major pathways of atlantic water in the northern north atlantic and nordic seas toward arctic 1 the major pathways of near surface atlantic water in the northern north atlantic and nordic seas are identified as current speeds above 30 cm s using 1014 lagrangian drifters combined with previously published hydrography the inflow over the scotland greenland ridge and establishment of the two branch norwegian atlantic current nwac are described in light of the circulation in the northern north atlantic the western branch of the nwac appears as a jet in the polar front topographically guided from the iceland faroe front through the nordic seas toward fram strait the eastern branch starts as a shelf edge current above the irish scottish continental shelf and after passing through the faroe shetland channel it continues northward along the norwegian shelf edge toward the arctic with a branch bifurcating into the barents sea the nwac appears to maintain its two branch structure throughout the nordic seas with the atlantic water confined to a 200 600 km wide wedge

very low grade metamorphism of sedimentary rocks of the meliata unit western carpathians slovakia implications of phyllosilicate characteristics the meliata unit represents a melange like accretionary wedge containing blueschist facies tectonic blocks and slices in a triassic and jurassic sedimentary matrix the blueschist facies rocks are tectonic remnants of the subducted parts of the meliata hallstatt branch of the tethys the phyllosilicate assemblages in very low grade metapelites represent metastable disequilibrium stages which the assemblages have reached during reaction progress therefore temperature and pressure values of low t metamorphism of the sedimentary series and the late stages of decompressional cooling of blueschist facies rocks obtained by phyllosilicate crystallinity chlorite thermometric and white k mica geobarometric methods can be regarded as semiquantitative estimates however results of chlorite white mica thermobarometry suggest that local equilibrium was approached at a microscopic scale for deciphering the age relations of prograde and retrograde events k ar isotope geochronological methods were applied the sedimentary series and related basalts of the meliata unit experienced high t anchizonal prograde regional metamorphism the temperature and pressure of which can vary between ca 280 and 350 c and ca 2 5 and 5 kbar white k mica b geobarometry suggests possible minimal pressures of ca 1 5 to 3 kbar the mylonitic retrogression of blueschist facies phyllites is characterised by 340 c and 4 kbar minimal p the low t prograde metamorphism was synchronous with the retrograde metamorphism of the blueschists the ages of these two events may be between ca 150 and 120 ma culminating most probably at around 140 145 ma thus the upper jurassic lowermost cretaceous very low grade metamorphism of the meliata unit is younger than the subduction related 160 155 ma blueschist facies event and definitely older than the cretaceous 100 90 ma metamorphism of the footwall gemer palaeozoic

eddy formation near the west coast of greenland abstract this paper extends a bracco and j pedlosky s investigation of the eddy formation mechanism in the eastern labrador sea by including a more realistic depiction of the boundary current the quasigeostrophic model consists of a meridional coastally trapped current with three vertical layers the current configuration and topographic domain are chosen to match as closely as possible the observations of the boundary current and the varying topographic slope along the west greenland coast the role played by the bottom intensified component of the boundary current on the formation of the labrador sea irminger rings is explored consistent with the earlier study a short localized bottom trapped wave is responsible for most of the perturbation energy growth however for the instability to occur in the three layer model the deepest component of the boundary current must be sufficiently strong highlighting the importance of the near bottom flow the model is able to reproduce important features o

