 d 355 i 5 8 95 1 5 provides a reliable archaeomagnetic anchor point supporting the french and bulgarian master curves it is extremely well constrained in time and it comprises independent studies carried out in four different countries furthermore it is derived from a diverse set of features agreement amongst which argues strongly against significant perturbations due to magnetic refraction structural disturbance or depositional shallowing in terms of geomagnetic secular variation we interpret the western european archaeomagnetic data summarized here in terms of an open loop caused by westward drift followed by an inclination low spanning the first few centuries ce representing the signal of a static flux pulse that reaches a maximum magnetic moment of a few percent of the earth s main central dipole 2005 elsevier b v all rights reserved

u series dating of the travertine depositing near the rongma hot springs in northern tibet china and its paleoclimatic implication abstract high resolution age data obtained by travertine dating is necessary for the reconstruction of paleoclimate and palaeohydrology near rongma hot springs in northern tibet u series dating of a travertine cone depositing in the study area was used the results show that the u contents of the travertine samples range from 0 298 to 1 363 ppm and the 234 u 238 u is in the rage of 1 475 1 700 indicating that the deposition of travertine near the rongma hot springs is stable and continuous the age of the travertine samples ranges from 11 500 to 4600 a corresponding to the first stage of mis 1 combination of the first stage of mis with the effect of monsoon climate of the indian ocean in the same period implies a warm and humid climate during the deposition of the travertines in the study area the u series age range in the rongma hot springs area is coincident with that of the travertine in southern tibet the age data detected from travertine cone help in understanding the evolution of hydrogeology of the hot spring area high resolution age data must be acquired before travertine can be confidently used as a paleoclimatic archive

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

lacustrine isotopic evidence for multidecadal natural climate variability related to the circumpolar vortex over the northeast united states during the past millennium a pervasive 20 30 yr periodicity is observed in stable oxygen isotope values over the past 1000 yr from varved lacustrine calcite obtained from fayetteville green lake new york correlation analysis between historical oxygen isotope values and winter vortex latitude shows an inverse relationship wherein an expanded vortex is associated with high d 18 ocalcite values and vice versa an expansion of the vortex favors advection of cyclones from the gulf of mexico and the atlantic regions characterized by high d 18 oprecipitation values whereas a contracted vortex favors the development of cross continental storms originating in the pacific which preferentially rain out 18 o as they propagate eastward we hypothesize that changes in the size of the winter vortex every 20 30 yr over the past 1000 yr modify the primary source regions for meteoric precipitation we propose two possible climate forcings to explain our hypothesis an external forcing related to solar variability and an internal forcing related to ocean atmosphere links

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

structural dating of a precambrian pegmatite in moine rocks of northern scotland and its bearing on the status of the morarian orogeny a cross cutting pegmatite emplaced into low grade non migmatitic proterozoic moine metasediments on the western sea board of inverness shire scotland gives rb sr muscovite ages of 746 776 ma which are interpreted as minimum estimates for the age of formation of the pegmatite intrusion followed at least one phase of folding and schistosity production in the country rocks and an early phase of syn kinematic garnet growth correlated with the regional d 2 tectono metamorphic event the pegmatite was folded and suffered considerable grain size reduction under metamorphic conditions during the regional d 3 deformation episode the dilational character and low grade context of the pegmatite show that it was not a product of melting in place during metamorphism of the adjacent moine schists its lack of initial syn kinematic crystallization textures and fabrics together with the absence of evidence that might relate its emplacement to any regional phase of compressive ductile deformation would be compatible with a considerable time lapse between its intrusion and the earlier deformation and metamorphism of the host rocks we have however no direct evidence for the extent of this interval the relationship of the pegmatite to the earlier deformation and metamorphism of the host rocks provides clear evidence for substantial precambrian orogenic activity but the age of this activity whether 9morarian9 and or 9grenvillian9 remains a matter of interpretation

abnormal shallow palaeomagnetic inclinations from the 1950 and 1972 lava flows hawaii summary high precision palaeomagnetic sampling and measurements of 1950 mauna loa lava flows hawaii show as noted by other workers a significantly low inclination compared to the geomagnetic direction expected from available observatory data such shallow inclinations appear related to the unusually high intensity of magnetization of the 1950 basalt resulting in a high magnetic refraction for the lava flows considered other altered palaeomagnetic directions both inclination and declination on kilauea 1972 flows possibly result from displacements during and or after cooling erroneous palaeomagnetic direction imprints do not appear to be the rule

diagenesis or dire genesis the origin of columnar spar in tufa stromatolites of central greece and the role of chironomid larvae two greek pleistocene tufa stromatolites were examined petrographically and with stable isotope geochemistry to determine whether calcite spar is of primary or diagenetic origin the younger ca 100 ka tufa from zemeno primarily is micritic with primary columnar calcite spar restricted to areas immediately above chironomid larval tubes this relationship suggests that chironomid larval feeding behaviour is responsible for the development of zemeno tufa columnar calcite probably involving biological substances smeared onto the tufa surface most micritic crystals are not suitably oriented to allow later post depositional growth resulting in columnar fabrics the older ca 1 ma predominantly sparry tufa from nemea contains some chironomid tubes and organic cyanobacterial filaments preserved in crystal fans but also contains many fabrics found in primary speleothem spar columnar spar here is unlikely to be the result of post depositional crystal growth a comparison of stable isotopic trends between the two tufa deposits suggests that both contain interpretable seasonal trends and implies little or minor post depositional alteration of either tufa consequently there is no basis for the common assumption that sparry tufa fabrics must be of diagenetic origin

ensembles of low degree archeomagnetic field models for the past three millennia abstract we introduce ensembles of time varying archeomagnetic field models consisting of a reference model a mean model and a thousand individual models we present a set of three such ensembles built from archeomagnetic volcanic and sedimentary data sets that cover the past three millennia these ensembles can be used to describe the field at any location from the core surface to the magnetosphere and assess the way uncertainties due to the limited distribution and quality of the data affect any of its component or parameter such as individual gauss coefficients they provide alternative and we argue more complete descriptions of the archeomagnetic field to those provided by previously published archeomagnetic field models being better suited to existing and emerging needs such as those of geomagnetic data assimilation we present the data sets we rely on essentially the same as those used by other recent archeomagnetic field models and describe how errors affecting the data and errors due to non modelled small spatial scales of the field are taken into account we next explain our modeling strategy and motivation for building low degree spherical harmonic degree ensembles of models we carry on a number of end to end simulations to both illustrate the usefulness of such ensembles and point at the type of errors one should expect practical illustrations of what can be done with these three ensembles of models with examples of geomagnetic inferences are also described northern high latitude flux patches for instance appear to be the most robust features of all these patches tend to fluctuate but clearly have some favored locations resulting in the same clear signature with three tongues over northern america europe and asia in the time averaged field at the core mantle boundary similar to what had been found in earlier models inferences about the field behavior in the southern hemisphere are more difficult to draw still some suggestions that the well known present south atlantic reversed patch could have arisen as early as in 1500 a d are found in some of the ensembles we otherwise confirm that most of the current archeomagnetic field model limitations are related to a number of sediment cores identified as producing frequent outliers in the modeling process we provide evidence that such cores are likely affected by timing errors and timing delays between magnetization lock in and sediment deposition that future more advanced treatment should be able to handle all source files for the three ensembles of models together with appropriate matlab applications can be downloaded from http geomag ipgp fr download archeo fm zip

