a synthesis of lead isotopes in two millennia of european air four airborne particulate records from ombrotrophic peat bogs in southern norway extending back 300 years have been measured for chronology lead concentration and lead isotope composition since southern norway receives an airborne lead signal that accumulates emissions from the european continent the trend in the four bog records can be used to correlate previously reported measurements from france switzerland england and greenland that cover different ranges of time when these are compiled the integrated european record that emerges spans the last 2300 years of human influence on lead in the air over europe and suggests human control of lead in airborne particulates over the entire period from 366 bc through the first half of the 20th century lead isotopic compositions in european air have fallen within the range of compositions in european ore bodies since 1950 isotopic compositions have been beyond the range in those ore body compositions and have fallen within the array of lead isotope compositions typical of gasoline from western industrial nations a mixing line between us and australian lead in gasoline the overlap between the european record and the range in modern european air suggests an average isotopic composition of 206 pb 207 pb ca 1 13 and of 208p b 207 pb ca 2 41 in air over europe during the last 20 years 1999 elsevier science b v all rights reserved

comment on the biosphere a homogeniser of pb isotope signals by c reimann b flem a arnoldussen p englmaier t e finne f koller and o nordgulen

evidence from earthquake data for a partially molten crustal layer in southern tibet earthquake data collected by the indepth ii passive source experiment show that there is a substantial south to north variation in the velocity structure of the crust beneath southern tibet north of the zangbo suture beneath the southern lhasa block a midcrustal low velocity zone is revealed by inversion of receiver functions rayleigh wave phase velocities and modeling of the radial component of teleseismic p waveforms conversely to the south beneath the tethyan himalaya no low velocity zone was observed the presence of the midcrustal low velocity zone in the north implies that a partially molten layer is in the middle crust beneath the northern yadong gulu rift and possibly much of southern tibet

tectonic significance of paleobotanically estimated climate and altitude of the late eocene erosion surface colorado erosion beveled the laramide front range uplift in colorado to a surface of low relief by the end of the eocene this study uses j a wolfe s new multivariate climate analysis techniques to determine the paleoelevation of this regional surface by examining the overlying 35 ma florissant flora a multiple regression model explaining 93 3 of the variance in mean annual temperature was developed using wolfe s dataset of 31 leaf physiognomic character states for 86 modern vegetation sites these character states were scored on 29 species collected from one facies of the florissant lake beds the paleotemperature estimate of mean annual temperature 10 7 plus minus 1 5c derived from these data when combined with sea level temperature and terrestrial lapse rate implies a late eocene paleoelevation of 2 4 2 7 km pliocene uplift is thus not required to explain the present elevation of 2 5 km it is unclear when and why the southern rocky mountains achieved this elevation magmatic crustal thickening can explain the late eocene high elevation of the southern rockies but neither this mechanism nor compressive thickening explains why the great plains which are tied to the florissant elevation by the wall mountain tuff were also high this paleoelevation estimate indicates that regional surfacesmore of planation could be formed at high elevation in the eocene probably because of peculiarities of the eocene climate less

mineralogy and the release of trace elements from slag from the hegeler zinc smelter illinois usa abstract slag from the former hegeler zn smelting facility in illinois usa is mainly composed of spinifex ca rich plagioclase fine grained dendritic or coarse grained subhedral to anhedral clinopyroxenes euhedral to subhedral spinels spherical blebs of fe sulfides silicate glass and less commonly fayalitic olivine mullite and quartz were also identified in one sample as representing remnants of the furnace lining secondary phases such as goethite hematite and gypsum are significant in some samples and reflect surficial weathering of the dump piles or represent byproducts of roasting a relatively rare zn rich material contains anhedral willemite subhedral gahnite massive zincite hardystonite and a zn sulfate brianyoungite among other phases and likely represents the molten content of the smelting furnace before zn extraction the bulk major element chemistry of most slag samples is dominated by sio2 al2o3 fe2o3 and cao the bulk composition of the slag suggests a high viscosity of the melt and the mineralogy suggests a high silica content of the melt bulk slag trace element chemistry shows that the dominant metal is zn with 28 4 wt in the zn rich material and between 212 and 14 900 mg kg in the other slags the concentrations of other trace elements reach the following 45 mg kg as 1170 mg kg ba 191 mg kg cd 242 mg kg co 103 mg kg cr 6360 mg kg cu 107 mg kg ni and 711 mg kg pb zinc as the dominant metal in the slags is likely the most environmentally significant metal in these samples cd cu and pb are also of concern and their concentrations exceed us environmental protection agency preliminary remediation goals for residential soils spinel was found to be the dominant concentrator of zn for samples containing significant zn 1 wt the silicate glass also contained relatively high concentrations of zn compared to other phases zinc partitioned into the silicates and oxides in these samples is generally more resistant to weathering and therefore less leached when compared to the slag samples with lower bulk zn concentrations where zn is likely partitioned into volumetrically minor sulfides this is confirmed by leachate tests that resulted in low leachate zn concentrations for samples with zn partitioned into spinel in contrast the concentrations of zn and so4 are close to those expected from the dissolution of stoichiometric zns in leachates from samples in which the dominant host of zn is suspected to be sulfides the fact that zn and other metals occur commonly as sulfides which are more reactive than the silicates and oxides into which they dominantly partition according to other slag studies indicates the hegeler slag pile may be more of an environmental concern than other slag piles

structural elements of the southern tethyan himalaya crust from wide angle seismic data a deep seismic common midpoint cmp profile shot across the southern margin of the tethyan himalaya as the first stage of project international deep profiling of tibet and the himalaya indepth imaged the top main himalayan thrust or mht and bottom moho of the indian continental crust underthrusting the himalaya we used portable seismographs to record the cmp profile shots at a wide range of offsets up to 155 km our short offset data corroborate the cmp profile data while our large offset data are dominated by a band of reflectivity we interpret the bright onset of this reflective band as the basal detachment of the south tibetan detachment system and a phase at the end of the reflective band as the mht we used the cmp profile first break data to model the uppermost 2 km in detail the depth of young extensional basins of the yadong rift system along the cmp profile was constrained to a maximum of 2 km yielding a throw of 4 6 km across the eastern flank of the rift and a rough estimate of approximately 1 5 east west extension by normal faulting in the tethyan himalaya the wide angle data were used to construct a crustal seismic velocity model down to the mht the south tibetan detachment system stds basal detachment reflector is observed dipping 12 5 nne from a depth of about 6 km beneath the surface under the south end of the cmp profile to a depth of 22 km then flattening to a dip of only 2 5 nne thus our observations suggest that the stds basal detachment is a deep rooted basement fault for the mht we observe a dip of 7 5 nne from 20 km depth below sea level at the crest of the high himalaya crystalline sheet to 36 km below sea level 40 km beneath the surface at a distance of about 70 km south of the indus yarlung suture iys from geometrical arguments we suggest that indian crust underthrusts the surface expression of the iys within the crust but does not form the lower crust of central and northern tibet

formation of alunite jarosite and hydrous iron oxides in a hypersaline system lake tyrrell victoria australia abstract alunite kal 3 so 4 2 oh 6 and jarosite kfe 3 so 4 2 oh 6 are common weathering products of aluminosilicates and pyrite long range transport of the constituents forming these minerals and the subsequent deposition of alunite and jarosite in an evaporite setting have not been previously documented such conditions for the occurrence of alunite and jarosite were investigated in a hypersaline system where acid groundwater enriched in k al fe iii and so 4 enter a saltplaya lake sediment cores were studied by thin section xrd and sem eds groundwater and pore water chemistries were also analyzed the results show that alunite and jarosite occur together or as individual layers and cements within the top 20 cm of the sediments where the groundwater is most concentrated due to evaporation hydrous fe oxides also occur as cements or vein fillings with the alunite and jarosite but are distributed throughout the 70 cm sediment column studied the results are consistent with a model in which alunite and jarosite precipitate as a result of the evaporation of water thermodynamic modeling indicates that the pore water in the playa sediments maybe in equilibrium with alunite jarosite and hydrous fe oxides

shrimp u pb zircon geochronology of the strzelin gneiss sw poland evidence for a neoproterozoic thermal event in the fore sudetic block central european variscides zircon ages recorded in gneissic rocks have recently been used as criteria to define and correlate various tectonic units and crustal blocks in the central european variscides a shrimp u pb zircon geochronological study of the strzelin gneiss in the fore sudetic block sw poland indicates the presence of 1 inherited zircon cores of palaeo to mesoproterozoic 206pb 238u ages between ca 2 000 and 1 240 ma and 2 zoned rims of neoproterozoic age with two distinct means of 600 7 and 568 7 ma the proterozoic age range of the cores suggests that different precambrian crustal elements were the source for the protolith of the gneiss a likely scenario is the erosion of various proterozoic granites and gneisses sedimentation after 1 240 ma and partial resistance of the original components to subsequent metamorphic dissolution and or anatectic resorption in neoproterozoic times the zoned zircon rims of both of the younger neoproterozoic ages are indistinguishable in the cathodoluminescence images the data are interpreted in terms of two different thermal events inducing zoned zircon overgrowth at ca 600 and 568 ma in general the new results confirm earlier assumptions of the proterozoic age of the gneiss protoliths and indicate their similarity to orthogneisses in the east sudetes tectonic domain e g the velke vrbno and desna gneisses the neoproterozoic dates are different from the age of 504 3 reported earlier for the go ciecice gneiss from a neighbouring locality in the strzelin massif the new data strongly indicate a moravo silesian bruno vistulian affinity for the strzelin gneiss and support the hypothesis that the strzelin massif lies within the tectonic boundary zone between the west and east sudetes domains which represents the northern continuation of the moldanubian thrust

a 2 d ray based depth migration method for deep seismic reflections summary although accurate depth migration is essential for the correct geometrical interpretation of deep reflection data migration by the standard numerical methods has generally not been satisfactory the alternative method presented in this paper provides an efficient migration for deep reflection profiles in the form of a digitized line drawing assuming a general 2 d velocity structure migration of a digitized line drawing reduces the effects of low signal noise ratios the calculation is rapid allowing migrations to be calculated for a large number of alternative velocity structures and iterative improvement of the velocity structure the migration has been applied to 3 d structures observed on intersecting profiles collected by birps british institutes reflection profiling syndicate

seismic imaging of the waltham canyon fault california comparison of ray theoretical and fresnel volume prestack depth migration abstract near vertical faults can be imaged using reflected refractions identified in controlled source seismic data often theses phases are observed on a few neighboring shot or receiver gathers resulting in a low fold data set imaging can be carried out with kirchhoff prestack depth migration in which migration noise is suppressed by constructive stacking of large amounts of multifold data fresnel volume migration can be used for low fold data without severe migration noise as the smearing along isochrones is limited to the first fresnel zone around the reflection point we developed a modified fresnel volume migration technique to enhance imaging of steep faults and to suppress noise and undesired coherent phases the modifications include target oriented filters to separate reflected refractions from steep dipping faults and reflections with hyperbolic moveout undesired phases like multiple reflections mode conversions direct p and s waves and surface waves are suppressed by these filters as an alternative approach we developed a new prestack line drawing migration method which can be considered as a proxy to an infinite frequency approximation of the fresnel volume migration the line drawing migration is not considering waveform information but requires significantly shorter computational time target oriented filters were extended by dip filters in the line drawing migration method the migration methods were tested with synthetic data and applied to real data from the waltham canyon fault california the two techniques are applied best in combination to design filters and to generate complementary images of steep faults

metal mobilization from base metal smelting slag dumps in sierra almagrera almeria spain abstract smelting slags associated with base metal vein deposits of the sierra almagrera area se spain show high concentrations of ag 2 0 mg l fe 0 22 9 8 mg l mn 0 85 40 2 mg l ni 0 092 2 7 mg l pb 2 0 mg l and zn 2 5 mg l and mobilization of ag 0 2 31 g l as 5 2 31 g l cd 1 3 36 8 g l and hg 0 2 7 g l the leachates were modeled using the numerical code phreeqc the results suggested the dissolution of fayalite ferrihydrite jarosite pyrrhotite goethite anglesite goslarite chalcanthite and cotunnite the presence of secondary phases in the slag dumps and contaminated soils may indicate the mobilization of metals and metalloids and help to explain the sources of groundwater contamination

