geochemical evolution of groundwater in the cambrian vendian aquifer system of the baltic basin abstract the shallowly buried marginal part of the cambrian vendian confined aquifer system of the baltic basin is characterised by fresh and low 18 o composition water whereas the deeply settled parts of the aquifer are characterized by typical na ca cl basinal brines spatial variation in water geochemistry and stable isotope composition suggests mixing origin of the diluted water of three end members glacial melt water of the weichselian ice age 115 000 10 000 bp na ca cl composition basin brine and modern meteoric water the mixing has occurred in two stages first the intrusion and mixing of isotopically depleted glacial waters with basinal brines occurred during the pleistocene glacial periods when the subglacial melt water with high hydraulic gradient penetrated into the aquifer the second stage of mixing takes place nowadays by intrusion of meteoric waters the freshened water at the northern margin of the basin has acquired a partial equilibrium with the weakly cemented rock matrix of the aquifer

a tree ring based reconstruction of summer relative humidity variability in eastern mongolian plateau and its associations with the pacific and indian oceans a regional chronology rc based on tree ring width data at two sites was developed for the southern hulun buir sandy land a marginal area of the eastern mongolian plateau china this chronology significantly and positively correlated with the relative humidity from the previous december to september except in may the highest correlation of the rc with the mean june august relative humidity suggested that the growth of pinus sylvestris var mongolica strongly reflects seasonal moisture conditions consequently the variation in the mean june august relative humidity was reconstructed for the reliable time period of 1835 2013 41 6 of the variance occurred during the calibration period of 1953 2012 similar patterns of drought and pluvial fluctuations were found in other tree ring based moisture reconstructions our reconstruction implied that the characteristics of regional hydroclimatic variations such as the drought and low humidity of the late 1990s to 2000s were not unusual from the long term perspective as suggested by the hydrological records obtained from tree ring material spectrum analyses results and significant spatial correlations of our relative humidity reconstruction with the sea surface temperature sst in the eastern equatorial pacific ocean and tropical indian ocean implied close linkages between moisture in the eastern mongolian plateau and remote oceans when the sst related to the el nino southern oscillation was high low the intensity of the indian summer monsoon at the northern extremities weakened strengthened thus moisture decreased i e the relative humidity was low in north china and in our study area the low land sea thermal contrast between asia and the indian ocean due to the enhanced ssts in the tropical indian ocean also influenced the strength of the moisture transfer via the indian summer monsoon thereby reducing the moisture variations in the eastern mongolian plateau

detecting dryness and wetness signals from tree rings in shenyang northeast china article i nfo for drought and flood forecasting it is critical that we understand regional rainfall patterns as well as their potential underlying forcings particularly in urban regions with greater long term anthropogenic influences compared to rural areas to achieve this three chinese pine pinus tabulaeformis tree ring width chronologies were developed from the metropolitan suburban and rural sites near shenyang city of northeast china and used to study regional dryness and wetness variability in the past 232 yr january may precipitation 1771 2002 was successfully reconstructed from the tree rings although urban factors caused a slightly reduced response of the tree rings to precipitation our reconstruction captures certain local rainfall variability and dryness wetness signals such as three unusually dry decades 1920s 1850s and 1960s an unusually dry half century 1850 1899 and some significant cycles 2 8 yr and 20 yr associated with them it also reveals a relatively equal number of dry wet events 38 79 wet years versus 35 78 dry years and a recent drying trend our study also indicates the feasibility of using urban tree rings to reconstruct dry wet patterns in city environments

spatial and temporal patterns of variations in tree growth over the northeastern tibetan plateau during the period ad 1450 2001 we analyzed spatial and temporal growth variations of qilian junipers over the northeastern tibetan plateau tp during the period 1450 2001 by applying the empirical orthogonal function eof technique to seven moisture sensitive tree ring width chronologies the first three principal components together explain 78 21 of the total variance the first principal component pc1 accounts for 51 58 of the total variance and represents consistent tree growth variations in the northeastern tp the second eof mode reveals an opposite structure for the southern and northern parts of the northeastern tibetan plateau reflecting the effect of huge topography and associated atmospheric circulation on tree growth anomalies the third eof mode represents an opposite structure for the eastern and western parts of the northeastern tibetan plateau possibly indicating the influence of different branches of atmospheric circulation system in this area the eof analysis results of instrumental precipitation data resembl

resistivity imaging reveals complex pattern of saltwater intrusion along monterey coast abstract electrical resistivity tomography data were acquired along 40 km of the monterey bay coast in central california these data resulted in electrical resistivity images to depths of approximately 280 m b s l which were used to understand the distribution of freshwater and saltwater in the subsurface and factors controlling this distribution the resulting resistivity sections were interpreted in conjunction with existing data sets including well logs seismic reflection data geologic reports hydrologic reports and land use maps from the region interpretation of these data shows a complex pattern of saltwater intrusion resulting from geology pumping and recharge the resistivity profiles were used to identify geological flow conduits and barriers such as palaeo channels and faults localized saltwater intrusion from individual pumping wells infiltration zones of surface fresh and brackish water and regions showing improvements in water quality due to management actions the use of ert data for characterizing the subsurface in this region has led to an understanding of the spatial distribution of freshwater and saltwater at a level of detail unattainable with the previously deployed traditional well based salinity mapping and monitoring techniques alone significant spatial variability in the extent and geometry of intrusion observed in the acquired data highlights the importance of adopting continuous subsurface characterization methods such as this one

rare earth geochemistry of old phosphorites and probability of syngenetic precipitation and accumulation of phosphate1in memory of richard p sheldon1 abstract old vendian early cambrian phosphorites of the world demonstrate seawater like patterns in their rare earth element ree distributions but are depleted in heavy ree they also show a broad range of variation in total and elemental abundances primary bedded structureless phosphorites contain only 15 ppm total ree ree while granular pelletal varieties contain up to 650 ppm ree were incorporated into phosphate grains diagenetically during prolonged periods of transport and redeposition a higher surface mass ratio in pelletal phosphorites contributed to their enrichment in the ree s in primary bedded structureless phosphorites immediate burial of phosphate syngenetically precipitated and accumulated in situ at the sediment water interface prevented the later incorporation of the ree large deposits of vendian early cambrian phosphorites have originated by both processes primary bedded varieties occur in deeper water facies and granular phosphorites accumulated closer to the shore in terms of their ree geochemistry old granular phosphorites are almost indistinguishable from their phanerozoic counterparts indicating that both were deposited by the same mechanisms primary bedded structureless phosphorites were only deposited on a large scale at the beginning of the phanerozoic

a tree ring based precipitation reconstruction for the mohe region in the northern greater higgnan mountains china since ad 1724 abstract august july precipitation has been reconstructed back to ad 1724 for the mohe region in the northern greater higgnan mountains china using pinus sylvestris var mongolica tree ring width the reconstruction explains 39 of the variance in the precipitation observed from ad 1960 2008 some droughts noted in historical documents are precisely captured in our reconstruction wet periods occurred during the periods of ad 1734 1785 ad 1805 1830 ad 1863 1880 ad 1922 1961 and ad 1983 1998 while the periods of ad 1786 1804 ad 1831 1862 ad 1881 1921 and ad 1962 1982 were relatively dry power spectral and wavelet analyses demonstrated the existence of significant 24 yr 12 yr and 2 yr cycles of variability the results of the spatial correlations suggest that our reconstruction contains climatic signals for the southern stanovoy range and the northern greater higgnan mountains the positive correlations between the new reconstructed precipitation series and two precipitation reconstructions indicate that our precipitation reconstruction captures broad scale regional climatic variations a comparison between the weakening tendency of summer monsoon and the dry period of our reconstruction reveals that the annual precipitation in the mohe region is partly influenced by the east asian summer monsoon

rare earth element and sr nd isotope geochemistry of phosphatic rocks in neoproterozoic ediacaran doushantuo formation in zhangcunping section from western hubei province south china abstract phosphatic rocks are widely distributed in neoproterozoic ediacaran doushantuo formation in yangtze platform south china in this study we examined samples from the zhangcunping section in western hubei province with major element rare earth element ree and sr nd isotopic analyses on the phosphorites and the host dolostone rocks we employed an acid leaching method to separate the carbonate acetic acid leachable and phosphate hydrochloric acid leachable fractions in all the samples the geochemical differences between the different fractions can be recognized based on the p2o5 ree contents and sr nd isotopic characteristics the carbonate fractions in the rocks display low total ree concentrations with seawater like ree patterns super chondritic y ho ratios moderate negative ce anomalies and positive eu anomalies indicating these carbonates have retained the signatures of paleo seawater on the contrary the phosphate fractions display high total ree concentrations with hat shaped ree patterns generally lower y ho ratios weak negative ce anomalies and positive eu anomalies which may have recorded the features of diagenetic fluids negative ce anomalies and positive eu anomalies displayed in the carbonate fractions of the studied samples may also indicate the anoxic environments of ocean basins in south china during the deposition of the neoproterozoic ediacaran doushantuo formation a geochemical comparison between lower phosphorite layer and upper phosphorite layer indicates a greater degree of diagenesis occurred in the lower phosphorite layer than the upper phosphorite layer the negative end t values of the samples suggest continental crustal sources for the rees and the lower values in the phosphorite samples 6 9 to 6 0 than the dolostone samples 5 5 to 3 8 may suggest different processes for them and it is likely that the rees in the phosphorites have been modified by diagenetic fluids with ree contributions of pore fluids derived from the clastic silicates in the strata which generally have lower end t values whereas the dolostone took the rees from the ambient seawater mainly

origin and chemical evolution of formation waters from silurian devonian strata in the illinois basin usa abstract a suite of formation water samples from silurian devonian reservoirs in the illinois basin has been analyzed for major minor and trace element concentrations and for h o and sr isotopic compositions in order to interpret origin of salinity and geochemical evolution of brine compositions in this evaporite and shale poor cratonic basin although chloride concentrations range from 2000 to 137 000 mg l cl br ratios 291 18 are consistent with those of seawater or seawater evaporated short of halite saturation cl br 292 thus during silurian devonian time subaerially evaporated penesaline brine entered the subsurface where it was chemically modified through brine rock interactions cation br ratios and mineralogy of associated strata indicate that na and k were depleted through interaction with clay minerals ca was enriched and mg depleted by dolomitization and sr was enriched as a result of caco3 recrystallization and dolomitization although significant dilution of the modified brine with meteoric water is supported by d 18o covariance original marine waters have not been completely expelled from silurian devonian strata hydrogen and oxygen isotopes exhibit covariant relations with cation and anion concentrations implying that isotopic exchange between h2o and minerals has not greatly influenced the d 18o trend brine 87 sr 86 sr ratios range from 0 7092 to 0 7108 when these ratios are plotted versus 1 sr a two component mixing trend is suggested although sr concentrations have experienced local diagenetic modification a 87sr enriched fluid may have accompanied petroleum migration from new albany shales into adjacent silurian devonian carbonates where it mixed with remnant evaporated seawater this event probably preceded the influx of meteoric water as gdd and 18o are not correlated with sr isotopic compositions of formation waters