late pleistocene holocene palaeoenvironmental evolution of the anamaza river valley iberian range ne spain multidisciplinary approach on the study of carbonate fluvial systems abstract the uppermost pleistocene and holocene palaeoenvironmental evolution of the anamaza river valley iberian range ne spain is deduced using multidisciplinary approach including stratigraphical mineralogical palynological geochemical geophysical methods and drilling main changes were registered in distinct subenvironments of a carbonate fluvial system including the channelled zone and wetlands in the floodplain tufa barrages dominated although pools also existed geophysical survey and coring reveal tufa build ups and pool facies also in the subsoil lower water temperature and scarce evaporation are deduced for the pleistocene fluvial system that progressively changed through the holocene with more hydrologically closed areas and higher evaporation influence a general aggrading evolution during warm stages related with increasing base level and damming due to fast carbonate precipitation characterised the holocene detrital tufa indicates erosive high energy floods or colder stages when water level would decrease favouring erosion 14 c and 230 th 234 u dating reveal high sedimentation rates and three main discontinuities related with cold episodes younger dryas middle part of the holocene climate optimum and iron age epoch during the uppermost pleistocene tufa growth would be enhanced during warmer episodes as the bolling allerod in the younger dryas scarce vegetation favoured erosion of both slopes and tufa constructions subsequent warmer temperatures during the first part of the holocene favoured vegetated slopes enhanced tufa growing although interrupted in the middle part of the holocene climate optimum and development of wetlands with riparian vegetation in the floodplain where either siliciclastics or detrital tufa incoming alternated with low energy waters stages and mud settling progressive decline in tufa is deduced for the upper holocene but it is not possible to determine whether this and other palaeoenvironmental changes were related either to climate or increasing human activities during the roman and medieval warm periods more oxidizing conditions in the wetlands and increasing erosion prevailed probably conditioned by human activities the pollen record shows for the early holocene development of pinus forest with betula and expansion of deciduous quercus xerophilous and heliophilous grassland subsequent increasing moisture supported open forests with deciduous quercus ulmus corylus and evergreen quercus ilex pistacia species from ca 4000 yrbp a dominant deciduous quercus forest with groves of corylus ulmus acer fagus and taxus expanded and human activities grazing occurred from 1200 yrbp dry grassland expanded due to intensive land use agropastoral activities almost completely deforested plateaus surround the site today with slopes covered by patchy grass with junipers groves and screeds with little soil

effect of in stream physicochemical processes on the seasonal variations in δ13c and δ18o values in laminated travertine deposits in a mountain stream channel abstract travertines are potential archives of continental paleoclimate records of stable carbon and oxygen isotopic composition 13 c and 18 o in laminated travertine deposits from endogene spring waters show regular cyclic patterns which may be due to seasonal change in climate determinants such as temperature and rainfall in this study 13 c and 18 o measurements of three travertine specimens that grew naturally over the eight years 2004 2011 at upstream middle and downstream sites in a canal at baishuitai sw china are presented they exhibit clear seasonal variations that generally correlate with biannual laminations specifically 13 c and 18 o values show significant positive correlation with each other for the three travertine specimens with the correlation coefficients increasing downstream along the canal to reveal the factors governing the seasonal and spatial variations in 13 c and 18 o values newly formed travertines precipitated on plexiglas substrates are also examined both 13 c and 18 o of the substrate travertines are low in the summer rainy season and high in the winter dry season showing a great consistency with the patterns in the natural travertines spatially isotope values increase downstream in both seasons with higher increase rates in winter that are related to removal of larger fractions of dissolved inorganic carbon dic from the solution and stronger kinetic isotopic fractionation in winter due to in stream physicochemical processes including caco 3 precipitation and the associated degassing of co 2 seasonal changes in 13 c and 18 o in the travertines are amplified by two times between the upstream and downstream sites this is opposite to trends for epigene meteogene tufas whose seasonal changes in stable isotope compositions are reduced downstream we suggest in stream physicochemical processes are a potential reason for underestimation of annual temperature ranges that are inferred from epigene tufa 18 o data

high resolution records of rainfall events from clay bands in tufa individual rainfall events are recorded as thin clay bands in annually laminated freshwater carbonate tufa runoff from rainfall events entrains clay that then adheres to the tufa surface a specimen collected from southwest japan exhibits 100 clay bands formed during a 15 yr period from 1988 to 2002 the chronology of the clay bands was determined by using the temperature dependent cycle of oxygen isotope ratios in the carbonate and the clay content was quantified by electron probe microanalysis si x ray strength the obtained si x ray strength curve and actual rainfall record follow a nearly identical pattern the clay content of each band correlates with rainfall amount rainfall of 50 mm week produced sufficient amounts of suspended cave clay to produce clay bands in the tufa because the clay bands survive postdepositional alteration this new method can be applied to ancient tufa deposits and has great potential as a high resolution rainfall record for use in climate studies

speleothem evidence from oman for continental pluvial events during interglacial periods growth periods and stable isotope analyses of speleothems from hoti cave in northern oman provide a record of continental pluvial periods extending back over the past four of earth s glacial interglacial cycles rapid speleothem growth occurred during the early to middle holocene 6 10 5 ka b p 78 82 ka b p 120 135 ka b p 180 200 ka b p and 300 325 ka b p the speleothem calcite deposited during each of these episodes is highly depleted in 18 o compared to modern speleothems the d 18 o values for calcite deposited within pluvial periods generally fall in the range of 24 to 28 relative to the vienna peedee belemnite standard whereas modern speleothems range from 21 to 23 the growth and isotopic records indicate that during peak interglacial periods the limit of the monsoon rainfall was shifted far north of its present location and each pluvial period was coincident with an interglacial stage of the marine oxygen isotope record the association of continental pluvial periods with peak interglacial conditions suggests that glacial boundary conditions and not changes in solar radiation are the primary control on continental wetness on glacial interglacial time scales

origins of elements building travertine and tufa new perspectives provided by isotopic and geochemical tracers fluid rock interaction represents a major process in the formation of calcitic or aragonitic travertine and tufa catt in most cases catt is associated to limestone dissolution somewhere along the hydrogeological pathway however a wide array of other substratum basalts rhyolites carbonatites ultramafics granites dolomites evaporites can act as potential source of elements involved in the formation of catt this study reports on the evaluation of potential geochemical tracers linking catt to their substratum and unravelling the origin of elements a large database was established from available literature data as well as new data acquired in the frame of this study for a set of modern to recent catt ligurian ophiolites italy the chaine des puys limagne graben and paris basin france reunion island indian ocean jebel oust tunisia four most reliable tracing methods are identified 1 13c and 18o cross plot allows distinguishing epigean min 13c 27 2 max 13c 0 9 mean 13c 12 3 for n 314 from hypogean systems min 13c 4 max 13c 11 7 mean 13c 2 87 for n 198 very low 13c values 4 associated to negative 13c values are specifically indicative of an ultramafic source rock 2 barium and strontium cross plot helps to discriminate different groups of source rocks amongst the hypogean catt i source rocks composed of mixed limestones evaporites and dolomites are characterised by low barium 400 ppm contents ii mafic and granitic source rocks are undifferentiated and display similar barium from 15 to 930 ppm and high strontium 200 ppm contents iii the carbonatite group is characterised by its exceptional high barium and strontium values in epigean catt a pure limestone source rock usually relates to very low barium and strontium contents 50 ppm 3 relatively high beryllium content 30 ppm in catt seems to indicate a pure granitoid source 4 high chromium concentrations 20 ppm are systematically documented in modern catt located on an ultramafic substratum the definition of diagnostic compositional fields for actively forming or recently formed catt is influenced by many factors including water composition water temperature dissolved gas composition and concentration biological activity position in the sedimentary body and early diagenesis in addition to substratum lithology however the results of this study illustrate that despite these many factors the combined use of ba sr be cr 13c and 18o may be valuable to discriminate the rock lithology prevailing in the hydrogeological or palaeo hydrogeological reservoir of catt

the april 2007 eruption and the dolomieu crater collapse two major events at piton de la fournaise la reunion island indian ocean abstract after 10 years of high activity and 24 eruptions piton de la fournaise pdf produced on april 2 to may 1 2007 one of its most voluminous and intense eruption since at least one century the eruption focused at 590 m elevation in the grand brule on the south east flank of piton de la fournaise 7 km away from summit it was located close to the southern cliff of the grand brule volcano tectonic collapse the rempart du tremblet and to the nearby village called le tremblet and it highly rattled and incommoded the inhabitants there eleven hours after the beginning of the eruption the lava flows reached the sea and created 0 45 km 2 of new land until the end of eruption in the night of april 5 the rock column beneath dolomieu crater started to collapse with a piston like mechanism into the magma chamber forming within less than 24 h the most recent and well documented caldera we report in this paper the chronology of these two related major events in the recent activity of pdf seen by the scientific networks of the volcanological observatory ovpf ipgp and field observations which allowed to back up the scenario of the caldera formation and to quantify these two exceptional episodes

