hydrochemical processes in the lower jordan valley and in the dead sea area abstract changes in the concentrations of major some minor and trace elements occurring in both surface and groundwater of the lower jordan river dead sea drainage basin have been investigated in order to identify the characteristics of the regional aquifers and their recharge areas spider patterns of elements and rare earth distribution patterns pinpoint the characteristic chemical features of groundwater as compared to seawater the high br cl ratios in groundwater are caused either by high br cl ratios in precipitation by leaching of br from bituminous matter or by mixing with brines beyond the epsomite stage the locations of groundwater samples with enhanced b contents coincide with the distribution of gypsum in the beds of the lisan formation which produces water with nearly constant b so 4 2 molar ratios aeolian distribution of the unconsolidated lisan sediments influences the b so 4 ratio in the area of lake tiberias and in the jordan highlands the high gd anomaly in the dead sea water is of geologic origin whereas that in the jordan river and in nahal stream qidron is largely anthropogenic the anthropogenic gd input to the dead sea is insignificant compared to the actual amount in the water of the dead sea hot saline water encountered along the western shores of the dead sea with high gd anomalies indicate that they contain large amounts of ancient dead sea water that mix as hot ascending brines with fresh water the recharge area of groundwater in the lower jordan valley extends largely over limestone and dolomite outcrops of the upper cretaceous judea group weathering of locally underlying lower cretaceous volcanics in the area of pezael beqaot and argaman yield groundwater with 34 s so 4 2 values ranging from 2 to 4 the presence of sulphide bearing bodies in this area is attested to magnetic anomalies detected at depths of several kilometres 34 s so 4 2 indicates very deep groundwater circulation high 34 s so 4 2 15 is typical for marine sulphates from the judea and avedat group limestone the springs located along the northwestern shore of the dead sea discharge water replenished on the eastern judea mountains the increase in the salinity of this water is due to brines flushed from sediments and from adjacent sedimentary rocks which host entrapped brines from the precursors of the dead sea formed during the late stages of lake lisan fresher water flushes out these residual brines as a result of falling sea level salinity increase in groundwater is also affected by the ascent of deep seated hot brines from pre sedom periods along the rift faults calculations of mixing between fresh and highly saline end members show that leaching of anhydrite from sediments precipitation of calcite formation of dolomite albitization of plagioclase and ion exchange with abundant clay minerals control the major element composition of the saline groundwater

burnt bone assemblages from el esquilleu cave cantabria northern spain deliberate use for fuel or systematic disposal of organic waste abstract bones or fossil fuels associated with combustion structures have been widely discussed in several works related to neanderthal lifestyles and subsistence patterns during the mis 3 el esquilleu cave western cantabria spain can significantly contribute to this issue particularly with the taphonomic study of layers 21 and 23 which are characterized by the presence of hearths containing abundant burnt and charred faunal remains of ibex the fragmentation and burning rates as well as bone presence within hearths may suggest that they were used as a supplementary fuel resource following previous research on the suitability of bones as a supplement to firewood in hearth combustions a series of experiments are here presented using goat bones in consistency with the faunal record present at el esquilleu our experiments proved that small sized animal

geochemical evolution of groundwater in carbonate aquifers in taiyuan northern china abstract thirty nine samples of both cold and thermal karst groundwater from taiyuan northern china were collected and analyzed with the aim of developing a better understanding of the geochemical processes that control the groundwater quality evolution in the region s carbonate aquifers the region s karst groundwater system was divided into three geologically distinct sub systems namely the xishan mountain karst groundwater subsystem xmk the dongshan mountain karst groundwater subsystem dmk and the beishan mountain karst groundwater subsystem bmk hydrochemical properties of the karst groundwaters evolve from the recharge zones towards the cold water discharge zones and further towards the thermal water discharge zones in the xmk and the dmk the hydrochemical type of the groundwater evolves from hco 3 ca mg in the recharge flow through zone to hco 3 so 4 ca mg so 4 hco 3 ca mg in the cold water discharge zone and further to so 4 ca mg in the thermal water discharge zone by contrast the water type changes from hco 3 ca mg to hco 3 so 4 ca mg in the bmk with almost invariable tds and temperatures all along from the recharge to the discharge zone the concentrations of sr si fe f and of some trace elements al b li mn mo co ni increase as groundwater temperature increases different hydrogeochemical processes occur in the three karst groundwater sub systems in the xmk and the dmk the geochemical evolution of the groundwater is jointly controlled by carbonate dissolution precipitation gypsum dissolution and dedolomitization while only calcite and dolomite dissolution precipitation occurs in the bmk without dedolomitization the hydrogeochemical data of the karst groundwaters were used to construct individual geochemical reaction models for each of the three different karst groundwater sub systems the modeling results confirm that dedolomization is the major process controlling hydrochemical changes in the xmk and the dmk in the thermal groundwaters the dissolution rates of fluorite siderite and strontianite were found to exceed those of the cold karst groundwater systems which can explain the higher concentrations of f fe and sr 2 that are found in these waters

the influence of melting and melt drainage on crustal rheology during orogenesis partial melting significantly weakens crustal rocks by introducing a low viscosity liquid phase however near concomitant melt drainage can remove this weak phase potentially reversing the rheological effects such that the strength of a specific lithology depends on when the prograde pressure temperature path intersects a melting reaction how much melt is produced and how long this melt is retained before it is lost phase equilibria and mixed rheology modeling of typical metapelite and metagreywacke compositions indicate that these rocks undergo continuous but pulsed melt production during prograde metamorphism depending on whether melt removal is continuous or episodic and assuming geological strain rates the lithologies can retain a very low strength less than 1 mpa or transiently strengthen to 5 mpa following melt loss lithologies undergoing episodic melt loss can therefore cycle between being relatively weak and relatively strong components within a composite crustal section melt production retention and weakening in the middle to lower crust as a whole is more sustained during heating and melt production consistent with geodynamic inferences of weak melt bearing lower crust however the long term consequence of melting and melt loss is a 50 400 increase in the strength of residual lithologies the strengthening is more pronounced in metapelite than metagreywacke and is achieved through a combination of dehydration and the removal of the weak mica framework coupled to increased proportions of strong feldspars and garnet despite prolonged weakness melting and melt loss therefore ultimately result in a dry and elastic lower crust

stratigraphic correlation of the neogene basins in southwestern anatolia regional palaeogeographical palaeoclimatic and tectonic implications abstract the extensional intramontane grabens that formed in southwestern anatolia in the late cenozoic bear the unique tectono sedimentary palaeontological and palynological record of a region that underwent rapid transition from the last compressional pulses of the alpine orogeny to the tectonic phase of orogen collapse and the onset of neotectonic regime the change in tectonic regime was accompanied by regional climatic changes recorded by the sedimentary environments of the basins and evidenced by palaeontological and palynological data the late early to mid middle miocene was characterized by a warm and humid subtropical climate with densely forested wetlands the late middle to late miocene witnessed a change to arid climatic conditions with grass dominated steppe ecosystems the pliocene climate was warm and humid with savannah type open habitats in terms of their stratigraphic development the southwestern anatolian basins form two distinct groups one group is represented by the denizli soke and yatagan basins which commenced their development in the early burdigalian and underwent similar phases of environmental change 1 the burdigalian phase of alluvial environment and redbed deposition 2 the late burdigalian langhian phase of alluvial sedimentation accompanied by the formation of terminal lakes 3 the serravallian middle tortonian phase of the formation of shallow perennial lakes 4 the middle tortonian messinian phase of lake expansion and deepening followed by shrinking and shallowing 5 the pliocene phase of lake expansion and deepening and 6 the erosional quaternary phase of two stage alluvial sedimentation separated by a high relief erosional unconformity the other younger group of tectonic grabens is represented by the karacasu bozdogan cameli and esen basins which commenced their development in the earliest tortonian and underwent common environmental changes 1 the tortonian phase of alluvial environment and redbed deposition coeval with the phase of lake drying in the denizli soke and yatagan basins 2 the messinian phase of the formation of terminal lakes coeval with the re establishment of shallow lakes in the three other basins 3 the zanclean phase of shallow perennial lakes coeval with the expansion and deepening of lakes in the other basins 4 the piacenzian phase of deep lacustrine environments 5 the gelasian phase of shallow lacustrine environments and 6 the erosional quaternary phase of two stage alluvial sedimentation similar as in the other basins in spite of the time offset in their development the two basin groups have been strongly modulated by climate and hence show correlative responses to regional climatic changes despite the time offset in their tectonic development the two basin groups showed correlative environmental changes imposed by regional climatic conditions the basins were environmentally unified by the quaternary alluvial phase of their development in the late cenozoic anatolia was at the crossroads of fauna migration routes between africa asia and europe and the palaeontological data from the southwestern anatolian basins shed more light on this phenomenon the study as a whole contributes to a better understanding of the late cenozoic environmental climatical and biogeographical changes in the eastern mediterranean

