the serchio river catchment northern tuscany geochemistry of stream waters and sediments and isotopic composition of dissolved sulfate abstract the serchio river and its tributaries in northern tuscany were investigated for the chemical and isotopic compositions of waters and bed sediments bedrocks are mostly limestone dolomite and siliciclastics thermal spring systems are present in the catchment and the main industrial activity is represented by paper mills main results obtained are 1 major ions in solution appear to be basically controlled by precipitation and lithology as well as subordinately by direct inputs of thermal springs 2 human influence on metals in the waters along the main serchio and lima rivers is indicated at a number of sites by increases in concentration compared to the chemical composition of upstream tributaries 3 s and o isotope compositions delineate two main sources for aqueous so 4 2 that is dissolution of triassic evaporite directly or via thermal springs and oxidation of sulfide dispersed in siliciclastic rocks anthropogenic contributions are probable but they cannot be quantitatively assessed only so 4 2 in the notoriously polluted ozzeri tributary is suspected to be largely anthropogenic and 4 the chemical composition of bed sediments is mainly influenced by lithology apart from a number of technogenic elements in the upper part of the serchio river and in some tributaries contamination possibly occurs at other sites but geochemical indications are weak

channelized fluid flow through shear zones during fluid enhanced dynamic recrystallization northern apennines italy geochemical and petrographic studies of the triassic portoro limestone of the tuscan nappe in liguria italy indicate that fluid flow was channeled through interlayered bedding parallel shear zones during miocene shearing and low grade metamorphism carbon oxygen and strontium isotopic compositions and trace element concentrations in the portoro indicate that it was precipitated from normal marine waters in sheared and unsheared layers these isotopic compositions are indistinguishable yet sheared layers of microspar contain less than half the amount of strontium preserved in undeformed layers wavy grain boundaries and a dimensional preferred orientation of elongated grains indicate that calcite within sheared zones was dynamically recrystallized on the basis of these observations we suggest that during burial extraformational fluids were buffered into oxygen isotopic but not strontium concentration equilibrium with the portoro these syndeformational fluids were channeled through discrete 1 to 15 cm thick shear zones in which strontium was expelled from calcite and incorporated into grain boundary fluids during dynamic recrystallization

orbital scale stratigraphy and high resolution analysis of biogenic components and deep water oxygenation conditions in the japan sea during the last 640 kyr abstract paleoceanographic conditions in the japan sea changed drastically during the late quaternary in association with orbital and suborbital cycles and glacio eustatic sea level changes however few studies have examined long term sediment records older than 160 ka because of the lack of long and continuous cores and the difficulty in constructing high resolution age models in this study we first constructed an orbital scale stratigraphy of the sediments covering the last 640 kyr by comparing the specmap 18o curve and the 18o curve of planktonic foraminifera 18opf in the japan sea together with the combination zones of dominant planktonic foraminifera species then we reconstructed temporal variations in biogenic silica biosil and biogenic carbonate biocarb contents calculated from high resolution major element analysis data determined by an xrf microscanner in order to evaluate the deep water oxygenation conditions we also defined excess s as the difference between the content of s in the sediments and that for normal marine sediments calculated from the organic carbon content corg estimated from lightness l by assuming a total sulfur content stotal corg ratio of 0 36 and examined its variability biosil shows orbital scale variation and is generally low except during interglacial maxima when global sea level was high enough to allow a strong influx of the tsushima warm current biocarb shows orbital and suborbital scale variations and tends to be higher in dark layers deposited during glacial stages whereas the relationship is reversed during interglacial stages the low biocarb in dark layers deposited during interglacial stages is probably due to dissolution of biogenic carbonate caused by the increase in surface productivity as a result of the strong influx of nutrient rich east china sea coastal water and consequent increase in surface productivity and decomposition rate of organic matter in the intermediate water excess s tends to be higher in thicker dark layers deposited during glacial maxima when the sea level dropped below 90 m compared to adjacent light layers suggesting development of euxinic deep water conditions during these periods the results demonstrated the presence of orbital and suborbital scale variations in biosil and biocarb and their association with dark and light layers in the japan sea that reflect variations in the nature and strength of inflow through the tsushima strait controlled by both climatic and sea level changes whereas higher excess s reflects the development of euxinic deep water condition during glacial maxima in association with glacio eustatic sea level drops below 90 m during the last 640 kyr

origin of calcium sulfate type water in the triassic carbonate thermal water system in chongqing china a chemical and isotopic reconnaissance abstract chongqing located in the southwestern china was named as a spa city of the world it s most geothermal reservoirs are developed in carbonate rock aquifers and those thermal waters are characterized by high concentrations of sulfate and low hco3 however little was known about the origin and genesis of those thermal waters which is necessary for their protection and determination of regime of exploitation therefore thermal and surface waters were sampled seasonally and analyzed for hydrogeochemical and isotopic compositions 18o 2h 34s so4 18o so4 to decipher the origin of the thermal waters in the triassic carbonate aquifers in chongqing area key questions include the relative significance of hydrothermal processes and solute supply the results showed that 1 the major chemical composition of analyzed the thermal waters from chongqing area was characterized by ca so4 2 the 2h and 18o values of the thermal waters ranged from 48 6 to 63 1 with an average value of 54 2 and from 6 5 to 9 2 with an average value of 8 0 respectively indicating that the thermal waters originated from the local rain water with an elevation of 415 m to 1453 m above mean sea level 3 the estimated geothermal temperatures varied from 63 8 c to 78 3 c quartz indicating that the depth of the geothermal reservoir varied from 411 m to 1728 m which is located in the lower triassic jialingjiang formation 4 the 34s so42 and 18o so42 in the geothermal waters ranged from 29 7 to 34 1 with a mean value of 32 1 and from 12 5 to 16 5 with a mean value of 15 2 respectively suggesting that the high so42 concentrations resulted mainly from the dissolution of gypsum in the second part of the lower triassic jialingjiang formation 5 three processes of water rock interactions gypsum dissolution carbonate dissolution by carbonic acid and carbonate dissolution by sulfuric acid in the thermal system were unveiled by the hydrogeochemical and isotopic models among these three processes gypsum dissolution seems to be primarily responsible for solute composition of the thermal water this study also indicates the integration of hydrogeochemical and isotopic data is very useful tool to decipher the origin and genesis of the carbonate thermal waters

