isotopic constraints on the origin of groundwater in the ordos basin of northern china despite its extreme aridity the ordos basin in northern china is rich in groundwater many artesian wells or springs with large fluxes are utilized for drinking irrigation and industrial production in a search for the origin of the groundwater a detailed investigation of the stable isotopes of oxygen and hydrogen in the local precipitation the river water the springs the well water as well as the soil water extracted from six soil profiles in the ordos basin was carried out the data show that d 18o and tds values of the river water are similar to those of groundwater while the tds values of the soil water are about ten times greater than those of groundwater furthermore the mean isotopic compositions of the local precipitation are significantly higher than those of river water and groundwater based on the chloride mass balance method the estimated recharge rates range from 5 2 to 17 2 mm year with a mean value of 10 5 mm year the results show that the main source of recharge of the groundwater in the ordos basin is not the local precipitation but must come from a region where the precipitation is characterized by much lower d and 18o values in addition the groundwater in the ordos basin contains a component of mantle derived 3he and crust derived 4he suggesting that the groundwater may partly derive from flows through basement faults beneath the ordos basin

chemistry of rainwater in the massif central france a strontium isotope and major element study atmospheric aerosols sea salt crustal dust and biogenic aerosols are the primary source of dissolved species in rainwater as well as one of the sources of dissolved species in river water chemical weathering studies require quantification of this atmospheric input the crustal component of atmospheric input can have various origins both distant and local the proportions of the various inputs marine distant or local are determined in this study strontium isotope ratios and ca na k mg al cl so4 no3 and sr concentrations were measured in rainwater samples collected in the massif central france over a period of one year each sample collected automatically represents a monthly series of rain events chemical composition of the rainwater samples varied considerably and the 87sr 86sr ratios ranged between 0 709198 and 0 713143 using na as an indicator of marine origin and al for the crustal input in rain samples the proportion of marine and crustal elements was estimated from elemental ratios a marine origin of 4 to 100 of cl of 0 6 to 20 of the so4 of 1 to 10 of ca 1 to 40 of k 4 to 100 of mg and 1 to 44 of sr was determined strontium isotopes were used to characterize the crustal sources the 87sr 86sr ratios of the crustal sources varied considerably from 0 7092 to 0 71625 and indicate the occurrence of multiple sources for the crustal component in the analysed rainwaters

oscillatory marine response to the cretaceous tertiary impact magnetic susceptibility records of deep sea drilling project sites indicate that the cretaceous tertiary impact amplified or induced strong 100 k y oscillations in south atlantic sediment properties the timing amplitude and persistence of these oscillations suggest that the impact enhanced the sensitivity of the oceans to orbital forcing for almost 1 m y

middle and late jurassic radiolarian palaeoecology versus carbon isotope stratigraphy abstract jurassic radiolarians are sensitive to palaeoclimatic palaeoceanographic changes recorded by the stable carbon isotope curve carbon isotopic variations have been linked to changes in ocean structure productivity and concentrations of greenhouse gases in the atmosphere in the middle upper jurassic terminilletto section of the umbria marche sabina apennines central italy well preserved radiolarians are present in a sequence of cherty limestones interbedded with platform derived carbonates the 13 c curve in the aalenian kimmeridgian interval indicates three main positive 13 c events in the lower bajocian late bathonian lower callovian and middle oxfordian the positive 13 c shifts are correlated to increases in visible chert in the outcrop and may represent periods of increased biological productivity of surface sea water spumellaria nassellaria ratios and the fluctuations of relative abundance of selected genera tend to correlate with 13 c and chert abundance values and seem to be related to episodes of high nutrient mobilisation from the base of the bajocian the radiolarian associations show a slight tendency towards diversification coincident with increasing 13 c values in the upper part of the middle bajocian last appearances prevail over first appearances associated with the peak of the 13 c event this may indicate maximum eutrophic conditions coincident with the late bathonian early callovian positive 13 c shift the radiolarian associations record a different trend with respect to the bajocian event when the 13 c values are increasing to a maximum radiolarian associations tend to be reduced in species diversity followed by a small diversification trend when the 13 c values are decreasing we speculate that during the callovian a more stressful palaeoenvironment due to high level of eutrophication is indicated by the combination of high productivity of biogenic silica and low carbonate input although varying preservational conditions may have influenced the observed trends in the radiolarian associations the good correlation between changes of sedimentation patterns radiolarian assemblages and 13 c positive anomalies open interesting avenues for further investigations concerning the palaeoecology of mesozoic radiolarians

sr and 87sr 86sr in rivers draining the deccan traps india implications to weathering sr fluxes and the marine 87sr 86sr record around k t the concentration of dissolved sr and its 87sr 86sr has been measured in the headwaters of the krishna river system and west flowing western ghat rivers all of which have their drainage almost entirely in the deccan traps the sr concentration follows that of ca and mg with sr ca and sr mg ratios similar to that of deccan basalts suggesting that all these alkaline earths are released to waters nearly congruently from the deccan basalts during chemical weathering the 87sr 86sr range from 0 70614 to 0 70986 within that reported for the deccan basalts the dissolved sr flux from the deccan calculated from the measured data is 1 35 108 moles yr 1 0 4 of the global riverine flux which is nearly the same as the proportion of area covered by deccan basalts relative to the global drainage the flux however is a factor of 3 lower than that reported for the narmada tapti wainganga ntw rivers draining the northern deccan this difference in sr flux among rivers draining the various regions of deccan could be natural spatial temporal variations and or due to supply of sr to ntw rivers from nonbasaltic sources model calculations on the role of emplacement and weathering of deccan on marine sr isotope evolution around ktb and late tertiary show that deccan basalts can be an important contributor to the decline in 87sr 86sr during these periods it is shown that to account for the pre ktb dip in 87sr 86sr the flux requirement from deccan at that time would have to be several times the contemporary flux with 87sr 86sr of 0 705 0 708 considering that the area of deccan at ktb was about thrice the present area and that the weathering rate of deccan basalts may have been much higher in early stages following eruption such high fluxes at about ktb seem feasible the disproportionately higher flux requirement for sr is similar to that invoked to explain the pre ktb decrease in 187os 188os the calculations also show that the supply of unradiogenic sr from basalts can have significant control on the long term 66 to 55 ma decline of marine 87sr 86sr

magnetostratigraphical dating of loess deposits in china the age of chinese loess deposits has long been disputed biostratigraphical and earlier magnetostratigraphical investigations placed the entire loess formation within the pleistocene the new palaeomagnetic measurements reported here on a bore hole section near lochuan shaanxi province suggest a clearly defined magnetic polarity zonation which extends below the olduvai subchron a late pliocene age of 2 4 myr is assigned to the oldest loess sediments measured the intensity variations of natural remanent magnetization nrm and low field magnetic susceptibility are indicative of climatic changes during loess deposition

strontium isotopes as tracers of ecosystem processes theory and methods abstract the strontium sr isotope method can be a powerful tool in studies of chemical weathering and soil genesis cation provenance and mobility and the chronostratigraphic correlation of marine sediments it is a sensitive geochemical tracer applicable to large scale ecosystem studies as well as to centimeter scaled examination of cation mobility within a soil profile the 87sr 86sr ratios of natural materials reflect the sources of strontium available during their formation isotopically distinct inputs from precipitation dryfall soil parent material and surface or groundwater allow determination of the relative proportions of those materials entering or leaving an ecosystem the isotopic compositions of labile soil exchange complex and soil solution strontium and sr in vegetation reflect the sources of cations available to plants strontium isotopes can be used to track the biogeochemical cycling of nutrient cations such as calcium the extent of cation contributions from in situ weathering and external additions to soil from dust and rain can also be resolved with this method in this paper we review the geochemistry and isotopic systematics of strontium and discuss the use of this method as a tracer of earth surface processes

sr and nd isotopes in river sediments from the ganga basin sediment provenance and spatial variability in physical erosion 1 sr and nd concentrations and isotope compositions in sediment of the ganga river from gangotri to rajmahal and its tributaries have been measured to determine provenance and the spatial variability in physical erosion among the ganga subbasins sr and nd in silicates range from 37 to 138 and from 10 to 36 g g with 87sr 86sr and nd of 0 7474 0 8428 and 25 5 to 15 5 respectively the results suggest that 65 of ganga mainstream sediments are derived from the higher himalayan crystallines highlighting intense physical erosion in this region the 87sr 86sr values of sediments in the gangetic plain show nearly identical trends during two seasons with a sharp and significant decrease at barauni downstream of gandak confluence this brings out the major impact of the sediment contribution from the gandak to the ganga mainstream model calculation suggests that about half of the ganga sediment at rajmahal is sourced from the gandak the erosion rates in the himalayan subbasins of the ganga range between 0 5 and 6 mm a where a is years with the gandak having the highest erosion rate high relief and intense precipitation over the headwater basins of the gandak appear to drive the rapid and focused erosion of this basin the results of this study and those in literature suggest that the eastern syntaxis brahmaputra the western syntaxis indus and the gandak have much higher physical erosion rates than the other himalayan basins focused erosion in the hot spots of these river basins contributes significantly to the global riverine sediment budget and influence regional tectonics

