estimating thermal inflow to el chichon crater lake using the energy budget chemical and isotope balance approaches abstract el chichon crater lake appeared immediately after the 1982 catastrophic eruption in a newly formed 1 km wide explosive crater during the first 2 years after the eruption the lake transformed from hot and ultra acidic caused by dissolution of magmatic gases to a warm and less acidic lake due to a rapid magmatic to hydrothermal transition input of hydrothermal fluids and oxidation of h 2 s to sulfate chemical composition of the lake water and other thermal fluids discharging in the crater stable isotope composition d and 18 o of lake water gas condensates and thermal waters collected in 1995 2006 were used for the mass balance calculations cl so 4 and isotopic composition of the thermal flux from the crater floor the calculated fluxes of thermal fluid by different mass balance approaches become of the same order of magnitude as those derived from the energy budget model if values of 1 9 and 2 mmol mol are taken for the catchment coefficient and the average h 2 s concentration in the hydrothermal vapors respectively the total heat power from the crater is estimated to be between 35 and 60 mw and the co 2 flux is not higher than 150 t day or 200 gm 2 day 1

isotope hydrology and geothermometry of the thermal springs damavand volcanic region iran abstract the chemo isotopic characteristics geothermal activity and water origin of the 5 thermal and 7 non thermal springs have been investigated in damavand volcanic region northern iran the damavand thermal waters are characterized by outlet temperature values of 23 to 65 c and the ca cl or ca so4 water types stable isotope values of 49 monthly precipitation samples from 5 stations at 2500 to 3200 m elevations were also measured in the study area and damavand meteoric water line dmwl was drawn as d 7 64 18o 8 93 r2 0 98 n 49 it has a lower slope and intercept than the global meteoric water line gmwl due to isotope kinetic fractionation effects during precipitation the 18o 0 0018 h m a s l 3 12 equation was derived based on precipitation data the reservoir temperature was estimated to be 110 135 c based on different geothermometers damavand volcano can be considered as the main heat source for the thermal springs in the region the conductive process along with the mixing of thermal waters with shallow cold groundwaters is the main cooling mechanisms almost all the thermal waters fall near the lmwl and within prediction interval area indicating meteoric origin and no significant effect of water rock interaction the damavand geothermal reservoir is fed by local meteoric water from altitudes of 2500 to 4100 m and circulates at least 500 m deep near the magma chamber

enhanced terrestrial weathering runoff and surface ocean carbonate production during the recovery stages of the paleocene eocene thermal maximum 1 the carbonate saturation profile of the oceans shoaled markedly during a transient global warming event known as the paleocene eocene thermal maximum petm circa 55 ma the rapid release of large quantities of carbon into the ocean atmosphere system is believed to have triggered this intense episode of dissolution along with a negative carbon isotope excursion cie the brevity 120 220 kyr of the petm reflects the rapid enhancement of negative feedback mechanisms within earth s exogenic carbon cycle that served the dual function of buffering ocean ph and reducing atmospheric greenhouse gas levels detailed study of the petm stratigraphy from ocean drilling program site 690 weddell sea reveals that the cie recovery period which postdates the cie onset by 80 kyr is represented by an expanded 2 5 m thick interval containing a unique planktic foraminiferal assemblage strongly diluted by coccolithophore carbonate collectively the micropaleontological and sedimentological changes preserved within the cie recovery interval reflect a transient state when ocean atmosphere chemistry fostered prolific coccolithophore blooms that suppressed the local lysocline to relatively deeper depths a prominent peak in the abundance of the clay mineral kaolinite is associated with the cie recovery interval indicating that continental weathering runoff intensified at this time as well robert and kennett 1994 such parallel stratigraphic changes are generally consonant with the hypothesis that enhanced continental weathering runoff and carbonate precipitation helped sequester carbon during the petm recovery period e g dickens et al 1997 zachos et al 2005