laminated carbonate deposits in roman aqueducts origin processes and implications carbonate deposits in roman aqueducts of patara and aspendos southern turkey were studied to analyse the nature of their regular layering optical microscopy and electron backscattered diffraction results show an alternation of dense coarsely crystalline translucent laminae composed of bundles and fans of elongate calcite crystals with their c axes parallel to the long axis and porous fine grained laminae with crystals at near random orientation the 18o and 13c data show a strong cyclicity and anti correlation whereby high and low 18o values correspond to dense columnar and porous fine grained laminae respectively geochemical analyses show similar cyclic changes in carbonate composition electron microprobe and laser ablation inductively coupled mass spectrometry analyses show that porous fine grained laminae are enriched in elements associated with detrital material fe mg k al and si whereas the dense columnar laminae are nearly pure calcite the gradient in major and trace element distribution regular changes in crystal type and in oxygen and carbon isotope composition from porous fine grained to dense columnar laminae reflect changes in water chemistry discharge temperature and biological activity because of the strong bimodal cyclicity of the mediterranean climate in southern turkey the observed laminae can be attributed to calcite deposition during the dry porous fine grained and wet season dense columnar respectively this observation implies that with proper geochemical and microstructural control lamination in carbonate deposits in roman aqueducts can be used for relative dating of aqueduct construction and maintenance and to obtain data on external factors that influenced the aqueducts such as palaeoclimate and natural hazards carbonate deposits in roman aqueducts show properties of both flowstone speleothems and riverine fresh water tufa as many aqueducts of nearly identical channel geometry are present in different climate zones and with different source water characteristics they can be used as natural experiment setups to test and improve existing models of how laminated fresh water carbonates record climate on time scales ranging from seasonal to millennial

the role of gypsum and or dolomite dissolution in tufa precipitation lessons from the hydrochemistry of a carbonate sulphate karst system the precipitation of freshwater carbonates tufa along karstic rivers is enhanced by degassing of carbon dioxide co2 downstream of karstic springs however in most karstic springs co2 degassing is not enough to force the precipitation of tufa sediments little is known about the role of dissolution of gypsum or dolomite in the hydrochemistry of these systems and how this affects the formation of tufa deposits here we present a monitoring study conducted over a year in trabaque river spain the river has typical karst hydrological dynamics with water sinking upstream and re emerging downstream of the canyon mixing of calcium magnesium bicarbonate and calcium sulphate waters downstream of the sink enhances the dissolution of carbonates and potentially plays a positive role in the formation of tufa sediments however due to the common ion effect dissolution of dolomite and or gypsum causes precipitation of underground calcite cements as part of the incongruent dissolution of dolomite dedolomitization process which limits the precipitation of tufa sediments current precipitation of tufa is scant compared to previous holocene tufa deposits which likely precipitated from solutions with higher saturation indexes of calcite sicc values than nowadays limited incongruent dissolution of dolomite dedolomitization favours higher sicc values this circumstance occurs when waters with relatively high supersaturation of dolomite and low so42 composition sink in the upper sector of the canyon in such a scenario the process of mixing waters enhances the exclusive dissolution of limestones preventing the precipitation of calcite within the aquifer and favouring the increase of sicc values downstream of the springs such conditions were recorded during periods of high water level of the aquifers and during floods this research shows that the common ion effect caused by the dissolution of gypsum and or dolomite rocks can limit or favour the precipitation of tufa sediments depending on the occurrence or not of incongruent dissolution of dolomite dedolomitization copyright 2016 john wiley sons ltd

origin of annual laminations in tufa deposits southwest japan abstract laminated tufas and a tufa depositing stream in sw japan shirokawa ehime prefecture were studied monthly over a 3 yr period a series of samples from the tufa clearly reveals the pattern of annual laminations the annual layering pattern was primarily controlled by changes in the rate of calcite precipitation as calculated from water chemistry the concentration of dissolved caco 3 which correlates with the precipitation rate was high in summer autumn and low in winter spring owing to changes in the partial pressure of co 2 in underground air regular seasonal changes in underground pco 2 probably resulted from two temperature dependent processes the diffusion of soil co 2 and the ventilation of underground air these changes in addition to water temperature changes altered the precipitation rate which has a clear seasonal pattern especially in the lower stream the seasonal precipitation rate was high in summer autumn and low in winter spring which is consistent with the seasonal lamination pattern seen in the tufas the textures of collected samples show that the laminations consist of densely calcified summer autumn june october laminae and lightly calcified winter spring november may laminae we infer that the increased precipitation rate stimulated thick calcite encrustation on cyanobacterial filaments to produce the dense textures this interpretation is supported by the lowered organic inorganic carbon production ratio in summer autumn seasonal variations in cyanobacterial assemblages are present but do not reflect the seasonal lamination pattern because the relevant processes are temperature dependent the seasonal lamination pattern at shirokawa is thought to generally apply to other laminated tufas deposited in temperate climates however a reversed pattern can result from local and climatic circumstances dense laminae were deposited in winter near the source of the spring at shirokawa because calcite precipitation was high owing to low underground pco 2 in winter reversed patterns reported from northwestern europe were probably influenced by seasonal rainfall which is reflected in hydrological conditions

are light dark coupled laminae in lacustrine shale seasonally controlled a case study using astronomical tuning from 42 2 to 45 4 ma in the dongying depression bohai bay basin eastern china abstract as a typical sedimentary structure in fine grained rocks laminae are widely distributed in shales and mudstones in sedimentary basins the shahejie formation 42 2 45 4 ma formed during the eocene of the paleogene in the dongying depression of china is recognized as a typical area to study lacustrine shale according to the composition of different lamina four types of couplets are identified including carbonate clay couplets carbonate organic couplets clay organic couplets and carbonate clay organic triplets all couplets are composed of light and dark layers a combination of core images microscopic observations mineral compositions geochemical data carbon and oxygen isotopes and strontium isotopes verifies that the laminae are primarily developed in a saline and anoxic or even euxinic environment with a high organic matter om flux through astronomical cycle analysis of the natural gamma ray gr curve from sample site well ny1 the data suggest that the lacustrine shale laminae are formed annually with an average duration of 1 34 yr the formation of laminae is affected by the season which is closely related to the seasonal growth and death of algae during the period of algae growth a large number of light colored carbonate laminae are deposited whereas when the algae dies organic matter accumulates at the bottom of lakes and forms dark organic rich laminae the interbedded and lenticular laminae which are subdivided by layering characteristics are primarily affected by diagenesis in postdepositional processes study of the laminae is helpful in understanding the formation process of lacustrine shale and it provides invaluable sources of information for paleoclimate reconstruction

magma transport and storage at piton de la fournaise la reunion between 1972 and 2007 a review of geophysical and geochemical data abstract since the middle of the 20th century improvement in volcano monitoring techniques has provided large data sets that can be used to evaluate the evolution of magma plumbing systems at piton de la fournaise volcano abundant eruptive activity and a dense monitoring network are especially conducive to such research analysis of the extensive set of geophysical and geochemical data associated with the last 35 years of activity provides new insights into magma transport and storage at piton de la fournaise two periods of frequent eruptions separated by 6 years of inactivity can be distinguished 1972 1992 and 1998 2007 considering these two periods we show evidence of major changes in the shallow plumbing system in 2000 during 1972 1992 and 1998 2000 lava compositions and weak long term eruptive precursors lasting few days to three weeks characterized by no significant summit inflation and about ten volcano tectonic earthquakes per day suggest that eruptions were fed by the progressive drainage of an occasionally recharged shallow magma reservoir geophysical evidence of shallow magma reservoir recharge was only recorded in 1986 and 1998 in contrast from 2000 to 2007 geophysical data highlight the appearance of long term precursors 1 to 5 months of summit inflation and strong seismicity up to one hundred events per day preceding cycles of successive eruptions each cycle of eruptions was characterized by a sequence 3 to 10 months in duration of summit and near summit proximal eruptions and ended with a distal low altitude oceanite olivine abundances 20 vol eruption on the eastern flank of the volcano within each of these eruptive cycles lavas became progressively more magnesian over time the preferential motion of the eastern flank caused by continuous recharging of the shallow reservoir since 2000 would favour the occurrence of distal eruptions towards this flank at the end of a cycle

cyclic variations of uranium concentrations and oxygen isotopes in tufa from the middle miocene barstow formation mojave desert california uranium concentrations of 42 to 169 ppm in fibrous calcite from spring deposited tufa in the middle miocene barstow formation california are among the highest reported for calcite fission track maps of multiple bands of uniformly dull luminescent fibrous calcite show that the concentration of u increases in the outward growth direction of the calcite of each individual band homogeneous dull luminescence in the fibrous calcite indicates no change in redox conditions of the fluid from which the calcite was precipitated it is proposed that the cyclic pattern of increase in u concentration reflects a cyclical change in the u ca ratio in the fluid episodic mixing between ca rich spring water with a low u ca ratio and ca poor saline alkaline lake water with a high u ca ratio could produce the episodes of formation of fibrous calcite with increasing u concentrations the spring water supplies the ca for calcite precipitation and the u concentrations increase with the decreasing fraction of spring water and increasing fraction of lake water these cycles reflect a variable recharge of groundwater into the lake by springs the large variation in u concentrations suggests mixing of 0 to 45 spring water with the lake while the narrow range in 18 o of 6 37 to 6 87 limits the variation of the proportions of spring and lake water to 5