the importance of solar insolation on the temperature variations for the past 110 kyr on the chinese loess plateau abstract the late quaternary temperature history on the chinese loess plateau clp is little known due to the absence of suitable paleothermometers here we present a quantitative temperature record for the last 110 kyr from lantian county southern clp based on the distributions of bacterial tetraethers lantian loess temperature variations display significant correlation with the northern hemisphere insolation 35 n as well as the cave monsoon records at the precession band we attribute such correlation to both the latent heat release from the east asian summer monsoon and the direct influence of sun s sensible heat over the semi arid landscape the long term cooling during the marine isotope stage mis 3 and the modest temperature drop of 5 c from 79 to 65 ka are best explained by interactions among multiple climate forcings including insolation atmospheric co 2 concentration global ice volume and regional glacier activities the cold and modestly wet climate during mis 3 may have promoted maximum regional glacial advances whereas the minimal temperature during local lgm reduced moisture transfer and led to glacial recession the unusually early deglacial warming at 22 5 ka highlights the importance of regional climate records to decipher the complex continental climate dynamics

silica secreting biota and mass extinctions survival patterns and processes abstract high survival and at least regional blooms of siliceous marine groups with coeval retreat of calcareous organisms is known from the frasnian famennian radiolarians silicisponges and end cretaceous diatoms radiolarians mass extinctions a strictly actualistic approach to the palaeoecology of silica secreting biota is of limited significance especially for silica enriched and oligotrophic palaeozoic epeiric seas and in particular during biotic turnovers adaptation among silica secreting marine plankton has led toward more efficient utilization of shrinking dissolved silica resources within surface waters of cenozoic oceans as shown by both radiolarians and diatoms this biosiliceous signal during the major biotic crises is mostly explained by a large scale increase in volcano hydrothermal activity during major plate boundary re arrangements triggering global ecosystem perturbations the cumulative stimulus favoured siliceous versus calcareous biota growth deposition and preservation because of 1 a higher rate of input of silica and other nutrients promoting eutrophication pulses 2 a punctuated or reversed greenhouse climatic effect episodically coupled with 3 vigorous oceanic circulation due to a variety of volcanogenic upwellings and turnovers siliceous communities adapted to more eutrophic conditions have thrived in the stressed niches on the other hand expanding anoxia and nutrification may lead to a stepwise loss of deep water niches and consequent selective decline of more specialized oligotrophic radiolarians and other pelagic biota by contrast siliceous faunas experienced severe non selective losses during the end permian mass extinction recorded as a chert gap thus the greatest environmental disaster of the phanerozoic was driven by a unique set of killing factors extremely effective for radiolarian productivity e g due to the combination of a drastic volcanic winter with expanding superanoxia

a novel proxy for terrestrial organic matter in sediments based on branched and isoprenoid tetraether lipids we propose a novel tracer for terrestrial organic carbon in sediments based on the analysis of tetraether lipids using high performance liquid chromatography mass spectrometry hplc ms analysis of terrestrial soil and peats shows that branched tetraether lipids are predominant in terrestrial environments in contrast to crenarchaeol the characteristic membrane lipid of non thermophilic crenarchaeota which is especially abundant in the marine and lacustrine environment based on these findings an index was developed the so called branched and isoprenoid tetraether bit index based on the relative abundance of terrestrially derived tetraether lipids versus crenarchaeol this bit index was applied to surface sediments from the angola basin where it was shown to trace the outflow of the congo river furthermore analyses of particulate organic matter from the north sea showed relatively higher bit indices in water column particulate organic matter near large river inputs a survey of globally distributed marine and lacustrine surface sediments shows that the bit index in these environments correlates with the relative fluvial input of terrestrial organic material making this index generally applicable the new proxy allows the rapid assessment of the fluvial input of terrestrial organic material in immature sediments up to 100 ma old

a 15 ka ph record from an alpine lake in north china derived from the cyclization ratio index of aquatic brgdgts and its paleoclimatic significance abstract a well dated sediment core from an alpine lake in north china gonghai lake was used for analysis of branched glycerol dialkyl glycerol tetraether lipids brgdgts based on the cyclization ratio index cbt of the brgdgts and using different terrestrial and lacustrine cbt ph empirical relationships the reconstructed ph records over the past ca 15 ka exhibited similar trends of variation although the absolute ph values were different in order to better understand the reconstructed ph record samples of surface soils from the dust source area and the catchment of gonghai lake as well as surface sediments from the lake were collected for instrumental ph measurements and modern brgdgt analysis the instrumental ph results demonstrated that the surface soils from the dust source area were alkaline while those from the catchment of gonghai lake were acidic in addition the instrumental ph results for the surface sediments from the lake were slightly alkaline and the corresponding ph values were intermediate between those of the two surface soil source groups this may reflect the effect of the input of material from different sources on the sedimentary ph record however the results from modern brgdgts in some of the surface soils and surface sediment samples demonstrate that brgdgts in the core sediments from gonghai lake are predominantly of aquatic origin therefore the cbt derived ph record over the past ca 15 ka from the lake can be interpreted as a record of the lake water ph history which is consistent with the carbonate content record from a parallel core from the same lake in addition using the modern lacustrine calibration the cbt derived ph values for surface sediments of gonghai lake are consistent with instrumental modern lake water ph values for the lake further comparison indicates that the lake water ph is controlled mainly by the degree of humidity of the local climate which is closely related to the intensity of the east asian summer monsoon easm therefore the ph record can be used as an indicator of easm intensity our results demonstrate that on the basis of careful analysis of its origins the cbt index of aquatic brgdgts can be used for lake water ph reconstruction and subsequent paleoclimate reconstruction and that in north china the lake water ph is controlled mainly by the degree of humidity of the local climate

strontium in rainwater from israel sources isotopes and chemistry abstract eighteen rain samples from israel have been analyzed for their chemical composition and87sr 86sr ratios the sr isotopic ratios lie in the range 0 7078 and 0 7092 and the sr concentrations vary from 1 10 4 to 9 10 4 meq sr l soluble salts in rainwater are inherited from three major natural sources seaspray recent marine minerals and mineral dust eroded from rock outcrops and soil a mixing model is formulated to apply the chemical composition of rain cl and sr2 and its isotopic87sr 86sr ratio for the identification and estimation of the sr sources all the samples fall within the mixing space predicted by the model for the three end members mentioned above the data indicate that the most important non seaspray source contributing dissolved salts to the rains in israel comprises a mixture of senonian to eocene chalk and its weathering products and recent marine minerals from local and imported sources most of the samples 67 contain 50 or more non seaspray sr i e sr dissolved from dust or recent marine minerals whereas 56 of the samples display87sr 86sr ratios lower than 0 7090 the rest represent mixtures of seaspray and recent marine minerals

radiolarian palaeoecology and radiolarites is the present the key to the past abstract radiolarian productivity pulses and related radiolarite deposition are phenomena difficult to understand from an exclusively actualistic viewpoint evolutionary selection pressure among silica secreting marine plankton both radiolarians and diatoms has led toward more economic usage of rapidly shrinking nutrient resources including dissolved silica of the photic zone in the late cenozoic oceans and in particular a substantial modification of oceanic cycle by the diatom explosive radiation even if there is a proved link between biomineralization and dissolved silica loading among the phytoplankton only the relative independence of modern siliceous planktic biotas from the available silica pool reflects mainly their progressive physiological specialisation during evolutionary history oceanic chemistry and productivity as well as patterns of circulation upwelling have changed radically during the phanerozoic radiolarites apparently represent an anachronistic facies as exemplified by their long lived and ocean wide distribution in palaeo pacific and hitherto highlighted actualistic models of localized intra oceanic wind driven upwelling loci are of largely questionable applicability in addition to plate drift hypersiliceous domains and intervals are explainable mostly by a large scale volcano hydrothermal activity during major plate boundary reconfigurations which in many ways favoured siliceous biotas acme and their skeletal remains accumulation and preservation factors tied to rapid voluminous submarine eruptions such as thermal buoyant megaplumes and basin overturns offer a viable alternative for traditional climatic circulation scenarios in case of hypersiliceous high productivity events irrelevant to greenhouse to icehouse climatic change the evolving carbon and silica cycles were coupled through the greenhouse effect and enhanced chemical weathering volcano hydrothermal and tectonic uplift events related mostly to extensive rifting and or accelerated oceanic spreading were the endogenous driving force that created this perturbation of the exogenous system the present biogeochemical cycle is representative only for the overall silica depleted post eocene oceanic ecosystems which broadly correlates with a major expansion of diatoms groups extremely efficient in silica removal and closely linking the silica budget with phosphorus and nitrogen cycles thus an orthodox uniformitarian approach to biosiliceous sedimentation based on a silica starved vigorous ocean is of limited significance when applied to the pre neogene settings especially in the peculiar planktic habitats of epeiric seas as well as during biotic crises marked by strong geotectonic overprint the major turnovers in marine siliceous biota composition in particular after the end permian radiolarite gap may have been coupled with discernible changes in an increasing biological control on the long term oceanic silica cycling punctuated equilibrium the evolutionary turnovers have induced a stepdown decrease of dissolved silica levels through the phanerozoic contemporaneously with the general secular trend of upward scaling of nutrient related ecological processes and increased effectiveness of resource utilization

