the iberian type of volcano sedimentary massive sulphide deposits the iberian pyrite belt located in the sw iberian peninsula contains many paleozoic giant and supergiant massive sulphide deposits including the largest individual massive sulphide bodies on earth total ore reserves exceed 1500 mt distributed in eight supergiant deposits 100 mt and a number of other smaller deposits commonly with associated stockwork mineralizations and footwall alteration haloes massive sulphide bodies largely consist of pyrite with subordinated sphalerite galena and chalcopyrite and many other minor phases although substantial differences occur between individual deposits both in mineral abundance and spatial distribution these deposits are considered to be volcanogenic roughly similar to volcanic hosted massive sulphides vhms however our major conclusion is that the iberian type of massive sulphides must be considered as a vhms sub type transitional to shms

magmatism in the iberian pyrite belt petrological constraints on a metallogenic model igneous formations associated with massive sulphide deposits in the iberian pyrite belt ipb are essentially composed of basic lavas and dolerites and dacitic to rhyolitic volcanites intermediate lavas are subordinate the basic rocks show variable geochemical characteristics lavas and dolerites comparable to recent within plate alkaline basalts seem restricted to the western and southern parts of the ipb whereas basic rocks comparable to continental tholeiites or arc related basalts occur across the whole belt the felsic rocks are classified as calc alkaline and belong to the low al2o3 and high yb type at given sio2 al2o3 and tio2 contents they show variable zr nb and hree contents heavy rare earth element fractionation decreases from the dacites to the rhyolites gd yb n 1 whereas the negative eu anomaly becomes more pronounced the characteristics of the rhyolites are typical of sulphide fertile volcanic packages trace element modelling suggests that the felsic rocks evolved from a dacitic parent magma through fractional crystallization of hornblende and plagioclase partial melting of an amphibolite protolith which appears as the most probable model for the origin of this dacitic magma requires a high t p gradient in the crust the occurrence of alkaline basalts and continental tholeiites is consistent with formation of the ipb in a tensional tectonic setting however the associated island arc tholeiites suggest a location in a domain of plate convergence emplacement in a fore arc basin over a recently accreted crustal segment is envisaged as a possible hypothesis to account for the geological and petrological constraints a high geothermal gradient and eruption in a submarine tensional basin could have been two key ingredients for the development of massive sulphide deposits within the ipb

correlation and provenance of upper cretaceous campanian fluvial strata utah u s a from zircon u pb geochronology and petrography abstract detrital zircon and petrographic provenance analysis of upper cretaceous campanian strata corroborate correlation of the fluvial kaiparowits formation in southern utah with post castlegate strata of the mesaverde group in eastcentral utah sandstone samples of the kaiparowits formation in the kaiparowits plateau and mesaverde group neslen bluecastle tongue of castlegate farrer and tuscher formations in gray canyon north of green river utah contain six u pb detrital zircon age populations ranging in age from archean to late cretaceous thrust belt derived sublitharenite and quartzarenite of the lower part of the mesaverde group neslen and bluecastle lack or have only rare mesozoic grains but contain abundant archean proterozoic and paleozoic grains that record recycling of proterozoic paleozoic and jurassic sandstones exposed in uplifted thrust sheets to the west south and southwest derived feldspathic litharenite of the kaiparowits and farrer formations contains proterozoic grains and a diverse population of mesozoic grain ages archean grains are rare to absent maximum depositional ages interpreted from young zircon grains in two kaiparowits samples statistically overlap 40ar 39ar ages 76 74 ma from interbedded bentonitic tuffs and weighted mean ages of young grains from the farrer formation kolmogorov smirnoff statistics in conjunction with young grain ages and detrital age spectra corroborate petrographic evidence which indicates that the kaiparowits rivers were connected northward with a river system that deposited the farrer formation the young grain ages although imprecise indicate that the uppermost mesaverde group strata of the tuscher formation are younger than the kaiparowits formation and record partitioning of the former foreland basin by laramide uplifts

87sr 86sr isotope composition of bottled british mineral waters for environmental and forensic purposes mineral waters in britain show a wide range of 87 sr 86 sr isotope compositions ranging between 8 7 sr 86 sr 0 7059 from carboniferous volcanic rock sources in dunbartonshire scotland to 87 sr 86 sr 0 7207 in the dalradian aquifer of aberdeenshire scotland the 87 sr 86 sr composition of the waters shows a general correlation with the aquifer rocks resulting in the waters from older rocks having a more radiogenic signature than those from younger rocks this wide range of values means that the sr isotope composition of mineral water has applications in a number of types of studies in the modern commercial context it provides a way of fingerprinting the various mineral waters and hence provides a method for recognising and reducing fraud from an environmental perspective it provides the first spatial distribution of bio available 87 sr 86 sr in britain that can be used in modern historical and archaeological studies

marine isotope stage 3 paleotemperature inferred from reconstructing the die shan ice cap northeastern tibetan plateau glacial extent mapping and dating indicate that the local last glacial maximum llgm of the northeastern tibetan plateau occurred during mid marine isotope stage mis 3 this is asynchronous with the global last glacial maximum lgm that occurred during mis 2 the causes underlying this asynchronicity are the subject of ongoing debate and paleoclimatic reconstructions are a key to advancing understanding of the climatic influence on the spatial and temporal patterns of paleoglaciation we used multiple methods to reconstruct the equilibrium line altitude ela of the die shan paleo ice cap on the northeastern tibetan plateau and to infer past temperature for ice maximum positions believed to be mid mis 3 in age based on regional correlation geomorphic ela reconstructions combined with an energy and mass balance model yield a paleo ela of 4117 31 m asl 786 m lower than present with temperature depressions of 3 8 to similar to 4 6 degrees c compared to the present this is less than the lgm reconstruction of temperature depression inferred from other climatic proxy records on the tibetan plateau and suggests that the llgm glacial advance was a product of lower temperatures and slightly reduced precipitation compared to present whereas the lgm was a more restricted advance in which much colder conditions were combined with much lower precipitation

application of multi isotope ratios to study the source and quality of urban groundwater in metro manila philippines abstract to characterize water quality in terms of dissolved elements and to investigate both the origin of the water and the source and behavior of groundwater contaminants in metro manila 33 water groundwater and surface water samples were analyzed for ion and element concentrations h and o isotope ratios d h2o and 18o h2o so 4 2 isotope ratios 34s so 4 2 and 18o so 4 2 and sr isotope ratio 87sr 86sr the chemical measurements showed that the primary important environmental concerns within metro manila are groundwater salinization for both shallow and deep aquifers and as concentrations up to 22 5 g l in shallow groundwaters comparison of so 4 2 and sr isotope values with possible source materials revealed that contamination by man made materials such as fertilizers and detergents are present in some shallow groundwaters shallow groundwater having higher d h2o and 18o h2o values av 44 5 6 and 6 8 0 6 respectively n 15 than deep groundwater av 48 4 4 and 7 4 0 7 respectively n 7 suggests that the origins of h2o in both groundwaters are different from each other since the mixing of shallow and deep groundwater does not commonly occur under metro manila the contaminants in the shallow aquifers are unlikely to be transported into the deep aquifers sulfate reduction by bacterial activity was observed for some groundwaters resulting in a maximum elevation in 34s so 4 2 values of around 10 by using so 4 2 isotope ratios as an indicator of changes in redox conditions and sr isotope ratio as a source indicator it was shown that as was dissolved from unconsolidated sedimentary deposits of volcanic origin which enclose shallow unconfined aquifers but was not the result of changes in redox conditions the study demonstrated that multi isotope ratios are useful for evaluating water quality problems in urban groundwaters

landscape response to pleistocene holocene precipitation change in the western cordillera peru 10be concentrations in modern sediments and terrace fills 1 the landscape response to climate change is frequently investigated with models because natural experiments on geologic timescales are rare in quebrada veladera in the western andes mountains the formation of alluvial terraces during periods of high precipitation presents opportunities for such an experiment we compare drainage average erosion rates during pleistocene terrace deposition with holocene rates using cosmogenic 10be samples for seven pairs of quartz sand taken from the trunk and tributaries of quebrada veladera and adjacent terraces each pair consists of sediment collected from the modern channel and excavated from an adjacent fill terrace the terrace fill was deposited at 16 ka and preserved an isotopic record of paleoerosion rates in the late pleistocene modern sands yield 10be concentrations between 1 68 105 and 2 28 105 atoms g corresponding to holocene erosion rates between 43 3 and 58 4 mm kyr the 10be concentrations in terrace sands range from 9 46 104 to 3 73 105 atoms g corresponding to paleoerosion rates from 27 2 to 103 8 mm kyr smaller upstream tributaries show a substantial decline in erosion rate following the transition from a wet to dry climate but larger drainage areas show no change we interpret this trend to indicate that the wetter climate drove landscape dissection which ceased with the return to dry conditions as channel heads propagated upslope erosion accelerated in low order drainages before higher order ones this contrast disappeared when the drainage network ceased to expand at that point erosion rates became spatially uniform consistent with the uniformity of modern hillslope gradients

acidification processes and soil leaching influenced by agricultural practices revealed by strontium isotopic ratios abstract in natural river systems the chemical and isotopic composition of stream and ground waters are mainly controlled by the geology and water rock interactions the leaching of major cations from soils has been recognized as a possible consequence of acidic deposition from atmosphere for over 30 years moreover in agricultural areas the application of physiological acid fertilizers and nitrogen fertilizers in the ammonia form may enhance the cation leaching through the soil profile into ground and surface waters this origin of leached cations has been studied on two small and adjacent agricultural catchments in brittany western france the study catchments are drained by two first order streams and mainly covered with cambisoils issued from the alteration and weathering of a granodiorite basement precipitations soil water and nh4 acetate leachates separated minerals and stream waters have been investigated chemical element ratios such as ba sr na sr and ca sr ratios as well as sr isotopic ratios are used to constrain the relative contribution from potential sources of stream water elements based on sr isotopic ratio and element concentration soil water and nh4 acetate leaching indicates 1 a dominant manure slurry contribution in the top soil representing a cation concentrated pool with low 87sr 86sr ratios 2 in subsoils mineral dissolution is enhanced by fertilizer application becoming the unique source of cations in the saprolite the relatively high weathering rates encountered implies significant sources of cations which are not accessory minerals but rather plagioclase and biotite dissolution stream water has a very different isotopic and chemical composition compared to soil water leaching suggesting that stream water chemistry is dominated by elements issued from mineral and rock weathering agriculture by applications of chemical and organic fertilizers can influence the export of major base cations such as na plagioclase dissolution rather than anthropogenically controlled soil water seems to be the dominant source of na in streams however ca2 in streams is mostly derived from slurries and manures deposited on top soils and transferred into the soil ion exchange pool and stream waters less than 10 of na 5 40 of sr2 and 20 100 of ca2 found in streams can be directly derived from the application of organic fertilizers