rheological transitions in progressive melting of rock and their geological constraints from the fuhu metatexite diatexite profile in guangdong province se china abstract integration of the published experimental data of partially melted amphibolite orthogneiss granite and aplite reveals the existence of three rapid strength drops of the rock assemblage at melt fraction around 7 21 and 41 respectively the first and the last drops are equivalent to the well known melt connectivity transition mct and solid to liquid transition slt the drop at melt fraction around 21 is newly identified and termed as the framework melting transition fmt the fmt is defined as the transition from eutectic quartz feldspars melting to refractory biotite melting the three rheological transitions are well constrained by the geological data from the fuhu profile in guangdong province se china this profile is a 15 m high cliff rocks exposed on the profile are zoned as mottled stripped narrow banded and wide banded migmatites and diatexitic granite from the top of the profile downwards the leucosome proportions of the zones measured on the outcrops combined with the experimental data of the partially melted rocks have significant implications for understanding the role of rheological transitions during crustal melting the mct which corresponds to the boundary between the mottled and the narrow banded migmatites suggests the segregation of melt within the partially melted system along with the compaction of matrix thus the mct is deemed to be the transition of the partially melted system from matrix supported melt stored in pore space to framework supported melt stored in foliation bedding space of protolith the fmt corresponding to the boundary between the narrow and the wide banded migmatites denotes the inception of melting of the solid framework mechanically the fmt can be regarded as the transition of the framework from compaction to fusion and geochemically the transition from eutectic melting of quartz feldspars to that of refractory biotite the increasing melt due to framework melting after the fmt is basically limited within the solid framework until the melt fraction exceeding the slt the slt is geologically constrained by the in situ metatexite diatexite transition that is also termed as magma interface mi the slt mi represents the upper limit of a crustal magma layer because of the downward increasing temperature and melt fraction there should be no consecutive layer of felsic rock existed in the space between the slt mi and the mafic lower crust except the isolated rock blocks within the magma layer

paleoenvironmental evolution of the late pliocene early pleistocene fluvio deltaic sequence of the denizli basin sw turkey abstract the late pliocene early pleistocene tosunlar succession denizli basin southwestern turkey represents fluvial dominated delta environments at the margins of a brackish long lived lake two main facies associations are documented i a delta front facies association with a distal df1 and proximal df2 deposits and ii a delta plain facies association that contains distributary channel dp1 and interdistributary swamp dp2 deposits the stable isotopic analysis of the mollusc faunas exhibit a narrow range of values 4 68 18 o 13 c 18 o 13 c correlation r 0 16 may indicate hydrologically open lake and significant diagenetic alteration the mollusc faunas and their stable isotope ratios show a biogeographically isolated brackish lake system under semiarid climatic conditions under special environmental conditions the endemic faunal composition remained constant which is very unusual for a semi isolated long lived lake setting

comparison of the quaternary travertine sites in the denizli extensional basin based on their depositional and geochemical data abstract in the denizli basin turkey located in the western anatolian extensional province travertine and tufa deposition has been an ongoing process for at least 600 000 years travertine bodies which are 30 to 75 m thick and each covers areas of 1 to 34 km2 are up to 1 km3 in volume today spring waters in this area have temperatures of 19 to 57 c are of the ca mg hco3 so4 type in the pamukkale kelkaya and pinarbasi areas and the ca mg so4 hco3 type at cukurbag thermal waters along the northern margin of the basin are generally hotter than those in the east southeast and south the 18o and d values of the spring waters indicate a meteoric origin the average temperatures of the hydrothermal systems in the denizli basin appear to have decreased from pleistocene to holocene travertine which formed from the hotter water is more widespread than the tufa that formed in the cooler spring waters deposition of the travertine which formed largely on slopes in depressions and along fissure ridges mostly on northern basin margins was controlled by the interplay between various intrinsic and extrinsic parameters the travertines are formed largely of calcite with only minor amounts of aragonite in some of the vertically banded crystalline crust raft and pisoid travertines found in some of the northern sites the aragonitic samples rich in sr are typically found around the spring orifices and along the central axis of the fissure ridges the stable isotope values of the travertine found in the northwest and southeast parts of the basin are different the 13c values of the northern travertine deposits are more positive 3 7 to 11 7 vpbd than those found in the south southeast areas 4 to 5 8 vpdb in contrast the travertine and tufa in the southeastern areas have higher 18o values 15 2 to 7 8 vpdb than those of the northern areas 16 6 to 4 8 vpdb available evidence indicates that spring activity and associated travertine precipitation in the denizli basin were controlled largely by tectonic activity rather than by climatic conditions

a sequence of partial melting reactions at mt stafford central australia metasedimentary gneisses show a rapid change in grade in a 10 km wide low p high t regional aureole at mt stafford in the arunta block central australia migmatite occurs in all but the lowermost of five metamorphic zones which grade from greenschist zone 1 through amphibolite zones 2 3 to granulite facies zones 4 5 the sequence of partial melting reactions inferred for metapelitic rocks is dependant upon protolith temperature and fluid conditions the metapelite solidus in zone 2 reflects vapour present melting at p 3 kbar and t 640 c melting having initially been controlled by the congruent breakdown of the assemblage crd kfs bt qtz at slightly higher temperature andalusite in leucosome formed via the reaction kfs qtz bt h2oand melt and melt having been stabilized by the presence of boron sillimanite coaxially replaces andalusite in the high grade portion of zone 2 in zone 3 large aluminosilicate aggregates in leucosome are armoured by spl crd grt symplectites garnet partially pseudomorphs biotite cordierite or spinel in high grade portions of zone 3 zone 4 grt crd opx bearing metapsammite assemblages and garnet bearing leucosome reflect t 800 c and p 2 2 0 9 kbar in the model kfmash system the principal vapour absent melting step reflected significant modal changes related to the breakdown of the as bt tie line and the establishment of the spl crd tie line the bulk rock geochemistry of migmatite samples straddle the spl crd tie line the aluminous bulk rock composition of the common bedded migmatite restricted its potential to witness garnet forming and orthopyroxene forming reactions minor textural and modal changes in and above zone 3 reflecting biotite destablization in biotite poor assemblages

stable isotope geochemical study of pamukkale travertines new evidences of low temperature non equilibrium calcite water fractionation abstract in this paper we present the first detailed geochemical study of the world famous actively forming pamukkale and karahayit travertines denizli basin sw turkey and associated thermal waters sampling was performed along downstream sections through different depositional environments vent artificial channel and lake terrace pools and cascades of proximal slope marshy environment of distal slope 13 c travertine values show significant increase from 6 1 to 11 7 pdb with increasing distance from the spring orifice whereas the 18 o travertine values show only slight increase downstream from 10 7 to 9 1 pdb mainly the co 2 outgassing caused the positive downstream shift 6 in the 13 c travertine values the high 13 c values of pamukkale travertines located closest to the spring orifice not affected by secondary processes suggest the contribution of co 2 liberated by thermometamorphic decarbonation besides magmatic sources based on the gradual downstream increase of the concentration of the conservative na k cl evaporation was estimated to be 2 5 which coincides with the moderate effect of evaporation on the water isotope composition stable isotopic compositions of the pamukkale thermal water springs show of meteoric origin and indicate a local meteoric water line of denizli basin to be between the global meteoric water line craig 1961 and western anatolian meteoric water line imsek 2003 detailed evaluation of several major and trace element contents measured in the water and in the precipitated travertine along the pamukkale mm section revealed which elements are precipitated in the carbonate or concentrated in the detrital minerals former studies on the hungarian egerszalok travertine kele et al 2008a b 2009 had shown that the isotopic equilibrium is rarely maintained under natural conditions during calcite precipitation in the temperature range between 41 and 67 c in this paper besides the detailed geochemical analyses along downstream sections we present new evidences of non equilibrium calcite water fractionation in lower temperature range 13 3 to 51 3 c our measurements and calculations on natural hot water travertine precipitations at pamukkale and egerszalok revealed that the 18 o travertine is equal with the 18 o hco3 at the orifice of the thermal springs which means that practically there is no oxygen isotope fractionation between these two phases high rate of co 2 degassing with rapid precipitation of carbonate could be responsible for this as it was theoretically supposed by o neil et al 1969 thus for the determination of the deposition temperature of a fossil travertine deposit we propose to use the water bicarbonate oxygen isotope equilibrium fractionation instead of the water travertine fractionation which can result 8 9 c difference in the calculated values our study is the first detailed empirical proof of o neil s hypothesis on a natural carbonate depositing system the presented observations can be used to identify more precisely the deposition temperature of fossil travertines during paleoclimate studies

experimental deformation of partially molten westerly granite under fluid absent conditions with implications for the extraction of granitic magmas the mechanical behavior of partially molten westerly granite was investigated in the temperature range 800 1100 c 250 mpa confining pressure by means of constant strain rate creep and stress relaxation tests the only water in the samples came from the breakdown of hydrous phases biotite minor chlorite and muscovite and alteration products of feldspars thus the amount of melt was controlled by the test temperature and ranged from 3 at 800 c to 50 at 1100 c over that temperature range strength decreased from 500 mpa to less than 1 mpa and a preliminary constitutive flow law for the partially molten rock was obtained to allow extrapolation to low strain rates the comparative viscosity of the melt alone was estimated at 950 and 1000 c from the distance it could be made to penetrate into a porous sand under a known pressure gradient under all conditions deformation of the matrix of solid grains was by brittle fracture only samples containing up to 10 vol melt failed with the formation of a shear fault zone at higher melt fractions melt filled pores collapsed by shear enhanced compaction squeezing the melt into axial cracks above 40 vol melt unfractured solid grains were carried about passively in the flowing liquid there was no evidence of a rheologically critical melt percentage in this system by analogy with the uniaxial compaction of water saturated soils a simple model is erected to describe a two stage process for the extraction of granitic melts from their protoliths with the aid of nonhydrostatic stress shear enhanced compaction is inferred to drive melt into a network of melt filled veins whereupon porous flow through the high permeability vein network allows rapid drainage of melt to higher crustal levels