caledonian strike slip terrane accretion in w ireland insights from very low grade metamorphism illite chlorite crystallinity and b0 parameter analysis of pelites with detrital white micas in the clew bay galway bay segment of the irish caledonides indicates that b0 data from whole rock and 2 m fractions generally show differences smaller than the errors of the method irrespective of 001 illite crystallinity values probably due to metamorphic recrystallization intermediate pressure metamorphism of the ordovician silurian clew bay group indicates slow subduction allowing partial thermal re equilibration before exhumation in contrast the croagh patrick group laurentian shelf sediments underwent high pressure alteration suggesting rapid subduction exhumation synchronous with strike slip faulting the murrisk group which underwent high intermediate pressure metamorphism in an ordovician back arc forms a separate terrane to the croagh patrick group to the north and also to the ordovician lough nafooey and tourmakeady groups and rosroe formation in the south in which low intermediate pressure alteration occurred these together with the silurian north galway group may have undergone heating due to movement over or deposition on the hot gowlaun detachment as the connemara dalradian was exhumed the south connemara group also underwent a high pressure alteration consistent with its inferred subduction environment evidence of contact alteration due to known or inferred buried late to post caledonian granitoid plutons has been found in the clew bay louisburg clare island croagh patrick murrisk and south connemara groups these show evidence of lower pressure alteration than the surrounding country rocks

evolution of 2 1 layered silicates in low grade metamorphosed liassic shales of central switzerland white mica from the liassic black shales and slates in central switzerland was analysed by transmission electron microscopy tem and electron microprobe to determine its textural and compositional evolution during very low grade prograde metamorphism samples were studied from the diagenetic zone anchizone and epizone t 100 450 c phyllosilicate minerals analysed include illite smectite i s phengite muscovite brammallite paragonite margarite and glauconite textural evolution primarily is towards larger more defect free grains with compositions that approach those of their respective end members the smectite to illite transformation reduced the amounts of the exchange components sik 1al 1 mgsial 2 and fe3 al 1 these trends continue to a lesser degree in the anchizone and epizone correlations between the proportion of smectite in i s and the composition of i s indicate that smectite layers may contain a high layer charge illite in i s bears a compositional resemblance to macrocrystalline phengite in some samples but is different in others paragonite first appears in the upper diagenetic zone or lower anchizone as an interlayer deficient brammallite and it may be mixed with muscovite on the nanometre scale owing to the small calculated structure factor for paragonite muscovite superstructures conventional x ray powder diffraction cannot distinguish between mixed layer structures and a homogeneous compositionally intermediate solid solutions however indirect tem evidence shows that irregularly shaped domains of na and k rich mica exist below 10 nm subsequent coarsening of domains at higher grades produced discrete paragonite grains at the margins of muscovite crystals or in laths parallel to the basal plane of the host muscovite margarite appears in the epizone and follows a textural evolution similar to paragonite in that mixtures of margarite paragonite and muscovite may initially occur on the nanometre scale however no evidence of interlayer poor margarite has been found

a multi system geochronology in the ad 3 borehole pannonian basin hungary with implications for dating volcanic rocks by low temperature thermochronology and for interpretation of u th he data independent geochronological and thermal modelling approaches are applied to a biostratigraphically exceptionally well controlled borehole alcs ad 3 in order to constrain the age of cenozoic geodynamic events in the western pannonian basin and to test the efficacy of the methods for dating volcanic rocks apatite fission track and zircon u pb data show two volcanic phases of middle eocene 43 4 39 0 ma and early oligocene 32 72 0 15 ma age respectively apatite u th he ages 23 8 14 8 ma and independent thermal and subsidence history models reveal a brief period of heating to 55 70 ca t 17 ma caused by an increased heat flow related to crustal thinning and mantle upwelling our results demonstrate that contrary to common perception the apatite u th he method is likely to record apparent or mixed ages resulting from subsequent thermal events rather than cooling or eruption ages directly related to distinct geological events it follows that a direct conversion of apparent or mixed u th he ages into cooling exhumation or erosion rates is incorrect

