modification and preservation of environmental signals in speleothems speleothems are primarily studied in order to generate archives of climatic change and results have led to significant advances in identifying and dating major shifts in the climate system however the climatological meaning of many speleothem records cannot be interpreted unequivocally this is particularly so for more subtle shifts and shorter time periods but the use of multiple proxies and improving understanding of formation mechanisms offers a clear way forward

middle miocene ocean climate transition high resolution oxygen and carbon isotopic records from deep sea drilling project site 588a southwest pacific high resolution stable isotopic records are presented for the epi benthic foraminifer cibicidoides the inferred shallow dwelling planktonic globigerinoides quadrilobatus and the inferred deep dwelling planktonic globoquadrina dehiscens from the middle miocene 16 12 ma of deep sea drilling project site 588a lord howe rise southwest pacific high resolution multiple species oxygen and carbon isotopic data define the timing and character of the well known middle miocene climatic oceanographic transition with a resolution comparable to quaternary records the benthic foraminiferal 18o record is marked by several large fluctuations from 16 to 14 8 ma followed by a series of rapid 50 kyr 18o increases that suggest a new state of the ocean climate system after 14 8 ma the total middle miocene benthic oxygen isotopic increase of 1 2 is largely incorporated in two steps an increase of 0 8 from 14 5 to 14 0 ma and a second increase of 0 7 from 13 45 to 12 45 ma each step is comprised of a series of marked 18o increases indicative of rapid east antarctic ice sheet growth and contemporaneous deepwater cooling a strong covariance of 0 7 between the benthic and deep dwelling planktonic species from 14 5 to 14 0 ma including a rapid increase from 14 1 to 14 05 ma suggests a 0 7 increase in the 18o composition of seawater 18osw because of east antarctic ice sheet growth comparison of the 18o record of gs quadrilobatus suggests that surface waters warmed at this site by 3 c from 14 1 to 13 6 ma carbon isotopic time series for each species generally covary throughout the early to middle miocene interval 16 12 ma confirming that 13c variations in this interval largely represent reservoir changes high resolution 13c data allow improved resolution of the latter five of six 13c maxima within the well known early to middle miocene carbon isotopic excursion the monterey carbon isotopic excursion from 17 0 to 13 5 ma this is useful for global correlation the last of these maxima ends with a 1 decrease centered from 13 9 to 13 7 ma 300 kyr after the 18o increase considered to reflect east antarctic ice growth covariance between benthic 18o and 13c from 16 to 13 8 ma suggests a sensitive relation between global carbon cycling and the ocean climate system prior to 13 8 ma episodic increases in organic carbon burial may have contributed to deep sea benthic 13c maxima and synchronous global cooling the positive relationship ended at 13 8 ma indicative of changing relations between global carbon cycling and the ocean climate system brought on by the increased stability of the east antarctic ice sheet after a major growth phase from 14 5 to 14 0 ma

the geomorphic dynamics and environmental history of an upper deltaic floodplain tract in the sacramento san joaquin delta california usa a multi proxy approach was used to examine the geomorphic dynamics and environmental history of an upper deltaic oodplain tract in the sacramento san joaquin delta california three long cores were collected from the mccormack williamson tract mwt and these cores were analyzed for bulk density loss on ignition ne clay and silt content al concentration magnetic susceptibility pollen and charcoal radiocarbon dates obtained for the cores were converted into calendar years and an age depth model was constructed long term vertical accretion and sedimentation rates were estimated from the age depth model cross core relations show that coarse sediment generally accumulates more rapidly and has greater magnetic susceptibility compared to ne sediment percentage ne and loi data show a strong linear relationship that indicates ooding is the primary mechanism for the deposition of particular organic matter on the oodplain and that landscape wash load has contributed a highly consistent fraction of persistent organic matter averaging 5 5 per cent to the site down core grain size pro les show two hydrological domains in the cores namely millennial ne coarse uctuations superimposed on general up core ning coarse sediment is viewed as channel or near channel overbank deposits whereas ne deposits are considered to be distal overbank ood deposits the coarse ne uctuations are indicative of changing depositional settings as channels migrated laterally across mwt whereas the upward ning trend re ects a combination of self limiting overbank deposition as oodplain elevation increased and decreasing competence as sea level rise reduced ood pulse energy slopes mwt has been cross cut and incised numerous times in the past only to have the channels abandoned and subsequently lled by ne sediment the channels around mwt attained their modern con guration about 4000 years ago mwt likely came under tidal in uence at about 2500 cal bp wetlands have recently developed on mwt but they are inorganic sediment dominated copyright 2004 john wiley sons ltd

miocene stable isotopic stratigraphy and magnetostratigraphy of buff bay jamaica previously reported biostratigraphic relationships from middle upper miocene sections exposed near buff bay jamaica 18 n tropical bioprovince differ from the subtropical north atlantic sites 563 and 558 time scales for this interval rely on correlations established at these subtropical sites and the differences with the tropical section have implications to global correlations planktonic foraminiferal zones n13 and n15 are thick at buff bay but are virtually absent at sites 563 and 558 nannofossil zone nn9 is associated with zone n15 and uppermost zone n14 at buff bay but is associated with zone n16 at the other sites magnetostratigraphic data presented here further complicate the interpretation zone nn9 is associated with a thick normal magnetozone at sites 563 and 558 at buff bay it is associated with a thick reversed magnetozone although a secondary magnetization at buff bay makes it difficult to identify confidently miocene normal magnetozones the thick reversed magnetozone most likely represents the paleomagnetic field and correlates with chron c5r the magnetobiostratigraphic relationships require either diachrony of taxa or two mutually exclusive hiatuses in jamaica and the north atlantic we address this problem by analyzing benthic foraminiferal 18 o and 13 c from the buff bay section these isotopic data allow us to evaluate three hypotheses that reconcile the magneto bio and isotopic stratigraphic data and conclude that the first and last occurrences of five taxa were diachronous by 0 3 0 5 m y between tropical and subtropical locations this requires revised age estimates for late middle to early late miocene biostratigraphic datum levels we suggest that the ranges of several taxa are useful for endemic tropical or subtropical zonations but correlations between the low and midlatitudes were affected by an increase in latitudinal thermal gradients during the late middle miocene however we admit that further studies are needed before this issue is resolved

variability of el nino southern oscillation activity at millennial timescales during the holocene epoch the variability of el nino southern oscillation enso during the holocene epoch in particular on millennial timescales is poorly understood palaeoclimate studies have documented enso variability for selected intervals in the holocene but most records are either too short or insufficiently resolved to investigate variability on millennial scales1 2 3 here we present a record of sedimentation in laguna pallcacocha southern ecuador which is strongly influenced by enso variability and covers the past 12 000 years continuously we find that changes on a timescale of 2 8 years which we attribute to warm enso events become more frequent over the holocene until about 1 200 years ago and then decline towards the present periods of relatively high and low enso activity alternating at a timescale of about 2 000 years are superimposed on this long term trend we attribute the long term trend to orbitally induced changes in insolation and suggest internal enso dynamics as a possible cause of the millennial variability however the millennial oscillation will need to be confirmed in other enso proxy records

millennial scale temperature variations in north america during the holocene 1 a mean continental july temperature reconstruction based on pollen records from across north america quantifies temperature variations of several timescales for the past 14 000 cal yr bp in north america temperatures increased nearly 4 c during the late glacial reaching maximum values between 6000 and 3000 cal yr bp after which mean july temperatures decreased superimposed on this orbital scale trend are millennial scale temperature variations that appear coherent in structure and frequency with highresolution ice marine and other terrestrial paleoclimate records of the holocene during the holocene climate in north america appears to have varied periodically every 1100 years rather than the 1500 year cycle found during the last glacial period coherence at frequencies between 900 and 1100 years between land ice and ocean records suggests a common forcing associated with widespread surface impacts during the holocene these results provide important insight to the global warming debate as the observed twentieth century temperature increase appears unprecedented compared to our mean north american temperature reconstruction of the past 14 000 years

