chemical weathering rates of silicate dominated lithological classes and associated liberation rates of phosphorus on the japanese archipelago implications for global scale analysis abstract lithology is an important characteristic of the terrestrial surface whose properties influence chemical weathering rates specifically non silicate minerals may contribute significantly to the weathering derived fluxes from silicate dominated lithological classes the japanese archipelago consists of predominantly silicate dominated lithologies with a high proportion of volcanics however the spatially explicit representation of chemical weathering rates remains difficult for such a large region because many controlling factors on chemical weathering rates are correlated with each other due to the spatial heterogeneity of lithology a multi lithological model approach to estimate spatially explicit chemical weathering rates for unmonitored areas is applied here to achieve this hydrochemical data of 381 catchments are used to train a set of models recognizing the contribution of a variety of proposed factors influencing chemical silicate rock weathering rates csrwr cations plus dissolved silica flux the monitored catchments cover 44 of the japanese archipelago cation chemical weathering rates excluding si are linearly correlated with csrwr and show outliers if basic volcanics or pyroclastic flows are present due to increased silica release rates lithology and runoff are identified as the strongest predictors for chemical weathering rates temperature and gradient of slope are of less relevance for the regional scale prediction while further proposed factors like soil properties or land cover are not identified as major predictors latter findings are partly attributed to geodata quality low variability of parameter values as well as spatial correlations of proposed controlling factors with lithology or runoff the calculated average csrwr of the archipelago is 25 t km 2 a 1 and ranges from 5 9 to 107 t km 2 a 1 in monitored catchments weathering rates per lithological class as a function of runoff can be grouped into three classes a pyroclastic flows showing the highest chemical weathering rates b alluvial deposits mixed sediments and basic to intermediate volcanics with medium rates and c metamorphics siliciclastic sediments acid volcanics acid plutonics and unconsolidated sediments other than alluvial deposits showing the lowest rates the recognition of lithogenic sulfur would add 9 7 to csrwr of considered catchments results suggest that the lithological classes acid volcanics and unconsolidated sediments contribute above average to the sulfur fluxes possible biases of this observation are discussed the contribution of ca fluxes from non silicate calcic minerals named ca excess ca fluxes in addition to silicate ca fluxes is about 10 of the csrwr on average and is attributed by a wide value range the calculated ratio ca excess to total ca fluxes from chemical weathering averages around 62 75 56 83 and 84 for the lithological classes acid plutonics metamorphics siliciclastic sediments mixed sediments and acid volcanics respectively this suggests a major ca contribution from non silicate calcic minerals for these lithological classes phosphorus release from rocks due to chemical weathering is estimated to be between 1 kg p km 2 a 1 and 390 kg p km 2 a 1 the p release patterns in dependence of runoff per lithological class are different from csrwrs due to differences of applied p content in rocks the identified spatial p release patterns suggest that the consideration of dynamic and spatially resolved p release rates by chemical weathering might improve ecosystem studies later findings may be of importance for analysing the influence of p release from rocks on the climate system via ecosystem functioning on geological time scales a first application of the p release model to the global scale suggests an annual release of 1 6 mt p 13 8 kg p km 1 a 1 by chemical weathering of silicate dominated lithological classes excluding carbonate sedimentary rocks

a systematic comparison of obsidian hydration measurements the first application of micro image with secondary ion mass spectrometry to the prehistoric obsidian abstract archaeologists have long used obsidian hydration dating method to give chronometric dates for obsidian artifacts models using these equations independently employ different measurement systems which are based on rim thicknesses determined by optical microscope and hydrogen depths measured by secondary ion mass spectrometry sims respectively although the inconsistency of both measurements has been reported firstly this paper describes a systematic comparison that was done on optical rim thicknesses and hydrogen depths by means of an isotope microscope which provides micro imaging with sims depth profiles of hydrogen were precisely obtained from the spots where optical measurements were taken on the archaeological obsidian flakes from two distinctive cultural horizons older upper paleolithic younger initial jomon in the stratified open air site of jozuka in southern kyushu japan secondarily using the measurements of hydrogen depths that are the most consistent to the measurements of optical thicknesses the estimated hydration rate of the holocene initial jomon is slower than that of the late pleistocene upper paleolithic implying that the difference in hydration rates was due to the difference of intrinsic water content of obsidian and or obsidian geochemistry an application of micro imaging with sims to measure hydrogen depths on obsidian shows promise as a tool for improving the practice of hydration dating and evaluating local climatic condition