systematics of chlorite alteration at the phelps dodge massive sulfide deposit matagami quebec hydrothermal alteration at the phelps dodge archcan volcanogenic massive sulfide deposit has converted rhyodacite and rhyolite footwall rocks into the following mineral assemblages quartz chlorite albite epidote or sericite quartz chlorite or sericite chlorite or sericite and chlorite talc or stilpnomelane alteration at constant al was initiated by hydration addition of fe mg silicification and leaching of ca na which produced al saturated chlorites with a wide range of fe fe mg ratios within the assemblage quartz chlorite albite epidote or sericite with continued addition of fe and less mg combined with extensive leaching of quartz the chlorite became al undersaturated quartz chlorite talc assemblage and ultimately formed a rock composed essentially of chlorite the chlorite talc or stilpnomelane assemblage is stable in late crosscutting veinlets and in the ore zone chlorites in the si al mg fe system form a rectangular solid solution plane with limited substitution of al for si and extensive substitution of fe for mg in si al space the solid solution plane is outlined by al saturation presence of other al rich mineral and al undersaturation presence of al poor or al free mineral boundaries al iv substitution for si in the chlorites increases from 2 3 to 3 01 formula units based on 8 si al iv with fe fe mg whereas al iv occupancy decreases from 2 88 to 2 65 the valence charge balance is compensated by octahedral site vacancies or by the conversion of fe super 2 to fe super 3 the al iv content of chlorite also increases with temperature chlorites on the al saturated boundary of the solid solution field form a potentially useful geothermometer t degrees c 106 al iv 18 al iv is corrected for changes with the fe fe mg ratio as al iv corrected al iv 0 7 fe fe mg the fe fe mg ratios of bulk rock and contained chlorite correlate well birefringence colors of the chlorite change from green to brown violet and berlin blue as fe fe mg changes from 0 18 to 0 64 the fe fe mg variation apparently depends largely on the proportions of mg rich seawater and fe rich hydrothermal fluid in the altering brine

lower crustal granulite xenoliths from the pannonian basin hungary part 2 sr nd pb hf and o isotope evidence for formation of continental lower crust by tectonic emplacement of oceanic crust mafic granulite xenoliths from the lower crust of the pannonian basin are dominated by lree depleted bulk rock compositions many of these have morb like 143nd 144nd but 87sr 86sr is elevated relative to most morbs their 18o values cover a wide range from 3 8 to 9 5 a group of lree enriched mafic granulites have higher 87sr 86sr 0 704 0 708 and lower 143nd 144nd 0 5128 0 5124 with higher 18o values on average 7 8 to 10 6 than the lree depleted granulites the lree enriched granulites are however isotopically similar to newly discovered metasedimentary granulite xenoliths a sublinear correlation in ehf end isotope space has a shallower slope than the crust mantle array with the metasedimentary rocks forming the low ehf end member the radiogenic end is restricted to the lree depleted granulites and these overlap the field of morb pb isotopes for the lree depleted samples are less radiogenic on average than those of the lree enriched and metasedimentary xenoliths and metasedimentary granulites have consistently higher 208pb 204pb the wide range in 18o over a restricted range in nd and sr isotope values in combination with the predominance of lree depleted trace element compositions is consistent with an origin as a package of hydrothermally altered oceanic crust the existence of 18o values lower than average morb and or mantle peridotite requires that at least some of these rocks were hydrothermally altered at high temperature presumably in the oceanic lower crust the low 143nd 144nd of the lree enriched mafic granulites cannot be explained by simple mixing between a lree depleted melt and an enriched component represented by the recovered metasediments instead we interpret these rocks as the metamorphic equivalent of the shallowest levels of the ocean crust where pillow basalts are intimately intercalated with oceanic sediments a possible model is accretion of oceanic crustal slices during subduction and convergence followed by high grade metamorphism during the alpine orogeny

boundary current eddies and their role in the restratification of the labrador sea an idealized model is used to study the restratification of the labrador sea after deep convection with emphasis on the role of boundary current eddies shed near the west coast of greenland the boundary current eddies carry warm buoyant irminger current water into the labrador sea interior for a realistic end of winter state it is shown that these irminger current eddies are efficient in restratifying the convected water mass in the interior of the labrador sea in addition it is demonstrated that irminger current eddies can balance a significant portion of the atmospheric heat loss and thus play an important role for the watermass transformation in the labrador sea