modern and last local glacial maximum snowlines in the central andes of peru bolivia and northern chile late pleistocene snowlines in the central andes were 500 1200 m lower than at present radiocarbon dates imply that the late pleistocene glacial maximum in the region occurred prior to 20 14c ka but lack of maximum limiting ages adds considerable uncertainty to the exact timing snowline modeling demonstrates that snowlines in the eastern and western cordilleras of the central andes respond differently to temperature and precipitation changes in the eastern cordillera the snowline is near the level of the annual 0 c isotherm and melting occurs throughout the year here snowlines are sensitive to temperature changes but relatively insensitive to accumulation changes in the western cordillera the snowline rises 1000 higher owing to increasing aridity and the snowline exhibits a much stronger sensitivity to accumulation changes the consistent 1200 m snowline depression along the eastern cordilleras of the central andes can be modeled by a mean annual cooling of 5 9 c this is inconsistent with the 2 c cooling in tropical sea surface temperatures suggested by climap reconstructions the 800 1000 m snowline depression in the western cordillera cannot be accounted for solely by cooling but also requires an increase in precipitation

interactions between axial and transverse drainage systems in the late cretaceous cordilleran foreland basin evidence from detrital zircons in the straight cliffs formation southern utah usa new detrital zircon geochronologic data from the straight cliffs formation of southern utah provide insight into the controls on stratigraphic architecture of the western interior basin during turonian early campanian time detrital zircon ages n 40 n 3650 derived from linked fluvial and shallow marine depositional systems of the kaiparowits plateau indicate the majority of zircons in fluvial strata were derived from the mogollon highlands 1 25 1 90 ga 67 of fluvial zircons with subordinate contributions delivered from the sevier fold and thrust belt 265 1250 ma 17 and cordilleran magmatic sources 81 265 ma 16 integration of these data with fluvial facies distributions petrography clast counts and evidence of magmatic arc sources from the mohave region of california implies the presence of a northeast flowing axial fluvial system this system was fed by rivers draining the mogollon highlands to the south and by transverse drainages from the sevier fold and thrust belt to the west compared to the fluvial deposits shallow marine sandstones have a greater proportion of sevier fold and thrust belt derived zircons 42 which were delivered via longshore currents from the north shallow marine samples also contain less mogollon input 44 compared to contemporaneous fluvial systems and similar input from the magmatic arc 14 although proterozoic zircons associated with the mogollon highlands are also present in the sevier fold and thrust belt several lines of evidence argue for a distinct southerly source for the straight cliffs formation these include 1 moderate proportions of feldspar and angular quartz grains in fluvial sandstones which favor a felsic intrusive source and 2 prominent 1 4 and 1 7 ga zircon populations the 1 4 and 1 7 ga peaks are the only dominant proterozoic peaks in samples from the straight cliffs formation whereas samples derived more directly from the sevier fold and thrust belt tend to have a broader distribution of proterozoic age peaks up section architectural trends in the straight cliffs formation are linked to trends in detrital zircon geochronologic data underscoring the likelihood of common drivers and controls the axial system depositing straight cliffs fluvial strata was primarily fed by drainages originating in the mogollon highlands during a pulse of tectonic activity in the maria fold and thrust belt and generally high subsidence rates in the foreland basin turonian santonian over time activation of the paxton duplex in the sevier fold and thrust belt early campanian exhumed proximal foreland basin strata and enabled drainage systems from the sevier fold and thrust belt to feed into the basin more prominently the results presented here underscore the potential significance of axial fluvial systems and their complex interplay with transverse drainage networks in foreland basins

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

weathering rates and 87sr 86sr ratios an isotopic approach the 87sr 86sr ratios of precipitation throughfall groundwater streamwater and mineral matter were analyzed precipitation strontium ratios are around 0 71 throughfall which is affected by strontium from the mineral soil has ratios of 0 72 0 73 and shallow groundwater in a drug well and runoff have ratios around 0 73 0 74 there is a tendency for this relationship to be reversed for discharge higher ratios are associated with lower discharges water from a fracture zone gave the highest value 0 78 approaching the value of the bedrock around 0 85 a calcium budget which reflects the mean conditions over a few years has been calculated this budget indicates that weathering should be of the order of 8 kg ca ha 1yr 1 to maintain the pool of exchangeable calcium at a constant level the major anion in the runoff is suphate which has entered the system in the form of acid rain sulphur deposition has been rather constant over the last two decades if acidification had an effect on weathering of silicates this would have shown up in a tendency of the strontium isotope ratios toward higher values in the soil pool and in runoff water thus its seems from the observed ratios that at least a major portion of the excess calcium export resulting from sulphur deposition is taken from the soil pool resulting in a gradual acidification of the soil

sr isotope tracing of aquifer interactions in an area of accelerating coal bed methane production powder river basin wyoming sr isotope data on groundwater samples from coal and overlying sandstone aquifers in the eastern powder river basin wyoming demonstrate that the sr isotope ratio effectively identifies groundwater from different aquifers where major ion geochemistry and o and h stable isotope data fail groundwaters from sandstone aquifers have a uniform 87sr 86sr ratio of 0 7126 0 7127 waters from coal seams vary from 87sr 86sr ratio 0 7127 near the recharge area to 0 7151 farther into the basin the distinct sr isotope signatures of sandstone and coal aquifers may reflect different sources of sr in these two rock types sr in sandstones is held primarily in carbonate cement whereas coals contain more radiogenic sr in organic matter the sr isotope ratio is useful in identifying wells that contain mixed waters whether due to well construction or to incomplete aquifer isolation measurement and continued monitoring of the sr isotope ratio in groundwaters should provide a powerful tool for characterizing the impact of the burgeoning coal bed methane industry on the hydrology of the powder river basin

strontium isotope quantification of siderite brine and acid mine drainage contributions to abandoned gas well discharges in the appalachian plateau unplugged abandoned oil and gas wells in the appalachian region can serve as conduits for the movement of waters impacted by fossil fuel extraction strontium isotope and geochemical analysis indicate that artesian discharges of water with high total dissolved solids tds from a series of gas wells in western pennsylvania result from the infiltration of acidic low fe fe 10 mg l coal mine drainage amd into shallow siderite iron carbonate cemented sandstone aquifers the acidity from the amd promotes dissolution of the carbonate and metal and sulfate contaminated waters rise to the surface through compromised abandoned gas well casings strontium isotope mixing models suggest that neither upward migration of oil and gas brines from devonian reservoirs associated with the wells nor dissolution of abundant nodular siderite present in the mine spoil through which recharge water percolates contribute significantly to the artesian gas well discharges natural sr isotope composition can be a sensitive tool in the characterization of complex groundwater interactions and can be used to distinguish between inputs from deep and shallow contamination sources as well as between groundwater and mineralogically similar but stratigraphically distinct rock units this is of particular relevance to regions such as the appalachian basin where a legacy of coal oil and gas exploration is coupled with ongoing and future natural gas drilling into deep reservoirs

tracking mammoths and mastodons reconstruction of migratory behavior using strontium isotope ratios variations in the strontium isotope ratio 87 sr 86 sr of tooth enamel are used to examine the migration patterns of late pleistocene mammoths and mastodons from florida an animal s 87 sr 86 sr ratio tracks the ratios of its environment which vary with differences in bedrock and soil consequently the environmentally controlled differences in 87 sr 86 sr ratio recorded in mineralized tissue such as tooth enamel may be used to reconstruct the movement patterns of an individual we map variations in local 87 sr 86 sr ratios across modern florida and georgia through analysis of rodent teeth plants and surface water then use this map to interpret the movement patterns of extinct mammals mastodons from northern and central florida have higher 87 sr 86 sr ratios than both modern environmental samples from florida and fossils from nonmigratory species suggesting that mastodons migrated north into georgia mammoths display ratios similar to those of environmental samples and resident species suggesting that they did not migrate outside florida

integrating sandstone petrology and nonmarine sequence stratigraphy application to the late cretaceous fluvial systems of southwestern utah u s a abstract petrographic and dispersal data are essential to correct interpretation of mechanisms that create continental sequence stratigraphic architecture a case study from southern utah demonstrates that upper cretaceous upper santonian campanian alluvial successions in the southernmost part of the cordilleran foreland basin were deposited by fluvial systems of contrasting drainage directions and provenance and suggests that different mechanisms governed their sequence architecture most of the rivers flowed northeast subparallel to the basin foredeep less common fluvial systems flowed to the east southeast the fluvial sandstones fall naturally into four petrofacies 1 quartzofeldspatholithic mean qt61f19l20 2 feldspatholithic qt29f19l52 3 quartzolithic qt75f6l20 and 4 quartzose qt99f1l1 petrofacies 1 and 2 were derived from mixed supracrustal and basement sources to the southwest and south respectively whereas petrofacies 3 and 4 were derived from uplifted thrust sheets of the sevier orogenic belt to the southwest and west respectively only the east southeast flowing rivers transported the quartzose petrofacies the fluvial strata which include the uppermost straight cliffs wahweap and kaiparowits formations form two large scale stratigraphic successions typically interpreted as continental stratigraphic sequences hundreds of meters thick each succession begins with an amalgamated braided fluvial deposit grades to mudstone rich strata with low sandstone body connectivity and culminates in highly connected sandstone bodies with multistory stacking the basal amalgamated deposits of each succession are architecturally similar but their compositional and dispersal characteristics are different quartzofeldspatholithic quartzolithic and quartzose sandstones above the lower base level shift are variable but generally similar in compositional and dispersal characteristics to both underlying and overlying strata a phenomenon termed here congruence in contrast quartzose amalgamated fluvial sandstone above the upper base level shift differs sharply in composition and dispersal direction from underlying and overlying lithic rich strata the foredeep axis controlled the progradation direction of the congruent shift which was likely driven by climatically induced sediment influx a eustatic fall or both in the case of the incongruent shift increased sediment supply permitted the rivers to cross the foredeep temporal association of the upper amalgamated deposit with active structures in the thrust belt and foreland basin indicates that syntectonic thrust uplift not isostatic uplift or climate caused the influx of quartz

snowline depression in the tropics during the last glaciation five primary methods have been used to reconstruct pleistocene snowlines or equilibrium line altitudes elas in the tropics 23 53n 23 53s during the last glaciation but each has inherent errors that limit the accuracy of the results additional potential errorsin determiningela depression involveestimates of modernsnowline altitude datingresolution topographicreconstructionof former glaciers orographic e ects the presence of rockfall debris on glaciers and calculation of regional ela gradients eustatic sea level lowering during the last glaciation is an additional factor in uencing estimates of ela depression ela in cases where modern snowline lies above a mountain summit only a minimum value for ela can be obtained at 12 tropical sites in africa the americas to 103s latitude and paci c islands estimates of average ela range from 440 to 1400m but most fall in the range of 800 1000m mean 1 900 135m in a regional study of ela depression in the southern tropical andes 8 223s an average ela of ca 920 250m has been reported based on the assumption that glacier mass balance was controlled solely by ablation season temperature and assuming a full glacial temperature lapse rate of 63c km depression of mean annual temperature in glaciated alpine areas was ca 5 4 0 83c if adjusted for a sea level fall of 120m at the glacial maximum this value is reduced to 4 7 0 83c the gure is based on the unlikely assumption that accumulation on alpine glaciers has been invariant nevertheless it is similar to values of temperaturedepresson 5 6 43c for the last glaciationobtainedfrom variousterrestrial sites but contrasts with tropical sea surface temperature estimates that are only 1 33c cooler than present 2001 elsevier science ltd all rights reserved