origin and evolution of two contrasting thermal groundwaters co2 rich and alkaline in the jungwon area south korea hydrochemical and isotopic evidence in the jungwon area south korea two contrasting types of deep thermal groundwater around 20 33 c occur together in granite compared to shallow groundwater and surface water thermal groundwaters have significantly lower 18o and d values 1 lower in 18o and negligible tritium content mostly 2 tu suggesting a relatively high age of these waters at least pre thermonuclear period and relatively long subsurface circulation however the hydrochemical evolution yielded two distinct water types co2 rich water pco2 0 1 to 2 atm is characterized by lower ph 5 7 6 4 and higher tds content up to 3300 mg l whereas alkaline water pco2 10 4 1 10 4 6 atm has higher ph 9 1 9 5 and lower tds 254 mg l carbon isotope data indicate that the co2 rich water is influenced by a local supply of deep co2 potentially magmatic which enhanced dissolution of silicate minerals in surrounding rocks and resulted in elevated concentrations of ca2 na mg2 k hco3 and silica under lower ph conditions in contrast the evolution of the alkaline water was characterized by a lesser degree of water rock granite interaction under the negligible inflow of co2 the application of chemical thermometers indicates that the alkaline water represents partially equilibrated waters coming from a geothermal reservoir with a temperature of about 40 c while the immature characteristics of the co2 rich water resulted from the input of co2 in na hco3 waters and subsequent rock leaching

strain partitioning during partial melting and crystallizing felsic magmas abstract the rheology of partly molten felsic systems changes dramatically during the onset of melting and through crystallization solid to liquid and liquid to solid transitions are not rheologically identical contradicting the concept of a unique rheological critical melt percentage we use four thresholds separating the successive stages according to the melt fraction for the melting transition 1 the liquid percolation threshold connects the melt pockets at about 8 of melt thus allowing local magma displacement at the metric scale and 2 for greater melt percentages 20 25 a melt escape threshold corresponds to the onset of transport over large distances of the melt and part of the residual solid phase leading ultimately to granitic bodies for the solidification transition 3 the first formation of a rigid framework of crystals which can accumulate stress although the melt can still flow corresponds to the rigid percolation threshold 55 solids and 4 the system becomes totally locked at about 72 75 solid which corresponds to the particle locking threshold the present paper focuses on strain partitioning induced by the coexistence of two contrasting rheological phases between these thresholds on a variety of scales non coaxial deformation is preferentially accommodated by the lower viscosity melt which increases the vorticity in the melt phase and reinforces asymmetries in the flow pattern strain partitioning also increases the scale length of the weakest phase during melting and magma ascent whereas strain partitioning decreases the scale length during crystallizing strain partitioning also affects the migration of melt by raising the particle locking threshold and lowering the melt escape threshold for three dimensional deformations such as transpression the direction of melt segregation e g horizontal may differ from the direction of melt migration e g vertical

an experimental deformation study of partially molten amphibolite application to low melt fraction segregation an amphibolite has been experimentally deformed under subsolidus and partially molten conditions to evaluate the influence of melt on the mechanical behavior of a natural mafic rock and to assess low melt fraction segregation processes experiments were performed under fluid absent conditions at 1 8 gpa between temperatures of 650 c and 1000 c these conditions are similar to those of thickened lower continental crust or intermediate depths in subducting oceanic lithosphere at 850 c melt is granitoid in composition and its viscosity is that of wet granite 103 105 pa s the results can be summarized as follows 1 under subsolidus conditions tests at 650 c and 750 c the amphibolite is macroscopically ductile and deformation is homogeneously distributed throughout the sample 2 at near solidus conditions 800 c 0 5 vol melt fractures 1 10 m in width displace hornblende and plagioclase grains and melt formed in situ is found in some of these cracks the formation of a ductile shear zone in one sample is attributed to the presence of very fine grained reaction products from combined dehydration hydration reactions that involve plagioclase the dehydration reaction products have apparently changed the deformation mechanism and even overrode the melt embrittlement process trapping melt in pockets of lower strain with higher melt fractions 10 15 vol broad melt bearing shear zones form and grains within these zones are brittlely deformed 3 at 20 vol melt 1000 c additional weakening occurs but fractures are not observed and the overall deformation is by viscous flow the results show that at low melt fractions 15 vol fluid absent melting reactions can induce fracture in previously ductile rocks this suggests that the percentage at which melt may escape by fracture is lower than the theoretical critical melt fraction or cmf of 26 40 vol in general estimating the fraction of melt at the onset of segregation cannot be predicted by the cmf melt segregation models have to be adapted to variations in such major factors as pressure temperature type of melting reaction rate of melting and strain rate such models will greatly assist our understanding of continental growth and evolution during orogenesis

origin and evolution of the thermal waters from the pamukkale geothermal field denizli basin sw anatolia turkey insights from hydrogeochemistry and geothermometry abstract the pamukkale geothermal field pgf of the denizli basin sw turkey is one of the most distinguished active geothermal fields known in the world the thermal waters from the pgf are subdivided into two groups group 1a ca hco3 and group 1b ca so4 types the cold waters are also classified into two groups group 2a ca hco3 and group 2b mg hco3 types the hydrogeochemical properties of the pgf thermal waters suggest interactions with the basal metamorphic rocks of the menderes massif tectonically overriding by the carbonate rocks of the lycian nappes and sedimentary rocks of the neogene formations the bedrock units are stratigraphically overlain by the neogene sedimentary units of the denizli group the thermal springs of the pgf are affected by several hydrothermal processes including mixing water rock interaction and input of mantle volatiles the thermal water plots of the pgf deviate from the full equilibrium line indicating a low water maturity and or mixing processes mixing models and na k mg ternary diagram suggest mixing between meteoric and thermal waters during the uprising of the deep originated fluids the water rock interaction leads saturation of calcite and induces travertine precipitation in the discharge area low tritium this study proposes a conceptual hydrogeological hydrogeochemical tectonic model for the pgf the thermal waters are derived from the infiltration of rainwater through fractures and faults in high recharge areas to the deep hot reservoir heating produced by the high geothermal gradient is interpreted in relation with the regional crustal thinning thermal waters upwell along wnw ese trending deep faults and fractures the pamukkale fault system that act as hydrothermal pathways favouring migration of a huge amount of co2 rich gas from deep geothermal reservoir the geochemical and isotopic data of the thermal waters and gas indicate that the degassing of both metamorphic co2 and mantle derived co2 occurs in the pgf helium isotope data indicate that mantle volatiles produce possibly an upwelling into asthenosphere and ascent along these tectonic discontinuities in this context the pgf is one of the best example of geothermal fields as an interaction of active magmatism in the actively extending crustal setting

plateau versus fissure ridge travertines from quaternary geothermal springs of italy and turkey interactions and feedbacks between fluid discharge paleoclimate and tectonics abstract morphologically different deposits of thermal travertines are known worldwide but what factors controlled their morphology volume and growth for tens of thousands of years is only partially understood two main morphotypes of quaternary thermal travertines are reconsidered here to understand the reasons for their differential growth the fissure ridge travertines of denizli basin western turkey and the travertine plateau of tivoli central italy for comparable longevities and average vertical deposition rates the main differences between the studied travertines are as follows 1 volume of the travertine plateau is about one hundred times larger than each fissure ridge 2 despite a larger volume the travertine plateau does not produce relief whereas the fissure ridges produce a characteristic prominent topography 3 the travertine plateau grew primarily through lateral progradation whereas the fissure ridges through vertical aggradation 4 travertine deposition occurred in different environments principally low energy flat or shallow environments at tivoli and high energy inclined environments at denizli 5 the growth of the tivoli plateau occurred in a subsiding basin whereas the fissure ridges were not influenced by significant subsidence 6 c and o isotope signatures from the two studied travertines are different 7 despite similar annual precipitations the present water discharge in the tivoli area is about ten times greater than that of the denizli basin u series ages from the two deposits are correlated with paleoclimate oscillations at regional and global scales geological field evidence together with paleoclimate correlations suggest that in both the study cases the main body of travertine deposits the bedded travertine grew preferentially when the water table was high warm and or humid periods conversely when the water table was depressed cold and or dry periods the tivoli travertine underwent partial erosion and the denizli ridges were cut by axial veins and lateral sill like structures filled by banded sparitic travertine a comparative model is proposed where the main factor driving the difference in the morphostratigraphic architecture of fissure ridges and travertine plateaus is the volume of water discharge a high discharge rate resulted in the precipitation of caco3 far away from the springs hence driving the lateral progradation of the tivoli plateau a reduced discharge rate caused travertine precipitation close to the springs thus causing the vertical aggradation of the denizli fissure ridges paleoclimate oscillations must have controlled the amount of fluid discharge which in turn must have influenced the opening of the feeding fractures by an increased pore pressure