how landscape heterogeneity governs stream water concentration discharge behavior in carbonate terrains konza prairie usa abstract mounting evidence suggests ecosystem changes that alter subsurface water fluxes and carbon dioxide concentrations in carbonate terrains may drive measurable changes in chemical weathering rates stream water chemistry and flow path evolution on human timescales we test this idea by exploring if the encroachment of woody vegetation into grasslands in a carbonate terrain landscape at the konza prairie ks usa has resulted in differences in landscape stream connectivity and thus the behavior of stream water solutes woody encroachment up to 60 cover at konza has been observed on watersheds particularly those that experience a fire return interval of four years or greater we focus on three headwater catchments two grassland and one woody encroached and a downstream confluence and analyze stream water discharge and chemistry major anions cations and dissolved nutrients measured from 2015 to 2016 we observe that the woody encroached watershed exhibits a greater area normalized solute flux and greater degree of chemodynamic behavior for most geogenic species compared to the less encroached grassland watersheds the downstream confluence exhibits the most chemostatic behavior for these same solutes compared to the low order watersheds we interpret the chemodynamic behavior of the woody encroached watersheds to arise from a greater diversity of flow paths and solute sources that contribute to this stream end member mixing analysis emma supports this hypothesis but also indicates a possible missing end member which we interpret to be solutes likely derived from clay weathering along limestone mudstone boundaries we invoke differences in rooting systems between grass and woody species to explain the differences in flow paths and solute generation between these headwater sites given that they sit adjacent to each other dissect the same nearly horizontal dip 0 1 0 21 nw lithologic units and experience the same climate if these processes hold true at other sites then the globally observed encroachment of woody vegetation into grasslands may deepen flow paths and enhance chemical weathering fluxes from ecosystems and over long time periods alter the trajectory of soil development and landscape evolution

lake stratigraphy implies an 80 000 yr delayed melting of buried dead ice in northern russia sediment cores from lakes kormovoye and oshkoty in the glaciated region of the pechora lowland northern russia reveal sediment gravity flow deposits overlain by lacustrine mud and gyttja the sediments were deposited mainly during melting of buried glacier ice beneath the lakes in lake kormovoye differential melting of dead ice caused the lake bottom to subside at different places at different times resulting in sedimentation and erosion occurring only some few metres apart and at shifting locations as further melting caused inversion of the lake bottom basal radiocarbon dates from the two lakes ranging between 13 and 9 ka match with basal dates from other lakes in the pechora lowland as well as melting of ice wedges this indicates that buried glacier ice has survived for ca 80 000 years from the last glaciation of this area at 90 ka until about 13 ka when a warmer climate caused melting of permafrost and buried glacier ice forming numerous lakes and a fresh looking glacial landscape copyright 2003 john wiley sons ltd

bicarbonate fluxes and co2 consumption by chemical weathering on the japanese archipelago application of a multi lithological model framework abstract prediction of co 2 consumption by chemical weathering is important to understand the global carbon cycle and island arcs are assumed to contribute significantly to the transfer of atmospheric soil co 2 to the oceans previous work established empirical functions for bicarbonate flux and co 2 consumption in dependence of runoff for five to six lithological classes these functions were applied in global studies however it has remained uncertain if improvements can be achieved by considering further factors or by an enhanced lithological classification scheme this study applies a new lithological map of japan with an enhanced lithological classification a hydrochemical data set representing 382 catchments covering 44 4 of the japanese archipelago and a multi lithological model approach to predict bicarbonate fluxes and co 2 consumption by chemical weathering because of significant carbonate contents in sediments different from carbonate sedimentary rocks acid plutonics and metamorphics firstly a bicarbonate flux model approach is established and secondly silicate and carbonate co 2 consumption is estimated based on the geochemical composition of rocks in accordance with previous studies on the catchment scale the most important factors controlling bicarbonate fluxes are lithology and runoff the anion ratio hco 3 so 4 2 cl is identified as the third most important predictor because anion sources and anion composition of river water have a great effect on bicarbonate concentrations and last but not least potential predictors such as gradient of slope temperature and physical erosion explain some part of the observed bicarbonate flux variation these potential predictors have been discussed in literature but quantification of the effects of these factors remains difficult due to their correlation with runoff and lithology however all tested models reproduce a total of observed bicarbonate fluxes within 10 on the regional scale including the simplest model which recognizes only lithology and runoff as predictors model results suggest that bicarbonate flux from the japanese archipelago is about 6 61 t c km 2 a 1 and co 2 consumption by chemical weathering is about 6 05 t c km 2 a 1 91 6 of bicarbonate flux this co 2 consumption rate is 3 2 times above the global average rate the silicate to carbonate co 2 consumption ratio is comparatively high it amounts to 9 9 which is above the global value the latter one being 1 to 1 5 carbonate sedimentary rocks contribute only 1 3 to bicarbonate fluxes due to their low areal proportion 0 2 acid volcanic rocks va show the lowest bicarbonate fluxes on average while basic and intermediate volcanics vb as well as pyroclastics py are in the range of the japanese average value the carbonate weathering contribution to bicarbonate fluxes from mixed sediments siliciclastic sediments metamorphics and acid plutonics is estimated to be 69 2 23 3 63 4 and 24 8 respectively only an average carbonate co 2 consumption per lithological class is calculated because no function based on typical predictors could be established to calculate carbonate weathering contribution to silicate dominated lithological classes this can be attributed to large spatial differences in carbonate content in rocks and to corresponding contributions to bicarbonatefluxes in the following results are compared to bicarbonate flux models of previous studies and identified differences are discussed in conclusion recognition of carbonate abundance in silicate dominated lithological classes including trace calcite is important to calculate silicate carbonate co 2 consumption ratios presented results are relevant for studies modelling co 2 consumption by chemical weathering in context of the global c cycle