ruthenium variation in chromite from komatiites and komatiitic basalts a potential mineralogical indicator for nickel sulfide mineralization more than 390 chromite grains from komatiites and komatiitic basalts from the yilgarn craton of western australia and the finnish part of the fennoscandian shield were analyzed using in situ laser ablation inductively coupled plasma mass spectrometry la icp ms to identify ruthenium ru signatures in chromite associated with nickel sulfide bearing rocks results indicate a potential method to discriminate mineralized and barren komatiite and komatiitic basalt units based on ru concentrations in chromite and indicate potential for chromite to be used as a resistate indicator mineral in exploration for komatiite associated nickel sulfide deposits chromites from barren komatiites and komatiitic basalts display ru concentrations mostly between 150 and 600 ppb chromites from mineralized units have distinctly lower ru contents 150 ppb these results can be interpreted in terms of the much higher partition coefficient for ru into sulfide liquid compared to that of ru into chromite resulting in much lower ru concentrations in chromite where both chromite and sulfide liquid are present and competing for ru as a result the ru content of chromite can be used to determine if a komatiite melt equilibrated with a sulfide liquid during crystallization and therefore if a system and or sequence is prospective for nickel sulfide mineralization the strength of this method compared to previous whole rock exploration techniques derives from combining 1 the geochemical properties of a chalcophile element that records an ore forming process while being strongly immobile during postmagmatic processes with 2 the in situ analysis of a mineral that is generally preserved even in highly altered and mildly weathered komatiites and that is a common constituent of detrital heavy mineral samples chromite ru content has potential as a prospectivity indicator applicable to a wide range of media including bedrock laterites and detrital resistates heavy mineral samples

rare earth element and srnd isotope geochemistry of phosphate nodules from the lower cambrian niutitang formation nw hunan province south china abstract phosphate nodules are widely distributed in the early cambrian black shale sequence in yangtze platform south china in this study we carried out x ray diffraction major element rare earth element and sr nd isotopic studies on phosphate nodules from two pc c sections in hunan province south china two different types of phosphate nodules can be recognized based on ree and nd isotopic characteristics type 1 with seawater like ree patterns higher end t values and type 2 with hat shaped ree patterns and more negative end t values we suggest that the difference in ree patterns and nd isotopic compositions between the two types reflects changes in pore water geochemistry from seawater dominated towards diagenetic fluid dominated conditions during early diagenesis positive eu anomalies are displayed in most samples and are likely to record not only the anoxic environments but also the involvement of submarine exhalative hydrothermal fluids which prevailed in south china during early cambrian

mid to late holocene climate change in north central mongolia as recorded in the sediments of lake telmen abstract a record of climatic change has been reconstructed for the past 7110 calibrated calendar cal years for lake telmen mongolia based upon sedimentologic and geomorphic evidence from the lake watershed system lake telmen is a saline presently 4 g l 1 closed basin lake and is therefore sensitive to changes in effective moisture balance between 7110 and 6260 cal yr ago conditions in the lake telmen region were hyperarid and a small saline approximately 20 g l 1 lake was present increased effective moisture balance but still arid conditions prevailed between 6260 and 4390 cal yr ago since 4390 cal yr ago generally more humid conditions prevailed in the lake telmen region as the lake deepened a hypoxic hypolimnion became established below a well developed summer thermocline resulting in varved sediment accumulation since 4390 cal yr ago between about 2710 and 1260 cal yr ago a greater than present day effective moisture balance is recorded by a series of four lake highstand terraces sedimentologic profiles from lacustrine cores suggest an increase in effective moisture during the past approximately 680 cal yr

geochemistry and isotope chemistry of michigan basin brines devonian formations detailed chemical and isotope analysis of 87 formation waters collected from six devonian aged units in the michigan basin are presented and discussed in terms of the origin of the dissolved components and the water total dissolved solids in these waters range from 200 000 to 400 000mg 1 upper devonian formations produce dominantly nacacl brine while deeper formations produce canacl water ratios of cl br and na br along with divalent cation content mcl2 indicate that these brines are derived from evapo concentrated seawater other ion concentrations appear to be extensively modified from seawater values by water rock reactions the most important reactions are dolomitization which explains the ca content of the brines and reactions involving aluminosilicate minerals stable isotope 18o and d compositions indicate that water molecules in the deeper formations are derived from primary concentrated seawater isotope enrichment by exchange with carbonates and perhaps gypsum cannot be discounted isotope values indicate water in the upper devonian formations is a mixture of seawater brine diluted with meteoric derived water dilution has predominantly occurred in basin margins two scenarios are presented for the origin of the brines in the devonian formations 1 they originated when the devonian sediments and evaporites were first deposited or 2 they are residual brine liberated from the deeper devonian and possibly silurian salt deposits

recent eurasian river discharge to the arctic ocean in the context of longer term dendrohydrological records 1 mapped correlations between annual discharges ad 1938 1990 of the major eurasian rivers entering the arctic ocean severnaya dvina pechora ob yenisey lena and kolyma demonstrate a positive relationship between discharge and the palmer drought severity index pdsi within the individual basins and more distant areas the relationship between recent discharge and pdsi supports the application of dendrohydrological modeling to produce reconstructions of discharge extending back before the 20th century the dendrohydrologic models explain from 41 yenisey to 55 pechora of the observed variability of flow in the individual basins and 39 of the total combined discharge discharge reconstructions for the period ad 1800 1990 indicate that there is no long term monotonic trend toward higher discharge over the past 200 years reconstructed annual discharge for the individual rivers and the total discharge from all the rivers experienced in the 20th century are within the bounds of natural variability experienced over the past 200 years the s dvina pechora ob and kolyma reconstructions do display significant multidecadal variability in discharge similar to that observed in the north atlantic north pacific and northern hemisphere climatic parameters although the translation of such variability to the river discharges remains uncertain the presence of multidecadal variability makes it more difficult to detect or ascribe annual discharge changes that may be attributable to global warming

rare earth elements and stable isotope geochemistry of early cambrian chert phosphorite assemblages from the lower tal formation of the krol belt lesser himalaya india abstract the neoproterozoic cambrian transitional sequence in the mussoorie and garhwal hills of the lesser himalaya is represented by dolomites of the upper krol formation and chert phosphorite assemblages of the lowermost tal formation these rocks provide valuable information regarding the assumed existence of a stratified ocean during the terminal neoproterozoic and beginning of earliest cambrian nemakit daldynian the isotopic compositions of carbonate and organic carbon in the transition profile can be best interpreted as reflecting an oceanic anoxic event oae prior to the phase of early cambrian phosphate formation the chert phosphorite beds record negative ce and positive eu anomalies while ce is an important paleooceanic redox indicator eu is rather immobile under normal diagenetic conditions the observed eu anomaly is linked to the high ba content in these phosphorites and is indicative of an anoxic or sulfate reducing diagenetic environment the suggested stratification of the ocean during the late neoproterozoic and nemakit daldynian times would have been linked to the reduction of oxygen supply to the zone below the redoxcline causing 12 c and p rich organic matter previously produced in the photic zone to be trapped in large quantities within the deeper anoxic zone this would in turn increase the 13 c content of the water in the photic zone moreover in the deeper anoxic waters reduction of ce4 to ce3 would result in an enrichment of dissolved ce as ce3 upwelling of this anoxic bottom stratum would bring the 12 c and ce enriched waters back to the oxic marine realm however on entering the highly oxic productive zone the excess ce is expected to be removed from the water by oxidation to insoluble ce4 followed by precipitation or preferential scavenging due to these oxidation reactions the waters of the shallow oxic zone would tend to become rapidly depleted in ce in other words ocean mixing and upwelling during the early cambrian were ultimately responsible for the transport of 12 c p and ce to the oxic shelves sharp drops in both 13 c carb and 13 c org support the existence of oceanic anoxia followed by oceanic mixing at this juncture of earth history the large spread of the 34 s values of early diagenetic pyrites within the phosphorite bearing sequence in contrast to the limited spread of 13 c carb values suggests that phosphatisation took place under exclusively suboxic diagenetic non sulfate reducing condition and pyritisation began only when phosphate layers entered the zone of sulfate reduction

variation of hydrological regime with permafrost coverage over lena basin in siberia 1 we use monthly discharge and permafrost data to examine the relationship between discharge characteristics and basin permafrost coverage for the nested subbasins of the lena river in siberia there are similarity and variation in streamflow regimes over the basin the ratios of monthly maximum minimum flows directly reflect discharge regimes the ratios increase with drainage area from the headwaters to downstream within the lena basin this pattern is different from the nonpermafrost watersheds and it clearly reflects permafrost effect on regional hydrological regime there is a significant positive relationship between the ratio and basin permafrost coverage this relationship indicates that permafrost condition does not significantly affect streamflow regime over the low permafrost less than 40 regions and it strongly affects discharge regime for regions with high permafrost greater than 60 temperature and precipitation have similar patterns among the subbasins basin precipitation has little association with permafrost conditions and an indirect relation with river flow regimes there exists a good relation between the freezing index and permafrost extent over the basin indicating that cold climate leads to high coverage of permafrost this relation relates basin thermal condition with permafrost distribution the combination of the relations between temperature versus permafrost extent and permafrost extent versus flow ratio links temperature permafrost and flow regime over the lena basin over the aldan subbasin the maximum minimum discharge ratios significantly decrease during 1942 1998 due to increase in base flow this change is consistent in general with permafrost degradation over eastern siberia