analysis of co2 leakage through low permeability faults from natural reservoirs in the colorado plateau east central utah the numerous co 2 reservoirs in the colorado plateau region of the united states are natural analogues for potential geologic co 2 sequestration repositories to better understand the risk of leakage from reservoirs used for long term underground co 2 storage we examine evidence for co 2 migration along two normal faults from a reservoir in east central utah co 2 charged springs geysers and a hydrocarbon seep are localised along these faults these include natural springs that have been active for long periods of time and springs that were induced by recent drilling the co 2 charged spring waters have deposited travertine mounds and carbonate veins the faults cut siltstones shales and sandstones and the fault rocks are fine grained clay rich gouge generally thought to be barriers to fluid flow the geologic and geochemical data are consistent with these faults being conduits for co 2 to the surface consequently the injection of co 2 into faulted geologic reservoirs including faults with clay gouge must be carefully designed and monitored to avoid slow seepage or fast rupture to the biosphere

hydrothermal co2 degassing in seismically active zones during the late quaternary natural co2 discharges are abundant in turkey as evident from ongoing deposition of recent terrace mound travertines and emplacement of significant travertine vein and breccia deposits in fractured damage zones of active fault systems we report high precision u series age data for the vein carbonates combined with important field observations and geochemical data to evaluate the travertine veining and co2 degassing history in seismically active areas field evidence suggests that travertine filled veins and associated breccias represent hydrothermal eruption products which probably formed by hydraulic fracturing in response to overpressure of co2 rich fluids stable isotope and ree data support the field observations and indicate that travertine veins formed as thermogene deposits from rapidly ascending co2 rich fluids travertine veins from the kirsehir geothermal field give u series ages in a range from 10 6 0 3 ka to 86 16 1 24 ka with a majority of ages failing between 10 6 0 3 and 11 3 0 2 ka vein samples from the pamukkale geothermal field yield u series ages between 21 1 0 1 ka and 73 6 0 6 ka two major age groups are evident in pamukkale that cluster coherently around 21 ka and 25 ka a large number of travertine veins we dated by high precision u series technique coincide with times of cold dry climate events this is different from surface sinter deposits in geothermal fields which more frequently form during warm and wet periods we propose that a significant reduction in surface discharge of co2 by spring or geothermal waters during dry climate periods may promote oversaturation of co2 in deep reservoirs host rock fracturing in response to seismic shaking and fluid overpressure results in rapid exsolution and expansion of the dissolved gas and may lead to hydrothermal eruptions crown copyright c 2009 published by elsevier b v all rights reserved

noble gas isotopes and the chemical composition of geothermal gases from the eastern part of the buyuk menderes graben turkey abstract we present noble gas isotope and gas composition data from eight production wells of the kizildere geothermal field and from six gas discharging pools from the adjacent tekke hamam geothermal field situated in the eastern segment of the buyuk menderes graben system in western anatolia turkey gas from both locations is composed mainly of co 2 with minor contributions of n 2 h 2 s ch 4 o 2 ar h 2 c 2 and he with higher contents of h 2 s he and c 2 in tekke hamam samples air corrected helium isotope ratios reveal a mantle origin for samples from both locations but 3 he 4 he ratios are lower and more variable at kizildere 0 96 2 06 r a than at tekke hamam 2 36 2 91 r a r a is the atmospheric 3 he 4 he ratio of 1 39 10 6 kizildere gas contains less 4 he 0 7 2 2 ppmv and 3 he 2 5 10 6 ppmv than gas from tekke hamam 2 5 3 5 ppmv and 1 10 5 ppmv respectively co 2 3 he ratios of 2 8 10 11 at kizildere and 0 7 1 10 11 at tekke hamam are higher than average mantle values 2 10 9 within the kizildere geothermal field reservoir temperatures and co 2 3 he and ch 4 c 2 h 6 ratios increase and 3 he 4 he ratios decrease from southwest to northeast interpolation of a linear trajectory between 3 he 4 he and temperature from kizildere delivers temperature of 173 c 184 c for the source reservoir of tekke hamam in good agreement with measured reservoir temperatures from well th 2 at tekke hamam 171 c the low helium content the variable helium isotope composition and the higher co 2 3 he ratios at kizildere can be explained by temperature dependent partial removal of mantle derived helium e g through vapor separation followed by addition of radiogenic helium kizildere samples derive from the remaining water phase after gas separation while tekke hamam samples may represent the gas phase liberated by the former process the pristine 3 he 4 he ratio of helium at kizildere can be calculated as 2 2 r a close to helium isotope ratios observed at tekke hamam partial removal of helium may also account for the higher and t dependent co 2 3 he ratios at kizildere compared to tekke hamam but such process alone cannot explain the overall high co 2 3 he ratios 7 10 10 and calls for contribution of co 2 from interaction between geothermal fluids and carbonate reservoir rock noble gas abundances indicate mixing with cold meteoric water in the reservoir

from palaeotectonics to neotectonics in the neotethys realm the importance of kinematic decoupling and inherited structural grain in sw anatolia turkey abstract in order to asses young i e neotectonic fault kinematics and the relation with plate tectonic processes in sw turkey we focused on the questions 1 what produced the structural grain i e how and when are faults generated 2 what was is the kinematic behaviour of these faults and 3 during which period s were these faults active firstly the distribution of faults has been investigated using a lineament analysis performed on satellite imagery and digital elevation models we define five main tectonic domains in sw turkey 1 and 2 the northern and southern western anatolian extensional provinces 3 the eastern hellenic arc including rhodes island and the submarine anaximander mountains 4 the lycian taurides and 5 the western limb of the isparta angle lineament analysis reveals dominance of three lineament groups i e nne ene and wnw trending in all identified domains variations in the relative importance of lineament groups exist and are attributed to the specific tectonic evolution of each domain a synthesis of recently published field data shows that the onset of activity of related fault groups is neither synchronous nor uniform the structural grain for the neotectonic deformation in sw turkey is formed during the last stage of palaeotectonic deformation stage 1 which is dominated by the onset of the menderes massif exhumation along a top n major detachment the datca break away fault seyitoglu g isik v and cemen i 2004 complete tertiary exhumation history of the menderes massif western turkey an alternative working hypothesis terra nova 16 358 364 and related se ward sliding of the lycian nappes in the footwall of this fault this stage is characterized by spatially variable types of deformation that are delineated by from nw to se the datca fault around the menderes lycian contact zone and the lycian frontal thrust zone respectively the kinematic decoupling along these structures explains the co existence of top n detachment type extension in the western anatolian extensional province and ongoing nappe emplacement and piggy back development in the lycian taurides the decoupling also explains the lateral complexity of deformation associated with later neotectonic deformation from late miocene onward stage 2 nne ssw extension dominated the western anatolian extensional province influenced by combined anatolian extrusion and hellenic subduction roll back contemporaneously bidirectional ese wnw and nne ssw extension controls the lycian taurides due to the effects of hellenic arc expansion superposed on extrusion roll back extension the zone of kinematic decoupling is characterized by structural complexity with local transpressional features during stage 3 post late pliocene the same types of extension prevail in the western anatolian extensional province and the lycian taurides although a third tectonic regime becomes gradually more important this regime is associated with a tectonic escape in the hellenic arc that induced forearc slivers to be sheared of the expanding arc along mostly sinistrally displacing ene trending strike slip zones several of these zones have been identified in the coastal zones of sw turkey either through recent seismicity or field observations and are especially focused in the lycian taurides domain here they form what is classically referred to as the fethiye burdur fault zone which becomes gradually penetrated from the sw by oblique or strike slip zones exemplifying the time transgressive nature of the tectonic escape mechanism zones of kinematic decoupling remain persistent throughout the entire early miocene recent tectonic evolution of sw turkey and explain the existence of differently deforming tectonic domains

source of arsenic based on geological and hydrogeochemical properties of geothermal systems in western turkey abstract turkey is an area of complex geology with active tectonics and high geothermal potential especially the western part of turkey is a region of abundant geothermal activity faults accommodating the deep circulation of hydrothermal fluids of meteoric origin are the primary means by which of geothermal systems are controlled in this region many of the thermal activities are related to the improved dilation on the e w strikes of the graben faults this situation serves as a suitable environment for the presence of high levels of arsenic in geothermal water resources the highest concentrations of naturally occurring aqueous arsenic as are found in certain types of geothermal waters generally those related to major graben faults in this regard high arsenic concentrations in geothermal resources have been detected in western turkey including but not limited to biga peninsulla gediz graben kucuk and buyuk menderes graben with values ranging from 1 to 1419 ppb in geothermal fluids the thermal waters have surface temperatures of up to 100 c and reservoir temperatures range from 150 to 248 c in the menderes graben from 120 to 287 c in the gediz graben and from 153 to 174 c in biga peninsula hydrogeochemically the menderes graben and gediz graben thermal waters are of the na hco 3 ca hco 3 and na so 4 types whereas some geothermal fluids such as those of tuzla and kestanbol in the biga peninsula cesme and urla are of the na cl type