long term migration of metals at historical smelting sites the vertical migration of metals in soils and rocks is assessed at 3 historical pb smelters ranging in age from ca 600 to ca 1800 a core samples were taken through contaminated soils into the underlying rocks and analysed for trace elements by icp aes surface soils contain high levels of metals particularly pb which often exceeds a concentration of 1 of the total amount of pb and zn present in contaminated soils only relatively small amounts appear to be in a readily mobile form lead concentrations in heavily contaminated horizons were too high to be controlled entirely by exchange reactions it is suggested that the metal is also present occluded in slag particles precipitated as insoluble compounds and specifically adsorbed to soil constituents the low pb mobility in soils is also related to the elevation of ph in contaminated soils by the release of ca compounds from the slag wastes during weathering the rate of vertical migration of pb varies with rock type with sandstone being greater than limestone which is greater than a clay sandstone matrix

test of climate leaf physiognomy regression models their application to two miocene floras from kenya and 40ar 39ar dating of the late miocene kapturo site abstract to test multiple regression models developed to predict seven variables of climate from leaf margin and size characters leaf character data were collected from modern woodland and rainforest plant communities in uganda these localities were chosen for their structural similarity to two fossil sites for which climate values were desired the test indicated that for these communities the model accurately predicts mean annual temperature however the multiple regression models overestimate seasonality of temperature and mean annual and seasonal precipitation amounts for the two modern communities reasons for the models inaccuracies may include no african analog in the non african database on which the model is based too much intraspecific variability in leaf size an important character in precipitation models and relationships between leaf form and climate that may not be well defined by multiple regression mean annual temperatures were reconstructed for two miocene paleobotanical localities from the tugen hills of the eastern rift valley kenya using leaf form data primarily margin characters the results indicate that mean annual temperatures at kabarsero 12 6 ma and kapturo 6 7 7 2 ma were essentially equivalent to temperatures at those localities today and differed little from one another the kapturo paleofloral assemblage is a deciduous woodland interpreted as indicating less available or more seasonal moisture than the kabarsero paleofloral assemblage a wet forest with west african floral affinities laser fusion 40 ar 39 ar dating of volcanic materials at kapturo provides the first control of this paleoflora bracketed by a 7 2 ma trachyte at the base of the sedimentary sequence and an age of 6 7 ma on a reworked tuff overlying the fossiliferous horizon the chronologic data places the paleofloral assemblage in stratigraphic context relative to other tugen hills units containing paleofloras and abundant vertebrate remains including hominoids

foliar physiognomic record of climatic conditions during dormancy climate leaf analysis multivariate program clamp and the cold month mean temperature abstract the extent to which the leaves of woody dicots encode in their physiognomy the climatic conditions that exist during dormancy was tested by sampling 20 sites along an approximately west east transect across european russia the crimean peninsula western siberia and central eastern siberia this transect encompassed the most extreme mean annual temperature range recorded in the modern world where vegetation exists climate leaf analysis multivariate program clamp revealed little change in calibration of the warm month mean temperature compared with the physg3ar data set derived from less extreme sites primarily in north america and japan but significant change with respect to the cold month mean temperature cmmt calibration although clamp underestimated the cmmt by up to 9 c in the coldest sites the addition of the transect sites improved clamp s performance at low temperatures this suggests that winter cold is encoded in foliar physiognomy even though the leaves are functional only duri

formation of sequences of cemented layers and hardpans within sulfide bearing mine tailings mine district freiberg germany abstract the roles of mineral dissolution precipitation transformation and mass transport processes related to formation of characteristic cemented layer hardpan sequences were studied in low sulfide and low carbonate freiberg polymetallic mine tailings using high resolution profiling combined geochemical geomicrobiological and geophysical methods allowed description of the process of weathering of reactive mineral phases and the position of the oxidation front in detail as well as revealing the mechanisms of cementation of tailings predominantly by the formation of gels poorly crystalline phases autochthonous and allochthonous gels reduced the porosity of cemented layers to values 1 whereas secondary crystalline phases were less efficient in filling the pore space electron microprobe analysis of cemented tailings showed that common jarosite group minerals contained up to about 8 wt pbo and 0 2 1 9 wt as 2 o 5 iron as si gels reached contents of up to 44 wt as 2 o 5 in gel rich cemented layers zinc was below the detection limit in the studied secondary phases sequential extraction of cemented and related oxidized brown silt layers confirmed that the bulk of as was bound to amorphous poorly crystalline hydrous oxides of fe whereas pb was often bound to jarosite zinc was found preferentially in the water soluble and the exchangeable fractions in the grey silt and the sand directly underlying the oxidized layers as pb and zn occurred as sulfide minerals the main effects of the cemented layer hardpan sequences at the studied site are 1 a temporary natural attenuation of the toxic compounds 2 a restriction of the downward movement of the oxidation front and 3 a reduction of the extent of the erosion of the surface of the tailings impoundment by wind and water the potential of a heap to form cemented layers and hardpans is greatly increased by a heterogeneous distribution of grain sizes and reactive materials in the topmost zone as well as by the occurrence of sulfide rich tailings on top of layers with low permeability

arsenic and metal mobility from au mine tailings in rodalquilar almeria se spain in the old mining area of rodalquilar mine wastes soil and sediments were characterized and the results revealed high concentration of au ag as bi cu fe mn pb se sb and zn in tailings and sediments the contaminant of greatest environmental concern is as the mean concentration in the tailings was 679 9 and 345 mg kg in the sediments of playazo creek the groundwater samples from the alluvial aquifer showed high concentration of al as cd fe hg mn ni pb se sb and zn and very high concentration of chloride and sulfate which were above the concentration defined in the european standards for drinking water the presence of as in groundwater may be caused by the oxidation of arsenian pyrite the possible as desorption from goethite and ferrihydrite and the jarosite dissolution groundwater concentrations of cd fe mn and possibly cu were associated with low values of eh indicating the possible dissolution of oxy hydroxides of fe and mn the mobility of metals in the column experiments show the release of al fe mn cr cu ni v and zn in significant concentrations but below the detected values in groundwater however as cd sb se pb and au are generally mobilized in concentrations above the detected values in groundwater the possible mass transfer processes that could explain the presence of the contaminants in the aquifer and the leachates was simulated with the phreeqc numerical code and revealed the possible dissolution of the following mineral phases jarosite natrojarosite arsenian pyrite alunite chlorite kaolinite and calcite

extensive weathering of zinc smelting slag in a heap in upper silesia poland potential environmental risks posed by mechanical disturbance of slag deposits abstract slags from base metal smelting are often deposited for over 100 years with no barriers between the heap and the surrounding environment observations at the external surfaces of the slag heaps may not reflect the state of the slag material inside the slag heap a slag heap from zn pb ore smelting wietochlowice upper silesia poland was disturbed during recent slag removal and the freshly uncovered surfaces are examined in this study the material forming the interior of the slag heap is fine grained up to 5 cm and strongly weathered called the weathered slag zone in contrast to the large slag boulders on the surface of the slag heap up to 2 m which are only slightly weathered the weathered slag zone is composed of gypsum and hematite plus a mixture of primary and other secondary phases the weathered material as a whole is chemically more homogenous than unweathered slags and has lower si and higher fe pb up to 3 wt and cd up to 560 mg kg concentrations sem images show that primary slag phases are porous and disintegrated the examined surfaces are 3 4 m high and 10 30 m wide suggesting that such slag weathering may have occurred in more extensive parts of the slag heap weathering affects slag types with different phase compositions and is therefore controlled by specific conditions occurring within the heap not by the type of slag these conditions are so far not well defined but may include prolonged slag deposition slow water transfer within the heap and interaction of slags with acid rains common in the upper silesia region the weathered slag zone when confined within the slag heap acts as a sink for many potentially toxic elements decreasing their release to the environment however this may change dramatically when the zone is uncovered and its deposit conditions change potential risks encompass release of potentially toxic elements from the heap transport of fine grained particles to the surrounding environment and release of elements when the material is deposited in nearby soils or waters as well as when it is reused as a construction material

mineral precipitation and dissolution at two slag disposal sites in northwestern indiana usa slag is a ubiquitous byproduct of the iron and steel refining industries in northwestern indiana and northeastern illinois slag has been deposited over more than 52 km2 of land surface despite the widespread use of slag for fill and construction purposes little is known about its chemical effects on the environment two slag disposal sites were examined in northwestern indiana where slag was deposited over the native glacial deposits at a third site where slag was not present background conditions were defined samples were collected from cores and drill cuttings and described with scanning electron microscopy and electron microprobe analysis ground water samples were collected and used to assess thermodynamic equilibria between authigenic minerals and existing conditions differences in the mineralogy at background and slag affected sites were apparent calcite dolomite gypsum iron oxides and clay minerals were abundant in native sediments immediately beneath the slag mineral features indicated that these minerals precipitated rapidly from slag drainage and co precipitated minor amounts of non calcium metals and trace elements quartz fragments immediately beneath the slag showed extensive pitting that was not apparent in sediments from the background site indicating chemical weathering by the hyperalkaline slag drainage the environmental impacts of slag related mineral precipitation include disruption of natural ground water flow patterns and bed sediment armoring in adjacent surface water systems dissolution of native quartz by the hyperalkaline drainage may cause instability in structures situated over slag fill or in roadways comprised of slag aggregates

palaeoclimate estimates for the middle miocene schrotzburg flora s germany a multi method approach we present a detailed palaeoclimate analysis of the middle miocene uppermost badenian lowermost sarmatian schrotzburg locality in s germany based on the fossil macro and micro flora using four different methods for the estimation of palaeoclimate parameters the coexistence approach ca leaf margin analysis lma the climate leaf analysis multivariate program clamp as well as a recently developed multivariate leaf physiognomic approach based on an european calibration dataset elpa considering results of all methods used the following palaeoclimate estimates seem to be most likely mean annual temperature 15 16 c mat coldest month mean temperature 7 c cmmt warmest month mean temperature between 25 and 26 c and mean annual precipiation 1 300 mm although cmmt values may have been colder as indicated by the disappearance of the crocodile diplocynodon and the temperature thresholds derived from modern alligators for most palaeoclimatic parameters estimates derived by clamp significantly differ from those derived by most other methods with respect to the consistency of the results obtained by ca lma and elpa it is suggested that for the schrotzburg locality clamp is probably less reliable than most other methods a possible explanation may be attributed to the correlation between leaf physiognomy and climate as represented by the clamp calibration data set which is largely based on extant floras from n america and e asia and which may be not suitable for application to the european neogene all physiognomic methods used here were affected by taphonomic biasses especially the number of taxa had a great influence on the reliability of the palaeoclimate estimates both multivariate leaf physiognomic approaches are less influenced by such biasses than the univariate lma in combination with previously published results from the european and asian neogene our data suggest that during the neogene in eurasia clamp may produce temperature estimates which are systematically too cold as compared to other evidence this pattern however has to be further investigated using additional palaeofloras

influence of mg2 on the kinetics of calcite precipitation and calcite crystal morphology abstract the kinetics of calcite growth in the presence of mg2 has been studied by both a ph free drift method and by visual observation our experiments show that the calcite growth rate is reduced by the presence of mg2 the higher the mg ca ratio in the solution the lower the growth rate in a caco3 supersaturated solution the inhibition of calcite growth by the presence of mg2 is caused by mg2 being incorporated into the original calcite seed surfaces and developing new crystal surfaces the mg2 distribution on the calcite surfaces is not uniform as there is likely to be different mg2 densities on the newly developed surfaces than on the original surfaces of the calcite seeds this causes the calcite crystal morphology to change the significance of creating error in using the initial rate data rather than the equilibrium rate data for the prediction of the calcite precipitation kinetics is discussed