geochronology geochemical and sr nd hf pb isotopic compositions of the granitoids in the yemaquan orefield east kunlun orogenic belt northern qinghai tibet plateau implications for magmatic fractional crystallization and sub solidus hydrothermal alteration abstract a general consensus has emerged that high field strength elements hfse can mobile to some extent in a hydrothermal fluid however there are hot debates on whether sub solidus hydrothermal alteration can lower the nb ta ratio in evolved melts in this study we present petrography geochronology and geochemistry of the barren and mineralized rocks in the yemaquan skarn iron deposit northern qinghai tibet plateau to probe magmatic hydrothermal transition the barren rocks consist of diorites granodiorites granites and syenogranites whereas the porphyritic granodiorites are associated with mineralization for an excellent consistency between the magmatic zircon u pb age 225 2 ma and the hydrothermal phlogopite 40 ar 39 ar age 225 1 5 ma the sr nd hf pb isotopic data demonstrate that the yemaquan granitoids are originated from a relatively homogenous enriched mantle with different degrees of crust contamination assimilation fractional crystallization afc trace elements signatures indicate that the porphyritic granodiorites related to mineralization display amphibole crystallization for high water contents whereas the barren granites have gone through biotite crystallization due to potassium enrichment by continuous upper crust contamination both of which are responsible for their nb ta ratios respectively modeling results suggest that a basaltic melt with nb ta ratio of 15 3 can reach a minimum nb ta ratio of 12 in the producing granodioritic melt by amphibole fractional crystallization based on partition coefficients of nb and ta between amphibole and melts from previous experiments this may explain the average nb ta ratio 13 7 of the barren granodiorites while it cannot account for the average nb ta ratio 8 4 of the mineralized porphyritic granodiorites and it is even lower than that of the granites 10 3 with biotite fractional crystallization exsolution of a magmatic hydrothermal fluid is inevitable when a water saturated magma emplaced in shallow crust leading to a transportation of certain chemical components from the magmatic melts to exsolved fluids because nb seems more mobile than ta in fluorine bearing fluids we contend that a preferentially transport nb over ta by sub solidus hydrothermal alteration can further lower the nb ta ratios of the mineralized porphyritic granodiorites which may also result in a broad range of hfse contents and their ratios in the altered porphyritic granodiorites formed in a post magmatic process

tree ring based precipitation reconstruction in the south slope of the middle qilian mountains northeastern tibetan plateau over the last millennium 1 a tree ring sabina przewalskii kom based millennial precipitation reconstruction on the south slope of the middle qilian mountains in the northeastern margin of tibetan plateau china was completed which explains 48 5 of the variance in the instrumental precipitation from 1958 to 2004 the long term precipitation variation patterns were confirmed on the basis of the duration magnitude and intensify of the multidecadal dry wet events there are several stronger multidecadal dry periods 1092 1172 1441 1517 and 1564 1730 whereas there is only one outstanding severe wet event of 1352 1440 the variations of the precipitation reconstruction are accordant with the glacier accumulation and dust contents of dunde ice core and also with the variations of the precipitation runoff palmer drought severity index and tree ring width series in the northeastern tibetan plateau the spatial extent of the great drought in the latter half of the 15th century also concentrated on the northeastern tibetan plateau the moisture variations in the northeastern tibetan plateau are synchronous over a large spatial and temporal range in multidecadal scale for the last millennium especially during dry periods wavelet analyses and comparisons with the minimal solar activity show that the precipitation variations for the last millennium may have some association with the solar activity on multidecadal to centennial scales

a la icp ms analysis of rare earth elements on phosphatic grains of the ediacaran doushantuo phosphorite at weng an south china implication for depositional conditions and diagenetic processes the ediacaran doushantuo formation at weng9an south china hosts well preserved phosphatized microfossils known as the weng9an biota a laser ablation icp ms analysis of rare earth element ree characteristics of the fossil bearing black phosphorite unit of the doushantuo formation at weng9an was conducted with the aim of unravelling the depositional conditions and diagenetic processes during formation of the phosphorites spherical phosphatized microfossils and phosphatic clasts were analysed and the ree data display middle ree mree enriched shale normalized ree patterns the spherical phosphatized microfossils show an increase in total ree contents ree from core to rim negative correlations between ree and the extent of mree enrichment over the other ree indicated by la n sm n yb n sm n are observed for analysed spots within individual phosphatic grains which may be due to complex diagenetic history of the phosphatic grains with fluctuations in ree sources and chemical parameters in a high energy shallow water environment being additional factors the la n yb n and la n sm n characteristics of the phosphatic grains suggest they were mostly influenced by early diagenetic alteration rather than late extensive recrystallization the negative ce anomalies in the samples suggest they formed under oxic bottom water conditions positive eu anomalies are present in all samples and are likely to reflect involvement of hydrothermal fluids rather than changes in redox conditions of porewater overall this study has major implications for phosphorites as important archives for the study of geochemical proxies the ediacaran period and also evolutionary changes

drought reconstruction in eastern hulun buir steppe china and its linkages to the sea surface temperatures in the pacific ocean abstract a tree ring width chronology covering the period 1780 2013 ad was developed from pinus sylvestris var mongolica for the eastern hulun buir steppe a region located on the edge of the eastern mongolian plateau china climate growth response analysis revealed drought stress to be the primary limiting factor for tree growth therefore the mean february july standardized precipitation evapotranspiration index spei was reconstructed over the period 1819 2013 where the reconstruction could account for 32 8 of the variance in the instrumental record over the calibration period 1953 2011 comparison with other tree ring based moisture sequences from nearby areas confirmed a high degree of confidence in our reconstruction severe drought intervals since the late 1970s in our study area consisted with the weakening east asian summer monsoon which modulating regional moisture conditions in semi arid zone over northern china drought variations in the study area significantly correlated with sea surface temperatures ssts in north pacific ocean suggesting a possible connection of regional hydroclimatic variations to the pacific decadal oscillation pdo the potential influence associated with el nino southern oscillation enso was primarily analyzed

diagenetic constraints on the use of cerium anomalies as palaeoseawater redox proxies an isotopic and ree study of cambrian phosphorites seawater rare earth element ree distributions show heavy ree enrichment and cerium depletion but these characteristics are only rarely found in ancient marine authigenic minerals such as carbonate fluorapatite and calcite this enigma may be due to changing ree distributions in seawater through time or to post depositional redistribution of ree differentiating between these two factors is however far from straightforward as their relative importance is likely to vary and evidence is often ambiguous in this article we present ree as well as strontium and sulphur isotope data for basal cambrian phosphorites of south china which confirm the emerging rule of thumb that granular phosphorites seldom reveal extreme departures from the seawater norm and tend to undergo therefore less diagenetic alteration of ree spectra than skeletal apatites and other phosphate types this study reveals stratigraphic trends in ce anomalies ce ce that could be taken to imply the preservation of a palaeoenvironmental signal however further investigation of our data shows that such trends in phosphorites can also be caused by post depositional alteration which tends to 1 increase ree contents 2 reverse ce depletion 3 alter eu anomalies and 4 concentrate preferentially the middle ree mree further alteration which may be due to weathering has led to hree depletion and positive la and y anomalies tetrad effect this is the first study where ceanom and phosphate bound sulphate s isotope values could be compared for one particular stratigraphic section which provides us with an additional tool for the interpretation of diagenetic redox conditions least altered phosphorites from meishucun that yield a strongly negative ceanom constrain early cambrian seawater 34s to about 33 we conclude that phosphorite ceanom primarily records variations in the local conditions of diagenesis while outlining some special cases in which diagenetic redox conditions may broadly reflect local bottom water redox conditions

tree ring δd as an indicator of asian monsoon intensity oxygen and hydrogen isotopic compositions of meteoric water are known to correlate with surface air temperature except in tropical areas this relationship has been described using a number of terms corresponding to specific observations such as latitude altitude and seasonal effects however these temperature effects do not seem to apply to precipitation in monsoonal areas of asia questions have been raised as to whether the isotopic composition of meteoric water can be used to reconstruct paleomonsoon intensity tree rings of two modern spruce trees picea meyeri and a 10 000 yr old timber picea jezoensis were analyzed for hydrogen isotopic composition on average the older tree is depleted in deuterium by 45 compared to the modern trees we attribute this isotopic depletion to the strength of summer monsoons which were more intense in the early holocene than at present although this study is not definitive it suggests that paleomonsoon intensity can be reconstructed by direct or proxy methods that yield the oxygen or hydrogen isotopic composition of meteoric water

streamflow reconstruction for the guxiang river eastern tien shan china linkages to the surrounding rivers of central asia based on the high correlation of the tree ring widths of larch and spruce trees with the actual streamflow variations the streamflow reconstruction of the guxiang river was developed for the period 1680 2009 with the low and high streamflow periods identified the reconstruction model accounts for 41 1 of the instrumental streamflow variance during the period 1957 2007 some significant cycles 18 1 8 1 3 8 2 9 2 6 2 4 and 2 1 years are found using the multi taper spectral analysis the significant correlations with the gridded spei dataset revealed that the streamflow reconstruction also represents the drought variation for a large area of the eastern tien shan the streamflow reconstruction of the guxiang river shows the decreasing trend since the 1970s and compares well with high and low streamflow periods of the selenge river previously estimated from tree ring records the synoptic climatology analysis reveals that there is the relationship between anomalous atmospheric circulation and extreme hydrological events in the guxiang river basin

a preliminary reconstruction of rainfall in north central china since a d 1600 from tree ring density and width abstract may june mj and april july aj precipitation at huashan in north central china has been reconstructed for the period a d 1600 to 1988 using tree ring density and width from pinus armandii mj precipitation based on ring width and maximum latewood density calibrated and cross validated against local instrumental data more strongly than aj precipitation based only on ring width a major drought was reconstructed for the mid and late 1920s confirmed by local documentary sources this drought culminating in 1929 was the most severe of the 389 yr period for mj and second most severe for aj after an event ending in 1683 neither reconstruction shows much spectral power at frequencies lower than 1 in 10 yr but both show concentrations of power between 2 1 and 2 7 yr and 3 5 to 9 yr there are significant correlations between the two reconstructions and a regional dryness wetness index dw based on documentary sources particularly at high frequencies these correlations are focused in the 7 6 to 7 3 3 8 to 3 6 and 2 5 yr periods using singular spectrum analysis quasiperiodic behavior with a period close to 7 2 yr was identified in the mj precipitation reconstruction and in the dw index based on documents