equilibrium line altitudes of the last glacial maximum for the himalaya and tibet an assessment and evaluation of results abstract contemporary equilibrium line altitudes elas for glaciers in the high mountains of the himalaya and tibet have considerable variation because the region is influenced by two major climatic systems the mid latitude westerlies and the south asian summer monsoon and glaciers are subject to strong topographic controls reconstructions of past elas based on the former extent of glaciers are numerous but were estimated using a variety of methods some of which are not appropriate for high altitude glaciers which are strongly influenced by topography and have extensive supraglacial debris cover furthermore few of the reconstructions have adequate chronological control because of the difficulty of dating glacial landforms in high altitude regions where organic matter for radiocarbon dating is sparse or absent cosmogenic radionuclide surface exposure and optically stimulated luminescence dating are providing data to define the timing of glaciation and these together with objective analysis of glacier dynamics may allow better estimates of ela changes in the future however there are currently only two regions the hunza valley and the khumbu himal which are sufficiently well dated to allow reconstructions of last glacial maximum glacier extent and hence elas these two regions cannot provide an adequate assessment of ela changes for the himalayan tibetan region

spatial variation of strontium isotopes 87sr 86sr in the maya region a tool for tracking ancient human migration strontium isotope ratios 87sr 86sr in human bones and teeth have become a useful tool to study migration and sedentism of individuals from archaeological contexts here we analyzed 87sr 86sr of water bedrock soils and plants across a broad geographic region to test the potential of this method in the ancient maya area our aims were two fold first to test if the sources of dietary strontium i e plants and water in humans reflect the 87sr 86sr ratio of exposed bedrock and second to determine whether the ranges of 87sr 86sr values were sufficiently distinct among the principal maya geocultural areas to infer past migration we identified five distinct subregions on the basis of geologic maps and evaluated the variability of 87sr 86sr values values given as mean 87sr 86sr 2 standard deviations number of samples 1 northern lowlands 0 70888 0 00066 n 16 2 southern lowlands 0 70770 0 00052 n 86 3 volcanic highlands and pacific coast 0 70415 0 00023 n 34 4 metamorphic province 0 70743 0 00572 n 50 and 5 the maya mountains of belize 0 71327 0 00167 n 3 although the sample size is small and overlap exists in 87sr 86sr values among some subregions most areas can be readily distinguished from one another on the basis of strontium isotopes these subregional 87sr 86sr differences provide archaeologists with a powerful tool to recognize geographic outliers in ancient maya burials and thereby test hypotheses concerning the origin of specific individuals inferred population migration patterns and the possibility of outside cultural influences in the maya region

geochemical correlation in deltaic successions a reality check whole rock geochemical analysis can aid the stratigraphic correlation of faunally barren successions compared to petrographic techniques or heavy mineral separations such analysis is quick and objective yet rarely has the reliability of the method been tested against unequivocal correlations we have applied it to the kenilworth member of the upper cretaceous blackhawk formation a well exposed and easily correlated 100 m thick unit in the deltaic successions of the book cliffs utah united states this is the first evaluation of geochemical analysis as an aid to sequence stratigraphic interpretation at the parasequence scale from the geochemistry alone it is not possible with statistical confidence to separate individual parasequences or systems tracts nor the fluvial incised valley from the marine shoreface units the magnitude of geochemical variation in a single sandstone bed over a 30 m lateral traverse is as great as vertically through an entire parasequence y nb rb and ti abundances are inversely correlated with grain size thus geochemical signatures follow sedimentological trends and distal parts of a parasequence appear distinct from proximal parts y ratios compensate for this grain size effect but introduce confusing distortions for elements such as zr that are not correlated with grain size contrary to some predictions zr is as common in the finest grained units as the coarsest and sr is not correlated with ca in some sections sr is also inversely correlated to grain size and cannot be used as an indicator for cement abundance

northern latitude chemical weathering rates clues from the mackenzie river basin canada abstract the main scope of this study is to investigate parameters controlling chemical weathering rates for a large river system submitted to subarctic climate more than 110 river water samples from the mackenzie river system northern canada have been sampled and analyzed for major and trace elements and sr isotopic ratios in the dissolved phase the three main morphological units are reflected in water chemistry rivers from the canadian shield are very dilute dominated by silicate weathering millot et al 2002 whereas the rivers of the rocky and mackenzie mountains as well as the rivers of the sedimentary interior platform are dominated by carbonate weathering and are so 4 rich compared to the rivers of the mackenzie and rocky mountains the rivers of the interior plains are organic silica and na rich and constitute the dominant input term to the mackenzie river mainstream rivers of the canadian shield area do not significantly contribute to the mackenzie river system using elemental ratios and sr isotopic ratios a mathematical inversion procedure is presented that distinguishes between solutes derived from silicate weathering and solutes derived from carbonate weathering carbonate weathering rates are mostly controlled by runoff which is higher in the mountainous part of the mackenzie basin these rates are comparable to the carbonate weathering rates of warmer areas of the world it is possible that part of the carbonate weathering is controlled by sulfide oxidative weathering but its extent remains difficult to assess conversely to what was stated by edmond and huh 1997 overall silicate weathering rates in the mackenzie basin are low ranging from 0 13 to 4 3 tons km 2 yr na k ca mg and confirm the negative action of temperature on silicate weathering rates for river basins in cold climates in contrast to what has been observed in other large river systems such as the amazon and ganges rivers silicate weathering rates appear 3 to 4 times more elevated in the plains than in the mountainous headwaters this contradicts the raymo hypothesis raymo and ruddiman 1992 isotopic characterization of suspended material clearly shows that the higher weathering rates reported for the plains are not due to the weathering of fine sediments produced in the mountains e g by glaciers and deposited in the plains rather the relatively high chemical denudation rates in the plains are attributed to lithology uncompacted shales high mechanical denudation and the abundance of soil organic matter derived from incomplete degradation and promoting crystal lattice degradation by element complexation the three to fourfold factor of chemical weathering enhancement between the plains and mountains is similar to the fourfold factor of enhancement found by moulton et al 2000 between unvegetated and vegetated watershed this study confirms the negative action of temperature on silicate weathering for cold climate but shows that additional factors such as organic matter associated with northern watersheds are able to counteract the effect of temperature this acceleration by a factor of 4 in the plains is equivalent to a 6 c increase in temperature

mapping 87sr 86sr variations in bedrock and water for large scale provenance studies abstract although variation in 87sr 86sr has been widely pursued as a tracer of provenance in environmental studies forensics archeology and food traceability accurate methods for mapping variations in environmental 87sr 86sr at regional scale are not available in this paper we build upon earlier efforts to model 87sr 86sr in bedrock by developing gis based models for sr isotopes in rock and water that include the combined effects of lithology and time using published data we fit lithology specific model parameters for generalized equations describing the concentration of radiogenic sr in silicate and carbonate rocks the new model explained more than 50 of the observed variance in measured sr isotope values from independent global databases of igneous metaigneous and carbonate rocks but performed more poorly explaining 33 of the variance for sedimentary and metasedimentary rocks in comparison a previously applied model formulation that did not include lithology specific parameters explained only 20 and 8 of the observed variance for igneous and sedimentary rocks respectively and exhibited an inverse relationship with measured carbonate rock values building upon the bedrock model we also developed and applied equations to predict the contribution of different rock types to 87sr 86sr variations in water as a function of their weathering rates and strontium content the resulting water model was compared to data from 68 catchments and shown to give more accurate predictions of stream water 87sr 86sr r2 0 70 than models that did not include lithological weathering parameters we applied these models to produce maps isoscapes predicting 87sr 86sr in bedrock and water across the contiguous usa and compared the mapped sr isotope distributions to data on sr isotope ratios of us marijuana crops although the maps produced here are demonstrably imperfect and leave significant scope for further refinement they provide an enhanced framework for lithology based sr isotope modeling and offer a baseline for provenance studies by constraining the 87sr 86sr in strontium sources at regional scales

tracking multiple sr sources through variations in 87sr 86sr ratios of surface waters from the aljustrel massive sulphide mining area geological versus anthropogenic inputs abstract this study presents major and trace element data and 87sr 86sr ratios for surface waters from a small watershed draining the aljustrel sulphide mining area south portugal the watershed is located in a geologically complex area comprising two main compartments the northern compartment is dominated by cenozoic formations and does not bear any mining activity whilst the southern compartment is underlain by rocks from both the cenozoic sedimentary cover and the mineralized sequences of the variscan paleozoic basement of the south portuguese zone based on the available geochemical and isotopic data the analysed water samples can be roughly divided into five main groups a group 1 corresponds to amd contaminated water drainages from the southern part of the catchment showing ph 8 marked depletions in so4 and heavy metals and displaying sr isotopic compositions similar to rainwater 87sr 86sr 0 7097 0 7098 c group 3 includes mixed type stream waters with ph and elemental isotopic signatures intermediate between those of groups 1 and 2 d group 4 comprises the samples collected at two lime treated water dams from the mining area that are clearly distinguished from the impacted waters of group 1 by their elevated ca mg and sr concentrations and low 87sr 86sr ratios 87sr 86sr 0 7085 0 7091 e group 5 includes clean waters from two dams located upstream of the ore processing site which are dominantly supplied by direct precipitation and surface runoff and have ph 6 very low so4 and metal concentrations and 87sr 86sr ratios varying between 0 7094 and 0 7108 variations in the 87sr 86sr ratios and sr concentrations of the analysed waters are attributed to mixing of two main end members atmospheric meteoric waters local rainfall runoff with low sr contents and 87sr 86sr ratios 0 7095 and more radiogenic waters derived from the aljustrel mining area the highly radiogenic signatures of the southern tributaries appear to have been controlled by weathering of plagioclase from the acid volcanic rocks of the paleozoic basement enhanced by mining activities pyrite oxidation although released strontium from gangue carbonates could have locally contributed to the fluctuations of sr contents and 87sr 86sr ratios observed in some of these water samples by contrast the low 87sr 86sr ratios and relatively high sr cl and na concentrations shown by the surface waters draining the northern compartment suggest that these tributaries correspond to meteoric waters that have gained cl na and sr through wash out of cenozoic deposits containing finely disseminated halite layers finally the decrease in the 87sr 86sr ratios and elevation of sr contents observed in the samples from the lime treated water dams support the involvement of an anthropogenic source of sr with 87sr 86sr ratios lower than that of rainfall

far traveled latest cretaceous paleocene conglomerates of the southern rocky mountains usa record of transient laramide tectonism a solitary thin widespread conglomerate is found in latest cretaceous paleocene sections in each of these laramide basins of the southern rockies the table cliff northwestern kaiparowits plateau and uinta basin utah the piceance creek and denver basins colorado and the san juan basin new mexico these units are unusual compared to typical syntectonic conglomerates in that they occur as a thin interval underlain by a disconformity are far traveled across most of the length of their basins generally reflect a change in dispersal direction relative to underlying deposits and were deposited during a period of reduced subsidence all units were deposited well after local initiation of the laramide orogeny but within 8 m y of each other however each conglomerate unit was separately derived from individual source areas and is not part of a once continuous gravel sheet similar widespread conglomerate units of this age are apparently absent in other rocky mountain laramide basins previous studies postulate the shallow subduction of an oceanic plateau the conjugate shatsky rise beneath the u s cordillera during the time interval of conglomerate deposition the distribution timing and dispersion directions of the far traveled conglomerates are grossly consistent with vertical motions and surface tilting along the transport path of the oceanic plateau an exact match of conglomerate timing differs from previously proposed models but uncertainties in timing of deposits and the lack of constraints on the shape and structure of the subducted plateau preclude our ability to further refine the comparison elsewise local tectonic activity climate change and sea level fluctuations fail to explain the observed spatiotemporal pattern hence we suggest that these deposits record a transient mantle derived tectonic effect traversing the rocky mountain region and demonstrate the utility of stratigraphy as a record of subtle tectonic events