palaeoceanography of organic rich rocks of the loma chumico formation of costa rica late cretaceous eastern pacific the late cretaceous late cenomanian campanian loma chumico formation consists of laminated to massive bedded siliceous shales cherts ash fall tuffs volcanic glass beds and volcaniclastic sandstones the loma chumico formation is at least 630 m thick core data in the tempisque basin and can be subdivided in the subsurface into organic rich and organic lean total organic carbon 1 facies rock eval total organic carbon toc data show that toc in the organic rich facies averages 15 5 with values as high as 33 inorganic geochemical petrological and sedimentological analyses indicate that all the lithologies of the loma chumico formation were deposited in middle shelf to outer slope environments adjacent to an active subaerial island arc the organic geochemistry and palaeontology of the loma chumico formation help constrain the factors that controlled biological productivity in the region during the late cretaceous biomarkers identified in organic rich facies by gas chromatography mass spectrometry gc ms show a high abundance of total steranes relative to hopanes in the morote 1 core indicating algal dominated organic input the hopane to sterane ratio of the extract from the manzanillo 1 core indicates a relatively high bacterial component to the organic matter upwelling and extrusive volcanism were the most important factors that controlled nutrient supply including silica flux and biological productivity within the loma chumico formation depositional system episodic radiolarian dinoflagellate or diatom blooms instigated by rapid infusions of volcanogenic silica may have resulted in expansion of the oxygen minimum zone omz enhancing the preservation of organic matter productivity appears to have been uniform even during deposition of the organic lean facies the findings of this study suggest that ocean wide anoxia in the eastern pacific was unlikely during the late cretaceous high toc contents of organic rich radiolarites from central caribbean deep sea drilling project dsdp sites may be related to upwelling produced in the eastern pacific by convergence of the easterly trade winds eastern pacific equatorial upwelling zone or may be part of a more complex pacific atlantic ocean interaction the end of deposition of organic rich rocks began near the end of the latest santonian earliest campanian in the central caribbean and costa rica palaeoceanographic models suggest that improved circulation and ventilation of bottom waters due to early opening of the north atlantic south atlantic seaway may explain this observation this may represent the influx of a previously unrecognized source of colder oxygenated intermediate bottom water proto antarctic intermediate water into the late cretaceous central atlantic and eastern pacific oceans

bacterial tetraether membrane lipids in peat and coal testing the mbt cbt temperature proxy for climate reconstruction abstract peatlands are widespread and important natural archives of environmental change here we explore the potential of the recently introduced mbt cbt proxy methylation index and cyclisation ratio of branched tetraethers to estimate past annual mean air temperature mat based on the distribution of bacterially derived branched glycerol dialkyl glycerol tetraether gdgt membrane lipids in peat and coal to this end branched gdgts in an ombrotrophic peat bog from switzerland and three coal deposits of increasing maturity were analysed for the surface of the bog reconstructed annual mat is higher than both measured annual mat and measured in situ pore water temperature changes in the cbt ratio considered a proxy for ph with depth in the bog do not match with present day in situ pore water ph but coincide with a peat stratigraphic boundary this indicates that gdgts down the bog profile are predominantly fossil and not derived from extant biomass the mbt cbt derived annual mat record also shows a large drop at this stratigraphic boundary which likely relates to past change in trophic status of the bog branched gdgts are abundant in an immature lignite vitrinite reflectance r o 0 25 but occur in low amount in a slightly more mature coal r o 0 32 annual mat could be reconstructed for the lignite alone and is higher than other proxy based estimates from approximately the same time and location our results indicate potential for the application of the mbt cbt proxy in peat and immature coals but improved constraints on the effects of different types of peat on branched gdgt distributions as well as improved calibration of mat estimates are needed before the method can be confidently applied

carbon isotopic composition of branched tetraether membrane lipids in a loess paleosol sequence and its geochemical significance abstract carbon isotopes of organic matter have been widely used in quantitative reconstruction of paleovegetation and paleoclimate since they are sensitive to vegetation and environmental changes however the effect of transformation of soil organic matter after burial remains unclear the carbon isotopes of brgdgts which were likely produced by heterotrophic bacteria in soil or peat provide an opportunity to fill this gap in this study we investigated the stable carbon isotopic composition of brgdgt derived alkane spanning the last 60 kyr in the lantian loess paleosol sequence from the southern chinese loess plateau as well as its relationship with 13c values of total organic carbon toc and other established climatic proxies the results show that the 13c values of brgdgts were slightly depleted ca 1 2 relative to toc and a good linear relationship between them was observed these support a heterotrophic lifestyle of brgdgt producing bacteria and suggest that 13c values of brgdgts may have potential use in paleovegetation reconstruction the similar variations between 13c values of brgdgts and toc in the soil core also suggest that the effect of soil organic matter transformation after burial may have limited impact on the environmental significance of 13c values of toc in comparison with 13c values of the toc the widely used proxy for past vegetation changes the 13c values of brgdgts seem more specific and sensitive in the lantian profile due to its specific origin and stable chemical structure

distributions of branched gdgts in soils and lake sediments from western uganda implications for a lacustrine paleothermometer bacterially produced branched glycerol dialkyl glycerol tetraethers gdgts are ubiquitous in soils and lake sediments and can potentially be used to reconstruct past temperatures in lakes however it is still unclear if these compounds are derived from eroded soils or if they are produced in situ to better understand environmental controls on the distributions of these compounds and the sources of branched gdgts to lake sediments we compare branched gdgt distributions and concentrations in lake sediments and catchment soils within a 3600 m altitudinal transect in western uganda reconstructed mean annual air temperature maat determined from the degree of methylation mbt and cyclisation cbt of branched gdgts in soils decreases with increasing altitude as is expected from the air temperature gradient in our transect however we observe significant offsets between observed and reconstructed temperatures in soils from wet high elevation soils but not in most dry low elevation soils branched gdgt distributions differ significantly between lake sediments and soils at all elevations with greater differences at low elevations than at high elevations these data support previous hypotheses that branched gdgts are produced in situ in lakes and suggest that the abundance of water in soil environments may play a role in controlling the distribution of branched gdgts while branched gdgts in lacustrine sediments can be used to reconstruct temporal temperature variations in lakes we urge caution in utilizing this proxy in lacustrine systems with high soil loadings especially if there is evidence of changing clastic fluxes through time

dune sand transport as influenced by wind directions speed and frequencies in the ordos plateau china the ordos plateau in china is a region with extensive wind erosion severe desertification and various aeolian sand hazards in order to determine aeolian sand transport in this region the relationship between the sand transport rate and wind speed at 10 min frequencies was established by field observation in both the qubqi sand desert and the mu us sandy land threshold wind speeds 2 m above the ground for mobile semi fixed and fixed dune surfaces were estimated by field observations the sand transport rate increased with the increase of the bare land ratio and near bed wind speed high resolution meteorological 10 min average wind velocity data at 10 m above the ground were converted into velocity values at a height of 2 m to calculate sand transport potential based on three specific parameters decisive for sand transport wind speed duration and direction the quantity of aeolian sand transported was calculated for various wind speed levels and directions and the overall characteristics of sand transport on different dune surface types were determined by vector operation techniques sand transporting winds took place mainly in springtime the prevailing wind directions were w wnw and nw with a frequency of more than 60 in total and sand transport in these directions made up more than 70 of the total transport corresponding to a general southeastward encroachment of aeolian sand in the study area the relationship between wind frequency and speed can be expressed by a power function high magnitude strong winds had a low frequency but they played a dominant role in aeolian sand transport

decoupled warming and monsoon precipitation in east asia over the last deglaciation our understanding of the continental climate development in east asia is mainly based on loess paleosol sequences and summer monsoon precipitation reconstructions based on oxygen isotopes delta o 18 of stalagmites from several chinese caves based on these records it is thought that east asian summer monsoon easm precipitation generally follows northern hemisphere nh summer insolation however not much is known about the magnitude and timing of deglacial warming on the east asian continent in this study we reconstruct continental air temperatures for central china covering the last 34 000 yr based on the distribution of fossil branched tetraether membrane lipids of soil bacteria in a loess paleosol sequence from the mangshan loess plateau the results indicate that air temperature varied in phase with nh summer insolation and that the onset of deglacial warming at similar to 19 kyr bp is parallel in timing with other continental records from e g antarctica southern africa and south america the air temperature increased from is c at the onset of the warming to a maximum of 27 degrees c in the early holocene similar to 12 kyr bp in agreement with the temperature increase inferred from e g pollen and phytolith data and permafrost limits in central china comparison of the tetraether membrane lipid derived temperature record with loess paleosol proxy records and stalagmite 5180 records shows that the strengthening of easm precipitation lagged that of deglacial warming by ca 3 kyr moreover intense soil formation in the loess deposits caused by substantial increases in summer monsoon precipitation only started around 12 kyr bp ca 7 kyr lag our results thus show that the intensification of easm precipitation unambiguously lagged deglacial warming and nh summer insolation and may contribute to a better understanding of the mechanisms controlling ice age terminations

dune mobility and aridity at the desert margin of northern china at a time of peak monsoon strength wind blown sands were mobile at many sites along the desert margin in northern china during the early holocene 11 5 8 ka ago based on extensive new numerical dating this mobility implies low effective moisture at the desert margin in contrast to growing evidence for greater than modern monsoon precipitation at the same time in central and southern china dry conditions in the early holocene at the desert margin can be explained through a dynamic link between enhanced diabatic heating in the core region of the strengthened monsoon and increased subsidence in drylands to the north combined with high evapotranspiration rates due to high summer temperatures after 8 ka ago as the monsoon weakened and lower temperatures reduced evapotranspiration eolian sands were stabilized by vegetation aridity and dune mobility at the desert margin and a strengthened monsoon can both be explained as responses to high summer insolation in the early holocene