archeomagnetism of piton de la fournaise bearing on volcanic activity at la reunion island and geomagnetic secular variation in southern indian ocean historical and other recent lavas from piton de la fournaise la reunion island are studied using the large sample archeomagnetic method which provides here paleodirections of the earth magnetic field with confidence cones between 0 9 and 2 5 thus offering a precise record of the geomagnetic field and potential dating constraints ages of the lavas are known thanks to historical chronicles from 1708 or 14c dating and their analysis give information about the directional secular variation sv in a region where observatory measurements are scarce and not available before the end of the 19th century for the past 250 yr we find a high value of inclination 50 to 55 with respect to the geographic latitude 21 s connected with a very restricted directional sv conversely the older volcanic units present a larger sv with magnetic inclinations of between 31 and 46 and declinations from 16 w to 10 e these results which are in reasonable agreement with instrumental measurements made on ships in the vicinity of la reunion allow us to infer that undated lavas of the northern part of the caldera emanated from eruptions during the second half of the 1700s other volcanic products e g mare longue flow piton chisny cone and flows and pointe langevin despite their fresh morphology are necessarily older than about 1500 ad further knowledge of the path of the sv in the more distant past and therefore further archeomagnetic dating is hampered by the lack of a precise chronology through radiometric or other similar methods available models of the geomagnetic field during the last millennium which suffer from the scarcity of data in the southern hemisphere are discussed in the light of our results

anatomy of piton de la fournaise volcano la reunion indian ocean the aim of this work is to propose a general model of piton de la fournaise volcano using information from geological and geophysical studies firstly we make a graphical compilation of all available geophysical information along a w e profile secondly we construct a geological section that integrates both the geophysical information and the geological information the lithosphere beneath piton de la fournaise is not significantly flexed and the crust is underlain by an underplating body which might represent the deep magma reservoir for la reunion volcanism piton de la fournaise is a relatively thin volcano lying on a huge volcanic construction attributed mostly to les alizes volcano indeed if the differentiated rocks observed at the bottom of the riviere des remparts are the top of les alizes volcano the interface with piton de la fournaise may be located at about sea level beneath the summit area the endogenous constructions intrusive complexes related to les alizes and piton de la fournaise volcanoes represent a large volume the huge intrusive complex of les alizes volcano probably rests on the top of the oceanic crust and appears to have a buttressing effect for the present eastern volcano tectonic activity of piton de la fournaise the early piton de la fournaise edifice was built around a focus located beneath the plaine des sables area the center subsequently moved 5 6 km eastward to its current location the dense high velocity body beneath the plaines des sables and the western part of the enclos probably corresponds to the hypovolcanic intrusive complex that developed before the volcanic center shifted to its present day position magma reservoirs may have existed and may still exist as illustrated by the march 1998 crisis at the mechanical and density interface between the oceanic crust and the les alizes edifice strong evidence also exists for the presence of a shallower magma reservoir located near sea level beneath the summit the march 1998 pre eruptive seismic pattern location and upward migration seems to be evidence for a transfer of magma between the two reservoirs the dominant structural feature of the central zone is a collapse structure beneath the summit craters above the inferred magma reservoir near sea level the collapsed column constitutes a major mechanical heterogeneity and concentrates most of the seismic intrusive and hydrothermal activity because of its higher permeability and weaker mechanical strength

wet dry seasonal and spatial variations in the δ13c and δ18o values of the modern endogenic travertine at baishuitai yunnan sw china and their paleoclimatic and paleoenvironmental implications abstract seasonal and spatial variations in the 13 c and 18 o values of the modern endogenic thermogene travertine deposited in a calcite depositing canal at baishuitai yunnan sw china were examined to understand their potential for paleoclimatic and paleoenvironmental implications the sampling sites were set in the upstream middle reach and downstream of the canal and the modern endogenic travertine samples were collected semimonthly to measure their 13 c and 18 o values it was found that both 13 c and 18 o values of the endogenic travertine were low in the warm rainy season and high in the cold dry season and correlated with each other the low 18 o values in warm rainy season were mainly related to the higher water temperature and the lower 18 o values of rainwater and the low 13 c values are caused by the dilution effect of overland flow with low 13 c values in the warm rainy season and the reduced co 2 degassing of canal water caused by the dilution effect of the overland flow the linear negative correlation between the travertine 18 o or 13 c values and rainfall amount may be used for paleo rainfall reconstruction if one knows the 18 o or 13 c values of the fossil endogenic travertine at baishuitai though the reconstruction was not straightforward it was also found that there was a progressive downstream increase of the 18 o and 13 c values of the travertine along the canal the former being mainly due to the preferential evaporation of h 2 16 o to the atmosphere and the latter to the preferential release of 12 co 2 to the atmosphere during co 2 degassing however the downstream increase of the travertine 18 o and 13 c values was less intensive in rainy season because of the reduced evaporation and co 2 degassing during the rainy season to conclude the downstream travertine sites could be more favorable for the paleo rainfall reconstruction while the upstream travertine sites are more favorable for the paleo temperature reconstruction so this study demonstrates that endogenic travertine like epigenic meteogene tufa could also be a good candidate for high resolution paleoclimatic and paleoenvironmental reconstruction

archeomagnetic dating in western north america an updated reference curve based on paleomagnetic and archeomagnetic data sets 1 a robust database of paleomagnetic pm and archeomagnetic am data for western north america covering the past 4 millennia is assembled from three data sets 1 published pm data for dated lava flows 2 recently published am data generated by r l dubois and 3 published am data generated by j l eighmy chronologic information for the am data sets has been reassessed and the data points have been assigned to age ranges depending on their archeological contexts we have selected the computer program archeocourbe available from m le goff http www ipgp fr legoff or the auxiliary material see also http earthref org to construct am reference curves and to quantitatively estimate am dates for archeological and geological samples the updated curve provides a more detailed record of prehistoric secular variation for western north america than was previously available and shows a short interval of rapid secular variation sv in the 10th or 11th centuries at near excursional rates similar and coeval features in the hawaiian and to a lesser extent arkansan sv data sets possibly indicate a rapid amplitudinal shift in the regional nondipole field at that time

palaeoenvironmental records in holocene spanish tufas a stable isotope approach in search of reliable climatic archives tufa deposits are potential terrestrial archives of palaeoenvironmental and palaeoclimatic information this study assesses the potential of stable isotopic archives from two closely juxtaposed holocene tufa sites in se spain the ruidera site contains deep water lacustrine micrites and tufas whereas the nearby alcaraz site represents a shallow barrage tufa understanding site characteristics is critical to interpreting the stable isotopic variations these holocene lacustrine micrites have isotopic compositions consistent with modern european lake shore microbial carbonates where the isotopic chemistry is strongly influenced by hydrological and residence time effects all the lacustrine micrite d13c values were influenced by microenvironmental microbial effects to some degree because of these effects stable isotope data from lacustrine microbial micrites and tufas will not normally yield precise information on the isotopic composition of palaeoprecipitation temperature or vegetation composition of an area in contrast holocene tufas that formed in shallow fast flowing riverine settings may contain valuable palaeoclimatic archives the tufa deposits must be largely autochthonous as at alcaraz where in situ reed stem encrustations are present records of relative change in air temperature and changes in the source of airmasses are potentially resolvable in the d18o data these interpretations can be verified by other independent climatic data where chronology is constrained variations in riverine tufa d13c values probably record changes in local vegetation and or soil respiration covariation between d18o and d13c values may be intrinsically linked to climatic factors such as aridity tentative palaeoclimatic interpretations for the middle holocene at alcaraz based on the isotope data suggest warming or increasing influence of mediterranean sourced precipitation between approximately 5000 3000 radiocarbon years bp accompanied by increased aridity these interpretations are consistent with the sparse independent palaeoclimatic data and climate modelling results for the holocene of se spain this study supports the growing evidence that well chosen tufa sites could yield valuable palaeoclimatic information

