the geochemical fingerprints of different tectonomagmatic environments using hygromagmatophile element abundances of tholeiitic basalts and basaltic andesites abstract using hygromagmatophile element abundances normalized to primordial mantle composition it is possible to discriminate between the tectonic settings of tholeiitic basalts and basaltic andesites 47 0 53 5 sio2 based on field and chemical evidence data from provinces or grouped localities have been compiled in order to establish chemical reference data sets for ocean island continental ocean ridge and floor subduction zone and back arc environments the disturbing effects of crustal contamination and hydrothermal alteration on the hygromagmatophile h element patterns are of minor significance in the recognition of plate tectonic settings on the basis of the data sets magmas from a number of ambiguous tectonic settings have been recognized using their h element patterns attention is directed to problems concerning rifting and drifting related basalts in an apparent continental setting and to the origin of ophiolite complexes using available data the pillow lavas of the troodos ophiolite complex cyprus are recognized as basalts erupted in a subduction zone environment

mid archaean evolution of the eastern indian craton geochemical and isotopic evidence from the bonai pluton abstract the archaean eastern indian craton consists of several granitoid batholiths intruding greenstone like sequences the bonai pluton one such body in the central sector of the craton consists of a dominant porphyritic and a subordinate equigranular variety ranging in composition from trondhjemite to granite xenoliths of massive trondhjemite migmatite and quartzite occur in both phases the granitoid xenoliths represent remnants of a sialic crust and are the oldest recognizable element in the bonai pluton these are high al 2 o 3 trondhjemites with a highly fractionated rare earth element ree pattern a pb pb isochron age of 3369 57 ma has been obtained from a few spatially related xenoliths the porphyritic and equigranular granitoids show similar petrographic characteristics and most of the samples show a calc alkaline trondhjemitic association a few granite samples however belong to a normal calc alkaline association the trondhjemitic samples are of the low al 2 o 3 type with fractionated light ree lree flat heavy ree hree and a marked negative eu anomaly granites of the calc alkaline association have an identical ree pattern pb isotopic data for all samples together yield a pb pb isochron age of 3163 126 ma the ree characteristics of the two trondhjemite suites can be generated by partial melting of a mafic source with variable residual phases at different depths on the other hand the normal calc alkaline granite may be generated by partial melting of trondhjemite similar in composition to that represented by the 3369 ma xenoliths isotopic ages and the chemical nature of the bonai pluton are similar to those identified in the adjacent singhbhum granite complex it is suggested that the entire eastern indian craton has a common mid archaean history the earliest sialic crust formed at 3400 ma and was followed by trondhjemitic addition at 3300 ma during this phase restricted reworking of the older sialic crust produced calc alkaline granites

the karoo igneous province a problem area for inferring tectonic setting from basalt geochemistry tholeiitic basalts and associated intrusives are the major component of the karoo igneous province they are of mesozoic age and constitute one of the world s classic continental flood basalt cfb provinces it has been argued that most karoo basalts have not undergone significant contamination with continental crust and that their lithospheric mantle source areas were enriched in incompatible minor and trace elements during the proterozoic the only exceptions to this are late stage morb like dolerites near the present day continental margins which are considered to be of asthenospheric origin when data for the southern karoo basalts are plotted on many of the geochemical discriminant diagrams which have been used to infer tectonic setting essentially all of them would be classified as calc alkali basalts cab s or low k tholeiites virtually none of them plot in the compositional fields designated as characteristic of within plate basalts there is little likelihood that the compositions of the karoo basalts can be controlled by active subduction at the time of their eruption and no convincing evidence that a subduction component has been added to the subcontinental lithospheric mantle under the entire area in which the basalts crop out it must be concluded that the mantle source areas for cab s and the southern karoo basalts have marked similarities in contrast the data for northern karoo basalts largely plot in the within plate field on geochemical discriminant diagrams available data suggest that the source composition and or the restite mineralogy and degree of partial melting are different for southern and northern karoo basalts there is no evidence for any difference in tectonic setting between the southern and northern karoo basalts at the time they were erupted this appears to be clear evidence that specific mantle source characteristics and or magmatic processes can vary within a single cfb province to an extent that renders at least some geochemical discriminant diagrams most unreliable for classifying tectonic environment with respect to continental volcanic rocks

sulfur isotopes and hydrochemical variations in spring waters of southern indiana u s a abstract water chemistry and 34 s so 4 studies suggest two flow systems in the karst terrane of southern indiana 1 a shallow flow system exists which is dominated by surface water entering the ground through fractures and 2 a deeper regional groundwater flow system recharged by diffuse flow the chemistry of the water in the regional system may be dominated by the solution of gypsum in the lower st louis limestone sulfur isotope studies suggest two flow systems and show that the high so 2 4 concentrations in local waters result from solution of gypsum reported 34 s so 4 for upper mississippian evaporites and fresh water range from 14 to 19 to 8 to 12 respectively isotope analysis of gypsum cores from the lower st louis limestone evaporite unit shows 34 s values between 14 10 and 15 13 in the study area groundwater chemistry studies show a direct linear relationship between so 2 4 concentrations and 34 s values groundwater varies in so 2 4 concentrations between 20 and 1970 mg l 1 the 34 s values range from 10 61 for a conduit spring to 18 57 for a diffuse spring the waters with high so 2 4 concentrations have 34 s so 4 values higher than the local gypsum deposits analysed and contain h 2 s suggesting a deeper flow system in which fractionation by bacterial reduction of so 2 4 is occurring waters with low so 2 4 concentrations have 34 s so 4 values in the range of local fresh water indicating a shallow flow system

the composition and evolution of the continental crust rare earth element evidence from sedimentary rocks the composition of the present day upper crust inferred from the uniformity of sedimentary rock r e e rare earth element patterns is close to that of granodiorite a revised andesite model is used to obtain total crustal composition the lower crust is the composition remaining assuming that the upper crust one third of the total is derived from intracrustal partial melting the upper crustal r e e pattern has pronounced eu depletion eu eu 0 64 the lower crustal pattern has eu enrichment eu eu 1 17 and the total crust has no eu anomaly relative to chondritic abundances the eu depletion in the upper crust is attributed to retention of eu in plagioclase in the lower crust because plagioclase is not stable below 40 km 10 kbar the anomaly is intracrustal in origin the archaean upper crust has a different r e e pattern to that of the present day upper crust being lower in total r e e and la yb ratios and lacking an eu anomaly these data are used to infer the archaean upper crustal composition which resembles that of the present day total crust except that ni and cr contents are higher the archaean crustal composition can be modelled by a mixture of tholeiites and tonalite trondhjemites the latter have steep light r e e enriched heavy r e e depleted patterns consistent with equilibration with garnet and hence probable mantle derivation there is little reason to suppose that the archaean lower crust was different in composition from the upper crust except locally where partial melting episodes occurred the r e e evidence is consistent with isotopic and geological evidence for a low continental growth rate in the early archaean a massive increase to about 70 of the total crust between about 3000 and 2500 ma b p and a slow increase until the present day the change from archaean to post archaean r e e patterns in the upper crust is not isochronous but is reflected in the sedimentary rock r e e patterns at differing times in different continents on the basis of a model composition for the mantle 36 of the potassium 30 of uranium 15 of lanthanum and 3 of ytterbium are concentrated in the present continental crust this enrichment is related to ionic size and valency differences from common mantle cations e g mg fe pre 3 9 ga b p crusts were obliterated by meteorite bombardment no geochemical evidence exists for primordial anorthositic sialic or mafic crusts