the ad 60 denizli basin earthquake and the apparition of archangel michael at colossae aegean turkey this paper illustrates the results of a multidisciplinary study on the active tectonics of hierapolis and colossae in aegean turkey tectonic analysis is combined with a study of historical seismicity highlighting the use of historical sources from oral tradition legends and myths to derive important geological information for which the legendary account is the only witness strong correlation between tectonic and historical mythological data suggests that the legendary narration is based on real geological events this allows a better understanding of the local active tectonics and seismic history at hierapolis it is possible to recognize evidence of surface faulting from the ad 60 earthquake at colossae we can reconstruct the local geomorphic evolution and show its relationship to the ad 60 earthquake in particular cases deciphering local folk tales legends and myths may provide useful data on the historical seismicity of an area this subject has only recently been investigated by geologists bentor 1989 guidoboni 1989 armijo et al 1991 nur 1991 piccardi 2000 2005 but is still complicated because it deals with documents derived from oral tradition many of these documents are based on a codified religious terminology which sounds unfamiliar today and contributes to the lack of precision in specific cases where geological phenomena are clearly quoted geological analysis can be used as an interpretative key of legends this study presents a case history where legendary narrations from the denizli basin aegean turkey fig 1a provide useful geological and palaeoseismological information in particular traditions related to a famous earthquake that occurred in ad 60 and two famous ancient sanctuaries of this area colossae located at the southern margin of the basin and hierapolis about 15 km to the nw are examined fig 1b early christian and medieval legends based on geological events are attached to these two places the apparition of archangel michael at colossae and the apocryphal account of the arrival of st philip at hierapolis both legends were later commemorated by famous sanctuaries that have attracted pilgrims through the centuries moreover at hierapolis the geological basis for these legends constituted the source event for local religious rituals also at an earlier level in the greek roman sanctuary of apollo only sparse descriptions about the effects of the ad 60 earthquake are available in historical documents thus oral tradition is the only source of further information the natural phenomena that led to these legends are coseismic geomorphic effects related to that strong earthquake for which legend is the only existent testimony the cases illustrated here are clear examples of how particular hagiographic legends can constitute quasi historical documents following a tectonic study of the area and review of historical accounts this paper focuses on two main aspects of local myths and geology the first recovers important information to reconstruct the seismotectonic parameters of the ad 60 earthquake in particular identifying its source as being the master fault of the denizli basin and the second gains insight into the true origin of particular legends and the reasons for sacred site selection in addition this multidisciplinary approach sheds light on important developments in the evolution of western religious thought

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

geochemistry of low molecular weight hydrocarbons in hydrothermal fluids from middle valley northern juan de fuca ridge abstract hydrothermal vent fluids from middle valley a sediment covered vent field located on the northern juan de fuca ridge were sampled in july 2000 eight different vents with exit temperatures of 186 281 c were sampled from two areas of venting the dead dog and odp mound fields fluids from the dead dog field are characterized by higher concentrations of nh3 and organic compounds c1 c4 alkanes ethene propene benzene and toluene compared with fluids from the odp mound field the odp mound fluids however are characterized by higher c1 c2 c3 and benzene toluene ratios than those from the dead dog field the aqueous organic compounds in these fluids have been derived from both bacterial processes methanogenesis in low temperature regions during recharge as well as from thermogenic processes in higher temperature portions of the subsurface reaction zone as the sediments undergo hydrothermal alteration carbon dioxide and hydrocarbons are released to solution as organic matter degrades via a stepwise oxidation process compositional and isotopic differences in the aqueous hydrocarbons indicate that maximum subsurface temperatures at the odp mound are greater than those at the dead dog field maximum subsurface temperatures were calculated assuming that thermodynamic equilibrium is attained between alkenes and alkanes benzene and toluene and carbon dioxide and methane the calculated temperatures for alkene alkane equilibrium are consistent with differences in the dissolved cl concentrations in fluids from the two fields and confirm that subsurface temperatures at the odp mound are hotter than those at the dead dog field temperatures calculated assuming benzene toluene equilibrium and carbon dioxide methane equilibrium are similar to observed exit temperatures and do not record the hottest subsurface conditions the difference in subsurface temperatures estimated using organic geochemical thermometers reflects subsurface cooling processes via mixing of a hot low salinity vapor with a cooler seawater salinity fluid because of the disparate temperature dependence of alkene alkane and benzene toluene equilibria the mixed fluid records both the high and low temperature equilibrium conditions these calculations indicate that vapor rich fluids are presently being formed in the crust beneath the odp mound yet do not reach the surface due to mixing with the lower temperature fluids

convective hydrothermal c02 emission from high heat flow regions abstract in addition to volatiles released from volcanoes the flux of co2 to the atmosphere from other sources e g metamorphism and subsurface magmatism represents an important aspect of the global carbon cycle we have obtained a direct estimate of the present day atmospheric co2 flux from convective hydrothermal systems within subaerial seismically active high heat flow regions geothermal systems of the salton trough california u s a and the taupo volcanic zone new zealand provide benchmarks for quantifying convective hydrothermal co2 fluxes from such regions co2 fluxes from the salton trough 109 mol yr 1 and the taupo volcanic zone 8 109 mol yr 1 were computed using data on convective heat flow and the temperatures and co2 concentrations of reservoir fluids the similarity in specific co2 flux 106 mol km 2 yr 1 from these two disparate geologic tectonic settings implies that this flux may be used as a baseline to compute convective hydrothermal co2 emission from other areas of high heat flow if this specific flux is integrated over high heat flow areas of the circum pacific and tethyan belts the total global co2 flux could equal or exceed 1012 mol yr 1 adding this flux to a present day volcanic co2 flux of 4 1012 mol yr 1 the total present day earth degassing flux could balance the amount of co2 consumed by chemical weathering 7 1012 mol yr 1

an experimental study of grain scale melt segregation mechanisms in two common crustal rock types creation of pathways for melt to migrate from its source is the necessary first step for transport of magma to the upper crust to test the role of different dehydration melting reactions in the development of permeability during partial melting and deformation in the crust we experimentally deformed two common crustal rock types a muscovite biotite metapelite and a biotite gneiss were deformed at conditions below at and above their fluid absent solidus for the metapelite temperatures ranged between 650 and 800 c at pc 700 mpa to investigate the muscovite dehydration melting reaction for the biotite gneiss temperatures ranged between 850 and 950 c at pc 1000 mpa to explore biotite dehydration melting under lower crustal conditions deformation for both sets of experiments was performed at the same strain rate e 1 37 10 5 s 1 in the presence of deformation the positive v and associated high dilational strain of the muscovite dehydration melting reaction produces an increase in melt pore pressure with partial melting of the metapelite in contrast the biotite dehydration melting reaction is not associated with a large dilational strain and during deformation and partial melting of the biotite gneiss melt pore pressure builds more gradually due to the different rates in pore pressure increase melt enhanced deformation microstructures reflect the different dehydration melting reactions themselves permeability development in the two rocks differs because grain boundaries control melt distribution to a greater extent in the gneiss muscovite dehydration melting may develop melt pathways at low melt fractions due to a larger volume of melt in comparison with biotite dehydration melting generated at the solidus this may be a viable physical mechanism in which rapid melt segregation from a metapelitic source rock can occur alternatively the results from the gneiss experiments suggest continual draining of biotite derived magma from the lower crust with melt migration paths controlled by structural anisotropies in the protolith

geochemistry of carbon dioxide in six travertine depositing waters of italy abstract the chemical compositions of six travertine depositing hot spring waters in italy are described with emphasis on the carbon dioxide system all springs contained high concentrations of co 2 20 mm l 1 with equilibrium partial pressures well above those which could have been formed in contact with a soil atmosphere after surfacing the co 2 is rapidly lost to the atmosphere with evasion rates close to the springs ranging from 0 45 4 41 mm m 2 s 1 partial pressures of c02 showed an exponential decline with distance which is consistent with the static film model where temperature and turbulence are constant downstream co 2 transfer coefficients which ranged from 66 to 360 cm h 1 were consistent with moderately turbulent flow however there was no correlation between turbulence measured as the mean shear stress and co 2 evasion rate the channels investigated had all been modified by man and most possessed even widths and gradients all waters became increasingly supersaturated with aragonite and calcite downstream and both of these minerals were present in fresh travertine deposits the supersaturation was driven almost exclusively by gas evasion comparison of daytime and nighttime evasion rates demonstrated that photosynthetic activity was an insignificant source of co 2 flux in the reaches investigated carbon dioxide evasion is therefore primarily responsible for the supersaturation and probably also the deposition of travertine at these sites the caco 3 content of the travertines ranged from 91 3 to 96 0 wt with 1 7 4 1 caso 4 traces of organic matter and acid insoluble minerals