hydrogeochemistry and strontium isotopes in the arno river basin tuscany italy constraints on natural controls by statistical modeling summary in this paper the chemistry of major and trace elements and for the first time strontium isotopic ratios measured in running waters from the arno river basin tuscany central northern italy and thermal springs discharging in the same hydrographic system are presented and discussed classical graphical methods e g mixing diagrams have here been improved to identify in a correct statistical sample space extreme chemical compositions attributable to the action of geochemical processes and or inherited from specific lithologies namely contributions or components 1 2 and 3 to be used in inverse modeling procedures due to the absence of clear end members a linear least squares problem with non negativity constraints and distances as required for compositional data convex linear mixing was solved by considering the contribution of the most discriminant variables given by the 87 sr 86 sr isotopic ratios and the concentration of ca 2 mg 2 sr and rb following such approach it can be assumed p 2 mg 2 hco 3 radiogenic rich 87 sr 86 sr 0 71274 rb sr 0 039 represents a dominant feature at basin scale with a weight ranging from 69 to 100 much lower percentages are related to component 2 represented by a ca 2 mg 2 so 4 2 facies with intermediate 87 sr 86 sr 0 70874 and low rb sr 2 8 10 4 ratios and component 3 identified by ca 2 hco 3 facies with less radiogenic 87 sr 86 sr 0 70827 and low mg 2 ca 2 0 011 ratios these components are mainly dominated by the dissolution of evaporitic rocks and or mixing with thermal waters in the southern part of the arno river basin and by dissolution of the carbonatic fraction kinetically favored with respect to that of the silicatic minerals in the upper reaches of the main course and its tributaries respectively

seawater intrusion in the guanahacabibes peninsula pinar del rio province western cuba effects on karst development and water isotope composition the water resources in the guanahacabibes peninsula are distributed in two areas the northeastern area is characterized by swamps wetlands and lagoons with a low contribution of seawater whereas the area in the southwestern plain shows a considerable development of the karst structures that limits the existence of superficial waters but permits the ingression of the surrounding seawater in this latter area the groundwater showed a marked increase in salinity with the depth in particular groundwater with a seawater fraction of 0 1 had the lowest ca mg carbonates saturation indexes calculated by modeling the mixing between freshwater and seawater using different software thermodynamic databases and equations for activity coefficients generally seawater and groundwaters with an added seawater fraction above 0 60 0 65 showed similar oversaturated indexes in high mg calcites and pure ca carbonates calcite and aragonite differently in the groundwater that showed carbonates undersaturation generally with a seawater fraction between 0 02 and 0 60 the saturation indexes in high mg calcites were 0 2 lower than pure ca carbonates locally the bacterial reduction of the dissolved sulfate enhanced the dissolution of the limestone contributing to the increased development of the karst structures and the seawater intrusion finally the presence near the coastline of fresh ca and na bicarbonate waters was in accordance with the upward flow of the shallow freshwater during the formation of the saline wedge however the oxygen and hydrogen stable isotope composition of the waters showed a probable contribution to the area from a deep aquifer that is recharged in the highest reliefs of the province cordillera de guaniguanico

timing of post depositional events in the burano formation of the secchia valley upper triassic northern apennines clues from gypsum anhydrite transitions and carbonate metasomatism the burano evaporite formation from the secchia river valley is an up to 2200 m thick sequence composed of meter to decameter scale interbeds of gypsum anhydrite and dolostones with minor halite the deposit has been affected by a complex array of post depositional modifications thermal events and large scale evaporite dissolution preventing a satisfactory reconstruction of the environment of deposition the modifications are intense because these rocks were the main decollement horizon during the formation of the northern apennines chain the carbonate rocks are massive and or laminated dolomitic mudstone wackestone oolitic packstones and oolitic peloidal bioclastic grainstones which commonly appear as mega boudins within a sulfate groundmass the dolostones to 3 7 to 3 0 pdb have been affected by mg metasomatic replacement by magnesite to 2 6 to 1 4 pdb induced by hydrothermal circulation total homogenization temperatures of fluid inclusions in hydrothermal magnesite range from 275 to 310 c the anhydrite rocks are characterized by flow structures such as centimeter scale pseudo lamination composed of aligned prismatic crystals with transposed isoclinal folds outlined by dolostones fragments homogenization temperatures of fluid inclusions in authigenic quartz incorporated into sulfate rocks range from 260 to 305 c emilia and from 230 to 315 c tuscany the gypsum rocks are composed of xenotopic irregular cloudy crystals and more rarely by centimeter scale idiotopic crystals showing the same structures as the anhydrite rocks the origin of the gypsum rocks is due to late alteration of anhydrite by migration of sharp hydration fronts the hydration is a two step process and is revealed by the presence in the gypsum rocks of corroded anhydrite micro relics and authigenic quartz crystals which include anhydrite the role of the burano evaporites during the apennines tectogenesis can be depicted as follows a prevalent deposition of gypsum in the upper triassic b gypsum dehydration at burial conditions to form anhydrite cretaceous c syn tectonic flow of anhydrite rocks brecciation of dolostones syn tectonic growth stage of quartz euhedra at deep burial conditions possibly related to the development of the oligocene miocene greenschist facies apuane metamorphic complex d hydrothermal deposition of sparry magnesite and partial mg metasomatic replacement of dolostones by magnesite e sub surface dissolution of halite to form thick matrix supported residual caprock like anhydrite mega breccias f complete gypsification of anhydrite at sub surface conditions and g evaporite dissolution at surface exposure producing dolostone breccias with partial calcitization and removal of most clasts calcare cavernoso