the sgurr beag slide within moine rocks at loch eilt inverness shire the sgurr beag slide is shown to be a syn to late tectonic movement zone of local f 3 age within a regionally developed five phase deformation sequence it truncates both lithological units and a major f 3 synform and is associated with the intensification of an f 3 crenulation fabric the widespread development of boudinage and the tightening of interlimb angles of major and minor f 3 folds the moine rocks of the glenfinnan and morar divisions on either side of the slide share the same pre sliding history of deformation and metamorphism they both contain minor f 2 folds with strongly developed axial planar mica foliations enhanced in pelitic lithologies by migmatitic segregations together with less abundant minor f 1 folds the slide is refolded by isoclinal major f 4 folds and by major open f 5 folds

la reunion an example of channeled hot spot plume la reunion a large intraplate volcanic system in the mascarene basin indian ocean is widely considered as the expression of a mantle plume or hotspot it lies in a region of the mascarene basin bounded by 2 major transform faults and an extinct rift the bathymetry suggests the presence of a positive topographic anomaly around la reunion we have compared the bathymetry with a theoretical bathymetry based on the thermal subsidence of the oceanic lithosphere as a function of its age a bathymetric anomaly of several hundreds of meters is shown but it is confined to the la reunion zone analogue models have been carried out to explore the deformation resulting from a mantle plume rising beneath a faulted lithosphere they show that the plume and the associated deformation are channeled into the area enclosed by the transform faults and the paleo rift the deformation is virtually nil outside the zone fault bounded zone we have analyzed the surface features and the available gravity and magnetic data in order to find evidence of the deformation predicted by the presence of the bathymetric anomaly and by the analogue models no clear pattern of deformation has been recognized but we demonstrate the complex organization of the oceanic crust in the la reunion zone the fact that the plume head focuses on the restricted area of the zone may amplify the dynamic support of the lithosphere beneath la reunion where not flexure is observed we also suspect that some seamounts near la reunion could correspond to a recent magmatic activity distinct from that of the island the mantle plume lithosphere interaction model presented here is a new to the oceanic domain and it will have to be confirmed by subsequent observations in the la reunion area and possibly in other similar sites on earth

geomagnetic field for 0 3 ka 1 new data sets for global modeling 1 paleomagnetic and archeomagnetic records are used in both regional and global studies of earth s magnetic field we present a description and assessment of five newly compiled data sets also used in the companion paper by korte et al 2009 to produce a series of time varying spherical harmonic models of the geomagnetic field for the last 3000 years data are drawn from our compilation of lake sediment records and from the online database geomagia50v2 the five selections are available from the earthref digital archive at http earthref org cgi bin erda cgi n 944 data are grouped according to the source of material and we conducted separate assessments of reliability for archeomagnetic artifacts and lava flows the arch3k dat data set and for sediments sed3k dat the overall number of data is 55 greater than in previous compilations constrained data sets were selected using different criteria for each group winnowing of archeological data was based on uncertainties supplied by the original data providers the lake sediment data assessment relied on preassigned age uncertainties and one or more of the following comparisons with archeomagnetic data from the same region regional consistency among several lakes and consistency with global archeomagnetic models we discuss relative merits of a larger unconstrained data set or a smaller possibly more reliable one the constrained data sets eliminate a priori up to 35 of the available data in each case and rely on potentially subjective assessments of data quality given the limited data available our analyses indicate that iterative rejection of a small number 1 1 5 of outlying data during global field modeling is a preferable approach specific regional comparisons among the models and data support the conclusion that korte et al s outlier free cals3k 3 model based on all available measurements from sediments and archeological artifacts currently provides the best global representation of the 0 3 ka field the arch3k 1 model provides a better fit to the denser european archeomagnetic data and may be better in that region

oxygen isotope composition of annually banded modern and mid holocene travertine and evidence of paleomonsoon floods grand canyon arizona usa abstract holocene and modern travertine formed in spring fed havasu creek of the grand canyon arizona was studied to determine the factors governing its oxygen isotope composition analysis of substrate grown travertine indicates that calculated calcite formation temperatures compare favorably with measured water temperatures and include silt rich laminae deposited by monsoon driven floods ancient spring pool travertine is dated by u series at 7380 110 yr and consists of 14 travertine silt couplets of probable annual deposition one hundred eighty high resolution 18o analyses of this mid holocene sample average 11 0 pdb the average value for modern travertine is 0 5 lower perhaps because mid holocene temperature was higher or there was proportionally greater summer recharge 18o cyclicity in the mid holocene travertine has average amplitude of 1 9 0 5 pdb slightly less than the inferred modern day annual temperature range of havasu creek the annual temperature range might have been reduced during the 14 yr interval compared to present although other non temperature factors could account for the muted annual variation silt rich laminae within isotopically lower calcite in the modern and mid holocene travertine verifies the seasonal resolution of both samples and suggests that similar temperature precipitation conditions as well as monsoon generated summer floods prevailed in the mid holocene as they do throughout the grand canyon region today

the structural setting and tectonic significance of the glen dessary syenite inverness shire the glen dessary syenite crops out in the steep belt of the northern highland moine it is enclosed within a psammite envelope which was previously assigned to the glenfinnan division but which is here correlated with the psammites of the loch eil division exposed to the e of the loch quoich line three episodes of deformation have been identified in the moine metasediments of the glen dessary area but only the latest d 3 is thought to have deformed the syenite imposing on it a strong steeply plunging mineral lineation the syenite is thought to occupy the core of a large intensely curvilinear d 3 synform the d 3 structures which deform the syenite can be correlated with upright structures which reworked previously flat lying already crystalline rocks recognized at loch quoich upright reworking must be younger than the glen dessary syenite dated by u pb methods at 456 5 ma two hitherto unrecorded small bodies of granitic gneiss similar to the c 1020 ma ardgour gneiss have been identified in psammites of the loch eil division near the w end of loch arkaig their presence suggests that the loch eil division has a grenville history and is part of the 9old moine9

geochemical and hydrological controls on biannual lamination of tufa deposits abstract fluvial tufa deposits in southwest japan commonly develop biannual lamination consisting of dense summer layers and porous winter layers and the clearness of the laminae varies among the sites the laminae have been largely attributed to a seasonally variable inorganic precipitation rate of calcite this rate controlled hypothesis was examined by using quantitative data for calcite packing density cpd and the precipitation rate of calcite pwp rate calculated from water chemistry the results for four tufa depositing sites in sw japan show that a positive correlation between cpd and pwp rate becomes less certain with increasing pwp rate in the temperature realm of sw japan tufas develop regular distinct seasonal change in cpd when deposited in water containing ca values less than 65 mg l which results in a relatively low precipitation rate the cpd of tufa deposits rarely exceeds 65 owing to pore space between fine grained calcite crystals and to porosity derived from decomposed cyanobacteria and other microorganisms by increasing the ca content to more than 65 mg l the cpd often attains an upper limit and becomes insensitive to seasonal changes in the pwp rate therefore seasonal variations in cpd at sites with a higher ca content are unclear as seen in two examples from tropical islands in southern japan and in one locality in a temperate climate the flow rate and microbial density on the tufa surface are subordinate factors with respect to the cpd seasonal changes in these two factors often enhance the porous dense contrast of biannual lamination in sw japan

freshwater phytoherm reefs the role of biofilms and their bearing on marine reef cementation abstract bioconstructions in carbonate rich freshwater environments generally lead to the development of thick autochthonous tufa deposits in rivers systems these large plant dominated freshwater reef frameworks phytoherms are capable of damming the water courses to produce chains of lakes the resulting phytoherms profoundly modify both local environment and sedimentation patterns in their vicinity and provide a wide range of niches for biota subaqueous fringe cements coat all exposed surfaces they bind the ephemeral plant frameworks providing a cement framework and give rigidity to the bioconstructions peloids are intimately associated with the development of these cements and frequently infil intra reef and framework cavities evidence is presented to suggest that both micritic fringe cements and peloids are the product of biological mediation associated with a procaryote microphyte biofilm and the presence of organic detritus the bladed low magnesium calcite fringes which develop subsequently on the micrite fringes and peloids are possibly slower formed inorganic precipitates the close morphological similarities between phytoherm fringe cements and peloids and their marine reef counterparts are considered to be more than coincidental it is argued that procaryote microphyte biofilms are also responsible for micritic precipitates in the shallow photic marine realm with bacterial films possibly carrying the process deep into unlit reef cavities and conduits and deep water lithoherms