april september mean maximum temperature inferred from hailar pine pinus sylvestris var mongolica tree rings in the hulunbuir region inner mongolia back to 1868 ad two robust tree ring width chronologies were developed for the hulunbuir region inner mongolia northeast china both chronologies were significantly correlated with each other and were arithmetically averaged to build a regional chronology nbstd nbstd showed significant and negative correlations with the growing season maximum temperature from april to september based on this relationship the mean maximum temperature of april to september was reconstructed for the period from 1868 to 2008 the percentage of variance in the data explained by the reconstruction was 40 3 during the calibration period of 1953 2008 five severe warm events of two years or more were found in 1905 1909 1996 1997 2000 2001 2003 2005 and 2007 2008 five cold events occurred during the periods 1880 1881 1897 1900 1948 1949 1955 1960 and 1962 1964 on a decadal scale several warm intervals above the 1868 2008 mean were 1904 1913 1920 1933 1968 1975 and 1990 2003 cold intervals below the mean were 1893 1901 1950 1963 and 1976 1989 warmer events and intervals corresponded to dry periods colder events and intervals coincided with wet or moist conditions in and near the study region spatial correlation patterns revealed that our reconstruction represents a regional temperature and drought signal for the central and eastern mongolian plateau comparison with other tree ring based temperature reconstructions from surrounding areas provides a high degree of confidence in our reconstruction power spectrum and wavelet analyses suggest that the reconstructed mean maximum temperature variation may be related to large scale atmospheric oceanic variability such as the pacific decadal oscillation pdo el nino southern oscillation enso and sunspot activity c 2011 elsevier b v all rights reserved less

runoff to boreal lakes linked to land cover watershed morphology and permafrost thaw a 9 year isotope mass balance assessment stable isotopes of oxygen and hydrogen were measured in water samples collected annually from a representative suite of 50 lakes in northeastern alberta over a 9 year period and are interpreted using a steady state isotope mass balance model to determine water yield and runoff ratios for the lake watersheds and residence time of the lakes this isotopic perspective on hydrology of the region provides new insight into the role of land cover watershed morphometry climatic drivers and permafrost thaw on lakes bog cover permafrost and presence of thaw features in bogs are found to be the dominant hydrologic drivers although morphometric properties such as elevation lake area and drainage basin area are also influential in addition to quantifying the hydrologic fluxes the analysis establishes contrasting conditions in more southerly lakes located in the stony mountains and west of fort mcmurray as compared with more northerly sites in the birch mountains caribou mountains and northeast of fort mcmurray mainly because of contributions from thawing permafrost at the northerly sites distinct hydrologic conditions are also noted for shield systems north of lake athabasca where bogs and permafrost are absent while permafrost thaw is not directly labelled by oxygen and hydrogen isotope composition isotope mass balance calculations suggest that contributions of up to several hundred millimetres per year are occurring in 14 of the 50 lake watersheds under study several of these lakes have water yields in excess of precipitation in some years and regional groups of lakes display significant correlations between water yield and percentage of bogs that have collapsed copyright 2015 john wiley sons ltd

using 81kr and noble gases to characterize and date groundwater and brines in the baltic artesian basin on the one million year timescale abstract analyses for 81 kr and noble gases on groundwater from the deepest aquifer system of the baltic artesian basin bab were performed to determine groundwater ages and uncover the flow dynamics of the system on a timescale of several hundred thousand years we find that the system is controlled by mixing of three distinct water masses interglacial or recent meteoric water 18 o 10 4 with a poorly evolved chemical and noble gas signature glacial meltwater 18 o 18 with elevated noble gas concentrations and an old high salinity brine component 18 o 4 5 90 g cl l with strongly depleted atmospheric noble gas concentrations the 81 kr measurements are interpreted within this mixing framework to estimate the age of the end members deconvoluted 81 kr ages range from 300 ka to 1 3 ma for interglacial or recent meteoric water and glacial meltwater for the brine component ages exceed the dating range of the atta 3 instrument of 1 3 ma the radiogenic noble gas components 4 he and 40 ar are less conclusive but also support an age of 1 ma for the brine based on the chemical and noble gas concentrations and the dating results we conclude that the brine originates from evaporated seawater that has been modified by later water rock interaction as the obtained tracer ages cover several glacial cycles we discuss the impact of the glacial cycles on flow patterns in the studied aquifer system

extension of summer june august temperature records for northern inner mongolia 1715 2008 china using tree rings this paper presents a spatially and temporally improved reconstruction of mean summer june august temperature derived from tree ring width data of dahurian larch larix gmelinii rupr from the northern great xing an mountains northeast china three new chronologies were added to the original 2011 reconstruction and the reconstruction extended back to ad 1715 the reconstruction was generated using a simple linear regression method verified by independent meteorological data and accounts for 47 0 of the actual temperature variance during the common period 1957 2008 the reconstruction captures decadal and century scale regional temperature variability such as cold decades 1940s 1930s 1790s 1950s and 1850s warm decades 2000s 1870s 1750s 1980s and 1840s a cold half century ca 1750 1799 and a warm half century ca 1900 1949 it also reveals slightly higher frequency of cold years 20 4 than warm years 18 0 and a recent warming trend compared to the original 2011 reconstruction this reconstruction has lower inter annual temperature variability high explained variance and high representativeness of regional climate the reconstruction also correlates with the east asian monsoon and the pacific ocean signals and indicates the feasibility of using tree rings from high latitude northeast china to reconstruct summer temperature in permafrost forest environments

a 189 year tree ring record of drought for the dzungarian alatau arid central asia abstract mountain systems are the most important sources of water in arid central asia aca it is therefore essential to understand past cycles of droughts and pluvials and to explore how future cycles might influence the sustainable utilization of regional water resources the palmer drought severity index pdsi is a widely applied measure of dryness that can be reconstructed from tree rings here a schrenk spruce picea schrenkiana fisch et mey tree ring chronology was developed for the dzungarian alatau of aca correlation and response analysis indicated that the pdsi from previous july to current june was the principal factor limiting radial growth the chronology was used to reconstruct the pdsi of the past 189 years for the dzungarian alatau a calibration model for the period from 1950 to 2011 explains 42 6 or 41 7 after adjusting for the loss of degrees of freedom of the actual pdsi variance the reconstructed pdsi might be representative of drought conditions for most of aca because it captures severe drought events in the 1910s and 1940s that were widespread across aca the extreme drought years 1917 and 1945 are especially pronounced a decadal analysis shows that the five periods in which the pdsi trend increased were 1830 1840s 1880 1890s 1920 1930s 1950 1960s 1980 2000s the pdsi declined in the 1850 1870s the 1900 1910s the 1940s and the 1970s the pdsi in aca exhibited a notably long and rapid wetting from 1980 to 2005 but decreased after 2005 in fact there have been three especially dry years 2008 2014 and 2015 in the last 10 years meanwhile there was large power in the 2 1 year 2 9 year 4 1 year 5 5 year 9 5 year and 10 8 year short periods and in the 30 40 year long periods

rare earth elements in the phosphatic enriched sediment of the peru shelf abstract apatite enriched materials from the peru shelf have been analyzed for their major oxide and rare earth element ree concentrations the samples consist of 1 the fine fraction of sediment mostly clay material 2 phosphatic pellets and fish debris which are dispersed throughout the fine grained sediment 3 tabular shaped phosphatic crusts which occur within the uppermost few centimeters of sediment and 4 phosphatic nodules which occur on the seafloor the bulk ree concentrations of the concretions suggest that these elements are partitioned between the enclosed detrital material and the apatite fraction analysis of the fine grained sediment with which the samples are associated suggested that this detrital fraction in the concretions should have shale ree values the analysis of the fish debris suggested that the apatite fraction might have seawater values the seawater contribution of ree s is negligible in the nodules and crust in which the apatite occurs as a fine grained interstitial cement that is the concentration of ree s and the ree patterns are predominantly a function of the amount of enclosed fine grained sediment by contrast the ree pattern of the pelletal apatite suggests a seawater source and the absolute ree concentrations are relatively high the ree p 2 o 5 ratios of the apatite fraction of these samples thus vary from approximately zero in the case of the crust and nodules to as much as approximately 1 2 10 3 in the case of the pellets the range of this ratio suggests that rather subtle variations in the depositional environment might cause a significant variation in the ree content of this authigenic fraction of the sediment pelletal glauconite was also recovered from one sediment core its ree concentrations closely resemble those of the fish debris

spring precipitation variations over the western himalaya india since a d 1731 as deduced from tree rings 1 spring precipitation representative of regional scale features was reconstructed since a d 1731 using 15 site ring width chronologies of himalayan cedar cedrus deodara roxb ex lambert g don prepared from distantly located moisture stressed sites in the western himalayan region this is so far the strongest tree ring based precipitation reconstruction in terms of variance explained in the calibration model a d 1897 1986 from the western himalayan region the twentieth century experienced the driest and wettest years in the whole reconstructed series the 10 and 20 year means also indicate extreme precipitation periods in the twentieth century the increasing precipitation trend noticed in the reconstructed data of the late twentieth century closely matches with instrumental data

rare earth element geochemistry of hydrothermal deposits from the active tag mound 26 n mid atlantic ridge the rare earth element ree geochemistry of various phases from the active tag hydrothermal mound has been examined and related to their mineralogy and fluid chemistry the mound deposits range from black and white smoker chimneys massive anhydrite sulphide mixtures oxides and ochres all phases except black smoker chimney anhydrite demonstrate a positive eu anomaly when normalised to chondrite ree values ree substitution into sulphide and sulphate phases appears to be strongly influenced by crystallographic control for all ree other than eu precipitation of anhydrite within the tag mound is the major mechanism for removal of ree during mound circulation and 0 15 0 35 g anhydrite is inferred to precipitate from every kg of fluid venting from the white smoker chimneys oxides from the mound fall into three different categories with distinct ree patterns oxide rims on sulphides atacamite bearing oxides and silica rich fe oxides and ochres the oxide rim phases contain sulphide and seawater derived rees whereas the atacamite bearing oxides and the ochreous material exhibit no seawater signature which suggests precipitation from or alteration by a modified hydrothermal fluid