unroofing incision and uplift history of the southwestern colorado plateau from apatite u th he thermochronometry the source of buoyancy for the uplift of cratonic plateaus is a fundamental question in continental dynamics the 1 9 km uplift of the colorado plateau since the late cretaceous is a prime example of this problem we used apatite u th he thermochronometry 230 analyses 36 samples to provide the fi rst single system regional scale proxy for the unroofi ng history of the southwestern quadrant of the plateau the results confi rm overall southwest to northeast unroofi ng from plateau margin to plateau interior a single phase of unroofi ng along the plateau margin in late cretaceous to early tertiary sevierlaramide time contrasts with multiphase unroofi ng of the southwestern plateau interior in early and mid to late tertiary time the early cretaceous was characterized by northeastward tilting and regional erosion followed by aggradation of 1500 m of upper cretaceous sediments along the eroded plateau margin sevier laramide denudation affected the entire southwestern plateau was concentrated along the plateau margin and migrated from northwest to southeast following a period of relative stability of the landscape from ca 50 30 ma signifi cant unroofi ng of the southwestern plateau interior occurred between ca 28 and 16 ma additional denudation north of the grand canyon took place in latest tertiary time mid tertiary dates from the grand canyon basement at the bottom of the upper granite gorge limit signifi cant incision of the modern grand canyon below the kaibab surface to 1500 m difference in vertical structural position if these models are correct they indicate that a proto grand canyon of kilometer scale depth had incised post paleozoic strata by the early eocene evidence for kilometerscale mid tertiary relief in northeast fl owing drainages along the plateau margin as well as the mid tertiary episode of plateau interior unroofi ng imply that the southwestern plateau interior had attained substantial elevation by at least 25 20 ma if not much earlier these observations are inconsistent with any model calling for exclusively late tertiary uplift of the southwestern plateau sevier laramide plateau surface uplift and incision thus result from one or more processes that enhanced the buoyancy of the plateau lithosphere expanding the cordillera s orogenic highlands into its lowstanding cratonic foreland the onset of the laramide slab s demise at ca 40 ma and the major pulse of extension in the basin and range from ca 16 10 ma appear to have had little infl uence on the denudation history of the southwestern plateau in contrast the post laramide unroofi ng episodes may be explained by drainage adjustments induced by rift related lowering of regions adjacent to the plateau without the need to otherwise modify the plateau lithosphere our data do not preclude a large component of post early eocene elevation gain or the geodynamic mechanisms it may imply but they do point toward laramide age buoyancy sources as the initial cause of signifi cant surface uplift ending more than 500 m y of residence near sea level

mid mis3 climate inferred from reconstructing the dalijia shan ice cap north eastern tibetan plateau the local last glacial maximum lgml on dalijia shan occurred during mid marine isotope stage 3 mis3 which is consistent with some tibetan plateau records but asynchronous with the mis2 global last glacial maximum lgmg paleoclimatic reconstructions are key to advancing understanding such spatial and temporal patterns of paleoglaciation using multiple methods we reconstructed mid mis3 equilibrium line altitude ela on dalijia shan and inferred temperature depressions geomorphic ela reconstructions combined with empirical data on current ela temperature and precipitation yield a mid mis3 ela of 4000 78 m a s l 618 851 m lower than current and a temperature depression of 3 3 6 8 c independent glacial modeling using the degree day approach suggests a mid mis3 ela between 3971 and 4024 m a s l and a temperature depression of 4 2 5 6 c the consistency of these results indicate that mid mis3 temperature depressions in the dalijia shan region were 3 3 6 8 c which is less than the lgmg temperature depression inferred from regional climatic proxy data combined with other proxy data this suggests that the lgml glacial advance in dalijia shan resulted from lower temperatures and slightly reduced precipitation compared with present whereas the lgmg advance was more restricted because much colder conditions were combined with much lower precipitation

isotope and minor element geochemistry of high arsenic groundwater from hangjinhouqi the hetao plain inner mongolia abstract high as groundwater is widely distributed in the northwestern hetao plain an arid region with slow groundwater flow arsenic concentration in groundwater ranges from 1 to 1000 g l most water samples have elevated salinities with cl and or hco 3 as the dominant anions and na as the dominant cation high concentrations of as in shallow aquifers are associated with strongly reducing conditions as evidenced by high concentrations of dissolved organic c doc nh 4 dissolved sulfide arsenite and dissolved ch 4 and relatively low concentrations of no 3 and so 4 2 results of the hydrochemical and h and o isotope geochemical studies indicate that evapotranspiration is an important process controlling the enrichment of na and cl as well as trace elements such as as b f and br in groundwater in na hco 3 dominated groundwaters as b and f were enriched decades of irrigation using yellow river water has resulted in elevation of the groundwater level which has accelerated salt accumulation in shallow groundwater and surface soil in addition irrigation is responsible for the release of some components from aquifer materials and mixing with saline groundwaters as indicated by minor element and isotope geochemical data used to trace groundwater flow paths sr isotope composition also indicates that bedrock weathering is one of the primary sources of as in groundwater in the study area

strontium isotope variation and carbonate versus silicate weathering in rivers from across alaska implications for provenance studies abstract the characterization of strontium sr isotopic 87 sr 86 sr variation in surface waters of alaska ak has significant implications for provenance studies aiming to track movement patterns of animals this study presents 87 sr 86 sr ratios concentrations of sr ca mg na and k and selected molar ratios sr na ca na mg na and ca sr from 61 rivers from across ak to characterize regional patterns in i 87 sr 86 sr variation and ii carbonate versus silicate weathering influencing 87 sr 86 sr ratios 87 sr 86 sr ratios range from 0 70422 0 74041 0 00009 rivers north of the denali fault exhibit more radiogenic and variable 87 sr 86 sr ratios 0 70763 to 0 74041 than rivers to the south 0 70422 to 0 70895 reflecting the tectonic growth of southern ak via accretion of relatively young mafic rich exotic island arcs along north america s continental margin during the mesozoic within interior ak an east west gradient exists radiogenic 87 sr 86 sr ratios 0 725 in east central ak and relatively low ratios 0 711 than lowland rivers 87 sr 86 sr ratios in high relief watersheds north of the denali fault and in watersheds of south central ak elemental and 87 sr 86 sr ratios indicate silicate weathering is important across ak but is most influential in lowland basins north of the denali fault and in southwestern ak this study illustrates the large sr isotopic heterogeneity across ak on multiple spatial scales and provides necessary baseline information for provenance studies

hydrothermal alteration and mineralization in the neves corvo volcanic hosted massive sulfide deposit portugal i geology mineralogy and geochemistry the neves corvo volcanic hosted massive sulfide deposit is one of the largest 300 mt and richest known deposits of the iberian pyrite belt the deposit is unique because of its extremely high cu and sn grades 45 mt at 6 cu plus 4 5 mt at 12 cu and 2 2 sn more than 300 000 metric tons t of tin metal is contained in several types of tin mineralization that grade from 500 ppm to 60 percent sn the deposit consists of five orebodies including corvo the focus of the present study the volcanic volcaniclastic and sedimentary lithofacies that directly host the neves corvo mineralization consist of a rhyolitic dome cryptodome hyaloclastite complex facies interpretation indicates that volcanic activity occurred at moderate water depth below storm wave base in variably subsiding basins of different orders several syn and postore modification events included gravity driven mass transport processes and subsequent low angle thrusting and asymmetric detachment folding which shaped the present deposit the ore geology and geochemistry and the textural mineralogical and geochemical aspects of the ore forming process in the corvo orebody collectively suggest that ore formation resulted from a long lived hydrothermal system including two main mineralizing events an early stage of stringer and massive cassiterite deposition and a subsequent episode of massive sulfide ore generation two spatially independent stockworks fed these genetically related mineralizing systems the early deposition of stringer and massive cassiterite ores took place almost exclusively in the tin corridor a structural alignment bounded by synvolcanic faults textural analysis and geochemical data both indicate minimal fluid rock interaction during ascent of the tin bearing fluid the massive and semimassive cassiterite ores at corvo most likely formed by direct venting into seawater and or emplacement in water laden unlithified sediments and early hydrothermal products that mantled the footwall volcanic sequence stringer and massive cassiterite precipitation is thought to have been a product of a short lived episode in the overall ore forming system the vein filling mineral assemblage in the cassiterite stockwork quartz cassiterite pyrite donbassite kaolinite chamosite coupled with whole rock and mineral geochemical data indicate that the tin bearing fluid had a low ph and relatively high temperature 380 c the massive sulfide related hydrothermal alteration in corvo is essentially strata bound the permeability contrasts in the uppermost portion of the footwall succession played an important role in controlling the fluid flow the hydrothermal alteration is zoned and consists of an inner chlorite donbassite quartz sulfide sericite core that grades outward into successive enveloping k sericite quartz sulfide and na sericite quartz sulfide halos textural evidence from the mine to the microscopic scale and mass balance considerations indicate that extensive silicate replacement in the coherent volcanic rocks of the footwall sequence and disseminated replacement mineralization in the uppermost volcaniclastic and or sedimentary units were major mechanisms of massive sulfide deposition at corvo alteration mineralogy and geochemistry indicate that the neves corvo ore fluids were hotter and more acidic than typical ore forming fluids of the iberian pyrite belt the geochemical characteristics of the tin and copper mineralization also differ from the ores of typical deposits of the iberian pyrite belt and imply the involvement of additional metal sources possibly magmatic in the ore forming system copper enrichment due to mechanical and fluid assisted tectonometamorphic remobilization processes accounts for the formation of extremely high grade ore shoots in the deposit

