total co2 output from vulcano island aeolian islands italy 1 total co2 output from fumaroles soil gas bubbling gas discharges and water dissolved gases discharged from the island was estimated for vulcano island italy the co2 emission from fumaroles from the la fossa summit crater was estimated from the so2 crater output while co2 discharged through diffuse soil emission was quantified on the basis of 730 measurements of co2 fluxes from the soil of the island performed by using the accumulation chamber method the results indicate an overall output of 500 t day 1 of co2 from the island the main contribution to the total co2 output comes from the summit area of the la fossa cone 453 t day 1 with 362 t day 1 from crater fumaroles and 91 t day 1 from crater soil degassing the release of co2 from peripheral areas is 20 t day 1 by soil degassing palizzi and istmo areas mainly an amount comparable to both the contribution of water dissolved co2 6 t day 1 as well as to seawater bubbling co2 4 t day 1 measured in the istmo area presented data september 2007 refer to a period of moderate solphataric activity when the fumaroles temperature were 450 c and gas water molar ratio of fumaroles was up to 0 16 the calculated total co2emission allows the estimation of the mass release and related thermal energy from the volcanic hydrothermal system

volatile fluxes through the big bend section of the san andreas fault california helium and carbon dioxide systematics abstract to investigate the source of volatiles and their relationship to the san andreas fault system safs 18 groundwater samples were collected from wells near the big bend section of the safs in southern california and analyzed for helium and carbon abundance and isotopes concentrations of 4 he corrected for air bubble entrainment vary from 4 15 to 62 7 10 8 cm 3 stp g 1 h 2 o 3 he 4 he ratios vary from 0 09 to 3 52 r a where r a air 3 he 4 he consistent with up to 44 mantle helium in samples a subset of 10 samples was analyzed for the major volatile phase co 2 the hypothesized carrier phase of the helium in the mantle crust system co 2 3 he ratios vary from 0 614 to 142 10 11 and 13 c co 2 values vary from 21 5 to 11 9 vs pdb 3 he 4 he ratios and co 2 concentrations are highest in the wells located in the mil potrero and cuddy valleys adjacent to the safs the elevated 3 he 4 he ratios are interpreted to be a consequence of a mantle volatile flux though the safs diluted by radiogenic he produced in the crust samples with the highest 3 he 4 he ratios also had the lowest co 2 3 he ratios the combined helium isotope he co 2 elemental relationships and 13 c co 2 values of the groundwater volatiles reveal a mixture of mantle and deep crustal metamorphic fluid origins the flux of fluids into the seismogenic zone at high hydrostatic pressure may cause fault rupture and transfer volatiles into the shallow crust we calculate an upward fluid flow rate of 147 mm a 1 along the safs up to 37 times higher than previous estimates kennedy et al 1997 however using newly identified characteristics of the safs we calculate a total flux of 3 he along the safs of 7 4 10 3 cm 3 stp a 1 0 33 mol 3 he a 1 and a co 2 flux of 1 5 10 13 cm 3 stp a 1 6 6 10 8 mol a 1 1 of previous estimates lower fluxes along the big bend section of the safs suggest that the flux of mantle volatiles alone is insufficient to cause the super hydrostatic pressure in the seismogenic zone however results identify crustal metamorphic fluids as a major component of the co 2 volatile budget which may represent the additional flux necessary for fault weakening pressure in the safs

chemical and isotopic compositions of thermal springs fumaroles and bubbling gases at tacana volcano mexico guatemala implications for volcanic surveillance this study presents baseline data for future geochemical monitoring of the active tacana volcano hydrothermal system mexico guatemala seven groups of thermal springs related to a nw se oriented fault scarp cutting the summit area 4 100m a s l discharge at the northwest foot of the volcano 1 500 2 000m a s l another one on the southern ends of tacana la calera the near neutral ph from 5 8 to 6 9 thermal t from 25 7 c to 63 0 c hco3 so4 waters are thought to have formed by the absorption of a h2s so2 co2 enriched steam into a cl rich geothermal aquifer afterwards mixed by na hco3 enriched meteoric waters originating from the higher elevations of the volcano as stated by the isotopic composition d and 18o of meteoric and spring waters boiling temperature fumaroles 89 c at 3 600m a s l nw of the summit formed after the may 1986 phreatic explosion emit isotopically light vapour d and 18o as low as 128 and 19 9 respectively resulting from steam separation from the summit aquifer fumarolic as well as bubbling gases at five springs are co2 dominated the 13cco2 for all gases show typical magmatic values of 3 6 1 3 vs v pdb the large range in 3he 4he ratios for bubbling dissolved and fumarolic gases from 1 3 to 6 9 atmospheric 3he 4he ratio r a is ascribed to a different degree of near surface boiling processes inside a heterogeneous aquifer at the contact between the volcanic edifice and the crystalline basement 4he source tacana volcano offers a unique opportunity to give insight into shallow hydrothermal and deep magmatic processes affecting the co2 3he ratio of gases bubbling springs with lower gas water ratios show higher 3he 4he ratios and consequently lower co2 3he ratios e g zarco spring typical central american co2 3he and 3he 4he ratios are found for the fumarolic agua caliente and zarco gases 3 1 1 6 1010 and 6 0 0 9 r a respectively the l s 5 9 0 5 and l s m ratios 9 2 0 7 for the same gases are almost identical to the ones calculated for gases in el salvador suggesting an enhanced slab contribution as far as the northern extreme of the central american volcanic arc tacana

helium isotopes in dead sea transform waters abstract the concentrations and isotopic compositions of helium and relative abundances of co2 were studied in brines and freshwater springs groundwater wells and gas bubbles in and around the dead sea transform dst fault system the latter forms part of the plate boundary between the african and arabian plates along which intensive tectonic and volcanic activity occurred and where a range of freshwater to hypersaline water bodies percolate the atmosphere normalized 3he 4he ratios r ra show a distinct geographic gradient whereby fluids in the north part of the dst near lake kinneret are characterized by r ra 2 these values decrease gradually southward until the arava valley where they are approximately 0 15 reflecting a corresponding decrease in the mantle derived he fraction from about 30 in the north to a few percent in the south freshwater springs outside the dst in the galilee and judea mountains are characterized by r ra ratios close to unity reflecting the dominance of atmosphere derived helium although they still contain a few percent of a mantle component the spatial pattern of change in r ra ratios is independent of regional tectonic activity rifting which is similar around the lake kinneret basin and the dead sea and a correlation does not exist between such activity and he concentrations and co2 3he ratios in contrast helium concentrations and to a lesser extent co2 he ratios correlate with temperatures of the sampled fluids reflecting a dilution process of a deep hot mantle component as it percolates upwards toward the surface the preferential injection of a mantle he toward the surface in the north dst is facilitated by deep faults and a shallower moho boundary which are also associated with enhanced volcanism in the north dst and is superimposed over a regionally scaled mantle background value regionally the observations reflect a transition from a domination of a dilute mantle end member in the north which itself is the product of a mixture between mantle and crustal helium to a dominant crustal radiogenic end member in the south the r ra ratio in basaltic olivines and diopside from the golan is on average 6 6 0 7 lower than typical mantle values 8 but corresponding to comparable sub continental mantle compositions