geochemical evidence for the volcanic arc tectonic setting of the dhanjori volcanics singhbhum craton eastern india geochemical data on the dhanjori volcanics of the singhbhum craton indicate that they range from basalt to andesite and show an iron enrichment trend various chemical characteristics suggest that they are differentiated along the trend similar to that of orogenic suites and have a strong affinity with island arc tholeiites the field relationships as well as other geological information also support this conclusion and indicate their eruption on a thin continental margin it is inferred that the dhanjori volcanics were probably erupted as a result of plate convergence in northern singhbhum with subduction of oceanic crust below the singhbhum craton

precambrian mafic dyke swarms in the singhbhum craton eastern india and their links with dyke swarms of the eastern dharwar craton southern india discussion

dating the oldest terrestrial rocks fact and fiction abstract this paper is a review of well documented geochronological and related isotopic evidence for the age and total crustal residence time of the oldest known terrestrial rocks mainly using rb 1bsr sm 1bnd and u 1bpb decay schemes the oldest known stable sialic crust of true continental character predominantly composed of calc alkaline orthogneisses was produced during major mantle differentiation some 3 7 3 5 ga ago and is represented on several continents enclaves of older supracrustal rocks as well as a major remnant of a volcano sedimentary sequence of greenstone belt affinity dated at 3 8 ga are preserved within the surrounding gneisses in southern west greenland recent ionmicroprobe evidence for 4 1 ga old detrital zircon grains in a younger early archaean metasedimentary sequence in western australia is also discussed several cases are reviewed where claims for early archaean 3 4 ga dates are believed to be erroneous and to result from oversimplistic and incorrect interpretation of isotopic data some of the geological and geochemical mechanisms which have given rise to claims for spuriously old sm 1bnd u 1bpb and pb pb dates are critically discussed to supplement published data we present several new sets of whole rock sm 1bnd and pb pb isotopic data from west greenland labrador zimbabwe and eastern india relevant to the overall topic of this review

evidence for melt lubrication during large earthquakes 1 rotary friction experiments have been performed on westerly granite at start velocities of 2 0 4 0 m s 1 under loads of 250 500 n until the system stalls up to 4 s interface temperature velocity and force were measured at intervals of 0 2 milliseconds the results show that kinetic friction increases in direct proportion to temperature up to a critical value tcr whereupon the system changes from boundary lubrication slip strengthening to hydrodynamic lubrication slip weakening with an associated decrease in friction and temperature for westerly granite tcr is 1150 c this corresponds to the melting point of feldspar which constitutes 50 of the rock if tcr is exceeded in natural slip systems which will depend on rock type this can result in the generation of friction melt melt lubrication can explain the scaled energy of large earthquakes being 10 to 100 times more than that of small earthquakes

variations of chemical features in a monsoon glacier watershed southeastern tibet plateau the ph ec electric conductivity 18o and major ions in melt water precipitation runoff and groundwater samples which were collected in baishui basin were analyzed based on chemical analysis the characteristic variations are analyzed in this paper the melt water precipitation runoff and groundwater were ca2 mg2 hco3 type with similar ion compositions but showed different ion concentrations normally the content is high in groundwater and runoff water but low in melt water and precipitation from the upper basin glacier downward there was a general increasing trend for the total ion concentrations in basin hco3 and ca2 accounted for more than 80 of total ions in samples indicating that ions mainly came from limestone and water typical of carbonate solution water water rock interaction is the significant contributor to water geochemistry the concentration of inorganic ion in melt water had an obvious diurnal variation with temperature change the 18o values increases with the altitude decrease the similarity of 18o in runoff and groundwater samples was due to their frequent transformation in karst regions

comparative study of streamflow components in two inland rivers in the tianshan mountains northwest china runoff generation and its dynamics are fundamental to hydrology and very crucial to water resource management based on isotope hydrograph method we explored and compared the runoff generation mechanism of two typical inland rivers in the tianshan mountains i e urumqi river on the north slope and huangshuigou river on the south slope based on a year long frequently monitored weather flow and isotope data results show the following 1 in both rivers precipitation river water and groundwater exhibit noticeable spatial and temporal variations in stable 18o and d compositions in the urumqi river and huangshuigou river and there is an increasing trend of 18o in the river water during snowmelt period 2 isotope hydrograph separation shows that generally groundwater is the major recharging source over 50 of streamflow followed by glacier melt snowmelt and precipitation in these two rivers and urumqi river has a larger contribution from glacier melt than huangshuigou river 3 these two rivers have similar contribution components in all seasons except spring in which huangshuigou river has similar contributions from groundwater 55 6 and snowmelt 44 4 whereas urumqi river has a larger contribution from groundwater 72 7 than snowmelt 27 3 4 the urumqi river is more sensitive to the temperature change than the huangshuigou river which might cause flooding that resulted from glacier melt in the urumqi river

chemical and isotopic evidence for hydrogeochemical processes occurring in the lincolnshire limestone over 150 groundwater samples from the lincolnshire limestone have been analysed for ph major ions and 13c ratios where possible field eh and iodide concentrations were measured and methane concentrations were determined for 12 samples stable isotope ratios were determined for soil and rock carbonate samples a system of zonation allows the division of hydrogeochemical processes occurring in the aquifer the use of hydrochemical and isotope data in modelling exercises enables the re evaluation and possible enhancement of the understanding of hydrogeochemical processes the carbonate chemistry of outcrop groundwaters is explained by calcite saturation being achieved under open system conditions in the soil zone 13c ratios in the range 15 99 to 10 57 may be generated from a stoichiometric reaction with possible additional partial and or simultaneous exchange with soil co2 or carbonate the isotopic composition of soil carbonate shows the effects of precipitation from soil waters the incongruent dissolution of primary depositional limestone carbonate results in increasing magnesium and strontium concentrations and increasing 13c ratios for the groundwaters with flow down the hydraulic gradient as a result of incongruent dissolution secondary calcite may be precipitated onto fissure surfaces significant nitrate and sulphate reduction in non saline groundwaters is not supported by the results of hydrochemical and isotope modelling exercises however sulphate reduction and methane fermentation may be affecting the isotopic and chemical compositions of saline groundwaters sodium calcium ion exchange leads to limited calcite dissolution deep in the aquifer but the evolution of these groundwaters is confused by the uncertain effects of oxidation of organic carbon and mixing with a saline end member solution

soluble ionic and oxygen isotopic compositions of a shallow firn profile baishui glacier no 1 southeastern tibetan plateau in the summer of 2004 a firn profile 18 3m long extending down to glacier ice was recovered in the accumulation area of the largest glacier baishui no 1 on yulong mountain the southernmost glacier covered area in mainland eurasia multivariate empirical orthogonal function eof and statistical correlation analyses of major ion data from the profile demonstrate that three distinct types of ionic material contribute to the chemical characteristics of firn in this monsoonal region material of marine origin which is transported by the indian southwest monsoon crustal materials which come from local sources and anthropogenic pollutants which are produced by industrial and agricultural activities in south asia although the influence of post depositional processes on the seasonal isotopic and soluble ionic compositions is significant dust layers in the firn profile are clearly visible due to the effects of meltwater percolation the dust layers generally coincide with latesummer snow surfaces we therefore use the dust layers combined with the seasonal variations of electrical conductivity ec ca and mg to establish a depth age scale for the firn profile the reconstructed net accumulation has a significant negative correlation with the temperature at lijiang whereas the correlation between the net accumulation and the precipitation amount at lijiang is weak although the do time series of the firn profile was modified significantly by meltwater percolation the correlation between annual mean do values and the indian southwest monsoon index wsi1 is significant this result suggests that do records from monsoon influenced temperate glaciers can provide a valuable record of past variations of the indian southwest monsoon