the use of a resemblance function in the measurement of climatic parameters from the physiognomy of woody dicotyledons abstract wolfe compiled a data set clamp of the physiognomy of woody dicotyledon leaves with a view to using it to extract climatic information from fossil floras attempts made using these data to identify and describe the relationship between plant physiognomy and climate have all searched for a global relationship applicable throughout data space we investigate the possibility that the relation between climate and physiognomy is so non linear that only local relationships should be sought we use a resemblance function to select sites that are physiognomically similar to each unknown site these similar sites alone yield a climatic estimate for the unknown site data collected from new zealand and australia are then added to wolfe s data set in order to test this new method we show that the use of a resemblance function enables us to produce mean annual temperature estimates for all modern sites that lie within 2 6 c of meteorological data for 90 of the sites this method also allows the objective identification of outliers based on their distance in physiognomic space from their nearest neighbours when a method is used that searches for a global relationship between physiognomy and climate the misfit of estimated mean annual temperature for the combined southern hemisphere and clamp sites is almost twice as great 5 c as that to the clamp sites alone in contrast when the resemblance function is used the rms misfit of estimated mean annual temperature increases by only 0 2 c this result demonstrates the robustness of the new method

deep seismic reflection evidence for continental underthrusting beneath southern tibet the himalaya and adjacent tibetan plateau constituting earth s largest region of elevated topography and anomalously thick crust formed as a consequence of cenozoic collision between india and asia itself considered the archetypal continent continent collision1 3 here we report the first results from an attempt to image the structure of the crust beneath this region using deep seismic reflection profiling our 100 km long profile acquired in the tethyan himalaya shows a mid crustal reflection that prob ably marks the active thrust fault along which the indian plate is underthrusting southern tibet upper crustal reflections with geo metries suggestive of large scale structural imbrication of the upper crust and moho reflections from the base of the double normal thickness crust underlying the region these results lend substantial support to the view that crustal thickening beneath southernmost tibet was accomplished by wholesale underthrusting of indian continental crust beneath the structurally imbricated upper crust comprising the tethyan himalaya

acid neutralization mechanisms and metal release in mine tailings a laboratory column experiment mining and milling of base metal ore deposits can result in the release of metals to the environment when sulfide minerals contained in mine tailings are exposed to oxygen and water they oxidize and dissolve two principal antagonistic geochemical processes affect the migration of dissolved metals in tailings impoundments sulfide oxidation and acid neutralization this study focuses on acid neutralization reactions occurring in the saturated zone of tailings impoundments to simulate conditions prevailing in many tailings impoundments 0 1 mol l sulfuric acid was passed continuously through columns containing fresh unoxidized tailings collected at kidd creek metallurgical site the results of this column experiment represent a detailed temporal observation of ph eh and metal concentrations the results are consistent with previous field observations which suggest that a series of mineral dissolution precipitation reactions control ph and metal mobility typically the series consists of carbonate minerals al and fe iii hydroxides and aluminosilicates in the case of kidd creek tailings the dissolution series consists of ankerite dolomite siderite gibbsite and aluminosilicates in the column experiment three distinct ph plateaus were observed 5 7 4 0 and 1 3 the releases of trace elements such as cd co cr cu li ni pb v and zn were observed to be related to the ph buffering zones high concentrations of zn ni and co were observed at the first ph plateau ph 5 7 whereas cd cr pb as v and al were released as the ph of the pore water decreased to 4 0 or less

cenozoic paleotemperatures and leaf physiognomy a european perspective for 21 european leaf floras with a focus on central europe which span a stratigraphic range from the late eocene to the pliocene paleoclimate estimates have been calculated using five different quantitative techniques a leaf margin analysis lma1 using a regression model based on data from east asia b the multivariate climate leaf analysis multivariate programm clamp technique based on data from east asia and n america c a recently developed multivariate technique based on modern european vegetation elpa d a provisional lma regression model based on the vegetation of several wet localities from n america lma2 and e the coexistence approach ca a technique based on comparisons with the nearest living relatives nlrs of fossil taxa according to our results there seems to be certain discrepancies where the different techniques are compared for paleotemperatures estimates depending mainly on the stratigraphic age of the floras for paleogene floras both multivariate leaf physiognomic techniques are in rather good agreement with ca although both techniques may differ considerably from each other in contrast for the neogene clamp shows a tendency to produce estimates that are considerably colder than ca whereas elpa provides generally warmer estimates and is in better agreement with ca and other independent evidence our results and interpretations add some caveats to temperature reconstructions based on leaf physiognomy especially when applied to european floras from older periods i e paleogene cretaceous possible changes of the relationship between climate and leaf physiognomy over time should be taken into account as a possible source of error whenever such techniques are used there is the possibility that the actual correlation between climate and leaf form may be modified by long time evolutionary responses or floral changes leading to erroneous paleoclimate estimates if a calibration data set is used which is not suited for the region and time interval in question however further research will be needed to test whether such changes in the relationship between climate and leaf physiognomy over time can also be detected on other continents or whether this is a problem restricted to europe

the geochemistry of mine waste pore water affected by the combined disposal of natrojarosite and base metal sulphide tailings at kidd creek timmins ontario since 1985 natrojarosite residue nafe3 so4 2 oh 6 from the zinc refinery at kidd creek near timmins ontario has been disposed of with mine tailings containing up to 25 wt pyrite pore water g

kinetic control of morphology composition and mineralogy of abiotic sedimentary carbonates abstract conventional thinking has long held that the abiotic precipitation of calcium carbonate occurs with a causal relationship between fluid my ca ratios and crystal morphology crystal composition and carbonate mineralogy resulting in the formation of meteoric equant low magnesium calcite and marine acicular high magnesium calcite and aragonite problematically calcites with varying amounts of incorporated magnesium occur either as equant or acicular crystals and aragonite may coexist with calcite in either environment commonly however a systematic relation exists between crystal morphology composition mineralogy and rates of reactant supply to growing crystal surfaces for example equant rather than acicular crystals of calcite form in modern deep and or cold marine meteoric phreatic and deep burial settings where the degree of carbonate saturation and or rates of fluid flow are low in areas of higher saturation and or fluid flow such as in warm shallow marine and meteoric vadose environments acicular calcite may predominate this relation is also seen in systems in which aragonite and calcite form in intimate association aragonite precipitation is favored when rates of reactant supply are high calcite forms when rates are low such relations suggest that crystal morphology composition and mineralogy are controlled by the kinetics of surface nucleation and the amount of reactants principally carbonate ions at growth sites precipitating phases are the ones which can best accommodate such excess reactants ambient mg ca ratios only indirectly control the nature of inorganically precipitated carbonate phases

pb isotope evidence for contaminant metal dispersal in an international river system the lower danube catchment eastern europe abstract lead isotope signatures 207pb 206pb 208pb 206pb 208pb 204pb 206pb 204pb determined by magnetic sector icp ms in river channel sediment metal ores and mine waste have been used as geochemical tracers to quantify the delivery and dispersal of sediment associated metals in the lower danube river catchment due to a diverse geology and range of ore body ages pb isotope signatures in ore bodies within the lower danube river catchment show considerable variation even within individual metallogenic zones it is also possible to discriminate between the pb isotopic signatures in mine waste and river sediment within river systems draining individual ore bodies lead isotopic data along with multi element data were used to establish the provenance of river sediments and quantify sedimentary contributions to mining affected tributaries and to the danube river data indicate that mining affected tributaries in serbia and bulgaria contribute up to 30 of the river channel sediment load of the lower danube river quantifying relative sediment contributions from mining affected tributaries enables spatial patterns in sediment associated metal and as concentrations to be interpreted in terms of key contaminant sources combining geochemical survey data with that regarding the provenance of contaminated sediments can therefore be used to identify foci for remediation and environmental management strategies

geophysical images and a crustal model of intrusive structures beneath the messum ring complex namibia the early cretaceous messum complex in namibia is an excellent example of the type of composite mafic and alkaline igneous ring complexes associated with continental rifts worldwide this study integrates reflection seismic gravity and aeromagnetic data from a profile across messum and reveals a heavily intruded root zone extending vertically to moho depths 40 km the crustal section to either side of the messum complex is characterized by a seismically transparent upper crust to 20 km depth and a laminar reflective lower crust below the crust below the messum complex is seismically transparent at all depths but it shows a combination of high seismic reflection strength and weak coherency relative to the unintruded crust and p velocities about 0 2 0 3 km s higher at all depths the seismic attributes are best explained by a network of mafic intrusions and this is supported by steep sided positive magnetic and gravity anomalies centered on the complex modelling indicates that about 30 gabbroic material in the crustal column can explain the velocity and potential field data an increase in reflective strength below 20 km suggests the degree of intrusion is greater in the lower crust but the difference is not resolved in the velocity or gravity models the new geometric and compositional constraints on the crust below the messum complex contradict the hypothesis that messum was the sole eruptive center for an estimated 8600 km3 of crustally derived rhyodacitic magmas that now form part of the regional parana etendeka volcanic sequences to our knowledge this is the first study to provide a seismic image of the whole crust below a typical igneous ring complex and our conclusion that the cross sectional area of the complex is the same in the lower as in the upper crust could not have been predicted from surface studies the data resolution is insufficient to define intrusion geometry in detail but the cylindrical 3 d shape throughout the crust and the lack of major breaks in the vertical distribution of intrusions indicate depth independent controls on the nature of the intruded zone the suggestion is that the magma transport and emplacement took place in a brittle fashion at all levels of the crust in response to conditions of high fluid magma pressure and a high magma flux

genesis of acid sulfate alteration and au cu ag mineralization at summitville colorado the summitville au cu ag deposit occurs within a porphyritic quartz latite primarily in a zone of vuggy silica alteration characterized by leaching of all major elements except silica and iron vuggy silica is best developed between an elevation of 3 700 and 3 500 m where it occurs in irregular pipes and lenticular pods up to 70 m wide and is enclosed by up to 30 m of intense quartz alunite alteration the vuggy silica zones diminish in size with decreasing elevation and rarely exceed a width of 2 m below an elevation of 3 400 m these deep vuggy silica zones are enclosed by quartz kaolinite alteration with little or no alunite sulfide mineralization occurs primarily within the vuggy silica the sulfide assemblage changes with decreasing elevation from covellite luzonite or native gold to chalcopyrite tennantite sulfides occur lining voids or in microveinlets and are accompanied by minor kaolinitc but not by alunite gold also occurs in a near surface barite goethite jarosite assemblage that crosscuts the vuggy silica consideration of alunite kaolinitc and pyrite stability relations and of aluminum speciation at 250 degrees c indicates that a ph of 2 or below and a log f sub o 2 of 31 or 1 at 250 degrees c were necessary to produce vuggy silica alteration the chalcopyrite tennantite mineralization occurring at depth in the vuggy silica zone is indicative of less oxidizing and less acidic conditions the covellite luzonite or gold assemblage requires conditions intermediate between those necessary for vuggy silica alteration and for deep sulfide mineralization barite gold mineralization is interpreted as a near surface assemblage produced under highly acidic oxidizing conditions these textural and geochemical relationships indicate that sulfide and gold mineralization postdate the formation of vuggy silica alteration in the deposit and are not directly related to the highly acidic solutions necessary for this early acid leaching event the change from extreme acid leaching to copper sulfide and precious metal deposition may represent a transition from a magmatic vapor dominated to a liquid dominated system leading to more reducing and less acidic conditions during sulfide deposition

onset of convective rainfall during gradual late miocene rise of the central andes a decrease in the ratio of 18o to 16o 18o of sedimentary carbonate from the bolivian altiplano has been interpreted to indicate rapid surface uplift of the late miocene andean plateau ap here we report on paleoclimate simulations of andean surface uplift with an atmospheric general circulation model gcm that tracks oxygen isotopes in vapor the gcm predicts changes in atmospheric circulation and rainfall that influence ap isotopic source and amount effects on eastern ap slopes summer convective precipitation increases by up to 6 millimeters per day 500 for plateau elevations that are greater than about 2000 meters high precipitation rates enhance the isotope amount effect leading to a decrease in precipitation 18o at high elevations and an increase in 18o lapse rate our results indicate that late miocene 18o depletion reflects initiation and intensification of convective rainfall