the inception and growth of leucosomes microstructure at the start of melt segregation in migmatites the beginning stages of melt segregation and the formation of leucosomes are rarely preserved in migmatites most arrays of leucosomes record a more advanced stage where flow dominates over segregation however the early stages in the formation of leucosomes and the segregation of melt are preserved in a partially melted meta argillite from the metatexite zone 800 c of the contact aureole around the duluth complex minnesota the rock contains 2 4 modal leucosome in a matrix consisting of 40 5 in situ neosome and 57 1 cordierite plagioclase framework the domainal microstructure in the matrix is a pre anatectic feature resulting from the bulk composition terminal chlorite reactions produced a large volume of cordierite which with plagioclase formed a framework that enclosed patches of biotite quartz plagioclase k feldspar upon melting these fertile domains became patches of in situ neosome plagioclase in the neosome is less sodic than in the leucosome hence segregation of melt occurred during crystallization not melting segregation was delayed because the cordierite plagioclase framework was strong enough to resist dilatation and compaction until after crystallization started the leucosomes are small i e they are microleucosomes and display a systematic progression in morphology as length and aspect ratio increase from 1 to 19 mm and from 2 5 to 30 respectively small equant micropores form first and in places these coalesce into small 1 mm aspect ratio 2 5 isolated blunt ended elliptical microleucosomes in the next stage micropores develop ahead of and at 45 to the left and right of the blunt tip of a microleucosome one of these develops into an elliptical leucosome and an en echelon array of either a left or right stepping elliptical microleucosome forms each elliptical microleucosome in the en echelon arrays is separated by a bridge of matrix next microleucosomes of greater length 4 mm and aspect ratio 5 form when the bridges of cordierite plagioclase matrix rupture and the elliptical microleucosomes link together to form a zigzag shaped microleucosome finally still longer microleucosomes with greater aspect ratios 30 are formed by the joining of zigzag arrays such a progression is characteristic of the way ductile fractures grow the segregation of melt was driven by the pressure gradient between the dilatant fracture and an adjacent in situ neosome which drew melt to the growing fracture thereby creating a microleucosome the microleucosomes are filled arrays of ductile fractures melt was contiguous only between microleucosomes and adjacent patches of in situ neosome the length scale of segregation was 5 mm the size of a typical patch of in situ neosome and restricted by the surrounding impermeable cordierite plagioclase framework the melt in the microleucosome was the most fractionated and the last to crystallize all microleucosomes contain entrained minerals as a consequence of their mechanism of growth rupture of the bridges resulted in the entrainment of pre anatectic phases however microleucosomes that cross patches of in situ neosome are also contaminated with peritectic phases that were transported with the melt

on the rheologically critical melt fraction abstract with increasing melt fraction the strength of partially molten granite decreases from a value characteristic of solid competent rock to a value nearly equal to that of the melt previously published mechanical and microstructural data indicate that deformation in partially molten rocks often involves brittle processes thus the pressure in the melt is expected to be important in determining strength when the volume changes during deformation strength and fluid flow will be coupled by such parameters as permeability k storage capacity per unit volume or storativity s melt compressibility f grain size d fluid viscosity and strain rate experiments on brittle rock at low temperatures show that the strain rate at which the internal fluid pressure can be maintained constant is approximately proportional to k s an evaluation of published experimental data suggests that this relation also holds for partially molten granites indicating that the strength of these rocks depends on their transport properties since the permeability is related to below a critical melt fraction rcmf the melt pressure will change if deformation is not iso volumetric by assuming a power law relationship between k and we estimate that rcmf f d m 1 n 1 where m and n relate permeability to grain size and respectively

behaviour of major elements and some trace elements li rb cs sr fe mn w f in deep hot waters from granitic areas abstract analyses of selected hot springs in more than sixty areas in granites from europe are presented concentrations of major elements and of some trace elements li rb cs sr fe mn w f in high ph waters are not significantly affected by processes during uprise from the deep reservoir to the surface re equilibrations mixing with surficial waters normalized to k or na concentrations of all other elements are related to the aquifer temperature the knowledge of aquifer temperature and total electric charge of mobile elements cl s possibly f allows us to predict both major elements within 50 and trace elements within a factor 2 or 3 concentrations in alkaline waters from granites

rare earth elements yttrium and pb isotope ratios in thermal spring and well waters of west anatolia turkey a hydrochemical study of their origin abstract rare earth elements ree yttrium major elements and pb isotope ratios were determined in thermal well and spring waters and rocks of the buyuk menderes and gediz grabens turkey which includes the geothermal fields of kizildere salavatli germencik kula and salihli together with the results of short and long time leaching of local rocks ree and y and pb isotope ratios indicate that the palaeozoic mica schists dominantly control the ree and y signatures of the deep seated na hco 3 waters marbles may also be involved but their low ree contribution is overridden by the much higher ree and y abundances in the mica schists palaeozoic gneisses can be excluded as source rocks by both pb isotope ratios and ree leaching behaviour the deep seated waters either ascend rapidly in production wells and precipitate carbonate silica scales at temperatures of about 200 c or these waters ascend slowly to springs become enriched in ca 2 cl and so 4 2 and discharge with temperatures up to 100 c as fumaroles or hot springs some of these spring waters precipitate large amounts of travertine upon exsolution of co 2 in contrast the thermal ca hco 3 type of water from pamukkale has its source in the regional pliocene limestones

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

dating the homo erectus bearing travertine from kocabas denizli turkey at at least 1 1 ma abstract since its discovery within a travertine quarry the fragmentary cranium of the only known turkish homo erectus the kocabas hominid has led to conflicting biochronological estimations first estimated to be 500 ka old the partial skull presents a combination of archaic and evolved features that puts it as an intermediate specimen between the dmanisi fossils homo georgicus and the chinese zhoukoudian skulls homo erectus respectively dated to 1 8 to 0 8 ma here we present a multidisciplinary study combining sedimentological paleontological and paleoanthropological observations together with cosmogenic nuclide concentration and paleomagnetic measurements to provide an absolute chronological framework for the upper fossiliferous travertine unit where the kocabas hominid and fauna were discovered the 26 al 10 be burial ages determined on pebbles from conglomeratic levels framing the upper fossiliferous travertine unit which exhibits an inverse polarity constrains its deposition to before the cobb mountain sub chron that is between 1 22 and 1 5 ma the alternative match of the normal polarity recorded above the travertine with the jaramillo subchron lower limit 1 07 ma may also be marginally compatible with cosmogenic nuclides interpretation thus the proposed minimum age of 1 1 ma for the end of massive travertine deposition the actual age of the fossils is likely to be in the 1 1 1 3 ma range this absolute date is in close agreement with the paleoanthropological conclusions based on morphometric comparisons implying that kocabas hominid belongs to the homo erectus s l group that includes chinese and african fossils and is different from middle and upper pleistocene specimens furthermore this date is confirmed by the large mammal assemblage typical of the late villafranchian because it attests to the antiquity of human occupation of the anatolian peninsula and one of the waves of settlements out of africa this work challenges the current knowledge of the homo erectus dispersal over eurasia

superimposed basin formation during neogene quaternary extensional tectonics in sw anatolia turkey insights from the kinematics of the dinar fault zone abstract in the extensional province of sw anatolia the cross cutting relationship between the nw and ne oriented neogene and quaternary basins is an ongoing debate in the understanding of the tectonic evolution of this area in order to contribute to this issue we carried out a structural and kinematic study along the seismogenic nw trending dinar fault zone dfz this structure was initially controlled by the sedimentary and tectonic evolution of the ne oriented neogene baklan acigol and burdur basins and later by the nw oriented quaternary dinar basin on the basis of 1000 structural and kinematic data in conjunction with basin stratigraphy the dfz can be divided into three almost parallel and continuous bands that are a the hangingwall where quaternary sediments are deformed by normal faults with mechanical striations b the inner zone corresponding to the present dinar fault scarp where nw trending normal faults with mechanical striations are dominant and c the outer zone located in the footwall of the structure comprising the area between the fault scarp and undeformed bedrock where faults exhibit variable orientation and kinematics from strike slip to normal dip slip these kinematics are mainly indicated by calcite shear veins and superimposed mechanical striations respectively this suggests that the dfz changed kinematics over time i e the dfz initiated as dominant dextral strike slip to oblique slip fault system and continued with a dominant normal movement therefore we hypothesize that the nw trending dfz was initially a transfer zone during the late miocene pliocene coeval to the sedimentary and structural evolution of the ne trending baklan acigol and burdur basins during the quaternary the dfz representing an already weakened crustal sector played the role of a normal fault system providing the accommodation space for the quaternary dinar basin hydrothermal circulation and volcanism at ne nw trending faults intersection implies structurally driven conduits channeling fluids from depth to surface

rheological transitions and the progress of melting of crustal rocks abstract high grade igneous and metamorphic systems which possess a variable percentage of melt may undergo a transition between crystal supported and fully fluid behavior the melt fraction interval over which this transition occurs is not well constrained we have conducted six series of numerical simulations of crustal melting using melt fraction intervals between 0 05 to 0 15 for this mechanical transition the results of these simulations demonstrate the dependence of convection and progress of melting on the rheological transition between solid and melt convective heat flux varied by a factor of 8 over the duration of the simulations 160 yr and the mass of melt produced varied by nearly a factor of 4 the onset of convection in simulations with the most gradual rheological transition was suppressed convective heat flux and progress of melting were more sensitive to the melt fraction interval for the rheological transition than to the composition of a range of crustal protoliths the rheological transition between solid and melt may be one of the dominant factors controlling the thermal evolution of high grade crustal rocks