insolation values for the climate of the last 10 million years new values for the astronomical parameters of the earth s orbit and rotation eccentricity obliquity and precession are proposed for paleoclimatic research related to the late miocene the pliocene and the quaternary they have been obtained from a numerical solution of the lagrangian system of the planetary point masses and from an analytical solution of the poisson equations of the earth moon system the analytical expansion allows the direct determination of the main frequencies with their phase and amplitude numerical and analytical comparisons with the former astronomical solution ber78 are performed so that the accuracy and the interval of time over which the new solution is valid can be estimated the corresponding insolation values have also been computed this analysis leads to the conclusion that the new values are expected to be reliable over the last 5 ma in the time domain and at least over the last 10 ma in the frequency domain

holocene vegetation climate and lake level changes in the interior douglas fir biogeoclimatic zone british columbia chilhil phair fishblue and horseshoe lakes in the southern interior of british columbia were cored and analyzed for pollen phair lake was also examined for plant macrofossils and aquatic molluscs two dated volcanic tephras mazama and bridge river are present in three of the four lakes and together with radiocarbon dates provide an absolute chronology for pollen influx calculations and stratigraphic correlation abrupt changes in sediment type at phair lake about 5650 and 2000 years ago correlate with neoglacial advances near the coast interior transition pollen changes suggestive of moister conditions and the presence of an aquatic mollusc valvata sincera helicoidea at phair and chilhil lakes are consistent with the neoglacial evidence of cooler and wetter conditions after about 2400 years ago the driest part of the holocene was the early pre mazama ca 6600 6800 years ago interval when the vegetation was more open and herb rich and the lake levels were lower than at present wetter clima

elemental carbon record of paleofire history on the chinese loess plateau during the last 420 ka and its response to environmental and climate changes an elemental carbon ec record covering the last 420 ka was reconstructed using chemical oxidation method on a loess and paleosol sequence from the lingtai section on the chinese loess plateau the ec record reveals the paleofire history and its relationship with climate and vegetation changes on the chinese loess plateau our results show that the ec abundance is generally higher in the paleosols than in the loess layers showing a glacial interglacial pattern which is coincident with biomass changes this variation pattern indicates that paleofires were intensified when biomass accumulated and climate changed abruptly especially from wet to dry conditions the ec abundance increases sharply at similar to 130 kab p indicating a dramatic change in the vegetation and climate variation patterns the occurrence of a peak value with the highest average ec abundance in the holocene may reflect the occurrence of a major climate event at similar to 6 kab p and may also be partly due to more frequent anthropogenic fire usages c 2007 elsevier b v all rights reserved

seasonal contributions of catchment weathering and eolian dust to river water chemistry northeastern tibetan plateau chemical and sr isotopic constraints relative to winter it is noticeable that both the lowest and the highest 87 sr 86 sr values of the buha river waters occurred in the monsoon season indicating a sensitive response of carbonate versus silicate weathering sources to hydrological forcing on a seasonal basis a significant decrease in na cation together with lower sr isotope ratios is consistent with a greater proportion of carbonate weathering relative to silicate weathering in the early monsoon season high temperature and increased rainfall during the peak of the monsoon facilitate an increased proportion of ions derived from silicates partly from groundwaters to river water in other seasons elemental and 87 sr 86 sr ratios vary much less indicating a constant ratio of silicate to carbonate weathering consistent with limited variation in discharge our results highlight that in a semiarid region where climatic conditions vary seasonally in addition to silicate and carbonate contributions supply from eolian dust may also play a significant role in controlling seasonal variations in chemistry of river waters

genesis and microstratigraphy of calcite coralloids analysed by high resolution imaging and petrography abstract the genesis of calcite coralloid speleothems from lamalunga cave southern italy is here investigated from a purely petrographic perspective which constitutes the basis for any subsequent chemical investigation lamalunga cave coralloids formed on bones and debris on the floor of the cave they consist of elongated columnar crystals whose elongation progressively increases from the flanks to the tips of the coralloid forming a succession of lens shaped layers which may be separated by micrite or impurity rich layers organic molecules are preferentially concentrated toward the centre of convex lenses as highlighted by epifluorescence their occurrence on cave floor lens shaped morphology and concentration of impurities toward the apex of the convex lenses supports the hypothesis that their water supply was hydroaerosol generated by the fragmentation of cave drips evaporation and degassing preferentially occurred on tips enhancing the digitated morphology and trapping the organic molecules and impurities carried by the hydroaerosol between the growing crystals which became more elongated micrite layers that cap some coralloid lenses likely identify periods when decreasing in hydroaerosol resulted in stronger evaporation and higher supersaturation with respect to calcite of the parent film of fluid this interpretation of coralloid formation implies that these speleothems can be used to extract hydroclimate information

north pacific late miocene correlations using microfossils stable isotopes percent caco3 and magnetostratigraphy abstract a multidisciplinary approach to stratigraphy based on magnetostratigraphy stable isotopes percent caco 3 and microfossils provides a framework for paleoclimatic and paleoceanographic reconstruction of the equatorial and north pacific a high resolution biochronologic time scale has been achieved through integration of diatom radiolaria coccolith and planktic foraminifer datum levels with direct or indirect correlations to the paleomagnetic time scale over 70 datum levels have been identified between 12 5 and 5 ma from low and middle latitudes resulting in an unprecedented time control this high resolution biostratigraphic control combined with stable isotopic and percent caco 3 analyses permits identification of regional as well as global paleoceanographic events

early last glacial intra interstadial climate variability recorded in a sardinian speleothem chemical and physical proxy data from a precisely dated early last glacial 113 110 ka mis5d sardinian stalagmite reveal a sub millennial scale cool dry climate event centered at 112 0 0 52 0 59 ka followed by a rapid return to warm wet conditions at 111 76 0 43 0 45 ka comparison with regional speleothem records and the palaeotemperature proxy record from the ngrip ice core greenland suggests that this event corresponds to greenland interstadial gi 25b and 25a an intra interstadial climate oscillation within gi 25 according to the recent greenland stratigraphic framework the speleothem age is in reasonable agreement within 0 8 kyr with that of the corresponding event in greenland based on the gicc05modelext ice chronology but is older by about 3 7 kyr than the greenland age based on the aicc2012 chronology

pollen based continental climate reconstructions at 6 and 21 ka a global synthesis subfossil pollen and plant macrofossil data derived from 14c dated sediment profiles can provide quantitative information on glacial and interglacial climates the data allow climate variables related to growing season warmth winter cold and plant available moisture to be reconstructed continental scale reconstructions have been made for the mid holocene mh around 6 ka and last glacial maximum lgm around 21 ka allowing comparison with palaeoclimate simulations currently being carried out as part of the fifth assessment report ar5 of the intergovernmental panel on climate change the synthesis of the available mh and lgm climate reconstructions and their uncertainties obtained using modern analogue regression and model inversion techniques is presented for four temperature variables and two moisture variables reconstructions of the same variables based on surface pollen assemblages are shown to be accurate and unbiased reconstructed lgm and mh climate anomaly patterns are coherent consistent between variables and robust with respect to the choice of technique they support a conceptual model of the controls of late quaternary climate change whereby the first order effects of orbital variations and greenhouse forcing on the seasonal cycle of temperature are predictably modified by responses of the atmospheric circulation and surface energy balance

world wide delivery of river sediment to the oceans new data and new estimates from old data show that rivers with large sediment loads annual discharges greater than about 15 times 10 6 tons contribute about 7 times 10 9 tons of suspended sediment to the ocean yearly extrapolating available data for all drainage basins the total suspended sediment delivered by all rivers to the oceans is about 13 5 times 10 9 tons annually bedload and flood discharges may account for an additional 1 2 times 10 9 tons about 70 of this total is derived from southern asia and the larger islands in the pacific and indian oceans where sediment yields are much greater than for other drainage basins