geochemistry of the thermal springs of mount taftan southeastern iran abstract thermal and cold water chemistry from the southern flank of mount taftan was investigated in order to discriminate among hydrochemical facies isotopic characteristics geothermal reservoir and identify the major geochemical processes that affect water composition the waters from both the hot and cold springs show high total dissolved solids content and are strongly to lightly acidic calcium is the dominant cation in terms of anions the taftan hot springs are cl so 4 type there is also a hco 3 type cold spring the so 4 cl ratios on an so 4 cl hco 3 diagram confirm the volcanic origin of the hot waters conservative elements indicate that the three types of analysed water have similar origin and the difference in concentration is due to dilution of thermal water with almost shallow fresh groundwater not affecting the elements proportions also the retrogressive 18 o enrichment with respect to the meteoric water line mwl confirms that thermal waters andesitic water have been diluted by shallow waters of meteoric origin comparison of the chemistry of thermal and cold springs and other evidences are indicative of an immature hydrothermal water system in taftan volcano because of waters immaturity temperatures in the geothermal reservoir in taftan region cannot be estimated accurately by applying na k k mg and quartz geothermometers

hydrochemical and isotopic δ18o δ2h 87sr 86sr δ37cl and δ81br evidence for the origin of saline formation water in a gas reservoir abstract the permo triassic kangan gasfield in southern iran is composed of an aquifer the kangan aquifer ka and an overlying gas reservoir it is located in the kangan and dalan formations and consists predominantly of limestone and dolomite the kangan gasfield is exploited from 36 wells at depths from 2300 to 2860 m the quality of the produced formation waters pfw varies from fresh to saline with salinities of up to 60 000 mg l the present study aims to identify the origin of the salinity of the pfws the concentration of major ions li sr and br as well as 18o d 87sr 86sr 37cl and 81br isotope compositions of the ka water and pfw samples a fresh and a brine spring and the persian gulf water were all measured the suite of isotopic 37cl and 81br and hydrochemical data li cl and br concentrations and cf index in this study indicates that the salinity origin of the pfws is evaporated seawater which could be either the ka water or the intergranular saturated brine in the kangan gas reservoir kgr both derived from permo triassic evaporated seawater 18o and 87sr 86sr data exclude the ka water as the source of the saline pfw leaving the intergranular brine of the kgr as the most likely source although further isotopic and geochemical tests are needed to verify this this work also proposes for the first time the use of a li cl versus br cl diagram to distinguish between evaporate formation water water modified by halite dissolution and fresh water it is recommended to apply these comprehensive methods to deep brine aquifers especially related to gasfields

geochemistry of thermal springs alhama de granada southern spain abstract the waters of the thermal springs at alhama de granada vary in temperature between 27 and 45 c temporal changes in the composition of the principal spring banos viejos indicate that a small degree of mixing may occur between deep thermal waters and shallow groundwater slight compositional variations also occur between the various thermal springs in the study area these spatial variations are due to the different local hydrodynamic conditions in the springs towards the north in less hydraulically transmissive rocks cooling of the rising water is more noticeable as are ion exchange and processes of so 4 reduction the chemical composition of the water is related to the dissolution of evaporites so 4 and cl salts carbonates and silicates and to the possible existence of sources of s within the rock estimates of the mean residence times have been obtained based on 14 c dic and t the state of thermodynamic equilibrium at the spring discharge was calculated using the solmineq 88 program the results indicate that all the samples are supersaturated with respect to quartz chalcedony cristobalite calcite aragonite and dolomite and undersaturated with respect to gypsum anhydrite and halite the use of different geothermometers and modelling of saturation indices for quartz albite and anhydrite indicate temperatures of about 110 c