composition age and tectonic setting of amphibolites in the central bushmanland group western namaqua province southern africa abstract the western namaqua province wnp of southern africa is composed of several supracrustal assemblages and intrusive granitoid suites that were formed during the mid proterozoic 2 0 1 0 ga ago the bushmanland group bg has been the subject of intense study recently because of its considerable strategic metal potential hosting several giant stratiform base metal deposits e g gamsberg and aggeneys the bg contains amphibolites which represent metamorphosed tholeiitic basalts with mgo 9 4 and enriched in ni relative to modern basalts a feature reminiscent of archaean tholeiites post depositional mobility of elements is probably widespread and hampers recognition of parental magma composition and source region characteristics however the amphibolites have yielded a sm nd isochron age of 1649 90 ma nd t 0 48 0 89 which is interpreted as the time of extrusion of the basalt precursors and by inference a minimum sedimentation age for the underlying metalliferous bg sequence it follows that the bg sequence evolved during an intermediate period in the history of the namaqua province after major crustal stabilisation around 2 0 1 9 ga and before the last major tectonothermal event around 1 2 1 1 ga results of a parallel rb sr and u th pb study of the bg amphibolites indicate strong metamorphic resetting 1 2 1 1 ga ago thereby confirming earlier work on the wnp characteristics of the source region to the bg basalts have been inspected with morb normalised trace element abundances with the salient result being the bg basalts require derivation from a source that experienced variable geochemical modification similar to that proposed for the mantle wedge overlying modern subduction zones such a process is currently preferred over crustal contamination since the sm nd isochron for the bg amphibolites is remarkably linear but independent confirmation of the sm nd age is still required before this alternative model can be discounted to reconcile the requirement of subduction related metasomatism in the source to tholeiitic basalts erupted within what appears to be a cratonic sedimentary basin we suggest that back are continental extension could provide a satisfactory tectonic setting as such an environment is intrinsically linked to subduction

streamflow variability for the aksu river on the southern slopes of the tien shan inferred from tree ring records gauged river flow records from china generally span only a few decades which hampers the detection of long term decadal to centennial scale cycles and trends in streamflow variability new and updated tree ring chronologies help reconstructed the water year october september streamflow for the aksu river which is an important river at the edge of the taklimakan desert that drains into the tarim basin the reconstruction dates back to 1692 and has an adjusted r 2 of 0 61 1957 2006 based on frequency intensity and duration of droughts and pluvial events the lowest streamflows occurred in the 1920s since then streamflow has continuously increased and was exceptionally rapidly after the 1960s until today the start and end of the 20th century to the present were the highest streamflow periods the mid 20th century was the longest and driest period over the past 300 yr the reconstructed streamflow series has a strong positive correlation with the north atlantic oscillation index changes in mid latitude circulation patterns influencing precipitation may have indirectly resulted in streamflow variations along the aksu river over the past 300 yr the rapid increase and the exceptional streamflows of the 1960s are likely linked with global warming and mid latitude atmospheric circulation changes c 2016 university of washington published by elsevier inc all rights reserved

mineralogy bulk and rare earth element geochemistry of massive sulphide associated hydrothermal sediments of the brunswick horizon bathurst mining camp new brunswick massive sulphides are spatially and temporally associated with iron formation if and other hydrothermal sedimentary rocks in the vicinity of the brunswick no 12 brunswick no 6 and austin brook deposits bathurst mining camp sulphide carbonate oxide and silicate predominant if is present carbonate predominant if is best developed in and around the brunswick no 12 deposit whereas hematite bearing if is absent here but prominent in the austin brook brunswick no 6 area the if is composed dominantly of si co2 fe mn and ca minor constituents include mg p ti al and s statistically significant interelement correlations between eu fe mn pb zn cd au ca sr ba p co2 and s indicate that these elements were precipitated from hydrothermal fluids vented onto the seafloor positive interelement correlations between si ti al mg k zr rare earth elements ree s except eu se v y yb co ni and cr reflect the presence of detrital clastic mafic and aluminosilicate minerals and

mechanisms of subglacial groundwater recharge as derived from noble gas 14c and stable isotopic data abstract noble gas stable isotope and 14c data from samples collected along groundwater flow path within a confined paleozoic aquifer in northeastern wisconsin usa are used to deduce the effect of the laurentide ice sheet lis on the underlying groundwater and its recharge dynamics during the last glacial maximum the investigated area was near the center of the green bay lobe of the lis 14c ages that extend to 26 k a and low 18o derived temperatures during the time that the lis was present indicate that aquifer recharge continued when ice covered the area 18o values as low as 17 5 and 2h values as low as 127 7 indicate that a significant portion of aquifer recharge was derived from glacial meltwater that maintained its glacial isotopic signature during melting and subsequent recharge noble gas temperatures that remain above freezing at a constant 3 c unusually high excess air ne values and noble gas fractionation patterns indicate that recharge occurred across a very dynamic water table located within the ice sheet this englacial hydrologic system experienced recharge heads of as much as 7 8 m evidence for direct recharge of basal meltwater into the aquifer is not seen to the authors knowledge this is the first time that noble gas and isotope tracers have been used to deduce the provenance of aquifer water beneath continental ice sheets

evolution of groundwater systems at the european coastline an overview is given of the status and origin of fresh and saline groundwaters in the sedimentary aquifers at or near the present european coastline results are presented as six regional maps summarizing as far as possible the conditions likely to have existed at the end of the pleistocene after the impact of glaciation when groundwaters might be expected to have reached their maximum offshore evolution prior to the encroachment of sea water during the holocene marine transgression in the eastern baltic the groundwater evolution was different to other european regions in that freshwater heads were higher than the present day promoting recharge during much of the late pleistocene near the north sea coasts there is generally evidence of freshwater movement to depths of 100 150 m but the absence of deeper freshwater palaeowater storage may relate to the low hydraulic gradients in the north sea basin in the southeastern part of the north sea brackish palaeowater is found between tertiary marine sediments c 300 m below the island of rcmo l 0 km off the danish west coast freshwater of pleistocene and holocene ages is found in aquifers at the english channel coast in several areas to depths in excess of 300 m offshore flow in the late pleistocene took place towards the central palaeovalley and some of this groundwater may be preserved off the present coastline in the two atlantic coastal areas of france and portugal spain a contrast exists due to the proximity of the continental margin and different hydraulic gradients in portugal freshwaters are found at the coastline and probably offshore that contain evidence of recharge during the lowered sea levels in most of the southwestern atlantic coast of spain fresh recent groundwater discharges along and beyond the coastline while in the old estuary of the guadalquivir river saline holocene water still encroaches the sediments on the mediterranean coast of france and spain some salinity encroachment took place during sea level rise in most of the spanish aquifers fresh recent groundwater has substituted for palaeowater except for the low lying areas ebro delta inca sa pobla plain where brackish holocene water is still present

erratummar geol erratum to rare earth elements in phosphorite and associated sediment from the namibian and south african continental shelves 129 1995 111 128

apatite nodules as an indicator of depositional environment and ore genesis for the mesoproterozoic broken hill type gamsberg zn pb deposit namaqua province south africa nodules consisting of fluorapatite are concentrated as a discrete band in the polymetallic sulfide ore of the gamsberg deposit in central bushmanland south africa their shape zonal features and geochemistry in particular rare earth element ree abundances are similar to authigenic francolite concretions that precipitate during diagenesis in organic rich muds as a result the apatite nodules are regarded as primary the nodules have a strong lithostratigraphic control occurring at the transition of siliciclastic hosted pyrite sphalerite graphite mineralization to calc silicate hosted pyrrhotite sphalerite mineralization mineralogical and chemical evidence indicates that this transition also corresponds to a paleo redox boundary that separates sediments deposited under oxygen deficient conditions from those that developed in a more oxygenated environment the apatite nodules can morphologically and chemically clearly be distinguished from coarse apatite grains that occur in oxide facies iron formations stratigraphically above the ore horizon however similar ree profiles and in particular positive eu anomalies in both types of apatite are indicative of a close genetic relationship between the two units and favor a common hydrothermal origin of the p the contrasting morphologies and chemical signatures of the two occurrences can rather be attributed to differences in behavior of the phosphates during precipitation within the contrasting host sediments chemical versus fine grained clastic taking modern phosphorites as an analogue these results are used to postulate a genetic model for the deposition of the sulfide ore and associated iron formations the model envisages differentiation of the depositional basin into oxygen deficient basin facies hosting the sulfide ore and oxygenated shelf facies which are composed of manganiferous iron formations the intimate association of sedimentary apatite with base metal sulfides indicates that basin conditions were conducive to the precipitation of both phases this relationship might act as a potential exploration guide in similar basins elsewhere

glacier meltwater flow paths and storage in a geomorphologically complex glacial foreland the case of the tapado glacier dry andes of chile 30 s summary the tapado catchment is located in the upper elqui river basin 4000 5550 m in northern chile it comprises the tapado glacial complex which is an assemblage of the tapado glacier and the glacial foreland debris covered glacier rock glacier and moraines although the hydrological functioning of this catchment is poorly known it is assumed to actively supply water to the lower semi arid areas of the elqui river basin to improve our knowledge of the interactions and water transfers between the cryospheric compartment glacier debris covered glacier and rock glacier and the hydrological compartment aquifers streams the results of monitoring of meteorological conditions as well as discharge conductivity and temperature of streams and springs located in the tapado catchment were analyzed the hydrological results are compared to results inferred from a ground penetrating radar gpr survey of the underground structure of the glacial foreland water production from the tapado glacier was shown to be highly correlated with daily and monthly weather conditions particularly solar radiation and temperature the resulting daily and monthly streamflow cycles were buffered by the glacial foreland where underground transfers took place through complex flow paths however the development of a thermokarst drainage network in a portion of the glacial foreland enabled rapid concentrated water transfers that reduced the buffer effect the glacial foreland was shown to act as a reservoir storing water during high melt periods and supplying water to downstream compartments during low melt periods gpr observations revealed the heterogeneity of the internal structure of the glacial foreland which is composed of a mixture of ice and rock debris mixture with variable spatial ice content including massive ice lenses this heterogeneity may explain the abovementioned hydrological behaviors finally calculation of a partial hydrological budget confirmed the importance of the tapado catchment in supplying water to lower areas of the elqui river basin water production from and transfer through cryospheric compartments and its subsequent interactions with hydrological compartments are key processes driving the summer water supply from the tapado catchment