speleothems as high resolution paleoflood archives abstract over the last two decades speleothems have become widely utilized records of past environmental variability typically through their stable isotopic and trace elemental chemistry numerous speleothem researchers have identified evidence of flooding recorded by detrital layers trapped within speleothems but few studies have developed paleoflood reconstructions from such samples because they can be precisely dated are generally immune to post depositional distortion or erosion and can be tied to a fixed elevational baseline speleothems hold enormous potential as high resolution archives of cave floods and thus as proxies for extreme rainfall or other hydrologic drivers of cave flooding here we review speleothem based paleoflood reconstruction methods identify potential biases and pitfalls and suggest standard practices for future studies

a holocene record of marine fish remains from the northeastern pacific abstract ocean drilling program leg 169s retrieved a complete holocene sequence from saanich inlet british columbia canada fish and diatom remains were extracted from sediments at site 1034 very small fish bones teeth and scales were ubiquitous except in the lowermost glaciomarine clays scales degraded with depth in the identifiable fraction pacific herring were the most abundant with pacific hake and cartilaginous fish yielding significant fractions fish remains appear just before 12 000 bp but greatest diversity does not occur until about 6500 bp a smoothed abundance curve highlights two periods of maximal abundance at about 1500 and 6500 bp abundances in the last 1000 years are lower than the rest of the record a correlation with abundances of seven phytoplankton taxa is significant diatoms explain about a third of the variance this study demonstrates the use of fish and diatoms from the same paleosedimentary matrix to examine millennia scale correlations between primary and tertiary production

speleothem palynology an undervalued tool in quaternary studies palynological analysis of cave sediments in particular the analysis of pollen from speleothems is not a widely adopted approach to palaeoenvironmental studies in the british isles this disregard of speleopalynology may be due to the lack of understanding of the cave pollen taphonomy and uncertainty and suspicion as to what cave pollen spectra actually represent however a number of studies of pollen from caves have been carried out particularly in belgium france and spain which have demonstrated speleothem pollen spectra to be representative of contemporary vegetation above the cave with pollen generally well preserved speleothems have the distinct advantage over other pollen sources that they can be dated by high precision tims u th dating up to an order of magnitude further back in time than 14c dating of organic sediments would allow this potentially allows previously unconstrained middle pleistocene palynological records to be precisely and accurately dated thus providing a geochronologically controlled terrestrial record of palaeoenvironmental change this paper presents a timely review of speleothem palynology aiming to eliminate biases and misconceptions and illustrate the enormous potential this unique source of palaeoenvironmental data holds particularly in providing accurately dated pollen records from previously understudied environments and time periods

gypsum speleothems in lava tubes from lanzarote canary islands ion sources and pathways abstract lava tubes from lanzarote island in the canary archipelago commonly show white speleothems that stand out from the black basaltic rock mineralogical analyses of the speleothems from el covon and chifletera lava tubes show that gypsum is the dominant mineral with minor amounts of halite speleothems composed of microcrystalline gypsum up to 150 m long are coatings globules or extensive white powder accumulations covering the tube floor those composed of macrocrystalline gypsum with millimetric size tabular and lenticular crystals are crusts and stalactites uranium series dating of speleothems show ages ranging from 6217 1644 yr to 40 039 4748 yr 34s and the 18o of gypsum speleothems 34s is 20 97 v cdt and 18o is 9 78 v smow is similar to that of sulphate dissolved in seawater 87sr 86sr from speleothems 0 708665 0 708976 suggests that the main source of ca is seawater but additional ca contributions from aeolian dust have reduced the sr isotope values these data support the idea that gypsum precipitates in the lava tube by evaporation of marine spray or solutions derived from marine spray two probable vias for ions input into the lava tube are considered 1 sea spray circulating through the lava tube 2 low frequency rain infiltration leaching the marine spray salts precipitated at the surface the constant supply of ions from sea spray air currents in the cave and the fast but partial evaporation due to the high relative humidity in the lava tube favours accumulation of major amounts of gypsum and subordinately halite scarcity of precipitation in the western canary islands prevents dissolution of gypsum speleothems

source and genesis of sulphate and phosphate sulphate minerals in a quartz sandstone cave environment gypsum caso4 2h2o alunite kal3 so4 2 oh 6 and rare phosphate sulphate sanjuanite al2 po4 so4 oh 9 h2o and rossiantonite al3 po4 so4 2 oh 2 h2o 14 have recently been identified as secondary mineral deposits in different quartz sandstone caves in the gran sabana region venezuela due to the extended time scale required for speleogenesis in the hard and barely soluble quartz sandstone lithology these caves are considered to be as old as 20 to 30 my the study of these peculiar secondary mineral deposits potentially reveals important insights for understanding the interaction between deep superficial and atmospheric processes over thousands to perhaps millions of years in this study chemical and petrographic analyses of potential host rock sources sulphur and oxygen isotope ratios and meteorological hydrological and geographical data are used to investigate the origin of sulphates and phospho sulphates the results suggest that the deposition of sulphates in these caves is not linked to the quartz sandstone host rock rather these mineral deposits originate from an external atmospheric sulphate source with potential contributions of marine non sea salt sulphates terrestrial dimethyl sulphide and microbially reduced h2s from the forests or peatbogs within the watershed air currents within the caves are the most plausible means of transport for aerosols driving the accumulation of sulphates and other secondary minerals in specific locations moreover the studied sulphate minerals often co occur with silica speleothems of biological origin although this association would suggest a possible biogenic origin for the sulphates as well direct evidence proving that microbes are involved in their formation is absent nonetheless this study demonstrates that these quartz sandstone caves accumulate and preserve allogenic sulphates playing a yet unrecognized role in the sulphur cycle of tropical environments

polycyclic aromatic hydrocarbons in stalagmites occurrence and use for analyzing past environments this article presents a preliminary investigation into the value of polycyclic aromatic hydrocarbons pahs as markers for interpreting past environments in karst areas we analyzed a core sample representing the last 400 years growth from a massive stalagmite in the chevaline cave vercors france together with the soil overlying the karst directly above the stalagmite during the last millennium this area has been profoundly affected by human activities such as slash and burn agriculture charcoal burning and forestry these activities may have induced changes in pah production in the soil and thus in the pah record in the stalagmite pahs were extracted using both the soxhlet method and the ultrasonic method in order to compare extraction yields the ultrasonic method in conjunction with classic hplc fluo analysis was adopted for the analyses as it gave the greater yields pah distributions were obtained for the stalagmite and for the overlying soils the sum of the pah measured in the stalagmite ranges from 18 to 30 ng g furthermore the more soluble and labile pahs lighter than anthracene dominated the pah distribution in the stalagmite about 90 of low molecular weight pah however we did not find any obvious source fingerprints in the soil or the stalagmite and we observed an unexpected discrepancy between the pah distributions in the stalagmite and its stratigraphy which is controlled by mineral and organic inclusions although pah analyses can provide valuable data about the transfer of organic compounds in the karst it is difficult to extract meaningful paleoenvironmental information from pahs in stalagmites over the time scale of this study

late quaternary speleothem pollen in the british isles as with many terrestrial areas the british quaternary sequence is characterised by incomplete fragmentary records whose correlation is based on stratigraphic or biostratigraphic techniques due to the lack of radiometric ages beyond the 40 kyr limit of 14c dating speleothems secondary cave calcite deposits offer a significant advantage over many sources of palaeoenvironmental information they can be dated to a high precision and accuracy by uranium thorium 238u 230th thermal ionisation and inductively coupled plasma icp mass spectrometry in the time period back to 500 kyr they may also contain sufficient well preserved pollen representative of contemporary vegetation above the cave to allow palaeoenvironmental reconstruction this study adopts the novel approach of combining pollen and thermal ionisation mass spectrometric tims u th dating of british speleothems to produce well constrained palaeoenvironmental records we report for the first time precisely dated records of pollen assemblages from speleothems suggesting the presence of thermophilous arboreal species in phases previously considered to have been consistently cool or cold and devoid of trees copyright 2007 john wiley sons ltd

