experimental study of boron geochemistry implications for fluid processes in subduction zones a comprehensive experimental study utilizing an autoclave hydrothermal apparatus with a 10b isotopic tracer has been conducted to monitor the geochemical behavior of sediment b during early subduction zone processes the partition coefficient of exchangeable b kd was determined over a temperature range of 25 350 c at 800 bars and a water rock ratio of 3 1 5 w w these kd are shown to be a complex function of temperature ph and possibly mineralogy at low temperatures kd is significantly high at 4 in contrast to the value of essentially zero at temperatures higher than 100 c a kd of zero represents no b adsorption implying efficient mobilization of exchangeable b at shallow depths during sediment subduction our experimental results demonstrate high mobilization of bulk b in sediments both exchangeable and lattice bound at elevated temperatures 200 350 c in good agreement with previous observations of b in metasediments indicating progressive depletion during metamorphism in addition this study emphasizes the importance of a possible water rock ratio dependence of b mobilization in other words the degree of sedimentary b mobilization in subduction zones strongly depends on the local thermal structure and porosity distribution in low geothermal gradient areas large amounts of porewater are expelled before significant b mobilization has occurred so that some sedimentary b will survive and get into the deeper parts of the subduction zone our results imply that efficient mobilization of b from the subducted slab must occur and that arc magmatism recycles most of the remaining subducted b back to surface reservoirs a reconsideration of the b budget in subduction zones provides critical information with respect to b sources and sinks in the ocean

petrogenesis of tourmaline rocks associated with fe carbonate graphite metapelite metabasite and strata bound polymetallic sulphide mineralisation peloritani mountains sicily southern italy abstract tourmalinite and tourmaline rich rocks associated with fe carbonate graphite phyllite strata bound polymetallic sulphide deposits metabasite and marble were studied for information on the mechanism of tourmaline formation in the pre hercynian low grade metamorphic sequence of the mandanici unit in the peloritani mountains of sicily southern italy the major and trace element compositions of the tourmaline rocks suggest the existence of a sedimentary protolith with pre metamorphic black shale and bedded chert boron was interpreted to be accumulated in a restricted sedimentary basin between platform carbonate formations with abundant organic matter and fe al ti rich laterite bauxite soil derived clastic supply under a continental volcano tectonic extensional regime accompanied by a local convective hydrothermal system along faults petrographic crystal chemical and 11 b isotopic data are compatible with a model of marine sediment dewatering at temperatures below 200 c which caused the removal of boron from clay metamorphism led to the development of tourmaline in an al ti rich environment in equilibrium with other minerals such as ilmenite albite and muscovite the upper temperature of metamorphism almost 375 c estimated on the basis of 11 b fits geothermometric results from 13 c carbonate graphite on associated rocks the estimated value of 11 b in the tourmalinite protolith 7 5 is also compatible with continental derived al rich sediments

a centennial scale record of vegetation and climate variability from 312 to 240 ka marine isotope stages 9c a 8 and 7e from tenaghi philippon ne greece abstract based on a new centennial scale resolution pollen record from the terrestrial site of tenaghi philippon ne greece we report a series of high amplitude millennial scale forest expansion events during the interval from 312 to 240 ka equivalent to isotopic substages c a of marine isotope stage mis 9 mis 8 and the onset of mis 7e pollen based indices support the climatic interpretation of the forest expansion events as indicators of abrupt increases in temperature and moisture availability in the mediterranean region long term changes in vegetation cover and composition during the studied interval permit the definition of glacial substages early middle and late analogous to the glacial substages of the last climatic cycle within this framework forest expansion events occurred during the early glacial equivalent to mis 9c a and the later part of the middle glacial mid to late mis 8 but are absent from the early part of the middle glacial early mis 8 forest expansion events are also detected during the lateglacial and onset of mis 7 associated with a millennial scale climate oscillation across the glacial interglacial transition i e termination iii t iii a peak for peak match between forest expansion events and antarctic temperature maxima suggests interhemispheric coupling of millennial scale climate variability via global oceanic circulation change and synergistic variability in atmospheric circulation consistent with the bipolar see saw the resolution of our record mean 290 yr also permits the characterisation of climate evolution over the course of interstadial episodes following forest expansion events and highlights differences in the characteristics of early and middle glacial interstadials saw tooth vs plateau profile these differences point to an influence of long term boundary conditions especially global ice volume on the characteristics of millennial scale events

boron isotope variations in nature a synthesis the large relative mass difference between the two stable isotopes of boron 10b and 11b and the high geochemical reactivity of boron lead to significant isotope fractionation by natural processes published 11b values relative to the nbs srm 951 standard span a wide range of 90 the lowest 11b values around 30 are reported for non marine evaporite minerals and certain tourmalines the most 11b enriched reservoir known to date are brines from australian salt lakes and the dead sea of israel with 11b values up to 59 dissolved boron in present day seawater has a constant world wide 11b value of 39 5 in this paper available 11b data of a variety of natural fluid and solid samples from different geological environments are compiled and some of the most relevant aspects including possible tracer applications of boron isotope geochemistry are summarized

middle pleistocene variations in palaeoclimate palaeoenvironment and vegetation of the las tablas de daimiel national park spain the middle pleistocene palaeoclimate and palaeoenvironment evolution of the las tablas de daimiel wetlands is described using a combination of sedimentology pollen and d 13 c and d 18 o isotopic records of unit b of core lt 199906 this unit mostly contains fluvial and palustrine sediments u th and amino acid racemization aar dating and a comparison of the d 18 o curve of unit b with oceanic records suggests that unit b spans the period from the end of marine isotope stage mis 10 340 ka to the first stages of mis 7 ca 210 ka mis 9 was characterised by a regional vegetation dominated by cupressaceae with pinus as a tree element the water level was high and temperatures were very probably higher than during the holocene mis 8 and the first substages of mis 7 7e 7d and 7c were dominated by xerophilous steppe vegetation in lowlands elevations around 610 m above sea level near to the wetland at higher altitudes far away from the wetland there were fewer pinus than in mis 9 and a greater presence of warm temperate and cool climate tree elements the aquatic system in mis 9 became shallower with eutrophication and the accumulation of organic matter occurring temperatures were similar to or lower than those of the holocene copyright 2011 john wiley sons ltd

tourmalines from appalachian caledonian massive sulfide deposits textural chemical and isotopic relationships tourmaline is a common gangue mineral in several strata bound massive sulfide deposits of the appalachian caledonian orogen most of the tourmaline rich deposits occur in dominantly metasedimentary terranes such as bleikvassli norway black hawk maine ore knob north carolina and elizabeth vermont minor amounts of tourmaline are also known in association with volcanic hosted deposits in the appalachians and in the trondheim district of norway the tourmaline forms isolated euhedral crystals or crystal aggregates in massive sulfide and adjacent wall rocks in a few areas it is found in conformable tourmaline rich layers tourmalinites associated minerals may include quartz plagioclase phlogopite and dolomite with pyrrhotite chalcopyrite galena and sphalerite many of the tourmaline crystals are optically zoned in which brown zones concentrically alternate with pale yellow or green zones a few specimens of tourmaline intergrown with massive sulfide e g ore knob display fine delicate growth lamellae similar to those commonly observed in hydrothermal vein sphalerites skarn garnets and sphalerites from the massive sulfide deposits of the kuroko district japan detailed geochemical studies indicate that the tourmalines have characteristic major and trace element compositions electron microprobe analyses show that with rare exception the tourmalines are mg rich dravites avg feo feo mgo 0 21 abrupt transitions between color zones within some tourmaline are accompanied by relative variations in feo feo mgo of as much as 30 percent yellow brown zones are more mg rich than blue or green zones in contrast the fine growth lamellae are not characterized by such variations in chemistry spectrographic analyses of pure mineral separates indicate that the tourmalines also contain high average contents of cr 78 ppm cu 77 ppm pb 114 ppm sr 98 ppm and v 195 ppm while uniformly low in li 7 ppm and mn 382 ppm in all analyzed samples fluorine is much more abundant than chlorine the average f cl ratio is 33 tourmalines from tourmalinites and massive sulfide deposits are typically characterized by heavier delta 18 o values 9 5 15 5ppm and less variable heavier delta d values generally 45 to 60ppm than tourmalines from unmetamorphosed igneous pegmatites the latter typically have delta 18 o 9 5 per mil and delta d or 60 per mil oxygen isotope fractionations between quartz and tourmaline delta 1 27 4 01 do not correlate directly with inferred grade of subsequent metamorphism although in areas of high metamorphic grade the delta values approach those of igneous quartz tourmaline pairs the delta 18 o values of quartz and tourmaline are believed to reflect variation in the oxygen isotope compositions of the host lithologies the similar narrow range in hydrogen isotope composition for tourmaline in all studied deposits is compatible with a modified seawater origin for the tourmaline and sulfide forming fluids the distinctive textural and chemical characteristics of the tourmalines reported here have both exploration and genetic significance though it may have undergone recrystallization and some accompanying chemical and isotopic exchange during regional metamorphism tourmaline in the massive sulfide deposits is an early formed perhaps diagenetic mineral in which fine lameliar zoning may be a preserved premetamorphic feature in any case the tourmalines from the massive sulfide deposits are mg rich dravites with trace element and stable isotope compositions substantially different from those of the fe rich schorls typical of most granitic rocks these geochemical and isotopic signatures are attributed to the original environment of formation of the associated sulfide deposits and suggest that mg rich tourmaline may be a valuable prospecting guide in the search for massive sulfide deposits

the middle paleolithic site of cuesta de la bajada teruel spain a perspective on the acheulean and middle paleolithic technocomplexes in europe here we present a pluridisciplinary study of cuesta de la bajada site teruel spain our findings show that the site contains an early middle paleolithic assemblage similar to other european early middle paleolithic industries allowing us to evaluate the coexistence of this industrial tradition with the acheulean technocomplex in southwest europe the process of lithic production at cuesta de la bajada represents a technology focused on debitage the application of technical concepts such as ramified production sequences and the recycling of flakes via the resharpening of tools and exhausted cores this site was formed around a pond not far from a river and contains remains of large macrofauna other than equids and cervids taphonomic analysis highlights the abundance of cut marks on bones and supports the hypothesis of selective hunting by hominids the numerical ages derived from the combination of esr osl and aar dating methods indicate that the archaeological site was very likely formed around the mis 8 mis 9 the appearance of middle paleolithic industries in europe could represents the autochthonous development of a technocomplex distinctly different from the acheulean characterised by chaines operatoires of debitage and a progressive increase of levallois technology and retouched tools these results suggest that there is a clear coexistence of assemblages with acheulean and middle paleolithic industries during the last third of the middle pleistocene at least in the iberian peninsula

climate and vegetation changes 180 000 to 345 000 years ago recorded in a deep sea core off portugal a new high resolution combined marine proxy pollen sequence from the portuguese margin md01 2443 enables direct comparison of ocean and ice volume changes with vegetation development in south west iberia during marine isotope stages mis 7 8 and 9 changes in sea surface conditions on both orbital and millennial time scales are closely mirrored by forest extent indicating a coherence of climate variability between the north atlantic and south west iberia deglacial warming at the start of mis 7 and 9 was interrupted by incursions of subpolar water masses at the site accompanied by reversals in tree population expansion during mis 7e and 9e the close relationship in timing and amplitude between vegetation and offshore conditions broke down early forest collapse points to pronounced cooling and aridification on land which although not accompanied by a change in water masses at the portuguese margin appears to have coincided with abrupt decreases in atmospheric methane concentration recorded in antarctic ice cores the most extreme glacial conditions of mis 8 occurred during the early part followed by an interval of warmer conditions and tree population expansion similar to 263 ka this has sometimes been considered as indicating an early deglaciation but the data presented here show that it was distinct from termination iii which occurred later in line with milankovitch forcing a sub orbital oscillation in both isotopic and pollen records is observed at the end of mis 7 ca 184 ka which appears to be coeval with a recently identified sea level high stand c 2006 elsevier b v all rights reserved