metamorphic alteration mineral paragenesis and geochemical re equilibration of early archean quartz amphibole pyroxene gneiss from akilia southwest greenland quartz amphibole pyroxene gneiss from the island of akilia southwest greenland has been claimed to contain the earliest traces of life on earth in the form of biogenic carbonaceous matter encapsulated as inclusions in apatite crystals various lines of evidence including petrography geochronology field relations and geochemistry have however been presented that challenge this interpretation textural relationships and geochemical signatures in this controversial gneiss presented here manifest a complex spatially variable metamorphic history that includes granulite and amphibolite facies overprints and metasomatism a peak metamorphic granulite facies quartz orthopyroxene clinopyroxene amphibole magnetite assemblage is preserved in only a few centimeter scale layers within the 5 m thick quartz amphibole pyroxene gneiss unit calcite veinlets that appear to postdate the peak metamorphism occur in pyroxene the quartz amphibole pyroxene gneiss unit has subsequently experienced isochemical except hydration amphibolite facies alteration during which pyroxenes were retrogressed to amphiboles and magnetite and calcite was consumed parts of the quartz amphibole pyroxene gneiss that contain texturally late hornblende have experienced metasomatic alteration by al carrying fluids these fluids controlled the alteration of pyroxenes and amphiboles to hornblende and modified the trace element composition by remobilizing lree and eu apatite has variable ree composition and 87sr 86sr in the quartz amphibole pyroxene gneiss but on the local scale cm is in equilibrium with co existing silicates effective recrystallization of apatite crystals as well as co existing silicates during several stages of the metamorphic history makes the intact preservation of diagenetic apatite with encapsulated primary carbonaceous matter implausible hence it is highly unlikely that akilia apatite could serve as repository of the earliest traces of life on earth

mid to late holocene climate evolution of the lake telmen basin north central mongolia based on palynological data abstract palynological and sedimentological data from lake telmen in north central mongolia permit qualitative reconstruction of relative changes in moisture balance throughout the mid to late holocene the climate of the atlantic period 7500 4500 yr ago was relatively arid indicating that lake telmen lay beyond the region of enhanced precipitation delivered by the expanded asian monsoon maximum humidity is recorded between 4500 and 1600 cal yr b p during the subboreal 4500 2500 yr ago and early subatlantic 2500 yr present periods additional humid intervals during the medieval warm epoch 1000 1300 a d or 950 650 ago and the little ice age 1500 1900 a d or 450 50 yr b p demonstrate the lack of long term correlation between temperature and moisture availability in this region a brief aridification centered around 1410 cal yr b p encompasses a decade of cold temperatures and summer frost between a d 536 and 545 1414 1405 yr b p inferred from records of mongolian tree ring widths these data suggest that steppe vegetation of the lake telmen region is sensitive to centennial and decadal scale climatic perturbations

a strategy to improve the contribution of coral data to high resolution paleoclimatology abstract various geochemical tracers measured in massive coral skeletons have the potential to compliment other sources of high resolution proxy climate information e g tree rings ice cores by providing paleoclimatic data from shallow water tropical ocean regions twenty previously published coral records 19 18o and one sr ca series between 54 and 346 years in length were examined for their local and larger scale relationships el nino southern oscillation with climate series were examined in a consistent manner over the same time periods and relationships were tested for stability through time the results demonstrate a spectrum of climatic interpretation ranging from 1 no significant relationship of the coral record with either local or larger scale climate variables 2 significant relationship of the coral record with climate but the relationship is not stable through time and 3 the coral record shows a significant and temporally stable relationship with climate which explains a significant and useful proportion of climate variance it is concluded that reliance to date on analyzing only one long coral core from a site has prevented identification of coral records or parts of coral records where non climatic factors are dominating the geochemical signal various factors may cause these non climatic signals to dominate more process studies into how corals of particular species with various growth rates and from various environmental settings incorporate geochemical tracers into their skeleton are required to understand exactly what is being measured in addition it is recommended that some level of replication ideally three separate corals of geochemical tracers will ensure accurate dating of the record identification of periods when non climatic factors dominate and thus enhance the reliability of the paleoclimatic record such an approach will allow the rich archive of environmental information contained in massive coral skeletons to make a significant contribution to high resolution paleoclimatology and improve our understanding of the nature and causes of past climate variability

tree ring based drought reconstruction for the central tien shan area in northwest china 1 a robust ring width chronology developed from two sites of picea schrenkiana in the central tien shan area of northwest china was employed to study regional drought variability our analyses demonstrate both temperature and precipitation have significant effects on tree growth thus both should be considered for climate reconstruction regional drought history 1675 2002 a d was therefore reconstructed by calibrating with the palmer drought severity index pdsi our reconstruction not only captured well those extreme drought events recorded in local historical archives but also revealed the long term pattern of drought variability especially the trend of increasing moisture during the 20th century multi taper method spectral analysis indicates the existence of some low and high frequency cycles 146 171 11 5 10 6 9 7 6 1 3 9 3 4 3 2 2 4 and 2 1 yr overall our study indicates the feasibility of combining tree rings and the pdsi to reconstruct large scale drought patterns over this area

rare earth elements in phosphorite and associated sediment from the namibian and south african continental shelves rare earth elements ree and major elements have been determined in twenty nine phosphorite and associated sediment samples from the southwestern coast of africa including thirteen samples of unconsolidated sediment collected during recent cruises to phosphate rich areas on the namibian shelf the concentrations of ree in various phosphorite types from southwestern africa differ by more than two orders of magnitude the samples mostly exhibit ree patterns which are similar to that of shale having no ce anomaly the ce content appears to have been controlled by the palaeoredox conditions of the localised environment of deposition or diagenesis and not to have been influenced by marine upwelling or by the general palaeoredox conditions of the water column the environments in which ree were incorporated into the francolite appear to have been anoxic or sub oxic in the case of both namibian unconsolidated authigenic phosphorites and the predominantly diagenetic phosphorites off the south african coast the ultimate ree source in both cases appears to have been mainly eolic continental detritus pelletal phosphorites are significantly enriched in ree relative to non pelletal varieties if sequestration of ree dissolved in the water column contributed to the high concentrations of ree in pelletal phosphorites then the main carrier phase appears to have been inorganic detritus or biogenic silica equilibrated with oxygen depleted bottom waters but not fish debris the contention that onland phosphorites are enriched in ree relative to their offshore counterparts is however refuted in the case of southwestern africa and the effects of groundwater ree enrichment are not obvious in the majority of onland phosphorites analysed in this study

stalagmite based high resolution precipitation variability for past four centuries in the indian central himalaya chulerasim cave re visited and data re interpretation abstract although the variations in 18 o and 13 c and the u th dating in the speleothems are considered as key proxies improved dating with better quality resolution as well as composition of stalagmites and growth rate along with the cave monitoring are equally important for understanding the high resolution precipitation variability in the past with a total of six dates on a 11 5 cm long stalagmite we re interpret the decadal to century scale climatic changes with multi year droughts from the indian central himalaya between ca 1622 and 1950 ad the sample is composed of aragonite both compact sub layers and porous sub layers although the age model of this young speleothem may be within age uncertainty owing to the high 230 th 23 2 th isotope ratios yet the distinction of this study lies in recording various historical drought events which are otherwise never reported from the himalayan foothills additionally the sample consists of reasonable amount of u 2 ppm thus the age correction requirement may be minimum the higher growth rate and comparatively lower values of 18 o and 13 c are observed during the little ice age lia until ca 1820 ad indicating its being wet in the himalayan foothills in contrast to the peninsular india and other regions which are solely influenced by the indian summer monsoon ism this is mainly because the monsoon trough moves from the plains to the himalayan foothills during break monsoon conditions and provides more orographic precipitation in form of the westerlies in the south facing himalayan slopes the post lia period from ca 1820 ad onwards is interpreted as comparatively drier than the lia

glacial hydrology and erosion patterns a mechanism for carving glacial valleys article i nfo article history most glacial erosion models assume that erosion rates are proportional to ice sliding velocity while recent studies have shown that water plays a major role in modulating sliding velocities the impact it might have on erosion rates is still unclear here we incorporate subglacial hydrology into a glacial erosion model that is based on a sliding rule our results explicitly highlight that adding subglacial hydrology has profound impacts on the temporal and spatial patterns of glacial erosion first it suggests that erosion might mainly occur during melting seasons when subglacial water pressure is large and effective pressure is low i e before the channels fully develop and reduce the water pressure at the ice bedrock interface which promotes sliding and erosion second the distribution of erosion is bimodal with a peak at the equilibrium line altitude and as we demonstrate enhanced erosion at much lower altitudes within the ablation area where water due to melting abounds this has important implications because it explains why glacial erosion can simultaneously

europium redox equilibria in aqueous solution thermochemical data and recent advances in theoretical aqueous solution chemistry enable prediction of the relative stabilities of aqueous eu2 and eu3 over a wide range of temperatures and pressures at low temperatures near earth surface conditions the aqueous geochemistry of europium should be dominated by the trivalent state except possibly in the most reducing alkaline pore waters of anoxic marine sediments however at temperatures greater than about 250 c and elevated pressures divalent europium should predominate even with significant amounts of complexing trivalent europium is not stable at elevated temperatures and pressures consequently under most hydrothermal and metamorphic conditions europium in aqueous solution should be divalent at intermediate temperatures around 100 c significant activities of both eu2 and eu3 and related complexes can occur in aqueous solutions depending on the oxidation state and the ph of the solutions and the activities of potential ligands such as sulfate carbonate and chloride the predicted stability of divalent europium in aqueous solution at elevated temperatures is consistent with the large positive europium anomalies in rare earth element patterns of high temperature barites of hydrothermal and metamorphic origin reported by guichard et al 5 and with the observed depletion of europium as a result of high temperature sericitization of feldspar bearing assemblages discovered by alderton et al 1 it is suggested that significant fractionation of europium relative to the other rare earth elements may take place during high temperature hydrothermal alteration processes such as in the mid oceanic ridge systems because of the expected stability of divalent europium during these processes

revision of fontes garnier s model for the initial 14c content of dissolved inorganic carbon used in groundwater dating abstract the widely applied model for groundwater dating using 14c proposed by fontes and garnier fg or 2 using different fractionation factors if the exchange process is dominated by soil co2 gas as opposed to solid carbonate mineral typically calcite an analysis of the fg however 14c0 will be slightly underestimated finally in carbonate systems undergoing complex geochemical reactions such as oxidation of organic carbon radiocarbon ages are best estimated by inverse geochemical modeling techniques