recovering the true size of an eocene hyperthermal from the marine sedimentary record 1 hyperthermals episodes of abrupt global warming associated with the massive injection of carbon into the oceans and atmosphere represent possible analogs for future climate change however uncertainties in their magnitude rate and duration arising as a result of mixing processes and changes in carbonate preservation as the sediment record is formed complicate their use in constraining climate sensitivity and the role of carbon cycle feedbacks here we use cgenie an earth system model of intermediate complexity to assess likely magnitude and rate of carbon input taking a small hyperthermal event from the early middle eocene c22nh3 49 2ma as a case study we develop an iterative method combined with a sediment model simulating the formation and mixing of deep sea sediments to converge on an estimate for the true magnitude of the carbon cycle perturbation in the atmosphere and ocean that drives the event in inverting the 0 95 benthic 13 cexcursion recorded atocean drilling program site 1258 we obtain an estimate of at least 1 45 for the atmospheric co2 13 c excursion that drove event c22nh3 we also assess controls on intersite variation of event shape in model sediments and find that sedimentation rate is the strongest determinant of modeled event size with higher sedimentation rate sites recording the atmospheric signal more accurately our revised estimate for the size of c22nh3 implies a total carbon input almost two thirds higher than would be deduced if the recorded 13 c excursion magnitude was taken at face value

microstructural and geochemical perspectives on planktic foraminiferal preservation glassy versus frosty in recent years it has become apparent that the cool tropic paradox of paleogene and cretaceous greenhouse climates arises because of the diagenetic alteration of tropical planktic foraminiferal calcite near the seafloor yielding artificially high 18o values because the mg ca compositions of foraminiferal and inorganic calcite are thought to be quite different mg ca measurements should be a sensitive way of monitoring diagenetic alteration here we examine the extent of diagenetic alteration of eocene planktic foraminiferal calcite using scanning electron microscope imaging of foraminiferal test microstructures and geochemical 18o and mg ca analyses we compare microstructural and geochemical characteristics between given species exhibiting two contrasting states of preservation those that appear frosty under reflected light and those that appear glassy microstructural evidence reveals extensive diagenetic alteration of frosty foraminiferal tests at the micron scale while 18o analyses document consistently higher 18o and therefore lower paleotemperatures in this material yet we find that 18o offsets between species in these frosty foraminiferal assemblages appear to be generally preserved suggesting that frosty foraminifera remain valuable for generating relatively short approximately 1 myr paleoceanographic time series that do not demand absolute estimates of paleotemperature we also find that the observed increase in mg ca for planktic foraminifera exhibiting diagenetic alteration compared to glassy taphonomies is far smaller than would be expected from the addition of inorganic calcite based on laboratory derived mg2 partition coefficients our findings imply that a much lower mg2 partition coefficient controls inorganic calcite formation in deep sea sedimentary sections in accordance with the findings of baker et al 1982

rapid and sustained surface ocean acidification during the paleocene eocene thermal maximum the paleocene eocene thermal maximum petm has been associated with the release of several thousands of petagrams of carbon pg c as methane and or carbon dioxide into the ocean atmosphere system within 10 kyr on the basis of the co occurrence of a carbon isotope excursion cie widespread dissolution of deep sea carbonates and global warming in theory this rapid carbon release should have severely acidified the surface ocean though no geochemical evidence has yet been presented using boron based proxies for surface ocean carbonate chemistry we present the first observational evidence for a drop in the ph of surface and thermocline seawater during the petm planktic foraminifers from a drill site in the north pacific ocean drilling program site 1209 show a 0 8 decrease in boron isotopic composition 11b at the onset of the event along with a 30 40 reduction in shell b ca similar trends in 11b are present in two lower resolution records from the south atlantic and equatorial pacific these observations are consistent with significant global acidification of the surface ocean lasting at least 70 kyr and requiring sustained carbon release the anomalies in the b records are consistent with an initial surface ph drop of 0 3 units at the upper range of model based estimates of acidification

changes in benthic ecosystems and ocean circulation in the southeast atlantic across eocene thermal maximum 2 eocene thermal maximum 2 etm2 occurred 1 8 myr after the paleocene eocene thermal maximum petm and like the petm was characterized by a negative carbon isotope excursion and warming we combined benthic foraminiferal and sedimentological records for southeast atlantic sites 1263 1500 m paleodepth and 1262 3600 m paleodepth to show that benthic foraminiferal diversity and accumulation rates declined more precipitously and severely at the shallower site during peak etm2 as the sites are in close proximity differences in surface productivity cannot have caused this differential effect instead we infer that changes in ocean circulation across etm2 may have produced more pronounced warming at intermediate depths site 1263 the effects of warming include increased metabolic rates a decrease in effective food supply and increased deoxygenation thus potentially explaining the more severe benthic impacts at site 1263 in response bioturbation may have decreased more at site 1263 than at site 1262 differentially affecting bulk carbonate records we use a sediment enabled earth system model to test whether a reduction in bioturbation and or the likely reduced carbonate saturation of more poorly ventilated waters can explain the more extreme excursion in bulk 13c and sharper transition in wt caco3 at site 1263 we find that both enhanced acidification and reduced bioturbation during the etm2 peak are needed to account for the observed features our combined ecological and modeling analysis illustrates the potential role of ocean circulation changes in amplifying local environmental changes and driving temporary but drastic loss of benthic biodiversity and abundance