chemical assembly of archean anorthosites from amphibolite and granulite facies terranes sw greenland we report whole rock major and trace element compositions obtained by xrf and ina methods for the amphibolite facies buksefjorden and granulite facies nordland anorthosites sw greenland in a previous petrologic study on the same sample suite we documented differences in texture mineralogy and mineral compositions between these two anorthosite bodies chemical analyses confirm differences in composition between the two bodies but these differences cannot be explained by variations in metamorphic conditions and point towards differences in the nature of their protoliths analyzed nordland samples are anorthosites and leucogabbros with 88 98 normative plagioclase whereas those from buksefjorden include anorthosite leucogabbro and gabbro with 55 95 normative plagioclase two or more compositional groupings can be recognized at each site which correspond to differences in color and mineralogy of the hand samples samples from buksefjorden are mainly quartz normative whereas those from nordland are olivine nepheline normative other differences include higher ni co ratio and ree contents in the granulite facies anorthosites from nordland ree pattern shapes are similar however being moderately fractionated at 0 5 10 chondrites with positive eu anomalies calculated equilibrium melt patterns are similar for both anorthosites being relatively flat at 50 150 chondrites suggesting unfractionated but evolved parental magmas olivine must have been present in the protoliths of the nordland rocks compared with buksefjorden otherwise the protoliths contained plagioclase with variable an content an62 an92 and a mafic component with variable fe mg mg 0 3 0 8 this mafic component was either hornblende or a combination of ortho and clinopyroxene in fixed proportions plus a small amount of magnetite mixing calculations demonstrate that some buksefjorden anorthosites contain two varieties of plagioclase a calcic type that may correspond to cumulus crystals and a sodic type that may correspond to a trapped melt component on plots of normative whole rock an versus mg compositions of the buksefjorden and nordland anorthosites form crude negative arrays that differ from the generally positive trends of mafic layered intrusions kiglapait skaergaard and from the generally flats trends of plagioclase rich cumulate rocks st urbain and stillwater anorthosites this difference provides further evidence for the distinctive nature of archean calcic anorthosite complexes compared with other types of mafic intrusions moreover this distribution of data points is consistent with the assembly of the protolith of the sw greenland anorthosites mainly as mixtures of plagioclase and hornblende finally the field for the buksefjorden and nordland anorthosites overlaps only slightly with that for the fiskenaesset complex thus extending the known range of compositions for archean anorthosites in west greenland

chemical features and isotopic composition of gaseous manifestations on vulcano island aeolian islands italy an interpretative model of fluid circulation abstract between 1987 and 1995 gases were sampled from various manifestations on vulcano island including various fumaroles at la fossa crater and baia di levante and diffuse soil gas emissions in several areas which are characterized by high c02 fluxes since the end of 1987 volcanic activity has increased considerably showing a marked rise in temperature 300 c in 1987 to 670 c in december 1992 and in output of steam from crater fumaroles in addition variations have been observed in the chemical and isotopic compositions of gases and thermal waters which can be attributed to an increased inflow of deeper fluids the isotopic composition of fumarolec steam seems to be the result of mixing processes between a positive endmember of deep origin d 10 15 18o 6 8 and two endmembers of meteoric origin with different oxygen shifts variations observed in the c02 isotopic composition suggest that all sampled manifestations are fed by a single deep source which may be magmatic such a source would be characterized by the 613cco2 values of high temperature fumaroles 13cco2 0 these values are noticeably more positive than those generally attributed to magmatic gases 13cco2 5 8 implying crustal contamination processes of the magma the observed decrease in 18oco2 values of the crater fumaroles from 20 in 1978 to between 12 and 15 in 1993 1994 was probably caused by two different processes the first is a reduction of the enrichment factor between c02 and h2o which is related to the increased temperature of the gases and the second is a mixing with more negative waters of meteoric origin finally c02 addition or removal processes caused by interactions between deep gases and shallow hydrothermal waters are likely to be responsible for the different chemical and isotopic compositions of gaseous emissions in the vulcano porto area and the crater fumaroles

a geochemical traverse along the sperchios basin e evoikos gulf graben central greece origin and evolution of the emitted fluids the studied area is a 130 km long fast spreading graben in central greece its complex geodynamical setting includes both the presence of a subduction slab at depth responsible for the recent quaternary volcanic activity in the area and the western termination of a tectonic lineament of regional importance the north anatolian fault a high geothermal gradient is made evident by the presence of many thermal springs with temperatures from 19 to 82 c that discharge along the normal faults bordering the graben in the period 2004 2012 58 gas and 69 water samples were collected and their chemical and isotopic analysis revealed a wide range of compositions two main groups of thermal waters can be distinguished on the basis of their chemical composition the first represented by dilute waters e c 0 6 ms cm of the westernmost sites is characterised by the presence of ch4 rich and mixed n2 ch4 gases the second displays higher salinities e c from 12 to 56 ms cm due to mixing with a modified marine component reservoir temperatures of 150 160 c were estimated with cationic geothermometers at the easternmost sites along the graben from west to east the gas composition changes from ch4 to co2 dominated through mixed n2 ch4 and n2 co2 compositions while at the same time the he isotopic composition goes from typical crustal values 0 1 r ra up to 0 87 r ra showing in the easternmost sites a small 3 11 but significant mantle input the 13c values of the co2 rich samples suggest a mixed origin mantle and marine carbonates

volatiles and energy released by purace volcano total co2 output of purace volcano colombia was estimated on the basis of fluids discharged by fumaroles soil gases and dissolved carbon species in the aquifer the soil co2 emission was computed from a field survey of 512 points of co2 soil flux measurements at the main degassing areas of purace volcano the co2 flux from purace s plume was estimated using an indirect method that used the so2 plume flux and co2 so2 ratio of the main high temperature fumarole the total output of co2 was estimated at 1500 t day the main contribution of co2 comes from the plume summit degassing and from soil degassing that emit 673 and 812 t day respectively the contributions of summit and soil degassing areas are comparable indicating an intermediate degassing style partitioned between closed and open conduit systems the estimated water vapor discharge as derived from the chemical composition of the fumaroles the h2o co2 ratio and the so2 plume flux allowed calculation of the total thermal energy fumarolic soil degassing and aquifer released from the purace volcanic system this was 360 mw

palaeomagnetic evidence for early pleistocene in the central and northern north sea the palaeomagnetic evidence presented here refutes the earlier hypothesis that most of the quaternary succession in the central north sea area is of middle to upper weichselian age a study of the quaternary seismic stratigraphy has been tied to 11 cored boreholes which are being examined for their physical properties and faunal content initial palaeomagnetic studies show a major reversely magnetized zone which can be correlated from borehole to borehole and with the seismic stratigraphy this reversely magnetized zone is thought to represent the matuyama epoch which ended 790 000 yr bp consequently this suggests the presence of early pleistocene strata in the central and northern north sea

soil and fumarole gases of mount etna geochemistry and relations with volcanic activity abstract between 1993 and 1996 gas samples were collected on mt etna volcano from both high and low temperature fumaroles and from soils in areas of anomalous degassing located on the flanks of the volcanic edifice the chemical composition of all the emitted gases is consistent with their magmatic origin during their transport to the surface they would undergo shallow mixing processes mostly with air locally as in the case of a point in the lower southwestern flank of the volcano p39 very high contents of he and ch4 indicate that deep gases mainly interact with ground waters and also with a hydrocarbon reservoir the isotopic composition of carbon in co2 from these gases also suggests its primary magmatic origin with inferred 13 c values of magmatic co2 in the range 2 to 1 vs pdb such values significantly more positive than those measured in morbs are in the typical range measured at the other mediterranean volcanoes 5 to 0 more negative values can be explained by shallow interactions between magmatic and organic co2 and or between the former and cold t 120 c ground waters both chemical and isotopic gas geothermometers agree in indicating calculated temperatures ranging from 180 to 270 c for the soil gases collected from low temperature fumaroles near the summit and temperatures around 150 c for the cold gases from p39 thus confirming the presence of a hydrothermal aquifer beneath this point a chemical geothermometer applied on the gases collected from the high temperature fumaroles near the summit craters shows equilibrium temperatures ranging from 385 to 690 c lastly many of the studied parameters showed anomalous variations in time during the studied period the most important of these concerned the flux of co2 through the soil and the concentration of soil h2 which were closely correlated with strong increases in the volcanic activity of etna