phosphorites of rocinha mine patos de minas minas gerais brazil genesis and evolution of a middle proterozoic deposit tectonized by the brasiliano orogeny in central brazil the states of minas gerais and goias the brasiliano orogeny asymp 600 ma delineates the sao francisco craton and to the west the brasilia fold belt rocks of the fold belt are thrust to the east and display increasing deformation and metamorphism westward almost all the phosphate deposits are found in the brasilia fold belt either along its boundary with the craton or in external structural units showing polycyclic deformation and greenschist metamorphism they occur in the metasedimentary rocks of the middle proterozoic paranoa group and in the upper proterozoic sao francisco group and its equivalents middle proterozoic phosphorites are economically the more important most are spatially and temporally associated with a stromatolite reef barrier however the rocinha patos de minas deposit the only presently mined is located south of the reef barrier it has developed on a shallow to deep ramp between a wide internal basin with reduced oxygen conditions and limited detritus and a more oxygenated marine environment to the west in the rocinha mine phosphate forms grains angular fragments lenses or centimeterthick beds in schists and carbonate or glauconitic schists the p 2 o 5 content of phosphatic rocks ranges between 10 and 15 percent annual production is around 200 000 tons of ore containing 24 percent p 2 o 5 the mine area comprises four tectonic slices made up of schists quartzoschists and phosphatic schists separated by subhorizontal shear planes these are defined by tectonic breccias in which secondary apatite has recrystallized the mine is exposed in a 50 to 75 m phosphatic sequence which is repeated in a lower slice about 100 m below mine level the phosphatic ore is a homogeneous crypto to microcrystalline apatite in fairly continuous centimeter thick beds which were stretched fragmented and boudinaged during brasiliano isoclinal folding and subsequent subhorizontal shearing x ray diffraction ir spectrometry and chemical analysis indicate that the metasedimentary phosphate is a weakly carbonated fiuorapatite with low f and co 2 contents the influence of the brasiliano orogenesis is marked by partial substitution of f by oh secondary prismatic apatite kaolinite coatings and wavellite sheaflike structures are products of weathering and are found in mine sections and bore holes to a depth of 10 to 15 m secondary apatites are enriched in co 2 compared to primary metasedimentary apatites

twentieth century summer temperature variability in the southern altai mountains a carbon and oxygen isotope study of tree rings the altai mountains southern siberia represent an area of significant scientific interest and exceptional palaeoecological potential to assess the influence of climate on the stable isotopic composition of tree ring cellulose and the potential of this record as a palaeoclimate proxy replicated stable oxygen and carbon isotope time series were developed for the twentieth century from four siberian pine pinus sibirica du tour trees growing near the settlement of aktash russian altai mountains southern siberia bootstrapped calibrations for the local instrumental period ad 1954 2000 reveal strong correlations between summer july august growing season temperatures and tree ring oxygen r2 0 55 and carbon r2 0 30 isotopes covariance observed between both carbon and oxygen isotope data suggest a common stomatal control the resulting empirical model was used to reconstruct regional summer temperatures for the twentieth century no divergence is observed between the non detrended tree ring isot

monsoon variability and major climatic events between 25 and 0 05 ka bp using sedimentary parameters in the gangotri glacier region garhwal himalaya india abstract gangotri glacier has attracted international attention for its rapid rate of retreat it is one of the best studied himalayan glaciers however there are no unanimous views about the history of climate change for the gangotri glacier we prepared the lithologs textural logs by making two trenches in the kame terraces and analysed it in detail for sediment grain parameters and 14c ams dates to infer the depositional sedimentary environments monsoon variability and major climatic events in the gangotri glacier region the sedimentary parameters and geomorphic analysis revealed that the sediments of the kame terraces are consolidated to semi consolidated stratified very coarse to fine grained layers of sand silt and clay with few gravels and sedimentary structures the sediment size indicating energy of the depositional environment varies from medium to fine sand 1 02 2 26 the standard deviation is poorly sorted 0 89 1 46 which describes that the energy of the depositional environment is continuously fluctuating the positive skewness 0 32 0 98 indicates the excess of finer sediments and dominance of low energy whereas very leptokurtic kurtosis 2 28 4 47 describes the fluctuating energy conditions the present study explains the glacial stages and weak indian summer monsoon ism around 19 5 14 5 13 1 10 1 8 6 7 5 2 2 0 54 0 08 ka bp and warm and intense ism during 23 9 22 7 19 4 1 15 0 05 ka bp the higher percentage of clay in both the trenches around 0 65 0 2 ka bp 1300 1750 ad and higher percentage of silt and low clay content around 1 15 0 55 ka bp 800 1400 ad validates the little ice age lia and medieval warm period mwp respectively

the interglacial glacial cycle and geochemical evolution of canadian and fennoscandian shield groundwaters abstract results from cryogenic column experiments are compared with the geochemical data collected in the canadian and fennoscandian shields over the past 25 years to investigate the relative influence of the glacial interglacial cycle specifically the impact of continental glaciers permafrost and methane hydrate on the evolution of groundwater from crystalline shield environments several different geochemical indicators of freezing processes either glacial or permafrost related were utilized comparisons of na cl and br cl ratios 18 o and 2 h values and 18 o values and cl concentration during freezing fluids with different dominant cations follow distinctly different linear trends when na cl and br cl ratios are compared significantly none of the freezing trends follows the trend hypothesized by herut et al 1990 for the evolution of seawater chemistry during freezing intrusion of glacial meltwater and in situ freezing i e permafrost formation result in a similar end member when comparing 18 o values and cl concentration the geochemical influence of a freezing process on fresh brackish and some saline fluids was identified at some but not all canadian shield sites regardless of site location with respect to modern day permafrost appreciably physical and geochemical data do not support the formation of brines through any freezing process in the canadian and fennoscandian shields as hypothesized by starinsky and katz 2003 rather on all diagnostic freezing plots brines are an end member indicating a different evolutionary pathway significant depletions in 18 o with respect to modern precipitation an indication of either glacial meltwater or a freezing process were identified at depths of up to 1 km at some sites in the canadian shield and to shallower depths in the fennoscandian shield the potential of this fluid to reach such depths could be attributable to artificial gradients and mixing glacial recharge permafrost or paleo permafrost formation or methane hydrate or paleo methane hydrate formation at most locations it was not possible to distinguish between the different scenarios using the current geochemical database

rare earth element study of exhalites within the willyama supergroup broken hill block australia a wide variety of unusual rock types exhalites are commonly associated with or host to exhalative mineralisation within the willyama supergroup chondrite normalised ree patterns of feldspar gahnite calcite magnetite and garnet rich lithologies in the vicinity of stratiform broken hill type pb zn ag mineralisation are lree and eu enriched similar to the ree patterns of pure metalliferous sediments and hydrothermal fluids of the east pacific rise and the red sea in contrast tourmaline garnet amphibole feldspar and gahnite rich exhalites in strike extension of broken hill type orebodies possess lree enrichments and negative eu anomalies and also hree enrichments and negative ce anomalies these ree patterns are the result of decreasing temperatures of the hydrothermal fluids changing oxidation reduction conditions and increasing influence of basic volcanism with increasing distance from the sulphide mineralisation

rare earth geochemistry of phosphorites abstract the abundance of rare earth elements ree s in francolite increases with increasing age as a result of post depositional enrichment abundances are higher in pelletal samples than in non pelletal ones because the higher surface mass ratio of pelletal francolite promotes enrichment during diagenesis onshore francolite has higher ree abundances than that found offshore distribution patterns in francolite may be similar to those reported for open ocean water or shale depending upon the dominant source of the ree s different patterns result from weathering and deep burial diagenetic modification of the original patterns and abundances negative ce anomalies occur in francolites containing structural sulphur that is isotopically indistinguishable from seawater of the same age zero or positive anomalies occur in francolites which contain sulphur that is isotopically lighter than seawater

using stable isotopes to characterize the conditions of groundwater formation on the eastern slope of the baltic shield nw russia abstract repeated continental glaciations and marine transgressions had a strong influence on the geochemical evolution of groundwater systems of the eastern slope of the baltic shield arkhangelsk region russia the spectrum from modern fresh waters to very old brines is distributed from the surface to a depth of 1 km in quaternary and vendian ediacaran sediments the purpose of this study was to i assess the isotopic composition of various types of groundwater ii assess the degree of participation of glacial melt and meteoric waters in the processes of dilution of seawater and brines according to isotope geochemical data and iii employ the use of stable isotopes to clarify previously performed groundwater dating it has been established that the salty water in the upper part of the vendian aquifer near the modern sea coast has maximum enrichment by heavy isotopes 18o 7 7 and 2h 98 9 on average it is a mixture of 19 51 glacial meltwater and 49 81 seawater the age of the marine component is 115 130 ka and the age of the glacial water is similar to that of the middle pleistocene the relict brackish water in the middle part of the vendian aquifer has the most depleted isotope composition 18o 14 1 and 2h 106 7 on average it is a mixture of 3 brine 8 19 glacial and 78 89 interglacial water and was formed in the range of 35 3 22 3 ka late pleistocene the maximum brine content 10 17 is characteristic of salt water in the lower part of the vendian aquifer the isotope composition of the fresh water is close to the weighted annual composition of modern precipitations 18o 13 2 and 2h 98 9 fresh water is a mixture of about 2 seawater up to 16 glacial water and 84 100 holocene water the age of this water is in the range from the present day to 11 8 1 6 ka the maximum depth of penetration of melt glacial waters of the middle pleistocene is assumed to be 600 m

trace and rare earth element geochemistry of phosphate nodules from the lower cambrian black shale sequence in the mufu mountain of nanjing jiangsu province china abstract phosphate nodules are abundant in the lowermost section of the lower cambrian black shale sequence along a ne trend belt in the yangtze platform south china in this study we examined the neoproterozoic cambrian mufu mountain section near nanjing of jiangsu province and conducted a detailed trace and rare earth element ree study on the phosphate nodules we employed a step leaching acid dissolution protocol of 1 m hac and 1 m hcl respectively to separate carbonate from phosphate mineral contributions in the nodules both the hac leached and hcl leached fractions of the phosphate nodules show similar symmetrical variations in trace and ree concentrations and ratios the total rees and a number of redox sensitive trace metals such as v cr mo ni abundances show a systematic increase from the core to rim whereas the u and mn abundances decrease from the core to rim in most of the nodules similar trends are also observed for the rb sr u th co ni and v ni ratios but these trends in the hac leached fractions are less pronounced than the hcl leached fractions all of the hcl leached fractions for the nodule cores show seawater like shale normalized ree patterns but the rims of the nodules display slightly mree enriched and hree depleted patterns we suggest that the phosphate nodules may have formed in a basinal setting beneath a stratified water column during early cambrian and the compositional variations of rees and redox sensitive trace elements from the core to rim may record a changing redox condition and fluid mixing during different stages of nodule growth the cores of the nodules preserve more pronounced negative ce anomalies and progressively hree enriched patterns which may retain primary early cambrian seawater chemistry whereas the nodule rims record chemistry consistent with changed redox conditions and or influences from pore fluids such as generated from degradation of organic matter