correlations between microbial tetraether lipids and environmental variables in chinese soils optimizing the paleo reconstructions in semi arid and arid regions the bacterial membrane lipid based continental paleothermometer the mbt cbt or mbt cbt proxy methylation index of branched tetraethers cyclization of branched tetraethers results in a large temperature deviation when applied in semiarid and arid regions here we propose new calibration models based on the investigation of 100 surface soils across a large climatic gradient with a particular focus on semiarid and arid regions of china and apply them to a loess paleosol sequence as reported elsewhere mbt values exhibit a much higher correlation with maat than with summer temperature suggesting a minimal seasonality bias however mbt is apparently insensitive to temperature 20 degrees c additional complexities are apparent in alkaline and arid soils which are characterized by different relationships to climatic parameters than those in the complete chinese or global dataset for example mbt and cbt indices exhibit a negative correlation in alkaline and arid soils in contrast to their positive correlation in acid soils moreover the cyclization ratio of bgdgts cbt previously defined as a proxy for soil ph is apparently primarily controlled by maat in these alkaline soils thus we propose 1 a local chinese calibration of the mbt cbt proxy and 2 an alternative temperature proxy for use in semiarid and arid regions based on the fractional abundances of bgdgts the latter has a markedly higher determination factor and lower root mean square error in alkaline soils than the chinese local calibration and is suggested to be preferred for paleotemperature reconstruction in chinese loess paleosol sequences these new bgdgt proxies have been applied to the weinan holocene paleosol section of the chinese loess plateau clp the fractional abundance calibration when applied in the weinan holocene paleosol produces a total holocene temperature variation of 5 2 degrees c and a temperature for the topmost sample that is consistent with the modern temperature previously we showed that the ratio of archaeal isoprenoid gdgts to bgdgts r i b increases at map 0 5 in the clp suggest the presence of enhanced aridity in the late holocene in north china in combination the high r i b ratios 0 5 and the associated low mbt values 0 4 reveal the co occurrence of dry and cold events especially in the latest holocene in the loess paleosol sequences in clp and probably also in cold and arid regions outside of clp c 2013 elsevier ltd all rights reserved

hydroclimatic variability in loess δd wax records from the central chinese loess plateau over the past 250 ka abstract this study reports hydrogen isotopic records from the central chinese loess plateau clp over the past 250 ka after eliminating the influence of ice and local temperatures the dwax records extracted from two loess sites at xifeng and luochuan can be taken to represent arid humid alternations in the hydrological environment in this marginal asian summer monsoon asm region they also contain integrated information on summer precipitation patterns and the corresponding responses to these changes by predominant vegetation cover types these arid humid alternations show 100 ka 40 ka and 20 ka cycles an increase in precipitation in association with an enhanced summer monsoon has historically been taken to be the major factor driving a humid environment in the central clp however hydroclimatic changes in dwax records differ for the central clp central china and southern china over a 20 ka cycle the influence of solar insolation on hydroclimatic changes can be shown to be consistent throughout the central clp however changes in the relative location of the land and sea may have caused different hydroclimatic responses between southern china and the central clp on a glacial interglacial scale the hydroclimatic variability in the central clp would suggest that an enhanced summer monsoon due to climatic warming is the key to understanding decreased drought degree in this marginal monsoonal region

branched and isoprenoid tetraether bit index traces water content along two marsh soil transects surrounding lake qinghai implications for paleo humidity variation abstract the bit index represents the relative abundances of branched glycerol dialkyl glycerol tetraethers bgdgts and the isoprenoid gdgt crenarchaeol while bgdgts are produced mainly by soil anaerobic bacteria crenarchaeol is known to be a biomarker for aerobic ammonia oxidation by chemolithoautotrophic thaumarchaeota particularly in the open ocean or lakes thus the index in marine and lacustrine settings has been widely used as a proxy for soil input here we have investigated gdgt distribution along two transects extending from the lake shore marsh to upland soils on the ne qinghai tibetan plateau the results show that soil water content swc correlates positively with concentration of bgdgts and negatively with concentration of crenarchaeol consequently there is a significant positive correlation between swc and the bit index our study highlights a new potential application of bit as a humidity proxy in loess soil and peat deposits

chert in the iberian pyrite belt since lenses of chert are common within the volcano sedimentary succession hosting the massive sulphide deposits of the iberian pyrite belt spain and portugal we examined numerous chert occurrences both petrographically and geochemically to test their possible value for massive sulphide exploration the chert is found at two main lithostratigraphic levels upper and lower that are also interpreted as massive sulphide bearing in both cases the chert is located at the top of acidic volcanic sequences or in the associated sediments we have not been able to observe the relationships between massive sulphides and chert but some of the large orebodies of the province lousal la zarza tharsis planes san antonio body of rio tinto neves are described as being locally capped by chert facies four main types are recognized among the chert and associated facies 1 red hematitic chert magnetite 2 radiolarian and or sedimentary textured conglomeratic chert with hematite and or mn oxides 3 pale sulphidic chert 4 rhodonite and or mn carbonate magnetite facies in the spanish part of the province the radiolarian chert is confined to the upper level the distribution of the other types appears to be haphazard the hydrothermal origin of the south iberian chert is shown by its high fe mn and low co ni cu contents the presence of small positive ce anomalies indicates a shallow marine environment shelf or epicontinental sea which is consistent with the volcanological and sedimentological data the chert was emplaced below the sea floor through chemical precipitation and or through alteration and replacement of the country rock residual traces of which are ghost phenocrysts and high al ti and rare earth contents macro and microscopic relationships indicate that the oxide facies hematite magnetite formed first probably providing a protective insulating cover against the marine environment and enabling an evolution towards sulphide facies a phase of mn carbonate and silicate quartz chlorite sulphides appears to be even later it was not possible through discrimination to isolate a chert that could be considered as representing a lateral marker of massive sulphides moreover both field observations and geochemical data seem to indicate a relative independence of this siliceous sulphide hydrothermal activity from the hydrothermal activity giving rise to the massive sulphides such is also indicated by the lead isotopic signature of the chert which is appreciably more radiogenic than that of the massive sulphides the lead enrichment in the sulphidic chert facies indicates the participation of a different source sediments sea water from that of the massive sulphides the hypothesis of an independent hydrothermal chert event can thus be envisaged wherein the chert reflects submarine low temperature hydrothermal activity that is most apparent during a break within the volcano sedimentary succession and which may locally have competed with the high temperature hydrothermal activity giving rise to the massive sulphides the interest of the chert thus rests in its palaeodynamic significance as a marker of periods of volcanic quiescence and in its possible role as a protective insulating cap favourable to the deposition of massive sulphides

mid late holocene temperature and precipitation variations in the guanting basin upper reaches of the yellow river abstract the reconstruction of prehistoric temperature and precipitation variations in the upper reaches of the yellow river is essential for understanding the cultural evolution of the region but related information is sparse due to the limitations of the available proxies recent studies have shown that microbial glycerol dialkyl glycerol tetraethers gdgts are promising tools for reconstructing mean annual temperature mat and mean annual precipitation map in terrestrial deposits in this study we reconstructed mid late holocene climatic changes using gdgt distributions in a loess paleosol sequence in the lajia ruins of the neolithic qijia culture guanting basin in the southwestern end of the chinese loess plateau our gdgt records show that map decreased from ca 600 mm to 430 mm while mat decreased from 11 9 c to 8 0 c during the past ca 7000 yr and a drastic decline in map 70 mm accompanied by a 0 8 c decline in mat occurred at 3800 3400 yr bp our results provide direct evidence supporting a hypothesis that the flourishing 4200 4000 yr bp and decline 4000 3600 yr bp of the qijia culture mainly based on millets cultivation and subsequent rise of the xindian kayue culture 3600 2600 yr bp based on mixed agriculture of sheep husbandry and millets cultivation were triggered by climate change

chemical and sr isotopic compositions of rainwater on the ordos desert plateau northwest china the major ions and sr concentrations and the sr isotopic compositions of rainwater from four weather stations in the ordos desert northwest china were measured in this study in the studied rainwater ca2 was the most abundant cation with a volume weighted mean vwm value of 387 mol l and so4 2 was the dominant anion with a vwm value of 229 mol l the sr concentrations varied from 0 1 to 72 mol l and the strontium isotopic ratios 87sr 86sr range from 0 7098 to 0 7110 with an average of 0 7106 which are higher than that of seawater the 87sr 86sr ratios showed the potential to trace sources of rainwater solutes when combined with other chemical composition data the covariation between mg ca vs ca na and sr isotopic ratios vs ca sr in the rainwater suggested the mixture of at least three sources soil dust derived from the local area and or desert and loess areas in northwest china 87sr 86sr values of 0 7114 seawater 87sr 86sr value of 0 70917 and anthropogenic inputs 87sr 86sr value of 0 7110 and high ca sr due to coal combustion or automobile exhausts the human activity inputs are likely the major sources of atmospheric contaminants in the ordos rainwater from back trajectory analysis principal component analysis and a comparison between the major ion compositions of other selected sites in china we conclude that the ordos rainwater ion composition is more significantly influenced by desert and soil dust and anthropogenic sources primarily industrial and traffic emissions from the surrounding cities than by marine sources

tectonic processes in papua new guinea and past productivity in the eastern equatorial pacific ocean phytoplankton growth in the eastern equatorial pacific ocean today accounts for about half of the new production the fraction of primary production fuelled by externally supplied nutrients in the global ocean the recent demonstration that an inadequate supply of iron limits primary production in this region1 supports earlier speculation that in the past fluctuations in the atmospheric deposition of iron bearing dust may have driven large changes in productivity2 but we argue here that only small 2 nm increases in the iron concentration in source waters of the upwelling equatorial undercurrent are needed to fuel intense diatom production across the entire eastern equatorial pacific ocean episodic increases in iron concentrations of this magnitude or larger were probably frequent in the past because a large component of the undercurrent originates in the convergent island arc region of papua new guinea which has experienced intensive volcanic erosional and seismic activity over the past 16 million years cycles of plankton productivity recorded in eastern equatorial pacific sediments may therefore reflect the influence of tectonic processes in the papua new guinea region superimposed on the effects of global climate forcing