the loch quoich line a limit of early palaeozoic crustal reworking in the moine of the northern highlands of scotland the loch quoich line a major structural line at least 60 km in length within the moine of the northern highlands of scotland has hitherto been variously interpreted as a major tectonic dislocation the root zone of a nappe and an unconformity the work reported here was carried out at the type locality of the line and was directed at resolving these ambiguities the lithostratigraphic succession established by sedimentary structures shows that the rocks of the glenfinnan division are older than but are stratigraphically continuous into those of the loch eil division rocks of the loch eil division crop out extensively to the w of the loch quoich line and are not restricted in outcrop to the area e of the line as was previously thought the early d 1 d 2 structures were initially sub horizontal steeply inclined nne trending d 3 structures are weakly developed e of the axial trace of a major fold the beinn beag synform in this area the metasediments remain essentially in their post d 2 gently inclined attitude w of the axial trace of the synform the earlier folds and fabrics were severely reworked into steep attitudes during d 3 producing nne trending zones of 9platy9 rocks which mark regions of severe strain on d 3 fold limbs earlier d 1 d 2 structures are clearly preserved in d 3 hinge zones which mark zones of low d 3 strain it is concluded that the loch quoich line coincides with the axial trace of the beinn beag synform and that it is the eastern limit of severe tectonic reworking probably caledonian over printing early probably precambrian structures recognition of structural and stratigraphic continuity between the glenfinnan and loch eil divisions implies that the loch quoich line cannot be correlated across the great glen fault with the putative unconformity separating the grampian cover and central highland basement divisions in the moine rocks of the central highlands

environmental and depositional controls on laminated freshwater carbonates an example from the roman aqueduct of patara turkey abstract carbonate deposits in aqueducts are a new high resolution data source for environmental changes during the time of the roman empire notably in the fields of palaeoclimate and spring hydrology in order to distinguish environmental effects from those related to depositional setting laminated carbonate deposits were compared along the entire length of an ancient aqueduct channel at patara turkey the carbonate deposits up to 80 mm in thickness are composed of lamina couplets up to 1 mm thick of alternating porous microspar and dense columnar sparite the former formed in the dry warm season and the latter in the wet cool season the presence of biofilms seems to play a role in the development of the porous laminae the relative importance of both lamina types depends also on the location within the aqueduct dense coarse crystalline laminae dominate in steep sections of the aqueduct while porous fine crystalline laminae are mostly found on gentle slopes this is attributed to the flow velocity of the water since fast flow on steep slopes hampers the development of biofilms carbonate microstructures can vary considerably down the line of a specific aqueduct hence multiple sampling is needed along the channel in order to collect specimens suitable for detailed research 18 o profiles show oscillations with increasing amplitude downstream reflecting rising water temperatures in the channel while evaporation plays a minor damping role on these oscillations the periodicity of the 18 o values can be used to recognise annual layering in order to establish the number of years an aqueduct was operating 13 c values are higher in open masonry channel sections than in ceramic pipes probably due to stronger degassing of co 2 in the open channel carbonate deposits in roman aqueducts hold high promises as seasonally resolved archives of hydrology and climate and possibly of earthquakes

wet dry seasonal variations of hydrochemistry and carbonate precipitation rates in a travertine depositing canal at baishuitai yunnan sw china implications for the formation of biannual laminae in travertine and for climatic reconstruction travertine or tufa is a chemical sedimentary deposit that is precipitated from springfed stream water supersaturated with calcite due to co2 degassing liu et al 1995 pentecost 1995 ford and pedley 1996 these deposits have biannual laminations which could provide valuable paleoclimatic and paleoenvironmental information with high resolution liu et al 2006 kano et al 2007 brasier et al 2009 lojen et al 2009

ground penetrating radar evaluation of the internal structure of fluvial tufa deposits devanos anavieja system ne spain an approach to different scales of heterogeneity

three millennia of directional variation of the earth s magnetic field in western europe as revealed by archeological artefacts directional secular variation of the geomagnetic field over the last 2000 years has been defined in western europe from numerous archeomagnetic studies however the number of archeomagnetic results for older periods is much more limited for this reason we present new data obtained from fired archeological structures found in two french sites loupiac and aspiran dated within the first millennium b c latest bronze earliest iron age transition 850 700 b c and iron age 525 475 b c respectively from a compilation of archeomagnetic results from western europe great britain italy and france and northern africa tunisia we propose a directional secular variation curve for western europe that covers the entire first millennium b c this curve exhibits a large clockwise motion with rapid changes during the first half of the millennium while the last four centuries b c are characterized by weak variations

april 2007 collapse of piton de la fournaise a new example of caldera formation collapse calderas are frequent in the evolution of volcanic systems but very few have formed during historical times piton de la fournaise is one of the world s most active basaltic shield volcanoes the caldera collapse which occurred during the april 2007 lateral eruption is one of the few large documented collapse events on this volcano it helps to understand the mode and origin of caldera collapses in basaltic volcanoes field observations gps and seismic data show that the collapse occurred at an early stage of the eruption the cyclic seismic signal suggests a step by step collapse that directly influenced the lateral eruption rate likely the caldera results from the combined effect of i the progressive collapse of the plumbing system above the magma chamber since 2000 and ii the large amount of magma withdrawal during the early stage of the eruption by both a significant intrusion within the edifice and an important emission rate

explosive activity of the summit cone of piton de la fournaise volcano la reunion island a historical and geological review summit explosive activity and collapses that form pit craters and calderas represent major volcanic hazards on a dominantly effusive frequently active volcano like piton de la fournaise only three summit collapse events 1986 2002 2007 have been recorded since the foundation of the piton de la fournaise volcano observatory ovpf in 1979 and two of them 1986 and 2007 were associated with weak phreatic activity at piton de la fournaise the normal explosive activity consists of short lived and mild 20 m high lava fountains which quickly evolve into strombolian activity during the eruptions based on comprehensive literature review and high resolution image analysis of surface outcrops and summit caldera walls we reconstructed the time distribution of recent explosive events phreatomagmatic phreatic and their link with summit collapses and lateral flank effusive eruptions in historical time post 1640 ce we recognise two main clusters of explosive events frequent and violent phreatomagmatic to phreatic explosions occurred during the oldest cluster 1708 1878 and alternated with long lasting periods years to decades of summit effusive activity in contrast scarce and on average weak explosions occurred during the youngest cluster 1897 2012 when discrete and short lived 6 months effusive eruptions represent the main eruptive dynamics historical summit collapses pit craters and caldera all localised at the top of the summit cone were related to voluminous lateral eruptions and were followed by a significant decrease in eruptive rate however magma draining during lateral eruptions was not systematically associated with summit collapses or explosions the long lasting occurrence of magma at very shallow depth below the volcano summit followed by a rapid lateral drainage apparently represents a critical condition favouring magma groundwater interaction to produce explosive activity the prehistoric growth of the piton de la fournaise summit cone results chiefly from long lasting to continuous activity centred below its western side bory crater containing lava lakes high lava fountains long lasting effusive activity lava lakes ash plumes and block ejections were common types of eruptive dynamics in the historical past between 1640 and 1878 in this perspective short lived small volume eruptions and long pauses up to six years during the last century of activity of piton de la fournaise can be considered as a lull despite the high frequency of eruption 1 eruption 9 months on average temporal and spatial variations in recurrence rate and eruptive dynamics of basaltic volcanism such as those recognised at piton de la fournaise should be considered in the formulation of hazard assessments and in the interpretation of precursory patterns

sedimentation of holocene tufa influenced by the neolithic man an example from the sąspowska valley southern poland abstract a complex of inactive tufas the thickness of which reaches 3 5 m was studied in the lowermost segment of the s spowska valley in the krakow upland ojcow national park poland five fluvial tufa barrages were recognized they are composed of moss tufa and stromatolitic tufa accompanied with oncoidal rudstone and detrital tufa interbarrage ponded areas were filled with detrital tufa lutite and subordinately oncoidal rudstone limestone gravel and peat like deposit radiocarbon dates suggest that the tufa formed during subboreal boreal and atlantic time the main difference between the tufa in the s spowska valley and contemporaneous tufas in other valleys of the krakow upland is the higher amount of non carbonate fraction in the former other lower and middle holocene tufas of the krakow upland are composed mainly or exclusively of carbonate fraction the non carbonate fraction in fluviatile tufas in the s spowska valley resulted from erosion of loess cover in the upper part of the catchment the erosion was related to local activity of neolithic flint miners who cleared forest at a local scale dug shafts in loess cover and exploited flints from underlying weathered residuum of jurassic limestone consequently they made copious amounts of loose material available for transport down the valley and subsequent trapping within the tufa depositional system