fault slip velocities inferred from the spectra of ground motions there is much practical need in obtaining independent information about earthquake source dynamic properties directly from observable data one such dynamic parameter the peak slip velocity during earthquake rupture can be calculated from the corner frequencies of the source spectra on the assumption of the validity of the 2 source model to obtain the source terms observed fourier spectra should be corrected for the site and path effects small to moderate earthquakes in japan recorded on multiple rock sites are well suited for the application of this methodology the results indicate that the maximum slip velocity of the selected earthquakes ranged from approximately 0 2 to 0 6 m sec direct observation based determinations of this type provide valuable physical information about the in situ faulting processes that can be used for constraining dynamics theories of faulting or in ground motion prediction

surviving rapid climate change in the deep sea during the paleogene hyperthermals predicting the impact of ongoing anthropogenic co2 emissions on calcifying marine organisms is complex owing to the synergy between direct changes acidification and indirect changes through climate change e g warming changes in ocean circulation and deoxygenation laboratory experiments particularly on longer lived organisms tend to be too short to reveal the potential of organisms to acclimatize adapt or evolve and usually do not incorporate multiple stressors we studied two examples of rapid carbon release in the geological record eocene thermal maximum 2 53 2 ma and the paleocene eocene thermal maximum petm 55 5 ma the best analogs over the last 65 ma for future ocean acidification related to high atmospheric co2 levels we use benthic foraminifers which suffered severe extinction during the petm as a model group using synchrotron radiation x ray tomographic microscopy we reconstruct the calcification response of survivor species and find contrary to expectations that calcification significantly increased during the petm in contrast there was no significant response to the smaller eocene thermal maximum 2 which was associated with a minor change in diversity only these observations suggest that there is a response threshold for extinction and calcification response while highlighting the utility of the geological record in helping constrain the sensitivity of biotic response to environmental change

hydrochemistry of geothermal water in tianshui and adjacent area gansu province china a geochemical study on thermal water has been carried out in tianshui and its adjacent area gansu province china chemical and isotopic contents were employed in the investigation on the origin and evolution of thermal water and the evaluation of reservoir temperature in the geothermal systems thermal waters in wushan and tianshui are characterized by outlet temperatures from 15 to 38 c and low tds 226 255 mg l defined as bicarbonate water its origin may be attributed to the interaction between meteoric rain biotite plagioclase gneiss and carbonate reservoir rocks in contrast thermal waters in tongwei and qingshui have higher outlet temperatures of 25 54 2 c and a moderate tds of 915 1 793 mg l regarded as sulfate waters these sulfate waters may arise from the interaction between meteoric water granite and amphogneiss isotopic data presented here suggest that thermal waters in the study area have a meteoric origin without being significantly effected by water rock isotope exchange chemical geothermometry indicates the existence of a deep geothermal reservoir of low to medium enthalpy 70 111 c in the tianshui study area