influence of oceanic anoxic events on the evolution of mid cretaceous radiolaria in the north atlantic and western tethys abstract mid cretaceous aptian turonian extinction radiation events of radiolaria from the north atlantic and western tethys are summarized in relation to oceanic anoxic events oae from investigations of radiolarian faunas black shales and stable carbon isotopes extinction and radiation events of radiolaria can be observed from the late early aptian the earliest albian the latest albian and the cenomanian turonian boundary these events correlate well with organic carbon rich sediments that contain type ii kerogen and show positive 13c excursions they correspond to the oceanic anoxic events oae in the early aptian oae 1a selli level early albian oae 1b late albian oae 1d and latest cenomanian oae 2 bonarelli level detailed investigations of the two most significant events the selli and the bonarelli level in the umbria marche basin of central italy show that extinctions coincide with the first occurrence of marine black shales type ii kerogen and the most prominent rise of 13corg values stepwise extinctions and continuous radiations precede and follow the events similar patterns are evident for the oae 1b and 1d black shales dominated by terrestrial organic matter type iii kerogen e g oae 1c are not characterized by isotopic excursions or by radiolarian extinction radiation events contemporaneous drowning events documented from carbonate platforms around the investigated basins provide a link to a model where flooding of lowlands and leaching of nutrients during a relative rise of sea level lead to an increased productivity and an expansion of the oxygen minimum zone omz because of the loss of deep habitats deeper dwelling forms become extinct shallower dwelling radiolarians survive a narrowing of the omz during highstands and relative sea level falls together with a coupled decrease of the nutrient supply leads to the development of new niches and therefore to radiation

hydrogen isotopic compositions along a precipitation gradient of chinese loess plateau critical roles of precipitation evaporation and vegetation change as controls for leaf wax δd abstract the hydrogen isotopic compositions d of long chain plant leaf waxes can reflect changes of continental hydrology and thus have been increasingly utilized for paleoclimate reconstruction one of the unresolved major issues is whether variations of leaf wax d dwax signals along a precipitation gradient reflect changes of precipitation d precipitation amount and or evapo transpiration this ambiguity limits our interpretation of dwax in geological records as well as the quantitative reconstruction of paleohydrological variability here we systematically investigated d of soil water and waxes extracted from soil and plant leaves in the chinese loess plateau clp and its surrounding areas along a precipitation gradient with mean annual precipitation map varying from 140 mm to 676 mm the results showed that while the variation of modeled precipitation d has no significant correlation with map soil water d soil dwax and individual plant dwax exhibit negative correlations with map in relatively arid areas the d values of soil water and plant leaf waxes are significantly more positive due to much lower precipitation relative to evapo transpiration suggesting that effective precipitation p e ratio has played a crucial role in the d enrichment of soil and plant leaf waxes in this region while parallel decreasing trends in dwax are found along the increase of precipitation gradient among dominant plants including artemisia spp aster hispidus stipa bungeana and cleistogenes squarrosa in the region with similar slopes the large d offsets between plant groups suggest that plant type is an important factor in controlling plant hydrogen isotope fractionations our results indicate that dwax preserved in paleosols can be used to infer past conditions of water availability in arid and semi arid inland regions but with a mechanism that is different from the influence of amount effect in humid areas moreover vegetation changes should be constrained by independent paleobotanical data before monsoon related paleohydrology in the clp and its surrounding areas can be quantitatively reconstructed using the plant wax d proxy

late cretaceous oceans and the cool tropic paradox oxygen isotopic proxies of paleo sea surface temperatures ssts suggest that maastrichtian about 66 million years ago tropical ssts were lower than those of today they also demonstrate that maastrichtian latitudinal sst gradients were much lower than those of the present the low maastrichtian sst gradients indicate that meridional heat transport was much greater or latitudinal differences in the balance of radiation to and from the sea surface were much less extreme during the latest cretaceous than they are today or that both conditions were true these findings challenge traditional interpretations of greenhouse late cretaceous climates

seawater sr isotope variation over the past 300 kyr and influence of global climate cycles the past 300 000 years have been characterized by glacial inter glacial fluctuations accompanied by glacio eustatic changes in sea level and changes in continental erosion arising from varying low latitude rainfall and river drainage here we use measurements of strontium isotopes in foraminifera and corals to place limits on variations in the sr isotope composition of sea water in response to these changing inputs we find small variations of about 20 p p m in the 87sr 86sr ratio which for the foraminiferal record seem to follow a cycle close to the 100 kyr periodicity seen for a number of other climate related phenomena these are superimposed on a general increase in87sr 86sr through the cenozoic to the present on short timescales these changes are likely to be controlled by variations in the global riverine sr flux and thus by weathering rates rather than in the hydrothermal sr flux at mid ocean ridges we show that transient variations over a 50 kyr timescale can be explained on the basis of the present day global drainage system in conjunction with the perturbations expected to accompany climate changes over the past 300 kyr

distribution of tetraether lipids in the 25 ka sedimentary record of lake challa extracting reliable tex86 and mbt cbt palaeotemperatures from an equatorial african lake the distribution of isoprenoid and branched glycerol dialkyl glycerol tetraether gdgt lipids was studied in the sedimentary record of lake challa a permanently stratified partly anoxic crater lake on the southeastern slope of mt kilimanjaro kenya tanzania to examine if the gdgts could be used to reconstruct past variation in regional temperature the study material comprised 230 samples from a continuous sediment sequence spanning the last 25 ka with excellent age control based on high resolution ams c 14 dating the distribution of gdgts showed large variation through time in some time intervals i e from 20 4 to 15 9 ka bp and during the younger dryas 12 9 11 7 ka bp crenarchaeol was the most abundant gdgt whereas at other times i e during the early holocene branched gdgts and gdgt 0 were the major gdgt constituents in some intervals of the sequence the relative abundance of gdgt 0 and gdgt 2 was too high to be derived exclusively from lacustrine thaumarchaeota suggesting a sizable contribution from methanogens and other archaea this severely complicated application of tex86 palaeothermometry in this lake and limited reliable reconstruction of lake water temperature to the time interval 25 13 ka bp i e the last glacial maximum and the period of post glacial warming the tex86 inferred timing of this warming is similar to that recorded previously in two of the large african rift lakes while its magnitude is slightly or much higher than that recorded at these other sites depending on which lake based tex86 calibration is used application of calibration models based on distributions of branched gdgts developed for lakes inferred temperatures of 15 18 degrees c for the last glacial maximum and 19 22 degrees c for the holocene however the mbt cbt palaeothermometer reconstructs temperatures as low as 12 degrees c for a lateglacial period centred on 15 ka bp variation in down core values of the bit index are mainly determined by the varying production rate of crenarchaeol relative to in situ produced branched gdgts the apparent relationship of the bit index with climatic moisture balance can be explained either by the direct influence of lake level and wind strength on nutrient recycling or by influx of soil nutrients promoting aquatic productivity and nitrification this study shows that gdgts can aid in obtaining climatic information from lake records but that the obtained data should be interpreted with care

calibration and application of the branched gdgt temperature proxy on east african lake sediments branched glycerol dialkyl glycerol tetraethers brgdgts are a novel proxy for mean annual air temperature maat and have the potential to be broadly applicable to climate reconstruction using lacustrine sediments several calibrations have been put forth relating brgdgt distributions to maat using a variety of linear regressions including the methylation mbt and cyclization cbt indices of brgdgts the relative abundances of the major non cyclized brgdgts mbrgdgts and best subsets regression bsr of the fractional abundances of the nine most common brgdgts however these calibrations have rarely been applied to lake sediment cores to reconstruct temperatures and test the applicability of this proxy as a paleothermometer we present an expanded east african lakes surface sediment brgdgt dataset based upon 111 lakes and examine three methods of calibrating brgdgts to maat these methods include recalculations of the east african lake mbt cbt calibration and mbrgdgts calibrations as well as a new stepwise forward selection sfs calibration that uses the four combined brgdgts that explain the most variance in temperature in our calibration set we apply these new calibrations as well as five previously published lacustrine brgdgt calibrations to the brgdgt distributions of our surface sediment dataset and a 48 kyr sediment core from sacred lake mt kenya producing the first brgdgt temperature reconstruction available from a small tropical lake we compare the reconstructed temperatures to previously published paleotemperature records from east africa to help us assess the performance of the brgdgt calibrations we find that the sfs calibration has a consistently low root mean squared error of prediction rmsep over the entire range of maat while the mbt cbt and mbrgdgt calibrations have relatively large rmseps particularly between lakes with similar temperatures but variable ph this suggests that these techniques do not properly deconvolve the temperature and ph signals recorded in the distributions of the brgdgts we further find that only the sfs calibration produces a credible reconstructed temperature history from sacred lake when compared to other last glacial maximum paleotemperature estimates from east africa thus we advocate for the use of the sfs calibration when reconstructing paleotemperatures from brgdgts in east africa

are undiscovered hydrothermal vents in the southern red sea the main source of silica and helium 3 for the red sea deep water geochemical ocean sections study geosecs indian ocean expedition data show that silica and 3he in the red sea deep water are linearly correlated suggesting a common hydrothermal source silica sections for the red sea from the geosecs and mer rouge merou expeditions show a strong vertical silica maximum centered at 500 to 600 m depth the merou sections which have higher horizontal resolution than the geosecs sections suggest that the primary silica source lies in the south at that depth the interpretation is that the large scale silica and 3he distributions are due to the dispersal in the red sea deep water of warm or hot hydrothermal vent waters associated with the seafloor spreading center of the southern red sea the helium and silica rich hot brines of the central red sea probably cannot provide the large fluxes of silica or 3he required to maintain the inventory of either of these deep water properties in steady state the hypothesis of a common hydrothermal source for silica and 3he can most readily be tested by measurements of the germanium silicon ratio in red sea deep water