a least squares approach to mass transport calculations using the isocon method a statistically rigorous approach based on the isocon method grant 1986 to evaluate mass transport is presented chemical analyses of multiple samples of unaltered parent and altered rock are used to calculate the average oxide or element concentration and its standard deviation for each rock population in a typical application the uncertainties in element concentration associated with the lack of homogeneity in each population outweigh the analytical uncertainty an efficient algorithm is presented to select the immobile elements by identifying the maximum number of elements that are within their uncertainties compatible with the same isocon the actual isocon is constructed by forcing a line through the origin and optimizing its slope using a weighted least squares procedure for the selected immobile elements thus individual uncertainties for each immobile element are taken into account as an illustration the procedure is applied to a published set of data on potassic and sericitic alterations of quartz monzonite of the bingham porphyry copper system the surprising result indicates that the apparent increase of potassic alteration phases is a consequence of acid leaching of calcium and sodium no mass transport of potassium is indicated silica water and sulfur were added during alteration the best fit isocon requires a small mass increase during each alteration process which however is within the uncertainty obtained for the slope of the isocon a software package is available from the authors in the form of a fortran 77 source code

comparison of changes in vegetation in northeast greece with records of climate variability on orbital and suborbital frequencies over the last 450 000 years abstract a new direct pollen orbital tuning procedure based on a correspondence between changes in certain vegetation elements and march and june perihelion configurations is applied to the tenaghi philippon record northeast greece the development of a refined chronological scheme allows comparisons to be made with records of climate variability from the north atlantic as well as of global sea level ice volume and atmospheric co2 content on orbital frequencies the comparison reveals a close correspondence between relative ice volume extent and tree population size during glacial intervals during interglacial and interstadial periods the degree of forest development is more closely associated with high latitude insolation and related climate regimes rather than extent of residual ice volume on suborbital frequencies the greek record shows similar repeat times in peaks of steppe vegetation with north atlantic ice rafting events but the amplitude of this variability in the two records is not always proportional overall what emerges is that the major shifts in the relative abundance of forest v open vegetation communities at tenaghi philippon on orbital and suborbital frequencies over the last 450 000 years are coherent with high latitude changes affecting atmospheric and oceanic circulation glacial decreases in atmospheric co2 content contributed to the elimination of tree populations by exacerbating water stress conditions during arid intervals but do not appear to be the primary driver of the observed vegetation changes at this latitude variations in co2 levels in the order of 40 ppmv between different interglacial interstadials periods with adequate moisture availability appear to have had a limited effect on the nature and size of tree populations

structural trends and palaeogeography of the central and western sicily belt new insights the geology of the sicilian mainland is summarized by n s geological sections a continuous late cenozoic orogenic belt through central and western sicily resulted from a complex deformative history recorded by several tectonic events the deformation mainly involved the sedimentary cover of the old african continental margin formed in a large basinal area bordered at its southern margin by a shallow water carbonate environment attached to gondwana the orogenic belt involves a complex architecture of thrust systems of different size geometry and palaeogeographical origin deformation which mainly developed in the earlier stages of thrusting in the basinal rock assemblages mainly gave rise to a stack of three different duplex structures respectively composed of palaeozoic mesozoic palaeogene and neogene strata large scale clockwise rotation of the thrusts predated transpressional movements in the hinterland during the latest miocene to pliocene high angle reverse faults with lateral components modified earlier tectonic contacts within the allochthons contemporaneous southwards directed imbrications affected the external southern areas progressively incorporating foreland and piggyback basirts the stratigraphic relationships of basin fills to the tectonic structures reveals that reactivation processes have been active during the last plio pleistocene

chemical and boron isotope composition of tourmaline from the kiaka orogenic gold deposit burkina faso west african craton as a proxy for ore forming processes the kiaka orogenic gold deposit burkina faso located in the paleoproterozoic domain of the west african craton is characterized by a two stage gold mineralization hosted in volcano sedimentary metamorphic rocks that was formed during the eoeburnean 2 20 2 13 ga and eburnean 2 13 2 05 ga orogenic cycles these two stages include an early disseminated low grade gold mineralization and a late vein hosted high grade gold mineralization paragenetic studies indicate that the first gold stage was coeval with the deposition of hydrothermal tourmaline the aim of this paper is twofold i to determine the processes responsible for deposition of the economic disseminated gold mineralization and ii to identify the source of the mineralizing fluids for this purpose we performed an in situ study on tourmaline by combining electron probe microanalysis and secondary ion mass spectrometry measurements of boron isotopes hydrothermal tourmaline hosted in metamafic volcanic rocks and metagreywackes has a dravite composition but shows different 11b values falling within the two intervals of 25 1 to 22 0 and 19 6 to 15 1 respectively our results suggest that tourmaline formed from a distal high temperature ca 400 c reduced and low salinity hydrothermal fluid that interacted with the local host rocks based on the modeling of tourmaline fluid boron isotope fractionation we propose a metamorphic fluid origin derived from devolatilization of deeply buried muscovite schists during the regional prograde to peak metamorphism prior ca 2 13 ga this metamorphic fluid rock interaction model may possibly extend to other orogenic gold deposits in the west african craton

geological relationships and u pb zircon and 40 ar 39ar tourmaline geochronology of gneisses and tourmalinites from the nevado filabride complex western sierra nevada spain tectonic implications abstract the nevado filabride complex the lowest complex in the betic hinterland forms a stack of alpine nappes the tectonic units consist of metasedimentary sequences whose ages are not well constrained gneiss bodies included in the sequences have been one of the few sources of geochronological data in this metamorphic complex new radiometric data from u pb zircon dating on gneisses from the western sierra nevada confirm the presence of late carboniferous intrusive rocks in the betic hinterland these results combined with available data from the literature and a detailed structural analysis suggest that the gneisses represent a single late variscan magmatic event evidence for a close genetic relation between gneisses and tourmalinites is provided by field and petrographic observations in conjunction with geochemical data u pb zircon 314 7 304 23 ma and 40 ar 39 ar tourmaline 319 85 5 81 317 85 3 67 ma geochronology a pre late carboniferous age for the basal formation of the nevado filabride sequence can be inferred the gneiss protolith and the graphite schist are considered to be the boron source and the precursor of the tourmalinites respectively superposed tectonic units rather than a continuous palaeozoic sequence is supported by the occurrence of palaeozoic rocks at the top of the nevado filabride complex the nappe tectonics as evidenced from the contractional character of the unit boundaries and the superposition of higher grade on lower grade metamorphic rocks is additionally supported by the superposition of older on younger rocks as revealed from radiometric data

exploration of driving mechanisms of equilibrium boron isotope fractionation in tourmaline group minerals and fluid a density functional theory study abstract the equilibrium boron isotope fractionations 3 4 11b tur fluid between tourmaline mineral groups and fluids at 0 5 gpa 600 1000 k are investigated using density functional theory calculations the first solvent shell controls boron isotope fractionation in solution where the values of both h3bo3 and b oh 4 decrease with increasing numbers of hydrogen bonds in supercritical fluids the weakening of hydrogen bonds and the diversity in configurations of hydrated boron species both contribute to variations in the vibrational frequencies the 1000ln tur fluid value increases with increasing mg fe mg ratios in the dravite schorl solid solution series this effect together with the crystallization sequence predicted from the gibbs free energies of tourmaline formation accounts well for the association of boron isotope and chemical zonation observed in zoned tourmaline grains the dependence of boron isotope fractionation on the b o bond length in tourmaline group minerals reflects the changes in relevant molar volumes caused by differences in the mass and charge of the atoms occupying the x y and z sites of tourmalines this study suggests that the chemical composition of the tourmaline plays an important role in controlling the boron isotope composition in tourmalines crystallized from hydrothermal systems

four climate cycles of recurring deep and surface water destabilizations on the iberian margin centennial climate variability over the last ice age exhibits clear bipolar behavior high resolution analyses of marine sediment cores from the iberian margin trace a number of associated changes simultaneously proxies of sea surface temperature and water mass distribution as well as relative biomarker content demonstrate that this typical north south coupling was pervasive for the cold phases of climate during the past 420 000 years cold episodes after relatively warm and largely ice free periods occurred when the predominance of deep water formation changed from northern to southern sources these results reinforce the connection between rapid climate changes at mediterranean latitudes and century to millennial variability in northern and southern polar regions

differential mobility of elements in burial diagenesis of siliciclastic rocks abstract mass balance calculations involving smectite rich siliciclastic mudstones sampled from boreholes show that significant k2o addition and cao loss correlate strongly with the progress of illitization of smectite and with the dissolution of calcite the calculations are based on the immobility of al2o3 and require a chemically homogeneous sediment at deposition such that the shallower samples represent protolith compositions of deeper samples constancy of ratios of tio2 al2o3 are used to 1 establish that both tio2 and al2o3 have similarly low differential mobilities and 2 identify stratigraphic sections available in the literature that are sufficiently homogeneous to allow the calcu ations our calculations show that most major oxide components are immobile at the 5 limit of resolution of the calculations exceptions are k2o which is almost universally added to mudstones and cao which is commonly removed from mudstones during diagenesis the addition of up to 50 k2o correlates with percent illite in mixed layer illite smectite indicating that illitization of smectite involves fixation of k2o from diagenetic fluids removal of 40 cao from some sections correlates with decreasing calcite mode and is attributed to dissolution of calcite together these reactions lead to a 10 15 loss of mineral volume a volume loss that must be added to porosity loss when modeling compaction illitization and carbonate dissolution may be linked because k fixation during illitization decreases the ph of the local fluid a reverse weathering reaction which enhances carbonate dissolution addition of up to 20 na2o in some rocks may be caused by albitization of plagioclase but na2o addition is not pervasive the apparent lack of mass transfer associated with dissolution of kaolinite and feldspars or precipitation of chlorite implies that these reactions are balanced by other reactions such that their oxide components in mudstones are conserved limited data from sandstone mudstone pairs are consistent with transfer of k2o from sandstones to mudstone via rising diagenetic fluids except for cao and the alkalis diagenesis of siliciclastic mudstones appears isochemical 5 relative for most major oxide components the much larger changes recorded in some reservoir sandstones are clearly exceptions and may not reflect changes occurring at the scale of kilometers