response of calcareous nannofossils to the paleocene eocene thermal maximum observations on composition preservation and calcification in sediments from odp site 1263 walvis ridge sw atlantic abstract in this study we present the results of a detailed analysis on calcareous nannofossil assemblages from sediment cores of odp site 1263 southern east atlantic walvis ridge this section represents one of the few complete deep sea sections that document the paleocene eocene thermal maximum petm in the pelagic realm the petm transient event was characterized by a brief but intense interval of global warming a global negative carbon isotope excursion cie and widespread dissolution of seafloor carbonate sediments paired analysis at polarizing light microscope lm and scanning electron microscope sem documents the different behavior of nannofossils through the different phases of the petm at the onset of cie within the cie and during the recovery interval the presence of anomalous specimens and morphotypes within some nannofossil taxa recorded during previous lm high resolution analyses has been further investigated in selected samples at the sem besides the known representatives of the cie petm excursion nanno flora as rhomboaster calcitrapa group and discoaster anartios the analysis revealed the presence of peculiar morphotypes of fasciculithus and deformed specimens of discoaster nobilis group discoaster mediosus and discoaster multiradiatus that are considered related to the anomalous amount of co2 in the ocean atmosphere system during the early phase of petm comparative analyses were performed in few selected samples from other petm sections located at different latitudes in the atlantic and pacific oceans although the anomalous geochemical conditions during the petm cie interval seem to have had some influence on the nannofossil production calcification and assemblage composition it results that local productivity together with post depositional diagenetic conditions were additional important controlling factors on nannofossil assemblages preliminary data from eocene thermal maximum 2 etm2 or elmo suggest that nannofossil malformations are not exclusive of the petm and are associated to other episodes of perturbation of the c cycle

origin of groundwater salinity in the fasa plain southern iran hydrogeochemical and isotopic approaches the study area the fasa plain is situated in the semiarid region of fars province in the south of iran the salloo diapir is a salt dome that crops out in the northwest of the study area isotopic and hydrochemical analyses were used to examine the water and how the origin of salinity and the diapir affect the quality of the groundwater quality in the study area groundwater was sampled from 31 representative pumping wells in alluvial aquifer and five springs in order to measure their stable isotope compositions bromide ion concentration and physical and chemical parameters the alluvial aquifer was organized into two main groups based on the chemistry with group 1 consisting of low salinity well samples 544 1744 s cm with water type ca mg hco3 so4 which were taken in the center and north of the area and group 2 consisting of high salinity samples 2550 4620 s cm with water type ca mg cl so4 which were taken from the wells in the south and southwest of the area a saline spring near the salt dome with an ec of 10 280 s cm has water type na cl while the compositions of the water in the other karstic springs is comparable to the fresh groundwater samples all groundwater samples are undersaturated with respect to gypsum anhydrite and halite and are supersaturated with respect to calcite and dolomite stable isotopes 18o and 2h differentiated four water types saline springs freshwater spring fresh groundwater and saline groundwater the results indicate that meteoric water is the main origin of these water resources halite dissolution from the salt dome was identified as the origin of salinity the na cl and cl br ratios confirmed the results groundwater compositions in the southwestern part of the area are affected by the intrusion of saltwater from the salt dome the average saltwater fraction in the some water wells is about 0 2 in the south and southwestern part of the area the saltwater fraction is positive in mixed freshwater saltwater group 2 different processes interact together to change the hydrochemical properties of fasa s alluvial aquifer the main processes that occur in the aquifer are mixing gypsum dissolution and calcite precipitation

early eocene warming events and the timing of terrestrial faunal exchange between india and asia the timing of initiation of continent continent collision between asia and india is controversial but this major tectonic event is generally thought to have occurred in the early eocene ca 50 ma new and independent data from strontium isotopes stable carbon isotopes microfossil biostratigraphy and mammal fossils from an early eocene marginal marine sequence cambay shale at the vastan lignite mine of western india indicate that terrestrial faunal exchanges and therefore continental collision between asia and the indian subcontinent took place before 53 7 ma this age coincides with the second eocene thermal maximum etm2 a short lived warming episode that followed the paleocene eocene thermal maximum petm ca 55 5 ma our data also document for the first time a clear record of the etm2 in terrestrial organic material from a low latitude site which is represented by a 3 4 carbon isotope excursion cie in lignite and dispersed organic carbon 13c values the magnitude of the cie at this location closely matches that observed in marine cores from the arctic ocean which supports an interpretation that this hyperthermal event though of lower magnitude was similar in character to that of the petm being a global phenomenon that affected both terrestrial and marine ecosystems