late quaternary dust flow on the chinese loess plateau abstract the dust flux of over 25 g cm2 103yr was reached in the central part of the chinese loess plateau during the last glacial maximum this is more than three times higher than during the last interglacial and early glacial time the grain size of the pleniglacial dust reached a peak shortly after 20 000 years ago and testifies to the occurrence of strong winds and frequent dust storms

multiple factors in the origin of the cretaceous tertiary boundary the role of environmental stress and deccan trap volcanism a review of the scenarios for the cretaceous tertiary k t boundary event is presented and a coherent hypothesis for the origin of the event is formulated many scientists now accept that the event was caused by a meteorite impact at chicxulub in the yucatan peninsula mexico our investigations show that the oceans were already stressed by the end of the late cretaceous as a result of the long term drop in atmospheric co2 the long term drop in sea level and the frequent development of oceanic anoxia extinction of some marine species was already occurring several million years prior to the k t boundary the biota were therefore susceptible to change the eruption of the deccan traps which began at 66 2 ma coincides with the k t boundary events it erupted huge quantities of h2so4 hcl co2 dust and soot into the atmosphere and led to a significant drop in sea level and marked changes in ocean temperature the result was a major reduction in oceanic productivity and the creation of an almost dead ocean the volcanism lasted almost 0 7 m y extinction of biological species was graded and appeared to correlate with the main eruptive events elements such as ir were incorporated into the volcanic ash possibly on soot particles this horizon accumulated under anoxic conditions in local depressions and became the marker horizon for the k t boundary an oxidation front penetrated this horizon leading to the redistribution of elements the eruption of the deccan traps is the largest volcanic event since the permian triassic event at 245 ma it followed a period of 36 m y in which the earth s magnetic field failed to reverse instabilities in the mantle are thought to be responsible for this eruption and therefore for the k t event we therefore believe that the k t event can be explained in terms of the effects of the deccan volcanism on an already stressed biosphere the meteorite impact at chicxulub took place after the onset of deccan volcanism it probably played a regional rather than a global role in the k t extinctions

simulation of co2 plume movement in multilayered saline formations through multilayer injection technology in the ordos basin china deep saline aquifers still remain a significant option for the disposal of large amounts of co2 from the atmosphere as a means of mitigating global climate change the small scale carbon capture and sequestration demonstration project in ordos basin china operated by the shenhua group is the only one of its kind in asia to put the multilayer injection technology into practice this paper aims at studying the influence of temperature injection rate and horizontal boundary effects on co2 plume transport in saline formation layers at different depths and thicknesses focusing on the variations in co2 gas saturation and mass fraction of dissolved co2 in the formation of brine in the plume s radial three dimensional field around the injection point and interlayer communication between the aquifer and its confining beds of relatively lower permeability the study uses the eco2n module of tough2 to simulate flow and pressure configurations in response to small scale co2 injection into multilayer saline aquifers the modelling domain involves a complex multilayer reservoir caprock system comprising of a sequence of sandstone aquifers and sealing units of mudstone and siltstone layers extending from the permian shanxi to the upper triassic liujiagou formation systems in the ordos basin simulation results indicate that co2 injected for storage into deep saline aquifers cause a significant pressure perturbation in the geological system that may require a long duration in the post injection period to establish new pressure equilibrium the multilayer simultaneous injection scheme exhibits mutual interference with the intervening sealing layers especially when the injection layers are very close to each other and the corresponding sealing layers are thin the study further reveals that injection rate and temperature are the most significant factors for determining the lateral and vertical extent that the co2 plume reaches and which phase and amount will exist at a particular time during and after the injection in general a large number of factors may influence the co2 water fluid flow system considering the complexity in the real geologic sequence and structural configurations therefore optimization of a co2 injection scheme still requires pursuance of further studies

chinese loess and the paleomonsoon abstract this paper presents a general review of the recent research advances of the east asian paleomonsoon based mainly on studies of the loess soil sequences in the chinese loess plateau in the last 2 6 million years the paleomonsoonal history may be divided into about 166 events on a time scale of the earth s orbital variations during the last glacial period millenial scale oscillations of the monsoon system were prominent which can be fairly well correlated with the dansgaard oeschger cycles recognized in the greenland ice cores the monsoonal rainfall belt has experienced a wide repeated advance retreat change during the glacial interglacial cycles of the pleistocene both temporal and spatial changes of the monsoon system in the quaternary could have been linked closely to global ice volume variations

sr isotopic and elemental characteristics of calcites in the chinese deserts implications for eolian sr transport and seawater sr evolution abstract calcite content sr concentrations and isotopes of calcites in the chinese deserts are systematically studied in this paper calcite contents which are calculated according to acid soluble ca contents in the deserts are generally higher in the sandy deserts than in the sandy lands and decrease roughly from northwest to northeast of china acid soluble sr is well correlated with calcite in the chinese deserts implying acid soluble sr comes mainly from the calcite dissolution sr concentrations in calcites calculated on the basis of calcite contents and acid soluble sr concentrations in the deserts have an inverse relation to calcite contents essentially mirroring the degree of sr substitution for ca in the calcite development desert calcites have regional variations in sr isotopic ratios calcite sr isotopic ratios depend on geological settings and chemical weathering the badain jaran and tengger deserts are probably affected by additional factors such as the remote groundwater cycle or overturning of underlying sand deposits only four deserts taklimakan qaidam badain jaran and tengger appear to be potential sources of eolian deposits in the chinese loess plateau clp isotopic signatures of calcite sr and silicate nd further indicate that the tengger desert was not an important source for eolian deposits in the clp eolian calcite was probably enriched due to wind sorting from the potential sources to the clp and suffered weathering leaching after it accumulated in the clp sr isotopic compositions and ca sr molar ratios of calcites are different between the deserts and the lingtai profile due to the integrated effect of wind sorting and weathering leaching it is essential to calculate accurately the 87sr 86sr ratio and sr concentration of eolian calcite entering the oceans according to geochemical data of the chinese deserts because of the importance of the chinese deserts in the global dust cycle the calculated sr concentration and 87sr 86sr ratio of eolian calcite entering the north pacific ocean are 11 75 mol g and 0 71032 respectively the calculated values in this study are close to the recommended values by jacobson jacobson a d 2004 has the atmospheric supply of dissolved calcite dust to seawater influenced the evolution of marine 87sr 86sr ratios over the past 2 5 million years geochem geophys geosyst 5 12 1 9 q12002 doi 10 1029 2004gc000750 using the same model as that of jacobson 2004 the effect of asia dust on the evolution of seawater sr isotopes is evaluated 87sr 86sr seawater increases by 0 3 10 5 if the lower dust flux of 2 34 108 mol sr yr is used in the model suggesting the little effect of asian dust on the seawater sr record in the quaternary the increase in 87sr 86sr seawater is 1 5 10 5 if the higher value of 1 17 109 mol sr yr is used as observed in the quaternary sr record these results further support the suggestions of jacobson 2004

variation in 6 methyl branched glycerol dialkyl glycerol tetraethers in lantian loess paleosol sequence and effect on paleotemperature reconstruction abstract the distribution of branched glycerol dialkyl glycerol tetraethers brgdgts has been increasingly used as a proxy in paleoclimate studies of marine lacustrine and loess environments a paleothermometer was subsequently quantified using a combination of the methylation and cyclization index of branched tetraethers mbt cbt on the basis that mbt was related to mean annual air temperature and to a lesser extent soil ph whereas cbt correlated only with soil ph as newly described 6 methyl brgdgts seemed to introduce a dependence on soil ph of this temperature proxy we investigated the effect of the 6 methyl brgdgts on an existing paleotemperature reconstruction we describe the evolution in temperature and ph recorded in the lantian loess paleosol sequence for the last 120 kyr using a new analytical method the results show that 6 methyl brgdgts were abundant comprising on average 26 of the total amount of brgdgts in the sequence the fractional abundance of 6 methyl brgdgts generally tracked the change in soil ph at the same soil section a considerable delay up to ca 7 kyr in the variation in fractional abundance of 6 methyl brgdgts vs that of 5 methyl brgdgts was observed possibly resulting from the different environmental factors to which they respond we also found that variation in the reconstructed mat values using different calibrations could be up to 7 c possibly due to soil moisture variation since soil moisture may have a significant impact on the distribution of brgdgts our results further indicate that early warming occurred on the southern chinese loess plateau relative to a monsoonal precipitation increase as reported elsewhere

late cretaceous and paroxysmal cretaceous tertiary extinctions the various geological signatures at cretaceous tertiary time including iridium and other associated elements microspherules and shock deformation features are compatible with the suggestion that the transition is marked by a period of intense volcanism the volatile emissions from this volcanism would lead to acid rain reduction in the alkalinity and ph of the surface ocean global atmospheric temperature changes and ozone layer depletion these environmental effects coupled with those related to the major sea level regression of the late cretaceous provide the framework for an explanation of the selective nature of the observed extinction record