chemical and boron isotope compositions of tourmaline in the hadamiao porphyry gold deposit inner mongolia china abstract the hadamiao porphyry gold deposit in inner mongolia china is located in the northern margin of the north china craton ncc tourmaline is a common mineral in hydrothermal veins and granitic rocks contemporaneous with the mineralized granite porphyry in this deposit the tourmaline can be divided into six types including magmatic tourmaline tur m1 in granite porphyry dikes magmatic hydrothermal transitional tourmaline tur m2 in nodular granitic rocks and hydrothermal tourmalines in early tourmaline veins tur v1 gold bearing quartz tourmaline chalcopyrite veins tur v2 breccia cements tur v3 and late carbonate quartz veins tur v4 the gold mineralization is closely related to the occurrence of tur v2 almost all the tourmalines from the hadamiao deposit belong to the alkali group and show a schorlitic dravitic composition except for some tur m1 belonging to uvite the concentrations of most elements in different tourmaline types overlap tur m1 has higher ca w th u pb mn and zr contents than other types and the hydrothermal tourmalines v1 v4 show slightly higher ba cu and y contents than tur m1 and tur m2 the concentration of au in tur m1 and tur m2 can reach up to 80 ppb and is higher than that in tur v1 the au content in tur v2 is an order of magnitude higher than that in other stages of tourmaline systematic contrasts in major and trace element compositions between magmatic and hydrothermal tourmalines are attributed to the assimilation of the country rock by the magmatic hydrothermal system the six types of tourmaline exhibit variable 11b values ranging from 8 7 to 21 2 tur m1 shows the highest 11b values of 15 1 to 21 2 and tur v2 yields the lowest values ranging from 8 7 to 5 4 the boron probably came from two sources with different isotopic compositions one with high positive 11b values and the other with negative 11b values magmatic hydrothermal fluids could have provided isotopically light boron for hydrothermal tourmalines whereas the heavy boron in magmatic tourmaline was probably derived from marine carbonates that are widespread in the study area the magma related to the mineralization and the one containing magmatic tourmaline may have experienced different degrees of interaction with wall rocks resulting in the diversity of 11b values in hadamiao tourmaline

boron isotope variations in tourmaline from hydrothermal ore deposits a review of controlling factors and insights for mineralizing systems abstract tourmaline group minerals are typically the predominant host of boron in hydrothermal mineral deposits boron is a fluid mobile element whose isotopic composition reflects many factors that are relevant to understanding mineralizing processes including fluid source s fluid rock interaction and formational temperature a new compilation of 2622 published 11b values for tourmaline from diverse types of hydrothermal ore deposits is presented here with the focus 2215 analyses on seven main types porphyry cu mo au deposits granite related sn w deposits iocg deposits orogenic au deposits stratabound vms and sedex deposits and sediment hosted u deposits the total range of 11b values for the seven types is 26 8 to 35 0 four granite sn w orogenic au stratabound vms and sedex have median 11b values close to the continental crustal average of about 10 the median values for iocg and porphyry cu mo au deposits are higher 3 9 and 2 1 respectively whereas sediment hosted u deposits have distinctly high 11b median 25 3 importantly a considerable range of 11b values exists for tourmaline within each deposit type the smallest 17 8 for granite sn w deposits and the largest 48 0 for iocg deposits the boron isotope variations in tourmaline from different deposits are suggested reflect three levels of controlling factors and how these factors operated is illustrated with selected number of case studies the primary factor is the composition of the boron source secondary effects relate to fluid tourmaline fractionation equilibrium or rayleigh there are commonly also tertiary factors that depend on evolution of the specific deposit these include fluid mixing changing water rock ratio and or depositional temperature influences of other boron bearing minerals and where relevant post ore metamorphism separating the effects of these factors is rarely possible from boron isotopes alone however the growth of multi isotope studies of tourmaline and coexisting phases such as mica as well as developments in modelling experimentation of boron isotopes and element partitioning suggest that this limitation will be overcome

biochronology of spanish quaternary small vertebrate faunas abstract thousands of fossils of small vertebrates are recorded in one of the most complete stratigraphic sequences of the continental european pleistocene in the sierra de atapuerca this sequence with a few interruptions spans the last 1 5 million years the stratigraphic series is recorded in six karstic cavities in the sierra de atapuerca from the oldest record to the most modern one these are the sima del elefante gran dolina galeria zarpazos sima de los huesos el portalon and el mirador the faunal successions of continental microvertebrates have made it possible to divide the atapuerca sequence into 7 faunal units atapuerca faunal units ata fus which are based on the first and last local appearances of taxa lo ho the spanish quaternary small vertebrate faunas are grouped into 5 distinct biozones from the oldest to the most recent allophaiomys pliocaenicus allophaiomys lavocati allophaiomys chalinei iberomys brecciensis and iberomys cabrerae these are calibrated with radiometric and palaeomagnetic dating allowing the proposal of a continental biochronological scale for the pleistocene of the iberian peninsula

reassessing the age of atapuerca td6 spain new paleomagnetic results we carry out a new paleomagnetic study across stratigraphic layer td7 of gran dolina site atapuerca and reassess the existing absolute ages thermoluminescence electron spin resonance obtained at this site the new and more detailed magnetostratigraphic record of the matuyama brunhes boundary combined with absolute ages enables further constraint on the age of the underlying human bearing level or aurora stratum paleomagnetism of the studied silts and sandstones reveals stable dual polarity characteristic remanent magnetization directions a new normal magnetic polarity short interval is found at several consecutive sampling localities in the upper part of td7 providing a new ante quem date for the human bearing sediments of 0 9 ma possibly formed during mis 25

geochronology of the medium to high grade metamorphic units of the peloritani mts sicily the peloritani mountains are a fragment of an orogen variably attributed to the alpine or hercynian orogeny on the basis of 39ar 40ar u pb and rb sr dating the main metamorphism of the two medium high grade metamorphic units the mela and aspromonte units and most of the thrusting responsible for stacking the orogenic edifice are seen to be hercynian the main thrusting of the aspromonte unit over the lower grade units took place at 301 2 ma brittle deformation during tertiary reactivation of hercynian thrust planes did not generate any rejuvenation of white micas in the studied sector our dataset shows a great complexity and we propose to unravel it by considering different levels of information to first order the mela and aspromonte units differ in their metamorphic paths and their geochronological evolution the mela unit shows generally younger ages carboniferous than the aspromonte unit and unlike the latter was extensively retrogressed in greenschist facies the aspromonte unit is itself geochronologically heterogeneous proterozoic ages are preserved both in titanite and in amphibole relics of one tectonic subunit devonian to carboniferous amphibole ages are found in different other subunits tertiary overprint is minor and spatially limited we propose to consider the chronologically heterogeneous subunits as accreted pre hercynian terranes amalgamated late during the hercynian orogeny micas in both units give scattered mesozoic 39ar 40ar and rb sr ages with evidence for heterochemical mica generations we interpret them as a result of widespread hydrothermal circulation event s tertiary overprint is generally absent with the exception of a small area near messina where biotite and muscovite underwent a complex recrystallisation history in the interval between 48 and 61 ma

pollen analytical biostratigraphy of the last five climatic cycles from a long continental sequence from the velay region massif central france in the volcanic region of velay massif central france lake sediment sequences derived from maar craters situated close to one another ribains praclaux and lac du bouchet have been correlated on the basis of tephrostratigraphical analyses this has enabled the construction of a sequence 2980 pollen spectra that begins during the glaciation preceding the holsteinian and ends in the present this sequence covers the period from 450 ka i e from the end of marine oxygen isotope stage 12 to the present time and includes five climatic cycles the study of a second core from the praclaux site completed the long velay sequence the biostratigraphy of the whole sequence is described in detail and illustrated by a synthetic and simplified pollen diagram thirteen temperate forest episodes interglacials or interstadials and as many cold periods glacials or stadials are defined each temperate episode is characterised by particular forest development and vegetation dynamics and all of them with the exception of the holocene begin and end with a pinus forest the vegetation dynamics observed during the holocene resemble more closely those recorded during the interstadials than during the interglacials copyright 2000 john wiley sons ltd

dynamics of formation of ferromanganese nodules in the indian ocean abstract the ferromanganese nodule resources of the indian ocean nodule field ionf are second only in the world in terms of metal content and abundance since it was made known by mero 1965 that several trillion tonnes of manganese nodules lay in the world oceans extensive exploration for nodules has been undertaken during the last four decades the possibility of harvesting an inexhaustible supply of nodules from oceans has resulted in formulation of several national and international programs india started her search for ferromanganese nodules in 1982 the investigations have resulted in a comprehensive assessment of manganese nodule resources at the ocean level and on inter basin model for nodule growth albeit with several inaccuracies we list some of the essential requirements for the formation of nodules including the availability of nucleating materials presence of metals in water column and sediment favourable tectonic and physiographic features helpful acoustically transparent sediment water interface low rate of sedimentation presence of nutrient rich bottom water mass and an oxidizing environment we present here an integrated assessment of process of formation of ferromanganese nodules from the ionf which are variable even on scale of metres this assessment will help evaluate the metal potential of these nodules more realistically and the model should bring about a predictive estimate of other nodule bearing areas in the world oceans

the augen gneisses of the peloritani mountains ne sicily granitoid magma production during rapid evolution of the northern gondwana margin at the end of the precambrian abstract the medium to high grade polymetamorphic basement rocks of the peloritani mountains northern sicily include large volumes of augen gneiss of controversial age and origin by means of a geochemical and shrimp zircon study of representative samples the emplacement age of the original granitoid protoliths of the augen gneisses and the most likely processes and sources involved in that granitoid magmatism have been determined u pb dating of three samples from widely spaced localities in the peloritani mountains yielded igneous protolith ages of 565 5 545 4 and 545 4 ma respectively these late ediacaran early cambrian ages are much older than was previously assumed on geological grounds and are typical of the peri gondwanan terranes involved in the geodynamic evolution of the northern gondwana margin at the end of the avalonian cadomian orogeny major and trace element compositions and sr nd isotopic data in combination with zircon inheritance age patterns suggest that the granitoid protoliths of the sicilian and coeval calabrian augen gneisses were generated by different degrees of mixing between sediment and mantle derived magmas the magmas forming the ca 545 ma inheritance rich granitoids appear to have had a significant contribution from partial melting of paragneiss that is the dominant rock type in the medium to high grade peloritanian basement the closeness of the inferred deposition age of the greywacke protoliths of the paragneisses with the intrusion age of the granitoids indicates rapid latest precambrian crustal recycling involving erosion burial metamorphism to partial melting conditions and extensive granitoid magmatism in less than ca 10 ma

petrology and geochemistry of silurian triassic sedimentary rocks in the tongling region of eastern china their roles in the genesis of large stratabound skarn ore deposits abstract this paper describes the petrology and geochemistry of the silurian triassic sedimentary rocks in the tongling area in eastern china aiming to establish a genetic link between different stratabound skarn deposits and sedimentary lithologies the results from this study show that some devonian triassic transitional lithological units with compositions varying between siliceous rock and carbonate especially thinly layered impure carbonate control the distribution of some large stratabound skarn ore deposits in the tongling region interlayer detachment faults in the transitional lithology rocks are particularly important controlling the final locations of the deposits the transitional lithological zones may have also served as source rocks likely providing some ore forming metals to the deposits gypsum evaporites in rocks from carboniferous sources may have supplied some sulphur to the hydrothermal systems five of such transitional lithological units enriched in organic matter are spatially and closely associated with some large stratabound skarn ore deposits in the tongling region suggesting that organic matter may have served as an absorbent or reducing agent during ore formation

a rare garnet tourmaline sillimanite biotite ilmenite quartz assemblage from the granulite facies region of south central massachusetts a rare lithology consisting of garnet tourmaline sillimanite biotite ilmenite quartz has been found within the granulite facies region of south central massachusetts the homogeneous ti rich oxy dravitic tourmaline x mg mg mg fe 0 72 0 77 falls into the alkali group and is similar in composition to lower grade tourmaline found in corresponding metapelitic rocks in maine charge balancing calculations and binary diagrams suggest that like biotite in the region tourmaline has undergone deprotonation by means of the exchange vectors alor 1 oh 1 and tio 2 r 1 oh 2 where r represents fe mg the restriction of a concordant tourmaline rich horizon in otherwise tourmaline free rocks of this granulite facies region suggests that either 1 b released during prograde fluid absent dehydration reactions of muscovite and biotite was locally available in a fluid phase or melt for later crystallization near the peak of granulite facies metamorphism along pathways that provided a conduit for fluid migration or 2 that this is simply a b rich compositional horizon tourmalinite that survived anatexis and granulite facies metamorphism and that records the incipient conditions of tourmaline breakdown and subsequent recrystallization near or post peak metamorphism