some comments on the rheologically critical melt percentage abstract the concept of rheologically critical melt percentage rcmp originally proposed by arzi tectonophysics 44 1978 173 184 for partially molten granitic rocks is re examined it is shown that there is no experimental support to show the presence of rcmp the published experimental data suggest that the effective viscosity of partially molten granitic rocks is reduced rapidly and continuously with increasing melt fraction it is also shown that the experimental data may be modeled by means of the upper bound behavior the voigt bound of two phase material by assuming a melt localization which implies that there is no partitioning of strain between the solid and the melt

tracing deep thermal water circulation systems in the e w trending buyuk menderes graben western turkey abstract we present information on the spatial variation of helium isotope ratios and several conservative geochemical constituents that serve as natural tracers to identify thermal water flow systems along the e w trending buyuk menderes graben the air normalized r r a ratios where r sample 3 he 4 he and r a air 3 he 4 he of geothermal fluids in the graben range from 3 69 to 0 2 r r a ratios of the high temperature fluids display regular variation along the graben from high mantle values in the east to low crustal values in the west the highest r r a ratios showing significant mantle he signatures occur at the eastern segment of the graben in the central section r r a ratios are lower and vary between 1 82 and 1 14 the lowest ratio of 0 20 r a indicating a value of high crustal helium up to 98 was observed in the germencik field where one of the highest temperatures recorded was 232 c at the western segment of the graben a regional variation is also apparent in the co 2 he systematics mantle derived carbon proportions were found to be generally less than 2 but similar to the r r a ratios the higher mantle carbon proportions occur at the eastern segment of the graben the spatial distribution of all the data points over the entire extent of the graben shows a regularly decreasing trend of mantle derived he and co 2 contributions toward the west these results were interpreted as a progressive dilution process of mantle volatiles resulting from the systematic addition of 3 he depleted crustal co 2 components finally because the r r a ratios of geothermal fluids in the graben decrease continuously in e to w direction we propose a continuous dilution process involving the addition of crustal radiogenic 4 he associated with deep circulating fluid flow this conclusion is compatible with the b and cl concentrations of the thermal waters that show a westward increasing trend this trend appears to be controlled by water rock interaction and may be linked to a possible thermal water circulation system trending from e to w toward the aegean sea

melt segregation and matrix compaction the mush continuity equation compaction segregation time implications summary two phase aggregates a special case of which is partially molten systems are commonly modelled as an interpenetrating flow of two viscous liquids and are therefore described in terms of the fluid mechanics the governing equation set of fluid mechanics describing a two phase aggregate is incomplete as it consists of nine equations momentum and mass conservation equations for each phase and an energy conservation equation in ten unknowns six velocity components two pressures temperature and melt fraction in this paper the general equation closing the governing equation set is derived it explicitly expresses the condition of the coupling between the liquid percolation and porosity volume change due to which the medium continuity is maintained therefore the equation may be referred to as the mush continuity equation the character of the closed set solutions is demonstrated using 1 d isothermal models by examples of melt segregation inside a bounded low melting degree zone and sediment compaction at the bottom of a reservoir the compaction segregation style and time are controlled by the compaction segregation parameter c l c 2 and compaction segregation length depending on the mushy layer thickness l matrix permeability k characteristic porosity 0 and matrix and fluid viscosities at low c which approximately corresponds to low viscosity liquids kimberlites carbonatites the compaction segregation time scales as l 1 which effectively constrains the molten region thickness at the moment of the segregation and appears to explain the small volume and clustering of low viscosity magma eruptions characteristic of kimberlites at high c the porosity evolves through a formation of a series of isolated waves which could provide an explanation for the rhythmicity observed in large layered plutons

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

global positioning system constraints on plate kinematics and dynamics in the eastern mediterranean and caucasus we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1997 at 189 sites extending east west from the caucasus mountains to the adriatic sea and north south from the southern edge of the eurasian plate to the northern edge of the african plate sites on the northern arabian platform move 18 2 mm yr at n25 5 w relative to eurasia less than the nuvel 1a circuit closure rate 25 1 mm yr at n21 7 w preliminary motion estimates 1994 1997 for stations located in egypt on the northeastern part of africa show northward motion at 5 6 2 mm yr also slower than nuvel ia estimates 10 1 mm yr at n2 4 e eastern turkey is characterized by distributed deformation while central turkey is characterized by coherent plate motion internal deformation of 2 mm yr involving westward displacement and counterclockwise rotation of the anatolian plate the anatolian plate is de coupled from eurasia along the right lateral strike slip north anatolian fault naf we derive a best fitting euler vector for anatolia eurasia motion of 30 7 0 8 n 32 6 0 4 e 1 2 0 1 myr the euler vector gives an upper bound for naf slip rate of 24 1 mm yr we determine a preliminary gps arabia anatolia euler vector of 32 9 1 2 n 40 3 1 1 e 0 8 0 2 myr and an upper bound on left lateral slip on the east anatolian fault eaf of 9 1 mm yr the central and southern aegean is characterized by coherent motion internal deformation of 2 mm yr toward the sw at 30 1 mm yr relative to eurasia stations in the se aegean deviate significantly from the overall motion of the southern aegean showing increasing velocities toward the trench and reaching 10 1 mm yr relative to the southern aegean as a whole

regional heat flow in western anatolia using silica temperature estimates from thermal springs regional trends of variation of heat flow in western anatolia have been outlined using the silica temperature estimator on thermal springs silica heat flow values from 187 springs have been calculated the data are corrected for local long term mean annual surface temperature a mean value of heat flow for the western part of anatolia of 107 45 mw m 2 has been obtained which is about 60 above the world average the silica heat flow data are compared with available conventional heat flow values for this region a general agreement is observed and new patterns are recognized a close association exists between areas of high silica heat flow values above 100 mw m 2 and areas of tertiary and younger volcanism high heat flow is also observed in palaeozoic units of the menderes massif which is under tensional stress the highest heat flow estimate of 247 mw m 2 is obtained near gediz 38 57 n 29 13 2 e this area is part of a seismically active region and is located near a middle eocene subduction zone which is an area of later collision tectonics the new heat flow data from western anatolia improve our knowledge of the thermal conditions within the crust this information is important for the analysis of various geophysical and geological phenomena including seismicity

flow of synthetic wet partially molten granite under undrained conditions an experimental study 1 major problems in experimental studies of the flow of partially molten granitic rocks are 1 maintaining control of the grain size of the matrix of solid grains 2 controlling the melt fraction and 3 controlling the melt viscosity closely linked to water content to overcome these problems we used a synthetic granitoid comprising a solid matrix of quartz grains 50 m grain size mixed with an albite quartz melt prepared from oxides with added water 2 5 wt dissolved in the melt phase viscosity 9 104 pa s experiments were performed undrained with melt fractions of 0 1 0 2 0 25 and 0 3 constant strain rate creep and stress relaxation experiments were carried out in a gas medium apparatus at 1273 and 1173 k mostly at 300 mpa confining pressure up to 15 shortening strain strain rates ranged between 10 4 to less than 10 7 s 1 and fully ductile mechanical behavior was observed melt fraction has a more profound effect on strength than water content temperature or total confining pressure low strain rate 10 6 s 1 data were fitted to an empirical flow law of the form d dt a exp b m exp h rt n with the parameters loga 1 39 m 3 n 1 8 b 192 h 220 kjmol 1 where d dt is strain rate s 1 is flow stress mpa is melt fraction and t is temperature k strength is expected to fall rapidly above about 0 4 melt fraction to levels characteristic of flow of the melt containing suspended crystallites extrapolation to geological strain rates using this flow law shows that in nature migmatites bearing granitic melt will be extremely weak much weaker than silicate rocks deforming by intracrystalline plasticity microstructural study shows grains remain equant at all strains with no discernable formation of a grain flattening fabric nor a large strain contribution from microfracturing thus bulk intracrystalline plasticity is of minor importance and intergranular sliding is implied the nonlinear flow observed is tentatively attributed to a combination of sintering of grain contacts and sliding failure of such contacts with a substantial contribution from diffusive transfer processes

fluxes of deep co2 in the volcanic areas of central southern italy abstract both the shallow organic derived and deep mantellic magmatic metamorphic fluxes of co 2 co 2 mass time 1 and specific fluxes of co 2 co 2 mass time 1 surface 1 dissolving in the shallow groundwaters of the volcanic areas of amiata vulsini vico sabatini albani roccamonfina vesuvio vulture and etna were evaluated by partitioning the composed population of total dissolved inorganic carbon in two individual populations and subsequent subtraction of local background population the flux of deep co 2 released from the geothermal fields of piancastagnaio amiata torre alfina latera marta bracciano south cesano and mofete and from the overall northern latium hydrothermal reservoir were also evaluated by means of the total surface heat flux and the enthalpy and co 2 molality of the single liquid phase circulating in each geothermal reservoir these data suggest that the co 2 released to the atmosphere varies from 9 5 10 6 to 3 0 10 6 mol year 1 km 2 over the geothermal fields of bracciano south and cesano respectively and that a total co 2 of 3 8 10 8 mol year 1 is cumulatively released from the geothermal fields of torre alfina latera and cesano extending over an area of only 66 km 2 in addition a flux of 2 2 10 11 to 3 8 10 11 mol year 1 of gaseous co 2 entering the atmosphere is obtained for the entire anomalous area of central italy extending from the tyrrhenian coastline to the apennine chain 45 000 km 2 thus terrestrial co 2 emission in central southern italy appears to be a significant carbon source