the impact of glaciers on the runoff and the reconstruction of mass balance history from hydrological data in the tropical cordillera blanca peru a 41 years series of runoff and precipitation data from the peruvian cordillera blanca demonstrates the high hygric seasonality in this tropical high mountain range in this area glaciers have a crucial impact on runoff which is of essential importance for the highly populated and cultivated valley of the callejon de huaylas particularly during the dry season whereas the mid latitudes glacier runoff amplifies the seasonal variation of runoff the effect of glaciers in the low latitudes is a smoothing one it decreases clearly with the decreasing degree of glaciation in addition particular circumstances of this tropical environment allow the reconstruction of a glacier mass balance history from the hydrological data for the second half of the 20th century it shows a high synchronicity with the global trend of periods with glacier mass loss and gain comparison with length variations of three individual glaciers indicate a rather fast reaction of these glaciers to changes in mass balance although the mass balance variations show some differences among the individual catchment basins the over all trend is uniform a general positive correlation of mass balance variations with soi is obvious but not regular

non recognition of continental tholeiites using the ti y zr diagram continental tholeiites cannot be identified using the ti y zr diagram two hundred and thirteen analyses from 16 localities representing 7 continental tholeiitic provinces all plot outside the within plate basalt field of this diagram

geochemistry and petrogenesis of amphibolites kolar schist belt south india evidence for komatiitic magma derived by low percentages of melting of the mantle the kolar schist belt of the dharwar craton of south india is an archean greenstone belt dominated by metavolcanic rocks the mafic metavolcanic rocks occur as komatiitic and tholeiitic amphibolites the komatiitic amphibolites occur along the margins of the n s trending synformal belt they are much less abundant than the tholeiitic amphibolites and have 14 to 21 3 wt per cent mgo the komatiitic amphibolites from the west central part of the belt have two distinctive ree patterns 1 those enriched in the middle to light ree but depleted in ce relative to nd and 2 those with patterns that are convex up i e depleted in both light and heavy ree although more depleted in the light ree associated tholeiites have light ree depleted to flat ree patterns komatiitic and tholeiitic amphibolites from the eastern part of the belt have enriched light ree patterns the tholeiitic amphibolites from the kolar schist belt are similar to the th i and th ii types of archean tholeiites of condie 1981 the komatiitic amphibolites are similar to komatiites and komatiitic basalts of barberton mountainland but have higher feo and tio 2 abundances and lower yb gd ratios the petrogenetic interpretations for these rocks are based primarily on a modification of the mgo feo diagram of hanson langmuir 1978 and modelling of zr ni and ree all of the rocks have undergone some fractionation while the modelling does not give accurate temperatures pressures compositions and extents of melting of the mantle sources for the various amphibolites it does present an approach which can be used for estimating these parameters for example the komatiitic amphibolites appear to be derived from melts generated by 10 to 25 per cent melting of the mantle over a range of depths and temperatures greater than 80 km and 1575 c the variation in the p t conditions of magma generation is possibly due to adiabatic melting in mantle diapirs with a range of feo mgo ratios if the tholeiitic amphibolites are derived from similar mantle sources it is not clear that they are their parent melts may have been generated by similar extents of melting but at depths of less than 80 km the komatiitic amphibolites from the west central part of the belt were generated from light ree depleted mantle whereas those from the eastern part of the belt appear to have been generated from light ree enriched mantle the sources for the komatiitic amphibolites in both areas were significantly enriched in feo relative to pyrolite thus a light ree depleted and a light ree enriched source appear to have provided mafic volcanics with similar major element chemistry to this belt during its evolution

mesoarchaean palaeoproterozoic stratigraphic record of the singhbhum crustal province eastern india a synthesis the mesoarchaean palaeoproterozoic stratigraphic record of the singhbhum crustal province eastern india implies sedimentation and volcanism in a changing tectonic scenario and thus assumes immense geological significance although efforts have been made by many researchers in the past several decades to summarize various geological aspects of the singhbhum crustal province a critical synthesis of various stratigraphic issues was long overdue the present contribution is an updated critical synthesis of the mesoarchaean palaeoproterozoic stratigraphic record of the singhbhum crustal province we have pointed out the problematic stratigraphic issues of the singhbhum crustal province that deserve careful scrutiny in order to gain better insights into the mode of stratigraphic sequence building

proterozoic sedimentation and volcanism in the singhbhum crustal province india and their implications abstract the proterozoic volcano sedimentary succession comprising successively younger dhanjori chaibasa dhalbhum dalma and chandil formations of the singhbhum crustal province india records sedimentation and volcanism in a rapidly changing tectonic scenario cooling of the vast volume of archaean singhbhum granite possibly induced an isostatic readjustment the associated tensional regime and deep seated fractures controlled the formation of the proterozoic singhbhum basin the dhanjori formation unconformably overlies the singhbhum granite and is entirely terrestrial dominantly fluvial at the base the conglomerate deposits coarse grained sandstone and shale represent the distal fringe of an alluvial fan complex the rest of the formation including the volcaniclastic rocks consists almost entirely of fining upward fluvial cycles the base of the dhanjori formation is a sequence boundary and the formation itself represents a lowstand systems tract the dhanjori volcano sedimentary succession displays evidence of having passed through passive as well as active phases of continental rifting with an increasingly important influence of volcanism on the sedimentation through time the chaibasa formation sharply overlies the dhanjori formation and a transgressive lag demarcates their contact the basal part of the chaibasa formation immediately overlying the transgressive lag deposit represents a transgressive systems tract while offshore shales that sharply overlie the shallow marine sandstones up section represent marine flooding surfaces the shallow marine subtidal sandstones bear an excellent record of sandwave migration and provide a rare opportunity to unlock the late palaeoproterozoic lunar orbital periodicities unlike the chaibasa the overlying dhalbhum formation is entirely terrestrial fluvial aeolian indicating that the chaibasa dhalbhum contact is a sequence boundary the dalmas overlying the dhalbhum formation represents concordant lava outpourings without any break in sedimentation these lavas are genetically related to mantle plume upwelling in an intracontinental rift setting the volcano sedimentary package lying north of the dalma volcanic belt chandil formation is of mesoproterozoic age the entire late palaeoproterozoic volcano sedimentary package displays post depositional compressional deformation and greenschist to amphibolite facies metamorphism dated at ca 1600 ma forming the so called north singhbhum fold belt the volcano sedimentary package lying south of the dalma volcanic belt was pushed further south towards the singhbhum granite batholith complex as a result of uplift related to the dalma plume the singhbhum granite batholith acted as a rigid body this gave rise to a compressional stress regime that induced shearing thrusting at ca 1600 ma along the singhbhum shear zone the dalma plume magmatism was possibly part of a 1600 ma global tectono thermal event