formation of laminite deposits in anaerobic dysaerobic marine environments abstract vraconian sediments from the bandol area var southeastern france are characterized by alternations of thin dark laminae in which organic matter is concentrated and light calcareous silt grained laminae the dark laminae black shales are regarded as the result of autochthonous i e in place hemipelagic sedimentation the light laminae calcareous silt result from the partial reworking of turbiditic influxes by deep marine currents comparison with modern marine environments suggests that the vraconian laminite deposits from the bandol area were formed by sedimentation from deep marine circulations the laminated structures formed in a deep marine environment subjected to periodic variations in the physicochemical conditions organic productivity and thus the nature of organic matter the dark laminae were deposited in an anaerobic marine environment in which the organic matter was preserved during the deposition of the light laminae the depositional environment changed to dysaerobic conditions allowing the development of a peculiar benthic fauna responsible for the decreasing organic matter content source rock characteristics of these deposits are inferred from their laminated structure and fine texture coupled with the occurrence of organic rich layers

in situ elemental and boron isotopic variations of tourmaline from the maogongdong deposit in the dahutang w cu ore field of northern jiangxi province south china insights into magmatic hydrothermal evolution abstract in this paper we present a systematic investigation of in situ major trace elements and boron isotopic variations of tourmaline from the maogongdong deposit in the dahutang w cu ore field of northern jiangxi province south china which demonstrates both the magmatic and hydrothermal origin for the formation of the tourmalines the tourmaline occurs mainly in granites pegmatites and quartz veins five types of tourmaline are identified 1 disseminated tourmaline in the pegmatites tur p type 2 isolated and disseminated tourmaline clots in the granites tur r1 type 3 typical anhedral quartz tourmaline nodulars in the granites tur r2 type 4 tourmaline clots in quartz tungsten sulfide veins tur q1 type 5 euhedral needle columnar tourmaline crystals in quartz or quartz sulfide veins tur q2 type these tourmalines mostly fall into the alkali group representing schorl dravite solid solution series petrography and chemical discrimination diagrams suggest that the tur p tur r1 and tur r2 are of magmatic origin and the tur q1 and tur q2 are of hydrothermal origin hydrothermal tourmalines have higher mg mg fe ratios higher li be sn rb co sr v pb zn ni contents and lower na na ca ratios lower nb ta contents than the magmatic tourmalines the tur p show negative eu anomalies and their ree patterns are equivalent to the muscovite granite the eu anomalies in tur r1 and tur r2 change from negative to positive compared with magmatic tourmalines tur q1 and tur q2 exhibit more pronounced positive eu anomalies and a majority of the tur q1 and tur q2 have higher ree contents tourmalines from the maogongdong deposit have a b isotopic composition range from 17 9 to 12 3 the average 11b values of the tur p tur r1 and tur r2 are 13 8 14 8 and 14 5 respectively tourmalines in early hydrothermal veins have similar 11b values average 14 6 while the tourmalines in later hydrothermal veins have slightly lower 11b values average 16 5 boron isotopic variations of tourmaline are controlled by temperature rayleigh fractionation and external fluid

trace element systematics of tourmaline in pegmatitic and hydrothermal systems from the variscan schwarzwald germany the importance of major element composition sector zoning and fluid or melt composition article an extensive data set on the compositional variation of tourmaline from granitic pegmatites from migmatitic gneisses and from various types of hydrothermal veins from the schwarzwald germany is provided the investigated tourmalines are members of the alkali and x vacant groups representing mostly dravite schorl solid solutions with some analyses belonging to the foitite mg foitite series oxygen isotope data on quartz tourmaline pairs indicate formation temperatures between 550 and 350 c for most of the quartz tourmaline veins most of the tourmalines show strong sector zonation fractionating certain major e g na mg minor e g ti ca and trace elements e g sr pb ree among the different crystallographic sectors of the crystals we conclude that comparison of tourmaline compositions for petrogenetic interpretations must be based on the concentrations in the neutral a sector in order to eliminate the effects of intra crystalline fractionation most trace element contents vary over several orders of magnitude with median concentrations generally be tween 0 1 and 10 g g the highest concentrations are found for zn v sr sc sn and li median concentrations of several tens to hundreds of g g whereas very low median concentrations b0 1 g g were found for u th bi tl and cs the concentration of several trace elements e g sr ree co correlates with the major element composition of the tourmaline which implies potential crystal chemical effects on their incorporation conse quently the general assumption that tourmaline is a passive monitor for the chemical compositions of the melts or fluids from which it crystallizes has to be questioned nevertheless our study demonstrates that the trace element composition of tourmaline allows to distinguish between geochemically distinct fluid sources and the trace element composition of tourmaline may therefore be used to unravel the chemical complexity of granite related hydrothermal systems

the influence of sediment recycling and basement composition on evolution of mudrock chemistry in the southwestern united states this paper reports systematic changes in mudrock composition through time on a single con tinental cmstal block the changes reflect both sediment recycling processes and changes through time in the composition of crystalline material being added to the sedimentary system and are related to tectonic evolution as the block matures from a series of accreted arc terranes to a stable craton the major and trace element distributions reflect different aspects of the provenance of the mudrocks in this study major elements record sediment recycling processes as well as changing proportions of sedi mentary and first cycle source rocks with the exceptions of kzo which tends to increase and sioz and a o3 which show no trend most major oxides tend to decline in relative abundance in younger mud rocks patterns shown by the index of compositional variability fe03 kro naao cao mgo mno tiojialro and by k20 a1203 indicate that the major oxide trends are due to decreasing proportions of nonclay silicate minerals and a concomitant increase in the proportion of clay minerals probably due to decreasing input of first cycle detritus coupled with recycling of sedimentary material excursions from progressive trends marked by increases in mgo k20 and cao reflect episodes of large scale input of nonclay first cycle minerals from crystalline source rocks due to large scale basement uplift the chemistry of low solubility trace elements in contrast is not sensitive to recycling effects and reflects the composition of first cycle input incompatible elements are progressively enriched relative to compatible elements in younger mudrocks and values for chondrite normalised rare earth elements also increase in addition the eu anomaly becomes systematically more negative in younger samples these trends cmnot be explained by diagenetic or weathering processes and therefore indicate that the proportion of fnc tionated granitic first cycle detritus being added to the sedimentary system becomes greater with time these results confirm the importance of tectonic setting in controlling mudrock chemistry and also demonstrate that there is a dynamic relationship between the tectonic evolution of a continental block and the composition of its sedimentary mantle

an attempt at correlation between the velay pollen sequence and the middle pleistocene stratigraphy from central europe abstract long continuous lacustrine sequences constitute on the continent a precious tool for coupling the long term continental environmental changes with deep sea and ice core records using the count from the top method moreover they can contribute to long distance correlation on the continent itself and thus help to classify discontinuous sedimentary records palynostratigraphical correlation is proposed here between the velay long sequence and the late middle pleistocene series from central europe with special attention to temperate episodes the similarities between the praclaux and the holsteinian interglacial suggest that they are both contemporaneous with marine isotopic stage mis 11 even if absolute dates are still divergent the evidence of two major warm periods with an interglacial type of vegetation between the holsteinian and the eemian is confirmed by the velay record

strong continentality and effective moisture drove unforeseen vegetation dynamics since the last interglacial at inland mediterranean areas the villarquemado sequence in ne iberia abstract few continental palaeoenvironmental sedimentary sequences from southern europe are long enough to span the last interglacial period marine isotopic stage mis 5 the last glacial cycle mis 4 to 2 and the holocene el canizar de villarquemado north eastern iberian peninsula is an exceptional sedimentary lacustrine sequence spanning the last ca 135 000 years of environmental change in an area of inland iberia characterized by mediterranean climate with strong continentality we present a multiproxy study which combines palynological sedimentological and geochemical analyses framed by an independent robust chronology hydrological and climate evolutions were reconstructed by sedimentological and geochemical proxies development of wetlands and shallow carbonate lakes support relatively humid conditions during mis 6 till the onset of mis 4 and during the holocene palaeohydrological conditions were drier during mis 5 dominance of peat environments than during the holocene more frequent carbonate producing lakes sedimentological evidence indicates extremely arid conditions during mis 3 with greater activity of alluvial fans prograding into the basin sedimentary facies variability highlights a large environmental and hydrological variability during mis 2 and a rapid humidity response to the onset of the holocene compared to classic mediterranean sites we found novel pollen assemblages for the end of mis 6 and mis 5 indicating that the vegetation cover was essentially represented by sustained high proportions of continentality adapted taxa dominated by juniperus during the relatively humid conditions since mis 6 till the onset of mis 4 higher evapotranspiration in inland iberia would have increased during periods of higher seasonal insolation maxima impeding soil development and the usual mesophyte expansion during interglacials observed in other mediterranean areas four main periods of forest development occurred in villarquemado during mis 5e mis 5c mis 5a and the holocene secondary peaks occurred also during mis 3 during colder but still relatively humid mis 4 junipers and mediterranean taxa disappear but some mesophytes and cold tolerant species persisted and pinus became the dominant tree up to modern times pollen assemblages and geochemical data variability suggest a dominant control of seasonality and the impact of north atlantic dynamics both during mis 5 cold events c18 c24 and full glacial conditions he and d o interstadials at millennial scales steppe herbaceous assemblages dominated during the extremely arid conditions of mis 3 and pines and steppe taxa during glacial period mis 2 villarquemado sequence demonstrates that the resilient behaviour of conifers in continental areas of inland southern european regions is key to understand the glacial interglacial vegetation evolution and to evaluate scenarios for potential impacts of global change

chemical and boron isotopic composition of hydrothermal tourmaline from the panasqueira w sn cu deposit portugal abstract tourmaline is a locally abundant hydrothermal mineral in the wallrocks surrounding the w sn cu mineralized veins in the panasqueira deposit portugal and a minor phase within the veins themselves tourmaline chemical and boron isotope compositions have been determined from three settings 1 pervasive fine grained tourmalinization zones in wallrocks within 10 cm of the veins 2 coarser tourmaline in wallrock hosted fault zones and 3 needle shaped tourmaline from late stage vugs in the quartz veins all tourmalines from panasqueira have ferromagnesian compositions with significant octahedral aluminum contents and variable x site vacancies tourmaline compositions show significant chemical variations at the grain and sample scale but are homogeneous on the deposit scale tourmaline is typically optically and chemically zoned showing significant increases in fe and f and decrease in mg ca and al from core to rim moreover as a general trend al increases and mg decreases with proximity to the vein contact the observed chemical variation seems to have been controlled mainly by the vectors femg 1 x alna 1 r2 1 x al oh na 1 r2 1f 1 r2 oh f al 1o 1 and x al2o na 1 r2 2 oh f 1 the total range in tourmaline 11b values from the panasqueira w sn cu deposit is from 3 7 to 12 7 including tourmaline from the three settings the calculated b isotope composition of the hydrothermal fluid based on the average tourmaline composition of 9 and an estimated alteration temperature in the wallrocks based on ti in quartz thermometry of 500 c is 7 1 this isotopic composition is permissive of a boron source from local metasediments or an s type granite but the high boron concentration in the wallrocks with 50 vol tourmaline along with the typical element association of panasqueira w sn f nb ta rb makes a granitic source more likely late stage tourmaline needles in vugs within the mineralized veins show the same patterns and ranges in both chemical and boron isotope composition suggesting that exsolved magmatic fluids were injected in at least two pulses the variations in chemical and boron isotopic compositions of tourmaline combined with estimates from ti in quartz thermometry suggest that hydrothermal ore formation is associated with fluid cooling and geochemical fluid rock interactions