the evolution of marine evaporitic brines in inland basins the jordan dead sea rift valley marine evaporitic brines frequently display na cl and br concentrations that significantly deviate from seawater evaporation paths yielding markedly conflicting degrees of evaporation calculated for a specific brine here we present 493 new and 33 previously reported analyses of ca chloridic waters of neogene age from the dead sea rift dsr valley to explain such offsets the dsr brines plot along an almost perfect mixing line r2 0 990 on a br cl na cl diagram extending between two end members a and b points a and b are located at na cl 0 804 and br cl 0 00193 and at na cl 0 00773 and br cl 0 0155 respectively within the halite and bischofite stability fields brines a and b originated in a dual mode evaporation basin brine a formed under the classic lagoon scenario mode a with seawater inflow and brine outflow at steady state occasional drops in water level imposed by climatic or tectonic causes resulted in outflow cutoff and in rapid concentration buildup the second mode b initiated upon equilibration of the activity of water in the brine with the overlying relative humidity resulting in composition and salinity approaching that of brine b sustaining it until the next reversal to mode a thick evaporite deposits inhibited infiltration of brines a and b into the subsurface terrain a process that was enabled only when the brine reached the permeable carbonate rock rim and border faults of the basin hence brines that formed during the relatively short shifts from mode a to mode b could not penetrate into the deep subsurface and bittern minerals that were formed during the frequent mode shifts were dissolved and flushed out into the sea upon the next resumption of outflow the proposed model accounts for the deviations of brines from the marine evaporitic evolution curve by brine mixing rather than due to a change in ocean chemistry it also explains the absence of bittern minerals in the thick halite and gypsum anhydrite succession and the compositional gap between the widely different end member hypersaline fluids this model applies directly to the studied dsr brines and evaporites but it may be relevant to other inland evaporitic basins

a juvenile oceanic island arc origin for the archean ca 2 97 ga fiskenaesset anorthosite complex southwestern greenland evidence from oxygen isotopes abstract the archean ca 2 97 ga fiskenaesset layered intrusion southwestern greenland consists of an association of anorthosite leucogabbro gabbro hornblendite pyroxenite peridotite and dunite the intrusion is characterized by well preserved igneous layering cumulate texture and primary igneous minerals including olivine pyroxene plagioclase hornblende and chromite we use new whole rock n 36 and mineral n 32 oxygen isotopic data for all major lithologic units from the best preserved stratigraphic section of the fiskenaesset complex at majorqap q va to revisit geodynamic and petrogenetic hypotheses proposed for the origin of archean terranes the fiskenaesset complex has modern mantle like whole rock o isotope compositions o 18 5 8 0 5 average o 18 values increase from peridotite o 18 5 0 through hornblendite o 18 5 7 gabbro o 18 5 8 pyroxene hornblendite o 18 6 0 and leucogabbro o 18 6 3 to anorthosite o 18 6 3 these whole rock isotopic compositions reflect the approximate modal abundances of olivine average o 18 4 9 hornblende average o 18 5 7 clinopyroxene average o 18 6 4 and plagioclase average o 18 6 4 in each rock type as a consequence of mineral fractionation in the magma chamber s field relationships and the absence of crustal contamination suggest that the fiskenaesset complex formed in an oceanic setting subduction zone like whole rock trace element signatures and mantle like o 18 and initial e nd values are consistent with formation of these rocks in a juvenile oceanic island arc setting field and geochemical data from the fiskenaesset region and adjacent terranes suggest that the origin of archean crust in southwestern greenland is consistent with phanerozoic like plate tectonic processes rather than density driven sinking delamination and diapiric processes requiring formation of greenstone belts and anorthosite complexes on pre existing continental crust mantle like o 18 values in the ca 2 97 ga fiskenaesset complex are inconsistent with substantial recycling of continental crust indicating that the fiskenaesset rocks originated distal from continental sources

chemical evolution of saline waters in the jordan dead sea transform and in adjoining areas the ca mg relationship in groundwaters strongly points to the overall dolomitization and local albitization the mg ca ratios reveal two trends by which saline waters develop increase of mg ca ratio by evaporation and decreasing mg ca ratios due to dolomitization and albitization br cl vs na cl ratios demonstrate that albitization does not play a major role which leaves dolomitization to be the main source for decreasing mg ca ratios in saline waters in the eastern and southern region of lake kinneret salinization occurs by mixing with a ca mg molar ratio 1 dominates which developed by the albitization of plagioclase in abundant mafic volcanics and the dolomitization of limestones the most saline groundwater of the tabgha fuliya and tiberias clusters could be regional derivatives of at least two mother brines in diluted form one is represented by ha on water the other is a na rich brine of the zemah type additionally a deep seated ca dominant brine may ascend along the fractures on the western side of lake kinneret which is absent on the eastern side groundwaters of the lower jordan valley are chemically different on both sides of the jordan river indicating that the exchange of water is insignificant all saline waters from the dead sea and its surroundings represent a complex mixture of brines and precipitation and local dissolution of halite and gypsum many wells of the arava araba valley pump groundwater from the upper cretaceous limestone aquifer the origin of the water is actually from the lower cretaceous kurnub group sandstones groundwater drawn from the quaternary alluvial fill either originates from kurnub group sandstones eilat 108 yaalon 117 or from altered limestones of the judea group the origin of these waters is from floods flowing through wadis incised into calcareous formations of the judea group on the other hand as a result of step faulting hydraulic contact is locally established between the kurnub and the judea groups aquifers facilitating the inter aquifer flow of the confined kurnub paleowater into the karstic formations of the judea group two periods of neogene brine formation are considered the post messinan inland lagoon resulting in drying up of the sdom sea and the evaporation of the pleistocene samra lake which went further through the stage of lake lisan to the present dead sea for the first period major element hydrochemistry suggests that the saline waters and brines in the jordan dead sea arava valley transform evolved from the gradual evaporation of an accumulating mixture of sea ground and surface water due to the precipitation of carbonates gypsum and halite such an evaporating primary water body was strongly enriched in mg br and b and shows high molar ratios of br cl b cl and mg ca but low na cl ratios the development of the br cl ratio is chemically modelled showing that indeed brine development is explicable that way along with the evaporation brine evaporites formed which are leached by infiltrating fresh water yielding secondary brines with na cl ratios of 1 when primary brines infiltrated the sub surface they were subjected to mg ca exchange in limestones dolomitization and to chloritization and albitization in basic igneous rocks turning them into ca cl brines these tertiary brines are omnipresent in the rift the brines of the late lisan and dead sea were generated by evaporating drainage waters which leached halite gypsum and carbonates from the soil and from the sub surface all these brines are still being flushed out by meteoric water resulting in saline groundwaters this flushing is regionally enhanced by intensive groundwater exploitation in variable proportions the neogene and late lisan lake and recent dead sea brines have to be considered as the most serious sources of salinization of groundwaters in the rift deep seated pre sdom brines cannot strictly be excluded but if active they play a negligible role only

co2 output discharged from stromboli island italy abstract total co 2 output from soil gas and plume discharged from the stromboli island was estimated the co 2 emission of the plume emitted from the active crater was estimated on the basis of the so 2 crater output and c s ratio while co 2 discharged through diffuse soil emission was quantified on the basis of 419 measurements of co 2 fluxes from the soil of the whole island performed by using the accumulation chamber method the results indicate an overall output of 416 t day 1 of co 2 from the island the main contribution to the total co 2 output comes from the summit area 396 t day 1 with 370 t day from the active crater and 26 t day 1 from the pizzo sopra la fossa soil degassing area the release of co 2 from peripheral areas is 20 t day 1 by soil degassing scari area mainly the result of the soil degassing survey confirms the persistence of the highest co 2 degassing areas located on the north east crater side and scari area