oxygen 18 16 variability in greenland snow and ice with 10 3 to 105 year time resolution the 3 km long greenland ice sheet project 2 gisp2 ice core presents a 100 000 year detailed oxygen isotope profile covering almost a full glacial interglacial cycle measuranents of isotopic fluctuations in snow frost and atmospheric water vapor samples collected during summer field seasons up to 20 0 are compatible with the large and abrupt 80 160 changes observed in accumulated tim snow pit 15 80 profiles from the gisp2 summit area however show rapid smoothing of the 180 160 signal near the surface beyond about 2 m depth the smoothedi5180 signal is fairly well preserved and can be interpreted in terms of average local weather conditions and climate the longer climate fluctuations also have regional and often global significance in the older part of the record corresponding to marine isotope stages mis 5a to 5d the effect of orbital climate forcing via the 19 and 23 kyr precession cycles and the 41 kyr obliquity cycle is obvious from the end ofmis 5a at about 75 000 years b p till the end of the glacial at the younger dryas preboreal transition at 11 650 years b p the o180 160 record shows frequent rapid switches between intermediate interstadial and low stadial values fourier spectra of the oscillations that are superimposed on the orbitally induced changes contain a strong periodicity at 1 5 kyr a broad peak at 4 0 kyr and additional shorter periods detailed comparison of the gisp2 180 160 record with the vostok antarctica 15d record pacific ocean foraminiferal 180 160 grande pile france tree pollen and insolation indicates that a counterpart to many of the rapid 180 160 fluctuations of gisp2 can be found in the other records and that the gisp2 isotopic changes clearly are the local expression of climate changes of worldwide extent correlation of events on the independent gisp2 and specmap time scales for the interval 10 000 50 000 years b p shows excellent chronometric agreement except possibly for the event labeled 3 1 the glacial to interglacial transition evidently started simultaneously in the arctic and the antarctic but its development and its expression in greenland isotopes was later suppressed by the influence of meltwater especially from the barents sea ice sheet on deep water formation and ocean circulation meltwaters from different ice sheets bordering the north atlantic also influenced ocean circulation during the bolling allerod interstadial complex and the younger dryas and led to a distinct development of european climate and greenland 180 160 values the holocene interval with long term stable mean isotopic values contains several fluauations with periods from years to millennia dominant is a 6 3 year oscillation with amplitude up to 3 to 4 0 periodicities of 11 and 210 years also found in the solar modulated records of the cosmogenic isotopes 1obe and 14c suggest solar processes as the cause of these cycles depression of180 160 values cooling by volcanic eruptions is observed in stacked gisp215 80 records but the effect is small and not likely to trigger major climate changes

microbial lipid records of highly alkaline deposits and enhanced aridity associated with significant uplift of the tibetan plateau in the late miocene saline alkaline sediments and soils are widespread in arid and semiarid regions but their occurrence in ancient dry periods remains unknown due to the lack of a suitable proxy on the basis of investigations of modern chinese soils with a wide ph range of 3 5 9 1 we suggest that the microbial lipid ratio r i b i e the abundance ratio of archaeal isoprenoid gdgts glycerol dialkyl glycerol tetraethers to bacterial branched gdgts indicates the presence of drought induced alkaline deposits in terrestrial settings the r i b is invariant in modern soils with ph 600 mm but it increases sharply at higher ph values and lower mean annual precipitation i b ratio in a fluviolacustrine section in the zhada basin of the southwestern tibetan plateau covering the time period 9 2 2 6 m y ago the r i b ratio remains relatively stable in most intervals but exhibits maxima in some horizons indicative of the occurrence of severe drought and alkaline deposits in the basin catchment these occur in fluvial sediments deposited 9 m y ago a critical time with respect to the intensification of the east asian and indian monsoons and the significant uplift of the plateau that has previously been associated with enhanced aridity in central asia

paleoclimates and monsoon variations interpreted from micromorphogenic features of the baoji paleosols china abstract a full climatic interpretation of the loess paleosol sequence in china that covers the last 2 5 ma nearly continuously has been restricted because the soils in the oldest loess unit the wucheng loess spanning about 1 2 2 5 ma are not distinct enough to ensure accurate recognition and subdivision in the field recently the authors investigated the baoji loess paleosol sequence in the southern most part of the loess plateau where 37 paleosols were clearly defined including those of the wucheng loess based on macro and micromorphological observations the major pedogenic processes involved in the formation of the baoji paleosol are believed to be carbonate eluviation and illuviation clay translocation pseudogleization and rubification the diagnostic b horizons of the 37 soils are classified into four types bw or weak bt moderate bt strong bt and very strong bt the holocene soil at baoji contains a moderately developed bt which is interpreted to have formed under steppe forest vegetation most of the soils with bt horizons to the holocene soil are interpreted to be developed under forest and or steppe forest environments primary carbonates in most of the loess beds have been leached with the loess beds acquiring weak to strong granular structures the loess is subdivided into four types massive weakly weathered moderately weathered and strongly weathered they are believed to have mainly accumulated under steppe environments variations of monsoonal rain exhibit frequent and wide oscillations over the last 2 5 ma documented by alternations of loess and paleosol units the oscillatory pattern appears to be a function of the time interval considered

temperature changes reconstructed from branched gdgts on the central loess plateau during the past 130 5 ka abstract this study investigated the glycerol dialkyl glycerol tetraethers gdgts in a loess paleosol sequence lps to quantitatively reconstruct the mean annual air temperature mat on the central chinese loess plateau clp during the past 130 5 ka the results show that 1 mat variations reconstructed by global mbt methylation index of branched tetraethers and cbt cyclisation ratio of branched tetraethers transfer functions at xifeng range from 7 3 c to 28 4 c the mat variation on the central clp xifeng site is between the previously reported mat variations on the western yuanbao site and eastern clp mangshan site in agreement with the pattern that temperature increases from the northwestern clp to the southeastern clp 2 mat variations estimated by transfer functions of global mbt cbt global mbt cbt and chinese mbt cbt for lps are nearly all higher than the modern mat at xifeng indicating that the reconstructed mat values are probably overestimated 3 the maximum value of magnetic susceptibility at xifeng lagged that of the mat derived by mbt cbt proxy during the last interglacial 9 ka lag and since the last deglacial 6 ka lag

a high resolution absolute dated late pleistocene monsoon record from hulu cave china oxygen isotope records of five stalagmites from hulu cave near nanjing bear a remarkable resemblance to oxygen isotope records from greenland ice cores suggesting that east asian monsoon intensity changed in concert with greenland temperature between 11 000 and 75 000 years before the present yr b p between 11 000 and 30 000 yr b p the timing of changes in the monsoon as established with 230th dates generally agrees with the timing of temperature changes from the greenland ice sheet project two gisp2 core which supports gisp2 s chronology in this interval our record links north atlantic climate with the meridional transport of heat and moisture from the warmest part of the ocean where the summer east asian monsoon originates

chemical weathering in the krishna basin and western ghats of the deccan traps india rates of basalt weathering and their controls rates of chemical and silicate weathering of the deccan trap basalts india have been determined through major ion measurements in the headwaters of the krishna and the bhima rivers their tributaries and the west flowing streams of the western ghats all of which flow almost entirely through the deccan basalts samples n 63 for this study were collected from 23 rivers during two consecutive monsoon seasons of 2001 and 2002 the total dissolved solid tds in the samples range from 27 to 640 mg l 1 the rivers draining the western ghats that flow through patches of cation deficient lateritic soils have lower tds average 74 mg l 1 whereas the bhima except at origin and its tributaries that seem to receive na cl and so4 from saline soils and anthropogenic inputs have values in excess of 170 mg l 1 many of the rivers sampled are supersaturated with respect to calcite the chemical weathering rates cwr of selected basins which exclude rivers supersaturated in calcite and which have high cl and so4 are in range of 3 to 60 t km 2 y 1 this yields an area weighted average cwr of 16 t km 2 y 1 for the deccan traps this is a factor of 2 lower than that reported for the narmada tapti wainganga ntw systems draining the more northern regions of the deccan the difference can be because of i natural variations in cwr among the different basins of the deccan ii selection of river basin for cwr calculation in this study and iii possible contribution of major ions from sources in addition to basalts to rivers of the northern deccan traps silicate weathering rates swr in the selected basins calculated using dissolved mg as an index varies between 3 to 60 t km 2 y 1 nearly identical to their cwr the ca mg and na mg in these rivers after correcting for rain input are quite similar to those in average basalts of the region suggesting near congruent release of ca mg and na from basalts to rivers comparison of calculated and measured silicate ca in these rivers indicates that at most 30 of ca can be of nonsilicate origin a likely source being carbonates in basalts and sediments the chemical and silicate weathering rates of the west flowing rivers of the deccan are 4 times higher than the east flowing rivers this difference is due to the correspondingly higher rainfall and runoff in the western region and thus reemphasises the dominant role of runoff in regulating weathering rates the silicon weathering rate swr in the krishna basin is 15 t km 2 y 1 within a factor of 2 to those in the yamuna bhagirathi and alaknanda basins of the himalaya suggesting that under favourable conditions intense physical weathering high runoff granites and the other silicates in the himalaya weather at rates similar to those of deccan basalts the co2 consumption rate for the deccan is deduced to be 3 6 105 moles km 2 y 1 based on the swr the rate though is two to three times lower than reported for the ntw rivers system it still reinforces the earlier findings that in general basalts weather more rapidly than other silicates and that they significantly influence the atmospheric co2 budget on long term scales