the role of microorganisms in the formation of calcitic moonmilk deposits and speleothems in altamira cave abstract bacteria are able to induce carbonate precipitation although the participation of microbial or chemical processes in speleothem formation remains a matter of debate in this study the origin of carbonate depositions such as moonmilk an unconsolidated microcrystalline formation with high water content and the consolidation of carbonate precipitates into hard speleothems were analyzed the utilized methods included measurements of the composition of stable isotopes in these precipitates fluorimetric determinations of rna dna ratios and respirometric estimations in altamira cave results from isotope composition showed increases of the 18 o and 13 c ratios from moonmilk in the very first stages of formation toward large speleothems estimates of rna dna ratios suggested an inactivation of microorganisms from incipient moonmilk toward consolidated deposits of calcium carbonate respiratory activity of microorganisms also showed a significant decrease in samples with accumulated calcite these results suggest that bacterial activity induces the conditions required for calcium carbonate precipitation initiating the first stages of deposition progressive accumulation of carbonate leads towards a less favorable environment for the development of bacteria on consolidated speleothems the importance of bacteria in carbonate deposition decreases and chemical processes gain importance in the deposition of carbonates

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

9000 years of salmon fishing on the columbia river north america a large assemblage of salmon bones excavated 50 yr ago from an 10 000 yr old archaeological site near the dalles oregon usa has been the primary evidence that early native people along the columbia river subsisted on salmon recent debate about the human role in creating the deposit prompted excavation of additional deposits and analysis of archaeologic geologic and hydrologic conditions at the site results indicate an anthropogenic source for most of the salmonid remains which have associated radiocarbon dates indicating that the site was occupied as long ago as 9300 cal yr b p the abundance of salmon bone indicates that salmon was a major food item and suggests that migratory salmonids had well established spawning populations in some parts of the columbia basin by 9300 8200 yr ago

high resolution palaeofire signals from christina lake alberta a comparison of the charcoal signals extracted by two different methods abstract two high resolution palaeofire signals were extracted from the annually laminated sediment of christina lake in the boreal forest of alberta canada a charcoal curve focusing on large charcoal fragments 125 m was extracted by the sieving method described by whitlock and millspaugh a carbon curve which includes all size fractions of charcoal was extracted by a method modified from winkler s chemical assay method modifications included increasing the duration of nitric acid treatment to 2 h and using a total carbon analyser tca rather than standard loss on ignition these adjustments resulted in a carbon curve which is unaffected by clay water losses and subtle changes in sedimentology which were problematic in the original gravimetric technique the sensitivity of the tca allowed subtle shifts in carbon i e charcoal abundance to be detected in lake sediments with low levels of charcoal when compared with the known fire history near the lake since 1900 the sieved charcoal curve was most responsive to fires known to burn near the shore of the lake and less responsive to fires burning elsewhere in the watershed the tca carbon curve was somewhat more sensitive than the sieved charcoal curve for detecting fires in the drainage basin which did not burn to the lake edge the tca carbon curve was strongly correlated with sediment influx suggesting stream inputs of charcoal are the dominant influence on this signal the peak in response of the tca curve to known fire events was sometimes lagged by several years suggesting that it can take several seasons for the bulk of stream transported charcoal to make its way from the watershed to its final deposition site in the lake very large fires burning just outside the drainage basin of the lake were not detected by either method suggesting that both of the methods used are sensitive only to fires burning in the watershed and that long distance aerially dispersed charcoal is insignificant at this site

paleoclimate simulations for north america over the past 21 000 years features of the simulated climate and comparisons with paleoenvironmental data maps of upper level and surface winds and of surface temperature and precipitation illustrate the results of a sequence of global paleoclimatic simulations spanning the past 21 000 years for north america we review a the large scale features of circulation temperature and precipitation that appear in the simulations from the ncar community climate model version 1 ccm 1 b the implications of the simulated climate for the past continental scale distributions of three plant taxa picea spp pseudotsuga menziesii and artemisia tridentata which are broadly representative of the vegetation across the continent and c the potential explanations in terms of atmospheric circulation or surface energy and water balance processes for mismatches between the simulations and observations most of the broad scale features of previous paleoclimatic simulations with the ncar ccm 0 for north america are present in the current simulations many of the elements of a conceptual model based on previous climate simulations that describes the controls of paleoclimatic variations across north america during the past 21 000 years are found in simulations reviewed here these include 1 displacement of the jet stream by the laurentide ice sheet to the south of its present position in both winter and summer 2 generation of a glacial anticyclone over the ice sheet at the lgm and the consequent induction of large scale sinking motions induced over eastern north america 3 changes in the strength of surface atmospheric circulation features through time including weakening of the aleutian low in winter and strengthening of the eastern pacific and bermuda high pressure systems in summer as the ice sheet decreased in size 4 development of a heat low at the surface and a strengthened ridge in the upper atmosphere over the continent at the time of the maximum summer insolation anomaly 5 increases in summer temperature earlier in regions remote from the ice sheet these increases appear earlier in the present ccm 1 simulations than in the previous ccm 0 ones however and 6 continuation of negative winter temperature anomalies into the middle holocene in general simulated surface conditions that are discordant with paleoenvironmental observations can be attributed to the simulation of particular atmospheric circulation patterns e g those that suppress precipitation or advect warm air into a region with these mismatches amplified in beringia and the southeastern united states by surface energy and water balance processes

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

extension of the astronomically calibrated polarity time scale to the miocene pliocene boundary the early pleistocene to late pliocene astronomically calibrated time scale of shackleton et al 1 and hilgen 2 is extended to the miocene pliocene boundary this is done by correlating the detailed record of caco3 cycles in the trubi and the lower part of the overlying narbone formation rossello composite section sicily to the astronomical record using 1 inferred phase relations between these caco3 cycles and the corresponding orbital cycles of precession and eccentricity and 2 calibration points provided by the previously established astronomical calibration of sapropelitic layers which occur in the topmost part of the caco3 record 2 this correlation allows all small scale caco3 cycles in the rossello composite section to be coded after the correlative precession peak and to be dated astronomically with an accuracy of 1 ky in combination with the available high resolution magnetostratigraphy it further allows the construction of an astronomically calibrated geomagnetic polarity time scale for the major part of the gilbert and gauss chrons this new time scale gives ages for the reversal boundaries of the kaena 3 04 3 11 ma and mammoth 3 22 3 33 ma the gilbert gauss chron boundary 3 58 ma and the reversal boundaries of the cochiti 4 18 4 29 ma nunivak 4 48 4 62 ma sidufjall 4 80 4 89 ma and thvera 4 98 5 23 ma these ages are significantly older than the ages given by conventional time scales age discrepancies gradually increase with increasing age the age of 5 32 ma for the miocene pliocene boundary as defined by the base of the trubi on sicily is almost 0 5 m y 9 5 older than the presently accepted age of 4 86 ma 3 these considerable discrepancies with the conventional time scale can either be explained by an consistent error in the decay constants used in k ar radiometric dating or more likely by diffusional loss of radiogenic argon