geochemical characterisation of gases along the dead sea rift evidences of mantle co2 degassing abstract the dead sea transform dst fault system where a lateral displacement between the african and arabian plates occurs is characterised by anomalous heat flux in the israeli area close to the border with syria and jordan the concentration of he and co2 and isotopic composition of he and total dissolved inorganic carbon were studied in cold and thermal waters collected along the dst in order to investigate the source of volatiles and their relationship with the tectonic framework of the dst the waters with higher temperature up to 57 2 c are characterised by higher amounts of co2 and helium up to 55 72 and 1 91 10 2 cc l 1 respectively helium isotopic data r ra from 0 11 to 2 14 and 4he 20ne ratios 0 41 106 86 show the presence of deep deriving fluids consisting of a variable mixture of mantle and crust end members with the former reaching up to 35 carbon isotope signature of total dissolved carbon from hot waters falls within the range of magmatic values suggesting the delivery of deep seated co2 the geographical distribution of helium isotopic data and isotopic carbon co2 values coupled with co2 3he ratios indicate a larger contribution of mantle derived fluids affecting the northern part of the investigated area where the waters reach the highest temperature these evidences suggest the occurrence of a favourable tectonic framework including a moho discontinuity up rise and or the presence of a deep fault system coupled with the recent magmatic activity recognised in the northern part of israel

geographical distribution of 3he 4he ratios in japan implications for arc tectonics and incipient magmatism the 3he 4he and 4he 20ne ratios of 115 natural gas samples including various types of gases from volcanoes hot springs mineral springs water wells petroleum fields and natural gas fields were measured using a mass spectrometer the observed 3he 4he and 4he 20ne ratios range from 7 47 10 8 to 9 65 10 6 and from 0 26 to 1100 respectively the 3he 4he ratios reflect well the geotectonic structure of the japanese islands in northeastern ne japan there is a clear geographical difference in the 3he 4he ratios between the frontal arc forearc and volcanic arc back arc regions lower ratios were found in the trench side region and higher ratios in the back arc side this result suggests that the mantle derived helium in the volcanic arc region is associated with the diapiric uprise of a magma lower 3he 4he ratios in the frontal arc region may be due to radiogenic he produced by radioactive decay of u and th in the crustal and sedimentary rocks in southwestern sw japan there is no clear geographical contrast in the 3he 4he ratios some samples in the frontal arc region show quite high 3he 4he ratios the tendency of the 3he 4he ratios agrees with the distribution of terrestrial heat flow data and reflects geotectonic structures different from ne japan the high 3he 4he ratios observed in the frontal arc region in sw japan may be indicative of renewed or incipient magmatism due to a descending young and warm slab

geochemistry of dissolved gases from the eastern carpathians transylvanian basin boundary abstract we show the results of a study on the volatiles dissolved in mineral waters discharged over a 200 km long transect along the rodna b rg u area and c limani gurghiu harghita volcanic chain eastern carpathians romania all of the collected mineral water samples carry dissolved gas with carbon dioxide content up to 1 99 cm 3 stp gh 2 o and helium content up to 2 3 10 5 cm 3 stp gh 2 o carbon 13 c tdic total dissolved inorganic carbon ranging from 15 6 to 5 32 vs vpdb he systematics he isotopes in the range of 0 38 0 99 ra ra air normalized 3 he 4 he ratio and co 2 3 he ratio spanning over four orders of magnitude from morb like values of 2 92 10 9 to crustal type values of 3 02 10 13 coherently indicate the presence of fluids from different crustal sources e g sediments hydrocarbon reservoirs besides minor but detectable contributions of mantle magmatic derived fluids up to 16 45 our investigations show that the wide range of chemical and isotopic composition can be explained in terms of mixings among different gas sources feeding the groundwater and the contemporary occurrence of gas water interactions like degassing and deposition of carbonates affecting the circulating waters after their infiltration

origin of carbon in fumarolic gas from island arcs abstract we have measured 3 he 4 he ratios 13c values and co 2 3 he ratios of fumaroles and hot spring gases in three volcanic areas in japan the 3 he 4 he ratios 13c values and co 2 3 he ratios vary from 02 05 ratm 9 7 to 2 7 and from 7 74 109 to 1 18 1011 respectively based on these data and those in the literature we present the first quantitative estimates of the upper mantle sediment and limestone including slab components in co2 of volcanic and hydrothermal fluids from subduction zones taking compiled c isotopic data of limestone and organic sediment assuming that the co 2 3 he ratio and 13c value of mid ocean ridge basalt morb are representative of the upper mantle component and that later isotopic and elemental fractionations are minimal it is possible to deconvole each fraction of c on the basis of simple mixing equations up to 20 of the carbon in high temperature volcanic gases in subduction zones is derived from a morb type source while the major fraction of the gases is attributable to co2 produced by decarbonation of subducted marine limestone and slab carbonate

geochemical characteristics of soil radon and carbon dioxide within the dead sea fault and karasu fault in the amik basin hatay turkey abstract the study area is close to the boundary of three tectonic plates anatolian arabian and african plates and is characterized by important tectonic lineaments which consist mainly of the dead sea fault dsf the karasu fault and the east anatolian fault eaf systems to understand the origin of soil gas emanation and its relationships with the tectonics of the amik basin hatay a detailed soil gas sampling was systematically performed together with co2 flux measurements 220 soil gas samples were analyzed for rn and co2 concentrations the distribution of soil rn kbq m3 co2 concentration ppm and co2 flux g m2 day in the area appears as a point source spot and or diffuses halo anomalies along the buried faults fractures due to crustal leaks the results revealed that rn and co2 concentrations in the soil gas show anomalous values at the specific positions in the amik basin the trace of these anomalous values is coincident with the n s trending dsf co2 is believed to act as a carrier for rn gas based on the rn and co2 concentrations of soil gases at least three gas components are required to explain the observed variations in addition to the atmospheric component two other gas sources can be recognized one is the deep crust component which exhibits high rn and co2 concentrations and is considered the best indicator for the surface location of fault fracture zones in the region the other component is a shallower gas source with high rn concentration and low co2 concentration moreover he isotopic compositions of representative samples vary from 0 94 to 0 99 ra illustrating that most samples have a soil air component and may have mixed with some crustal component without significant input of the mantle component based on the repeated measurements at a few sites soil gas concentrations at the same site were observed to be higher in 2014 than in 2013 which may be associated with the activity of the dsf in 2013 2014 this suggests that soil gas variations at fault zone are closely related to the local crustal stress and hence are suitable for monitoring fault activities

basal heat flow and hydrothermal regime at the golan ajloun hydrological basins summary a shallow heat anomaly in the form of heated groundwater is detected in the lower yarmouk gorge lyg at northern israel and jordan results of 2 d numerical simulations of groundwater flow and heat transfer conducted for the golan ajloun area indicate that satisfying the thermal field observations requires a existence of an exceptional source of geothermal heat below the golan heights gh b existence of a deep flow path 3 km of several mcm yr of the total 45 5 mcm yr forced convection flow component originating at hermon ridge and discharging at the lyg outlets said flow component serves as fundamental heat convection component which transports heat from a great depth and vast area and significantly affects the geothermal pattern this deep circulation is causing a considerable part of the basin s elevated heat to be transported to the lyg outlets preventing shallow thermal expression at the gh model results indicate that regional mean basal heat flow value of the gh is 100 mw m 2 and that the shallow thermal anomaly of the lyg is an expression of a deep crust geothermal anomaly additional possible hydrothermal configurations involve an eastern exceptional heat source or alternatively deep convection that is larger by area magnitude 3600 km 2 and under standard regional basal heat flow 50 mw m 2