strontium isotope compositions of river waters as records of lithology dependent mass transfers the garonne river and its tributaries sw france the relation of lithology in the drainage basin to the dissolved load of the garonne river and its main tributaries in southwestern france was evaluated by determining 87sr 86sr ratios and concentrations of major and trace elements during a 2 year long survey in the upper drainage basin the garonne river waters were isotopically varied at two observation points 0 71131 0 00030 2 for 84 18 ppb 2 and 0 71272 0 00044 for 86 10 ppb respectively in the lower drainage basin the garonne river waters were isotopically identical at three observation points at 0 71020 0 00024 for 125 22 ppb by contrast the tributaries lot truyere aveyron arriege gers and salat are widely varied in their 87sr 86sr ratios and sr concentrations from 0 70836 0 00049 to 0 71058 0 00057 and from 18 8 to 280 116 ppb the sr isotope ratios and concentrations suggest a dominant supply of two reservoirs of sr one of which is with low 87sr 86sr ratios and high sr contents that is typically characteristic of carbonate rocks and the other with high 87sr 86sr ratios and low sr concentrations that is characteristic of felsic rocks locally as in the lot waters draining the massif central and within the pyrenees mountains a third source of sr from mafic rocks may be involved mass balance calculations based on the mean 87sr 86sr ratios and contents of the dissolved sr and on the mean discharges integrating the 2 year survey suggest that contribution of the silicate reservoir amounts 3 8 of the total dissolved sr flux mass balance calculations also suggest that variation in the supply of sr from either of the two major reservoirs does not exceed the analytical uncertainty at about 5 the 87sr 86sr ratios of hcl and nh4cl leachates of suspended loads of the garonne river are different from that of the associated dissolved sr this leaching related supplementary sr represents less than 10 of the total amount of sr transported by the garonne waters the sr isotope characteristics of the leachates are probably records of an intermediate pedogenic episode in the weathering erosion process occurring in the garonne drainage basin

hydrothermal alteration and mineralization in the neves corvo volcanic hosted massive sulfide deposit portugal ii oxygen hydrogen and carbon isotopes the oxygen hydrogen and carbon isotope compositions of hydrothermally altered rocks and minerals from massive and stockwork ores of the neves corvo volcanic hosted massive sulfide deposit have been used to infer its thermal history and the origins of the hydrothermal fluids quartz and cassiterite separated from the stringer and massive cassiterite ores of the corvo orebody tin corridor have 18o values of 12 5 to 13 6 and 1 4 to 0 4 per mil respectively quartz cassiterite oxygen isotope fractionation indicates temperatures of 174 to 207 c avg 191 c for precipitation of this mineral pair the calculated oxygen isotope composition of the fluid 18oh2o 0 4 to 0 7 avg 0 1 suggests that cassiterite precipitation resulted from extensive mixing of a tin bearing fluid with seawater at sea floor hydrothermal vents the whole rock oxygen isotope composition of the hydrothermally altered felsic volcanic rocks hosting the sulfide stockwork of the corvo orebody varies from the central stockwork chloritic alteration zone i 18o 8 7 9 6 to the peripheral zones sericitic and paragonitic alteration zones iia 18o 11 6 13 1 and iib 18o 11 0 14 1 the 18o values of quartz also increase from alteration zone i avg 13 9 to alteration zone iia avg 14 4 to alteration zone iib avg 15 0 quartz from the hanging wall jasper unit yielded higher 18o values of 15 5 to 17 9 per mil chlorite from alteration zone i has 18o values of 6 1 to 8 4 per mil avg 7 4 sericite has 18o and d values that vary slightly from 18o 9 3 to 10 1 per mil avg 9 9 and d 59 to 47 per mil avg 53 in alteration zone i to 18o 9 8 to 11 4 per mil avg 10 5 and d 50 per mil in alteration zone iia to 18o 9 4 to 11 7 per mil avg 10 6 and d 61 to 36 per mil avg 45 in alteration zone iib siderite associated with waning hydrothermal activity has low 13c values 11 1 to 5 8 suggesting the incorporation of oxidized organic carbon from the footwall sequence and or the addition of magmatic carbon in alteration zone i quartz chlorite fractionation indicates temperatures of 249 to 402 c avg 335 c and 18oh2o values of 6 1 to 10 2 per mil avg 8 3 quartz sericite pairs gave isotopic equilibrium temperatures of 250 to 289 c avg 269 c and 18oh2o values of 5 8 to 7 0 per mil avg 6 4 in alteration zone iia and 170 to 318 c avg 223 c and 18oh2o 1 4 to 8 3 per mil avg 4 5 in alteration zone iib the oxygen isotope data show that in the core of the feeder system alteration zone i the temperature and the 18oh2o values were very high the d values calculated for the ore fluids d 37 to 11 are also significantly lower than seawater outward from the central stockwork alteration zones iia and iib the ore fluid was depleted in 18o and the temperatures were lower the oxygen hydrogen and carbon isotope signatures of the neves corvo ore fluids are best explained by incorporation of magmatic and or metamorphic fluids into a seawater dominated hydrothermal system magmatic fluids in particular were a likely source for the tin and much of the copper in the neves corvo ores

multiple sources for ore forming fluids in the neves corvo vhms deposit of the iberian pyrite belt portugal strontium neodymium and lead isotope evidence lead rb sr and sm nd isotopes have been used to constrain the sources and the timing of mineralisation at the neves corvo vhms deposit of the iberian pyrite belt ipb sulfide and cassiterite rich ores together with a mineralised felsic volcanic rock yield a rb sr errorchron age of 347 25 ma with an initial 87sr 86sr 0 71031 65 the rb sr results agree with palynological age constraints for ore formation at neves corvo and are indistinguishable from several other mineralisation ages indicating that major orebodies in the ipb formed coevally at 350 ma in contrast wide variations in initial 143nd 144nd indicate limited rare earth element redistribution during ore deposition initial end 350 ma values range from 0 2 to 9 7 for copper ores 8 9 to 9 4 for copper tin ores and 6 9 cassiterite to 9 5 for tin ores implying that neither the ipb volcanic host rocks end 350 ma 2 1 87sr 86sr0 0 70664 nor contemporaneous seawater 87sr 86sr0 0 708 could have been the exclusive sources for the neves corvo ores distinct mixing arrays in the end 350 ma sm nd and 206pb 204pb 207pb 204pb diagrams demonstrate that sulfide and tin ore deposition involved ore forming solutions from different sources whereas sulfide ore compositional variations are consistent with significant incorporation of typical ibp volcanic seawater derived hydrothermal components the highly radiogenic lead and exclusively low end values preserved in tin ores require a predominant derivation from external sources this could be either a magmatic source which must have been different from the typical ipb felsic magmas or a metamorphic fluid deeply circulated through older basement rocks

isotope hydrology of early paleogene lake flagstaff central utah implications for cordilleran evolution lacustrine sediments from paleogene foreland basins of the north american cordillera serve as powerful integrators of information on climatic and tectonic conditions but episodes of hydrologic connection between basins may confound straightforward interpretations we use stable isotope ratios of carbon and oxygen in authigenic carbonates of the flagstaff formation in central utah to investigate the history of the lake system which produced these sediments flagstaff limestone and dolostone exhibit isotopic compositions consistent with having formed from the same fluid at surface conditions indicating high evaporative concentration was unnecessary to drive dolomite precipitation isotopic data are consistent with the flagstaff formation having been produced by a large lake which occupied its basin from the late paleocene into the early eocene lake flagstaff was hydrologically distinct from lake uinta to the north but may have been connected to lake claron in the south paleoaltimetry estimates suggest that the mean elevation of lake flagstaff9s catchment in the sevier highlands did not exceed 1 5 km the growing evidence from stable isotope data that cordilleran elevations were relatively low in the early paleogene is in stark contrast to structural and sedimentological evidence for a high nevadaplano and a topographically rugged sevier thrust belt

sr isotopes in natural waters applications to source characterisation and water rock interaction in contrasting landscapes strontium isotopes 87sr 86sr are routinely measured in hydrochemical studies to determine sources and mixing relationships they have proved particularly useful in determining weathering processes and quantifying end member mixing processes a number of routine case studies are presented which highlight that sr isotopes represent a powerful tool in the geochemists toolbox helping to constrain weathering reactions weathering rates flow pathways and mixing scenarios differences in methodologies for determining the weathering component in natural environments inherent differences in weathering rates of different minerals and mineral heterogeneity often cause difficulties in defining the weathering component of different catchments or aquifer systems nevertheless sr isotopes are useful when combined with other hydrochemical data to constrain models of water rock interaction and mixing as well as geochemical processes such as ion exchange this paper presents a summary of recent work by the authors in constraining the sources of waters and weathering processes in surface catchments and aquifers and indicates cases where sr isotopes alone are insufficient to solve hydrological problems

controls over the strontium isotope composition of river water abstract strontium concentrations and isotope ratios have been measured in river and ground waters from the ganges orinoco and amazon river basins when compared with major element concentrations the data set has allowed a detailed examination of the controls over the strontium isotope systematics of riverine input to the oceans in the following environments 1 1 typical drainage basins containing limestones evaporites shales and alumino silicate metamorphic and igneous rocks 2 2 shield terrains containing no chemical or biogenic sediments and 3 3 the floodplains that constitute the largest areas of many large rivers the strontium concentration and isotope composition of river waters are largely defined by mixing of strontium derived from limestones and evaporites with strontium derived from silicate rocks the strontium isotope composition of the limestone endmember generally lies within the phanerozoic seawater range which buffers the 87 sr 86 sr ratios of major rivers a major exception is provided by the rivers draining the himalayas where widescale regional metamorphism appears to have led to an enrichment in limestones of radiogenic strontium derived from coexisting silicate rocks the strontium isotope systematics of rivers draining shield areas are controlled by the intense transportlimited nature of the weathering reactions and thereby limits variations in the strontium flux from these terrains floodplains are only a minor source of dissolved strontium to river waters and precipitation of soil salts in some floodplains can reduce the riverine flux of dissolved strontium to the oceans the most effective mechanisms for altering the isotope ratio and flux of riverine strontium to the oceans are increased glaciation and large scale regional metamorphism of the type produced during continental collision both mechanisms provide a means for increasing the 87 sr 86 sr ratio of the global riverine flux

tracing thermal aquifers of el chichon volcano hydrothermal system mexico with 87sr 86sr ca sr and ree abstract the volcano hydrothermal system of el chichon volcano chiapas mexico is characterized by numerous thermal manifestations including an acid lake steam vents and boiling springs in the crater and acid and neutral hot springs and steaming ground on the flanks previous research on major element chemistry reveals that thermal waters of el chichon can be divided in two groups 1 neutral waters discharging in the crater and southern slopes of the volcano with chloride content ranging from 1500 to 2200 mg l and 2 acid to neutral waters with cl up to 12 000 mg l discharging at the western slopes our work supports the concept that each group of waters is derived from a separate aquifer aq 1 and aq 2 in this study we apply sr isotopes ca sr ratios and ree abundances along with the major and trace element water chemistry in order to discriminate and characterize these two aquifers waters derived from aq 1 are characterized by 87 sr 86 sr ratios ranging from 0 70407 to 0 70419 while sr concentrations range from 0 1 to 4 mg l and ca sr weight ratios from 90 to 180 close to average values for the erupted rocks waters derived from aq 2 have 87 sr 86 sr between 0 70531 and 0 70542 high sr concentrations up to 80 mg l and ca sr ratio of 17 28 aquifer 1 is most probably shallow composed of volcanic rocks and situated beneath the crater within the volcano edifice aquifer 2 may be situated at greater depth in sedimentary rocks and by some way connected to the regional oil gas field brines the relative water output l s from both aquifers can be estimated as aq 1 aq 2 30 both aquifers are not distinguishable by their ree patterns the total concentration of ree however strongly depends on the acidity all neutral waters including high salinity waters from aq 2 have very low total ree concentrations 4 ground waters draining fresh and old pyroclastic deposits rich in magmatic anhydrite it is suggested that the main mechanism controlling the concentration of ree in waters of el chichon is the acidity as low ph results from the shallow oxidation of h 2 s contained in hydrothermal vapors ree distribution in thermal waters reflects the dissolution of volcanic rocks close to the surface or lake sediments as is the case for the crater lake