crustal deformation of the lhasa terrane tibet plateau from project indepth deep seismic reflection profiles international deep profiling of tibet and the himalaya indepth deep reflection data in the yangbajain damxung graben of southern tibet yield evidence of magmatism and deformation beneath the southern lhasa terrane and yarlung zangbo suture shallow reflections and low velocity first arrivals indicate a thin quaternary graben fill of generally less than a few hundred meters thickness underlying stratified reflections extending to a maximum of about 11 5 km depth likely originate from deformed paleozoic cenozoic supracrustal strata of the lhasa terrane a prominent undulatory band of reflections within the crystalline basement extends beneath the length of the yangbajain damxung graben depth ranges from 12 km to 18 km this horizon has been interpreted to mark the top of a midcrustal partial melt zone underlying southern tibet the undulatory character of this horizon additionally suggests that it may be tectonically deformed a somewhat deeper subhorizontal wide angle reflection extends southward beneath the outcrop of the yarlung zangbo suture indicating that the suture is cut off or superposed by a younger structure at depth three gently north dipping reflections at 19 km 24 km and 27 km depth beneath the gangdese batholith are suggestive of a midcrustal duplex and may mark the northward downdip extension of the late oligocene early miocene gangdese thrust system a prominent 40 north dipping reflection imaged in the deep crust beneath the gangdese batholith between 40 and 60 km depth might mark the downdip expression of the yarlung zangbo suture or alternatively a younger reverse fault in the lower crust or both viewed in aggregate the reflection data are suggestive of moderate postcollisional shortening of the upper crust of the lhasa terrane accompanied by melting of the middle crust although the data are permissive of wholesale underthrusting or fluid injection of indian continental crust beneath the lhasa terrane they show no direct evidence for this having occurred

a review of the source behaviour and distribution of arsenic in natural waters the range of as concentrations found in natural waters is large ranging from less than 0 5 g l 1 to more than 5000 g l 1 typical concentrations in freshwater are less than 10 g l 1 and frequently less than 1 g l 1 rarely much higher concentrations are found particularly in groundwater in such areas more than 10 of wells may be affected defined as those exceeding 50 g l 1 and in the worst cases this figure may exceed 90 well known high as groundwater areas have been found in argentina chile mexico china and hungary and more recently in west bengal india bangladesh and vietnam the scale of the problem in terms of population exposed to high as concentrations is greatest in the bengal basin with more than 40 million people drinking water containing excessive as these large scale natural as groundwater problem areas tend to be found in two types of environment firstly inland or closed basins in arid or semi arid areas and secondly strongly reducing aquifers often derived from alluvium both environments tend to contain geologically young sediments and to be in flat low lying areas where groundwater flow is sluggish historically these are poorly flushed aquifers and any as released from the sediments following burial has been able to accumulate in the groundwater arsenic rich groundwaters are also found in geothermal areas and on a more localised scale in areas of mining activity and where oxidation of sulphide minerals has occurred the as content of the aquifer materials in major problem aquifers does not appear to be exceptionally high being normally in the range 1 20 mg kg 1 there appear to be two distinct triggers that can lead to the release of as on a large scale the first is the development of high ph 8 5 conditions in semi arid or arid environments usually as a result of the combined effects of mineral weathering and high evaporation rates this ph change leads either to the desorption of adsorbed as especially as v species and a range of other anion forming elements v b f mo se and u from mineral oxides especially fe oxides or it prevents them from being adsorbed the second trigger is the development of strongly reducing conditions at near neutral ph values leading to the desorption of as from mineral oxides and to the reductive dissolution of fe and mn oxides also leading to as release iron ii and as iii are relatively abundant in these groundwaters and so4 concentrations are small typically 1 mg l 1 or less large concentrations of phosphate bicarbonate silicate and possibly organic matter can enhance the desorption of as because of competition for adsorption sites a characteristic feature of high groundwater as areas is the large degree of spatial variability in as concentrations in the groundwaters this means that it may be difficult or impossible to predict reliably the likely concentration of as in a particular well from the results of neighbouring wells and means that there is little alternative but to analyse each well arsenic affected aquifers are restricted to certain environments and appear to be the exception rather than the rule in most aquifers the majority of wells are likely to be unaffected even when for example they contain high concentrations of dissolved fe

characterization of jarosite natrojarosite in two northern scandinavian soils abstract jarosite type minerals mfe 3 so 4 2 oh 6 m k jarosite m na natrojarosite were studied in two sulfic cryaquepts developed in sulfidic sediments deposited in the baltic between 7000 and 4000 bp the jarosites were characterized by x ray diffraction xrd and a selective dissolution technique selective dissolution showed that the k na molar ratio in the jarosites was 0 32 1 27 and the xrd patterns indicated that the jarosite and natrojarosite components formed solid solutions saturated pastes of soil samples were equilibrated for different periods 6 hours to 8 days in order to estimate solubility product constants k so for the jarosite and natrojarosite estimated values of k so for jarosite 10 94 1 10 94 2 corresponded well with literature values for pure or nearly pure synthetic jarosite for natrojarosite only one determination or k so was found in the literature the discrepancy between this value and the k so values obtained in the present study 10 93 1 10 93 9 is about four orders of magnitude which is too large to be explained as an effect of solid solution formation thus we suggest that the literature value is not valid for the pedogenic natrojarosite in these soils i e it is less soluble than the value indicates we hypothesize that natrojarosite forms mainly where the supply of k limits jarosite formation e g under conditions where marine or brackish water has a minor influence the weathering of silicate minerals might be the main source of k and na in such a case by contrast in coastal areas concentrations of k na and so 4 are high and jarosite formation probably is limited by fe oxidation in such environments mainly jarosite is formed owing to its more rapid formation kinetics

the coupled release of ree and pb to the soil labile pool with time by weathering of accessory phases wind river mountains wy abstract rare earth element ree distributions and pb isotope compositions were explored in soils varying in age from ca 0 4 to 300 ka developed on moraines in the wind river mountains wyoming soil extracts 0 6 m hcl were used to examine the soil labile pool while the major element distribution in soil profiles was used to determine the extent of weathering at different soil depths the results show that the chondrite normalized ree patterns of the deepest bulk soil within each profile reflects the composition of the moraine till except for the oldest soil up to ca 12 ka the soil extract fraction is enriched in light ree indicating early release of light ree to the soil labile pool while that of the two oldest soils are relatively enriched in heavy ree in the soil extracts the la sm ratio normalized to the deepest soil la d sm d decreases systematically with soil age similarly the eu anomaly in the deepest soil from each profile eu d eu d decreases slightly with soil age in the three young soils however eu d eu d increases with soil age in the older soils the systematic trends of these two ratios indicate the depletion of light ree in young soils and the enrichment of eu and heavy ree in the older soils based on the pb isotope ratios the relative contribution of pb to the soil labile pool via mineral weathering of u or th rich phases was assessed for the different stages of weathering the whole soil profile 208 pb 204 pb ratio was found to decrease with soil age and with la d sm d whereas it increased with the eu d eu d ratio in each horizon pb isotope ratios 206 pb 204 pb 207 pb 204 pb and 208 pb 204 pb ratio generally decrease with soil age in order to overcome possible effects from parent material heterogeneity the amount of radiogenic pb as compared to the whole soil composition was calculated and this was found to decrease systematically with soil age

rates of weathering and chemical depletion in soils across a chronosequence of lake michigan sand dunes abstract accumulation of soil organic matter and depletion of base cations and trace metals were measured in surface soils i e o horizon and upper 15 cm of mineral soil across a 4150 year soil chronosequence of dune capped beach ridges bordering northern lake michigan within 400 years of beach ridge formation coniferous forest develops soil c and n accumulate to steady state levels of 40 and 1 3 mg ha 1 respectively and the ph of the upper mineral soil decreases from 8 5 to 4 3 as carbonate minerals dissolve after substantial proportions of ca and mg have been removed an incipient spodic horizon can be observed the upper surface of which progressively deepens with increasing soil age analysis of soil strain of the upper mineral soil showed gradual dilation reaching 121 after several centuries of soil development after accounting for soil dilation quantities of ca mg p zn mn fe and v in the upper 15 cm of mineral soil decreased exponentially to low asymptotic levels representing quantities contained in weathering resistant minerals mass balance modeling indicated weathering and elemental losses in the order of decreasing decay constant as ca mg mn zn p v fe al k na ti this sequence is consistent with weathering of carbonates then ferromagnesian minerals then feldspars p levels are tightly coupled with ca losses in soils older than 200 years suggesting that ca rather than fe or al stabilizes p high concentrations of heavy metals in the organic horizon relative to the upper mineral soil indicate atmospheric inputs of industrial pollutants

fault systems of the 1971 san fernando and 1994 northridge earthquakes southern california relocated aftershocks and seismic images from larse ii we have constructed a composite image of the fault systems of the m 6 7 san fernando 1971 and northridge 1994 california earthquakes using industry reflection and oil test well data in the upper few kilometers of the crust relocated aftershocks in the seismogenic crust and larse ii los angeles region seismic experiment phase ii reflection data in the middle and lower crust in this image the san fernando fault system appears to consist of a decollement that extends 50 km northward at a dip of 25 from near the surface at the northridge hills fault in the northern san fernando valley to the san andreas fault in the middle to lower crust it follows a prominent aseismic reflective zone below and northward of the main shock hypocenter interpreted upward splays off this decollement include the mission hills and san gabriel faults and the two main rupture planes of the san fernando earthquake which appear to divide the hanging wall into shingle or wedge like blocks in contrast the fault system for the northridge earthquake appears simple at least east of the larse ii transect consisting of a fault that extends 20 km southward at a dip of 33 from 7 km depth beneath the santa susana mountains where it abuts the interpreted san fernando decollement to 20 km depth beneath the santa monica mountains it follows a weak aseismic reflective zone below and southward of the main shock hypocenter the middle crustal reflective zone along the interpreted san fernando decollement appears similar to a reflective zone imaged beneath the san gabriel mountains along the larse i transect to the east in that it appears to connect major reverse or thrust faults in the los angeles region to the san andreas fault however it differs in having a moderate versus a gentle dip and in containing no mid crustal bright reflections

impact of ancient metal smelting on arsenic pollution in the pecora river valley southern tuscany italy abstract a significant as anomaly has been reported in the literature for stream sediments and unlithified quaternary deposits of the pecora river valley in southern tuscany extending from the colline metallifere pyrite base metals district to the tyrrhenian sea the as anomaly spreads over several square kilometers around a core that exceeds 500 ppm several source contributions from natural to anthropogenic have been invoked to explain the observed as distribution in the pecora valley including the metal working industry which was active in this area particularly in etrusco roman times and in the middle ages in order to evaluate the contribution of ancient mining and metallurgical activities in the pecora valley to elevated as concentrations in the environment a detailed mineralogical and geochemical survey of metallurgical slags and smelted ore minerals was undertaken from six different sites through the pecora valley poggio butelli etrusco roman iron slags sata creek arialla marsiliana forra and cascata sites all medieval base metals slags the as content of etrusco roman slags is relatively low few tens of ppm whereas medieval slags show variable but higher amounts of base metals ag ranging from tens to tens of thousands ppm and as up to 267 ppm with average contents of about 40 ppm arsenic is mostly partitioned in sulfides disseminated through the glassy groundmass rather than in solid solution with the glassy matrix remnants of the ore used for base metal and ag smelting during the middle ages had the highest as contents up to about 1000 ppm the overall as concentration in the slags independent of age and type is generally lower than that found in stream sediments and quaternary alluvial deposit outcrops of the upper pecora valley textural observations indicate that exogenous alteration of slags is minor and mostly confined to superficial exposures of matte droplets or along fractures metal particles embedded within the glassy groundmass even those located a few micrometres from the surface appear to be unaltered it is suggested therefore that as and contaminant metal contributions to the pecora valley by archaeometallurgical slags was minor at least for slags from the last 2500 to 700 a bp similarly based on gross mass balance calculations airborne release of as due to smelting roasting operations in the past cannot account for the observed extent of the as anomaly in stream sediments and quaternary deposits although residues of unsmelted or partially smelted fe cu pb zn charges or fluxes for base metal metallurgy contain much greater amounts of as than smelting slags their relatively low abundance would limit the overall input of as into the pecora river valley on the other hand concurrent research seems to indicate a major geogenic contribution to the as anomaly in the pecora valley