gas geochemistry of hot springs at the tengchong field southwest china controlled by the spatial distribution of magmatic chamber abstract the tengchong volcanic field located at the collision zone between the indian and eurasian plates is well known for its large scale holocene volcanic eruptions and extensive hydrothermal activities bubbling gases from eight geothermal springs at the tengchong field were collected and analyzed for their chemical and isotopic compositions 3he 4he 20ne n2 ar 13cch4 and 13cco2 the results show that the gas samples could be categorized into a group i dominated by n2 and a group ii with co2 as major component the air corrected 3he 4he ratios ranged from 0 17 ra to 4 76 ra and the calculated mantle contributions dramatically varied from 1 9 to 77 9 for group ii by contrast an invariant air corrected 3he 4he ratio of about 0 30 ra and a relatively constant mantle contribution of 4 0 to 5 0 was obtained for group i the sampling sites just on top of the magma chamber received significant mantle derived helium and magmatic gas components at the proximal site of the magma chamber 95 magmatic gas contributions the calculated n2 ar ratio of the hydrothermal endmember for group ii sample sites close to the magma chamber was 61 7 66 2 suggesting that the reaction zone temperature is between 223 c and 252 c the influence of the magma chamber decreases with increasing distance of the sampling sites from the chamber apex the sampling sites group i at the marginal area discharge gases with relatively low 3he 4he ratios and magmatic contributions 19 24 the temperature of the reaction zone for this group was estimated to be 74 c based on the n2 ar ratio of 42 this study provided important constraints to relate hydrothermal gas geochemistry directly with the spatial distribution of the underlying magma chamber plain language summary geochemical characteristics of gases discharged from hydrothermal systems are usually affected by deep magmatic processes shallow hot fluids circulation and water rock interactions in the reaction zone in this study we analyzed the gas abundances and isotopic compositions of hydrothermal gas discharged from the yunnan tibet geothermal belt we used a gas mixing model to quantify the contributions of mantle derived magmatic endmember and hydrothermal endmember the 3he 4he ratios magmatic contribution and temperature of the reaction zone decreased significantly with increasing distance from the magma chamber underneath the tengchong field highlighting the intimate relationships between gas transport hydrothermal circulation and the extent of the magma chamber

active faulting in the dead sea rift abstract manifestations of late quaternary and holocene faulting were studied in a 500 km long segment of the dead sea transform rift most prominent are left slip faults whose characteristic physiographic features are recognizable along most of the studied segment where these faults bend or are stepped to the left rhomb shaped grabens or pull aparts are produced forming depressions in the reverse situation compressional features such as pressure ridges domes and folds form positive topographic features such structures are combined on a variety of scales ranging from a few hundred meters long to tens of kilometers normal faults sub parallel to the left slip faults produce a trough like valley along much of the dead sea transform but are most prominent along the margins of the large rhomb grabens e g the dead sea trough they apparently record a small component of transverse extension generally their motion is slow young slip did not occur along some segments during the last few 10 4 y elsewhere throws of 10 20 m at least occurred in this period the dead sea transform is seismically active the instrumental and historic records indicate a seismic slip rate of 0 15 0 35 cm y during the last 1000 1500 y while estimates of the average pliocene pleistocene rate are 0 7 1 0 cm y either much creep takes place or the slip rate varies over periods of a few 10 3 y

flow of mantle fluids through the ductile lower crust helium isotope trends heat and mass are injected into the shallow crust when mantle fluids are able to flow through the ductile lower crust minimum 3he 4he ratios in surface fluids from the northern basin and range province western north america increase systematically from low crustal values in the east to high mantle values in the west a regional trend that correlates with the rates of active crustal deformation the highest ratios occur where the extension and shear strain rates are greatest the correspondence of helium isotope ratios and active transtensional deformation indicates a deformation enhanced permeability and that mantle fluids can penetrate the ductile lithosphere even in regions where there is no substantial magmatism superimposed on the regional trend are local high 3he 4he anomalies indicating hidden magmatic activity and or deep fluid production with locally enhanced permeability identifying zones with high resource potential particularly for geothermal energy development

helium isotopic signature of modern and fossil fluids associated with the corinth rift fault zone greece implication for fault connectivity in the lower crust abstract helium isotopic ratios of modern groundwaters and of fossil fluids trapped in secondary calcites from fault planes have been measured along the southern corinth rift in order to investigate the nature of fluids circulating in these fault zones and to set constraints on tectonic processes responsible for this extension the observed isotopic ratios of modern fluids range from the air composition to moderately radiogenic compositions 0 15 0 4 ra with ra being the atmospheric 3 he 4 he ratio whereas fossil fluids display more radiogenic compositions 0 04 to 0 15 ra suggesting that they have been trapped deeper in the fault zone in the absence of significant atmospheric contamination these compositions result from mixing of a deep radiogenic and hot fluid with cold and shallow air saturated aquifer waters the absence of a mantle he signal in the corinth rift fluids is remarkable and evidences the lack of active volcanic fluids in the basin it further suggests that the fault system is not connected at depth with zones where mantle he might have been trapped at the scale of the corinth rift this observation suggests that faults are rooted in the upper crust if extension results from displacement of the crust above a north dipping shear zone then this shear zone should be relayed at depth through the lower crust by impermeable ductile deformation at a larger scale it appears that basins in the western side of the aegean host crustal helium whereas basins in the anatolian side present systematically mantle he this he isotope distribution is difficult to explain by symmetrical tectonic evolution of the aegean domain and could instead be related to the recent propagation of the north anatolian fault naf propagation of the naf may have recently disturbed hydrothermal circulations established after miocene extension by progressively reactivating the western basins with a different style of tectonic deformation re localising most of the fault controlled flow pathway in shallower basins and as a consequence displacing the fluids mixture toward a crustal origin

adjacent terranes with ca 2715 and 2650 ma high pressure metamorphic assemblages in the nuuk region of the north atlantic craton southern west greenland complexities of neoarchaean collisional orogeny abstract in the gneiss complex of the nuuk region of the north atlantic craton in southern west greenland terrane juxtaposition was followed by neoarchaean folding under amphibolite facies conditions with widespread low pressure recrystallisation 5 kbar and 550 700 c the complex metamorphic overprinting requires that the p t history related to actual terrane assembly has to be extracted from very small relicts of older metamorphic assemblages combined with the u pb dating petrology and geochemistry of metamorphic zircons in the south of the region the faeringehavn terrane eoarchaean orthogneisses is tectonically overlain by a supracrustal package of amphibolites and paragneisses ca 2840 ma felsic volcano sedimentary protoliths this package is juxtaposed against a higher tectonic level represented by the tre brodre terrane 2825 ma orthogneisses and the tasiusarsuaq terrane 2920 2810 ma orthogneisses the terranes were assembled by 2710 2720 ma as shown by dating of granitic sheets intruded along the terrane boundary mylonites in the faeringehavn terrane and in the overlying 2840 ma supracrustal package relict early high pressure assemblages 12 8 kbar 700 750 c are clinopyroxene garnet plagioclase quartz hornblende in mafic rocks and garnet kyanite rutile bearing assemblages in paragneisses these are commonly replaced by lower pressure assemblages 7 5 kbar such as cordierite sillimanite garnet in paragneisses and hornblende plagioclase quartz garnet in mafic rocks in situ partial melting took place during both low and high pressure regimes metamorphic zircon in the high and low pressure assemblages yields dates of ca 2715 ma mostly with errors of the kapisilik terrane 3050 2960 ma orthogneisses and another supracrustal assemblage of amphibolites and ca 2800 ma quartzo feldspathic metasedimentary rocks are exposed north of the faeringehavn terrane and within fold cores along its western margin are bounded by folded neoarchaean mylonites the kapisilik terrane and this supracrustal assemblage include high pressure metamorphic remnants in amphibolites and metasediments metamorphic segregations with garnet clinopyroxene and kyanite respectively that formed at ca 2650 ma these remnants are overprinted by high temperature but lower pressure metamorphic events at ca 2630 2610 and 2580 ma thus remnants of early metamorphism reveal mutually exclusive ca 2715 and 2650 ma high pressure events in adjacent tectonically juxtaposed terranes repeated high pressure metamorphism in adjacent terranes is observed in younger complex collisional orogens