distribution of glycerol dialkyl glycerol tetraethers in soils from two environmental transects in the usa abstract glycerol dialkyl glycerol tetraethers gdgts of both archaeal and bacterial origin form the basis of new temperature proxies applicable to soil and lake and marine sediments in soil branched gdgts are prevalent and their abundance of methyl or cyclic groups has been calibrated to mean annual temperature mat using mbt and cbt indices however soil ph is also known to be an important variable controlling the distribution of branched gdgts precipitation amount helps control soil moisture as well as ph and soil moisture is a leading variable affecting microbial diversity and activity in soil we have evaluated the distribution of gdgts from two soil transects in the usa a dry western transect covering six western states and a wet east coast transect from maine to georgia in order to assess the effect of precipitation on the distribution of soil gdgts our results show distinctly different gdgt distributions across climatic regions with dry western soils characterized predominantly by thaumarchaeotal isoprenoid iso gdgts and as a consequence low bit index values 0 2 0 6 and moist temperate east coast transect soils expressing mostly branched br gdgts and higher bit values 0 9 1 the predominance of iso gdgts in the western soils is related to the degree of aeration which in turn is related to precipitation amount and also to soil ph we also observed a substantial increase in the offset between measured mat and mbt cbt based mat below an annual precipitation of 700 800 mm yr 1 implying an impact of precipitation amount on mbt cbt based temperature reconstruction the data suggest that while soil tetraethers work well as a temperature proxy in moist temperate regimes they do not produce reliable measurements of temperature in sediments sourced from areas with 1 precipitation moreover erosion of soils with low bit values into lacustrine or marginal marine environments will not be detected via the bit index which can potentially affect paleotemperature reconstruction from sediments and so provide erroneous estimates of soil carbon delivery bit index values also show a correlation with precipitation amount the abundance of iso gdgts in western transect soils allowed calculation of tex 86 values but no correlation was found between tex 86 calculated temperature and mean annual temperature

tex86 as a potential proxy of lake water ph in the tibetan plateau abstract water ph represents one of the most important indicators of chemical and biological changes in lacustrine systems however although water ph is also a major influence on inland water bodies and related ecosystems it is not well studied in the lakes of the tibetan plateau tp the applicability of diatom assemblages an effective proxy of variations in water ph in freshwater lakes is greatly limited in the tp because the alkaline environment in most of the lakes is unfavorable for the preservation of diatom frustules isoprenoid glycerol dialkyl glycerol tetraethers igdgts are a series of specific membrane lipids biosynthesized by archaea which appear to be a promising method for reflecting lake water ph variations in this study we analyzed the distribution of igdgts in the surface sediments of 34 alpine tp lakes and combined the data with published igdgts results from across the tp in order to examine the effect of various environmental factors on igdgt cyclization the results show that water ph appears to be the most important factor affecting the degree of cyclization of igdgts in high elevation alkaline lakes this also suggests that the novel temperature proxy tex86 is also a promising water ph proxy for alpine lakes in the region despite a moderate correlation is observed between tex86 and water ph caution is needed in the interpretation of the tex86 records since other factors such as temperature and the dissolved oxygen level may also have an influence nevertheless tex86 appears to be a promising indicator of water ph for the alkaline lakes of the tp and it could be a potentially useful tool for reconstructing ph in alkaline lakes in other areas after regional calibrations

the coupled evolution of mid to late holocene temperature and moisture in the southeast qaidam basin abstract the southeast qaidam basin sqb lies near the boundary between the modern day asian summer monsoon asm and mid latitude westerly jet and the paleoclimate variation in this region can be affected by these two atmospheric circulation systems reconstructions of paleotemperature and palaeohydrology are therefore critical to constraining the driving forces of climate in this region where the ecological environment is fragile here we analyzed glycerol dialkyl glycerol tetraethers gdgts microbial membrane lipids occurring ubiquitously in aquatic and terrestrial environments across the globe in an aeolian sediment profile over the last 7000 years from xiangride town xrd of southeast qaidam basin sqb china the temperature record was generated using the global calibration of matmr based on branched gdgts brgdgts whereas the palaeohydrological condition was reconstructed from the relative abundance of isoprenoid gdgts vs brgdgts ri b the cyclisation index of brgdgts cbt and the brgdgt based ph indices the results show that the paleoclimate during the mid holocene was relatively warmer and wetter in the sqb afterwards it was a trend to a cold and dry climate temperature variation was highly coupled with the moisture change during the mid to late holocene as opposed to some previous studies showing a warm dry and cold wet climate pattern in the northern qaidam basin the palaeohydrological evolution agrees with the precipitation pattern of the chinese loess plateau but opposes to that in northeastern china the middle reaches of yangtze river and arid central asia aca implying that the asm strength is the driving force of precipitation evolution during the mid to late holocene in the sqb and the spatial heterogeneity of the mid to late holocene precipitation pattern across china is remarkable a rapid cold and drought event at around 4 ka before present bp was identified which might be a key factor that caused the decline in the agricultural civilization during the late neolithic age in northwestern china

the cretaceous tertiary boundary event in ecuador reduced biotic effects due to eastern boundary current setting a multidisciplinary study of a new cretaceous tertiary k t boundary section near guayaquil ecuador reveals an unusually cool water low diversity planktic foraminiferal fauna and a high diversity radiolarian fauna similar to those found in southern high latitude k t sequences despite the fact that this section was deposited near the cretaceous equator the k t boundary is located by planktic foraminifera within a narrow interval bounded by last appearances of tropical cretaceous species and first appearances of tertiary species including parvularugoglobigerina eugubina as in southern high latitudes there is no major mass extinction of either planktic foraminifera or radiolarians at this level a major radiolarian faunal discontinuity occurs some 6 m higher in the section within foraminiferal zone plc some 300 500 kyr after the k t event 13c values from bulk carbonates show both high and low latitude characteristics similarly to low latitudes there is a 3 negative 13c excursion at the k t boundary which is generally interpreted as a major decrease in primary productivity but unlike the low latitudes recovery occurs within a few thousand years as compared with 300 500 kyr and suggests rapid nutrient influx from the antarctic region via a current similar to the humboldt current today similarly to high latitude k t sequences a negative 13c shift occurs in the early danian zone plb about 300 kyr after the k t boundary sedimentologic and mineralogic data indicate a late maastrichtian with relatively low biogenic quartz and high carbonate followed by increasing biogenic quartz 50 and decreasing carbonate 5 during the early danian this suggests intensified atmospheric and oceanic circulation and upwelling off ecuador during the early danian the k t transition is marked by increased volcanic activity continental erosion and terrigenous influx but this also occurs in the early danian zone at the p1ap1b zonal transition and is thus not unique to the k t boundary we suggest that the catastrophic biotic effects normally observed at the k t boundary in low latitudes are greatly reduced or absent in the eastern equatorial pacific because this region was dominated then as now by upwelling and current transport of nutrient rich waters from the antarctic ocean as a result the biotic patterns are characteristic of southern high latitudes whereas the 13c pattern combines ameliorated low latitude effects with predominantly high latitude trends

molecular records of continental air temperature and monsoon precipitation variability in east asia spanning the past 130 000 years our current understanding of past changes in east asian summer monsoon easm precipitation intensity derives from several loess paleosol sequences and oxygen isotope 18o records of well dated stalagmites although temperature is generally presumed to have had minimal impact on easm records past air temperature dynamics over east asia are so far relatively poorly understood mainly due to the lack of tools to reconstruct continental paleotemperatures here we report a high resolution record of east asian air temperature over the past 130 000 years based on soil bacterial lipid signatures preserved in a loess paleosol sequence from the mangshan loess plateau in china we find that maximum local insolation is the main driver of air temperature although greenhouse gas concentrations and southern hemisphere climate may influence temperature at times when insolation is weak causing a decoupling with easm precipitation intensity direct comparison of our temperature record with precipitation induced changes in past soil ph derived from the same suite of lipids confirms this decoupling subsequent cross spectral analysis of the two molecular proxy records reveals that variations in monsoon precipitation consistently lag those in air temperature throughout the whole record at the dominant precession band the length of this lag is variable however and increases as glaciation develops this observation is consistent with an increasing influence of northern hemisphere ice sheets on the modulation of easm response to insolation forcing during ice ages

water geochemistry of the rivers around the taklimakan desert nw china crustal weathering and evaporation processes in arid land abstract major ion and sr2 concentrations and sr isotopic compositions of four major rivers in the tarim basin nw china were measured these rivers in the arid lands have high total cation concentrations tz ranging from 2 3 to 46 4 meq l 1 which are significantly higher than those of the global river average tz 0 725 meq l 1 ca2 mg2 and na in these rivers are the major cations together accounting for 95 of the total cations the total dissolved solids in the keriya and gaz rivers gradually increase from their upper to lower reaches these general features of these rivers show a strong effect of evaporation and the dissolution of the evaporates in the desert areas the chemical and isotopic compositions of these rivers are largely controlled by the geological signatures of their drainage areas the rivers at the northern foot of the kunlun mountains an old terrain show higher 87 sr 86 sr ratios of 0 7111 0 7154 compared to the aksu river 87 sr 86 sr 0 7103 0 7105 draining a relatively young area the end member identification by the intercorrelations between chemical and isotopic ratios shows three main sources which are derived from weathering of silicates carbonates and evaporates the yurongkash river keriya river and the small rivers flowing from the northern foot of the kunlun mountains have high total ion concentrations and are characterized by high na ca mg ca and k ca mole ratios 1 4 30 0 5 3 5 and 0 06 0 7 respectively showing a strong influence of soil salts on the other hand the aksu and gaz rivers draining regions in the western part of the tianshan mountains and kunlun mountains are dilute with respect to the amount of total dissolved solids and show low na ca mole ratio from 0 2 to 2 mg ca from 0 15 to 2 and k ca from 0 03 to 2 suggestive of a strong influence of carbonate weathering