a multicentury reconstruction of may precipitation for the mid atlantic region usingjuniperus virginianatree rings abstractthis paper presents a multicentury reconstruction of may precipitation 1200 1997 for the mid atlantic region of the united states the reconstruction is based on the first principal component pc1 of two millennial length juniperus virginiana l eastern red cedar tree ring chronologies collected from rocky limestone sites in the ridge and valley province of west virginia a split calibration linear regression model accounted for 27 of the adjusted variance in the instrumental record and was stable through time the model was verified by the reduction of error re 0 21 and coefficient of efficiency ce 0 20 statistics multidecadal changes in precipitation were common throughout the reconstruction and wetter than median conditions and drier than median conditions occurred during the medieval climate anomaly 1200 1300 and the little ice age 1550 1650 respectively the full reconstruction contained evidence of interannual and decadal variability however the twentieth century reco

tree ring precipitation reconstruction in the chifeng weichang region china and east asian summer monsoon variation since a d 1777 1 the total precipitation of previous august to current july was reconstructed on the basis of the pinus tabulaeformis ring widths from three sites in chifeng and weichang regions china for the past 236 years the explained variance of reconstruction is 47 4 the intervals with below average precipitation 1768 2003 comprise 1779 1806 1853 1883 1926 1972 and 1980 1989 the intervals with above average precipitation consist of 1807 1852 1884 1925 1973 1979 and 1990 1999 precipitation in the study area is dependent on the east asian summer monsoon strength the reconstructed series is significantly correlated with the average dryness wetness index series of datong and beijing as well as with previous results from baiyinaobao helan mountains and even the state of mongolia a significant negative correlation r 0 63 p 0 0001 is also found between the reconstruction and our previously reconstructed temperatures of weichang for the period 1884 2002 our result suggests that the variations of the east asian summer monsoon on a decadal scale are coincident with the other regions within the environmentally sensitive zone of northern china as well as mongolia for the past 236 years and our reconstruction is representative of regional climate patterns

the recharge of glacial meltwater and its influence on the geochemical evolution of groundwater in the ordovician cambrian aquifer system northern part of the baltic artesian basin abstract the geochemical evolution of groundwater in the ordovician cambrian aquifer system in the northern part of the baltic artesian basin bab illustrates how continental glaciations have influenced groundwater systems in proglacial areas the aquifer system contains water that has originated from various end members recent meteoric water glacial meltwater and relict na cl brine the saline formation water that occupied the aquifer system prior to the glacial meltwater intrusion has been diluted by meltwaters of advancing retreating ice sheets the diversity in the origin of groundwater in the aquifer system is illustrated by a wide variety in 18 o values that range from 11 to 22 5 these values are mostly depleted with respect to values found in modern precipitation in the area the chemical and isotopic composition of groundwater has been influenced by mixing between waters originating from different end members in addition the freshening of a previously saline water aquifer due to glacial meltwater intrusion has initiated various types of water rock interaction e g ion exchange carbonate mineral dissolution

hydrometeorological reconstructions for northeastern mongolia derived from tree rings 1651 1995 reconstructions of annual prior august current july precipitation and streamflow 345 yr in length 1651 1995 are presented for northeastern mongolia based on tree ring width data these precipitation and streamflow reconstructions account for 54 and 48 of the respective variance in instrumental data over the past 50 years variations in instrumental precipitation and streamflow are within the range of those reconstructed over the length of tree ring records however there appear to be more frequent extended wet periods during the twentieth century multitaper spectral analysis revealed statistically significant peaks at 10 8 and 12 8 yr for the precipitation reconstruction and at 12 8 and 20 3 23 8 yr for the streamflow reconstruction similarly singular spectrum analysis identified spectral modes of variation at 12 and 21 yr for both series these spectra resemble those found for tree ring based precipitation reconstructions in central china as well as the western united states and may reflect solar influences on the climate of mongolia

pleistocene hydrology of north america the role of ice sheets in reorganizing groundwater flow systems 1 while the geomorphic consequences of pleistocene megafloods have been known for some time it has been only in the past 2 decades that hydrogeologists and glaciologists alike have begun to appreciate the important impact that ice sheet aquifer interactions have had in controlling subsurface flow patterns recharge rates and the distribution of fresh water in confined aquifer systems across north america in this paper we document the numerous lines of geochemical isotopic and geomechanical evidence of ice sheet hydrogeology across north america we also review the mechanical thermal and hydrologic processes that control subsurface fluid migration beneath ice sheets finite element models of subsurface fluid flow permafrost formation and ice sheet loading are presented to investigate the coupled nature of transport processes during glaciation deglaciation these indicate that recharge rates as high as 10 times modern values occurred as the laurentide ice sheet overran the margins of sedimentary basins the effects of ice sheet loading and permafrost formation result in complex transient flow patterns within aquifers and confining units alike using geochemical and environmental isotopic data we estimate that the volume of glacial meltwater emplaced at the margins of sedimentary basins overrun by the laurentide ice sheet totals about 3 7 104 km3 which is about 0 2 of the volume of the laurentide ice sheet subglacial infiltration estimates based on continental scale hydrologic models are even higher 5 10 of meltwater generated these studies in sum call into question the widely held notion that groundwater flow patterns within confined aquifer systems are controlled primarily by the water table configuration during the pleistocene rather groundwater flow patterns were likely much more complex and transient in nature than has previously been thought because pleistocene recharge rates are believed to be highly variable these studies have profound implications for water resource managers charged with determining sustainable pumping rates from confined aquifers that host ice sheet meltwater

non hydrothermal origin of apatite in sedex mineralization and host rocks of the howard s pass district yukon canada the howard s pass district hpd comprises 14 zn pb sedimentary exhalative sedex deposits and is located within the selwyn basin yukon canada although the hpd is renowned for its large accumulation of base metal sulfides in places the late ordovician to early silurian host rocks also contain abundant carbonate bearing fluorapatite cbfa this mineral is present stratigraphically be low within and above the sedex deposits and occurs as fine grained layers that are interbedded with cherty carbonaceous mudstone electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometric analysis reveal that mineral compositions and rare earth element yttrium ree y systematics respectively are remarkably similar throughout the stratigraphic succession north american shale composite nasc normalized la sm and la yb ratios indicate that the original ree compositions in cbfa have undergone only minor compositional modification subsequent to deposition uniformly negative ce anomalies indicate that the mineral formed in analogous manner to modern and ancient sedimentary phosphorites under suboxic bottom water conditions europium anomalies are mostly absent indicating that reduced slightly acidic high temperature hydrothermal fluids were not a major source of ree y to cbfa the chemical homogeneity of the mineral irrespective of its stratigraphic position indicates that a common process was responsible for its deposition within the sedimentary rocks of the hpd on the basis of the similarity of the ree patterns to modern and ancient phosphorites and the absence of positive eu anomalies we conclude that the cbfa is of hydrogenous origin and not hydrothermal as suggested by previous workers as such phosphorite formation in the hpd is casually related to sedex zn pb deposit formation

precipitation reconstruction from hailar pine pinus sylvestris var mongolica tree rings in the hailar region inner mongolia china back to 1865 ad article precipitation is the major limiting factor for the radial growth of hailar pine pinus sylvestris var mongolica i n the hailar northeast china herein the amount of precipitation from the previous july to current june was chosen for reconstruction from 1865 to 2003 ad this reconstruction accounts for 51 of the variance in the instrumental precipitation data during the 1952 2003 period the reconstruction reveals the precipitation fluctuation history over the last 139 years some severe drought events lasting for more than 3 years are displayed in theseries such as 1905 1909 1926 1929 asevere drought event in central northern china with tremendous losses of human lives and 1968 1970 extreme wet events are 1867 1870 1932 1934 1939 1941 and 1955 1957 on the decadal scale there are two dry periods with precipitation lower than the mean of 1865 2003 1888 1929 and 1963 1975 and two wet intervals more than the mean 1930 1962 and 1976 2003 drought events or dry intervals correspond to weak and wet events to strong east asian summer monsoon easm the reconstructed precipitation can be well compared with the baiyinaobao ortindag sand land in eastern inner mongolia and northeastern mongolia rainfall series derived from tree rings the four curves show similar variation related to weak strong easm a power spectrum analysis shows that there are 7 67 and 7 08 year quasi periodicities which may be associated with enso activity

early diagenesis of organic matter in peru continental margin sediments phosphorite precipitation abstract pore water chemistry total dissolved co 2 nh 4 no 3 no 2 po 4 si oh 4 ca mg fe mn so 4 h 2 s and f and titration alkalinity solid phase chemistry c org p org c tot n tot f si opal and s ii and sediment characteristics porosity dry bulk density and formation factors were determined on a centimeter scale spacing in the upper 20 40 cm of sediments under intense upwelling areas on the peru continental shelf these data demonstrate that carbonate fluorapatite cfa is precipitating from pore waters in the upper few centimeters of a gelatinous mud with high organic carbon content up to 20 c org very high porosity 0 96 ml cm 3 and very low dry bulk density 3 dissolved phosphate concentrations at the sediment water interface range from 20 to 100 m orders of magnitude higher than bottom water concentrations and much higher than predicted from regeneration of organic matter the mechanism of this interfacial phosphate release is unclear but is apparently uncoupled from carbon and nitrogen metabolism and thus may be linked either to dissolution of fish debris or to the presence of a microbial mat in surficial sediments fluoride is incorporated into cfa by diffusion from the overlying seawater and carbonate ions are provided from pore water alkalinity magnesium concentrations in this reaction zone are not significantly different from those of seawater suggesting that magnesium depletion is not a necessary prerequisite for cfa precipitation the environment of precipitation is interface linked rather than driven by organic diagenesis of phosphorus deeper in the sediment most of the cores display a wide range of diagenetic characteristics below the immediate interfacial region but almost all show the precipitation signature near the interface this interface linked early diagenetic porewater environment for the precipitation of cfa explains many of the geochemical characteristics of phosphorites and provides a testable model to compare the modern phosphogenic analog with ancient phosphorite deposits two of the cores display very high solid phase phosphorus and fluoride contents reflecting the presence of apparently modern pelletal apatites