magmatic and metamorphic imprints in 2 9 ga chromitites from the sittampundi layered complex tamil nadu india abstract the ca 2 9 ga old sittampundi layered complex slc of south india belongs to a special group of deformed and metamorphosed archaean rocks where chromitites are interlayered with anorthosite detailed field studies have revealed that the slc comprises of a sequence of magmatic rocks consisting of clinopyroxenite anorthosite and mafic rocks of tholeiitic composition minor bif banded iron formations intercalated with the mafic rocks are the only sedimentary rock within the slc chromitite occurs as continuous to discontinuous bands a few mm up to 6 m thick within clinopyroxenite and highly calcic anorthosite an 99 100 but never in the enclosing mafic rocks chromite occurs broadly in three textural types a cumulus grains in chromitite layers b disseminated grains in clinopyroxenite and anorthosite and c small grains included in clinopyroxene and plagioclase a suite of felsic magma intruded the slc at ca 2 51 ga subsequently the entire rock sequence underwent polyphase deformation and metamorphism at ca 2 50 2 45 ga granulite facies and at 0 72 0 50 ga amphibolite facies during the latter event extensive alteration of clinopyroxene to amphibole and chlorite of plagioclase to clinozoisite and of chromite to cr poor green spinel took place chromite compositions show large variations cr 26 60 mg 4 45 fe 3 2 24 depending upon textural type and nature of the associated phases the most conspicuous compositional variation took place when chromite was metasomatically replaced by green spinel cr 3 21 mg 45 61 during amphibolite facies metamorphism on a cr vs mg plot pristine magmatic compositions of chromite define an array that suggest increasing cr with concomitant decrease in mg presumably during magmatic fractionation highly calcic plagioclase in anorthosite and fe al rich chromite in chromitite in the slc are consistent with a hydrous parental magma of tholeiitic composition this hydrous magma was generated in an oceanic arc environment and crystallized close to the surface of the earth in terms of mineralogy and field relations chromitite bearing rocks of the slc show remarkable similarity with the archaean anorthosite hosted chromitite deposits in layered magmatic complexes at fiskenaesset greenland and messina south africa but contrasts sharply with the chromitite deposits of proterozoic and phanerozoic age a change in the style of arc magmatism appears to be the controlling factor for marked change in chromite compositions across the archaean proterozoic boundary

isotopic chemical and dissolved gas constraints on spring water from popocatepetl volcano mexico evidence of gas water interaction between magmatic component and shallow fluids abstract geochemical research was carried out on cold and hot springs at popocatepetl popo volcano mexico in 1999 to identify a possible relationship with magmatic activity the chemical and isotopic composition of the fluids is compatible with strong gas water interaction between deep and shallow fluids in fact the isotopic composition of he and dissolved carbon species is consistent with a magmatic origin the presence of a geothermal system having a temperature of 80 100 c was estimated on the basis of liquid geothermometers a large amount of dissolved co 2 in the springs was also detected and associated with high co 2 degassing

origin and interactions of fluids circulating over the amik basin hatay turkey and relationships with the hydrologic geologic and tectonic settings abstract we investigated the geochemical features of the fluids circulating over the amik basin se turkey syria border which is crossed by the northern extension of the dsf dead sea fault and represents the boundary area of three tectonic plates anatolian arabian and african plates we collected 34 water samples thermal and cold from natural springs and boreholes as well as 8 gas samples bubbling and gas seepage besides the gases dissolved in the sampled waters the results show that the dissolved gas phase is a mixture of shallow atmospheric and deep components either of mantle and crustal origin coherently the sampled waters are variable mixtures of shallow and deep ground waters the latter being characterised by higher salinity and longer residence times the deep groundwaters from boreholes deeper than 1000 m have a ch 4 dominated dissolved gas phase related to the presence of hydrocarbon reservoirs the very unique tectonic setting of the area includes the presence of an ophiolitic block outcropping in the westernmost area on the african plate as well as basalts located to the north and east on the arabic plate the diffuse presence of co 2 enriched gases although diluted by the huge groundwater circulation testifies a regional degassing activity fluids circulating over the ophiolitic block are marked by h 2 dominated gases with abiogenic methane and high ph waters the measured 3 he 4 he isotopic ratios display contributions from both crustal and mantle derived sources over both sides of the dsf although the serpentinization process is generally independent from mantle type contribution the recorded helium isotopic ratios highlight variable contents of mantle derived fluids due to the absence of recent volcanism over the western side of the basin african plate we argue that co 2 rich volatiles carrying mantle type helium and enriched in heavy carbon are degassed by deep rooted regional faults rather than from volcanic sources

the thermal structure of israel and the dead sea fault abstract in this paper we analyze temperature data from all the available oil and water wells in israel and compare the results with seismicity depth and with heat flux estimation from xenoliths we show that the average heat flux in israel is 40 45 mw m 2 consistent with measurements of the arabian shield a heat flux anomaly exists in northern israel and jordan this could be attributed to groundwater flow or young magmatic activity 100 000 years that is common in this area a higher heat flux exists in southern israel and jordan probably reflecting the opening of the red sea and the gulf of eilat gulf of aqaba and does not represent the average value present in the arabian shield the temperature gradient at the dead sea basin is relatively low resulting in low heat flux 2 and a relatively deep seismicity extending to lower crustal depths in agreement with earthquake depths 2 and at the gulf of eilat 65 mw m 2 results with shallower seismicity 80 mw m 2 could be the result of local heating by magmas or by lithospheric necking and shear heating

fault controlled geothermal fluids of the northern trans mexican volcanic belt a geochemical and isotopic study of the los geysers field valley of queretaro mexico abstract this study focuses on the geochemical and isotopic composition of natural spring waters and gases discharging at los geysers thermal area northern trans mexican volcanic belt tmvb and its relations to the regional tectonic framework water is of na hco3 type and samples were collected at temperatures ranging from 48 c to 98 c and ph from 6 8 to 9 3 stable isotope compositions 10 0 to 8 0 for 18o and 75 6 to 69 7 for d deviate from the global and local meteoric lines suggesting fractionation by steam loss the 87sr 86sr values of the thermal waters range from 0 70664 to 0 70698 indicating that most of the strontium comes from the dissolution of carbonate belonging to the late berriasian to early valanginian in the guanajuato conglomerate group and a minor component of less radiogenic sr from paleogene neogene volcano sedimentary and volcanic rocks solute geothermometers reveal a reservoir temperature around 164 c a mixture between air and hydrothermal co2 composes the bubbling gases helium isotopes data r ra 0 96 1 71 and 4he 20ne ratios 0 53 9 41 reveal that helium is dominated by a radiogenic component with a considerable mantle he contribution up to 20 8 since there is no active volcanism at the northern tmvb mantle he is best explained by transport of volatiles along active faults reaching the crust mantle boundary the conceptual hydrogeochemical model involves a thermal aquifer at 1000 m depth which is recharged by regional meteoric water flow a high thermal gradient 153 c km and fast fluid upflow to the surface along discontinuities related to regional horst and graben tectonics

rate of diffuse carbon dioxide earth degassing estimated from carbon balance of regional aquifers the case of central apennine italy central italy is characterized by an anomalous flux of deeply derived co2 in the western tyrrhenian sector of central italy co2 degassing occurs mainly from focused emissions vents and strong diffuse degassing and thermal springs whereas in the eastern apennine area deep co2 is dissolved in cold groundwaters of regional aquifers hosted by mesozoic carbonate evaporite formations influx of deep co2 into 12 carbonate aquifers 12 500 km2 of the central apennine is computed through a carbon mass balance that couples aquifer geochemistry with isotopic and hydrogeological data mass balance calculations estimate that 6 5 1010 mol yr 1 of inorganic carbon are dissolved in the studied aquifers approximately 23 of this amount derives from biological sources active during the infiltration of the recharge waters 36 comes from carbonate dissolution while 41 is representative of deep carbon sources characterized by a common isotopic signature 13c 3 the calculated deep co2 influx rate ranges from 105 to 107 mol yr 1 km 2 increasing regionally from east to west in the study area