neogene quaternary magmatism and geodynamics in the carpathian pannonian region a synthesis in the carpathian pannonian region in neogene times westward dipping subduction in a land locked basin caused collision of two lithospheric blocks alcapa and tisia with the southeastern border of the european plate calc alkaline and alkaline magmatism was closely related to subduction rollback collision and extension from the spatial distribution of the magmatic activity four segments can be defined western segment magmatism occurring on the alcapa block central segment magmatism occurring on both alcapa and the tisia blocks south eastern segment and interior segment both on the tisia block most calc alkaline magmatism in the region resulted from melting of a heterogeneous asthenospheric mantle source modified by addition of fluids and sediment assimilation and fractionation processes at shallow crustal levels occurred in most of the segments strongly masking the deeper source processes long term subduction rollback and or delamination led to contamination of the asthenosphere beneath the western segment here large volume partial melts of the contaminated mantle caused underplating and crustal anatexis leading to mixing of mantle derived calc alkaline magmas with crustal melts in the central segment calc alkaline magmas were formed by subduction and rollback followed by back arc extension and slab breakoff avariable mantle source is indicated in the back arc setting and larger amount of fluid induced metasomatism source enrichment and assimilation nearer to the trench in the interior segment evolution from typical calc alkaline magmas to adakite like ones was related to extension due to fast rotations and transtensional tectonics here calc alkaline magmas formed by decompression melting of a heterogeneous crust mantle lithosphere while adakite like melts resulted from fliud dominated melting of the lithosphere along the south eastern segment slab breakoff was responsible for the generation of typical calcalkaline magmas but in the extreme south of the segment shallow level tearing of the slab followed breakoff strike slip tectonics allowed the rise of hot asthenosphere and generation of adakite like magmas via slab melting along the torn edge of the east european plate alkalic basaltic volcanism with an oib like asthenosphere source followed the calc alkaline stage

chloritization of the hydrothermally altered bedrock at the igarape bahia gold deposit carajas brazil the igarape bahia gold deposit has developed from weathering of a near vertical hydrothermal cu au mineralization zone the unweathered bedrock composed of chlorite schists is mainly metamorphosed basalts pyroclastic and clastic sedimentary rocks and iron formation contents and fe fe mg ratios of chlorites increase from distal country rock towards the mineralization zone which can be attributed to different water rock ratios and locations in a hydrothermal system in the hydrothermal system high salinity fluids convected through basin floor rocks stripping metals from the recharge zones with precipitation in discharge zones the chlorite with lower fe fe mg ratios indicates alteration by relatively unreacted mg rich fluids occurring within recharge zones by contrast the chlorite with higher fe fe mg ratios in the mineralization zone formed from solutions rich in fe mn au cu h2s and sio2 within a discharge zone the iron formation could also be formed within the discharge zone or on the basin floor from the fe rich fluids the distal country rock with less chlorite content is a hydrothermal product at low water rock ratios whereas the proximal country rock and the host rock with more chlorite content formed at high water rock ratio conditions the al iv contents of chlorites indicate that the formation temperatures of these rocks range from 204 to 266 c with temperatures slightly increasing from distal country rock towards the mineralization zone