uranium thorium isotopes and transition metal fluxes in two oriented manganese nodules from the central indian basin implications for nodule turnover transition metal fluxes to the top and bottom of two oriented manganese nodules ss 657 and sk 176 were determined by combining radiochemical and geochemical analyses distinct differences in transition metal fluxes 230th contents 230th232th and mnfe ratios and silicate mineralogy in the top and bottom of nodule ss 657 suggest that since the time of inception of oxyhydroxide accretion 1 m y b p it has been growing with a fixed orientation on the seafloor in nodule sk 176 in contrast nearly uniform accumulation rates 230thexc and 230thexc232th extrapolated to surface activities transition metal fluxes and increasing diagenetic influence outwards in the top and bottom are thought to be suggestive of rotation of the nodule several times over time intervals which are smaller than the time resolution involved in u th isotope dating techniques

strata bound fe co cu au bi y ree deposits of the idaho cobalt belt multistage hydrothermal mineralization in a magmatic related iron oxide copper gold system mineralogical and geochemical studies of strata bound fe co cu au bi y rare earth element ree deposits of the idaho cobalt belt in east central idaho provide evidence of multistage epigenetic mineralization by magmatic hydrothermal processes in an iron oxide copper gold iocg system deposits of the idaho cobalt belt comprise three types 1 strata bound sulfide lenses in the blackbird district which are cobaltite and less commonly chalcopyrite rich with locally abundant gold native bismuth bismuthinite xenotime allanite monazite and the be rich silicate gadolinite y with sparse uraninite stannite and bi tellurides in a gangue of quartz chlorite biotite muscovite garnet tourmaline chloritoid and or siderite with locally abundant fluorapatite or magnetite 2 discordant tourmalinized breccias in the blackbird district that in places have concentrations of cobaltite chalcopyrite gold and xenotime and 3 strata bound magnetite rich lenses in the iron creek area which contain cobaltiferous pyrite and locally sparse chalcopyrite or xenotime most sulfide rich deposits in the blackbird district are enclosed by strata bound lenses composed mainly of cl rich fe biotite some deposits have quartz rich envelopes whole rock analyses of 48 co and or cu rich samples show high concentrations of au up to 26 8 ppm bi up to 9 16 wt y up to 0 83 wt rees up to 2 56 wt ni up to 6 780 ppm and be up to 1 180 ppm with locally elevated u up to 124 ppm and sn up to 133 ppm zn and pb contents are uniformly low 821 and 61 ppm respectively varimax factor analysis of bulk compositions of these samples reveals geochemically distinct element groupings that reflect statistical associations of monazite allanite and xenotime biotite and gold detrital minerals chalcopyrite and sparse stannite quartz and cobaltite with sparse selenides and tellurides significantly cu is statistically separate from co and as consistent with the general lack of abundant chalcopyrite in cobaltite rich samples paragenetic relations determined by scanning electron microscopy indicate that the earliest y ree be mineralization preceded deposition of co cu au and bi allanite xenotime and gadolinite y commonly occur as intergrowths with and inclusions in cobaltite the opposite texture is rare monazite in contrast forms a poikiloblastic matrix to cobaltite and thin rims on allanite and xenotime reflecting a later metamorphic paragenesis allanite and xenotime also show evidence of late dissolution and reprecipitation forming discordant rims on older anhedral allanite and xenotime and separate euhedral crystals of each mineral textural data suggest extensive deformation of the deposits by folding and shearing and by pervasive recrystallization all during cretaceous metamorphism sensitive high resolution ion microprobe u pb geochronology by aleinikoff et al 2012 supports these paragenetic interpretations documenting contemporaneous mesoproterozoic growth of early xenotime and crystallization of megacrystic a type granite on the northern border of the district these ages are used together with mineralogical and geochemical data from the present study to support an epigenetic iocg model for fe co cu au bi y ree deposits of the idaho cobalt belt a sulfide facies variant of iocg deposits is proposed for the blackbird district in which reducing hydrothermal conditions favored deposition of sulfide minerals over iron oxides this new model includes mesoproterozoic vein mineralization and related fe cl metasomatism that formed the biotite rich lenses a predominantly felsic magmatic source for metals in the deposits given their local abundance of y rees and be and a major sedimentary component in the hydrothermal fluids based on independent sulfur isotope and boron isotope data for sulfides and ore related tourmaline respectively

a new middle pleistocene marine oxygen isotope stage 6 cold herpetofaunal assemblage from the central iberian peninsula manzanares valley madrid middle pleistocene sites that document glacials are relatively rare in the iberian peninsula and as such the composition of cold small vertebrate assemblages is almost unknown in southwestern mediterranean europe the archaeological site estanque de tormentas de butarque h 02 in villaverde madrid in central spain recently attributed to marine oxygen isotope stage mis 6 provides new data on cold small vertebrate assemblages quantitative climate reconstruction and habitat weighting methods applied to the herpetofaunal assemblage reconstruct the terrestrial climatic and environmental conditions that prevailed in central spain during the penultimate glacial mis 6 during mis 6 the climate was colder 3 0 c and slightly wetter 122 8 mm than present in the study area this confirms that temperature variations were not extreme and precipitation was sufficient in southern mediterranean europe for the persistence of temperate trees paleoenvironmental reconstruction suggests a large representation of dry environments on the overlying plateau together with a probable corridor of humid meadows and woodlands along the river where the site is located

boron isotope systematics of marine sediments abstract boron contents and boron isotopic compositions were determined for modern and ancient permian to miocene marine sediments including pelagic clay calcareous ooze siliceous ooze and neritic clay sediments 11b values of modern marine sediments range from 6 6 to 4 8 isotopic variation is controlled by the simple mixing of four major constituents detritus of continental origin marine smectite biogenic carbonates and biogenic silica detritus of continental origin with an average 11b value of 13 to 8 is the low 11b end member constituent of marine sediments and its boron is largely controlled by the concentration of illite which originates from wind or fluvial transport marine smectite biogenic carbonate and biogenic silica on the other hand represent the high 11b end members with 11b values of 2 3 to 9 2 8 0 to 26 2 and 2 1 to 4 5 respectively these high 11b values are the result of the equilibrium uptake of boron from seawater spatial variations in boron isotopes in the pacific sediments are essentially due to the distribution of the above four constituents although ancient argillaceous sediments shale and slate have boron contents that are identical with those of modern equivalents boron contents of limestone and chert are distinctly lower than those of modern calcareous and siliceous oozes ancient marine sediments have systematically lower 11b values 17 0 to 5 6 than those of the modern sediments the lower 11b values can be caused by diagenesis which induces 1 preferential removal of high 11b boron in calcium carbonate and silica during recrystallization and 2 boron isotopic exchange in the course of the smectite illite transition the observed boron isotopic compositions of ancient argillaceous sediments are distinctly different from those of fresh and altered morb therefore boron isotope systematics will be useful in identifying components from the descending oceanic slab involved in the formation of island arc magma and in investigating mantle crust recycling through subduction processes

new palaeoenvironmental and palaeoclimatic reconstructions for the middle palaeolithic site of cuesta de la bajada teruel eastern spain inferred from the amphibian and squamate reptile assemblages abstract in the eastern iberian peninsula the archaeological site of cuesta de la bajada teruel spain has produced some of the earliest evidence of middle paleolithic stone tool traditions together with evidence of equid and cervid carcasses defleshed by hominins based on the numerical age of 317 240 ka derived from osl esr and aar dating methods for the lower part of the cuesta de la bajada sedimentological sequence level cb3 as well as the biochronological inferences for the small and large mammal associations the site can be attributed to marine isotope stage mis 8 or the end of mis 9 as amphibians and reptiles have precise environmental and climatic requirements and do not differ at species level from the extant herpetofauna of the iberian peninsula they can contribute to the reconstruction of the landscape and climate in this paper the fossil amphibians and squamate reptiles from cuesta de la bajada are studied for the first time the mutual ecogeographic range and habitat weighting methods were applied to the herpetofaunal assemblages to estimate quantitative data for the landscape and climate reconstructions the climate is shown to have been colder and wetter than today in the interior of eastern spain with mean annual temperature up to 2 5 c lower and mean annual precipitation slightly higher than at present the monthly climatic reconstruction shows differences in the distribution of precipitation over the course of the year with more abundant precipitation from late autumn to spring i e from october to may and more or less similar precipitation to today during the summer months july and august this suggests there was stronger rainfall seasonality between winter and summer than currently occurs the paleoenvironmental reconstruction based on the herpetofaunal assemblage depicts a poorly forested 15 20 patchy landscape with a large representation of dry meadows and scrubland habitats together with well evidenced aquatic habitats these reconstructions are consistent with other proxies recovered at cuesta de la bajada pollen small and large mammals as well as other european mis 8 9 paleoclimatic records we can thus correlate levels cb2 and cb3 with the later part of mis 8 265 257 ka or with a humid fluctuation within the mis9b 303 290 ka it is also possible to provide a new description of the environmental and climatic conditions that occurred in inner spain during a cold period of the late middle pleistocene

the ciw index a new chemical index of weathering abstract a new chemical index of weathering that can be applied to modern soils and precambrian paleosis is proposed ciw al2o3 the value of this index increases as the degree of weathering increases and the difference between ciw index values of the silicate parent rock and soil or sediment reflects the amount of weathering experienced by the weathered material

investigating the mid brunhes event in the spanish terrestrial sequence in the mediterranean area which is climatically stressed by limited water resources and extremes of heat climate variations are known to play a crucial role in the ecosystems and environment investigating how climate has changed in the past may help us to understand how it may change in the future and its consequences on temperature and water resources the gran dolina sequence north central spain provides a unique long paleontological and archaeological record spanning the mid brunhes ca 450 ka climatic transition a fossil amphibian and squamate based reconstruction of temperature and precipitation shows marked peaks that have been related to various interglacial peaks in accordance with numeric dates and paleomagnetic and biochronological data an analysis of climate and herpetofaunal assemblage changes during the interglacial periods reveals that 1 post mid brunhes event mbe interglacials were warmer than pre mbe interglacials 2 pre mbe interglacials were warmer than present day and 3 there were lower levels of rainfall in post mbe interglacials than in pre mbe interglacials the climate trend in the mediterranean area was found to be congruous with global climate changes as reconstructed from ice and sea surface temperature records over the past million years

the continental record of marine isotope stage 11 middle pleistocene on the iberian peninsula characterized by herpetofaunal assemblages marine isotope stage mis 11 in iberia is documented at three main acheulean archaeological sites gran dolina burgos atapuerca aridos 1 madrid and ambrona soria as the amphibians and reptiles recovered as fossils from these sites are not extinct and their ecology can be directly studied mutual climatic range and habitat weighting methods have been applied to the herpetofaunal assemblages to estimate climatic and environmental parameters during mis 11 compared with today mean annual temperature varies from 2 7 to 0 3 c and mean annual precipitation varies from 311 7 to 74 4 mm suggesting in accordance with the numerical dates for each locality a progressive decrease in temperature and rainfall from the fully interglacial conditions of mis 11c to the end of mis 11 the presence of woodland areas is also well substantiated throughout the duration of mis 11 at least during the interglacial and interstadial periods