first archeomagnetic data from kenya and chad analysis of iron furnaces from mount kenya and guera massif abstract the variation of the earth s magnetic field over the last millennia is poorly known in africa especially in sub saharan africa that represents less than 1 of the global archeomagnetic dataset fourteen iron furnaces from kenya and chad have been studied here for archeomagnetic purposes these structures were dated by 14c from the 14th century in kenya and from the 18 19th centuries in chad samples oriented with the plaster cap technique have been subjected to thermal and alternating field demagnetization rock magnetic analysis and paleointensity experiment with the classical thellier thellier technique corrected for anisotropy and cooling rate effects new directional data 4 from kenya and 10 from chad and one new paleointensity estimate from kenya 43 5 1 8 t were obtained the kenyan declinations are in good agreement with the geomagnetic global models but the inclinations are lower and the intensity higher than predicted for chad the new results prove the efficiency of the archeomagnetic dating with a precision that is better than radiocarbon for the 18 19th centuries

an updated archeomagnetic directional variation curve for france over the past two millennia following 25 years of additional data acquisition abstract nearly 40 years ago emile thellier published an article summarizing the archeomagnetic data he had obtained during his career which had allowed him to recover the main features of the directional variations of the geomagnetic field in france for the last two millennia this database went on to be significantly completed 25 years ago by ileana bucur who had taken over thellier s work on archeomagnetism this forms the current basis of our knowledge of the directional evolution of the geomagnetic field in france since then archeomagnetic studies have been continued at thellier s historical laboratory in saint maur this article presents the directional archeomagnetic data obtained in france over the past 25 years in this same laboratory a total of 528 new data are presented which together with the 170 results obtained on the french territory previously listed in bucur 1994 constitute the french directional database 698 data in all all but two of these data were obtained using the experimental protocol developed by e thellier based on the analysis of large samples and on a magnetic viscosity test that has proved its reliability on numerous occasions the directions from the entire french database have been precisely defined with 95 of the 95 values being less than 1 9 and 50 being less than 0 8 the selection of 286 data with dating uncertainties of 50 years allowed us to compute a new reference directional variation curve for france since the first century bc using sliding windows the variable durations and shifts of which were adapted to the time distribution of the available data and the bivariate extension of the fisher statistics this shows ample and smooth variations fairly similar to those previously determined from a much smaller database the resulting secular variation curve is particularly well suited for use in archeomagnetic dating

δ13c δ18o and deposition rate of tufa in xiangshui river sw china implications for land cover change caused by climate and human impact during the late holocene

the metamorphic environment of the sgurr beag slide a major crustal displacement zone in proterozoic moine rocks of scotland new evidence from the sw northern highlands of scotland establishes the southerly extension of the sgurr beag slide interpretation of changes in the mineralogy of calcsilicate rocks particularly the use of the anorthite content of plagioclase feldspar as an index of metamorphic grade together with consideration of the texture and mineralogy of pelitic rocks suggests that the slide juxtaposes crustal segments of different metamorphic grade and history movement on the slide post dates a major phase of regional metamorphism and two phases of regional deformation of precambrian age was synchronous with a regional fold forming event and regional metamorphism at or before c 467 ma caledonian and was followed by regional folding models of the thermal effects of displacement across syn metamorphic shear zones are investigated with particular reference to the roles of thermal relaxation and levels of shear strain a model based on the development of a ductile syn metamorphic asymmetric shear zone best explains the metamorphic patterns associated with the sgurr beag slide an original low to moderate easterly dip is implied with north westerly upthrusting of the eastern crustal block

unmasking the 1349 earthquake source southern italy paleoseismological and archaeoseismological indications from the aquae iuliae fault abstract the 9th september 1349 earthquake was one of the most catastrophic events experienced along the apennines at least three main shocks struck a vast area of the molise latium abruzzi regions and damage was even sustained by the distant monumental buildings of rome the southern most shock mw 6 7 occurred at the border between southern latium and western molise razing to the ground the towns of isernia venafro and cassino amongst others and devastating montecassino abbey as with other medieval catastrophic sequences e g in december 1456 mw 6 5 7 0 this earthquake has not yet been associated to any seismogenic source thus it still represents a thorn in the flesh of earthquake geologists we have here carried out a reappraisal of the effects of this earthquake and through an interpretation of aerial photographs and a field survey we have carried out paleoseismological analyses across a poorly known n130 normal fault that crosses the molise campania border this structure showed repeated surface ruptures during the late holocene the last one of which fits excellently with the 1349 event both in terms of the dating and the rupture dimension on the other hand archaeoseismic analyses have also indicated the faulting of an augustean aqueduct the amount of apparent offset of the aqueduct across the fault traces shows that there were other surface faulting event s during the roman high middle age period therefore in trying to ascertain whether these events were associated with known potentially of 346 ad or 848 ad or unknown earthquakes in the area it became possible that this 20 km long fault here named the aquae iuliae fault is characterized by high slip rates and a short recurrence time this is in agreement with both the similar behaviour of the neighbouring northern matese fault system and with recent gps analyses showing unexpectedly high extension rates in this area

prolonged wet period in the southwestern united states through the younger dryas the younger dryas was one of the more dramatic climatic transitions ever recorded how these types of climatic shifts are expressed in continental interiors is of primary scientific interest and of vital societal concern here we present a speleothem based absolutely dated record using uranium series data of climate change for the southwestern united states from growth chronology of multiple speleothems the stalagmite growth represents the onset of wetter climate 12 500 yr b p soon after the start of the younger dryas the wetter climate persisted a millennium beyond the termination of the younger dryas this wet cycle is likely related to a more southern positioning of the polar jet stream in response to cooler northern hemisphere climate the end of the wet period coincides with the peak of the holocene summer insolation maximum ca 10 500 yr b p the allerod prior to the younger dryas which corresponds to clovis occupation in the southwestern united states was drier in comparison and seems in line with a climatic contribution to megafauna extinction

dating young 1000 yr lava flow eruptions of piton de la fournaise volcano from size distribution of long lived pioneer trees dating recent lava flows is a critical issue to assess the volcanic hazards for nearby human populations but traditional methods such as radiocarbon dating are often not applicable we propose here a simple statistical method that relates the age of lava flows of the piton de la fournaise volcano pdf to the size of agarista salicifolia ericaceae a long lived pioneer tree that quickly establishes after eruption and able to live 600 years we measured the diameter at base of 711 trees on 20 dated lava flows between 1401 ce and 2007 ce we used a log log linear model to assess the relationship between maximum diameter at base of agarista salicifolia and the age of lava flows and showed a very strong correlation r2 0 987 p 2 2e 16 we then used this calibrated model to estimate the age of 11 lava flows between 1447 ce ci 1349 1531 and 1823 ce ci 1806 1839 these new ages combined with existing radiocarbon ages and historical records indicate three clusters of eruptions 1460 1630 1690 1840 since 1970 ce affecting both the caldera and the flanks of pdf we interpret such discontinuous dynamics made of periods of intense and low activity as evidencing pulses of high magma supply since at least the 11th century overall our work shows that dating lava flow with calibration based on the size distribution of long lived pioneer trees represents an accurate alternative method to redefine the hazard map of lava flow inundation the existence of long lived pioneer trees in several volcanic areas provides the opportunity to use the same framework in order to better understand eruption recurrence patterns

differences in the delta 18 o and delta 13 c signatures of seasonal laminae comprising travertine stromatolites abstract alternation of sparry and micritic laminae in modern nonmarine travertine stromatolites from creeks in the arbuckle mountains of oklahoma and from eocene hot water deposits in the palm park formation of new mexico represent seasonal accumulations the sparry laminae with upright biogenic structures represent spring summer accumulations whereas the micritic laminae with flat lying microbial remains represent fall winter accumulations the 18o values of the modern creek waters average 5 04 spring summer and 5 25 fall winter smow and calcite precipitated in equilibrium with these waters should have 18o values of approximately 6 4 and 5 2 pdb for spring summer and fall winter precipitates respectively 18o values for calcite which precipitated during three month periods on test objects in the creek waters average 6 5 for spring summer and 4 9 for fall winter the sparry and micritic laminae comprising the naturally occurring modern stromatolites from these creeks average 6 4 for sparry spring summer and 5 2 for micritic fall winter laminae thus the agreement between 18o values for precipitates which formed in isotopic equilibrium with the creek water composition precipitates on test objects and the sparry and micritic laminae comprising naturally occurring modern stromatolites confirm the seasonal origin of the laminae the 13c values for the creek waters the test objects and the naturally occurring laminae of the stromatolites are higher in the sparry spring summer than the micritic fall winter deposits the 18o values obtained as a result of lamina by lamina analyses of the eocene hot water travertine stromatolites of new mexico do not display a seasonal trend but the 13c values are consistently higher in the sparry laminae than in the micritic laminae in addition increased concentrations of trace elements occur in the sparry relative to the micritic laminae of the hot water stromatolites the lamina by lamina stable isotopic and trace elemental analyses provide confirmation of the seasonal origin of the sparry spring summer and micritic fall winter laminae comprising the ancient stromatolites