obsidian hydration dating accuracy and resolution limitations imposed by intrinsic water variability obsidian hydration dating typically yields a range of ages for a single chronometric measurement even after controlling for source chemistry and effective hydration temperature previously published data suggest that this range is due to hydration rate variations caused by variability in the concentration of intrinsic water and specifically hydroxyl ions in the obsidian such variability exists within any given obsidian source and even within any particular specimen this paper analyzes the effect on age estimates of intrinsic water variability and concludes that if a controlled sample of obsidian yields a range of ages there is no way to tell whether the range is due to long site use or to variations in hydroxyl concentration at present there is no robust and cost effective protocol for measuring hydroxyl concentration suggested guidelines for obsidian hydration dating are developed using a case study these findings do not invalidate obsidian hydration as a chronometric technique but they do suggest limits to the temporal resolution achievable

sources of weathering derived solutes in two granitic catchments with contrasting forest growth chemical weathering is one of the controlling factors for landform evolution here we present deductions about the location and rate of chemical weathering within catchments based on chemical observations of soil water groundwater springs and streams in two granitic catchments with contrasting forest growth conditions forested and non vegetated and soil development the two catchments are located in the tanakami mountains of central japan and share the same climate in both catchments sio2 and na are the dominant weathering derived solutes in the first order stream using hydrological evidence the contribution to the sio2 and na fluxes from soil and bedrock were partitioned despite the difference in mean soil depth net fluxes of sio2 and na from the soil profile do not differ much between the two catchments suggesting low levels of easily weatherable minerals in the forest soil net sio2 and na fluxes from bedrock are about three times greater in the forested catchment than in the bare catchment and these differences contribute largely to the difference in net fluxes from the catchments net fluxes of sio2 and na from the forested catchment are about twice those from the bare catchment part of this increase may be related to the greater proton production in forested catchment consequently about 60 to 70 of the net sio2 and na fluxes from the non vegetated catchment and 70 to 90 from the forested catchment are derived from bedrock suggesting that the contribution of bedrock to the export of these weathering products increased with forest growth and soil formation copyright 2004 john wiley sons ltd

holocene pollen stratigraphy indicating climatic and tree line changes derived from a peat section at ortino in the pechora lowland northern russia this study presents the results of pollen analysis and radiocarbon dates of a peat section from ortino in the pechora lowland in northern russia a pollen stratigraphy is provided for at least the last 9200 years and it provides a basis for the reconstruction of the vegetational and mire history in the northernmost part of european russia conifer stomata content was recorded as a complement to pollen studies to achieve a better resolution of tree line fluctuations the onset of holocene warming initiated a vegetation succession that started first with herb dominated tundra vegetation and later with herb shrub tundra combined pollen and stomata evidence suggests that picea accompanied by betula spp spread to ortino soon after 9000 14c yr bp trees and a climate warmer than at present persisted until c 3000 14c yr bp when forests disappeared and modern dwarf shrub tundra vegetation developed