the bagni di lucca thermal waters tuscany italy an example of ca so4 waters with high na cl and low ca so4 ratios abstract the bagni di lucca thermal waters lucca province tuscany italy have been well known since the middle age for their alleged curative properties in the present work the waters have been analysed for major and trace components and for o h s and sr isotopes the 2 h and 18 o values indicate a meteoric origin of the waters and the tritium content suggests long term more than 40 years circulation at depth the 34 s values in dissolved sulphate of the warmest waters doccione paolina bernabo demidoff cova indicate interaction with triassic evaporites however the 34 s values as well as the 87 sr 86 sr ratios in the waters appear to be a little higher on average 17 6 0 4 and 0 70834 0 00006 respectively than in triassic sulphate minerals from the northern apennines 16 0 0 5 and 0 70778 0 00011 the waters are ca sulphate and characterised by high na cl 2 and low ca so 4 0 7 mole ratios high sr 12 mg l f 4 2 mg l as 80 g l cs 70 g l rb 107 g l and salinity up to 3087 mg l of total dissolved solids low alkalinity and ph in the range 6 3 7 5 assuming equilibrium of the waters with anhydrite and chalcedony the evaluated temperature and pressure are about 70 75 c and 200 300 bar considering the pressure as hydrostatic the evaluated depth of equilibration approaches that of the metamorphic basement about 3 0 3 8 km underlying the carbonate evaporite formations occurring in the area thermodynamic computations indicate that the high na cl ratio and the low ca so 4 ratio in the waters may be due to progressive dissolution of albite anhydrite dolomite and carbon dioxide accompanied by calcite precipitation the linear correlations between the major and trace components including 2 h and 18 o demonstrate that thermal springs undergo dilution by low salinity shallow waters which are recharged at low elevation

hydroquakes central apennines italy towards a hydrogeochemical monitoring network for seismic precursors and the hydro seismo sensitivity of boron abstract hydrogeochemical changes before mw 5 0 earthquakes are hoped to be applicable as seismic precursors it is now necessary to pass from single experiences to structured networks systematically monitoring large seismic areas for long periods our aim is to provide a pilot methodological experience for how such networks could be realized and the types of results they could deliver we present the method and some initial results to document the method s applicability in 2017 we started the hydroquakes project in seismically active central italy with the sulmona and matese areas selected as the two monitoring nodes each node includes 5 6 monitored springs and for each spring we performed laboratory analyses of major and trace elements and some isotopes we installed in situ probes for continuous monitoring between december 2017 and january 2020 the most energetic earthquakes were three events with mw of 3 9 4 1 and 4 4 they were not preceded by significant hydrogeochemical anomalies except for the mw 4 1 event despite its low mw this earthquake occurred over a large normal fault at a great depth in the crust 17 km and was preceded by weak but detectable hydrogeochemical anomalies of boron and 11b that were similar but milder than the hydrogeochemical anomalies before the 2016 mw 6 0 earthquake in the central apennines this and previous evidence show the b and 11b hydro seismo sensitivity and indicates that pre seismic hydrogeochemical anomalies could arise mostly before mw 5 0 earthquakes with weak exceptions occurring in specific conditions such as long and deep faults

hydrochemical and statistical studies of the groundwater salinization in mediterranean arid zones case of the jerba coastal aquifer in southeast tunisia coastal aquifers are considered as major sources for freshwater supply worldwide especially in arid zones the weak rainfall as well as the intensive extraction of groundwater from coastal aquifers reduce freshwater budget and create local water aquifer depression causing both seawater intrusion and a threat to groundwater this phenomenon was observed in the jerba island which is located in southeast tunisia jerba s unconfined aquifer shows high values of groundwater salinity reaching locally 17 g l and a strong contrast between some zones of the aquifer high pumping rates and weak recharge disturb the natural equilibrium between fresh and saline water causing water salinization in most areas of the island this study aims at establishing the salinity map of the aquifer and identifying the origin of groundwater salinization the salinity map shows that zones characterized by low groundwater salinity are located in the center of the study area high groundwater salinities are observed near the coast and in some parts having low topographic and piezometric levels groundwater geochemical characterization and br cl and na cl ratios suggest that the origin of abnormal salinity is seawater intrusion considering groundwater salinity values and br concentrations a seawater intrusion map is established it shows that many areas of the unconfined aquifer are contaminated by mixed groundwater and seawater the statistical analysis demonstrates that high mineralization of the groundwater is due to gypsum and carbonate dissolution coupled with the mixed groundwater and seawater in many areas

depositional mechanics of the 1902 pyroclastic nueeardente deposits of mt pelee martinique abstract pyroclastic flows are believed to have a rheology similar to other gravity mass flows such as turbidity currents avalanches or debris flows gravity plays a major role in controlling the mobility of a nuee ardente the paroxismal nuees being differentiated by their larger mass by the initial direction of the trajectory produced by the explosion and by their higher velocity the 1902 deposits of mt pelee accumulated from primary flows the deposits may be grouped into two different facies 1 a coarse grained thick bedded agglomerate that has characteristics similar to debris flow deposits and 2 a well stratified lapilli tephra and ash that has characteristics of turbidity current deposits these deposits result from two different types of flow generally laminar for the agglomerate and turbulent for the lapilli tephra and ash the maximum grain size used previously as an indicator of flow competence is valid for the traction load of the turbulent suspension but is unrealistically high for a true suspension load the coarsest size in the turbulent flow deposits probably did not travel in true suspension and a value of 5 on the cumulative distribution is more realistic for the evaluation of the shear velocity needed for true suspension although representing a maximum size application of the reynolds number criteria to the may 8 and 20 1902 nuees that destroyed st pierre indicates that turbulence is their only possible physical state in agreement with the observed characteristics of the deposits mean flow velocity of pure air necessary to support the 5 size in true suspension 140 984 m s 1 is unrealistically high however increasing the density at the base of the turbulent flow to 0 01 or 0 05 g cm 3 decreases the settling velocity of the grains significantly and brings the mean flow velocity needed to support all grains except the largest down to the observed values of the 1902 eruptions the larger grains require a higher mean flow velocity and or a higher density increasing flow density provides a reasonable answer to the suspension problem of the coarse fraction in turbulent nuees ardentes