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

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

sea level change and paleogeographic reconstructions southern vancouver island british columbia canada abstract forty eight new and previously published radiocarbon ages constrain deglacial and postglacial sea levels on southern vancouver island british columbia sea level fell rapidly from its high stand of about 75 m elevation just before 14 000 cal bp 12 000 radiocarbon yrs bp to below the present shoreline by 13 200 cal bp 11 400 radiocarbon years bp the sea fell below its present level 1000 years later in the central strait of georgia and 2000 years later in the northern strait of georgia reflecting regional differences in ice sheet retreat and downwasting direct observations only constrain the low stand to be below 11 m and above 40 m analysis of the crustal isostatic depression with equations utilizing exponential decay functions appropriate to the cascadia subduction zone however places the low stand at 30 5 m at about 11 200 cal bp 9800 bp the inferred low stand for southern vancouver island when compared to the sea level curve previously derived for the central strait of georgia to the northwest generates differential isostatic depression that is consistent with the expected crustal response between the two regions morphologic and sub bottom features previously interpreted to indicate a low stand of 50 to 65 m are re evaluated and found to be consistent with a low stand of 30 5 m submarine banks in eastern juan de fuca strait were emergent at the time of the low stand but marine passages persisted between southern vancouver island and the mainland the crustal uplift presently occurring in response to the late pleistocene collapse of the southwestern sector of the cordilleran ice sheet amounts to about 0 1 mm yr the small glacial isostatic adjustment rate is a consequence of low viscosity mantle in this tectonically active region

miocene nannofossil chronology in the north atlantic dsdp site 608 abstract dsdp north atlantic site 608 yielded an excellent miocene pelagic section which affords a further opportunity for elucidating the chronology of the calcareous nannofossil succession in the framework of magnetostratigraphic control most of the conventional zonal markers have been documented for this site and some of the earlier results are confirmed and refined in addition several unconventional and less known markers have been added the first two are the highest last occurrence of sphenolithus delphix and sphenolithus capricornutus at 23 6 ma which is immediately above the oligocene miocene boundary as identified by the last occurrence of reticulofenestra bisecta at 23 7 ma the next unconventional datum is the highest last occurrence of ilselithina fusa at 22 8 ma which is also the highest last occurrence of helicosphaera recta calcidiscus tropicus lowest first occurrence is at 19 5 ma which is also the lowest occurrence of sphenolithus belemnos and calcidiscus leptoporus lowest first occurrence coincides with that of sphenolithus heteromorphus at 18 5 ma sphenolithus dissimilis highest last occurrence is at 18 2 ma and the calcidiscus premacintyrei lowest first and highest last occurrences are respectively at 17 7 and 11 7 ma discoaster braarudii occurs from 11 6 to 11 3 ma and its highest last occurrence corresponds to that of cyclicargolithus floridanus minylitha convallis occurs from 9 0 to 6 9 ma within the range of minylitha at 8 0 ma a major shift occurs in reticulofenestrid placoliths from dominantly large reticulofenestra pseudoumbilicus and medium size reticulofenestra minutula species below to significant numbers of very small species dictyococcites productus and gephyrocapsa above this is interpreted to be a major though perhaps seasonal change of productivity of the north atlantic at site 608 a new genus and species cryptococcolithus takayamae is described and a variety reticulofenestra pseudoumbilicus var amplus is identified

holocene precipitation in the coastal temperate rainforest complex of southern british columbia canada abstract pollen data from 69 surface samples from vancouver island canada were used to develop a ratio index of precipitation douglas fir western hemlock index dwhi dwhi ratios were combined with interpolated estimates of mean annual precipitation to develop pollen based precipitation transfer functions the optimal regression model with a predictive range of 960 2600 mm was applied to 10 holocene lake sediment records distributed across a 150 km long coastal inland precipitation gradient predicted precipitation was spatially modelled in a geographic information system to examine the spatio temporal history of precipitation from this representative portion of the coastal temperate rainforest ctr complex of western north america the reconstructions show widespread early holocene dry conditions coupled with a steep east west precipitation gradient thereafter the modern precipitation gradient established 7000 years ago illustrating that the ctr complex has experienced marked short distance east west changes in precipitation in the past changes in the abundance of arboreal and non arboreal vegetation as well as fire disturbance are often concomitant with changes in holocene precipitation given the precipitation and vegetation history of the region conservation initiatives should focus on the moist outer coastal zone since it appears to have the greatest amount of resilience to perturbations in precipitation whereas monitoring programs for signs of climate change should be initiated in central and eastern areas as they appear sensitive to changes in the moisture regime

multi millennial streamflow dynamics in two forested watersheds on vancouver island canada abstract holocene streamflow was reconstructed for two rivers on vancouver island british columbia canada in 500 yr intervals the san juan river watershed is located on the wetter western side of the island whereas the koksilah river watershed is positioned on the drier eastern side both watersheds are forested to reconstruct streamflow temporal changes in precipitation estimated using a pollen based transfer function and evapotranspiration were established for each watershed and integrated into a water balance model calibrated using modern data while seasonal streamflow variability was maintained throughout the holocene with greater flow in the winter relative to the summer the amount of discharge has changed markedly through time lowest simulated flow occurred in the earliest holocene with low flow conditions beginning earlier in the year and extending later into the fall such conditions may have inhibited salmon from using many of the smaller rivers in the region streamflow steadily increased throughout the early holocene so that by ca 6500 cal yr before present near modern flow regimes were established as climate changes in the future the san juan and koksilah watersheds are expected to remain as pluvial hydroclimatic regimes though with an extended season of low flow similar to conditions during the early holocene

paleoclimate deduced from a multidisciplinary study of a half million year old stalagmite from rana northern norway a 7 cm thick flowstone sequence has been dated by extended uranium series techniques to less than 1 25 myr with a probable growth interval of 350 000 730 000 yr b p the time span is in accordance with paleomagnetic results revealing normal polarity for the whole sequence i e a depositional age of 730 000 yr b p oxygen isotope variations suggest deposition during three warm periods interrupted by two isotopically cold hiatuses characterized by bulk resolution and detrital laminae calculations suggest that climatic transitions may have involved a shift of 1 1 2 4 c in mean annual temperatures contemporary flooding of the cave due to adjacent glacier expansion provides evidence for the widely held view that speleothem deposition is halted by glacier proximity the flowstone matrix contained appreciable amounts of pollen pine birch as well as larger amounts of charcoal dust the pollen assemblage suggests a climate comparable with the present implying that norway has experienced at least three glacial interglacial transitions during the growth interval of the speleothem the warmer periods were characterized by a forest environment with ample evidence of fire

pollen from accurately dated speleothems supports alpine glacier low stands during the early holocene deciphering pollen assemblages from alpine speleothems holds potential to provide unique information about past vegetation in rapidly changing environments here we reconstruct subsurface aerosol transport at milchbach cave switzerland 1840 m asl based on the pollen content of two holocene stalagmites we demonstrate that pollen is chiefly associated with bacterially mediated calcite fabrics typical of a well ventilated cave system in contrast pollen is absent from columnar calcite fabrics confirming that hydrological transport is not a significant process for the incorporation of pollen into speleothems at milchbach cave our results support significant changes in the subsurface ventilation regime which can be associated with the waxing and waning of upper grindelwald glacier pollen assemblages obtained from six carbonate sub samples attest the presence of a mixed deciduous forest in the grindelwald valley during the early and middle holocene in agreement with coeval regional pollen records this study demonstrates that even small amounts of calcite 0 3 2 8 cm3 are capable of delivering pollen spectra representative of the original vegetation if sufficiently elevated deposition fluxes are provided

mg sr and sr isotope geochemistry of a belgian holocene speleothem implications for paleoclimate reconstructions in this study variations in mg ca sr ca and 87sr 86sr ratios in a holocene belgian speleothem cave secondary carbonate deposit are interpreted in terms of changes in water residence time and changes in weathering processes possibly induced by changes in west european climate a stalagmite from the pere noel cave belgium was dated with the tims u th method and was deposited between 13 and 2 ka bp the 1000 mg ca ratio varies between 4 9 and 26 and displays short term changes but no significant long term trend the 1000 sr ca ratio varies between 0 09 and 0 31 and displays both short term changes and a long term decreasing trend from 12 9 to 3 5 ka in parallel the sr isotopic composition of the speleothem decreases from 0 7090 at 12 9 ka to 0 7088 at 3 5 ka the sr isotope ratio is higher than expected from the overlying limestone 87sr 86sr 0 7081 which implies an external source of radiogenic sr most probably from a silicate phase short term and long term changes in mg ca sr ca as well as long term changes of 87sr 86sr ratios can be explained by changes in the dissolution and precipitation processes of the host limestone these processes are controlled by changes in water residence times linked to changes in the water excess precipitation minus evapo transpiration c 2000 elsevier science b v all rights reserved