response of meteoric δ18o to surface uplift implications for cenozoic andean plateau growth abstract the timing and magnitude of surface uplift provide important constraints on geodynamic models of orogen formation oxygen isotope 18 o and mass 47 isotopolog 47 compositions from terrestrial carbonate sediments have been used with modern isotope and temperature lapse rates to infer past surface elevations of the andes however these paleoaltimetry interpretations are contentious because variations in the oxygen isotope composition in meteoric water 18 o p are caused by changes in elevation orographic and regional climate here we use a limited domain isotope tracking general circulation model to simulate changes in 18 o p and isotopic lapse rates in response to andean surface uplift and to re evaluate 18 o and 47 changes in late miocene carbonates previously associated with rapid andean growth results indicate that andean surface uplift leads to changes in low level atmospheric circulation and an increase in precipitation along the eastern andean flank which influences isotopic source and amount effects simulated changes in andean 18 o p are not systematic with an increase in surface elevation but are instead a function of orographic thresholds that abruptly change regional climate a 18 o p decrease of 5 over the central andes and an increase in isotopic lapse rates up to 0 8 km 1 coincide with andean surface uplift from 75 to 100 of modern elevation these changes in the isotopic signature could account for the entire 3 4 18 o depletion in late miocene carbonate nodules and suggest an andean paleoelevation of 3000 m 75 of modern elevations before 10 ma

early diagenesis atherton formation quaternary a guide for understanding early cement distribution and grain modifications in nonmarine deposits abstract the atherton formation represents an extensive sheet of outwash and related materials of quaternary age these sand q77f8r15 and gravel sediments are locally lithified and present an excellent opportunity for evaluating the effects of early diagenesis on a terrigenous deposit the principal cement present is calcium carbonate 98 occurring as euhedral to anhedral grain contact pore lining and porefilling varieties limonite and gypsum are present as rare cements cement distribution was controlled at various levels by 1 stratification character 2 grain size and sorting 3 framework grain composition and 4 proximity to near surface processes initial cement development and subsequent early growth were primarily parallel to laminae within beds this precipitation site preference is related to initially higher relative permeabilities estimated at 2 to 2 5 x parallel versus normal to stratification when associated with trough cross strata cements preferentially are located in the lower portion of troughs or directly below trough set boun aries there is a slight preference for early formed cements to be present along the axis instead of the flanks of a trough about 50 of pebble gravel and sandy pebble gravel units contain locally cemented zones while 17 of finer grain size strata are locally lithified over 95 of locally cemented units are within 7 m of the present ground surface suggestive of a causal relation to near surface perhaps soil related processes the sources for the various constituents composing cements are related to the dissolution of previously cemented layers and framework components such as carbonate rock fragments calcareous pelitic rock fragments and iron bearing silicate grains the examination of oversized voids elongate pores and intraparticle porosity suggests that at least locally multiple episodes of cementation followed by dissolution have taken place reactions between carbonate cement and limestone rock fragments have destroyed a high percentage of detrital carbonate grain boundaries such reactions combined with early dissolution can result in an information loss in excess of 50 of the limestone rock fragment component in a sandstone a combination of organic acids and co2 mixed with meteori waters is likely responsible for the dissolution and transportation of cement constituents

mineralogy and environmental geochemistry of historical iron slag hopewell furnace national historic site pennsylvania usa the hopewell furnace national historic site in southeastern pennsylvania which features an fe smelter that was operational in the 18th and 19th centuries is dominated by three slag piles pile 1 slag from the hopewell furnace and pile 2 slag likely from the nearby cornwall furnace were both produced in cold blast charcoal fired smelters in contrast pile 3 slag was produced in an anthracite furnace ore samples from the nearby jones and hopewell mines that fed the smelter are mainly magnetite rich with some sulfides pyrite chalcopyrite sphalerite and accessory silicates quartz garnet feldspar and clay minerals slag piles 1 and 2 are similar mineralogically containing predominantly skeletal and dendritic aluminian diopside and augite skeletal forsteritic olivine glass rounded blebs of metallic fe and exotic quartz olivine is a major phase in all samples from pile 2 whereas it occurs in only a few samples from pile 1 samples of the 2 mm size fraction of surface composite slag material or crushed slag from at depth in piles 1 and 2 are mineralogically similar to the large surface slag fragments from those piles with the addition of phases such as feldspars fe oxides and clay minerals that are either secondary weathering products or entrained from the underlying bedrock pile 3 slag contains mostly skeletal forsteritic olivine and ti bearing aluminian diopside dendritic or fine grained subhedral melilite glass euhedral spinel metallic fe alabandite oldhamite solid solution as well as a sparse ti carbonitride phase the bulk chemistry of the slag is dominated by al2o3 8 5 16 2 wt cao 8 2 26 2 wt mgo 4 2 24 7 wt and sio2 36 4 59 8 wt constituting between 81 and 97 of the mass of the samples piles 1 and 2 are chemically similar pile 1 slag overall contains the highest fe2o3 k2o and mno and the lowest mgo concentrations pile 3 slag is high in al2o3 cao and s and low in fe2o3 k2o and sio2 compared to the other piles in general piles 1 and 2 are chemically similar to each other whereas pile 3 is distinct a conclusion that reflects their mineralogy the similarities and differences among piles in terms of mineralogy and major element chemistry result from the different smelting conditions under which the slag formed and include the fuel source the composition of the ore and flux the type of blast cold versus hot which affects the furnace temperature and other beneficiation methods the three distinct slag piles at hopewell are enriched in numerous trace elements such as as up to 12 mg kg cd up to 0 4 mg kg co up to 31 8 mg kg cu up to 647 mg kg mn up to 0 69 wt pb up to 172 mg kg and zn up to 393 mg kg together with fe 13 9 wt when compared to the average for the continental crust with the 2 mm size fraction commonly containing the highest concentrations enrichments in various elements e g cd co cu pb zn were also found in the ore samples despite these enrichments comparison of bulk chemistry trace element concentrations to the environmental guidelines suggests most elements are likely not problematic with the exception of as co fe and mn leachate tests that simulate weathering indicate fe up to 973 g l and mn up to 133 g l are readily released in potentially harmful concentrations compared to secondary drinking water and some aquatic ecosystem toxicity criteria aluminum and cu although not high in the solid compared to environmental guidelines also exceed relevant criteria in leachate extracts with maximum concentrations of 2700 g l and 17 7 g l respectively in contrast as and co which are significant in the solids are not leached in concentrations that exceed guidelines i e 3 g l or less for both elements the weathering rates of the fe metal and fe oxides which host cu and some fe are likely higher than the silicate glass which hosts the majority of al mn and some fe and the crystalline silicates and spinels affecting which elements and how much are released into the environment and surrounding aquatic ecosystem the mineral assemblages and their chemical composition the bulk sample chemistry and leachability of trace elements are all important components in understanding the potential environmental impacts of the slag piles

direction and timing of uplift propagation in the peruvian andes deduced from molecular phylogenetics of highland biotaxa abstract physical paleoaltimetric methods are increasingly used to estimate the amount and timing of surface uplift in orogens because the rise of mountains creates new ecosystems and triggers evolutionary changes biological data may also be used to assess the development and timing of regional surface uplift here we apply this idea to the peruvian andes through a molecular phylogeographic and phylochronologic analysis of globodera pallida a potato parasite nematode that requires cool temperatures and thus thrives above 2 0 2 5 km in these tropical highlands the peruvian populations of this species exhibit a clear evolutionary pattern with deeper more ancient lineages occurring in andean southern peru and shallower younger lineages occurring progressively northwards genetically diverging g pallida populations thus progressively colonized highland areas as these were expanding northwards demonstrating that altitude in the peruvian andes was acquired longitudinally from south to north i e in the direction of decreasing orogenic volume this phylogeographic structure is recognized in other independent highland biotaxa and point to the central andean orocline cao as the region where high altitudes first emerged moreover molecular clocks relative to andean taxa including the potato tomato group consistently estimate that altitudes high enough to induce biotic radiation were first acquired in the early miocene after calibration by geological and biological tie points and intervals the phylogeny of g pallida is used as a molecular clock which estimates that the 2 0 2 5 km threshold elevation range was reached in the early miocene in southernmost peru in the middle and late miocene in the abancay segment nw southern peru and from the latest miocene in central and northern peru although uncertainties attached to phylochronologic ages are significantly larger than those derived from geochronological methods these results are fairly consistent with coeval geological phenomena along the peruvian andes they strongly suggest that orogenic volume initially developed in the cao during most of the miocene until a breakthrough in the latest miocene allowed the northward propagation of crustal thickening into central and northern peru possibly by ductile crustal flow from the cao such a combined phylogeographic and phylochronologic approach to regional uplift opens perspectives to estimate the direction s and timing of acquisition of altitude over other cenozoic orogens

large scale dataset from china gives new insights into leaf margin temperature relationships leaf margin analysis lma is an important method of estimating paleotemperatures from fossil leaf floras or modern floras although some calibration has been carried out based upon large scale studies of modern forests most of this research has been in north america and europe with relatively little calibration work in east asia in the present study we used species range maps of 3116 native dicot trees of china to derive synthetic local floras for each county from the chinese humid region and compared the percentage of untoothed leaf margined species with several temperature and precipitation related parameters the results confirm the generally strong relationship between the proportion of species with untoothed leaf margins and climatic parameters within china leaf habit deciduous vs evergreen does not strongly affect this relationship the transfer function obtained from china while not identical is similar to those obtained from other regions and is affected by regional restrictions such as complex topography and relic taxa as such it clarifies the potential range of error inherent in the lma method as applied to paleodimate reconstruction it is possible however that with the close similarity of the modern chinese tree floras to neogene floras in the northern hemisphere the present estimate offers a better transfer function for reconstructing the neogene paleoclimate in various regions without extremely cold conditions across the northern hemisphere c 2014 published by elsevier b v

migration why doesn t it work for deep continental data summary conventional migration of deep seismic reflection data often produces disappointingly poor results even when the original unmigrated data are of high quality and are relatively noise free surprisingly deep data often subjectively appear to be best migrated at velocities which are up to 50 less than appropriate interval velocities derived from crustal refraction experiments or directly from stacking velocities the explanation for this behaviour is that near surface features distort and attenuate the seismic wave field and produce apparent discontinuities in deep reflections since these discontinuities are spurious they are not associated with the appropriate large diffractions which real discontinuities at depth would produce during the process of migration reflections are invented in order to cancel out the missing diffractions thereby producing a smiley section which appears overmigrated since the lateral extent of individual smiles increases with increasing migration velocity increasing two way time and increasing seismic wavelength the effect is almost unnoticeable on conventional shallow seismic data but is overwhelming for deep crustal data

inorganic calcite morphology roles of fluid chemistry and fluid flow abstract evaluation of calcite crystal habits and fabric and their relation to precipitating fluids in spelean environments indicates that habit variations are controlled primarily by degree of supersaturation at less than 6 times supersaturation crystal habits are limited to those with shallow to steep rhombohedral forms i e 1011 4041 with increasing supersaturation scalenohedrons extremely steep rhombohedrons pinacoids and hexagonal prisms are developed slight elongation due to differences in crystal dimensions of these forms may arise i e scalenohedrons versus shallow rhombohedrons at extreme supersaturation 12 times curvature of crystal faces or curved surfaces appear the development of fibrous versus equant fabrics is the result of changes or modification of reactant supply rates and the number of crystallites nuclei present under rapid flow conditions growth rates are accelerated and greater numbers of nuclei are present thus compromise boundaries parallel to c axis and perpendicular to flow and substrate are rapidly attained in the absence of flow fewer crystallites are present and larger well developed crystals or branching forms dictated by saturation conditions arise in the absence of flow at low supersaturation elongate composite crystals and hence fibrous fabrics may result from migration of the fluid crystal interface as a result of changing or oscillating water levels a flow control mechanism can be applied to numerous geological conditions in which transitions from fibrous to equant crystal morphologies are observed