sulfur and oxygen isotopes in italian marine sulfates of permian and triassic ages evaporitic sulfates of permian and triassic ages from italian occurrences were analyzed for sulfur and oxygen isotopes in order to supplement the corresponding isotope age curves and to use isotopic data to trace the origin of the sulfate in hydrologic systems the sulfur isotopic composition age relationships obtained in this study generally agree with those found throughout the world in two cases i e in samples from the carniola di bovegno formation bergamo and brescia alps and from the lower part of the gracilis formation recoaro vicenza sulfur isotopes suggest different ages for the rocks than the formerly ascribed ones oxygen isotopic compositions show the same range from 10 5 to 18 5 without any consistent relationship with sulfur these ranges of values are almost identical to those published previously for sulfates of permian and triassic ages from other locations

a hydrodynamic classification of grain shapes abstract the relationship between the fall velocity and orthogonal axis ratios of differently shaped grains with stable settling patterns is examined contrary to what is generally supposed the ratio of the intermediate to the long diameter di dl which is related to the maximum projection area normal to the direction of settling appears to have the least influence the best correlation is shown by the ratio of the short to the long diameter ds dl with ds di giving less accurate results a modified hydrodynamic shape index given by 1 ds dl x is proposed which yields an improved simplified settling equation applicable to spheroids prolate and oblate spheroids discs cylinders and ellipsoids there appears to be a unique value of x for different grain shapes settling within specific ranges of reynolds numbers based on the results of this study a hydrodynamic classification of grain shapes is proposed

high resolution rapid elemental analysis using an xrf microscanner abstract the horiba energy dispersive xrf microscanner is an instrument designed for nondestructive high resolution rapid semiquantitative chemical mapping under ordinary atmospheric conditions however its application to quantitative analysis has not yet been attempted in this study we developed a nondestructive rapid high resolution quantitative analytical method for fine grained rocks using this instrument average concentrations and elemental mapping images of a small square region 0 5 mm 0 5 mm to 100 mm 100 mm can be obtained for major elements mg al si k ca ti mn fe within 100 seconds per measurement high resolution continuous measurements of slabbed fine grained sedimentary rock samples are easily achieved a stratigraphic interval of 1 m can be measured with 1 cm resolution within 10 hours which is several times faster than the conventional x ray fluorescence method

an evaporite based high resolution sulfur isotope record of late permian and triassic seawater sulfate abstract variations in the sulfur isotope composition of dissolved marine sulfate through time reflect changes in the global sulfur cycle and are intimately related to changes in the carbon and oxygen cycles a large shift in the sulfur isotope composition of sulfate at the permian triassic boundary has been recognized for long time and a number of studies were carried out to understand the causes and significance of this shift however data for the middle and late triassic are very sparse and the stratigraphic evolution of the sulfur isotope composition of seawater is poorly constrained due to the small number of samples analyzed and or due to the limited stratigraphic intervals studied moreover in the last few years the triassic timescale has significantly changed due to a wealth of new radiometric and stratigraphic data in this study we show that for the late permian and the triassic it is possible to obtain a precise reconstruction of the evolution of the sulfur cycle for parts of it at sub million year resolution by analyzing exclusively gypsum and anhydrite deposits we base our reconstruction on new data from the middle and late triassic evaporites of northern switzerland and literature data from evaporites from germany austria italy and the middle east we propose a revised correlation between the well dated marine tethyan sections in northern italy and the evaporites from northern switzerland and from the germanic basin calibrated to the newest radiometric absolute age scale this new correlation allows for a precise dating of the evaporites and constructing a composite sulfur isotope evolution of seawater sulfate from the latest permian lopingian epoch to the norian we show that a rapid positive shift of approximately 24 at the permian triassic boundary can be used to constrain seawater sulfate concentrations in the range of 2 6 mm thus higher than previous estimates but with less rapid changes finally we discuss two possible evolution scenarios for the middle triassic negative shift to values of 15 that subsequently remain constant during the late triassic

o h and sr isotope evidences of mixing processes in two geothermal fluid reservoirs at yangbajing tibet china the yangbajing geothermal field with the highest reservoir temperature among chinese hydrothermal systems is located about 90 km northwest to lhasa city capital of tibet where high temperature geothermal fluids occur in two reservoirs a shallow one at a depth of 180 280 m and a deep one at 950 1 850 m in this study oxygen 18 and deuterium isotope compositions as well as 87sr 86sr ratios of water samples collected from geothermal wells cold springs and surface water bodies were characterized to understand the genesis of geothermal fluids at yangbajing the results show that the deep geothermal fluid is the mixing product of both magmatic and infiltrating snow melt water whereas the shallow geothermal fluid is formed by the mixing of deep geothermal fluid with cold groundwater using a binary mixing model with deep geothermal fluid and cold groundwater as two endmembers the mixing ratios of the latter in most shallow geothermal water samples were calculated to be between 40 and 50 the combined use of o h and sr isotopes proves to be an effective approach to depict the major sources of geothermal fluids and the mixing processes occurring in two reservoirs at yangbajing

structure and late cenozoic evolution of the upper lithosphere in southwest tuscany italy abstract geological and geophysical data on southwest tuscany are reviewed in order to define the structure and evolution of the upper lithosphere from the miocene to the quaternary petrologic studies reveal the existence below all of tuscany of hercynian and older polyphased metamorphic rocks and of hercynian granite whose top is an important seismic reflecting horizon the basement is characterized by ne sw trending structures in contrast with the main nw se alpine structures of the uppermost levels the heat flow map shows two broad areas with values higher than 80 mw m2 reaching maximum values of 10 5 and 15 h f u in the geothermal areas which are also characterized by negative bouguer anomalies a landsat study revealed a ne sw band of subcircular structures passing through larderello and coinciding with a regional fault system and a steep rise in the moho petrologic geochemical and radiometric data on the tuscan igneous rocks show that partial melting took place in the tuscan crust at different levels and to varying degrees from the miocene to quaternary producing a continuous alpine granitic layer the known tuscan intrusive bodies and two batholiths below the larderello and mt amiata geothermal fields represent culminations of the alpine granite the rise of the tuscan magmas was closely correlated to a post tortonian tensional tectonics and followed its n e migration tensional tectonics started after the last compressional phase 10 11 ma b p as a consequence of the anticlockwise rotation of italy the opening of the tyrrhenian sea and the swelling of the mantle below southwest tuscany