ore deposit types and tectonic evolution of the iberian pyrite belt from transtensional basins and magmatism to transpression and inversion tectonics abstract a new interpretation of the structural evolution of the iberian pyrite belt ipb and volcanogenic massive sulfide mineralization vms is presented in this work based on a review of the ore deposit types the analysis of the hosting volcanic sequences and the tectonic evolution the vms deposits of the ipb are hosted by volcanic and siliciclastic rocks four main volcano sedimentary sequences vsc from vsc0 to vsc3 have been assumed the main deposits being located in the vsc0 and at the top of the vsc2 we have defined three main sectors oriented approximately e w and hosting the vms deposits in the northern sector which is mostly located in spain graben basins and local pull aparts are the main structures in this sector two belts can be distinguished the deposits being located at the top of the vsc2 felsic volcanism rio tinto type ipb deposits in the central sector both in spain and portugal half graben basins are the most common structures and the deposits are mostly located in the vsc0 andesitic volcanic sedimentary sequence tharsis type ipb deposits in the southern sector which is only located in portugal a graben basin with a pull apart is again the main structure and the deposits are located in black slates and at the top of a felsic volcanism strunian in age vsc0 the deposits located in graben basin with a pull apart are essentially felsic volcanic hosted with some siliciclastic material mostly black shales by contrast those located in half graben basins are mainly hosted by black shales with minor amounts of andesitic rocks the tectonic evolution shows that as a result of a counterclockwise rotation of the stress axes the formation of the ipb and the associated ore deposits took place during several episodes from transtension with the development of both graben with pull aparts and half graben basins through left lateral e w shearing to transpression at the beginning of the transtensional process several extensional roughly e w trending faults that developed graben and half graben basins were generated and the first volcanic andesite rhyolite rocks vsc0 formed the tharsis type deposits mainly hosted by black slates with some volcanic rocks were formed in the central sector while the neves corvo type deposit hosted by black slates and felsic volcanism formed in the southern one after a period characterized by barren mafic volcanism vsc1 a sinistral shear affected the previous fractures due to the stress axis rotation and felsic crustal volcanism started vsc2 rhyolites and dacites were particularly abundant in two graben basins which developed rollovers in pull apart zones forming the rio tinto type deposits in the northern sector the thermal increase associated with vsc0 and vsc2 gave rise to the development of crustal scale hydrothermal convective cells which generated both types of deposits after a barren vsc3 felsic volcanism subsequently during the variscan transpressional phase the e w extensional faults were reactivated as reverse faults affecting the volcanic sequence vsc0 to vsc3 as well as the interbedded sedimentary rocks mostly black shales as has been recognized at the rio tinto deposit buttressing must have played a significant role in the geometry of inverted structures and the vms ores were intensely recrystallized it should be emphasized that this new regional geological model for the ipb is an approach to provide a better insight into vms deposits and could be a key point for further studies providing a new tool to improve knowledge of the vms mineralizations and exploration guidelines elsewhere in the ipb

strontium isotope geochemistry of groundwaters and streams affected by agriculture locust grove md the effects of agriculture on the isotope geochemistry of sr were investigated in two small watersheds in the atlantic coastal plain of maryland stratified shallow oxic groundwaters in both watersheds contained a retrievable record of increasing recharge rates of chemicals including no3 cl mg ca and sr that were correlated with increasing fertilizer use between about 1940 and 1990 the component of sr associated with recent agricultural recharge was relatively radiogenic 87sr 86sr 0 715 and it was overwhelming with respect to sr acquired naturally by water rock interactions in the oxidized non calcareous portion of the saturated zone agricultural groundwaters that penetrated relatively unoxidized calcareous glauconitic sediments at depth acquired an additional component of sr from dissolution of early tertiary marine caco3 87sr 86sr 0 708 while undergoing o2 reduction and denitrification ground water discharge contained mixtures of waters of various ages and redox states two streams draining the area are considered to have higher 87sr 86sr ratios and no3 concentrations than they would in the absence of agriculture however the streams have consistently different 87sr 86sr ratios and no3 concentrations because the average depth to calcareous reducing denitrifying sediments in the local groundwater flow system was different in the two watersheds the results of this study indicate that agriculture can alter significantly the isotope geochemistry of sr in aquifers and streams and that the effects could vary depending on the types sources and amounts of fertilizers added the history of fertilizer use and groundwater residence times

multi phase water rhyolite interaction and ore fluid generation at aljustrel portugal detailed study of the aljustrel volcanic rocks through petrography mineral chemistry whole rock geochemistry and previously published stable isotope data show that the rocks experienced extreme metasomatism the metasomatic phenomena presented are explained accurately by a sea water convective model the evolution of the sea water derived fluid as it progresses downwards through the rocks is evident from cold oxidising mg bearing to hot reducing mg free and enriched in si fe cu zn several lines of evidence feldspar mineralogy paragenetic relations between regional and ore zone alteration and stable isotope data show that the temperature of the hydrothermal circulation increased through time and that the water to rock ratio evolved from very high to low values according to our data about 30 ppm cu and some 100 ppm zn were removed from the aljustrel volcanics this implies for both metals the same amount of leached rock to produce the 2 mt cu and 6 mt zn contained in the massive sulphide deposits of the aljustrel area with regard to fe about 1 was on average removed from the rocks producing enough metal to account for all the fe in the ms deposits and overlying chemical sediments this study documents semi quantitatively the provenance of the main metals in major massive sulphide deposits via sea water leaching of the immediate host rocks

type of volcanoes hosting the massive sulfide deposits of the iberian pyrite belt the volcanic sedimentary complex vsc of the iberian pyrite belt ipb in southern portugal and spain comprises an upper devonian to lower carboniferous submarine succession with a variety of felsic volcanic lithofacies the architecture of the felsic volcanic centres includes felsic lavas domes pyroclastic units intrusions and minor mafic units that define lava cryptodome pumice cone volcanoes the diversity of volcanic lithofacies recognized in different areas of the ipb mainly reflects variations in proximity to source but also differences in the eruption style the ipb volcanoes are intrabasinal range in length from 2 km to 8 km and their thickest sections vary from 400 m to 800 m these volcanoes are dominated by felsic lavas domes that occur at several stratigraphic positions within the volcanic centre however the pyroclastic units are also abundant and are spatially related to the lavas domes the intrusions are minor and define cryptodomes and partly extrusive cryptodomes the hydrothermal systems that formed the neves corvo and lousal massive sulfide ore deposits are associated with effusive units of felsic volcanic centres at neves corvo the massive sulfide orebodies are associated to rhyolitic lavas that overlie relatively thick fiamme rich pyroclastic unit in several other locations within the belt pyroclastic units contain sulfide clasts that may have been derived from yet to be discovered coeval massive sulfide deposits at or below the sea floor which enhances the exploration potential of these pyroclastic units and demonstrates the need for volcanic facies analysis in exploration

chronology and climatic implications of late quaternary glaciations in the goriganga valley central himalaya india abstract goriganga valley which is located in the transition zone between the dry steppe of the tibetan plateau in the north and the sub humid himalayan climate in the south has preserved four events of glaciation with decreasing magnitude the oldest stage i glaciation is represented by a 12 5 km long discontinuous diamictite ridge which terminates north of rilkot 3100 m asl the stage ii glaciation is represented by sub rounded and partially eroded lateral moraines and terminates around martoli village 3240 m asl the stage iii and iv glacial moraines are sharp crested unstable and terminate proximal to the present day glacier at 3640 m asl and 3740 m asl respectively the stage ii moraines have been optically dated between 25 2 ka and 22 1 ka implying that glacier expanded during the global last glacial maximum lgm this is contrary to the suggestion that during last glacial maximum lgm glaciation was limited in extent due to weak indian summer monsoon ism in the monsoon dominated regions of the himalaya we ascribe the lgm glaciations to a combination of the lowered temperature and enhanced mid latitude westerlies following the lgm glaciation goriganga valley experienced two major pulses of deglaciation the older event is dated between 16 and 12 ka and is coeval with the initiation of the ism whereas the younger events 10 8 ka represent the early to mid holocene strengthened ism the stage iii and iv glaciations which terminated proximal to the modern glacier are speculated to occur during the mid holocene and little ice age lia respectively

late pleistocene glacial equilibrium line altitudes in the colorado front range a comparison of methods abstract six methods for approximating late pleistocene pinedale equilibrium line altitudes elas are compared for rapidity of data collection and error rmse from first order trend surfaces using the colorado front range trend surfaces computed from rapidly applied techniques such as glaciation threshold median altitude of small reconstructed glaciers and altitude of lowest cirque floors have relatively high rmses 97 186 m because they are subjectively derived and are based on small glaciers sensitive to microclimatic variability surfaces computed for accumulation area ratios aars and toe to headwall altitude ratios thars of large reconstructed glaciers show that an aar of 0 65 and a thar of 0 40 have the lowest rmses about 80 m and provide the same mean ela estimate about 3160 m as that of the more subjectively derived maximum altitudes of pinedale lateral moraines rmse 149 m second order trend surfaces demonstrate low elas in the latitudinal center of the front range perhaps due to higher winter accumulation there the mountains do not presently reach the ela for large glaciers and small front range cirque glaciers are not comparable to small glaciers existing during pinedale time therefore pleistocene ela depression and consequent temperature depression cannot reliably be ascertained from the calculated ela surfaces

climate impact of late quaternary equatorial pacific sea surface temperature variations magnesium calcium data from planktonic foraminifera in equatorial pacific sediment cores demonstrate that tropical pacific sea surface temperatures ssts were 2 8 0 7 c colder than the present at the last glacial maximum glacial interglacial temperature differences as great as 5 c are observed over the last 450 thousand years changes in sst coincide with changes in antarctic air temperature and precede changes in continental ice volume by about 3 thousand years suggesting that tropical cooling played a major role in driving ice age climate comparison of sst estimates from eastern and western sites indicates that the equatorial pacific zonal sst gradient was similar or somewhat larger during glacial episodes extraction of a salinity proxy from the magnesium calcium and oxygen isotope data indicates that transport of water vapor into the western pacific was enhanced during glacial episodes

reconstruction of equilibrium line altitudes for tropical and sub tropical glaciers past fluctuations of tropical and sub tropical glaciers provide important palaeoclimate proxies for regions where other forms of evidence are rare however published equilibrium line altitude ela estimates for tropical and sub tropical glaciers at the lgm vary widely reflecting the diversity of methods and approaches employed by different research groups this complicates regional and global comparisons of ela estimates and emphasises the need for standardised methods the distinctive character of tropical and sub tropical glaciers however means that standard methods for reconstructing former glacier limits elas and palaeoclimate need to be adapted for local conditions many methods of ela reconstruction explicitly or implicitly make assumptions about glacier mass balance gradients and care needs to be taken that the choice of accumulation area ratios aars balance ratios brs and terminus to head ratios thars is appropriate as such indices are influenced by climatic regime debris cover and other factors ela reconstructions should employ multiple methods and should be cross checked and fully reported to allow assessment of the accuracy of ela estimates reliable glacier chronologies are equally important dating should be based on multiple radiometric techniques wherever possible and method of dating the type of material dated and the context of the date must all be reported