mineralogical and geochemical controls on the release of trace elements from slag produced by base and precious metal smelting at abandoned mine sites slag collected from smelter sites associated with historic base metal mines contains elevated concentrations of trace elements such as cu zn and pb weathering of slag piles many of which were deposited along stream banks potentially may release these trace elements into the environment slags were sampled from the ely and elizabeth mines in the vermont copper belt from the copper basin mining district at ducktown tennessee and from the clayton silver mine in the bayhorse mining district idaho in the usa primary phases in the slags include olivine group minerals glass spinels sulfide minerals and native metals for vermont samples glass sulfide minerals and native metals for the ducktown sample and olivine group minerals clinopyroxenes spinels sulfide minerals native metals and other unidentified metallic compounds for clayton slag olivine group minerals and pyroxenes are dominantly fayalitic and hedenbergitic in composition respectively and contain up to 1 25 wt zno spinel minerals range between magnetite and hercynite in composition and contain zn up to 2 07 wt zno ti up to 4 25 wt tio2 and cr up to 1 39 wt cr2o3 cobalt ni cu as ag sb and pb occur in the glass phase sulfides metallic phases and unidentified metallic compounds bulk slag trace element chemistry shows that the metals of the vermont and tennessee slags are dominated by cu 1900 13 500 mg kg and zn 2310 10 200 mg kg whereas the clayton slag is dominated by pb 63 000 mg kg zn 19 700 mg kg cu 7550 mg kg as 555 mg kg sn 363 mg kg and ag 200 mg kg laboratory based leach tests indicate metals can be released under simulated natural conditions leachates from most slags were found to contain elevated concentrations of cu and zn up to 1800 and 470 g l respectively well in excess of the acute toxicity guidelines for aquatic life for the idaho slag the concentration of pb in the leachate 11 000 g l is also in excess of the acute toxicity guideline geochemical modeling of the leachate chemistry suggests that leachates from the vermont tennessee and clayton slags are saturated with amorphous silica and al hydroxide therefore the dissolution of silicate and oxide phases the oxidation of sulfide phases as well as the precipitation of secondary phases may control the composition of leachate from slags the presence of secondary minerals on slag deposits in the field is evidence that these materials are reactive the petrographic data and results of leaching tests from this study indicate slag may be a source of potentially toxic metals at abandoned mine sites

oxygen isotope and paleobotanical estimates of temperature and δ18o latitude gradients over north america during the early eocene empirical estimates of climate parameters such as mean annual temperature mat are essential to describe both ancient climate and to ground truth climate model simulations of past climates in terrestrial settings no single proxy record is able to provide detailed temporal yet geographically widespread information and it thus becomes essential that paleoclimatic information obtained from different proxies be comparable as an example of how to compare estimates and to illustrate what can be learned by doing so we measured oxygen isotope ratios of phosphate in the tooth enamel of fossil mammals and the body scales of freshwater fish in order to estimate the mean annual temperature mat in which they lived the samples were collected from paleogene rocks of the bighorn green river and powder river basins of wyoming earliest eocene samples provide mat estimates that are similar to mat estimates for the same times and areas obtained from leaf margin analysis furthermore isotopic data from the paleocene eocene thermal maximum petm which has not yet yielded fossil floras indicate a significantly higher mat of 26 c we also used temperature estimates obtained by both methods to investigate paleoelevation and to reconstruct geographic patterns of mat over north america for the early eocene larger laramide basins have higher temperatures and lower inferred elevations compared to associated volcanic highlands where cooler temperatures are consistent with substantial elevations in turn latitudinal gradients in temperature indicate that warming centered on polar regions played an important role during the eocene hothouse lastly we show that the reconstructed eocene relation between oxygen isotope ratios of precipitation and mat is significantly different from the modern relation between these two variables because the relation has changed over time the modern correlation should not be used to estimate paleo mat from measurements of oxygen isotope ratios in fossil material

continuous estimation of 3 d reflector orientations along 2 d deep seismic reflection profiles abstract interpretation of 2 d deep seismic reflection data can be limited by the recording of out of plane reflections that cannot be readily distinguished from those originating beneath a seismic line here i present a method analogous to semblance velocity analysis that utilizes varying source receiver azimuths to derive continuous estimates of 3 d reflector orientations along onshore 2 d reflection profiles for each zero offset time within a common depth point supergather the semblance is calculated along 3 d travel time curves and the dip and strike of the most coherent reflection is determined relative errors in these angles are derived from the range of travel time curves that have semblance values greater than a specified fraction for example 90 of the maximum the method is illustrated using a section from line 10ga yu1 from the youanmi terrane of the yilgarn craton in australia in which the original field data have been replaced with synthetic in line and cross line reflections reflector orientations are generally well recovered where the range of available source receiver azimuths is greater than 20o but the method fails at lower ranges where the seismic line is almost linear and this behavior is also observed in analysis of the field data nevertheless when using a realistic 1 d velocity function the orientation of upper crustal shear zones can be readily determined and on unmigrated sections subhorizontal sills can be distinguished on the basis of their geometry from the mid crustal reflectivity in future surveys reflector orientations can be determined along the near linear sections of a seismic profile by deploying additional receivers perhaps as cross line recording spreads to supplement the limited range of azimuths available from the in line acquisition the method can in principle be extended to marine reflection surveys and more complex sub surface velocity models

crustal structure of the eastern dabie shan interpreted from deep reflection and shallow tomographic data abstract a 20 km long seismic line characterises the crustal reflection pattern of the easternmost dabie shan the archetypal ultrahigh pressure uhp orogen of eastern china the weak to non reflective upper crust 5 s two way travel time twt 15 km depth is interpreted to comprise uhp rocks thrust over lithologically similar but non uhp crust the tectonic contact although not imaged as a distinct reflector is probably outlined by the rather abrupt change to diffuse but strong reflectivity within the mid to lower crust thus the seismic pattern of the upper crust implies that mafic oceanic crust does not constitute a significant proportion the middle to lower crust 5 10 s twt 15 33 km depth probably represents cratonal yangtze basement unaffected by the uhp metamorphism the prominent lowermost reflectors 10 12 s twt 33 40 km depth are interpreted to trace the moho excluding the presence of a crustal root inherited from the uhp orogeny a tomographic p wave velocity model for the uppermost crust

mean annual temperature estimation based on leaf morphology a test from tropical south america abstract are models that predict mean annual temperature mat from leaf morphology applicable globally fifteen models that predict mat from leaf morphology were tested on thirty floral samples from tropical south america to determine the degree to which models based on published data that are primarily from other regions are applicable to floras from tropical south america the models included are based on regional data from north america south america and asia of the fifteen models tested five are simple linear regressions six are multiple linear regressions two are canonical correspondence analyses and two are correspondence analyses followed by nearest neighbor analyses for the seven modern floras with mat 21 c every model overestimates mat for the 23 modern floras with mat 21 c all models produce variable results without a systematic error the range of average model errors is 2 7 7 3 c while the absolute extremes of error are 0 and 15 1 c average 95 predictive confidence intervals range from 1 6 to 6 9 c predicted mat falls within the published standard error of the model for 0 67 of the south american test floras evaluating the seven sites with mat 21 c separately from the 23 sites with mat 21 c shows that no equation accurately estimates mat of the majority of low temperature sites but that four equations accurately estimate 50 of high temperature sites the results suggest that at least for sites of unknown or high elevation mean annual temperature of fossil floras from tropical south america may be better predicted from models based on the leaf morphology of tropical south american floras

modelling of modern mercury vapor transport in an ancient hydrothermal system environmental and geochemical implications mercury has been used in some mineralizing hydrothermal systems as a significant pathfinder of au and other elements in addition its geochemical behaviour reflects some characteristics related to the transport mechanism of metal bearing fluids in this work the authors analyse the geochemical aspects and the environmental impact of hg mobilization from the old mining area of valle del azogue va from smelting slags mining waste and the partially exploited mineralization that remains a few metres underground the main pathway of hg is the transport of vapor from different foci therefore a mathematical simulation of the process of hg vapor transport was carried out in the valle del azogue va mineral deposit this is one of the two sites in spain the other being the famous district of almaden where hg vapor emissions have been cited the results obtained by means of mathematical simulation were compared with both the real hg concentration values detected in the field upper part of the mining area and with the geochemical distribution patterns of au and other elements related to the mineralization a close relationship between the simulated hg vapor distribution and soil gas concentrations was identified it is proposed that the transport of hg emissions from this old mining area could be the cause of present contamination of marine sediments in the area

quantitative reconstruction of the late miocene monsoon climates of southwest china a case study of the lincang flora from yunnan province the miocene lincang leaf assemblage is used in this paper as proxy data to reconstruct the palaeoclimate of southwestern yunnan sw china and the evolution of monsoon intensity three quantitative methods were chosen for this reconstruction i e leaf margin analysis lma climate leaf analysis multivariate program clamp and the coexistence approach ca these methods however yield inconsistent results particularly for the precipitation as also shown in european and other east asian cenozoic floras the wide range of the reconstructed climatic parameters includes the mean annual temperature mat of 18 5 24 7 degrees c and the mean annual precipitation map of 1213 3711 mm compared with the modem lincang climate mat 17 3 degrees c map 1178 7 mm the miocene climate is slightly warmer wetter and has a higher temperature seasonality a detailed comparison on the palaeoclimatic variables with the coeval late miocene xiaolongtan flora from the eastern part of yunnan allows us to investigate the development and interactions of both south asian and east asian monsoons during the late miocene in southwest china now under strong influence of these monsoon systems our results suggest that the monsoon climate has already been established in southwest yunnan during the late miocene furthermore our results support that both southeast asian and east asian monsoons co occurred in yunnan during the late miocene c 2010 elsevier b v all rights reserved

iron and aluminum hydroxysulfates from acid sulfate waters acid sulfate waters are produced mostly by the oxidation of common sulfide minerals such as pyrite chalcopyrite pyrrhotite and marcasite in rocks soils sediments and industrial wastes this spontaneous process of mineral weathering plays a fundamental role in the supergene alteration of ore deposits the formation of acid sulfate soils and the mobilization and release of acidity and metals to surface and ground waters the purely natural process of acid rock drainage is often intensified by human activities related to mining mineral processing construction soil drainage and dredging geochemical reaction rates are accelerated because physical disturbance gives greater exposure of mineral surfaces to air and water and to microbes that catalyze the reaction process large quantities of reactive sulfides are also concentrated and exposed to air as a result of mining and mineral processing acid sulfate waters produce a number of fairly insoluble hydroxysulfate and oxyhydroxide minerals that precipitate during oxidation hydrolysis and neutralization the objective of this chapter is to describe the formation properties fate and environmental implications of the nano to microphase hydroxy sulfates of fe and al that are precipitated from acid sulfate waters these minerals are commonly of poor crystallinity and difficult to characterize much remains to be learned about their occurrence formation and properties mine drainage the best known examples of acid sulfate waters are those released from mines where coal and metallic sulfide ores have been exploited ash et al 1951 barton 1978 nordstrom 1982a rose and cravotta 1998 nordstrom and alpers 1999 there may be as many as 500 000 inactive or abandoned mine sites in the united states alone lyon et al 1993 although most of these pose no immediate water quality problem kleinmann 1989 estimated that about 19 300 km of streams and more than 72 000 ha of lakes and reservoirs have been

the relationship between leaf physiognomy and climate based on a large modern dataset implications for palaeoclimate reconstructions in china abstract in this paper correlation between modern leaf physiognomy and climate in china are examined to optimize the use of leaf characters as a palaeoclimate proxy a large dataset was compiled recording the distribution of leaf physiognomic characters among 3166 native dicot trees species across 732 calibration grids on a county level grids span a range of ecological environments tropical rainforests to alpine shrubs across humid areas thirteen climatic parameters were included for each grid and 22 leaf physiognomic characters were scored for each tree species the correlation between leaf physiognomic characters and climatic parameters were calculated based on single linear regressions slr and multiple linear regressions mlr results indicate clear spatial distribution patterns linked to latitude exist for all leaf characters with temperature coldest month mean temperature cmmt and precipitation growing season precipitation gsp being the main climate controls moreover because leaf characters are more closely correlated with precipitation during the three wettest consecutive months p3wet rather than with precipitation during the three driest consecutive months p3dry seasonal variations in rainfall associated with the asian monsoon might especially influence leaf physiognomic characters closer correlations between leaf physiognomy and climate are seen using mlr compared with slr therefore mean annual temperature mat and mean annual precipitation map based on mlr equations provide the most promising basis for palaeoclimate reconstructions in china