geothermal resources within carbonate reservoirs in western sicily italy a review abstract low to medium temperature fluid reservoirs hosted in carbonate rocks are some of the most promising and unknown geothermal systems western sicily is considered a key exploration area this paper illustrate a multidisciplinary and integrated review of the existing geological geochemical and geophysical data mainly acquired during oil and gas explorations since the 1950s specifically re analyzed for geothermal purposes has led to understanding the western sicily geothermal system as a whole and to reconstructing the modalities and particular features of the deep fluid circulation within the regional reservoir the data review suggests the presence of wide groundwater flow systems in the reservoir beneath impervious cap rocks we identified the main recharge areas reconstructed the temperature distribution at depth recognized zones of convective geothermal flow and depicted the main geothermal fluid flow paths within the reservoir we believe that our reconstruction of geothermal fluid circulation is an example of the general behavior of low to medium enthalpy geothermal systems hosted in carbonate units on a regional scale due to the recent technological developments of binary plants these systems have become more profitable not only for geothermal direct uses but also for power production

depth dependency of the paleocene eocene carbon isotope excursion paired benthic and terrestrial biomarker records ocean drilling program leg 208 walvis ridge 1 the paleocene eocene thermal maximum petm coincided with a negative carbon isotope excursion cie in carbonate and organic matter in terrestrial and marine records consequently the petm global warming of 5 6 c has been attributed to the rapid emission of a large amount of isotopically light carbon into the ocean atmosphere system and the magnitude of the cie has been used to estimate the amount of carbon greenhouse gas emitted however there are large discrepancies between the magnitude of the cie in marine and in terrestrial material in different types of marine carbonate records bulk carbonate planktic and benthic foraminiferal carbonate and in marine carbonate records from different locations the marine carbonate record of the cie may be incomplete in most deep sea bathyal abyssal locations because of ocean acidification and widespread dissolution of seafloor carbonates we demonstrate that the cie in benthic foraminiferal stable isotope records is relatively abrupt and not as gradual as portrayed in bulk carbonate records along the walvis ridge depth transect se atlantic the benthic cie is about 1 5 at 3600 m paleodepth in contrast to about 3 5 at 1500 m paleodepth consistent with depth dependent truncation by carbonate dissolution strong covariance between the benthic record and the stable carbon isotope values of terrestrial n alkanes isolated from the same core i e site 1263 supports a relatively rapid excursion of at least 3 5 but no more than 5 0

cenozoic exhumation history of the alborz mountains iran new constraints from low temperature chronometry the alborz mountains in the north of the turkish iranian plateau mainly developed in the cenozoic as a consequence of the closure of neo tethys and continental collision between arabia and eurasia cenozoic growth of the fold and thrust belt exploited an older palaezoic mesozoic crustal fabric but the extent to which this governed the overall form of the mountain belt is unclear to determine when and how the alborz mountain belt has grown apatite fission track aft and u th he ahe thermochronometry were performed on 46 bedrock samples collected along 8 transects across the range aft central ages range from 157 24 ma to 10 1 ma with most ages falling between 40 ma and 10 ma ahe ages range from 17 2 ma to 6 1 ma the data revealed enhanced exhumation ca 35 5 ma minor exhumation between ca 30 20 ma and an increase in exhumation thereafter this pattern matches the tripartite mid cenozoic stratigraphy of central iran where upper oligocene lower miocene carbonates are sandwiched between terrestrial clastic formations the most intriguing thermochronometric signal found is a major acceleration of exhumation that initiated in the late miocene to early pliocene recorded by the ahe data there does not appear to be a direct tectonic cause for pliocene intensified erosion as convergence rates between arabia and eurasia have remained relatively constant enhanced exhumation at this time may reflect a climatically induced intensification of erosion during caspian isolation and base level fall or a regional tectonic re organization of the arabia eurasia collision or both