towards a mechanical model for the formation of the pannonian basin abstract new maps showing crustal and lithospheric thickness variations in the pannonian basin and the surrounding east alpine carpathian and dinaric mountains have been prepared on the basis of recent seismic seismologic and electromagnetic data a map presenting miocene faults of regional significance has been also constructed for the same region by using a wealth of recently available national and or more local studies it is suggested that observed crustal and lithospheric structural contrasts have been controlled primarily by neogene kinematic history of the region kinematic history is characterized by the following main patterns 1 1 indentation by adria and large scale backthrusting in the southern alps 2 2 eastward escape and extension of the eastern alps 3 3 extensional collapse in the pannonian basin area 4 4 formation of broad wrench fault systems along strike in the dinarides and southern carpathians and the western carpathians with dextral and sinistral shear respectively 5 5 compression and accretion of the external thrust and fold belt in the eastern carpathians these kinematic patterns are thought to be interrelated and all are manifestations of the late stage evolution of an overthickened orogenic wedge in order to arrive at a better understanding of the mechanism of extension which formed the pannonian basin deep crustal seismic profiles hydrocarbon exploration reflection lines and borehole data have been analyzed in the little hungarian plain this plain represents the transition zone between the alps and the pannonian lowlands and the results are illustrated by eight interpreted cross sections one result of regional importance is the clear recognition that the transdanubian central range at the southeastern flank of the little hungarian plain is composed of alpine pre senonian thrust sheets this finding marks the end of a century of debate the allochthony of the substrata of the pannonian basin can be now considered proven another result of more general interest is that these cross sections document the mode of lithospheric extension preexisting compressional detachment planes reactivate as low angle normal faults and lead to tectonic unroofing of deeply buried metamorphic terranes characterized by ductile flow along subhorizontal lineation

low temperature constraints on the alpine thermal evolution of the western carpathian basement rock complexes abstract the cretaceous to palaeogene alpine exhumation of previously buried variscan basements is recorded in the southern portion of the western carpathians in the gemeric and veporic units the meso cenozoic collisional processes resulted in basement exhumation of the tatric unit from palaeogene to neogene times according to zircon and apatite fission track data the gemeric unit an uppermost thick skinned thrust sheet cooled from depth levels of 10 up to 2 5 km temperature interval of 250 60 c about 88 64 ma ago after the collapse of overlying meliata tur a silica mesozoic accretionary prism the middle and lower thick skinned thrust sheets veporic and tatric units cooled from the depths of 10 up to 2 5 km 110 40 ma ago the process was controlled by unroofing of footwall from beneath the gemeric unit about 50 20 ma ago the internal zone of tatric unit gradually exhumed to depth of

observed sources and variability of nordic seas overflow the overflows from the nordic seas maintain the deep branch of the north atlantic circulation that is an important part of the global climate system an analysis of observed ocean temperatures and salinities between 1950 and 2005 shows that the atlantic water circulating in the nordic seas is the main source for change in the overflow waters

near surface circulation in the northern north atlantic as inferred from lagrangian drifters variability from the mesoscale to interannual 1 the near surface circulation of the nordic seas is basically cyclonic and consists of jets and recirculation cells which are tightly linked to the bottom topography variable forcing by the large scale rotation of the wind leads to a modulation in the strength of the gyres and their interconnecting jets this is seen in drifter and altimeter data currents are stronger during winter and during phases of high north atlantic oscillation index the exchanges between the north atlantic and the nordic seas do not seem to be directly affected by this variable forcing the narrow boundary currents and the intergyre jets are subject to instability causing mesoscale current fluctuations which contribute to the stirring and mixing of polar and atlantic water masses

geochronological evidence for the alpine tectono thermal evolution of the veporic unit western carpathians slovakia abstract tectono thermal evolution of the veporic unit was revealed by multiple geochronological methods including 87rb 86sr on muscovite and biotite zircon and apatite fission track and apatite u th he analysis based on the new data the following alpine tectono thermal stages can be distinguished the eo alpine cretaceous nappe stacking 135 95 ma resulted in burial of the veporic unit beneath the northward overthrusting gemeric unit and overlying jurassic meliata accretionary wedge during this process the veporic unit reached metamorphic peak of greenschist to amphibolite facies accompanied by orogen parallel flow in its lower and middle crust the subsequent evolution of this crust is associated with two distinct exhumation mechanisms related to collision with the northerly tatric fatric basement the first mechanism 90 80 ma is associated with internal subhorizontal shortening of the veporic unit reflected by large scale upright folding and heterogeneous exhumation of the veporic lower crust in the cores of crustal scale antiforms this led to juxtaposition of the higher and lower grade parts of basement all cooled down to 350 c by 80 ma the second mechanism is associated with the overthrusting of the veporic unit over the attenuated fatric crust this led to a passive en block exhumation of the veporic crust from 350 c to 60 c between 80 and 55 ma followed by erosion 55 35 ma the erosion processes resulted in formation of planation surface before the late eocene transgression after erosion and planation a new sedimentary cycle of the central carpathian palaeogene basin was deposited with the sedimentary strata thickness of 1 5 2 0 km 21 17 ma the early to middle miocene is characterised by destruction tectonic disintegration and erosion of this basin 20 13 ma and formation of the neogene vepor stratovolcano 13 ma the final shaping of the area has been linked to erosional processes of the volcanic structure since the late sarmatian with accelerated processes during the plio quaternary