the geographic distribution of strontium isotopes in danish surface waters a base for provenance studies in archaeology hydrology and agriculture abstract in this paper sr isotope signatures are reported for 192 surface water lakes ponds and rivers creeks samples from within denmark and an isotope distribution map is presented that may serve as a base for provenance applications including archaeological migration studies ground water surface water seawater interaction contamination monitoring and potentially for agricultural applications including cases of authenticity proof for particular food products the sr isotopic compositions of surface waters range from 87sr 86sr 0 7078 to 0 7125 average 0 7096 0 0016 2 this average value lies above the range of 87sr 86sr values between 0 7078 and 0 7082 expected from late cretaceous to early tertiary oligocene limestones which form the dominant bedrock type in a nw se trending belt in denmark the elevated 87sr 86sr signatures 0 7095 are explained by additions to the surface waters of radiogenic sr predominantly derived from the near surface weathering and wash out of quarternary glaciogenic tills and soils deposited and formed during and after the last two ice age stages saale and weichsel the sr isotopic compositions and concentrations of the surface waters can therefore best be modeled by a two component mixing involving carbonaceous bedrock and glaciogenic cover sediments as the two predominant sr sources a feasibility study for using sr isotopic compositions of surface waters as a proxy for bio available sr signatures was conducted in a representative test area on zealand land of legends lejre where there is no use and application of commercial fertilizers it is demonstrated that the sr isotopic signatures of lake waters from within this area are slightly higher but statistically still indistinguishable from the average value defined by snail shells and soil leachates considered to characterize the true bio available sr in combination with results from other studies this is interpreted to reflect the wash out of sr with a higher 87sr 86sr signature released by weathering in the topsoils into the saturated water tables a component which is consequently not readily transferred into the shallow rooting plants and into small herbivores feeding on them since drinking water is a likely important source of sr uptake of humans and larger animals the contention is that a surface water isotopic composition can potentially characterize the bio available component relevant for human and carnivorous large animals spline functions and ordinary linear kriging were used for modeling the geographic distribution of bio available sr isotopes over territorial denmark as expected based on the two source mixing scenario the water 87sr 86sr ratio contour maps with some notable exceptions neither mirror the pre quarternary bedrock geology nor a pleistocene soil type distribution map of denmark as a conservative suggestion the use of the average 87sr 86sr ratio of 0 7096 0 0015 2 is recommended as an average for bio available sr from within denmark bornholm excluded for human and larger animals and as a confidence band for distinguishing local from non local signatures in archaeological provenance studies the study also reveals that the average 87sr 86sr ratio of 0 7088 defined from soil extracts and small herbivores lies approximately 0 15 lower than that defined by the surface waters the authors recommend using this lower value as a local non local discriminator for food and plant authenticity control in agricultural applications

tropical snowline changes at the last glacial maximum a global assessment snowline reconstructions from the tropics and subtropics 33 s 33 n at the last glacial maximum lgm have been extracted from a new database which provides information on glacier equilibrium line altitudes elas for over 350 glacier valley localities during the late quaternary about 60 of the intra regional variability observed change in ela ela between the lgm and today is related to headwall altitude reflecting the influence of basin morphometry e g catchment size glacier slope on the response to climate change glacier valley aspect which influences the local patterns of radiation and precipitation also causes intra regional variability in ela although this influence varies greatly between regions overall reconstructed elas are smallest in the himalayas relatively small in the southern central andes and east africa and largest in the northern andes mexico and papua new guinea estimates of the temperature change implied by the range of ela within any one region calculated using the cru 10 modern climate database are consistent with high altitude temperature changes projected from reconstructions of temperature changes at lower altitude sites based in vegetation and geochemical data in the 21 ka tropics data set farrera et al 1999 climate dynamics 15 823 856

sulfate and strontium water source identification by o s and sr isotopes and their temporal changes 1997 2008 in the region of freiberg central eastern germany abstract various waters bulk atmospheric precipitation groundwater river water flowing mine water mine drainage galleries and flooding mine water were studied in the region of freiberg to achieve an improved understanding of sources and mixing processes in the hydrological cycle and to specify the main sources that determine the isotope composition of dissolved sulfate and strontium 18 o so 4 34 s so 4 and 87 sr 86 sr in river water the combined use of isotope and chemical data led to identification of three major sulfate sources i sulfate from groundwater ii sulfate from the oxidation of local ore sulfides that remained in unflooded und flooded parts after mine decommissioning and iii industrial sulfate released from abundant waste slag and tailing deposits left behind after a long mining and industrial history of the region the same three components groundwater pore water from oxidation of residual ores and industry source were identified by analyzing sr isotope ratios however the sr isotopes pointed out a fourth yet unrecognized source that contributed to water of the flooded mine section the data show that the isotope composition of water of the river freiberger mulde was mainly determined by uncontaminated groundwater diluted with atmospheric precipitation whereas the other two end members played only a minor role for this river water however for the river triebisch the isotope compositions of dissolved sulfate and strontium record a strong impact of end members ii and iii after recharging the flooding water into the river a twelve year monitoring 1997 2008 revealed a strong decrease of 18 o so 4 values of water from bulk atmospheric precipitation as of 2006 2008 7 compared to 1997 14 while 34 s so 4 values remained constant 5 this isotope shift was probably caused by a lower contribution of primary sulfates to atmospheric precipitation in recent years groundwater and river water freiberger mulde also showed decreasing 18 o so 4 values albeit to a lower degree by 4 5 a decrease of 18 o so 4 values was again found in flowing mine water by 5 6 mainly affected by end member i uncontaminated groundwater the flood event in august 2002 likely washed out large parts of older groundwater and thus enabled the relatively large oxygen isotope decrease 18 o so 4 of groundwater and river water within a few years the previously high input from the industrial source waste and slag deposits decreased from 1997 to 2002 in some drainage galleries and flooding water that discharge their water into local rivers this led to lower 18 o and 34 s values of dissolved sulfates in these waters accompanied by a concentration decrease of several elements cl na and mg however no further decrease of the impact of this source could be detected after the storm and flood event in august 2002

comparing reconstructed pleistocene equilibrium line altitudes in the tropical andes of central peru glacier equilibrium line altitude ela and the difference between modern and palaeo ela can be interpreted as a proxy for climate change one issue in ela reconstruction is that different methods of ela reconstruction may produce a range of results for the same palaeoglacier when a range of methods is used to reconstruct elas across a region resulting variations may be related to the method rather than the past climate palaeoclimatic interpretation of elas that were reconstructed by different methods may prompt spurious inferences if the ela range is the result of methodological differences rather than climatic variation we address the relationship and degree of variation between methods by comparing terminus to headwall altitude ratio thar accumulation area ratio aar and accumulation area balance ratio aabr methods for palaeoglaciers in four valleys in the tropical andes valleys in the eastern cordillera of the peruvian andes bordering the junin plain 11 s 76 w ca 4100 m a s l are presently ice free but were glaciated repeatedly during the pleistocene we use a combination of 90 m shuttle radar topography mission srtm data 15 m advanced spaceborne thermal emission and reflection radiometer aster data and 1 25 000 topographic maps to reconstruct elas within each of three groups of moraines map based thar and aabr estimates of ela tend to be highest followed by dem derived thar elas with aar reconstructed elas somewhat lower in this region ela estimates for the local last glacial max imum llgm range from ca 4250 to 4570 m a s l with elas of ca 220 to 550 m depending on valley and method used within individual valleys elas for the same palaeoglaciers calculated by different methods vary by 100 m elas of the llgm glaciers and those of the largest glaciers to occupy the junin valleys 65 ka are not markedly different from each other regardless of the method used in their calculation which is largely a reflection of the valley hypsometry in the region our analysis suggests relatively low decreases in temperature during glacial periods in the region ca 2 5 1 c copyright 2005 john wiley sons ltd

mass balance and equilibrium line altitudes of glaciers in high mountain environments abstract the mass balance characteristics of glaciers in high mountain environments complicate the relationship between glacier equilibrium line altitudes elas and climatic variables such as precipitation and air temperature therefore methods of ela reconstruction employed in low relief environments are commonly not applicable in high mountains or require some modification we review the concept of the ela with reference to the mass balance of a range of glacier types found in high mountain regions we examine the applicability of several commonly used methods of ela reconstruction for different glacier types and propose some general principles to guide the choice of appropriate methods

millennial scale record of landslides in the andes consistent with earthquake trigger landslide deposits are often interpreted as the consequence of precipitation a millennial scale record of landslides inferred from river cobbles in the arid andes is instead consistent with earthquake triggering

timing and extent of holocene glaciations in the monsoon dominated dunagiri valley bangni glacier central himalaya india abstract field stratigraphy and optical and radiocarbon dating of lateral moraines in the monsoon dominated dunagiri valley of the central himalaya provide evidence for three major glaciations during the last 12 ka the oldest and most extensive glaciation the bangni glacial stage i bgs i is dated between 12 and 9 ka followed by the bgs ii glaciation 7 5 and 4 5 ka and the bgs iii glaciation 1 ka in addition discrete moraine mounds proximal to the present day glacier snout are attributed to the little ice age lia bgs i started around the younger dryas yd cooling event and persisted till the early holocene when the indian summer monsoon ism strengthened the less extensive bgs ii glaciation which occurred during the early to mid holocene is ascribed to lower temperature and decreased precipitation further reduction in ice volume during bgs iii is attributed to a late holocene warm and moist climate although the glaciers respond to a combination of temperature and precipitation changes in the dunagiri valley decreased temperature seems to be the major driver of glaciations during the holocene

evolution of late cretaceous and early tertiary basins of southwest utah based on clastic petrology abstract upper cretaceous to eocene clastic rocks of southwest utah record active sevier style thrust deformation cessation of thrusting and sedimentation related to laramide style folding the formations which record these tectonic events include from oldest to youngest the iron springs kaiparowits canaan peak grapevine wash grand castle informal name pine hollow and claron formations two petrographically distinct upward coarsening petrofacies occur in the foreland basin and are herein named for the formations they comprise the kaiparowits canaan peak and iron springs grand castle petrofacies the kaiparowits canaan peak petrofacies consists of volcanic and radiolarian chert lithic fragments derived from sources in southeastern california and southern nevada the finer grained kaiparowits formation was deposited during active thrusting in the middle to upper campanian while the conglomeratic canaan peak formation was deposited during cessation of thrust activity between the upper campanian and lower paleocene the iron springs grand castle petrofacies contains quartzite and carbonate clasts and sandstone compositions that suggest derivation from the wah wah and blue mountain thrust sheets in southwestern utah the iron springs formation represents upper cretaceous syn thrusting deposition whereas the grand castle conglomerates were deposited during lower paleocene rebound of these thrust sheets the upper cretaceous to paleocene grapevine wash formation is an areally restricted conglomeratic alluvial fan sequence composed of carbonate and sandstone clasts derived from paleozoic rocks in the upper plate of the square top mountain thrust in southwestern utah the pine hollow formation received sediment during development of laramide style folding of the sevier foreland basin during early paleocene to middle eocene time jurassic and cretaceous sedimentary units tilted during deformation shed detritus to the east and southwest into an intermontane basin the clastic basal part of the claron formation paleocene to eocene also received sediment from exposed highlands related to laramide structures the abundance of silty carbonate lithic grains suggests that much of the sedimentation in the claron basin was intraformational