early pleistocene palaeoenvironments at the time of the homo antecessor settlement in the gran dolina cave atapuerca spain hominin remains unearthed from level td6 2 of gran dolina have been dated to slightly more than 0 8 ma owing to the importance of this discovery every effort is being made to reconstruct the environment where these hominins once lived in this paper the mutual climatic range and habitat weighting methods are applied to the herpetofaunal assemblages in order to estimate climatic and environmental parameters td6 2 is thus characterized by a warm and humid climate mean annual temperature is estimated at 2 1 c higher than at present in burgos with a greater increase in temperature during summer 3 1 c than during winter 1 4 c rainfall was more abundant than at present 407 2 mm occurring as at present principally during spring and autumn humid meadows and riparian woody habitats were common the association between warm climatic conditions and the not fully developed forest suggests that the several episodes of high intensity occupation in td6 2 may correspond to a recolonization by homo antecessor of the high inland plateaus of the iberian peninsula from the mediterranean seashore using the ebro valley as a savannah type corridor after a cold glacial period copyright 2013 john wiley sons ltd

mineralogy geochemistry and geological significance of tourmaline rich rocks from the paleozoic cinco villas massif western pyrenees spain tourmaline rich rocks associated with clastic metasedimentary rocks of carboniferous age occur in the cinco villas massif western pyrenees three types of tourmaline rich rocks were distinguished 1 fine grained stratiform tourmaline rich rocks which are associated with carbonaceous metapelites tr1 2 stratabound tourmaline rich rocks associated with metapelites in the contact aureole of the aya granitoid pluton tr2 3 stratabound to massive tourmaline rich rocks associated with psammopelites in contact with granites and pegmatites tr3 tourmalines belong to the schorl dravite solid solution series and have a wide compositional range from nearly end member dravite for tr1 tourmalines to schorl for tr3 tourmalines tr2 tourmalines have intermediate compositions the fe fe mg typically varies between 0 02 and 0 55 increasing from tr1 to tr3 the tr1 tourmalines commonly display a discontinuous chemical zoning with fe rich green cores 8 8 5 feo and mg rich colorless rims 10 11 mgo in contrast crystals that exhibit fine growth lamellae appear to lack significant chemical zoning oxygen and hydrogen isotope compositions also reveal major differences between tr1 and tr3 tourmalines the former displaying heavier 18o values 17 7 19 and d values 35 to 42 than tr3 tourmalines 11 to 13 and 47 to 76 respectively the tr2 tourmalines show intermediate values of 11 3 to 14 6 for 18o and 40 to 55 for d linear and continuous chemical variations obtained for major and trace elements of the whole rocks reflect mixing between clay rich and quartz rich end members indicative that some tourmaline rich rocks contain a significant detrital component chondrite normalized ree rare earth element patterns of tourmaline rich rocks are similar to those of surrounding unaltered clastic metasediments except for some tr1 rocks which are characterized by low contents of ree mass balance calculations show that tourmaline forming processes plus metamorphism led to mass and volume changes at mesoscopic scales 10 for the tr1 tourmalinites silicon fe mn and ree elements were partially lost from sedimentary rocks whereas mg and particularly b were added to pelitic sediments available data nevertheless do not allow an assessment of the boron source formation of the tr1 tourmaline rich rocks probably was the net result of several processes including direct precipitation from b rich hydrothermal fluids or colloids early diagenetic reactions of carbonaceous pelitic sediments with these fluids and subsequent recrystallization during regional metamorphism the tr2 tourmaline rich rocks mainly developed by metamorphic recrystallization of tr1 tourmaline rich rocks and veins adjacent to pegmatites and granitic rocks tr3 are the result of boron metasomatism the primary boron having been recycled from stratiform tourmalinites during regional metamorphism and magmatism

boron isotopic composition of tourmaline from massive sulfide deposits and tourmalinites boron isotope ratios 11b 10b have been measured on 60 tourmaline separates from over 40 massive sulfide deposits and tourmalinites from a variety of geologic and tectonic settings the coverage of these localities is global 5 continents and includes the giant ore bodies at kidd creek and sullivan canada broken hill australia and ducktown usa overall the tourmalines display a wide range in 11b values from 22 8 to 18 3 possible controls over the boron isotopic composition of the tourmalines include 1 composition of the boron source 2 regional metamorphism 3 water rock ratios 4 seawater entrainment 5 temperature of formation and 6 secular variations in seawater 11b the most significant control appears to be the composition of the boron source particularly the nature of footwall lithologies variations in water rock ratios and seawater entrainment are of secondary importance the boron isotope values seem especially sensitive to the presence of evaporites marine and non marine and carbonates in source rocks to the massive sulfide deposits and tourmalinites

refining upon the climatic background of the early pleistocene hominid settlement in western europe barranco leon and fuente nueva 3 guadix baza basin se spain abstract the early pleistocene sites of barranco leon and fuente nueva 3 guadix baza basin se spain have yielded thousands of mode 1 or oldowan lithic artifacts both sites and one tooth in layer d formerly 5 of barranco leon today considered to be some of the earliest evidence of humans in western europe at ca 1 2 1 5 ma previous quantitative paleoclimatic reconstructions based on herpetile assemblages indicated that during the formation of these two sites the mean annual temperature and mean annual precipitation were higher than they are now in the southeastern iberian peninsula with lower continentality here we propose new climatic reconstructions where the mean monthly temperature and precipitation and the difference between the four driest months and the four rainiest months are estimated climatograms are built in order to specify the distribution and variation of temperature and precipitation during the year and the aridity indices of gaussen lautensach mayer dantin revenga and de martonne are used to characterize ombroclimatic differences according to these new climatic parameters rainfall distribution through the year shows considerably higher precipitation in every season except summer and early autumn which remain drier and thus consistent with a mediterranean climate pattern no change is observed in the duration of the aridity period which remains four months long however the value of the aridity index of de martonne is higher than 20 subhumid climate in barranco leon and fuente nueva 3 whereas today it is lower than 20 semi arid climate suggesting major changes in the ombroclimatic type these results yield a more precise scenario for the paleoclimatic conditions that prevailed during the late early pleistocene in the guadix baza basin and permit us to contrast the ages obtained from numerical dating and biochronology the very warm and humid climate reconstructed for both barranco leon and fuente nueva 3 suggests that in accordance with the numerical dating these two sites are contemporaneous with the particularly warm interglacial peaks of marine isotope stages 43 49 i e between 1 35 and 1 47 ma the similarity between reconstructed climates the high overlap between their estimated precipitation and between the difference of the driest from the rainiest season suggest that these sites may correspond to the same part of a climatic glacial interglacial cycle but because the evolutionary degree of the rodent mimomys savini shows a slightly more derived state for fuente nueva 3 than for barranco leon i e a short chronological difference between the two sites they may correspond to two consecutive warm interglacial peaks

local variability of manganese nodule facies on small abyssal hills of the central pacific basin abstract local variability of manganese nodule facies and associated sediments were studied around abyssal hills 60 60 km 2 located in the equatorial zone of the central pacific basin small scale variations in nodule occurrence mineralogy chemistry and internal structure are discussed in relation to seismic records and sediment lithology the slow sedimentation rate from the late tertiary to the quaternary appear to have promoted formation of nodules around the abyssal hills although the plio pleistocene hiatus at depths below sediment surface suggests no clear evidence of increased growth of nodules during the period in the area of rapid and continuous sedimentation away from the hill areas nodules are rare probably because of insufficient lifting force for nodules mineralogical and chemical studies reveal that the two principal nodule morphologies smooth and rough surfaces result from preferential deposition of hydrogenous or diagenetic manganese minerals in relation to early diagenesis of surface siliceous sediments regional variability of nodule surface morphology and composition suggests a very local change in sedimentary conditions in space and internal mineral variation suggests changes in sedimentary conditions with time the geological factors controlling the small scale variability of nodule facies seem to be similar to those controlling regional scale variations

carbon isotopic thermometry calibrated by dolomite calcite solvus temperatures abstract the temperature dependence of carbon isotopic fractionations between calcite and graphite and between dolomite and graphite are calibrated by the calcite dolomite solvus geothermometry using marbles collected from the contact metamorphic aureole in the kasuga area central japan the carbon isotopic fractionations 13ccc gr and 13cdo gr systematically decrease with increasing metamorphic temperature the concordant relationships between the fractionations and solvus temperatures are approximately linear with t 2 over the temperature range 400 to 680 c 13ccc gr 5 6 106 t 2 k 2 4 13cdo gr 5 9 106 t 2 k 1 9 these systematic relationships between fractionation and temperature suggest that carbon isotopic equilibria between carbonates and graphite were attained in many cases the equation for the calcite graphite system has a slope steeper than bottinga s 1969 results it is however in good agreement with that of valley and o neil 1981 in the temperature range from 600 to 800 c because of the relatively high sensitivity to temperature these isotopic geothermometers are useful for determining the temperatures in moderate to high grade metamorphosed carbonate rocks

the influence of geological factors on the concentration of boron in australian and canadian coals abstract the concentration of boron in australian and canadian coals determined using atomic emission spectrometry aes inductively coupled plasma spectrometry icp aes and prompt gamma ray spectrometry is summarized in order to assess the variation of b content in coal with respect to rank age geological setting in seam and stratigraphic and the degree of paleosalinity of the coal forming environment this study indicates that no or very complex relations exist between boron and rank subbituminous to anthracite variations of b with ash content for canadian coals of different age devonian to oligocene eocene indicate that the b content of coals is not governed by the age of the coal there is some evidence of variation of b with maceral content in canadian coals particularly as related to the inertinite and vitrinite content of coals the b content of coal seams is sensitive to the environment of deposition with b contents remaining relatively stable and within the range of values designated for each depositional setting however b values may show variation in the same seam laterally due to changes of the environment of deposition and or the enrichment of b by a secondary source the vertical variation of b in a coal bearing section or strata is related to depositional environment and lithology of rock there is often little variation in b content for coal layers as compared to the partings dirt bands the b content of partings in a coal bearing strata may vary greatly as compared to the coal seams after reappraising earlier work and on the basis of more recent studies on australian and canadian coals it is proposed that the following ranges of values for b in coal indicate the degree of marine influence during the early stages of coalification up to 50 ppm b freshwater influenced coals 50 110 ppm b mildly brackish water influenced coals 110 ppm b brackish water influenced coals using these criteria assessments are given for the degree of marine influence on canadian and australian coals

a reconnaissance of the boron isotopic composition of tourmaline abstract a preliminary investigation of the boron isotopic composition of tourmaline from some boron rich associations has been made the results for tourmaline from metasedimentary parageneses n 12 range from 11b 22 to 22 per mil these data mainly fall between the boron isotopic compositions of normal marine sediments with 11b 2 to 5 per mil and seawater with 11b 39 5 per mil tourmaline samples from granitic pegmatites n 6 on the other hand range from 11b 12 to 5 per mil the data provide a rudimentary indication of the range of boron isotopic variation in tourmaline some of the processes leading to this range and some possible geochemical tracer applications