statistical analysis of textural data from complex pyroclastic sequences implications for fragmentation processes of the agnano monte spina tephra 4 1 ka phlegraean fields southern italy the agnano monte spina eruption 4 1 ka generated pyroclastic deposits with complex internal stratigraphy that reflects variations in eruptive style to obtain constraints on the fragmentation processes we analysed grain size and scanning electron microscopy sem data by means of multivariate statistical techniques of the cluster and factor analysis types the results allow the identification of end member deposits related to either pure magmatic activity or pure phreatomagmatic activity in addition some deposits show evidence of the contemporaneous operation of both end member fragmentation modes the presence of the two contrasting fragmentation processes during the various phases of explosive activity is tentatively interpreted to be a function in inhomogeneities in gas exsolution processes within the magma column that feeds the eruption

the fractal and multifractal dimension of volcanic ash particles contour a test study on the utility and volcanological relevance abstract image processing analysis is used to check the ability of the fractal dimension for quantitatively describing the shape of volcanic ash particles digitized scanning electron microscopy images of fine pyroclasts from the eruptions of monte pilato rocche rosse lipari italy are investigated to test the efficiency of the fractal dimension to discriminate between particles of different eruptive processes multivariate analysis of multiple fractal components allows distinction between magmatic particles and phreatomagmatic particles which however is less significant than the discrimination obtained in previous studies by the use of simple adimensional shape parameters approximation of the actual particle boundary and the not rotation invariant nature of the fractal data frequently result in a significant scatter of data points in the mandelbrot richardson plot such behavior obscures in some cases the actual information of particle shape and renders the discriminating power of fractal analysis less effective than classical shape descriptors data less affected by scatter reveal that phreatomagmatic particles of the monte pilato rocche rosse eruptions are true mono fractals whereas magmatic particles are multifractals the textural small scale fractal of magmatic particles is similar to the fractal dimension value of phreatomagmatic particles and is attributed to the rheological behavior of melt upon brittle fragmentation the structural large scale fractal of magmatic particles refers to the walls of ruptured vesicles that lay on the particle outline the high difference between the values of the textural and structural fractals of magmatic particles of the monte pilato rocche rosse eruptions suggests two distinct and independent processes in the formation of such pyroclasts at the scales corresponding to the textural fractal the fragmentation process is independent of vesicles magmatic fragmentation is not simply related to growth expansion interference and explosion of vesicles but to a brittle cracking of the highly viscous melt likely related to rapid decompression

correlating specific conductivity with total hardness in gypsum karst waters modern digital conductivity meters are readily portable robust cheap and give precisely reproducible values of specific electrical conductivity spc in s cm 1 here we investigate the accuracy of their estimates of the amounts of gypsum dissolved in waters collected in gypsum karst terrains expressed as total hardness th in mg l 1 of caso4 2h2o gyp total dissolved solid concentrations tds are also considered curves obtained with the program phreeqc for the dissolution of pure gypsum in water at 25 c are compared with 574 comprehensive water chemical analyses selected from gypsum karst studies in europe and the americas principal common and foreign ions encountered are the bnc group bicarbonates nitrates chlorides it is found that gyp 1 12 spc 62 where bnc 2400 s cm 1 gyp 0 74 spc 777 where bnc 3100 s cm 1 gyp 0 97 spc 209 where bnc 4300 s cm 1 there are similar results for the more complex waters found in gypsum karsts where much carbonate rock or salt is also present to the limit of bnc 0 8 copyright 2006 john wiley sons ltd

origin of rhythmical bedding in middle miocene siliceous rocks of the onnagawa formation northern japan abstract centimeter to decimeter scale rhythmical alternation of dark and light layers is common in siliceous rocks of the middle miocene onnagawa formation of northern japan the siliceous rocks may also show micrometer scale laminae considered to be varves dark layer frequency shows meter scale cyclic variation with dominant spectral peaks of approximately 10 5 4 3 4 2 3 and 1 6 m for these a varve tuned average sedimentation rate of 139 m yr yields periods of 72 39 24 17 and 12 kyr respectively a sedimentation rate of 100 m yr which is within the range of biostratigraphically calculated rates yields 100 54 34 23 and 16 kyr respectively considering the uncertainty in the estimation of the average sedimentation rate these values are in relatively good agre ment with orbital eccentricity obliquity and precessional cycles respectively bottom water oxygenation levels deduced from the lamina preservation index are in phase with the frequency variation of dark layers suggesting that it is also controlled by orbital cycles mineral and chemical analyses suggest that the siliceous rocks are mainly composed of biogenic diagenetic silica terrigenous detritus dolomite and organic matter with minor amounts of carbonate fluorapatite the dark colors are due to detritus and organic matter thus alternation of dark and light layers and variation in the frequency of dark layers reflect compositional variation mass accumulation rates mars of biogenic silica and terrigenous detritus are calculated from the average thickness of a lamina couplet dry bulk density and chemical composition of individual samples at the level of centimeter to decimeter layers mar of detritus is nearly constant whereas mar of biogenic silica varies by a factor of 2 on the other hand mar of detritus shows meter scale variation with amplitudes as high as a factor of 10 which is in phase with frequency cycles of dark layers whereas mar of biogenic silica does not show significant meter scale variation compositional variation represented by dark and light alternation and frequency cycles of the dark layers are a result of the interplay of centimeter to decimeter scale 102 3 years variation in mar of biogenic silica and meter scale 104 years variation in mar of detritus the latter could be related to global sea level oscillation caused by orbital cycles