kinetic and mineralogic controls on the evolution of groundwater chemistry and 87sr 86sr in a sandy silicate aquifer northern wisconsin usa abstract substantial flowpath related variability of 87sr 86sr is observed in groundwaters collected from the trout lake watershed of northern wisconsin in the extensive shallow aquifer composed of sandy glacial outwash groundwater is recharged either by seepage from lakes or by precipitation that infiltrates the inter lake uplands 87sr 86sr of groundwater derived mainly as seepage from a precipitation dominated lake near the head of the watershed decreases with progressive water chemical evolution along its flowpath due primarily to enhanced dissolution of relatively unradiogenic plagioclase in contrast 87sr 86sr of groundwater derived mainly from precipitation that infiltrates upland areas is substantially greater than that of precipitation collected from the watershed due to suppression of plagioclase dissolution together with preferential leaching of sr from radiogenic phases such as k feldspar and biotite the results of a column experiment that simulated the effects of changing residence time of water in the aquifer sand indicate that mobile waters obtain relatively unradiogenic sr whereas stagnant waters obtain relatively radiogenic sr nearly the entire range of strontium isotope composition observed in groundwaters from the watershed was measured in the experimental product waters the constant mobility of water along groundwater recharge flowpaths emanating from the lakes promotes the dissolution of relatively unradiogenic plagioclase perhaps due to effective dispersal of clay mineral nuclei resulting from dissolution reactions in contrast episodic stagnation in the unsaturated zone along the upland recharge flowpaths suppresses plagioclase dissolution perhaps due to accumulation of clay mineral nuclei on its reactive surfaces differences in redox conditions along these contrasting flowpaths probably enhance the observed differences in strontium isotope behavior this study demonstrates that factors other than the calculated state of mineral saturation must be considered when attempting to simulate chemical evolution along flowpaths and that reaction models must be able to incorporate changing contributions from reacting minerals in the calculations

terrestrial conditions at the last glacial maximum and climap sea surface temperature estimates are they consistent climap 1981 seasonal reconstruction of the earth s surface at the last glacial maximum geological society of america map and chart series mc 36 boundary conditions were used as inputs to the giss general circulation model and the last glacial maximum lgm climate was simulated for six model years the simulation was compared with snow line depression and pollen inferred temperature data at low latitudes specifically for hawaii colombia east africa and new guinea the model does not produced as much cooling at low latitudes as is implied by the terrestrial evidence an alternative experiment in which the climap sea surface temperatures were uniformly lowered by 2 c produces a better fit to the land data although in hawaii model temperatures are still too warm the relatively warm climap tropical sea surface temperatures also provide for only a slight decrease in the hydrologic cycle in the model in contrast to both evidence of lgm tropical aridity and the results of the experiment with colder ocean temperatures with the climap sea surface temperatures the lgm global annual mean surface air temperature is 3 6 c colder than at present if the ocean temperatures were allowed to cool in conformity with the model s radiation balance the lgm simulation would be 5 6 c colder than today and in better agreement with the tropical land evidence

regional synthesis of last glacial maximum snowlines in the tropical andes south america the modern glaciers of the tropical andes are a small remnant of the ice that occupied the mountain chain during past glacial periods estimates of local last glacial maximum lgm snowline depression range from low e g 200 300 m in the junin region peru through intermediate 600 m at laguna kollpa kkota in bolivia to high e g 1100 1350 m in the cordillera oriental peru although a considerable body of work on paleosnowlines exists for the tropical andes absolute dating is lacking for most sites moraines that have been reliably dated to 21 cal kyr bp have been identified at few locations in the tropical andes more commonly but still rarely moraines can be bracketed between about 10 14 c kyr 11 5 cal kyr bp and 30 14 c kyr bp typically only minimum limiting ages for glacial retreat are available cosmogenic dating of erratics on moraines may be able to provide absolute dating with sufficient accuracy to identify deposits of the local lgm ongoing work using cosmogenic 10 be and 26 al in peru and bolivia suggests that the local lgm may have occurred prior to 21 cal kyr bp r 2005 elsevier ltd and inqua all rights reserved

the use of hypsometry to indicate long term stability and response of valley glaciers to changes in mass transfer a simple equation is derived relating the net mass balance and hypsometric curves of a steady state valley glacier it is used to examine how valley shape is linked to disparate extents and responses of glaciers subjected to similar climatic conditions examples are given which show that area based indices e g aar for estimating the equilibrium line altitude ela may be subject to a substantial built in variance because they implicitly rely upon similarity of glacier shape and regimen over a region if accurate topographic maps are available the equation may be used to infer the regimen of modern glaciers in the form of a dimensionless ratio of net mass balance gradients alternatively if similar information is available concerning regional glacier regimen disparate extents and responses may be collectively utilized to estimate values of ela or to infer climatic influence taking glacier hypsometry into account

late quaternary glaciation of the cordillera real bolivia glacial geological studies in tropical mountain areas of the southern hemisphere can be used to address two issues of late pleistocene climate change the global synchroneity of deglaciation and the magnitude of temperature reduction in the tropics radiocarbon dates from the cordillera real and from other areas in peru and bolivia suggest that late pleistocene glaciation culminated between 14 000 and 12 000 yr bp followed by rapid deglaciation because deglaciation was apparently synchronous with that in northern hemisphere regions insolation change at high latitudes may not have been the only factor that produced global deglaciation at this time late pleistocene glaciation in the cordillera real culminated when precipitation was 200 mm yr 1 higher and temperatures were 3 5 1 6 c lower than today this produced an equilibrium line altitude depression of about 300 100 m on the western side of the cordillera prior to this conditions were drier and probably at least as cold however the lack of moraines in the cordillera real dated to the last glacial maximum ca 18000 yr bp precludes using the equilibrium line altitude method to quantitatively evaluate the discrepancy between warm sea surface temperatures and cold terrestrial conditions reconstructed with other proxies for this time period

early local last glacial maximum in the tropical andes the local last glacial maximum in the tropical andes was earlier and less extensive than previously thought based on 106 cosmogenic ages from beryllium 10 dating from moraines in peru and bolivia glaciers reached their greatest extent in the last glacial cycle 34 000 years before the present and were retreating by 21 000 years before the present implying that tropical controls on ice volumes were asynchronous with those in the northern hemisphere our estimates of snowline depression reflect about half the temperature change indicated by previous widely cited figures which helps resolve the discrepancy between estimates of terrestrial and marine temperature depression during the last glacial cycle

interaction between different water bodies in a small catchment in the paris basin brevilles france tracing of multiple sr sources through sr isotopes coupled with mg sr and ca sr ratios abstract intensive monitoring of the cuise sands aquifer in a small agricultural catchment 3 km2 where agricultural practices are well documented over nearly 5 a showed significant disparities for major element concentrations sr concentrations isotopic compositions and 3h values depending on the groundwater sampling locations lower 87sr 86sr values 0 7079 0 7085 associated with low no 3 concentrations low mg sr molar ratios 0 7085 and higher mg sr molar ratios 250 suggest a contribution of sr from anthropogenic sources strontium isotopes coupled with mg sr and ca sr ratios of groundwater in this catchment successfully demonstrated the capacity to trace fertilizer contributions which significantly modify the natural sr isotopic signature of groundwater the specific geochemical signature of groundwater revealed by sr isotopes in addition to major and trace element concentrations in particular mg sr and ca sr molar ratios demonstrated the partial isolation of groundwater bodies in this catchment compartmentalisation of the aquifer is compatible with fault distribution as defined by geological and geophysical investigations thus the sr isotopic tool coupled with mg sr and ca sr ratios has been applied with success to trace water pathways and recharge and to provide scenarios for the hydrological functioning of the system

debris covered glaciers in the sierra nevada california and their implications for snowline reconstructions abstract ice walled melt ponds on the surfaces of active valley floor rock glaciers and matthes little ice age moraines in the southern sierra nevada indicate that most of these landforms consist of glacier ice under thin ca 1 10 m but continuous covers of rock fall generated debris these debris blankets effectively insulate the underlying ice and greatly reduce rates of ablation relative to that of uncovered ice such insulation explains the observations that ice cored rock glaciers in the sierra actually debris covered glaciers are apparently less sensitive to climatic warming and commonly advance to lower altitudes than do adjacent bare ice glaciers accumulation area ratios and toe to headwall altitude ratios used to estimate equilibrium line altitudes elas of former glaciers may therefore yield incorrect results for cirque glaciers subject to abundant rockfall inadvertent lumping of deposits from former debris covered and bare ice glaciers partially explains an apparently anomalous regional ela gradient reported for the pre matthes recess peak neoglacial advance distinguishing such deposits may be important to studies that rely on paleo ela estimates moreover matthes and recess peak ela gradients along the crest evidently depend strongly on local orographic effects rather than latitudinal climatic trends indicating that simple linear projections and regional climatic interpretations of ela gradients of small glaciers may be unreliable

magmatic evolution and tectonic setting of the iberian pyrite belt volcanism rocks has been carried out to determine the primary magmatic aynity tectonics iberian pyrite belt and tectonic setting of the iberian pyrite belt volcanism most of the basaltic rocks are continental tholeiites but a few samples show an alkaline aynity the origin of the basaltic rocks and their diversity of compositions are explained by a single mixing model between e and n morb mid ocean ridge basalt and as introduction similation of crustal material calc alkaline intermediate and silicic volcanic hosted massive sulphide deposits are mainly rocks include basaltic andesites andesites dacites and rhyolites associated world wide with calc alkaline submarine volvolumetrically dacites and rhyolites are the most abundant inter canism petrological and geochemical data together with mediate and silicic rocks are not related by fractional crystallization stratigraphic and structural studies have been of major nor is there a relationship between the basaltic and calc alkaline importance in constraining geological models of the volrocks by the same process we suggest that in the iberian pyrite canism associated with massive sulphide deposits inbelt silicic calc alkaline magmas were generated on a large scale tegrated studies in areas such as the kuroko province in by the invasion of continental crust by mafic magmas generated in japan ohmoto 1983 the mount read volcanics in the underlying upper mantle the diversity of compositions shown tasmania crawford et al 1992 and the mount windsor by dacites and rhyolites can mainly be explained either by diverences volcanics in northwestern australia stolz 1995 have in the composition of the source rocks or by diverent degrees of revealed that this volcanism may be developed during partial melting of upper crust rocks andesites however formed by diverent stages of the subduction process always being mixing between basaltic magmas and upper crust material the new located on the overriding plate geochemical data agree with previously published tectonostratigraphic this paper documents the petrology and geochemistry data which suggest that the iberian pyrite belt volcanism formed of the volcanism of the iberian pyrite belt an early on the south portuguese plate owing to strike slip tectonics this carboniferous metallogenic province that extends from portugal to spain in southwest iberia and constitutes local extensional tectonic setting was related to transtension as a