the early middle pleistocene palaeoenvironmental change based on the squamate reptile and amphibian proxies at the gran dolina site atapuerca spain abstract although still ongoing the archaeological and palaeontological excavations in the gran dolina cave sierra de atapuerca burgos every year since 1976 have already revealed a long culturally and palaeontologically rich sequence dated by biostratigraphy esr u series and the palaeomagnetic record at between roughly 1 my and 250 ky gran dolina has one of the longest and most continuous vertical profiles the section 19 m thick divided into 11 stratigraphic levels represents a time span of nearly 700 000 years the gran dolina sequence was partially excavated during a preliminary evaluation of its archaeological and palaeontological richness this excavation known as the gran dolina sondeo south lasted from 1993 to 1999 hominin remains were unearthed in 1994 from level 6 of gran dolina and level 6 was dated to somewhat more than 780 ky based on palaeomagnetic and microfaunal evidence making these the oldest known hominins in europe given the importance of this discovery every effort is being made to reconstruct the landscapes where these hominins once thrived the gran dolina sondeo south tds has furnished a great number of microvertebrate remains and of these around 40 000 bones are attributed to amphibians and squamates the faunal list of the squamates and amphibians of the tds comprises at least 22 species a diversity similar to what exists nowadays in spain triturus sp alytes obstetricans pelobates cultripes pelodytes punctatus bufo bufo bufo calamita hyla arborea rana temporaria rana cf dalmatina rana cf iberica pelophylax ridibunda sp blanus cinereus lacerta s l small sized indeterminate lacertids anguis fragilis natrix natrix natrix maura coronella austriaca coronella cf girondica rhinechis scalaris vipera cf aspis and vipera cf latasti these ectotherm vertebrates show variations in their taxonomic diversity throughout the sequence although they do not differ specifically from the extant herpetofauna of the iberian peninsula they do so in the composition of their taxonomic assemblage when the squamates and amphibians of tds are grouped by habitat categories the habitat weightings method and studied in terms of their vertical evolution throughout the sequence it is possible to follow environmental changes across the early middle pleistocene transition results from the squamate and amphibian studies indicate that the landscape had open habitats in the vicinity of the atapuerca caves throughout the sequence with wet points in the surrounding area open dry microhabitats were more developed during warm periods whereas during cold periods the environment was slightly more humid and wooded these results are compared with studies in small mammals pollen analysis and geomorphology giving a scenario for the palaeoclimatic and palaeoenvironmental changes that occurred during the early to middle pleistocene boundary in atapuerca and hence a scenario for the hominins that once lived in the sierra de atapuerca

climate and environments during marine isotope stage 11 in the central iberian peninsula the herpetofaunal assemblage from the acheulean site of aridos 1 madrid abstract the interglacial episodes of the quaternary period are currently the focus of a great deal of attention within the scientific community primarily because they can help us to understand how the climate of the current interglacial may have evolved without human intervention and to assess the impact of these climate changes on ecological systems in the central iberian peninsula the archaeological site of aridos 1 arganda madrid with numeric dates of 379 7 45 ka obtained by aar for the upper part of the sedimentological unit of arganda i in combination with the evolved state of the small mammals has been chronologically attributed to marine isotope stage mis 11 given the diversified faunal assemblages delivered by the 1976 excavations aridos 1 is probably one of the best terrestrial candidates for an understanding of the climatic and environmental conditions that prevailed in central spain during the mis 11 interglacial in consequence the fossil amphibians and squamate reptiles stored in the collections of the museo arqueologico nacional of madrid have been newly described and quantified in order to apply the mutual climatic range and habitat weighting methods for estimating quantitative data the mediterranean climate is shown to have been warmer and wetter than today in central spain during mis 11 with the mean annual temperature 1 7 c higher and mean annual precipitation 223 9 mm higher than at present the monthly climatic reconstruction shows differences in the distribution of precipitation over the course of the year with more abundant precipitation during the winter months at the beginning of spring and at the end of fall from october to march and less precipitation than today during the summer months and at the end of spring from may to august suggesting stronger rainfall seasonality between winter and summer than currently occurs such climate reconstruction is consistent with other european mis 11 paleoclimatic records the paleoenvironmental reconstruction based on the herpetofaunal assemblage suggests a patchy landscape with a large representation of dry meadows scrubland and rocky habitats together with well evidenced aquatic habitats such open environments during a warm and humid forestal period are seen to be connected with the location of the site in a large river valley where open vegetation would have been partly initiated and certainly maintained by the grazing browsing trampling and tree felling activities of large mammals

interelement relationship in abyssal pacific ferromanganese nodules and associated pelagic sediments abstract by r mode factor analysis and enrichment factor calculations most of the elements in abyssal ferromanganese nodules and associated pelagic sediments excluding common authigenic minerals like apatite barite opal and carbonates are found to be preferentially concentrated in one of the following three major phases aluminosilicates e g al si sc ga cr be na k rb and cs fe oxides e g fe p s v se te as b sn u hg pb ti ge y zr nb pd in rare earths hf th pa pu am ru and bi and mn oxides e g mn tl ag cd mg ca ba ra co ni cu zn mo sb and probably w the specific association of elements with these three phases can be explained by the difference in chemical forms of elements in seawater and by fundamental differences in physicochemical properties e g the ph of zero point of charge and dieletric constant of these three phases

the sedimentary cycle of the boron isotopes abstract marine sediments contain two isotopically distinct components a non desorbable fraction with 11b between 4 3 and 2 8 per mil n 10 and a desorbable component with 11b between 13 9 and 15 8 per mil n 6 the adsorption coefficient k for the uptake of b from seawater by fluvial suspended material mississippi has an experimentally determined value of 1 54 0 05 the associated isotope fractionation factor is 0 974 0 003 empirical values for k determined from the analysis of marine sediments n 6 were between 3 and 4 the amount of b adsorbed onto fluvial suspended material during estuarine mixing is about 9 109 moles yr based on pore water data adsorption experiments and comparative size fraction analyses suspended sediments from the mississippi river vs bottom deposits from the delta there is no evidence for the incorporation of b into detrital sediments at low temperature however the high b content of bauer deep metalliferous sediments must be due to incorporation of seawater b during formation of authigenic silicates the 11b of these minerals is 2 3 per mil hydrothermally altered sediments from dsdp hole 477 guaymas basin gulf of california have variable b contents from 33 ppm similar to the unaltered detritus to 1 2 ppm in the recrystallized material the latter has 11b as low as 9 0 per mil substantially lower than the unaltered material hydrothermal solutions collected from vents adjacent to the hole have boron contents elevated by about a factor of 4 relative to seawater and 11b between 16 5 and 23 2 per mil the b mobilized from the sediments is isotopically fractionated with the fluids being preferentially enriched in the heavy isotope analysis of an oxisol profile developed over granite in the guyana shield showed that boron is partially mobilized during weathering with an isotopic offset of 2 5 per mil between bedrock and soil the observed enrichment of b in shales relative to igneous rocks does not occur during weathering or during exposure to seawater at low temperature incorporation occurs only during burial diagenesis at temperatures greater than about 60 c however the enrichments cannot be attained during a single cycle of primary weathering and burial but must be cumulative over many cycles

towards a middle pleistocene terrestrial climate reconstruction based on herpetofaunal assemblages from the iberian peninsula state of the art and perspectives abstract the pattern of the varying climatic conditions in southern europe over the last million years is well known from isotope studies on deep ocean sediment cores and the long pollen records that have been produced for lacustrine and marine sedimentary sequences from greece italy and the iberian margin however although relative glacial and interglacial intensities are well studied there are still few proxies that permit quantitative terrestrial temperature and precipitation reconstruction in this context fauna based climate reconstructions based on evidence preserved in archaeological or palaeontological sites are of great interest even if they only document short windows of that climate variability because a they provide a range of temperature and precipitation estimates that are understandable in comparison with present climate b they may allow the testing of predicted temperature changes under scenarios of future climate change and c quantitative temperature and precipitation estimates for past glacials and interglacials for specific regions latitudes can help to understand their effects on flora fauna and hominids as they are directly associated with those cultural and or biological events moreover such reconstructions can bring further arguments to the discussion about important climatic events like the mid bruhnes event a climatic transition between moderate warmths and greater warmths during interglacials in this paper we review a decade of amphibian and reptile based climate reconstructions carried out for the iberian peninsula using the mutual ecogeographic range method in order to present a regional synthesis from mis 22 to mis 6 discuss the climate pattern in relation to the mid bruhnes event and the thermal amplitude suggested by these estimates and finally to identify the chronological gaps that have still to be investigated

source composition and distribution of the fluid in the kurile mantle wedge constraints from across arc variations of b nb and b isotopes b and nb concentrations and b isotope composition were determined for lavas covering the entire length of the kurile arc b nb and 11b of these lavas show clear across arc variations in which both are highest at the trench side and continuously decrease as the slab depth increases b nb in the volcanic front lavas 8 25 is significantly higher than those of morb and oib indicating that the mantle wedge is extensively metasomatized by b rich fluid derived from the subducting slab the frontal 11b values are also out of the range of morb and oib and systematic difference exists between northern kurile nk 5 4 0 5 and central and southern kurile csk 4 3 0 3 however these two parameters approach or coincide with mantle values at the most back arc side the 11b and 87sr 86sr linearly correlate with nb b suggesting control by simple mixing of two isotopically homogeneous components that is slab derived fluid and mantle wedge the estimated 11b and 87sr 86sr of the fluid are 7 0 0 6 and 0 70326 0 00005 for nk and 6 3 0 3 and 0 7033 for csk respectively these fluid compositions are consistent with a source constituted by 95 altered oceanic crust and 5 oceanic sediment with the slight difference between nk and csk resulting from the different lithologies of subducting sediments the mantle wedge beneath the kurile arc has b sr and nd isotope compositions identical with morb but shows significantly higher b nb the above trends bear a close resemblance to those observed in the izu arc strongly suggesting their universality in the arc system the across arc decline of b nb observed both in kurile and izu implies that the fluid flux from the slab continuously decreases as the slab depth increases however this relates only to a final stage of slab dehydration since most of the volatile components are lost at the fore arc region in contrast to b k is uniformly enriched across the arc this requires control by a k bearing mineral phase either in the slab phengite or the mantle wedge phlogopite although such a mineral is responsible for only a small part of the whole fluid transport

a long pollen record from lac du bouchet massif central france for the period ca 325 to 100 ka bp ois 9c to ois 5e abstract pollen analysis was carried out on sediments older than the wurm pleniglacial ois 4 in two new sequences h and i derived from the centre of lac du bouchet massif central the inferred vegetation history enables for the first time in france five temperate episodes to be defined which pre date the last interglacial these temperate episodes alternate with episodes during which the changes in vegetation are indicative of glacial climates comparison of these climatic episodes with the oceanic isotope record shows that the pollen record of sequences h and i from lac du bouchet spans the time interval from ois 9c ussel interstadial to ois 5e ribains eemian interglacial in the organic sediments from the amargiers interstadial ois 9a a trachytic layer ar ar dated to ca 275 ka enables a correlation to be established with the upper part of a sequence derived from the nearby praclaux crater the lower part of this sequence being of holsteinian age ois 11c the cross dating of the pollen sequences from lac du bouchet cores h i and d and from praclaux provides a complete record from the massif central southern france of successive glacial and interglacial episodes that span the last ca 400 ka that is the interval from the holsteinian to the holocene

li b rich rhaetian metabauxite tuscany italy reworking of older bauxites and igneous rocks abstract li b rich metabauxite layers occur in two outcrops of talus metabreccias intercalated between norian and liassic marbles in the alpi apuane tuscany italy field evidence petrographical geochemical and paleogeographic paleoclimatologic considerations suggest that bauxitic material was derived from a multistage reworking of late carboniferous early autunian primary deposits now completely removed the identified lithotypes are cookeite rich metabauxite cookeite bearing metabreccia chloritoid schist and chloritoid phyllite the mg content of calcite and the si content of muscovite and mineral assemblages indicate temperatures of 350 380 c pressures of f o 2 values of 10 30 to 10 24 for the alpine metamorphism in comparison with the average mesozoic bauxite of bronevoy et al 1985 the metabauxite is strongly enriched in si k ca mg li b be ni and ce it shows comparable contents of co la eu tb ta and th it is depleted in ga cr v zn mn hf u and is strongly depleted in sr f cu a metabauxite layer shows decreasing abundance of fe and ga from bottom to top with a pattern opposite to that of primary bauxite deposits inverted profile the strong enrichment of li and b is not related to evaporitic conditions since the mgo na 2 o and sr contents are too low and indicator minerals such as dravitic tourmaline albite and scapolite are missing during the permian volcanic products similar to the coeval peralkaline peraluminous rocks of corsica sardinia were widespread in tuscany b li rich minerals were produced by circulation of hot hydrothermal fluids within the permian volcanic rocks during and soon after their emplacement the erosion of such hydrothermal products supplied detrital material to the talus metabreccia