influence of the water content on x ray fluorescence core scanning measurements in soft marine sediments the x ray fluorescence xrf core scanner provides bulk sediment chemistry data measured nondestructively at the split core sediment surface although this method is widely accepted there is little known about the effects of physical properties such as density and water content on xrf core scanner data comparison of xrf scanner measurements from the sediment surface and dry powder samples of sediment core geob7920 indicates strongly reduced element intensities for the lighter elements al and si we relate the lower element intensities of the measurements taken at the sediment surface to the amount of water in the sample volume analyzed by the xrf core scanner the heavier elements k ca ti and fe remain relatively unaffected by the variation of any physical property within sediment core geob7920 additionally we successfully use the elemental intensity of cl as a proxy for the seawater content in the sample volume analyzed by the xrf core scanner this enables the establishment of a correction function for the elements al and si that corrects for the radiation absorption of the water content in sediment core geob7920 off cape blanc nw africa

application of scanning x ray analytical microscope to the petrographic characterization of a ductile shear zone an alternative method to image microstructures abstract a ductile shear zone within a metasomatic biotite band in the ryoke granite teshima sw japan has been studied using the scanning x ray analytical microscope sxam this enabled the quantitative distributions of major elements such as si k fe al and ca to be determined within the shear zone these element maps were processed to transform them into images showing the distribution of minerals such as quartz biotite plagioclase and k feldspar which form the major minerals within the biotite band and the granite protolith mineral profiles based on these mineral maps compared with the simple shear strain profile reveal that the shear zone is most intense where quartz and biotite have been substituted for the primary mineral assemblage of the granite protolith suggesting that the stresses imposed on the granite caused the shear strain to localize along the biotite band to produce the observed shear zone it appears that the rheological behavior changed around 50 60 of quartz modal composition

hydrogeochemistry of high temperature geothermal systems in china a review as an important part of the mediterranean himalayas geothermal belt southern tibet and western yunnan are the regions of china where high temperature hydrothermal systems are intensively distributed of which rehai yangbajing and yangyi have been investigated systematically during the past several decades although much work has been undertaken at rehai yangbajing and yangyi to study the regional geology hydrogeology geothermal geology and geophysics the emphasis of this review is on hydrogeochemical studies carried out in these geothermal fields understanding the geochemistry of geothermal fluids and their environmental impact is critical for sustainable exploitation of high temperature hydrothermal resources in china for comparison the hydrogeochemistry of several similar high temperature hydrothermal systems in other parts of the world are also included in this review it has been confirmed by studies on cl and stable isotope geochemistry that magma degassing makes an important contribution to the geothermal fluids from rehai yangbajing and yangyi though meteoric water is still the major source of recharge for these hydrothermal systems however the mechanisms of magma heat sources appear to be quite different in the three systems as recorded by the 3he 4he ratios of escaping geothermal gases a mantle derived magma intrusion to shallow crust is present below rehai although the intruding magma has been heavily hybridized by crustal material by contrast the heat sources below yangbajing and yangyi are inferred to be remelted continental crust besides original sources the geochemistry of characteristic constituents in the geothermal fluids have also been affected by temperature dependent fluid rock interactions boiling and redox condition changes occurring in the upper part of hydrothermal systems and mixing with cold near surface waters the geothermal fluids from rehai yangbajing and yangyi contain very high concentrations of some toxic elements since local drinking water sources may be mixed with geothermal water and irrigation with water containing geothermally derived harmful elements possibly leading to accumulation in crops consumed by human beings the natural geothermal spring discharge or anthropogenic geothermal wastewater drainage of these fields poses a threat to the environment and human health future research work should focus on estimation of stable o and h isotope compositions of magmatic water related to high temperature hydrothermal systems in china which is of significance for the quantitative source study of geothermal fluid recharged by degassed magmatic waters attention should also be paid to some constituent species in geothermal fluid of strong environmental significance such as thioarsenate that is crucial for the fate of as discharged from geothermal springs especially sulfidic hot springs

shape entropy and settling velocity of natural grains abstract the shape of sedimentary particles has been quantified by many different form indices which have been utilized mainly in determining grain hydrodynamic behavior although the orthogonal axis dimensions required for calculating shape indices are easily measured in the case of grains larger than 2 mm this is impractical for sand and silt different data sets of the settling velocity of natural quartz grains varying in size between 0 0001 and 1 cm are used in this paper to determine their mean hofmann shape factor which defines a polynomial curve in the grain size range from clay to medium size pebbles sand exhibits the highest sphericity culminating with coarse to very coarse sand the two polynomial equations describing the curve are employed to determine the settling velocity of natural grains with a mean accuracy of 95 1 4 5 the latter is similar to that obtained for both smooth ellipsoids and angular grains which suggests that grain roundness does not play a major role in the settling velocity of particles up to a reynolds number of at least 4 200

comments on turbulent boundary layer shear flows as an approximation of base surges at campi flegrei southern italy by dellino et al 2004 dellino et al 2004 use some principles of sediment mechanics to estimate the flow behaviour of base surge deposits at astroni and agnano monte spina in southern italy to do so they assume quasisteady incompressible shear flow for the basal part of the surges hypothesizing that at the transition between a basal inversely graded bed and an overlying finely laminated bed the shields criterion and suspension criterion are simultaneously valid they combine the two criteria to get

geochemical modeling of the madison aquifer in parts of montana wyoming and south dakota stable isotope data for dissolved carbonate sulfate and sulfide are combined with water compo sition data to construct geochemical reaction models along eight flow paths in the madison aquifer in parts of wyoming montana and south dakota the sulfur isotope data are treated as an isotope dilution problem whereas the carbon isotope data are treated as rayleigh distillations all reaction models reproduce the observed chemical and carbon and sulfur isotopic composition of the final waters and are partially validated by predicting the observed carbon and sulfur isotopic compositions of dolomite and anhydrite from the madison limestone the geochemical reaction models indicate that the dominant groundwater reaction in the madison aquifer is dedolomitization calcite precipita tion and dolomite dissolution driven by anhydrite dissolution sulfate reduction ca mg2 ina cation exchange and halite dissolution are locally important particularly in central montana the groundwater system is treated as closed to c02 gas from external sources such as the soil zone or cross formational leakage but open to c02 from oxidation of organic matter coupled with sulfate reduction and other redox processes occurring within the aquifer the computed mineral mass transfers and modeled sulfur isotopic composition of madison anhydrites are mapped throughout the study area carbon 14 groundwater ages adjusted for the modeled carbon mass transfer range from modem to about 23 000 years b p and indicate flow velocities of 7 7 ftlyr 2 1 26 5 rnlyr most horizontal hydraulic conductivities calculated from darcy s law using the average 14 c flow velocities are within a factor of 5 of those based on digital simulation the calculated mineral mass transfer and adjusted 14 c groundwater ages permit determination of apparent rates of reaction in the aquifer the apparent rate of organic matter oxidation is typically 0 12 jlidol uyr sulfate and to a lesser extent ferric iron are the predominant electron acceptors the kinetic biochemical fractionation of 34 s between sulfate and hydrogen sulfide is approximately 44 o at 25 c with a temperature variation of