the airfall pollen budget of archaeologically important caves creswell crags england this paper investigates fundamental taphonomic issues for palynologists working on archaeologically important cave deposits the extent to which the pollen and spores reaching the accumulating sediment surfaces reflect the vegetation in cave entrances or reflect the more regional environments beyond the caves the study sites were four adjacent caves at creswell crags near sheffield england church hole dog hole c7 and robin hood s cave the compositions of the pollen and spore assemblages caught in the caves over a one year period were shown to reflect the vegetation in the cave mouths and the wider area beyond the ap nap ratio in the assemblages trapped in the caves corresponded with the proportions of woodland and open ground within a 5 km radius of the site comparatively high representations of fern spores in caves were a persistent feature and were attributed to the interactions of habitat distribution and taphonomic processes i the abundance of ferns in cave mouths and ii the effects produced by a combination of diurnal micro climatological process interacting with diurnal variations in spore production in the cave entrance in two caves church hole cave and dog hole cave the numbers of grains caught appeared to decline with increasing distance into the cave in cave c7 the numbers of grains caught increased towards the back of the cave the number of grains caught appears to be a principal determinant of the number of plant taxa identified there were no clear relationships between the presence of a flue effect in the cave and the presence of an increase or a decrease in the number of grains caught with changing distance into the caves it is concluded that as long as account is taken of the particular topographic microclimatic and taphonomic conditions in these caves it is possible to infer the character of the vegetation beyond their confines from the airfall pollen and spores trapped with them at the cave sediment surface

cave minerals of the world 2nd edition by carol hill and paolo forti national speleological society huntsville al 463 p isbn number 1 879961 07 5 70 00 think about all of those spectacular displays of mineral crystals that grace the world s mineral museums a great many of the large faceted crystals grew in some sort of cavity over long periods of time such mineral crystals are discovered in vugs pockets and cavities exposed in mines and quarries the conditions under which they were found are very different from the conditions under which they grew the fluids from which they grew are long gone a challenge for mineralogists to deduce from the surviving clues of trace elements isotopes and fluid inclusions now consider a cave it also is a cavity maintaining conditions of constant temperature water vapor pressure and carbon dioxide pressure for long periods of time this is also an environment where minerals can grow but in the case of many caves human observers can watch the growth process in progress some cave minerals appear as large faceted crystals some are nondescript crusts of little beauty but fascinating mineralogy most have formed from flowing dripping and seeping water and thus take on shapes dictated by the idiosyncrasies of the moving water such mineral deposits are known as speleothems stalactites stalagmites flowstone and a host of more intricate shapes hill and forti illustrate speleothems with some spectacular color photographs the authors have solicited contributions from cave photographers all over the world and without exception the

black carbon pollution of speleothems by fine urban aerosols in tourist caves speleothems in the karst caves of south korea which receive many visitors are losing their aesthetic appeal due to black coloring mineralogical textural and chemical analyses were conducted on the speleothems to discover the cause of the discoloration an abrupt color change from the natural color seen in the inner zones to the black color of the outer zones suggests that pollution commenced just after the opening of caves to visitors and has continued since then the main mineral compositions of both the outer black and the inner layers are the same but the concentration of non carbonate carbon is much higher in the black layers than in the inner layers electron microscopy showed that chain like agglomerates ca 0 2 1 1 m diameter of sub micrometer carbon spheres ca 0 02 0 05 m diameter are absent from the inner layer but present in the black layer as well as in the cave aerosol on the basis of their sub micrometer size agglomeration pattern and composition the carbon spheres and their agglomerates are considered to originate mostly from automobile exhaust they are presumed to have been carried into the caves by visitors from urban environments and then deposited on the surface of growing speleothems protection of speleothems from discoloration requires control of these fine anthropogenic aerosols

pacific miocene carbon isotope stratigraphy using benthic foraminifera abstract seven miocene pacific ocean deep sea drilling project sites from four different water masses planktonic foraminiferal biogeographic regions have been correlated using 18 prominent carbon isotopic events defined in the benthic foraminiferal 13c records in dsdp site 289 the correlations are based on the assumption that there are global or at least pacific wide controls on the 13c of deep water hco3 each of the individual 13c records is correlated to site 289 based on the shape of the curves in a manner analogous to that used to correlate sea floor magnetic anomaly patterns the results of this correlation experiment confirm that planktonic foraminiferal biostratigraphy and carbon isotopic stratigraphy are consistent within the tropical surface water mass and precise to 100 000 years correlations between surface water masses suggest that the precision of foraminiferal biostratigraphy is on the average less than 200 000 years due to the lack of cosmopolitan marker species and diachronism of species occurrences carbon isotope stratigraphy used in conjunction with biostratigraphy has the potential to provide an easily utilized globally applicable correlation tool with an interregional precision of 100 000 years or better as more continuous and undisturbed deep sea sections become available as a result of the hydraulic piston coring program

aragonite calcite speleothems identifying original and diagenetic features despite the increasing use of speleothems as high resolution archives of past climate proxies few efforts have been made to improve understanding of diagenetic pathways affecting this material and to assess the degree of postdepositional transformation of initial features including associated geochemical signatures to provide criteria for distinguishing primary spelean growth history and secondary spelean diagenetic history features this study documents a process based approach combining mineralogical textural and geochemical data at different scales to characterize various diagenetic processes undergone by aragonite and calcite speleothems from the pont de ratz cave herault s france results show that the initial precipitation of carbonate minerals forming the stalagmites vadose precipitation is represented alternatively by aragonite and calcite and consists of two types of primary aragonite and a primary columnar calcite four different types of growth interruption and inclusion horizons are evident and attest to the discontinuous growth of stalagmites in this cave postdepositional diagenetic processes include void filling calcite cementation selective dissolution of either aragonite or calcite and recrystallization recrystallization processes include 1 textural change of original aragonite precipitates isomineralogical recrystallization and 2 two distinct types of aragonite to calcite recrystallization these results highlight the diversity of potential synformational and postformational processes controlling the formation and evolution of speleothems and their impact on the geochemical properties of the primary and secondary carbonate phases and the potential importance in paleoclimatic interpretation

a 53 year seasonally resolved oxygen and carbon isotope record from a modern gibraltar speleothem reconstructed drip water and relationship to local precipitation abstract the response of a climate proxy against measured temperature rainfall and atmospheric circulation patterns at sub annual resolution is the ultimate test of proxy fidelity but very few data exist showing the level of correspondence between speleothem climate proxies and the instrumental climate record cave sites on the gibraltar peninsula provide a unique opportunity to calibrate speleothem climate proxies with the longest known available precipitation isotopes and instrumental records an actively growing speleothem sampled from new st michaels cave in 2004 is composed of paired laminae consisting of light columnar calcite and a darker microsparitic calcite stable isotope analysis of samples micromilled in 100 m steps at the equivalent of bi monthly intervals reveals fabric correlated annual cycles in carbon isotopes oxygen isotopes and trace elements responding to seasonal changes in cave microclimate hydrology and ventilation patterns calcite 13 c values reach a minimum in the light columnar fabric and evidence from trace element behaviour and cave monitoring indicates that this grows under cave winter conditions of highest p co 2 whereas the dark microsparitic calcite characterised by elevated 13 c and 18 o values grows under low summer p co 2 conditions drip water 13 c dic reaches a minimum in march april at which time the attenuated 18 o signal becomes most representative of winter precipitation an age model based on cycle counting and the position of the 14 c bomb carbon spike yields a precisely dated winter oxygen isotope proxy of cave seepage water for comparison with the gnip and instrumental climate record for gibraltar the 18 o characteristics of calcite deposited from drip water representing winter precipitation for each year can be derived from the seasonally resolved record and allows reconstruction of the 18 o drip water representing winter precipitation for each year from 1951 2004 these data show an encouraging level of correspondence r 2 0 47 with the 18 o of rainfall falling each year between october and march and on a decadal scale the 18 o of reconstructed winter drip water mirrors secular change in mean winter temperatures