timing of low temperature metamorphism and cooling of the paleozoic and mesozoic formations of the bukkium innermost western carpathians hungary k ar ages of illite muscovite and fission track ages of zircon and apatite were determined from various lithotypes of the bukkium which forms the innermost segment of the western carpathians the stratigraphic ages of these dinaric type formations cover a wide range from the late ordovician up to the late jurassic the grade of the orogenic dynamo thermal metamorphism varies from the late diagenetic zone through the anchizone up to the epizone chlorite maximally biotite isograd of the greenschist facies the k ar system of the illite muscovite in the 2 m grain size fraction approached equilibrium only in epizonal and high temperature anchizonal conditions the orogenic metamorphism culminated between the eo hellenic 160 120 ma phase connected to the beginning of the subduction in the dinarides and the austrian 100 95 ma phase characterized by compressional crustal thickening no isotope geochronological evidence was found for proving any hercynian recrystallization the stability field of fission tracks in zircon was approached using the thermal histories of the different tectonic units a temperature less than 250 c and effective heating time of 20 30 ma had only negligible effects on the tracks whereas total annealing was reached between 250 and 300 c apatite fission track ages from the paleozoic and mesozoic formations show that the uplift of the bukk mountains occurred only in the tertiary not earlier than ca 40 ma ago thermal modeling based on apatite fission track length spectra and preserved paleogene sediment thickness data proved that the late neogene burial of the recently exhumed plateau of the bukk mountains exceeded 1 km

in situ u pb zircon geochronology of neogene garnet bearing lavas from slovakia carpatho pannonian region central europe abstract zircons armored in garnet from four neogene lavas of slovakia three andesites and one dacite were dated in situ using excimer laser ablation icp ms for the andesites the 66 analytical points yield a lower intercept age of 13 3 0 1 ma mswd 1 2 which is older than the age of 12 4 0 2 ma recorded for the dacite u pb ages obtained in this study are significantly younger than the lower badenian ages k ar and fission track dating coupled with biostratigraphic correlations classically assumed for the garnet bearing lavas of the western carpathians with a minimum discrepancy of 3 ma accessorily a composite zircon with an inherited core reveals that some pan african crustal component is present at depth garnet bearing andesites and dacites potentially bear critical information about melt generation in the lower crust and possible recycling of pre existing crust into igneous rocks practically the problem is to assess the nature of the melt from which the garnet actually grew for this purpose zircon grains included into garnet may help to clarify the beginning of the magma history it seems likely that zircon was not grown from the bulk dacitic or andesitic melt but rather from a specific rhyolitic batch later mixing and consecutive change in magma chemistry explain that free zircons in the melt were almost totally dissolved whereas zircons shielded into garnets were preserved finally owing to their miocene age the zircon grains armored into garnet preclude any restitic origin for their host and definitely demonstrate the magmatic origin of garnet