selective melting processes as inferred from experimentally generated pseudotachylytes abstract high speed friction experiments have been conducted on gabbros and granites to better constrain the process of frictional melting during seismogenic fault motion experiments were done on cylindrical specimens of 25 mm in diameter under a normal stress of 1 0 1 5 mpa and at slip rates up to 2 m s using a rotary shear high speed frictional testing machine the experimentally generated pseudotachylytes consist of a fused glassy matrix with abundant vesicles and angular or sub angular to rounded fragments these locally occur as injected network veins in the fractured rock x ray diffraction analysis has revealed the presence of as much as 40 70 wt glass the mineral contents of clasts in the experimental pseudotachylyte in granite as determined by x ray diffraction analysis indicate that quartz is the most resistant to melting biotite the least and feldspar is intermediate thus the sio2 depletion in natural pseudotachylyte glass is likely to be due to the selective melting of constituent materials during frictional melting

gravity field over singhbhum its relationship to geology and tectonic history abstract the gravity field over singhbhum and adjoining areas lying between latitude 21 to 23 15 n and longitude 84 to 87 30 e has been analysed the region has a very complex precambrian history dating as far back as 3200 m y and extending up to 850 m y during which time it experienced a number of orogenic cycles the activity has left an imprint on the gravity field which is marked by prominent gravity highs and lows the highs are invariably surrounding the singhbhum granite batholith whereas the lows are conspicuous over the granites and their margins the regional gravity field has been removed using a 4th order polynomial surface the residual anomalies over prominent highs and lows have been interpreted using two dimensional and three dimensional models for underlying rock formations it is inferred that the gravity highs are generally related to synclinal structures filled with sedimentary or metasedimentary formations and volcanics such as the iron ore group the singhbhum group dhanjori and simlipal basins the gravity lows can be attributed to a considerable thickness of granites of varying density which could have been formed during different metamorphic orogenic cycles by melting of a preexisting sialic crust

evolutions of water stable isotopes and the contributions of cryosphere to the alpine river on the tibetan plateau the significant changes of cryosphere on the tibetan plateau tp are an important cause of concern for the huge population in asia which depends on the glacier permafrost feed rivers up to now little is known about the response of runoff to the cryospheric changes under a warming climate taking an example of a typical alpine river hereafter named klr river in kunlun mountains pass on the tp to investigate the hydrological processes and quantify the potential recharge sources using stable isotopes and electrical conductivities the results showed significantly temporal variations in isotopes of precipitation and river water deviations in the precipitation isotopes indicated that precipitation in kunlun mountains pass during summer months mainly originated from local recycled moisture and slightly influenced by monsoon the klr river was separated into three hydrological components which include precipitation meltwater of glacier and meltwater of subsurface ground ice on average the meltwater of glacier accounted for 56 64 of total flow whereas the meltwater of subsurface ground ice contributed 37 44 and only 5 92 was supplied by precipitation evidently the contributions of glacier and thawing permafrost are up to as high as 94 the cryosphere played a crucial role on the hydrological cycle on the tp which would be important to understand the water resource distribution in permafrost regions on the tp under the global warming

the significance of source versus process in the tectonic controls of magma genesis arculus r j 1987 the significance of source versus process in the tectonic controls of magma genesis in s d weaver and r w johnson editors tectonic controls on magma chemistry j volcanol geotherm res 32 1 12 despite the association of certain characteristic trace element signatures with particular tectonic environments of eruption there are accumulating data which would result in significant tectonic misassignments ambiguity of signals appears in active arc back arc systems of the southwestern pacific and particularly in some intracontinental plate suites given the selective preservation of continental as opposed to oceanic lithosphere inappropriate paleotectonic inferences are probable using trace element criteria alone strong relative fractionation of the alkalis and alkaline earth elements aee with respect to the rare earth elements ree in the majority of arc related magmas and a number of intraplate continental basalts is strongly suggestive of the involvement of hydrous fluids at some stages in the respective petrogenetic processes occurring in these two tectonic regimes in contrast fractionation of high field strength elements hfse such as nb and ta with respect to the ree in the same suites is most readily explained by the involvement at some stage in the magma formation process of high sio2 melts a number of widely applied tectonic discriminants makes use of aee hfse fractionation but the processes and sources involved in subduction zone petrogenesis may be duplicated during interaction of mantle derived basalt with the heterogeneous components of continental lithosphere both mantle and crust a significant role for both volatile dominated fluids and silicate melts is implicated in collision and some intracontinental plate magmatism

environmental significance and hydrochemical processes at a cold alpine basin in the qilian mountains isotope geochemistry of precipitation river water well water and spring water in the babao river basin china during different seasons showed that regional runoff was dominated by precipitation in summer and autumn and by underground water in winter and spring the 18o and d values of precipitation and spring water displayed a clear altitude effect water from the main stream and tributaries displayed a converse altitude effect in the summer wet season the isotopic composition of the various water sources was not well correlated with elevation during the winter dry season the spatial distribution of the stable isotope signals of river water demonstrated the influence of rainfall inputs evaporation and variable flow an end member mixing model used for hydrograph separation indicated that in the summer wet season the babao river water was recharged by precipitation 71 9 spring water 11 7 and well water 16 4 whereas the winter dry season recharge was sourced from spring water 28 2 and well water 71 8

early proterozoic metallogeny tectonics and geochronology of the singhbhum cuu belt eastern india abstract the singhbhum thrust belt hosts three types of mineralisation sulphides of copper and other metals uranium oxides and apatite magnetite regional geological investigations reveal that the thrust belt and the mineralisations evolved through several distinct geological episodes 1 the oldest is the deposition of the protoliths of the older metamorphic group their subsequent deformation and metamorphism and the post kinematic intrusion of the singhbhum granite the older metamorphic orogeny 3 15 3 0 ga the chotanagpur gneiss to the north is also thought to have originally belonged to this period 2 the chotanagpur gneiss and the singhbhum granite together formed an extensive sialic basement of the archaean period which subsequently underwent extension producing a continental basin filled with platform sediments of the iron ore group and deep sea basins on sialic basements filled with flysch like sediments of the singhbhum group this was accompanied by extensive mafic volcanism the dalma volcanics the dhanjori volcanics and the dolerite dyke the sulphide ores were formed as strata bound layers associated with the volcanism of the dhanjori volcanics uranium minerals and phosphates were deposited as sediments or related to later felsic plutonic activity volcanism sedimentation and mineralisation were controlled by rift fractures forming the basins these were later subjected to deformation and metamorphism of the singhbhum orogeny 2 05 2 0 ga the rift fractures developed into thrust belts felsic magmatic activity took place hydrothermal activity along the thrust belt modified the mineralised belt 3 a later thermal event 1 6 ga was imprinted on the rocks of the thrust belt

hydrograph separation using isotopic chemical and hydrological approaches strengbach catchment france the streamflow components were determined in a small catchment located in eastern france for a 40 mm rain event using isotopic and chemical tracing with particular focus on the spatial and temporal variations of catchment sources precipitation soil solution springwater and streamwaters were sampled and analysed for stable water isotopes 18o and 2h major chemical parameters so42 no3 cl na k ca2 mg2 nh4 h h4sio4 alkalinity and conductivity dissolved organic carbon doc and trace elements al rb sr ba pb and u 18o si doc ba and u were finally selected to assess the different contributing sources using mass balance equations and end member mixing diagrams isotopic hydrograph separation shows that the pre event water only contributes to 2 at the beginning of the stormflow to 13 at the main peak flow doc associated to si and u to ba allow to identify the different contributing areas upper layers of the saturated areas deep layers of the hillslope and rainwater the streamflow 70 originates from the deep layers of the hillslope the remaining being supplied by the small saturated areas the combination of chemical both trace and major elements and isotopic tracers allows to identify the origin of water pathways during the first stage of the storm event a significant part of the runoff 30 39 comes from the small extended saturated areas located down part of the basin overland runoff then groundwater ridging during the second stage the contribution of waters from the deep layers of the hillslope in the upper subcatchment becomes more significant the final state is characterised by a balanced contribution between aquifers located in moraine and downslopes indeed this study demonstrates the interest of combining a variety of hydrometric data geochemical and isotopic tracers to identify the components of the streamwater in such conditions