obsidian hydration at high elevation archaic quarrying at the chivay source southern peru we examine obsidian hydration as a means to date archaeological sites at high elevation in the central andes and in particular quarry sites that are difficult to date by radiocarbon means the chivay obsidian source lies in a volcanic depression above the colca valley in arequipa peru 71 5355 s 15 6423 e at 4950 masl we compare obsidian hydration readings from one quarry and two workshop locations ninety one flakes from the quarry pit and 61 and 33 flakes from the workshops were analyzed for hydration bands of these 68 from the quarry and 54 and 33 respectively from the workshops produced at least one culturally meaningful hydration band as expected obsidian appears to hydrate slowly at this high elevation yet variation in hydration readings is low within stratigraphic contexts suggesting relatively narrow windows of knapping activities in each excavation level a small number of radiocarbon dates allow us to develop a preliminary hydration rate for chivay obsidian in this high elevation location hydration data indicate that intensive quarrying began by 3800 cal bc and stopped ca 2300 cal bc by contrast the two workshops appear to have been deposited 2900 and 1200 cal bc and 2700 and 2400 cal bc the data are consistent with an uptick in obsidian use by at least the terminal archaic period 2011 elsevier ltd all rights reserved

late quaternary ice sheet history of northern eurasia the maximum limits of the eurasian ice sheets during four glaciations have been reconstructed 1 the late saalian 140 ka 2 the early weichselian 100 80 ka 3 the middle weichselian 60 50 ka and 4 the late weichselian 25 15 ka the reconstructed ice limits are based on satellite data and aerial photographs combined with geological field investigations in russia and siberia and with marine seismic and sediment core data the barents kara ice sheet got progressively smaller during each glaciation whereas the dimensions of the scandinavian ice sheet increased during the last ice age the barents kara ice sheet attained its maximum size as early as 90 80 000 years ago when the ice front reached far onto the continent a regrowth of the ice sheets occurred during the early middle weichselian culminating about 60 50 000 years ago during the late weichselian the barents kara ice sheet did not reach the mainland east of the kanin peninsula with the exception of the nw fringe of taimyr a numerical ice sheet model forced by global sea level and solar changes was run through the full weichselian glacial cycle the modeling results are roughly compatible with the geological record of ice growth but the model underpredicts the glaciations in the eurasian arctic during the early and middle weichselian one reason for this is that the climate in the eurasian arctic was not as dry then as during the late weichselian glacial maximum

climate related river activity at the weichselian holocene transition a comparative study of the warta and maas rivers huvial systems from the dutch and polish lowlands are compared for their evolution during the weichselian deglaciation period in both regions the pleniglacial braided river pattern changed to a meandering pattern in the beginning of the lateglacial several transitional stages between braided and high sinuosity meandering systems have been recognized a difference in fluvial activity is found during the younger dryas when the maas transformed to a braided pattern while the warta maintained its meandering pattern phases of erosion and aggradation are more or less synchronous in the different river basins but their intensity may differ greatly the major characteristics of the fluvial systems are obviously a response to the general climatic evolution and related to changes in vegetation the regional differences are of minor importance and can be explained by site specific factors threshold values within the latter factors define the changes in river dynamics

procedures used for luminescence dating of sediments abstract an account of the procedures for thermoluminescence tl and optically stimulated luminescence osl dating of sediments used at the nordic laboratory for luminescence dating is given the topics discussed include sampling sample preparation separation of quartz and feldspars using heavy liquids dose rate estimation and methods for estimating the equivalent dose special attention is paid to the partial bleach tl technique of mejdahl 1988 which appears to give reliable results for partially bleached sediments optically stimulated luminescence dating using stimulation by infra red ir and green light has been taken up and especially added dose methods using stimulation by ir or green light have been tried with some success some sources of error are discussed including the adverse effect of shallow traps