chemical and boron isotopic composition of tourmaline from the conadong leucogranite pegmatite system in south tibet abstract tourmalines occur widely within leucogranites and pegmatites that intrude the leucogranites in the south tibetan plateau morphological and geochemical elemental and boron isotopic studies on these tourmalines are very limited furthermore the tourmaline genetic correlation between the leucogranite and the pegmatite is also unknown in this contribution two types of tourmaline occurrences have been identified in the conadong area south tibet including randomly disseminated tourmaline in leucogranite gt type and radial dendritic or massive tourmaline aggregates in pegmatite dikes that intrude the leucogranite pt type we performed major element and boron isotopic analyses of tourmaline using electron microprobe empa and laser ablation multi collector inductively coupled plasma mass spectrometry respectively the two types of tourmalines are enriched in fe na and al but relatively depleted in ca and mg elements with compositions close to alkali group tourmaline and schorl all the tourmalines are likely the products of equilibrium crystallization and their dominance of na was controlled by the magmatic compositions of their host rocks the gt type tourmalines show a narrow range of 11b values between 9 78 0 81 and 8 53 0 68 with a mean of 8 91 0 18 whereas the pt type tourmalines have significantly lower 11b values than the gt type ranging from 14 02 0 85 to 11 83 0 57 with a mean of 13 31 0 49 these data together with their morphology and petrography indicate that the conadong granitic tourmalines were derived by the melts at the early magmatic stage whereas the pegmatitic tourmalines precipitated from magmatic hydrothermal fluids at the late magmatic stage the variation in boron isotopic compositions 11b 4 4 between the pt and the gt type tourmalines is most likely correlated with their different melt fluid source regions that had distinct sr nd b isotopic compositions

the association of tourmalinite with stratiform scheelite deposits three types of stratiform scheelite deposits are recognised they all commonly have a close spatial association with tourmalinite regional prograde calc silicate rocks in precambrian rift settings commonly contain 100 ppm wo3 with enrichment to 0 5 1 wo3 in retrograde metamorphic assemblages at fold hinges joints faults shears and granite and pegmatite dyke contacts the calc silicate progenitor was probably a impure dolomitic carbonate sediment amphibolite hosted scheelite deposits occur in metamorphosed altered mafic volcanics formed in a narrow rift graben scheelite occurs both as stratiform and stratabound footwall stringer ore which has undergone minor remobilization during tectonism tourmalinites are rarely the host for stratabound quartz scheelite wolframite veins remobilized from the host tourmalinite and associated metavolcanics during tectonism

the indian ocean nodule field petrotectonic evolution and ferromanganese deposits abstract the indian ocean nodule field ionf is significant from several points of view roughly bordered by 10 s to 16 30 s and 72 e to 80 e and located within the central indian ocean basin ciob the field hosts the world s second largest and second high grade manganese nodule deposit after the equatorial nodule belt in the north pacific ocean moreover the crust underlying this field is characterised by unique morphotectonic signatures owing to its formation between 60 and 49 ma under three variable spreading conditions fast intermediate and slow from the indian ocean ridge system iors the nodule field has been surveyed both extensively more than 0 4 million km2 area and intensively comprising of a large geophysical data set and geological sample inventory during the last two decades several morphotectonic features such as seamounts hills ridge normal lineaments and ridge parallel lineations have disturbed the apparently smooth topographic gradient 1 7000 of the seafloor here variations in the rate of spreading and formation of new oceanic crust along the ridge crest during more than one episode of india eurasia collision are imprinted in the ionf based on the nature of the ridge parallel lineations which are related to the rate of crustal accretion the field is divided in to four sectors a b c and d from north to south sectors a and c were formed at a fast rate of spreading 90 95 mm year half rate and sectors b and d were formed at an intermediate 55 mm year and slow 26 mm year rates respectively the predominance of tensional stress in sectors a and c caused asymmetrical flexuring of the seafloor resulting in widely spaced faults and folds with low amplitude and large wavelength in contrast the seafloor flexuring in sector d are closely spaced long symmetrical and of high amplitude the timing and intensity of the collision of india with eurasia is constrained by the variable intensity of these flexures suggesting probably a soft touch at 58 ma and the hard collision at about 51 ma the nodule field hosts several seamounts both as isolated entities and in linear chains which are arranged parallel to the flow lines along the direction of absolute motion of the indian plate the distribution morphology and growth patterns of a majority of these seamounts are related to spreading rate suggesting their formation at the ridge crest however many of the seamounts show more than one stage of growth with local intraplate volcanism contributing to the enlargement of the larger ancient seamounts varieties of volcanics such as tholeiitic basalts spilites ferrobasalts and pumice occur within the ionf the alteration of some of these volcanics has resulted in palagonitisation of the glass and formation of zeolites subsequently during its journey away from the ridge crest to the abyssal areas the crust underlying the nodule field witnessed intraplate volcanism this is evident from the addition of younger rocks at the base of the ancient seamounts inconsistent growth of volcanoes eruption of ferrobasalt corresponding to the areas of high amplitude magnetic zones and presence of volcanogenic hydrothermal materials vhm of 10 ka age these findings collectively hint that the ionf is geodynamically unstable and may have been volcanically active in the recent past during the last 8 ma growth of authigenic ferromanganese deposits in the form of manganese nodules and crusts has occurred in the nodule field the deposits occur at an average water depth of 5000 m the basinal geomorphology intraplate tectonic deformations and volcanic eruptions considerably influence the formation development morphology mineralogy and composition of these deposits the data show that the large seamounts reverse faults and fracture zones fzs supply rock fragments as seeds for the nodule formation the hydrogenous precipitation from the overlying water column is the primary source of metal accumulation in the nodules the secondary relatively weak intraplate eruptions along the base of ancient seamounts or lineaments subsurface igneous activity and diagenetic remobilisation of metals have also played significant role in the growth and enrichment of the deposit based on a large data set we estimate the contribution of various physico chemical parameters and model the probable conditions of formation of the ferromanganese deposits in the ionf the model also hints at the location where the resource exploitation should be rewarding

sm nd and ree characteristics of tourmaline and scheelite from the bjorkdal gold deposit northern sweden evidence of an intrusion related gold deposit the bjorkdal quartz vein hosted gold deposit is located 25 km northwest of skellefte in northern sweden within a paleoproterozoic volcanosedimentary sequence at the margin of a quartz monzodiorite granitoid northeast trending 030 050 quartz veins from the eastern open pit within the bjorkdal deposit contain quartz scheelite tourmaline calcite and sulfides with visible gold vein quartz shows undulatory extinction and sutured margins or is polycrystalline in form features which suggest postcrystallization deformation coarse scheelite crystals 5 mm within the quartz veins are crosscut by thin veins of quartz calcite sulfides and gold the calcite in these crosscutting fractures is variably replaced by biotite or actinolite tourmaline from the quartz veins has low total ree contents 1 chondrite and lree enriched patterns la sm n 2 8 4 5 la yb n 1 8 5 1 with strong positive eu anomalies eu eu 3 9 17 4 in contrast the scheelite has a bell shaped ree pattern enriched in mree but also with positive eu anomalies eu eu 1 4 2 4 the ree pattern of scheelite results from a strong crystallographic effect largely due to the size of the ca site and charge balance sm nd dating of scheelite from the bjorkdal ore yields an age of 1893 34 ma which coincides with a previously suggested age of the host intrusion the end values of the scheelite 1 8 and 87sr 86sr initial ratios of the tourmaline 0 7013 0 7014 are also consistent with derivation of ree and sr in these minerals from the jorn granitoids overall the petrographic geochemical and isotopic data strongly suggest that bjorkdal is an intrusion related gold deposit and that there is no requirement for involvement of external post magmatic hydrothermal fluids

the last 1 35 million years at tenaghi philippon revised chronostratigraphy and long term vegetation trends abstract in addition to being of interest to ancient greek and roman historians the site of philippi ne greece has long been noted in quaternary circles for providing the longest continuous european pollen record spanning the last one million years here the original age model is re evaluated and a new marine terrestrial correlation is proposed an astronomical calibration procedure based on a correspondence between changes in certain vegetation elements and march and june perihelion configurations suggests that the base of the sequence extends back to 1 35 million years ago the revised chronological framework for the tenaghi philippon sequence provides an opportunity to examine the long term behaviour of individual taxa and vegetation trends within the context of global climate changes comparisons reveal a close correspondence between the terrestrial and marine records in terms of orbital and suborbital variability however joint time frequency analysis of the arboreal pollen record shows that the obliquity and eccentricity precession signals persist into the 100 kyr and 41 kyr worlds respectively suggesting the operation of additional climate mechanisms that are independent of high latitude glacial interglacial effects unlike ice core and marine sequences no change in the magnitude of interglacial tree population expansions is observed after the mid brunhes event instead the tenaghi philippon record suggests a major shift in the vegetational composition of interglacials after mis 16 with the establishment of forests of reduced diversity and a modern appearance

late magmatic immiscibility during batholith formation assessment of b isotopes and trace elements in tourmaline from the land s end granite sw england quartz tourmaline orbicules are unevenly distributed in the roof segment of the land s end granite sw england this study shows that the orbicules formed from an immiscible hydrous borosilicate melt produced during the late stages of crystallization and differentiates tourmaline formed by dominantly magmatic and dominantly hydrothermal processes trace elements and boron isotope fractionation can be tracked in tourmaline and create a timeline for crystallization tourmaline from the granite matrix has higher v cr and mg content and is isotopically heavier than the later crystallizing inner orbicule tourmaline overgrowths of blue tourmaline occurring together with quartz showing hydrothermal cathodoluminescence textures crystallized from an aqueous fluid during the very last crystallization and are significantly higher in sr and sn and isotopically heavier tourmaline associated with sn mineralization is also high in sr and sn but has boron isotopic compositions close to that of the magmatic tourmaline and is not formed by the same fluids responsible for the blue overgrowths the ore forming fluids precipitating tourmaline and cassiterite are likely derived from the same magma source as the granite but exsolved deeper in the magma chamber and at a later stage than orbicule formation tourmaline from massive quartz tourmaline rocks is concentrically zoned with major and trace element compositions indicating crystallization from a similar melt as for the orbicules but shows a more evolved signature

age dating and the orbital theory of the ice ages development of a high resolution 0 to 300 000 year chronostratigraphy using the concept of orbital tuning a continuous high resolution deep sea chronostratigraphy has been developed spanning the last 300 000 yr the chronology is developed using a stacked oxygen isotope stratigraphy and four different orbital tuning approaches each of which is based upon a different assumption concerning the response of the orbital signal recorded in the data each approach yields a separate chronology the error measured by the standard deviation about the average of these four results which represents the best chronology has an average magnitude of only 2500 yr this small value indicates that the chronology produced is insensitive to the specific orbital tuning technique used excellent convergence between chronologies developed using each of five different paleoclimatological indicators from a single core is also obtained the resultant chronology is also insensitive to the specific indicator used the error associated with each tuning approach is estimated independently and propagated through to the average result the resulting error estimate is independent of that associated with the degree of convergence and has an average magnitude of 3500 yr in excellent agreement with the 2500 yr estimate transfer of the final chronology to the stacked record leads to an estimated error of 1500 yr thus the final chronology has an average error of 5000 yr