stable isotope geochemistry of sulfate in relation to hydrogeology in southern saskatchewan canada abstract isotope and chemical analyses were carried out on soil and water samples collected from testholes drilled into different stratigraphic layers at six locations in the assiniboia area southern saskatchewan to understand the origin and distribution of so 4 and sources of groundwater recharge the 34 s so 4 and 18 o so 4 values were mostly negative indicating oxidation of highly reduced sulfide in subsurface environments as the major source of so 4 in the soils and groundwaters however positive or near positive 34 s and 18 o values in some of the samples indicated that oxidation of sulfide with positive or near positive 34 s values or dissolution of a so 4 mineral such as evaporite gypsum may serve as alternate sources of s salt concentration and isotope compositions in the eastend sand were nearly uniform in comparison with till and shale layers total s content in the sediments varied from 0 7 to 3 2 g kg with greater accumulations in the till layer which were mostly 1 0 g kg the insoluble s fraction of the sediments was 4 s was the major form of s the 34 s and 18 o values of soluble so 4 and 18 o and d values of groundwaters provide supporting evidence of groundwater flow direction determined by other techniques the d and 18 o values of the groundwater samples varied between 131 and 119 and 15 2 to 11 4 respectively without any correlation with stratigraphy these data plot on a d vs 18 o line with a slope of 2 0 this departure from the meteoric water line with slope of 8 0 appears to be the result of evaporation or oxygen exchange with soil minerals the o isotope data suggest that exchange between so 4 and h 2 o is very slow under the conditions prevailing in the subsurface

spatial and temporal variations of oxygen isotopes in snowpacks and glacial runoff in different types of glacial area in western china in order to improve understanding of spatial and temporal variations of stable isotopes in atmospheric precipitation snow cover and glacier meltwater in different regions of china samples were collected for isotopic analysis in four areas yulong mountain yunnan himalaya temperate glacier area samdain kangsang mountain nyainqentanglha shan subpolar glacier area the headwater area of the urumqi river tien shan subpolar glacier area and muztag mountain pamirs polar glacier area sampling was undertaken in both summer and winter between 2000 and 2003 the d 18 o values show a temperature altitude effect in new winter snow on yulong mountain reflecting the condensation and fractionation processes associated with the winter monsoon but a different more complex pattern in residual snow deposited during the summer monsoon this old snow is influenced by the precipitation amount effect solar radiation and evaporation and the water content of the snowpack the summer precipitation at samdain kangsang mountain is associated with the summer monsoon there is a marked precipitation amount effect during the long passage of the southwest india monsoon from the distant moisture source to samdain kangsang mountain and the summer precipitation is strongly depleted of the heavy isotope above 6000 m the high radiation flux causes much evaporation from the snow surface the associated 18 o enrichment of the snow is reflected in a reverse altitude effect the d 18 o values in the summer snowpack of the tien shan and muztag mountain decrease with increasing altitude and decreasing air temperature indicating a temperature altitude effect post depositional processes cause isotopic changes during the transformation of snow firn ice to meltwater the effects are much stronger at temperate than at polar glaciers moreover changes in the isotopic signal at both temperate and polar glaciers can result from evaporation sublimation ablation and drifting

sulfate in brines in the crystalline rocks of the canadian shield abstract deep groundwaters in crystalline rocks typically are very saline and are characterized by a rather unique ca na cl dominated chemistry sulfate is present in variable amounts and may be linked to both the geochemical evolution of these fluids as well as to recent processes initiated through mining activities it is possible to distinguish on the basis of isotopic compositions between brine sulfate and secondary sulfate formed by oxidation of sulfides the latter is characterized by 34 s values which reflect the local mineral sulfide precursor and 18 o close to or below 0 smow the isotopic composition of the brine sulfate is characterized by 18 o and 34 s values which resemble marine isotopic compositions at some localities at others they could be explained as being of magmatic hydrothermal origin it is likely that the sulfate participated in the geochemical evolution of these brines thus its isotopic composition reflects geochemical processes rather than a primary origin no evidence for the influence of bacterial reduction was found

basalt geochemistry and tectonic discrimination within continental flood basalt provinces abstract continental flood basalts are usually regarded as a single tectonomagmatic entity but frequently quoted examples exhibit a variety of tectonic settings in one well studied classic flood basalt province the mesozoic karoo province of southern africa magmatism occurred in the following tectonic settings a continental rifting leading to ocean floor spreading in the south atlantic ocean etendeka suite of namibia b stretched continental lithosphere and rifting not leading directly to ocean floor formation lebombo suite of southeastern africa and c an a tectonic within plate continental setting characterized by an absence of faulting or warping lesotho highlands and karoo dolerites of south africa by means of spidergrams of the elements rb ba th nb k la ce sr nd p hf zr sm ti tb y v ni and cr uncontaminated tholeiites from c above i e the lesotho type continental flood basalts ltcfb are compared with mid ocean ridge basalts morb ocean island tholeiites oit and tholeiites and calc alkali basalts from subduction environments the comparison reveals the ltcfbs are geochemically distinct the differences are reflected in relative enrichments or depletions of the more incompatible elements rb ce to less incompatible elements ce y i e the overall slope of the spidergrams and in anomalous enrichments or depletions of one or more of the elements th k nb sr ti hf and zr the distinctive geochemical character of the lesotho ltcfbs is interpreted in terms of a lithospheric mantle source for the basalts this is supported by isotopic data there are no major geochemical differences between lesotho cfbs and basalts of the rift related etendeka and lebombo suites although the latter are somewhat enriched in rb ba and k however unlike the lesotho basalts the lebombo and etendeka basalts are associated with voluminous silicic volcanics or intrusive centres and late stage dolerites having morb oit i e asthenospheric geochemical characteristics the flood basalt silicic magmatism late stage dyke swarm association is characteristic of several rift or thinned lithosphere environments e g ethiopia skye eastern greenland but in many of these the flood basalts have ocean island basalt oit geochemical characteristics the lesotho type cfb geochemistry is exhibited by the grande ronde basalt of the columbia river group a possible subduction related flood basalt province and the basic rocks associated with mesozoic rifting in the north and south atlantic basalt geochemistry alone is unhelpful in determining the tectonic setting of cfbs although the rift related environments may be identified by the petrology and geochemistry of the whole igneous suite a two source model is proposed for the mantle derived basic rocks in rift related cfb provinces early enriched basalts are derived from the lithosphere and following pronounced lithospheric attenuation or rifting later morb like melts are emplaced from the rising asthenosphere the presence of both lesotho and oit type geochemical patterns in rift related cfbs suggests that the lithosphere exhibits different styles of enrichment