mantle flow uplift of western anatolia and the aegean interpretations from geophysical analyses and geodynamic modeling 1 the western anatolian and aegean region demonstrates a complex geologic history of horizontal and vertical tectonics active normal faulting and exhumation zones indicate that western anatolia has experienced significant extension since the oligocene early miocene 30 ma our geophysical analyses demonstrate that the region is also uplifted relative to an elevation that would be expected given an isostatic response to the lithosphere structure namely topography residuals indicate a residual uplift of about 1500 m over 200 km sections of western anatolia and the aegean admittance functions between free air gravity and topography indicate that the regional topography is isostatically uncompensated and as it approaches 50 mgal km at the longest wavelengths the uncompensated topography is likely owing to an underlying mantle flow component using forward geodynamic modelling we consider an idealized section of western anatolian lithosphere based on tomographic inversions and examine the magnitude and pattern of surface topography to reconcile with the geophysical observables the models consistently show a plateau type uplift and horizontal extension through western anatolia with an amplitude and wavelength consistent with the residual topography calculations together the geophysical analyses and modelling provide independent quantitative evidence that the thin anatolian aegean lithosphere is being buoyed upwards by underlying mantle flow the mantle flow may be associated with active lithosphere delamination beneath the region a process that would also explain the ongoing crustal extension

experimental deformation of partially melted granitic aggregates abstract the effects of varying amounts of partial melt on the deformation of granitic aggregates have been tested experimentally at conditions 900 c 1500 mpa 10 4 to 10 6 s where melt free samples deform by dislocation creep with microstructures approximately equivalent to those of upper greenschist facies experiments were performed on samples of various grain sizes including an aplite 150 m and sintered aggregates of quartz albitemicrocline 10 50 and 2 10 m water was added to the samples to obtain various amounts of melt 1 15 in the aplite 1 5 in the sintered aggregates optical and tem observations of the melt distribution in hydrostatically annealed samples show that the melt in the sintered aggregates is homogeneously distributed along an interconnected network of triple junction channels while the melt in the aplites is inhomogeneously distributed the effect of partial melt on deformation depends an melt amount and distribution grain size and strain rate for samples deformed with 1 melt all grain sizes exhibit microstructures indicative of dislocation creep for samples deformed with 3 5 melt the 150 m and 10 50 m grain size samples also exhibit dislocation creep microstructures but the 2 10 m grain size samples exhibit abundant tem scale evidence of dissolution precipitation and little evidence of dislocation activity suggesting a switch in deformation mechanism to predominantly melt enhanced diffusion creep at natural strain rates melt enhanced diffusion creep would predominate at larger grain sizes although probably not for most coarse grained granites the effects of melt percentage and strain rate have been studied for the 150 m aplites for samples with 5 and 10 melt deformation at 10 6 s squeezes excess melt out of the central compressed region allowing predominantly dislocation creep conversely deformation at 10 5 s produces considerable cataclasis presumably because the excess melt cannot flow laterally fast enough and a high pore fluid pressure results for samples with 15 melt deformation at both strain rates produces cataclasis presumably because the inhomogeneous melt distribution resulted in regions of decoupled grains which would produce high stress concentrations at point contacts at natural strain rates there should be little or no cataclasis if an equilibrium melt texture exists and if the melt can flow as fast as the imposed strain rate however if the melt is confined and cannot migrate a high pore fluid pressure should promote brittle deformation

paleoatmospheric consequences of co2 released during early cenozoic regional metamorphism in the tethyan orogen the eocene was the warmest epoch of the cenozoic with published estimates of eocene atmospheric co2 content ranging from two to six times the current value calculations of co2 consumption by silicate weathering show that co2 fluxes to the atmosphere of ca 1018 myr could account for inferred paleocene eocene atmospheric co2 contents and the resulting greenhouse effect would have contributed to eocene warmth extensive portions of the tethyan orogen underwent regional metamorphism culminating in the eocene prograde metamorphism may have been contemporaneous with the late paleocene global warming we calculated the amount of metamorphic co2 produced at depth in the himalayan orogen with data on the timing of the india asia collison duration of prograde regional metamorphism and proportions and bulk compositions of metamorphic co2 source rocks if co2 was generated at a constant rate over a 10 myr period of prograde metamorphism in the himalayan orogen we estimate that ca 1018 1019 moles myr of metamorphic co2 were produced at depth significant expulsion of metamorphic co2 to the atmosphere may have occurred by focused fluid flow along shear zones such as the extensive main central thrust in the himalayan orogen an additional ca 1018 myr could have been contributed by eocene regional metamorphism in the mediterranean tethys i e from the alps to turkey the extensive metamorphism associated with the india asia collision and the closing of tethys may have contributed to co2 greenhouse warming in the early to mid cenozoic

gypsiferous carbonates at honaz dagi denizli first documentation of triassic gypsum in western turkey and its tectonic significance abstract this paper is the first to document the presence of triassic evaporites from the anatolide toride carbonate platform by providing stratigraphic structural mineralogic petrographic and isotopic analyses we have performed isotopic analyses on selected gypsum samples with 34s values vary between 15 1 and 18 1 and 87sr 86sr ranges between 0 707761 and 0 707772 the new isotopic data is very similar to late triassic gypsum of the mediterranean belt and therefore the age of the gypsum bearing formation is assigned as late triassic we have carried out a detailed study in the area of honaz dagi 20 km east of denizli sw turkey and its close vicinity here gypsum bearing rocks are well exposed allowing us to establish the stratigraphic and tectonic position of the sequence the gypsiferous carbonate sequence occurs as a tectonic slice with no observed stratigraphic contacts it is structurally overlain by a mesozoic early tertiary turbiditic olistostromal unit late triassic liassic dolomitic limestone and cretaceous ophiolite the gypsiferous sequence is characterized by intercalation of white grey massive gypsum and black dolomitic limestone the gypsum at the outcrops seems to be secondary formed by the hydration of precursor anhydrite and shows typical porphyroblastic and alabastrine textures with corroded anhydrite relics the deformation affecting the late triassic gypsum bearing sequence has been grouped under two major phases first thrusting with intense folding and imbrication showing compressional deformation with top to the ne sense of shear this deformation is widespread in the kalebogazi formation and the structurally overlying dolomitic gereme formation second the formation of e w trending high angle normal faults and n trending strike slip faults which control the present day structural frame of the region

kinematic development and paleostress analysis of the denizli basin western turkey implications of spatial variation of relative paleostress magnitudes and orientations paleostress orientations and relative paleostress magnitudes stress ratios determined by using the reduced stress concept are used to improve the understanding of the kinematic characteristics of the denizli basin two different dominant extension directions were determined using fault slip data and travertine fissure orientations in addition to their stratigraphically coeval occurrence the almost exact fit of the s2 and s3 orientations for the ne sw and nw se extension directions in the late miocene to recent units indicate that these two extension directions are a manifestation of stress permutations in the region and are contemporaneous this relationship is also demonstrated by the presence of actively developing ne sw and nw se elongated grabens developed as the result of ne sw and nw se directed extension in the region moreover stress ratios plots indicate the presence of a zone of major stress ratio changes that are attributed to the interference of graben systems in the region it is concluded that the plotting of stress orientations and distribution of stress ratios is a useful tool for detecting major differences in stress magnitudes over an area the boundaries of which may indicate important subsurface structures that cannot be observed on the surface q 2005 elsevier ltd all rights reserved

the velay dome french massif central melt generation and granite emplacement during orogenic evolution this paper is a synthesis of available data on the velay dome that include both small and large scale lithologic and structural mapping strain analysis isotope geochemistry geochronology and pressure temperature estimates the velay dome one of the largest granite migmatite domes of the variscan belt formed during orogenic collapse at around 300 ma its study allows an assessment of the thermal and geodynamic context leading to voluminous crustal anatexis of the variscan orogenic crust a first melting stage developed in connection with south verging thrust zones during the early carboniferous leading to a crustal thickening estimated at 20 km minimum the involvement of fertile lithologies and the intrusion of plutons of deep origin contributed to the development of water saturated melts the volume of biotite granite extracted from melt during this period was limited the second phase of melting corresponded to generalized melting of gneiss achieved by biotite dehydration melting reactions and accompanied by the generation of cordierite bearing granites at this stage crustal scale detachment faults were activeandpartiallyobliteratedtheearlierstructures thenewstructureswereprogressivelytiltedtotheverticalatthemarginofthe velay dome due to the southward and lateral ballooning of the granitic dome the reconstructed p t path indicate that the large volume ofmelt produced was a consequence ofa significant increase in temperature at the onset of biotite dehydration melting at the base of the crust this melting event is coeval with granulite facies metamorphism associated to underplating of mantle derived magmas as suggested by the geochemical signature of late paleozoic lower crustal xenoliths sampled by cenozoic volcanoes and withtheisotopicsignatureofthelategraniticintrusions accordingly itisproposedthatasthenosphericupwellingwasresponsible for the temperature increase favoring melting of hydrous minerals d 2001 published by elsevier science b v

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