cortex a shipboard xrf scanner for element analyses in split sediment cores abstract the cortex corescanner texel is a non destructive xrf system for the logging of split sediment cores it is a seaworthy instrument that remains active during heavy weather conditions the scanner produces reliable counts for k to sr highly correlated with concentrations measured with atomic absorption spectrometry aas the option to scan al si and elements heavier than sr is in preparation a core section of 1 m can be scanned at 2 cm intervals within an hour a maximum resolution of 1 mm can be achieved at present each region and sedimentary environment requires separate calibration in the nearby future the generator settings will be standardized which may result in the development of a standard calibration procedure because of the high resolution of its semi quantitative records the cortex is a useful tool for detailed time series analysis inter core correlation and shipboard analysis

turbulent boundary layer shear flows as an approximation of base surges at campi flegrei southern italy abstract small volume base surge deposits of astroni and agnano monte spina eruptions at campi flegrei consist of sets of beds formed by the passage of multiple pyroclastic density currents each set is made by a fining upward sequence consisting from base to top of 1 an inversely graded layer made of bombs and lapilli 2 a finely laminated layer with wavy bedforms made of coarse ash and fine lapilli 3 a structureless fine ash bed lack of discontinuities at layer contacts allows us to hypothesize that each set of beds represents the passage of one pyroclastic density current the sequence formed as a function of the decreasing particle transportation capability of the base surge during the waxing sustained waning phases of flowage we make the simplifying assumptions that the flow on passing from the deposition of the inversely graded layer to the deposition of the finely laminated layer had low particle concentration was quasi steady and incompressible by such assumptions some of the equations that regulate sediment mechanics are applicable to the base surges of campi flegrei to reconstruct flow density and shear velocity in between the deposition of the two layers structural and textural features of deposits stress the importance of shear and turbulence during transportation and suggest that the turbulent boundary layer shear flow is a good approximation to such pyroclastic density currents we used the coles formula to reconstruct velocity as a function of flow height during the formation of the finely laminated layer of astroni and agnano monte spina base surges the methodology we used allows the reconstruction of flow parameters just at a particular point in time and space of base surge evolution and does not provide the complete picture of the flow history of pyroclastic density currents nevertheless flow velocity and density data as obtained with the proposed approach point to dynamic pressure values that are compatible with those reported for similar currents on other volcanoes we conclude therefore that the results obtained give approximate but helpful information on the nature of such hazardous events at campi flegrei

rb sr and k ar ages on minerals at temperatures of 300 400 c from deep wells in the larderello geothermal field italy rb sr and k ar ages have been obtained on six biotites two muscovites and one hornblende from samples of micaschist gneiss and amphibolite of lower paleozoic to precambrian age at a depth exceeding 2 000 m in basement rocks of the larderello travale geothermal region most of the data cluster in the range 2 5 3 7 ma revealing the existence of a pliocene thermal event to which the origin of the field may be attributed the resulting duration of the larderello geothermal field is unexpectedly long in the basement levels of the two wells examined unstabilized minimum temperatures of 290 and 380 c were measured all the biotites show almost complete 40ar and 87sr retention at the measured well temperatures petrologic evidence stilpnomelane stability and experimental data activation energies and diffusion coefficients also favour a closure temperature above 400 c for rb sr and k ar in biotites in agreement with recent direct experimental determinations

the suitability of the pieve fosciana hydrothermal system italy as a detection site for geochemical seismic precursors abstract the serchio valley is one of the regions of highest seismic risk in tuscany italy as a part of a seismic prevention prediction pilot project funded by regional government of tuscany the geochemical and hydrologic processes that control the composition of the thermal waters emerging near the pieve fosciana village pra di lama site have been investigated to assess the suitability of the site for the monitoring of geochemical precursors of earthquakes the investigation protocol considered the coupled use of chemical analyses on water aliquots sampled during discrete surveys and of continuous signals for selected physical chemical parameters acquired via an automatic station equipped with a suite of parameter specific sensors concentrations of major inorganic dissolved aqueous components have been processed with geochemical modeling techniques to obtain a quantitative description of water rock interactions occurring at depth in local mesozoic aquifers the geochemical background of the system was defined by combining these data and an integrated hydrogeological and geochemical model of the hydrothermal aquifer feeding the springs was elaborated based on the very low variability of physical and geochemical parameters over a long observation time the relatively long and deep underground circulation paths of discharged waters under confined conditions the site specific sensitivity of monitored parameters to local crustal strain and the proximity to seismically active neotectonic structures the pieve fosciana system ranks as a favorable site for recognizing fluids possibly connected to energy release and or permeability variations induced by seismogenic processes at depth the integrated geological hydrogeological geochemical and modeling approach presented here could be profitably applied for the design of similar projects elsewhere