precambrian tectonic evolution of eastern india a model of converging microplates the precambrian formations of the singhbhum and chotanagpur region of the indian peninsular shield are tectonically classified and their implications in the context of plate tectonics are reviewed on the basis of the stratigraphic structural petrologic geochemical geophysical and geochronologic data that have accumulated through extensive research in the region in recent years it is shown that the essential elements in tectonic settings geological facies and structural and metamorphic characters of the singhbhum orogenic belt and the reactivated chotanagpur plateau are elegantly interpretable in terms of interaction of two converging microplates named here as the singhbhum and chotanagpur plates a detailed correlation of the tectonic evolution with the different stages of a proposed model of plate motions is attempted in the paper the study reveals three cycles of plate motions with intervening periods of quiescence during the first cycle 2000 1600 ma the singhbhum plate moved northward and collided with the chotanagpur plate this led to the tectonic emplacement of the dalma ophiolite belt and development of the f1 folds and thrusts and m1 metamorphism during the second cycle 1550 1170 ma a clockwise rotation of the singhbhum plate towards the ne generated the f2 folds and a transcurrent sinistral shear zone obduction of the continental lithosphere of this plate occurred during the third cycle 1000 850 ma as a result of its continued impingement on the chotanagpur plate in the nnw direction this is documented by the evolution of the f3 folds m3 metamorphism and the singhbhum thrust zone the quiescence periods allowed time for isostatic readjustments viz uplifts intrusions of basic dyke swarms erosion and paralic sedimentation

fe rich archean tholeiites derived from melt enriched mantle sources evidence from the kolar schist belt south india tholeiitic amphibolites in the circa 2700 ma kolar schist belt south india are intimately interlayered with minor komatiitic amphibolites the tholeiitic amphibolites which are similar to other archean tholeiitic rocks are fe enriched with feo total varying from about 9 to 13 wt olivine and plagioclase have similar calculated saturation surface temperatures ranging from about 1125 to 1225 c on many trace and major element plots there is a distinct compositional gap between the komatiitic and tholeiitic amphibolites that cannot be explained by density filtering because the calculated melt densities for the komatiitic 2 73 2 79 and tholeiitic 2 61 2 72 amphibolites nearly overlap the rare earth element ree patterns for the tholeiites are flatter and have lower light ree abundances than those for many of the associated komatiitic rocks modeling of major and trace element data suggests that the tholeiitic rocks are not related to the komatiitic rocks by 1 differentiation of magmas of

a groundwater conceptual model and karst related carbon sink for a glacierized alpine karst aquifer southwestern china summary in the jade dragon snow mountain jdsm region yunnan province sw china an extensive hydrochemical and stable isotopic study of a glacierized alpine karst aquifer was conducted during the period 2011 2014 the objectives of the study were first to establish a conceptual hydrogeological model of the karst groundwater system second to estimate the proportion of extra glacier melt water infiltrating the karst aquifer that is being induced by the regional climate warming third to calculate the karst related flux of carbon into the karst aquifer knowledge of the local hydrogeological background from previous work was the starting point of the hydrochemical and stable isotopic study some representative spring waters and recharge waters i e glacier melt water and rainwater were investigated both spatially and temporally by hydrochemical and isotopic techniques including analysis of major and some minor ions and o and h stable isotopes a conceptual hydrogeological model of a fracture diffuse flow karst groundwater aquifer was proposed the proportion of glacier melt water infiltrating into the karst aquifer was estimated by using the karst spring as a natural pluviometer and with stable isotope analysis results show that 1 the jdsm karst aquifer is a diffuse flow system 2 it has a number of discharge areas and the jinsha river is the karst drainage base level 3 the proportion of the glacier melt water penetrating the karst aquifer is 29 and 4 the karst related carbon sink is 26 67 3 44 t km 2 a 1 as co 2 which is lower than that in non glacierized karst aquifers but over ten times larger than the carbon sink flux from silicate weathering in non karst areas showing the control of both climate and lithology on the rock weathering related carbon sink and the significance of carbonate weathering in the global carbon cycle

archean metavolcanics from the rouyn noranda district abitibi greenstone belt quebec 2 mobility of trace elements and petrogenetic constraints qualitative evaluation of altered mafic pillows from the rouyn noranda district of the abitibi metavolcanic belt reveals that for low grade metamorphism the high field strength elements hfs zr y ti and the rare earth elements ree are immobile however where alteration is extreme the ree elements are leached and redeposited by carbonate rich and k rich metasomatic fluids whilst zr y and zr ti remain unchanged rubidium ba and to a lesser extent sr are mobile at all levels of alteration however provided certain filters are applied the original geochemical values of the lavas for the alkaline elements the hfs elements and the ree can be defined the geochemical variations thus identified for the volcanic series of the rouyn noranda district are ascribed to a combination of contamination and fractional crystallization of a primitive tholeiitic magma

the stable isotope evolution in shiyi glacier system during the ablation period in the north of tibetan plateau china in order to firstly explore the stable isotope evolution of shiyi glacier system in the central qilian mountains a total of 167 samples have been collected from newly deposited snow surface snow snowpits meltwater and glacier fed river water from july 2012 to november 2013 the results indicated that only the newly deposited snow in 23 november 2013 showed a significant altitude effect whereas surface snow had a reverse altitude effect owing to evaporation and sublimation in summer 2012 and 2013 the d

hydrograph separation in a mountainous catchment combining hydrochemical and isotopic tracers runoff components of the zastler catchment 18 4 km2 southern black forest germany were analysed with hydrograph separations using stable oxygen isotopes and dissolved silica it was shown that event water and components with low silica contributed only small amounts to total runoff in addition comparison of the two component hydrograph separations showed that the low silica components are generated by both event water and pre event water fractions depending on the state of the system a modified three component hydrograph separation method was introduced using dissolved silica and 18o during storm events an interaction of three runoff components having distinct silica concentrations could be shown based on the geological and geomorphological genesis of the study site it was appropriate to assign i the low silica component to the riparian zones and impermeable areas ii the medium silica component to the periglacial debris cover and iii the high silica component to the crystalline detritus and crystalline hard rock exact quantification of the runoff components remained difficult however runoff components with medium silica concentrations reacted very sensitively and intensely the contribution of this component to total runoff is comparatively large this shows the important role of the periglacial debris to runoff generation of the study site and emphasizes the importance of runoff generation processes occurring in this reservoir copyright 2000 john wiley sons ltd

geochemical patterns in norwegian greenstones representative samples of caledonian greenstones from the grong joma lokken storen stavenes and bomlo areas in central and southern norway have been analysed for major elements and over 20 trace elements ocean floor tholeiite normalized trace element patterns and chondrite normalized rare earth patterns both provide clues to the genesis original tectonic setting petrologic character and effects of alteration of these greenstones we conclude that the storen stavenes and lokken greenstones were generated at spreading axes within the caledonian ocean the grong and possibly the bomlo submarine greenstones were erupted in an island arc system and the joma and bomlo subaerial greenstones were erupted in a within plate setting the lokken greenstones may have been generated in a marginal basin whereas those from storen and stavenes were probably generated at a rapidly spreading axis in a major ocean

archean mafic metavolcanics from the rouyn noranda district abitibi greenstone belt quebec 1 mobility of the major elements reply in a suite of archean mafic pillows from the rouyn noranda region of quebec s abitibi greenstone belt including both tholeiitic and calc alkaline varieties spanning the prehnite pumpellyite to upper greenschist metamorphic facies three types of alteration can be defined i chlorite epidote actinolite ii chlorite epidote and iii chlorite sericite the number of mineral phases decreases as a result of progressive hydration from type i to type iii alteration albitization resulting from substitution of in calcic plagioclase is highly variable in type i alteration but in types ii and iii the plagioclase is totally albitized and in some cases silicified chloritization is closely linked to increasing hydration and ca leaching with mgo and feo substituting for cao in ferromagnesian minerals calcium was mobilized and carried by solutions as evidenced by the variable concentration of epidote at the margins of pillows this calcium leaching generated an excess of al2o3 with respect to the combine