helium isotope variations in turkey relationship to tectonics volcanism and recent seismic activities the distribution of helium isotope ratios in the various tectonic provinces of turkey is examined through a synthesis of previously published data and the results of a recent survey along the north anatolian fault zone nafz following the catastrophic 1999 earthquakes the r ra values where r sample 3he 4he and ra air 3he 4he cover a wide range from 0 05 to 7 87 and the mantle derived helium is clearly identified in most locations the mantle derived component is high 50 of total he in a regions of central and eastern anatolia both of which are associated with historically active volcanoes and b the seismically active west to central segment of nafz while the mantle contribution reaches a maximum at nemrut volcano in eastern anatolia a region of dominantly compressional tectonics and with moderate enthalpy geothermal fields it is relatively low 50 in the western anatolian extensional province even though this region has the highest geothermal potential the average 3he enthalpy ratios estimated for the different provinces suggest lithospheric stretching and rise of the geotherm as the major mechanism of high heat flow yet limited intrusive activity in western anatolia is suggested as the reason for the comparatively low he additions and consequently low 1 7 106 atoms j 3he enthalpy ratios a more extensive magmatic activity appears to be responsible for the greater input of both heat and helium in eastern and central anatolia with intra province 3he enthalpy variations from 3 1 106 atoms j in eastern to 0 25 106 atoms j in central anatolia reflecting the ageing of hydro magmatic systems the relatively high 3he concentrations in low enthalpy waters of northern anatolia 2 8 106 atoms j are particularly significant since there is no evidence of volcanic activity associated with the strike slip motion along the seismically active segment of nafz continuous monitoring of he isotope compositions along nafz should lead to a better understanding of this apparent anomaly as well as the relationship if any between he isotope variations and seismic activities in this region

a review of structural patterns and melting processes in the archean craton of west greenland evidence for crustal growth at convergent plate margins as opposed to non uniformitarian models abstract the archean craton of west greenland consists of many fault bounded eoarchean to neoarchean tectonic terranes crustal blocks these tectonic terranes are composed mainly of tonalite trondhjemite granodiorite ttg gneisses granitic gneisses metavolcanic dominated supracrustal belts layered anorthositic complexes and late to post tectonic granites rock assemblages and geochemical signatures in these terranes suggest that they represent fragments of dismembered oceanic island arcs consisting mainly of ttg plutons tholeiitic to calc alkaline basalts boninites picrites and cumulate layers of ultramafic rocks gabbros leucogabbros and anorthosites with minor sedimentary rocks the structural characteristics of the terrane boundaries are consistent with the assembly of these island arcs through modern style of horizontal tectonics suggesting that the archean craton of west greenland grew at convergent plate margins several supracrustal belts that occur at or near the terrane boundaries are interpreted as relict accretionary prisms the terranes display fold and thrust structures and contain numerous 10 cm to 20 m wide bifurcating ductile shear zones that are characterized by a variety of structures including transposed and redistributed isoclinal folds geometrically these structures are similar to those occurring on regional scales suggesting that the archean craton of west greenland can be interpreted as a continental scale accretionary complex such as the paleozoic altaids melting of metavolcanic rocks during tectonic thickening in the arcs played an important role in the generation of ttgs non uniformitarian models proposed for the origin of archean terranes have no analogs in the geologic record and are inconsistent with structural lithological petrological and geochemical data collected from archean terranes over the last four decades the style of deformation and generation of felsic rocks on outcrop scales in the archean craton of west greenland and the mesozoic sulu orogenic belt of eastern china are similar consistent with the formation of archean continental crust by subduction zone processes

proposed sources of methane along the dead sea transform abstract the concentrations and isotopic compositions of methane higher alkanes dissolved inorganic carbon dic and co 2 were studied in fresh groundwater brines and springs along the dead sea transform dst from the hula valley in the north to the dead sea ds basin in the south although the occurrence of methane along the dst was documented before this is the first time that comprehensive research was conducted on the methane provenance and the post genetic reactions involved the methane stable carbon isotopic composition 13 c ch4 shows a distinct geographic pattern in the northern part of the dst studied in the hula valley and lake kinneret where recent marshy and lacustrine environments exist the methane source seems to be related to intense shallow depth methanogenesis this microbial methane shows low 13 c values in the range of 13 c ch4 between 58 and 72 and high alkane ratios c 1 c 2 c 3 between 100 and 1000 the isotope fractionation co2 ch4 of 1 065 suggests the domination of hydrogenotrophic methanogenesis rather than acetoclastic methanogenesis in the waters of hammat gader and tiberias hot spring whose source is the cretaceous aquifer 13 c ch4 has high values of 28 and 56 respectively with low alkane ratios of 40 in both sites the high 2 h ch4 values of hammat gader in addition to the isotopic composition of the dic and the difference between co 2 and ch 4 reject the possibility of local microbially produced methane and suggest a sub surface thermogenic source of an initial stage of thermal degradation of bituminous chalk of senonian age similarly methane in groundwater from the ds basin is also interpreted to be of thermogenic origin in accordance with the local geology context in the ds basin of buried asphalt and due to the low geothermal gradient in the region it is speculated that methane is produced from slight heating of the asphalts in general it seems that there is a thermogenic methane contribution along the entire dst which is locally masked by high microbial activity in shallow organic rich environments such as lake kinneret and the hula basin

the role of the aquifer in soil co 2 degassing in volcanic peripheral areas a case study of stromboli island italy abstract the peripheral area of stromboli island italy named scari was continuously studied between january 2009 and december 2010 data on soil co 2 flux and the partial pressure of co 2 pco 2 in equilibrium with the thermal aquifer linked to the magmatic system are presented soil co 2 fluxes range from 20 to 370 g m 2 d 1 and have been strongly affected by soil temperature variations soil co 2 flux data were filtered with respect to the soil temperature and the calculated values called residuals were considered to detect changes induced by the magmatic system the pco 2 values change in a wide range from 0 03 to 0 6 atm showing rapid variations the results of this study show that in the volcanic peripheral area the degassing process of soil co 2 is determined not only by the co 2 released directly from the magma but also by gas water interactions in the aquifer the aquifer is able to dissolve the high amount of co 2 discharged by the magmatic system moreover the residuals of co 2 flux diffused from the soil show a delay on the order of 1 month with respect to the pco 2 in equilibrium with the aquifer the soil co 2 flux is therefore not directly linked to the uprising of magmatic co 2 but instead depends on the co 2 discharged from the aquifer which buffers and modulates the volatile changes released by the magmatic system

rediscovery of the mattawa anorthosite massif grenville province quebec we present new field observations and laboratory data confirming the presence of the mattawa anorthosite massif mat whose existence in south central quebec was hinted at more than 35 years ago mat thus represents a newly recognized member of the late to post tectonic 1060 1010 ma andesine anorthosite belt that includes the ch teau richer st urbain and labrieville massifs the dominant rock type at mat is foliated andesine anorthosite or leuconorite and orientations of foliations indicate that the pluton has the shape of a dome mat contains separate core and border zones which are distinguished on the basis of plagioclase composition and concentrations of ga rb sr and ba xenoliths of labradorite anorthosite having ga sr and ba concentrations different from those of the host andesine anorthosites occur sporadically throughout the pluton as well lastly rocks enriched in fe ti and p jotunite oxide apatite gabbronorite nelsonite ilmenitite also occur at mat primarily near the core b