refining clamp investigations towards improving the climate leaf analysis multivariate program clamp climate leaf analysis multivariate program has been used for the past 17 years to estimate palaeoclimatic conditions the reliability and applicability of this method based on leaf physiognomic characters of fossil woody dicots has been widely discussed over the same period the present study focuses on some technical aspects of clamp mainly on its robustness in the context of the theoretical unimodal requirements of canonical correspondence analysis and introduces correction coefficients for these aspects of the statistical approach as a new way of interpreting and improving on clamp estimates this tool was tested on datasets derived from 17 european fossil floras ranging in age from the late oligocene to the pliocene additionally an objective statistical method for the selection of the best suited modern vegetation dataset from 144 site physg3br or 173 physg3ar extant biotopes is proposed

contribution of saharan dust to mediterranean soils assessed by sequential extraction and pb and sr isotopes abstract measurements of the concentrations and isotopic composition of pb and sr in al silicates and fe oxides of two soil profiles developed in the guadalquivir river basin andalusia southwestern spain are used in order to estimate the significance of local versus foreign sources lead concentrations are 10 6 mg kg in deep more than 100 cm soil samples and reach 30 60 mg kg near the surface 206 pb 207 pb values range from 1 200 to 1 206 in deep samples and from 1 186 to 1 191 in the upper most samples sr concentrations range from 30 to 69 mg kg showing no systematic trend with depth 87 sr 86 sr ratios range from 0 71753 to 0 72526 also with no systematic changes with depth in the fe oxide fraction but with a systematic increase in values with depth in the al silicate fraction of one of the soil profiles in all the samples the isotopic composition of pb in the al si fraction is slightly more radiogenic than its value in the fe oxide fraction the isotopic composition of sr exhibits the opposite behavior and 87 sr 86 sr values in the fe oxide fraction are always higher than in the al silicate fraction based on our data we calculate that al silicates in the fine soil fraction less than 5 m in both sites contain 33 86 of saharan dust and that the fe oxides contain less saharan dust and more material released by the weathering of basement granitoid type rocks in the case of pb a third source is present in the upper part of the soil i e anthropogenic pb probably added to the soil over millennia the results of the present study suggest that saharan dust makes up a significant fraction in al silicates and fe oxides of mediterranean soils but that local sources both natural rock derived and anthropogenic are not trivial

slags from ruda śląska poland as a large scale laboratory for the crystallization of rare natural rocks melilitolites and paralavas abstract zinc and lead smelting slags from ruda l ska are unique in their chemistry and phase composition which resemble rare natural rocks such as paralavas and melilitolites moreover considering its size we can treat a pyrometallurgical slag dump as a geological body in slags from ruda l ska the assemblage melilite pseudowollastonite wollastonite plagioclase was discovered in glassy slag high temperature experiments were performed to determine the temperature conditions and to reconstruct the crystallization of such an assemblage two slag samples were subjected to complete melting and crystallization with controlled thermal gradients of 53 25 c h 15 20 c h and 7 60 c h the results showed that crystal nucleation started at temperatures of 1250 1300 c depending on the fluctuations of chemical composition in both samples the thermal gradient only partly influenced the phase differentiation being rather responsible for the disappearance of the primary glass moreover even slight differences in chemical composition resulted in changes in phase assemblages under the same temperature conditions mll gls vs pwol pl mll gls it was proven that it is due to the combination of undercooling conditions and solidus dependences in the akermanite gehlenite solid solution the occurrence of such phenomena should be considered in natural rocks with similar composition in the case of the ruda l ska slags it explains the dominance of glassy slag in that location the experiments gave us an opportunity to observe and precisely analyze crystallization in real time providing new insights into the creation of slags and their natural analogues however the study has also shown that possible variations of the original crystallization should always be assessed

quantification of large uncertainties in fossil leaf paleoaltimetry 1 estimates of paleoelevation potentially constrain geodynamic models of continental deformation and inform interpretations of landscape and climate evolution one widely used paleobotanical approach reconstructs paleoelevation from the difference in estimated atmospheric enthalpy between a known sea level and a targeted coeval elevated fossil floral site enthalpy is estimated using climate leaf analysis multivariate program clamp on 31 leaf size and shape variables that have been calibrated in living forests errors related to clamp are significantly greater than often reported and there are many sources of large potential error related to this method that are either difficult to quantify or unquantifiable and are thus not documented here we quantify one significant bias toward underestimation of leaf area in the clamp data set 50 that affects all clamp climate estimates including enthalpy crucially errors in paleoelevation when the leaf size bias is included are in the range of 2 km or more at least 2 times the previous estimates and exceeding the plausible paleoelevations of many fossil sites previously published paleoelevations derived from this technique are unlikely to be accurate either in magnitude or in estimated error

lead isotopic systematics of major river sediments a new estimate of the pb isotopic composition of the upper continental crust abstract the lead isotopic composition of river sediments is reported in the present work for the earth s major river basins from old cratonic to young orogenic areas and from subarctic to tropical climates sediment samples from these large river basins provide a useful tool to calculate the average upper crustal composition because they are large scale integrated samples of the weathering products of the present day upper continental crust ucc two different and complementary calculations were done to estimate the average lead isotopic composition of the ucc the first based on the flux weighted average of particulate lead delivered by the rivers gave values of 19 07 15 74 and 39 35 for 206 pb 204 pb 207 pb 204 pb and 208 pb 204 pb ratios respectively to avoid over estimating the contribution of orogenic areas which produces a bias because the flux of particulate lead depends strongly on the physical erosion rate a second calculation was done by averaging with drainage areas of each river basin this gave values of 18 93 15 71 and 39 03 for 206 pb 204 pb 207 pb 204 pb and 208 pb 204 pb ratios respectively these direct calculations of the lead isotopic composition of the ucc are similar and are in agreement with previous estimates made using an indirect approach

tectonic events reflected by palaeocurrents zircon geochronology and palaeobotany in the sierra baguales of chilean patagonia abstract the sierra baguales situated north of the torres del paine national park in the magallanes region of southern chile shows a well exposed stratigraphic sequence ranging from the late cretaceous to late pliocene which presents a unique opportunity to study the evolution of sedimentological styles and trends palaeoclimate changes and tectonic events during this period the depositional environment changed from a continental slope and shelf during the cenomanian campanian tres pasos formation to deltaic between the campanian maastrichtian dorotea formation and estuarine in the lutetian bartonian man aike formation during the rupelian a continental environment with meandering rivers and overbank marshes was established rio leona formation this area was flooded in the early burdigalian estancia 25 de mayo formation during the patagonian transgression but emerged again during the late burdigalian santa cruz formation measured palaeocurrent directions in this mesozoic cenozoic succession indicate source areas situated between the northeast and east southeast during the late cretaceous east southeast during the middle eocene and southwest during the early oligocene to early miocene this is confirmed by detrital zircon age populations in the different units which can be linked to probable sources of similar ages in these areas the east southeastern provenance is here identified as the antarctic peninsula or its northeastern extension which is postulated to have been attached to fuegian patagonia during the eocene the southwestern and western sources were exhumed during gradual uplift of the southern patagonian andes coinciding with a change from marine to continental conditions in the magallanes austral basin as well as a decrease in mean annual temperature and precipitation indicated by fossil leaves in the rio leona formation the rain shadow to the east of the andes thus started to develop here during the late eocene early oligocene 34 ma long before the quechua phase of andean tectonics 19 18 ma that is generally invoked for its evolution at lower latitudes

pb concentrations and pb isotope ratios in soils collected along an east west transect across the united states abstract analytical results for pb concentrations and isotopic ratios from ca 150 samples of soil a horizon and ca 145 samples of soil c horizon collected along a 4000 km east west transect across the usa are presented lead concentrations along the transect show 1 generally higher values in the soil a horizon than the c horizon median 21 vs 16 5 mg kg 2 an increase in the median value of the soil a horizon for central to eastern usa missouri to maryland when compared to the western usa california to kansas median 26 vs 20 mg kg and 3 a higher a c ratio for the central to eastern usa 1 35 vs 1 14 lead isotopes show a distinct trend across the usa with the highest 206 pb 207 pb ratios occurring in the centre missouri median a horizon 1 245 c horizon 1 251 and the lowest at both coasts e g california median a horizon 1 195 c horizon 1 216 the soil c horizon samples show generally higher 206 pb 207 pb ratios than the a horizon median c horizon 1 224 a horizon 1 219 the 206 pb 207 pb isotope ratios in the soil a horizon show a correlation with the total feldspar content for the same 2500 km portion of the transect from east central colorado to the atlantic coast that shows steadily increasing precipitation no such correlation exists in the soil c horizon the data demonstrate the importance of climate and weathering on both pb concentration and 206 pb 207 pb isotope ratios in soil samples and natural shifts thereof in the soil profile during soil forming processes

paleoclimatic estimates from tertiary leaf assemblages a primary obstacle to evaluating numerical modeling of tertiary nonmarine climates has been the significance and reliability of proxy data sloan barron 1990 lacking direct measurements of paleoclimatic parameters inferred paleoclimatic values are based on substitute proxy sources such as fossils or isotopes are proxy data significant that is have they been calibrated in modern environments and to what level is the calibration this is the problem of accuracy validity in the statistical sense second are the proxy data reliable can two workers or even the same worker consistently arrive at the same estimates using the same data set this is the problem of precision repeatability can these two problems be resolved quaternary palynologists have used the concept of transfer functions a methodology originally developed for foraminifera imbrie kipp 1971 applied in palynology a response surface for each palynomorph taxon is constructed for the environmental variables under consideration these transformations can then be subjected to a number of different kinds of multivariate analyses including ordination methodologies bartlein et al 1986 webb bryson 1972 these transfer functions can work for quaternary and especially the lateand post glacial of the last 20 to 30 thousand years pollen assemblages because in most regions where the methodology has been applied the flora is of known diversity and the equivalency of a given palynomorph species to one or a few extant species can be reasonably assumed even in the late neogene 1 5 to 10 million years ago however this assumption can no longer be made we know that the palynomorph assemblages contain exotic genera mccartan et al 1990 and the presence of exotic and or extinct species

an oligocene microthermal forest dominated by nothofagus in sierra baguales chilean patagonia response to global cooling and tectonic events abstract a large fossil leaf assemblage 3700 specimens is reported from the oligocene rio leona formation in the sierra baguales of chilean patagonia the association comprises 29 species but is dominated by nothofagus genera which constitutes 65 of specimens the collection can be classified as a mixed palaeoflora of the austral antarctic association stratigraphic analysis of the assemblage indicates a decrease in species diversity and richness over time which was accompanied by species turnover quantitative studies of foliar morphology clamp leaf margin analysis indicates cool to cold and dry climatic conditions with a mean annual temperature of 9 2 c a relatively high seasonality in temperature and precipitation and a mean annual precipitation of 931 mm nothofagus only became dominant in southeastern patagonia during the rupelian coinciding with a marked global cooling period linked to the initiation of glaciation in antarctica about 34 ma the decrease in precipitation following this event is attributed to the development of a rain shadow to the east of the rising southern patagonian andes which must have been of the order of 1000 m or more for topographic climate forcing to take effect this contrasts with the rain shadow development east of the andes at lower latitudes which was mainly manifested after the middle miocene

comment on rapid uplift of the altiplano revealed through 13c 18o bonds in paleosol carbonates based on stable isotope measurements ghosh et al reports 27 january 2006 p 511 concluded that the bolivian altiplano uplifted 3 to 4 kilometers between 10 3 and 6 7 million years ago as a result of gravitational loss of dense lithosphere this result stands at odds with current geological knowledge of the central andes and we propose a test for the reliability of the paleoaltimetry method