climatic vs tectonic controls on peat accretion in non marine setting an example from the žacleř formation yeadonian bolsovian in the intra sudetic basin czech republic abstract the acle coalfield in the western part of the intra sudetic basin is an example of coal accumulation in an alluvial valley deposited under a long term 3 m y stable tectonic regime with climatic oscillations possibly operating on several time scales the resulting sedimentary record about 600 m thick encompasses about 60 coal bearing cycles formed in a relatively small and localized part of the valley whereas elsewhere a higher clastic input and or lower rate of subsidence resulted in deposition of strata with very little coal available data suggest that tectonics produced accommodation for sediments and via changes in topography and or size of the source area affected the volume and dispersal patterns of clastic material transported to the depocentre areas with long term tectonic stability were suitable places for recognition of climatic signals in the sedimentary record modified by the intensity of local clastic input climatic fluctuations generated coal bearing cycles probably through a variable intensity of precipitation which affected the density of vegetation cover across the landscape along with evaporation and groundwater table these factors influenced the intensity of chemical weathering and hence regulated the volume and composition of clastics delivered to the depocentre this in turn resulted in alternation of short periods of bedload dominated deposition during the seasonally dry part of the cycle with periods of dominantly suspended load and organic peat deposition during the more humid everwet part of the cycle estimated duration of the basic cycles 46 k y approximates the orbitally driven axial tilt cyclicity basic cycles are arranged into two larger scale cyclic patterns lasting for 270 k y and 1 5 m y respectively which broadly correspond with the timing of glacial maxima and minima inferred from high latitude glacial deposits of gondwanan basins all the coals of the acle coalfield display similar petrographic composition dominated by collotelinite and field observations as well as detailed petrographic study show that they formed in planar rheotrophic peat swamps where long lasting peat accretion was episodically interrupted only by major floods on a century to millennial scale

luminescence dating of archaeological materials using a new technique based on single aliquot measurements abstract a dating method based on single aliquot luminescence dose determination was applied to quartz and feldspars from heated archaeological materials the problem of changes of sensitivity to radiation resulting from signal erasure in regeneration measurements was studied in some detail and a new method based on single aliquot regeneration measurements within an added dose framework which appears to eliminate the problem of sensitivity change is proposed preliminary dating results mainly using quartz obtained with the new method are presented

water percolating behavior indicated by the water chemistry within a decomposed granite slope central japan abstract monitoring rainfall discharge amount and the chemistry of water from just beneath the groundwater table yielded a conceptual model of water percolation behavior within a decomposed granite slope in central japan providing a clue to evaluate a landslide hazard potential by rainstorms when rainfall is strong enough more than about 50 mm a day in this case air pressure in the vadose zone probably increases temporarily because of the downward movement of a wetting front pushing down the water of the capillary fringe the capillary water has sio2 concentrations controlled by the precipitation of cristobalite the water is rich in ca which is supplied from plagioclase with sio2 after the pushing down of the capillary water rainwater with soil water in the unsaturated zone reaches the groundwater surface the cation concentrations in the unsaturated soil water and the capillary water are affected by ion exchange

predicting natural base flow stream water chemistry in the western united states 1 robust predictions of stream solute concentrations expected under natural reference conditions would help establish more realistic water quality standards and improve stream ecological assessments models predicting solute concentrations from environmental factors would also help identify the relative importance of different factors that influence water chemistry although data are available describing the major factors controlling water chemistry i e geology climate atmospheric deposition soils vegetation topography geologic maps do not adequately convey how rocks vary in their chemical and physical properties we addressed this issue by associating rock chemical and physical properties with geological map units to produce continuous maps of percentages of cao mgo s uniaxial compressive strength and hydraulic conductivity for western united states lithologies we used catchment summaries of these geologic properties and other environmental factors to develop multiple linear regression lr and random forest rf models to predict base flow electrical conductivity ec acid neutralization capacity anc ca mg and so4 models were derived from observations at 1414 reference quality streams rf models were superior to lr models explaining 71 of the variance in ec 61 in anc 92 in ca 58 in mg and 74 in so4 when assessed with independent observations the root mean square error for predictions on validation sites were all temperature precipitation soil atmospheric deposition vegetation amount of rock water contact topography

erosion and weathering fluxes in granitic basins the example of the strengbach catchment vosges massif eastern france abstract this work reports on regular observations of the suspended sediment and bedload flux at the outlet of the granitic strengbach catchment 0 8 km over the period 2004 2010 along with the analysis of the dissolved load the data set allows a first determination of the physical erosion flux 3 3 t km 2 yr 1 exported out of the strengbach watershed and how it compares to the chemical weathering flux of basic cations the data indicate that the erosion rate carried by the bedload 1 7 t km 2 yr 1 can reach one third of the total erosion rate 5 t km 2 yr 1 in the strengbach watershed the accuracy of these rates is estimated to be 20 the study also indicates that the estimated values for the net annual weathering flux calculated for the watershed can differ by a factor of two or more depending on the corrections applied and the assumptions retained for the watershed s functioning from an uncorrected weathering flux of basic cations of 4 76 t km 2 yr 1 to an atmosphere corrected weathering flux of 2 t km 2 yr 1 for the period 2004 2010 the weathering budgets determined for the strengbach catchment fit the general trend defined between the weathering rate and runoff for other granitic watersheds this suggests that the anthropogenic impact due to acid perturbation or forest management has a relatively weak influence on the weathering intensity within the watershed the relationship between weathering and erosion rates determined for the strengbach catchment does not significantly differ from those established for other previously studied granitoid catchments