palaeoproterozoic sedimentation on the singhbhum craton global context and comparison with kaapvaal the singhbhum craton has a limited palaeoproterozoic supracrustal record which suggests a three part history comprising a long period of high freeboard and palaeosol formation on granitoids subsequent rift related mafic ultramafic volcanism and subordinate sedimentation c 2 25 2 1 ga dhanjori and jagannathpur basin fills possibly also simlipal malangtoli and ongarbira basin fills which overlapped locally with mafic soil formation and a major regression at around2 0 ga followinga longhiatus theapproximately 1 6 gadhalbhum dalmasuccession was laid down probably under continental conditions this rather truncated record stands in con trast to the chronologically and geographically much more widespread supracrustal basin fills of the kaapvaal craton and there appears to be an overall poor comparison between these two early precambrian crustal blocks however on kaapvaal three analogous events are identified widespread approximately 2 2 ga mafic volcanism followed by a well developed palaeosol and a major transgression prior to 2 05 ga the three shared events between the two cratons are com patible with the postulate of a global approximate 2 45 2 2 ga shutdown of magmatic and tec tonic geodynamics with the origin of the triumvirate directly reflecting its resumption again after about 2 2 ga we recognize here that a large diversity of views on singhbhum s geodynamic history exists predicated on a lack of precise geochronology and commonly poor outcrops and the current hypotheses are presented with these factors in mind

comments on petrogeneses and the tectonic setting of columbia river basalts abstract data on major and a few trace element contents for specimens of five formational scale units of the columbia river basalt group are reviewed and compared with those for other flood basalts and the chyulu basalts of kenya flows of the grande ronde formation which constitutes more than two thirds by volume of the columbia river basalt group in several respects resemble calc alkaline rocks and they plot in the field for magmas erupted at destructive plate margins on a th hf ta diagram these features of grande ronde flows may be related to the anomalous setting of the columbia river basalt group as a whole calc alkaline characteristics are exhibited by other flood basalts but rarely to the degree shown by grande ronde flows few if any of the columbia river basalts represent primary magmas rather they generally have been affected by multi stage fractionation and perhaps also by interaction with lower crustal rocks their compositions also may reflect partial melting of fragments of subducted lithospheric slabs

fossil marginal bassin from the indian shield a model for the evolution of singhbhum precambrian belt eastern india in the eastern part of the indian shield covering shinghbhum and adjoining districts of bihar occurs the fossil marginal basin which opened up during the early proterozoic flanked by archaean continent to the south volcanism played a significant role in filling up the basin the spine of the basin is occupied by a basaltic lava pile representing a narrow oceanic sector bif and possible marginal basin ophiolites are other significant members of the basin cover the structural features and sedimentary history of the basin are characteristic for marginal basins in general identification of this marginal basin emphasises the role of plate tectonics in the evolution of the indian precambrian shield

40ar 39ar incremental heating study of mineral separates from the early archean east indian craton implications for the thermal history of a section of the singbhum granite batholithic complex 40ar 39ar incremental heating studies on mineral separates from three sets of rocks in the singbhum craton in eastern india have helped unravel the thermochronometric history of the terrane and explain an earlier discrepancy between sm nd 3800 ma and rb sr 3100 ma whole rock ages for the older metamorphic tonalitic gneiss omtg high precision plateau ages for hornblende separates from the older metamorphic group of rocks omg suggest that this unit is older than 3300 ma and that enclaves of both the omtg and omg within the batholithic complex cooled to 500 c at 3300 15 ma following engulfment in magma forming the singbhum granite sg results from a biotite separate from the omtg imply that slow cooling continued to a temperature of 300 c at 3160 ma study of a feldspar separate from the singbhum granite suggests final cooling uplift through the 150 c isotherm 660 ma ago we suggest that an earlier rb sr whole rock age of 3130 85 ma on the omtg did not yield the crystallisation a

a four component mixing model for water in a karst terrain in south central indiana usa using solute concentration and stable isotopes as tracers the study area lies in a highly karstified carbonate terrain in south central indiana sinkholes conduits and caves form large secondary pathways for the subsurface flow as a result the discharge from a main emergence point for the subsurface flow system the orangeville rise quickly responds to the storm events and shows wide variations in flow rate water chemistry and stable isotopic compositions these responses are attributed to the mixing of water in secondary pathways in the study area recharge occurs through the thick mantled karst plain and the sinkhole plains and the role of soil layer and epikarst in the recharge process is of great importance rain dic 2 hco3 mg l 13cdic 7 soil water dic 544 hco3 mg l 13cdic 14 7 epikarstic water dic 224 hco3 mg l 13cdic 13 6 and phreatic diffuse flow water dic 299 hco3 mg l 13cdic 11 8 generally showed unique and constant dissolved inorganic carbon dic and 13cdic values over time using dic and 13cdic as tracers a four component mixing model was established for the karstic flow system by constructing the discharge hydrograph separation curves the mixing ratio of each component rain 10 6 soil 3 1 epikarstic 52 3 and phreatic 34 0 water was determined for the orangeville rise discharge over the testing period of 104 h after the storm event of 10 4 90 vadose water occupied 55 4 of spring discharge and this demonstrates the importance of the unsaturated zone especially the epikarst in the karstic flow systems

characteristics of modern atmospheric dust deposition in snow in the mt yulong region southeastern tibetan plateau we evaluated the concentration size and distribution and temporal variation of insoluble dust micro particles in the snow rainfall and water taken from the areas surrounding the mt yulong to define the characteristics of modern atmospheric dust deposition and the contributions of different dust sources the mean mass concentration 4511 mu g kg 1 of micro particles with 0 57 d 26 mu m and the diameter 11 5 mu m of dust contained in the water bodies of the mt yulong are roughly similar to those observed in other sites implying that dust is primarily supplied through short range transport from proximal source regions several or hundreds of km distances the mean mass concentrations of micro particles with 0 57 d 26 mu m is lower in the rainfall than in the snow and the river water suggesting the rain water is an ideal source carrier for detecting the characteristics of modern atmospheric micro particles volume size distributions of micro particles in the snow and water showed single modal structures having volume median diameters from 3 to 26 gm number concentrations of micro particles in the snow were higher than that in the rainfall the river water contains the least amount of microparticles vertical profiles of the snowpits show that there is a strong lateral correlation among the dust peaks indicating a regional uniformity of dust deposition and suitability of snow analysis for dust deposition in addition the bare rock of snow free terrain in the mt yulong region and the mineral particles from local rock weathering are also important sources for the dust deposition c 2014 elsevier ltd all rights reserved

evaluation of the tectonic setting of precambrian dalma volcanic belt eastern india using major and trace element characters geochemical characterisation of dalma basalt the upper member of a volcanic belt occupying the spine of a precambrian basin has been used to elucidate the eruptive environment dalma basalt in general is high magnesian in character as well as depleted in incompatible elements the major and trace element distributions are strongly indicative of ocean ridge magmatism with a feeble impression of arc volcanism such a transitional tectonic environment corroborated by the overall geologic setting of the volcanic belt is strongly indicative of a marginal basin situation during proterozoic time in this part of the indian shield