dating thrust events using 87 sr 86 sr an example from the northern apennines italy isotopic and petrographic analyses of the major thrust zone calcare cavernoso in the apuane region of the northern apennines are used to date the timing of motion on that thrust zone and to document the type and the amount of fluid focused there the thrust zone consists of a porous cataclasite composed of polylithologic clasts and finely crystalline dolomite included within a recrystallized calcite matrix that shows no affect of subsequent brittle or ductile deformation 87 sr 86 sr isotopic compositions of clasts and matrix from around the entire apuane region 1000 km 2 are very uniform with values that average 0 70811 the strontium data suggest recrystallization of the entire thrust zone by huge volumes of focused fluid flow that caused complete and uniform resetting of the original triassic sr isotopic signature by oligocene sea water during oligocene thrusting preservation of fragile vein networks that also yield the oligocene sea water sr ratios suggests that significant post th

circulation path of thermal waters within the laga foredeep basin inferred from chemical and isotopic δ18o δd 3h 87sr 86sr data abstract the geochemistry of thermal spring waters in the acquasanta terme area located on the adriatic side of central italy has been investigated in order to characterize the geothermal feeding system the springs discharge more than 100 l s at temperature ranging between 20 and 30 c they occur in a tectonic window of mesozoic limestones in the central sector of the acquasanta anticline within the laga foredeep basin chemical and isotopic compositions of thermal and cold fluids were investigated most of them monitored for one year in order to understand the thermal fluid circulation paths the chemistry of the major elements defines the existence of na cl and ca cl so42 hot discharging waters and permits the characterization of the thermal end member hosted in carbonate dominated reservoir burano anhydrites fm calcare massiccio fm this deep fluid is well represented by the sample t1 and shows high temperature and electrical conductivity ec very stable over time and not affected by mixing phenomena this is also confirmed by tritium results 0 t u close to the surface at different depth such water undergoes mixing or dilution processes with hco3 rich freshwaters driven by the complex structural setting of the area and by diffuse karst caves this is identified as the main reason for observed compositional variations of sampled springs and three areas affected by different mixing phenomena have been defined at the surface the concentrations of so42 and h2s suggest redox processes affecting sulfur after interaction with evaporitic formations identified with the burano anhydrites at the base of the umbria marche sedimentary sequence 3500 m deep contribution from this reservoir is also supported by characteristic sr isotope signature 18o and d values indicate a meteoric origin of the thermal waters and allow estimation of an average infiltration altitude ranging between 1500 and 1700 m a s l this datum supported by structural data suggests the laga mountains as the recharge area of the system reservoir temperature inferred by so42 hco3 f ca mg and so42 f geothermometers is about 80 c consistent with the geothermal gradient of the foredeep basin and deserving further investigations for potential economic implications about this low enthalpy geothermal area

isotopic composition of precipitation in italy a first overall map abstract composite monthly samples of atmospheric precipitation were collected over different periods of time ranging from one to seven years at 77 different locations throughout italy these samples were measured for their oxygen and hydrogen isotopic composition to obtain basic information for hydrological and meteorological studies in this area on the basis of the results obtained a first map of the isotopic composition of precipitations in italy has been drawn up the main features of this map are the following 1 no isotopic latitudinal gradient has been found along the tyrrhenian coast from sicily to the italian french border despite the considerable range of latitude 2 a minor latitudinal gradient is found in the southeasternmost section of the country apulia partially favored by the local morphology 3 a marked shadow effect of the apennines is apparent along the southern section of the po valley and along the central section of the adriatic coast 4 the contribution of water vapor from the northernmost section of the adriatic sea affects the eastern and central sections of the po plain 5 the shadow effect of the alps is considerably smaller than expected 6 the isotopic vertical gradients calculated in nine different areas and based on groups of two to five different stations vary but are essentially close to about 0 2 100 m 7 when mean monthly temperature values were available their relationship with the isotopic composition of precipitation was found to be on average very poor 8 the relationship between mean 18o and mean d calculated for the collection locations shows shifts of both the slope and the deuterium excess when compared to the global meteoric water line these shifts are different for northern central and southern italy 9 in a few cases anomalously low monthly values suggest the existence of pronounced amount effects

a combined geochemical and isotopic study of the fluids discharged from the montecatini thermal system nw tuscany italy abstract the thermo mineral fluids discharges of montecatini terme northern apennines tuscany italy have been exploited since the roman times and despite the fact that this thermal complex is one of the biggest in europe the most recent geochemical investigations were published almost 40 years ago to fill this gap in this paper a detailed geochemical and isotopic investigation on the main thermal springs and wells from the montecatini thermal system mts is presented the chemical and isotopic features of the montecatini waters suggested that they are mainly controlled by water rock interaction processes between meteoric water permeating at depth from the surrounding reliefs up to 800 m a s l and the triassic evaporites burano formation belonging to the tuscan sedimentary series the local stratigraphic and tectonic framework favors an efficient recharge of the hydrothermal reservoir by the meteoric precipitation from a large catchment area and this aspect plays a fundamental role for the longevity of the montecatini thermal spas notwithstanding the huge amount of thermal water exploited the 3h values indicated that the thermal waters are likely related to a relatively long 50 years fluid circulation pattern approaching the surface thermal and saline waters mix with cold and low tds total dissolved solids waters hosted in short shallow aquifer s whose chemistry is dictated by the interaction of rain waters with silico clastic rocks of low solubility geothermometric estimations in the f so42 hco3 system suggested the occurrence of a main fluid reservoir at t 80 95 c and pco2 0 5 bars such co2 pressure is consistent with values estimated for other thermal springs from central southern tuscany being co2 basically supplied by a deep source nevertheless 13c co2 and 13c tdic values were lower than those expected for a mantle thermometamorphic co2 source this can be explained by i isotopic fractionation occurring during calcite precipitation and or ii mixing with biogenically derived gases occurring at relatively shallow depth

the chemistry and isotopic composition of waters in the low enthalpy geothermal system of cimino vico volcanic district italy abstract geothermal energy exploration is based in part on interpretation of the chemistry temperature and discharge rate of thermal springs here we present the major element chemistry and the d 18o 87sr 86sr and 11b isotopic ratio of groundwater from the low enthalpy geothermal system near the city of viterbo in the cimino vico volcanic district of west central italy the geothermal system hosts many thermal springs and gas vents but the resource is still unexploited water chemistry is controlled by mixing between low salinity hco3 rich fresh waters