the fluvial cycle at cold warm cold transitions in lowland regions a refinement of theory abstract a previously established non linear theory of river cyclicity as a response to climate change states that short phases of fluvial instability occur both at the transition from relatively warm temperate to cold periglacial and from relatively cold to warm periods such instability typically starts with vertical erosion successively followed by sedimentary fill of the erosive scar in spite of frequent confirmation of this theory by geomorphological reconstructions a few problems arise first there are fewer incision phases than climatic transitions secondly remnants of erosion at cold warm transitions are scarce in contrast to obvious erosion relics at warm cold transitions furthermore it appears that the incision style is strikingly different at both kinds of climatic transitions similarly the long stable phases are also expressed in terms of different floodplain development in cold and warm periods these arguments require a modification of the general non linear theory at the transition from relatively temperate to colder conditions rivers transformed gradually from a regular low energy single channel course to a periodically high energy multi channel type the latter braided type is characterized by intense lateral movement rather than by deep vertical erosion this results in a well expressed morphology of wide extensive floodplains and terraces in contrast the linear and constrained meandering channels incise with small width depth ratio and build floodplains of limited lateral extent consequences are twofold 1 the spatial limitation of the deeply incised meandering valleys at the beginning of warm periods counts against their recognition 2 relatively strong lateral migration of the braided rivers removes most traces of previous meandering systems which contrasts with the limited lateral activity of confined meandering channels it means that in a warm cold warm alternation generally only one phase of vertical erosion is preserved the one that is caused by the high energy braided river at the start of the cold period

the plateau method for dating partially bleached sediments by thermoluminescence abstract the plateau method for dating sediments that have been incompletely bleached prior to deposition is described by exposing aliquots of a sample to sunlight for different periods of time a range of residual values is obtained and combined with the additive dose or the regeneration technique to yield a series of paleodoses the correct paleodose is taken as that for which the longest plateau in a plot of paleodose vs temperature is obtained

the svalbard barents sea ice sheet historical current and future perspectives abstract the history of research on the late quaternary svalbard barents sea ice sheet mirrors the developments of ideas and the shifts of paradigms in glacial theory over the past 150 years since the onset of scientific research there in the early 19th century svalbard has been a natural laboratory where ideas and concepts have been tested and played an important but rarely acknowledged role in the break through of the ice age theory in the 1870 s the history of how the scientific perception of the svalbard barents sea ice sheet developed in the mid 20th century also tells a story of how a combination of fairly scattered and often contradictory observational data and through both deductive and inductive reasoning could outline a major ice sheet that had left but few tangible fingerprints since the 1980 s with increased terrestrial stratigraphical data ever more marine geological evidence and better chronological control of glacial events our perception of the svalbard barents sea ice sheet has changed the first reconstructions depicted it as a static concentric single domed ice sheet with ice flowing from an ice divide over the central northern barents sea that expanded and declined in response to large scale late quaternary climate fluctuations and which was more or less in tune with other major northern hemisphere ice sheets we now increasingly perceive it as a very dynamic multidomed ice sheet controlled by climate fluctuations relative sea level change as well as subglacial topography substrate properties and basal temperature in this respect the svalbard barents sea ice sheet will increasingly hold the key for understanding the dynamics and processes of how marine based ice sheets build up and decay