evidence for solar influence in a holocene speleothem record pere noel cave se belgium abstract we present a decadal centennial scale holocene climate record based on trace elements contents from a 65 cm stalagmite from belgian pere noel cave pere noel pn stalagmite covers the last 12 7 ka according to u th dating high spatial resolution measurements of trace elements sr ba and mg were done by laser ablation inductively coupled plasma mass spectrometry la icp ms trace elements profiles were interpreted as environmental and climate changes in the han sur lesse region power spectrum estimators and continuous wavelet transform were applied on trace elements time series to detect any statistically significant periodicities in the pn stalagmite spectral analyses reveal decadal to millennial periodicities i e 68 75 133 136 198 209 291 358 404 602 912 1029 and 2365 2670 yr in the speleothem record results were compared to reconstructed sunspot number data to determine whether solar signal is presents in pn speleothem the occurrence of significant solar periodicities i e cycles of gleissberg de vries unnamed 500 years eddy and hallstatt supports for an impact of solar forcing on pn speleothem trace element contents moreover several intervals of significant rapid winter change were detected during the holocene at 10 3 9 3 9 5 around 8 2 6 4 6 2 4 7 4 5 and around 2 7 ka bp those intervals are similar to the cold winter events evidenced in different natural paleoclimate archives suggesting common climate forcing mechanisms related to changes in solar irradiance

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

cave aerosols distribution and contribution to speleothem geochemistry there is developing interest in cave aerosols due to the increasing awareness of their impacts on the cave environment and speleothem this paper provides the first attempt to synthesize the issues processes of cave aerosol introduction transport deposition distribution and incorporation are explored and reviewed from existing literature key issues of specific aerosol processes of distribution and production as well as cave location and morphology effects are highlighted through the presentation of preliminary monitoring data this study identifies the strong relationship between cave ventilation cave aerosols and their consequent spatial distribution the contribution of cave aerosol deposition to speleothem geochemistry is modelled and evaluated using a mass balance framework as an example speleothem trace element data from obir cave austria are compared with aerosol inputs to evaluate their significance the mass balance study demonstrates that generally under normal continuous growth and environmental conditions aerosol deposition will be of only minor importance however it highlights specific scenarios in which aerosol contributions will be significant speleothem hiatuses or slow growth high aerosol deposition and secondary microbiological feedback

morphogenesis and microstructure of concrete derived calthemites distributions of calcareous calthemite deposits have been widely documented but depositional processes and the architecture of their internal fabrics are not well understood these concrete degradation products from a case study area in western canada have external morphologies comparable to calcite speleothems formed in natural limestone caves but the internal microstructural architecture and mineralogy are markedly different the mineralogy consists of mostly calcite with secondary halite and minor percentages of trona and portlandite a novel morphogenetic model explains depositional processes resulting in calcareous crusts that follow fractures of an overlying concrete surface and how sufficient structural integrity provided by the internal architecture supports attachment areas of tubular soda straws interiors of these multi cm crusts consist of curvilinear calcite laminae arrayed as sub parallel walls compartmentalizing water gas interfaces along variously interconnected conduits and basin form chambers overall porosities of 40 60 or more are prevalent in contrast to 1 associated with externally similar drapery form crusts deposited within natural limestone caves several calcite fabrics new to calthemite deposits are described including dendritic shrubs that coalesce into concentric growth rings along central canals of soda straws

holocene fluctuations of a meromictic lake in southern british columbia abstract holocene deposits of mahoney lake a meromictic saline lake located in a closed basin in the semi arid okanagan valley contain evidence of frequent and marked changes in lake depth up to 12 m 10014c yr probably caused by short term changes in effective precipitation we studied a 5 45 m long core comprising a basal layer of inorganic mud overlain by a succession of layers of calcareous laminated and nonlaminated organic mud marl and sand we used mazama tephra to adjust nine radiocarbon ages for the hardwater effect meromixis developed ca 900014c yr b p and the lake has been episodically meromictic for about half the time since because of close linkages between sediments and depositional environments in meromictic and saline lakes we infer that laminated sediments indicate meromictic conditions and high lake levels ca 12 m water depth whereas thick marl layers and nonlaminated sediments indicate nonmeromictic conditions and thus low lake levels

calcium carbonate precipitation mediated by bacterial carbonic anhydrase in a karst cave crystal morphology and stable isotopic fractionation abstract stable oxygen 18o and carbon 13c isotopes of speleothems are widely used as important proxies for paleoclimatic and paleoenvironment reconstructions however the influence of microbial activity on carbon and oxygen isotope fractionation during speleothem precipitation remains unclear bacterial carbonic anhydrase ca can promote calcium carbonate precipitation to catalyze the mutual transformation between co2 and hco3 ca producing bacteria lysinibacillus sp strain lhxy2 were separated in the xueyu cave chongqing sw china and used in laboratory and cave in situ models to investigate their influence on the precipitation amount mineral components crystal morphology and carbon and oxygen isotope fractionation of caco3 a ca activity gradient was applied in the laboratory model by considering various ca inhibitor acetazolamide az concentrations which showed that the ca activity could substantially enhance precipitation alter the mineral components and morphology and reduce the 13c and 18o values of the caco3 formed most importantly the laboratory and in situ model results revealed approximately 7 and 1 4 13c shifts respectively compared to the bacteria free model results which indicated that microbial driven carbon isotopic fractionation can cause great uncertainties in paleoclimate and paleoenvironment reconstructions

mid to late holocene climate change an overview the last 6000 years are of particular interest to the understanding of the earth system because the boundary conditions of the climate system did not change dramatically in comparison to larger glacial interglacial changes and because abundant detailed regional palaeoclimatic proxy records cover this period we use selected proxy based reconstructions of different climate variables together with state of the art time series of natural forcings orbital variations solar activity variations large tropical volcanic eruptions land cover and greenhouse gases underpinned by results from general circulation models gcms and earth system models of intermediate complexity emics to establish a comprehensive explanatory framework for climate changes from the mid holocene mh to pre industrial time the redistribution of solar energy due to orbital forcing on a millennial timescale was the cause of a progressive southward shift of the northern hemisphere nh summer position of the intertropical convergence zone itcz this was accompanied by a pronounced weakening of the monsoon systems in africa and asia and increasing dryness and desertification on both continents the associated summertime cooling of the nh combined with changing temperature gradients in the world oceans likely led to an increasing amplitude of the el nin o southern oscillation enso and possibly increasingly negative north atlantic oscillation nao indices up to the beginning of the last millennium on decadal to multi century timescales a worldwide coincidence between solar irradiance minima tropical volcanic eruptions and decadal to multi century scale cooling events was not found however reconstructions show that widespread decadal to multi century scale cooling events accompanied by advances of mountain glaciers occurred in the nh e g in scandinavia and the european alps this occurred namely during the little ice age lia between ad w1350 and 1850 when the lower summer insolation in the nh due to orbital forcing coincided with solar activity minima and several strong tropical volcanic eruptions the role of orbital forcing in the nh cooling the southward itcz shift and the desertifi cation of the sahara are supported by numerous model simulations other simulations have suggested that the fingerprint of solar activity variations should be strongest in the tropics but there is also evidence that changes in the ocean heat transport took place during the lia at high northern latitudes with possible additional implications for climates of the southern hemisphere sh