modelling the oxygen isotope distribution of ancient seawater using a coupled ocean atmosphere gcm implications for reconstructing early eocene climate one of the motivations for studying warm climates of the past such as the early eocene is the enhanced understanding this brings of possible future greenhouse conditions traditionally climate information deduced from biological or chemical proxies have been used to test computer model simulations of past climatic conditions and hence establish some of the uncertainties associated with model based predictions however extracting climate information from proxies is itself an interpretative process and discrepancies between climate information inferred from different types of proxy undermines the assumption that model data conflicts automatically mean that the model is inherently flawed a new approach which both acknowledges and reduces the uncertainties associated with both model and data is required although the oxygen isotopic ratio 18o preserved in calcareous marine fossils has been used to reconstruct past seawater temperature for several decades significant uncertainties associated with this method persist these include assumptions about past seawater 18o for which no proxy exists and which is a key control on the temperature inferred from fossil carbonate here we present the results of an early eocene simulation made using a state of the art general circulation model gcm hadcm3 with co2 set at six times pre industrial values and which has oxygen isotopes incorporated into the full hydrological cycle and hence simulates the 18o of past seawater this allows us to explore the implications of the different seawater 18o correction factors commonly used for 18o based temperature reconstruction it also allows us to focus model data comparison on 18o rather than interpret ocean temperature an approach that reduces uncertainties in model data comparison since the effects of both the temperature and the isotopic composition of ocean water on 18o of carbonate are accounted for the good agreement between model and data for both modern and well preserved early eocene carbonate increases confidence in climate reconstructions of this time

hydrothermal systems of the karymsky volcanic centre kamchatka geochemistry time evolution and solute fluxes abstract karymsky volcanic centre kvc at the middle of the frontal volcanic chain of the kamchatka arc consists of two joined calderas akademii nauk and karymsky volcano and hosts two hydrothermal systems akademii nauk an and karymsky k the an is a typical boiling system with na cl waters tds 1 g l low gas content co2 n2 with deep calculated temperatures of 200 c in contrast springs of the k system have lower temperatures up to 42 c strong gas bubbling tds 2 5 g l and are enriched in hco3 and so42 with mg2 as the main cation there are two intriguing characteristics of the k field i their co2 rich gas 97 mol has the highest 3he 4he ratios ever measured for hydrothermal systems in kamchatka of 8 ra where ra 1 4 10 6 and ii their thermal waters have an unusual cation composition mg na ca after the 1996 sublimnic eruption within an caldera new hot springs appeared close to the eruption site in this paper we synthesize all published and new geochemical data sets the karymsky lake and post 1996 new thermal springs demonstrate exponential decreases in their main dissolved species with a characteristic time of 5 to 8 years the chemistry of an and k springs did not change after the eruption however the concentration of chloride in the lake water approached 35 mg l compared with a background of 8 11 mg l revealing a possible new source of hot water within the karymsky lake all thermal fields of the kvc are drained by the karymsky river with an outflow rate at the source of 2 m3 s flowing out from karymsky lake and at the exit from the karymsky caldera of 4 5 m3 s using the measured solute fluxes at the source an springs and at the exit an k springs the natural heat flux from the two systems can be estimated as 67 mw and 120 mw respectively and 20 t d for the chloride output from both systems

geothermometry applications for the balikesir thermal waters turkey in this study reservoir temperatures of balikesir geothermal waters in northwestern turkey are estimated with various geochemical models the geothermal fluids in the region are represented by na so4 na hco3 and ca hco3 type waters with discharge temperatures up to 98 c it was determined that the solubility of silica in most of the waters is controlled by the chalcedony phase equilibrium states of the balikesir thermal waters studied by means of na k mg ca diagram mineral saturation calculations and activity diagrams in the system composed of na2o cao k2o al2o3 sio2 h2o phases approximate a reservoir temperature of about 120 c most of the waters are found to be equilibrated with calcite chalcedony quartz and muscovite at predicted temperature ranges similar to those calculated from the chemical geothermometers