a gis model for predicting wetland habitat in the great basin at the pleistocene holocene transition and implications for paleoindian archaeology the great basin s earliest inhabitants relied heavily on wetland systems that underwent a great decline culminating in the early holocene in this paper we derive expectations for regional paleoindian archaeology by modeling the distribution and disappearance of lake margin wetland habitats basin geomorphology and hydrology are used to predict change through time in the occurrence of these habitats fifty two pluvial lakes are drained from their pleistocene highstands by computer simulation using gis and the changing extent of associated wetlands is quantified we find that as these lakes declined to shallow depths many experienced corresponding increases in wetland habitat prior to complete desiccation thus while the total area of wetland habitat in the region could have maintained some stability through this process the number of available basin wetlands would have dropped relatively rapidly as smaller basins completely dried up the model therefore implies that those lakes that disappeared earliest should hold the archaeological signatures most restricted to early paleoindian times assemblages associated with these lakes should also reflect higher forager mobility corresponding with the greater number of basin wetlands available we find preliminary support for the model in several archaeological cases but emphasize the need for further basin specific research to clarify the nature and timing of wetland habitat loss and the extent to which this was a constraint for paleoindian populations

an archaeologically validated protocol for computing obsidian hydration rates from laboratory data this paper reports the computation of hydration rate for topaz mountain obsidian from laboratory data and a comparison with archaeological data from a well dated site camels back cave in western utah topaz mountain obsidian is found to be slow hydrating with a rate of 0 071 0 021 yr at an effective hydration temperature of 16 01 c this rate agrees with a rate developed from archaeological data from camels back cave within 6 activation energy of topaz mountain obsidian is 10370 544 k and its diffusion constant is 1 87 9 13 1013 2 yr both of which are independent of temperature its intra source variability in hydration rate is very low cv 0 01 implying a low variability in intrinsic water we present a model of chemical erosion which shows why earlier laboratory determined rates were incorrect and discuss the implications of our findings on the determination of experimentally derived rates in obsidian hydration dating

the margin of the last barents kara ice sheet at markhida northern russia the markhida moraine is a broad zone of ice marginal landforms and deposits running e w across the pechora lowland in northern russia it was formed along the southern margin of an ice sheet advancing onto the coast from the kara sea previous researchers grosswald 1980 1983 1994a grosswald et al 1974 concluded that the moraine was formed during a readvance of the barents kara ice sheet after 9000 14c yr b p this conclusion was based on the occurrence of deformed lacustrine sediments dated 9000 to 10 000 14c yr b p between two presumed basal tills in the type section at markhida a reinvestigation of the section by the authors revealed only one basal till overlain by lacustrine sediments and diamictons yielding radiocarbon dates between 9000 and 10 000 14c yr b p luminescence dating from the sand underlying the till gave middle weichselian ages deformation structures and fabric in the sediments overlying the till solely reflect gravity driven processes not glaciotectonic deformation as claimed by previous investigators we conclude that most of these sediments were finally deposited during very slow retarded melting of a large body of buried glacier ice and the underlying permafrost thus the markhida moraine as an ice marginal feature was formed prior to 10 000 14c yr b p probably during the late weichselian but possibly as early as the middle weichselian

accuracy of obsidian hydration dating based on obsidian radiocarbon association and optical microscopy abstract most archaeologists using obsidian hydration dating ohd in the united states develop hydration rates from association of obsidian hydration rims with dates based on radiocarbon subsequently using the rate for chronometric analysis the overall accuracy of the process has never been quantified this paper reports an accuracy analysis in which sources of uncertainty are defined and modeled and their effects quantified a monte carlo simulation is used to quantify errors from rate development while uncertainties in age resulting from chronometric analysis are calculated analytically for typical ranges of error values hydration rate errors of 5 or less are achievable in the absence of systematic errors with errors of chronometric age estimates 20 30 or less

timescales climate and river development abstract in the long term glacial interglacial sequences river development follows general climatic evolution however at the scale of one cold warm cycle it appears that the geomorphological effect of river activity is best expressed at times of climatic change such periods of pronounced fluvial action last only a short time in more detail the internal evolution in a drainage basin after a climatic event results in a delayed response of the morphology and sedimentation pattern finally on the shortest timescale local thresholds may play a decisive role in the reactions of river systems it is concluded that the relation between fluvial development and climate is not a simple one but is fundamentally dependant on the timescale