late quaternary climatic change on the american north pacific coast temporal changes in solar radiation caused by variations in the earth s orbit figure prominently in current quaternary climate theory1 4 experimental design of atmospheric circulation models emphasizes the importance of solar radiation in the heating of interglacial land and ocean surfaces at different seasons of the year whereby monsoon type circulation seasonal shifting of regional cyclonic and anticyclonic centres develops while during glacial ages seasonality is greatly modified by the influence of ice sheets5 7 we investigated the late quaternary climate of the north pacific where according to modelling solar radiation in the early holocene at the time of the summer solstice is high and in the late holocene is relatively low we compared quantitative temperature and precipitation estimates from southern alaska obtained by application of transfer functions to fossil pollen records with estimates from western washington8 and southern british columbia9 data extending over 10 000 years show a broadly consistent pattern of climatic change in general agreement with predicted variations in solar radiation and their effect on atmospheric circulation and seasonal duration of pressure systems over the north pacific ocean in the early holocene as monsoon type circulation became established with melting of glaciers the subtropical north pacific anticyclone annually regulated climate for a longer period at higher latitudes than at present so that warmth and dryness high summer radiation increased in southern alaska the aleutian low pressure centre locus of cyclonic storm activity intensified during the late holocene resulting in colder and more humid coastal climate low summer radiation over much of the year and increased frequency of glacier growth in the cordillera

diatom pollen and chemical evidence of postglacial climatic change at big lake south central british columbia canada abstract postglacial climatic conditions were inferred from cores taken from big lake in southern british columbia low concentrations of nonarboreal pollen and pigments near the base of the core suggest that initial conditions were cool increases in both aquatic and terrestrial production suggest warmer and moister conditions until 8500 cal yr b p hyposaline diatom assemblages increases in nonarboreal pollen and increased concentrations of pigments suggest the onset of arid conditions from 8500 to 7500 cal yr b p slightly less arid conditions are inferred from 7500 until 6660 cal yr b p based on the diatoms small increases and greater variability in biogenic silica and pigments and higher percentages of arboreal pollen at 6600 cal yr b p changes in diatoms pigments biogenic silica and organic matter suggest that big lake became fresh deep and eutrophic until 3600 cal yr b p when water levels and nutrients decreased slightly our paleoclimatic inferences are similar to pollen based studies until 6600 cal yr b p however unlike these studies our multiple lines of evidence from big lake imply large changes in effective moisture since 6000 cal yr b p

a 963 year reconstruction of summer jja stream flow in the white river arkansas usa from tree rings an average of three baldcypress taxodium distichum ring width chronologies was used to recon struct total summer jja mean daily flow of the white river at clarendon arkansas for years 1023 1985 a quadratic transformation of the tree ring data accounted for 68 r 2 adjusted for degrees of freedom lost when regressed against total summer flow 1931 1985 the distribution of the quadratic reconstruction matched the gauged distribution much better than a simple linear model which only accounted for 62 of the variance the model was validated by comparing regression estimates against independent data years with summer flow below the 25th percentile occur nonrandomly i e they tend to cluster in both the reconstructed and gauged data hydrologic regimes have apparently varied considerably in the past on annual to century time scales with extended dry and wet periods that exceeded anything in the modern record the frequency of both wet and dry extremes has varied considerably over the last millennium the eleventh through thirteenth cen turies were not analysed due to reduced replication but the well replicated fourteenth and twentieth centuries both have large numbers of extremes the twentieth century appears to have more extreme low flows than the previous centuries and also to have a large number of high flows the practical consequences for society of variation in extremes and persistence of low flows may be considerable climatic change or anthropogenic changes to the watershed e g widespread upland clearing for agriculture and logging of bottomland forests may be responsible for the change in hydrologic regime during the twentieth century

petrology and geochemistry of annually laminated stalagmites from an alpine cave obir austria seasonal cave physiology calcite stalagmites from obir an alpine 1100 m altitude perennially wet cave were studied using optical and electron backscatter diffraction petrology bulk icp ms analysis and microanalysis by ion microprobe and micro x ray fluorescence using synchrotron radiation drip water penetrates 70 m through triassic limestones with some pb zn mineralization to the chamber saulenhalle where the stalagmites were collected and with which we compared drip water compositions however the cave is also characterized by strong seasonal ventilation leading to low pco2 in winter all samples display autumnal event lamination defined by a narrow optically visible zone with trace element enrichments within which synchrotron studies have resolved micron scale enrichments of pb and zn crystallite scale 10 m lateral trace element variations reflect alternate smooth faces and rough crystal edges induced by high zn content seasonal falls in sulphate s and increase in 13c can be associated with the winter ventilation the elemental covariations support the transport of pb zn p f br and i by organic colloids but final depositions from aerosols rather than dripwater should be considered the chemical variations are powerful expressions of seasonal cave physiology but the study points to important gaps in our understanding of colloidal element transport in ventilated caves

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

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

medieval drought in the upper colorado river basin 1 new tree ring records of ring width from remnant preserved wood are analyzed to extend the record of reconstructed annual flows of the colorado river at lee ferry into the medieval climate anomaly when epic droughts are hypothesized from other paleoclimatic evidence to have affected various parts of western north america the most extreme low frequency feature of the new reconstruction covering a d 762 2005 is a hydrologic drought in the mid 1100s the drought is characterized by a decrease of more than 15 in mean annual flow averaged over 25 years and by the absence of high annual flows over a longer period of about six decades the drought is consistent in timing with dry conditions inferred from tree ring data in the great basin and colorado plateau but regional differences in intensity emphasize the importance of basin specific paleoclimatic data in quantifying likely effects of drought on water supply

black carbon records in chinese loess plateau over the last two glacial cycles and implications for paleofires abstract to study the temporal and spatial changes in paleofires over the chinese loess plateau black carbon concentrations were analyzed on the loess paleosol samples from three sections along a north south transect using the orbitally tuned time scales of the sections the black carbon mass sedimentation rates bcmsr were calculated results show that in the last two glacial cycles the bcmsr values in glacial periods are 2 3 times higher than in interglacial periods and the bcmsr variability has a relatively strong precession associated 23 ky period suggesting that the glacial cold dry climate conditions were apt to induce natural fires over the loess plateau comparison of the bcmsr records among the three loess sections demonstrates that natural fire occurrence was much more intensive and frequent in the northern loess plateau than in the southern part coinciding with the previous conclusion that the northern plateau has experienced a drier climate regime in both glacial and interglacial periods the substantial increase in bcmsr of the upper s0 relative to the lower s0 at lingtai and weinan indicates that human activities have exerted a significant influence on fire regimes in the middle and southern loess plateau during late holocene due to the relatively intensive agricultural usage of land

the impact of air mass circulation dynamics on late holocene paleoclimate in northwestern north america paleoclimate records from northern british columbia southwestern yukon and adjacent alaska suggest that late holocene climate may have been influenced by specific air mass circulation dynamics the aleutian lowpressure index alpi is a measure of sea level pressure fluctuations in the pacific northwest associated with the aleutian low al pressure system in this study we show that the al has a strong influence on historical climate change in the study area and explore the relationships between alpi polarity and changes in late holocene paleoclimate records analyses of weather station data in the study area indicate positive correlations r 0 63 between mean wintertime december march temperature and alpi values total wintertime snowfall accumulation and total precipitation show moderate and weak negative correlations respectively a late holocene increase in exotic western hemlock tsuga heterophylla pollen has been observed in regional paleoclimate studies a sustained positive alpi phase during the late holocene is considered as a causative mechanism under such conditions warm maritime air masses would more frequently penetrate inland potentially resulting in eastward pollen transfer enhanced growing conditions at coastal sites and an increase eastwards in the range limit of these species this study indicates that apparent conflicts in the timing and magnitude of late holocene climate change may be the result of a strong regional climate forcing mechanism that exhibits both temporal and geographical variation r 2002 elsevier science ltd and inqua all rights reserved