patterns and magnitude of deep sea carbonate dissolution during eocene thermal maximum 2 and h2 walvis ridge southeastern atlantic ocean 1 eocene thermal maximum 2 etm2 or h1 53 7 ma represents a short lived warming episode associated with the injection of a large mass of 13c depleted carbon into the ocean atmosphere system the mass of injected carbon the extent of deep sea dissolution and the amount of warming during etm2 appear to be approximately half of those documented for the paleocene eocene thermal maximum petm 55 5 ma but the pattern of lysocline migration during etm2 has not yet been documented sufficiently to decipher potential differences in carbon sources and sequestration mechanisms we present high resolution carbonate dissolution and bulk stable isotope records across etm2 and the successive h2 event 53 6 ma on a common age model for four sites along the walvis ridge depth transect 1500 to 3600 m paleowater depth to assess lysocline evolution the onset of etm2 is characterized by multiple depth dependent transitions of carbonate dissolution up to 96 of the total flux associated with rapid depletions in bulk carbonate carbon up to 1 1 5 and oxygen up to 0 7 1 5 isotope values h2 shows a 0 7 negative carbon isotope excursion with a coeval decrease in 18o of 0 5 and 80 of carbonate dissolution during etm2 the lysocline recovered within 30 ka we attribute this rapid recovery to terrestrial caco3 neutralization through enhanced chemical weathering of carbonates in soils and rocks according to theory carbonate dissolution was lower after recovery than prior to etm2 indicating carbonate ion oversaturation and a deeper position of the lysocline spectral analysis indicates that the changes in carbonate dissolution and 13c values were precession paced implying that weathering feedbacks and short term perturbations in the carbon cycle were important in determining early eocene background and hyperthermal ocean co32 conditions

time scale controversy accurate orbital calibration of the early paleogene 1 timing is crucial to understanding the causes and consequences of events in earth history the calibration of geological time relies heavily on the accuracy of radioisotopic and astronomical dating uncertainties in the computations of earth s orbital parameters and in radioisotopic dating have hampered the construction of a reliable astronomically calibrated time scale beyond 40 ma attempts to construct a robust astronomically tuned time scale for the early paleogene by integrating radioisotopic and astronomical dating are only partially consistent here using the new la2010 and la2011 orbital solutions we present the first accurate astronomically calibrated time scale for the early paleogene 47 65 ma uniquely based on astronomical tuning and thus independent of the radioisotopic determination of the fish canyon standard comparison with geological data confirms the stability of the new la2011 solution back to 54 ma subsequent anchoring of floating chronologies to the la2011 solution using the very long eccentricity nodes provides an absolute age of 55 530 0 05 ma for the onset of the paleocene eocene thermal maximum petm 54 850 0 05 ma for the early eocene ash 17 and 65 250 0 06 ma for the k pg boundary the new astrochronology presented here indicates that the intercalibration and synchronization of u pb and 40ar 39ar radioisotopic geochronology is much more challenging than previously thought

the geology of damavand volcano alborz mountains northern iran damavand volcano located in northern iran is a large 400 km 3 composite cone that is currently dormant it shows fumarolic activity near the summit but no evidence of eruption in the past 1000 yr the volcano represents an isolated focus of magmatism of uncertain tectonic affinity although geophysical and geochemical constraints point toward a local hotspot plume origin possibly associated with lithospheric delamination rather than any association with subduction new u th he and 40 ar 39 ar geochronological constraints indicate that the present cone young damavand has been constructed over 600 k y on an older eroded edifice of indistinguishable composition younger than 1 8 ma damavand activity has been characterized by the eruption of radially directed trachyandesite lava flows almost exclusively from summit vents limited pyroclastic activity has yielded thin fallout pumice lapilli layers and a few pyroclastic flows only one significant pyroclastic event is recognized in the remnants of a welded ignimbrite ponded and preserved along the haraz river drainage relatively short periods of volcanic eruptive activity were interspersed with longer periods of erosion in which volcanic products were transported particularly as hyperconcentrated flows into the surrounding drainage systems to be further reworked into epiclastic deposits occasional catastrophic events punctuated this interplay between volcanism and erosion at least one sector collapse is signified by the presence of a large debris avalanche deposit and the regional drainage systems appear to have been frequently dammed by incursions of volcanic material

an early eocene carbon cycle perturbation at 52 5 ma in the southern alps chronology and biotic response an early eocene carbon cycle perturbation at 52 5 ma from the southern alps chronology and biotic response