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

normal fault displacement dislocating a roman aqueduct of ephesos western turkey a 38 km long ancient aqueduct channel that served roman ephesos turkey was dislocated vertically over 3 m by a single seismic event on a normal fault a new channel was constructed downstream from the fault in roman times next to and partly on top of the original channel archaeological investigations and study of carbonate deposits suggest a causative seismic event in the second half of the second century ce probably in 178 ce after the original channel had functioned for 35 years the icme tepe fault was identified as responsible for the displacement and may still constitute a seismic and tsunami hazard for the turkish west coast specifically for the city of kusadasi ancient aqueducts of which more than 1400 are presently known are a promising and almost untapped archive for archaeoseismic studies especially in the mediterranean area

evidence for 830 years of seismic quiescence from palaeoseismology archaeoseismology and historical seismicity along the dead sea fault in syria an edited version of this paper was published in earth and planetary science letters by elsevier science elsevier science retains the copyright to this paper copyright 2003 see also http dx doi org 10 1016 s0012 821x 03 00144 4 http atlas geo cornell edu deadsea publications meghraoui2003 epsl htm

climatic significance of seasonal trace element and stable isotope variations in a modern freshwater tufa abstract we present a continuous 14 yr long 1985 to 1999 high resolution record of trace element mg sr ba u and stable isotope 13c 18o variations in a modern freshwater tufa from northwestern queensland australia by utilizing the temperature dependence of the 18o signal an accurate chronology was developed for the sampled profile which allowed a comparison of the chemical records with hydrological and meteorological observations as a consequence it was possible to constrain the relevant geochemical processes relating climate variables such as temperature and precipitation to their chemical proxies in the tufa record temperatures calculated from the mg concentrations of the tufa samples provide close approximations of average annual water temperature variations furthermore we demonstrate that temporal changes in mg ca water can be estimated using an empirically derived equation relating mg ca water to the sr ba ratio measured in the tufa samples by means of this relationship it is theoretically possible to determine the mg ca ratio of paleowaters and hence to derive reliable estimates of former water temperatures from the mg concentrations of fossil tufas from the study area sympathetic variations in sr ba and 13c along the sampled profile record changes in water chemistry which are most probably caused by variable amounts of calcite precipitation within the vadose zone of the karst aquifer this process is thought to be markedly subdued whenever the amount of wet season precipitation exceeds a given threshold accordingly distinct minima in sr ba and 13c are interpreted to reflect years with above average rainfall the pronounced seasonal and annual variability of the u concentration along the profile is thought to primarily record changes in the u flux from the soil to the water table we suggest that during intensive rain events u is transported to the phreatic zone by complexing organic colloids giving rise to conspicuous u maxima in the tufa after above average wet seasons this study demonstrates the potential of freshwater tufas to provide valuable information on seasonal temperature and rainfall variations if tufa deposits turn out to be reasonably resistant to secondary processes combined investigation of speleothems and tufas from the same area could become a promising approach in future research while speleothems offer continuous records of long term paleoenvironmental changes tufas could provide high resolution time windows into selected periods of the past

precise dating of dansgaard oeschger climate oscillations in western europe from stalagmite data the signature of dansgaard oeschger events millennial scale abrupt climate oscillations during the last glacial period is well established in ice cores and marine records but the effects of such events in continental settings are not as clear and their absolute chronology is uncertain beyond the limit of 14 c dating and annual layer counting for marine records and ice cores respectively here we present carbon and oxygen isotope records from a stalagmite collected in southwest france which have been precisely dated using 234u 230th ratios we find rapid climate oscillations coincident with the established dansgaard oeschger events between 83 000 and 32 000 years ago in both isotope records the oxygen isotope signature is similar to a record from soreq cave israel and deep sea records indicating the large spatial scale of the climate oscillations the signal in the carbon isotopes gives evidence of drastic and rapid vegetation changes in western europe an important site in human cultural evolution we also find evidence for a long phase of extremely cold climate in southwest france between 61 2 0 6 and 67 4 0 9 kyr ago

abiotic versus biotic controls on the development of the fairmont hot springs carbonate deposit british columbia canada the relict fairmont hot springs deposit formed largely of carbonates covers an area of 0ae 5k m 2 and is up to 16 m thick the triangle shaped discharge apron which broadens down valley is divided into a proximal part with beds dipping at 10 and a distal part with beds dipping at 10 to 15 the deposit is formed of the 1 basal macrophyte 2 lower carbonate 3 middle clastic 4 upper carbonate and 5 upper clastic sequences two charcoal samples embedded in the lower carbonate sequence yielded dates of 8690 90 and 8270 70 cal yr bp indicating that much of the deposit formed post glacially during the early to mid holocene deposit aggradation ceased in the mid to late holocene when the fairmont creek valley was incised the lower and upper carbonate sequences which are the thickest sequences are composed of nearly equal parts of travertine abiotic and tufa biotic with feather dendrite travertine radiating dendrite travertine and stromatolite tufa dominating competition between calcite precipitation rates and biotic growth rates controlled the distribution of tufa and travertine across the discharge apron calcite and biotic growth rates were controlled largely by flow velocity across the apron which in turn was controlled by topography and regular fluctuations in spring water discharge volume during times of high spring discharge slow sheet flow over the proximal part of the apron promoted stromatolite growth whereas fast turbulent flow on the distal part of the apron induced rapid feather dendrite formation during times of low spring discharge quiescent shallow evaporative pools conducive to radiating dendrite formation formed on the proximal part of the apron whereas slow flow on the distal part promoted stromatolite growth facies with high calcite supersaturation experienced rapid abiotic dendrite growth that precluded most biotic growth

correlation between climate events in the north atlantic and china during the last glaciation episodes of massive iceberg release heinrich events 1 3 into the north atlantic ocean during the last glaciation were associated with recurring episodes of unusually cold north atlantic surface water bond cycles 4 and cold air temperatures over greenland dansgaard oeschger events 5 6 four of the youngest of these cold events have also been reported in climate records from sites outside the north atlantic region7 but until now the entire suite has been identified only in north atlantic marine sediments greenland ice core records and tentatively in french lake sediments8 here we examine grain size data from chinese loess and intercalated accretionary palaeosols of last glacial age for evidence of similar climate signals remote from the north atlantic region we see grain size maxima with ages that match those of the last six heinrich events which we interpret as an indication of the changing strength of the east asian winter monsoon which largely controls the transport and deposition of central asian aeolian dust thus it seems that these heinrich events have left their signature in the chinese loess record this is consistent with simulations of the glacial climate9 which imply that the climates of the north atlantic and china were linked by the effect of westerly winds

distortion of the geomagnetic field in volcanic terrains an experimental study of the mount etna stratovolcano abstract the inclination i declination d and total intensity f of the geomagnetic field were measured on mount etna in 1989 1991 at a dozen sites previously sampled for archeomagnetic studies the purpose of the work was to determine the variations of these parameters at 30 cm above ground level and how the distortion from the main field can affect the archeomagnetic record of volcanic rocks ten measurements were usually performed at each site with a three component flux gate magnetometer whose estimated precision is 0 2 on direction and 50 nt on intensity this was considered sufficient on volcanic areas with highly magnetized rocks and where the geomagnetic gradient may be in excess of 1000 nt m results averaged for each site generally show small variations in intensity 3 of the total field and direction 1 5 the averaged values of the 12 sites i 52 6 d 0 3 f 44010 nt are very close to those measured in sedimentary terrain away from the volcano i 52 9 d 0 35 f 44110 nt themselves consistent with the interpolated igrf in eastern sicily the largest deviations of the geomagnetic direction have been observed on four sites three of them located on the south flank between 1900 and 700 m elevation it is suggested that these anomalies are mainly related to dyke swarms which are common within the south rift zone of mount etna our findings show that reliable archeomagnetic results can be obtained from volcanic rocks provided that lavas of the same eruption are sampled on several sites distributed over the largest possible area