predicting riverine dissolved silica fluxes to coastal zones from a hyperactive region and analysis of their first order controls silicate weathering and resulting transport of dissolved matter influence the global carbon cycle in two ways first by the uptake of atmospheric soil co2 and second by providing the oceanic ecosystems via the fluvial systems with the nutrient dissolved silica dsi previous work suggests that regions dominated by volcanics are hyperactive or even hot spots concerning dsi mobilization here we present a new approach for predicting dsi fluxes to coastal zones emphasizing first order controlling factors lithology runoff relief land cover and temperature this approach is applied to the japanese archipelago a region characterized by a high percentage of volcanics 29 1 of surface area the presented dsi flux model is based on data of 516 catchments covering approximately 56 7 of the area of the japanese archipelago the spatial distribution of lithology one of the most important first order controls is taken from a new high resolution map of japan results show that the japanese archipelago is a hyperactive region with a dsi yield 6 6 times higher than the world average of 3 3 t sio2 km 2 a 1 but with large regional variations approximately 10 of its area exceeds 10 times the world average dsi yield slope constitutes another important controlling factor on dsi fluxes besides lithology and runoff and can exceed the influence of runoff on dsi yields even though the monitored area on the japanese archipelago stretches from about 31 to 46 n temperature is not identified as a significant first order model variable this may be due to the fact that slope runoff and lithology are correlated with temperature due to regional settings of the archipelago and temperature information is substituted to a certain extent by these factors land cover data also do not improve the prediction model this may partly be attributed to misinterpreted land cover information from satellite images implications of results for earth system and global carbon cycle modeling are discussed

signature of the last shelf centered glaciation at a key section in the pechora basin arctic russia the vastiansky kon is the largest exposure of quaternary deposits in the pechora lowland northern russia morphologically the site belongs to the so called markhida moraine a complex east west trending zone of ice marginal landforms deposited by the kara sea ice sheet during the last glaciation the site exhibits a succession of sediments more than 100 m thick that according to previous studies covers the interval from the end of the elsterian to the beginning of the holocene unfortunately both the strong glaciotectonic deformation of the sedimentary succession and few absolute dates have made the chronological interpretation of the section difficult the present paper reviews previous studies of the site published in russian and presents the results of a reinvestigation focusing on the post eemian stratigraphy a marine eemian clay more than 8 m thick is overlain erosionally by 20 m of fluvial deposits of late eemain or early weichselian age the fluvial succession is overlain by a till and a marine clay which according to one interpretation may represent an early or middle weichselian advance of the kara ice sheet followed by a transgression the clay shows a transition into 15 m of estuarine and fluvial sediments overlain by more than 12 m of tundra floodplain deposits the whole succession has been upthrusted glaciotectonically by the last ice advance which deposited a more than 12 m thick till on top of the section based on a number of subtill radiocarbon age estimates from the site in the range 25 32 ka bp the youngest ice advance is considered to be of late weichselian age although a middle weichselian age cannot be excluded 1998 john wiley sons ltd

the significance of obsidian hydration dating in assessing the integrity of holocene midden hokkaido northern japan abstract since its novel invention in 1960 obsidian hydration dating is now recognized as the chronometric method to give dates of archaeological sites based on measurements of hydration rim thickness contrary to the increased awareness of various factors that affect hydration rates and reliability in measurements the question whether and the extent to which the validity in the rim thickness measurements corresponds to the interested event has been less discussed here validity of obsidian hydration dates that designate event of human site occupations is discussed in terms of site integrity of the early jomon midden in the holocene site of ocharasenai och hokkaido northern japan expected integrity of the midden evidently left by prehistoric hunter gatherers is tested through a comparison of microscopically measured average rim thicknesses between the primarily extracted specimens and those chosen after assessing the validity no statistical difference in estimated hydration dates between these two groups supports high integrity of the midden the estimated date for the early jomon occupation at the och is 4388 4942 bp fallen into the end of middle holocene results of the present examination indicate that obsidian hydration dating will aid to understand site formation processes

trace elements and environmental isotopes as tracers of surface water groundwater interaction a case study at xin an karst water system shanxi province northern china in this case study silica concentration oxygen and strontium isotopes of water samples were used to study surface water groundwater interaction at the xin an karst water system the silica concentration in rain water is commonly less than 1 mg l in the areas around the south tributary of the zhuozhang river silica concentrations in the groundwater in quaternary aquifers range between 4 04 and 7 66 mg l while that of the surface water varies from 1 49 to 6 9 mg l silica concentrations of most surface water samples increase with tds indicating the effect of groundwater recharge on river water chemistry on the contour map of silica concentration of groundwater in quaternary aquifers samples located close to surface water often have lower silica concentrations as a result of surface water recharge both overland flow and surface water have impact on karst water according to our hydrogeochemical study of stable oxygen isotope sr isotope and strontium contents calculation results of three end member mixing model show that the contribution of karst water surface water and overland flow water is 45 28 and 27 respectively