geochemistry and tectonic significance of the ongarbira metavolcanic rocks singhbhum district india abstract the volcanic sedimentary sequence of ongarbira occurs to the south of the singhbhum shear zone and rests uncomformably on a basement topographic low between the chakradharpur granite and the singhbhum granite structural analysis reveals that the ongarbira synform and other adjoining structures are kilometre scale first generation folds on e w striking axial planes these structures are in marked contrast with the corresponding kilometre scale first generation folds typical of the iron ore group synclinorium towards the south of the ongarbira belt the ongarbira metavolcanic rocks exhibit a limited range of tholeitic basalt compositions the basalts are grouped according to their mg and the details of their ree patterns groups i and ii are relatively unevolved and very similar to lree and lil depleted ocean ridge tholeiites the most evolved group iii with lree enrichment is most similar to lil enriched ocean floor basalts but may be contaminated with crustal materials in general the ongarbira volcanics evolve upward stratigraphically petrogenetic major element modelling of the ongarbira basalts suggests that the primary melt was generated by batch melting 30 of lherzolite at pressures of at least 1 5 gpa sequential fractionation of ol o1 cpx pl and cpx pl followed comparison of incompatible and compatible element distributions indicates a very similar batch m melting fractional crystallization sequence for ongarbira groups i and ii basalts group iii basalts may have been derived from a batch melt initially more enriched in incompatible elements trace element discrimination of the ongarbira basalts suggests that they were generated in an extensional environment primordial mantle normalized element distributions indicate that the basalts are similar to continental rift basalts but with oceanic affinities the chemical data along with the associated sediments indicate that the ongarbira basalts were probably emplaced in a mature continental rift although a back arc origin cannot be completely disregarded it is concluded that the ongarbira volcanics were emplaced as part of the same rifting event that resulted in outpourings of the proterozoic dalma and dhanjori volcanics implying that the ongarbira suite is proterozoic and not part of the archaean iron ore group the structural geometry of the ongarbira rocks is more conformable to that of the singhbhum mobile belt than to the iron ore group synclinorium in the singhbhum craton it is likely that the southern limit of the singhbhum mobile belt is defined by the interface of its e w structures with the nne structures of the iron ore group rocks thus the singhbhum shear zone does not mark the interface between the archaean singhbhum craton and the proterozoic singhbhum mobile belt in the eastern indian shield

changes of climate glaciers and runoff in china s monsoonal temperate glacier region during the last several decades changes of climate glaciers and runoff during the last several decades in china s monsoonal temperate glacier region have been studied temperature has increased in a fluctuating manner during the last several decades and temperature rise has accelerated since the 1980s net accumulation of dasuopu ice core has consistently declined and the precipitation decrease was also obvious from the end of 1970s through the middle 1980s and particularly after the 1990s in china s monsoonal temperate glacier region as a response to climate change eight monsoonal temperate glaciers were stationary or advancing between the 1900s 1930s and the 1960s 1980s and were in retreat from the 1930s to the 1960s and from the 1980s to the present ablation is heavy in the glacier tongue areas and the mean ablation water equivalent in hailuogou glacier during 1990 91 1997 98 was 876 mm more than that in 1982 83 ablation depth on the exposed ice area increased by 1 4 m a 1 over the period 1983 84 1990 91 mass balance records also show that glaciers suffered a constant mass loss of snow and ice and the accumulated mass balance in hailuogou basin and baishui glacier no 1 was 10 83 m water equivalent in the past 45 years and 11 38 m in the past 52 years as glaciers become shorter narrower and thinner under the background of climate warming changes of internal and upper surface morphology also occurred providing evidence of the response to climatic warming in recent years local hydrological and climatic data demonstrated that in yanggong basin during 1979 2003 and hailuogou basin during 1988 2004 runoff from the glacier areas has been increasing both seasonally and annually overall it is clear that china s monsoonal temperate glaciers are losing mass and are retreating under the background of climate warming c 2009 elsevier ltd and inqua all rights reserved

characteristics of water stable isotopes and hydrograph separation in baishui catchment during the wet season in mt yulong region south western china glaciers are of crucial importance for the livelihood of the local populations which depend on their meltwater for water and energy supplies for this reason seasonal variations of oxygen 18 of glacial stream water and their sources within a small glacial catchment in south western china were investigated during the wet season the results showed significant difference of oxygen 18 existed among meltwater rainwater ground water and stream water and significantly seasonal variation of precipitation occurred during the observed period the streamflow of baishui catchment was separated into components of ice snowmelt and precipitation using oxygen 18 as shown by the result of the two component mixing model on average 53 4 of the runoff came from ice snowmelt during the wet season whereas the remaining 46 6 were contributed by precipitation in the catchment according to monthly hydrograph the contribution of snow and glacier meltwater varied from 40 7 to 62 2 and that of precipitation varied from 37 8 to 59 3 in wet season uncertainties for this separation were mainly caused by the variation of tracer concentrations the roles of glacier and snow meltwater should be noticed in water resource management in those glacial regions in south western china copyright c 2012 john wiley sons ltd

influence of pre event water on streamflow in a granitic watershed using hydrograph separation for water resources management many studies for investigating flow paths from rainfall to subsurface have been conducted for last half century a hydrograph separation based on end member mixing was carried out to evaluate the importance of the hydrological pathways providing the main sources of a small granitic watershed dorim cheon seoul an analysis of chloride oxygen 18 and deuterium isotopes from precipitation and stream water during three storms was conducted with high resolution data using 129 samples stream water collected in advance of rain event was assumed as a pre event water baseflow component according to its dry condition and isotopic values compared with the values of different time periods the contribution from vadose water was ignored due to the thin soil layer covering the study area using a two component mixing model hydrograph separation of the stream water in dorim cheon was conducted based on weighted mean values of rain water and pre event water component with the high resolution datasets as a result of the analysis with water isotopes contribution of groundwater was dominant during the entire study period 73 74 except of instant dominance of rainfall at the earliest period using chloride as a tracer for hydrograph separation a significant difference for the amount of pre event water contribution was identified this might be caused by the large variation of chloride concentration during the rain event and the end member determination

geochemistry and petrogenesis of early proterozoic amphibolites west central colorado u s a abstract early proterozoic supracrustal rocks exposed in west central colorado include amphibolites intimately associated with felsic volcanics and associated volcaniclastic sediments three successions are recognized the dubois succession 1770 1760 ma is comprised chiefly of amphibolites and felsic volcanics the amphibolites exhibit low concentrations of light ree and hfse and are broadly similar in composition to tholeiites from immature island arcs and in some respects to nmorb the cochetopa succession 1745 1730 ma includes large amounts of felsic volcanics and volcaniclastic sediments together with amphibolites that exhibit variable but slight incompatible element enrichment similar to basalts from evolved island arc systems and associated back arc basins the black canyon succession is coeval with the cochetopa succession and is comprised chiefly of volcaniclastic sediments with minor amphibolite these amphibolites exhibit significant incompatible element enrichment similar to basalts from continental margin arc systems geochemical modeling indicates that the amphibolites evolved by closed system fractional crystallization of depleted for the dubois succession to variably enriched parental basalts for the cochetopa and black canyon successions chiefly at shallow depths incompatible element distributions in the amphibolites indicate that mantle sources changed with time from relatively depleted 1770 1760 ma to variable but slightly enriched 1745 1730 ma a provisional model calls upon the dubois succession forming in an island arc system followed by collision with the archean wyoming province at 1750 ma the cochetopa succession was deposited in an intra arc basin developed within a new continental margin arc and the black canyon succession formed in a back arc basin associated with this arc