reply to comment on rapid late miocene rise of the bolivian altiplano evidence for removal of mantle lithosphere by garzione et al 2006 earth planet sci lett 241 2006 543 556

indepth international deep profiling of tibet and the himalaya multichannel seismic reflection data description and availability project indepth international deep profiling of tibet and the himalaya has collected over 300 km of multichannel deep seismic reflection data using explosive sources as part of a multidisciplinary effort to image the structure of the crust and uppermost mantle of the tibetan plateau the reflection profiles lie within the yadong gulu rift and were acquired in the summers of 1992 and 1994 data processing utilized typical industry tools and a new method was used to migrate the data both unmigrated and migrated sections are presented here in large format to facilitate further interpretations

multiple archaean to early palaeozoic events of the northern gondwana margin witnessed by detrital zircons from the radzimowice slates kaczawa complex central european variscides sims dating of detrital zircons from the stratigraphically enigmatic radzimowice slates of the kaczawa mountains sudetes sw poland near the eastern termination of the european variscides has yielded age populations of 1 493 512 ma corresponding to late cambrian to early ordovician magmatism and constraining a maximum depositional age 2 between 550 and 650 ma reflecting input from diverse cadomian sources and 3 older inherited components ranging to c 3 3 ga with age spectra similar to those from gondwanan north africa the new data show that the radzimowice slates cannot form a proterozoic base to the kaczawa mountains succession as suggested by earlier models but was deposited at the earliest as an extensional basin fill during a relatively late stage of the break up of this part of northern gondwana

estimation of rainfall variables from leaf characters in tropical africa abstract regression models are defined for leaf physiognomic and climate variables from 30 modern equatorial african plant communities herbarium specimens provide physiognomic data for published species lists for the 30 sites climate data are from a variety of published sources by limiting the sampled region to equatorial africa where annual amount and seasonality of rainfall are critical determinants of vegetation leaf physiognomy is found to be related linearly to moisture variables principal components analysis demonstrates that the pattern of variation among leaf variables is primarily a function of mean annual and wet months total of all months with 50 mm rainfall multiple regression models are derived for mean annual rainfall wet months rainfall and the number of dry months accuracy of each model is tested by comparing the adjusted predicted values the value for a case when it is not included in calculation of the regression line to the actual climate values at the 30 sites leaf size is the strongest correlate of moisture the mesophyll size class has the most significant positive relationship with annual and wet months rainfall entire margined species increase with wet months rainfall and temperature acuminate tip and length width ratio are also positively related to mean annual and wet months rainfall rounded base emarginate tip and acute tip are inversely related to rainfall variables regression models derived from modern plants and climate can be used to reconstruct seasonal and annual rainfall from cenozoic african leaf fossils

the biosphere a homogeniser of pb isotope signals abstract rock soil and plant terrestrial moss european mountain ash leaves mountain birch leaves bark and wood and spruce needles and wood samples collected at 3 km intervals along a 120 km long transect 40 sites cutting the city of oslo norway were analysed for their pb concentration and pb isotope ratios a general decrease in 206 pb 207 pb 208 pb 207 pb and 206 pb 208 pb ratios with a characteristic low variability in all plant materials and the plant derived o horizon of soil profiles compared to rocks and mineral soils is observed along the transect it is demonstrated that minerogenic and biogenic sample materials belong to two different spheres the lithosphere and biosphere and that geochemical processes determining their chemical and isotopic compositions differ widely background variation for both sample materials needs to be established and documented at the continental and global scale before the anthropogenic influence on the geochemistry of the earth s surface can be reliably estimated

jarosites and their application in hydrometallurgy the alunite supergroup consists of more than 40 minerals with the general formula dg 3 t o4 2 oh h2o 6 wherein d represents cations with a coordination number greater or equal to 9 and g and t represent sites with octahedral and tetrahedral coordination respectively smith et al 1998 the supergroup is commonly subdivided into various groups but the simplest primary subdivision is on the basis of the g cations for all of the minerals in the supergroup the dominant g cation is trivalent most of the minerals have g represented by fe3 or al3 but exceptions are the rare minerals gallobeudantite in which g is ga3 and springcreekite in which g is v3 table 1 thus the primary grouping adopted here is on whether formula fe3 exceeds or is subordinate to al3 the hierarchical sequence in mineralogy seems to be variable but here the decreasing sequence is given as supergroup family group and subgroup minerals with fe3 al3 are referred to as belonging to the jarosite family and those with a13 fe3 are allocated to the alunite family view this table table 1 minerals of the alunite supergroup subdivision of the alunite and jarosite families has also been variable scott 1987 for example used seven groups novak et al 1994 used six gaines et al 1997 used four and mandarino 1999 used three the arbitrary decision here is to use three groups which differ from those of mandarino 1999 but which in general indicate whether sulfate phosphate or arsenate predominates in the t o4 tetrahedra the three groups are the alunite group in which t o4 is dominated by so4 the crandallite group in which po4 is

a comment on rapid late miocene rise of the bolivian altiplano evidence for removal of mantle lithosphere by c n garzione et al earth planet sci lett 241 2006 543 556

anthropogenic and lithogenic sources of lead in lower silesia southwest poland an isotope study of soils basement rocks and anthropogenic materials to discriminate possible anthropogenic and lithogenic sources of pb in lower silesia sw poland the pb isotope composition was investigated in a spectrum of rocks and anthropogenic materials as well as within 10 soil profiles silicate rocks in lower silesia have 206 pb 207 pb ratios that vary from 1 17 for serpentinites to 1 38 for gneisses and this variability is reflected in the isotope composition of the mineral soil horizons the pb isotope composition of coals ores and anthropogenic materials slags and fly ashes is rather uniform with 206 pb 207 pb ratios ranging from 1 17 to 1 18 similar ratios were observed in ore and coal samples from upper silesia the o soil horizons also have uniform 206 pb 207 pb ratios of 1 17 1 18 and the heterogeneity of the 206 pb 207 pb ratios increases with depth in the soil profiles five soils with varying pb concentrations analysed far from contamination centres show consistent approximately 2 fold enrichment in pb concentration from the c to a horizons which is consistent with natural re distribution of pb within the profiles the increase in the pb concentration is accompanied by a decrease in 206 pb 207

lead and strontium isotopes as monitors of experimental granitoid mineral dissolution abstract flow through dissolution experiments were carried out on crushed granitoid rock the elat granite and three mineral separates plagioclase perthite and biotite chlorite from this rock at ph 1 and 25 c major element concentrations were combined with pb and sr isotopic analyses of starting materials and output solutions and together enabled us to elucidate several important mechanisms related to granitoid rock weathering we observed an initial stage of rock dissolution

end member models for andean plateau uplift abstract diverse techniques have been applied over the past decade to quantify the uplift history of the central andean plateau ap in this study opposing models for surface uplift are evaluated including a rapid rise of 2 5 km 10 6 ma and a slow and steady rise since 40 ma these end member models are evaluated by synthesizing observations of the ap lithosphere and the history of deformation sedimentation exhumation magmatism uplift and fluvial incision structural and geophysical studies estimate variable shortening magnitudes 530 150 km involving cover to basement rocks an isostatically compensated thick crust 80 65 km high heat flow and zones of variable velocity and attenuation in the crust and mantle these observations have invoked interpretations such as a hot weak lithosphere partial melt crustal flow and perhaps current localized delamination but do not provide strong support for massive delamination required by the rapid uplift model deformation and associated exhumation began 60 40 ma and generally migrated eastward with consistent long term average shortening rates 12 8 mm yr in bolivia favoring the slow uplift model volcanic and helium isotope evidence show an ap wide zone of shallow mantle melting and thin lithosphere that has existed since 25 ma which is inconsistent with the rapid rise model that suggests lithospheric thinning occurred 10 6 ma paleoaltimetry data suggest a rapid 2 5 km elevation gain 10 to 6 ma but are equally consistent within error with a linear rise since 25 ma widespread fluvial incision 2 5 1 km occurred along the western flank since 11 8 ma and may be associated with surface uplift as proposed by the rapid rise model however the paleoaltimetry and incision data can also be explained by regional climate change associated with plateau uplift implications of these results for reconstructions of ap evolution are that 1 substantial deformation of a weak lithosphere is essential 2 ap growth has taken significantly longer 40 myr and was more uniform along strike 1500 km than previously appreciated and 3 the slow and steady uplift model is most consistent with available constraints we conclude that the rapid uplift model may be an overestimate and that a more protracted cenozoic uplift history is tenable

isotopic composition of lead in moss and soil of the european arctic moss o and c horizons of podzols mainly forming complementary sample triplets as well as filter residues of molten snow from northern norway northern finland and nw russia have been analyzed by tims for their pb isotopic composition in order to study the impacts of local geogenic anthropogenic sources and long range atmospheric transport on the pb balance in the european arctic samples were taken along two n s transects covering an area of 188 000 km2 including both pristine environments in the w and certain regions towards the e severely contaminated by heavy metal emissions originating from large nickel smelters and processing plants in nw russia the lead in moss and o horizon samples clearly reflects atmospheric deposition as it displays overall uniform isotope ratios and is decoupled from the geogenic background i e the underlying mineral soils in the c horizon moss and o horizon samples from the eastern n s transect are isotopically indistinguishable from those taken along the western transect but their pb concentrations tend to be 2 times higher this points to considerable contamination originating from the nearby russian industrial and urban centers however isotopic signals of emissions from individual industrial point sources cannot be unambiguously identified because they lack characteristic isotope signatures pb derived from gasoline additives is swamped by pb from other sources and can also be excluded as a major contributor to the environmental pb in the european arctic overall the pb isotopic signatures of moss and o horizon overlap values recorded in atmospheric lead all over central and southern europe more than 2000 km south of the study area this may be taken as indicating continent wide mixing of pb derived from similar sources in the atmosphere or as reflecting economic globalization or both o horizon samples which accumulate lead over 20 30 yr conform to a distinct pb isotope reference line in 207pb 206pb vs 208pb 206pb space european standard pollution esp defined by atmospheric pb considered to be representative for the technical civilization in europe conversely the arctic moss samples with a lifetime of 3 yr display a deviating linear trend reflecting a recent change of atmospheric input towards significantly more radiogenic pb derived from mississippi valley type ores in the u s fully compatible with signatures found in epiphytic lichens from canada but also in pb from urban waste incinerators in central europe considering the elevated pb concentrations in moss collected along the eastern n s transect this congruence indicates that the pb in moss of the european arctic most probably originates from the nearby russian centers of urbanization and not from transatlantic transport we therefore suspect imported industrial goods and their subsequent attrition to be a more plausible explanation for the appearance of mvt lead in europe

a simple method for migrating narrow aperture noisy seismic reflection data and application to project indepth international deep profiling of tibet and the himalaya deep seismic profiles migration of deep seismic data is often hindered by a narrow recording aperture line length by record length and a low signal to noise ratio the severity of typical migration artifacts e g lateral smearing of discontinuous reflections into synforms smiles increases with travel time such that interpreters of deep seismic data have often substituted migrated line drawings for the actual sections as part of project indepth international deep profiling of tibet and the himalaya a new migration method was developed to address both the noise and migration issues the method works in the time space domain and uses the simple constant velocity straight ray path to perform the migration first only amplitudes within a given range are retained for migration thus avoiding high amplitude noise bursts and low amplitude background noise then the local dip of a reflection is found by automatically fitting a straight line to the highest amplitudes within a small window several time samples by several traces and calculating the dip of the line using a constant velocity finally using this dip the method migrates a selected amplitude value the dips lateral positions and depths of the migrated events compare very well with output from more conventional algorithms e g fk stolt finite difference etc the advantages of the new method include fewer artifacts fast computer run times low memory use and the ability to migrate long profiles and travel times e g 50 s the output of the method is a grid of migrated amplitudes not wavelets or dip values which is particularly effective for making small figures such as those needed for publication the principal disadvantage is the use of a constant migration velocity