helium and carbon isotopic compositions of thermal springs in the earthquake zone of sichuan southwestern china abstract the origins of gases from hot springs and earthquake activity in the western part of sichuan province southwestern china are discussed in terms of helium and carbon isotopes and energy released by earthquakes 13 c values of co 2 in free and dissolved gases range from 3 34 to 17 09 and 3 he 4 he ratios vary from 1 5 10 8 to 3 63 10 6 the isotopic compositions indicate that carbon dioxide from the hot springs is a mixture of crustal and mantle co 2 and helium is derived from the crust mantle and atmosphere the thermal springs in different earthquake and or fault zones as well as in different parts of the same zone have different values of 13 c and 3 he 4 he the more tectonically active the district is the larger the 13 c and 3 he 4 he values and the greater the frequency of earthquakes this means that more heat energy is derived from the deep earth with upward migration of anatectic fluids in the active tectonic district such as in the kangding district therefore hot spring gases he co 2 etc may be important geochemical markers for determination of seismological and tectonic activity

the baroclinic transport of the antarctic circumpolar current south of africa five hydrographic transects at nominal longitudes 0 e and 30 e and fourteen expendable bathythermograph xbt sections near the former longitude are used to study the baroclinic transport of the antarctic circumpolar current acc between africa and antarctica the bottom referenced geostrophic transport between the subtropical front and the acc southern boundary is 147 10 sv estimating the transport from the xbts using a technique previously employed south of australia proves delicate because of an irregular bathymetry and water mass variations it nevertheless confirms acc transports around 150 sv gathering these and other estimates from the atlantic sector suggests that while north atlantic deep water is injected in the current west of 35 w a partially compensating loss of deep circumpolar water occurs east of this longitude another transport increase from 0 e to 30 e might reflect southward transfer across the subtropical front south of the agulhas retroflection

mantle fluids in the karakoram fault helium isotope evidence abstract the karakoram fault kkf is the 1000 km long strike slip fault separating the western himalaya from the tibetan plateau from geologic and geodetic data the kkf is argued either to be a lithospheric scale fault with hundreds of km of offset at several cm a or to be almost inactive with cumulative offset of only a few tens of kilometers and to be just the upper crustal localization of distributed deformation at depth here we show 3he 4he ratios in geothermal springs along a 500 km segment of the kkf are 3 100 times the normal ratio in continental crust providing unequivocal evidence that a component of these hydrologic systems is derived from tectonically active mantle mantle enrichment is absent along the indus yarlung suture zone isz just 35 km southwest of the kkf suggesting that the mantle fluids flow only within the kkf within the last few ma the kkf must have accessed tectonically active tibetan mantle northeast of the mantle suture which we therefore locate vertically beneath the kkf very close to the surface trace of the isz hence in southwestern tibet indian crust may not now be underthrusting substantially north of the isz even though miocene underthrusting may have placed indian crust north of the isz in the lower half of the tibetan plateau crust this is in significant contrast to central and eastern tibet where underthrust indian material not only forms the lower half of the tibetan crust but is also currently underthrusting for 200 km north of the isz our new constraint on kkf penetration to the mantle allows an improved description of the continuously evolving karakoram fault as a tectonically significant yet perhaps geologically ephemeral lithospheric structure

dissolved helium isotope ratios in ground waters a new technique based on gas water re equilibration and its application to stromboli volcanic system here a new technique for the determination of dissolved he isotope ratios in ground waters is presented this method is based on the extraction and subsequent equilibrium of dissolved gases in an added host gas phase ultra pure n2 is placed in glass flasks 250 cc containing water samples that were hermetically sealed after their collection after shaking in an ultrasonic bath for 10 min an aliquot of the separated gas phase was removed from the flask for ms analysis 3he 4he ratios are measured by using a modified double collector mass spectrometer vg 5400 tft helium and ne concentrations are calculated by comparing the partial pressures of masses 4 and 20 of the samples with those of the air standard measured by a quadrupole mass spectrometer qms vg quartz using he and ne equilibrium partitioning coefficients it is possible to calculate the amount of gas originally dissolved in the water the technique was tested on both air saturated waters asw and thermal waters from stromboli aeolian islands south italy the results of which confirmed good reproducibility 5 and accuracy 3 of the data the method was then applied to three thermal water samples collected from the same volcanic area and the results compared with those of a fumarolic and a soil gas the isotope ratios for dissolved he gave values of 4 06 4 23 ra which are significantly higher than those previously reported in the literature 3 0 3 5 and 2 9 ra and that measured at the fumarole 3 09 ra suggesting a newer and higher isotopic signature for the volcanic system the proposed method appears to be a useful tool in the determination of 3he 4he ratios in ground water systems especially when free gases are not available or are dangerous to collect

helium carbon relationships in geothermal fluids of western anatolia turkey abstract we investigate the helium carbon and oxygen hydrogen isotopic systematics and co2 3he ratios of 8 water and 6 gas samples collected from 12 geothermal fields in western anatolia turkey 3he 4he ratios of the samples r normalized to the atmospheric 3he 4he ratio ra 1 39 10 6 range from 0 27 to 1 67 and are significantly higher than the crustal production value of 0 05 fluids with relatively high r ra values are generally found in areas of significant heat potential kizildere and tuzla fields co2 3he ratios of the samples ranging from 1 6 109 to 2 3 1014 display significant variation and are mostly higher than values typical of an upper mantle source 2 109 the 13c co2 and 13c ch4 values of all fluids vary from 8 04 to 0 35 and 25 80 to 23 92 vs pdb respectively stable isotope values 18o d of the geothermal waters are conformable with the mediterranean meteoric water line and indicate a meteoric origin the temperatures calculated by gas geothermometry are significantly higher than estimates from chemical geothermometers implying that either equilibrium has not been attained for the isotope exchange reaction or that isotopic equilibration was disturbed due to gas additions en route to the surface evaluation of he co2 abundances indicates that hydrothermal degassing and calcite precipitation controlled probably by adiabatic cooling due to degassing significantly fractionate the elemental ratio co2 3he in geothermal waters such processes do not affect gas phase samples to anywhere near the same extent for the gas samples mixing between mantle and various crustal sources appears to be the main control on the observed he c systematics however crustal inputs dominate the co2 inventory considering that limestone is the main source of carbon 70 to 97 of the total carbon inventory the carbon flux from the crust is found to be at least 20 times that from the mantle as to the he inventory the mantle derived component is found to vary up to 21 of the total he content and is probably transferred to the crust by fluids degassed from deep mantle melts generated in association with the elevated geotherm and adiabatic melting accompanying current extension the range of 3he enthalpy ratios 0 000032 to 0 19 10 12 cm3 stp j of fluids in western anatolia is consistent with the release of both helium and heat from contemporary additions of mantle derived magmas to the crust the deep faults appear to have facilitated the deep circulation of the fluids and the transport of mantle volatiles and heat to the surface

carbon dioxide diffuse emission and thermal energy release from hydrothermal systems at copahue caviahue volcanic complex argentina abstract the north western sector of caviahue caldera argentina close to the active volcanic system of copahue is characterized by the presence of several hydrothermal sites that host numerous fumarolic emissions anomalous soil diffuse degassing of co2 and hot soils in march 2014 measurements of soil co2 fluxes in 5 of these sites namely las maquinas las maquinitas i las maquinitas ii anfiteatro and termas de copahue allowed an estimation that 165 t of deeply derived co2 is daily released the gas source is likely related to a relatively shallow geothermal reservoir containing a single vapor phase as also suggested by both the geochemical data from the 3 deep wells drilled in the 1980s and gas geoindicators applied to the fumarolic discharges gas equilibria within the h c o gas system indicate the presence of a large probably unique single phase vapor zone at 200 210 c feeding the hydrothermal manifestations of las maquinas las maquinitas i and ii and termas de copahue a natural thermal release of 107 mw was computed by using co2 as a tracer of the original vapor phase the magmatic signature of the incondensable fumarolic gases the wide expanse of the hydrothermal areas and the remarkable high amount of gas and heat released by fluid expulsion seem to be compatible with an active magmatic intrusion beneath this portion of the caviahue caldera