zircon growth and recycling during the assembly of large composite arc plutons abstract concordant u pb zircon dates have been interpreted traditionally to date the crystallization ages of plutons because until recently analytical uncertainties have generally been large enough to encompass the anticipated duration of pluton growth advances in zircon tims analysis and geochronological studies by sims on zircon from young volcanic rocks along with evolving views of the evolution of magmatic systems makes it necessary to revaluate this interpretation assignment of unique pluton crystallization ages based on zircon dating is complicated by the propensity of zircon to survive multiple intrusive events that culminate in a large pluton distinctions must be made between true inherited zircon xenocrystic zircon derived from host rocks during magma ascent and or emplacement and multi stage growth of zircon during waxing and waning of magma reservoirs that solidify to form large plutons these complications are exemplified by recent high precision u pb zircon age dating from the cretaceous tuolumne and mt stuart batholiths which clearly show that the timeframe of pluton assembly was long 5 ma for mt stuart and 8 ma for tuolumne zircon crystals from samples from both batholiths exhibit appreciable concordant age dispersion for zircon several 10 5 yr up to 2 10 6 yr and assignment of statistically valid rock solidification ages is not possible from these data low zr in the rocks of each batholith indicates that magmas were initially strongly undersaturated in zircon when emplaced and inherited zircon is rare or absent recycling of zircon antecrysts during successive magmatic injections is the primary cause of the modest age dispersion of concordant zircon ages and is compatible with progressive growth of a large long lived crystal mush body because eruption of magma requires low to moderate crystal fraction and high temperatures relative to stored crystal mushes zircon crystals are more likely to be eradicated during thermal rejuvenation preceding major eruptions

tertiary subduction and slab break off model of the carpathian pannonian region abstract this paper illustrates the application of multidisciplinary data analysis to the carpathian pannonian region and presents a new tertiary development model that incorporates all multidisciplinary parameters during the late cretaceous eocene the future carpathian orogen was part of the larger alpine carpathian orogen formed by the southeastward subduction 135 55 ma of the penninic ocean and the ultimate collision 55 40 ma of the european and adriatic continents the subduction in the alpine region ended by the slab break off of the subducting oceanic lithosphere from the continental one and by the related magmatism 43 24 ma while the eocene alps were under continental collision the eocene remnant carpathian flysch basin rcfb was still subducting the carpathians and eastern parts of the alps started to occupy the region of the present carpathians during the early miocene the oceanic plate underlying the rcfb subducted southwestwards later westwards while the northeastward and eastward migration velocity of the accreting plate boundary decreased through time the slower subduction rate caused a steeper dip of the subducting slab the beginning of the eggenburgian 22 19 ma and following duration of extension in the orogenic hinterland accompanied by the asthenosphere upwelling the onset of the crustally derived volcanism above the risen asthenosphere and the younger mantle derived volcanism progressively less contaminated by the crustal material all contemporaneous with a shortening in the carpathian accretionary wedge the subduction of the rcfb finally led at the end of the early miocene to a collision with the continental margin along the westernmost part of the present carpathian arc the subduction roll back of the subducting slab of the rcfb under the advancing inner carpathians the oblique closure of the basin the progressive change of the subduction to collision from the west to the east along the carpathian arc drove a scissors like break off of the subducting oceanic slab along the west carpathians the break off in the east carpathians was driven by the weight of a subducting oceanic slab and buoyancy of the attached continental slab the break off started in the west of the carpathian arc in the early miocene ran along the arc to its present position in the bend area between the east and south carpathians and separated the oceanic slab that subducted passively under its own weight from the european continental margin the lateral propagation rate of the slab tear decreased with time the break off related volcanism was synchronous with the final stages of the collision

dynamics of downwelling in an eddy resolving convective basin the mean downwelling in an eddy resolving model of a convective basin is concentrated near the boundary where eddies are shed from the cyclonic boundary current into the interior it is suggested that the buoyancyforced downwelling in the labrador sea and the lofoten basin is similarly concentrated in analogous eddy formation regions along their eastern boundaries use of a transformed eulerian mean depiction of the density transport reveals the central role eddy fluxes play in maintaining the adiabatic nature of the flow in a nonperiodic region where heat is lost from the boundary current the vorticity balance in the downwelling region is primarily between stretching of planetary vorticity and eddy flux divergence of relative vorticity althougha narrowviscous boundarylayeris ultimately importantin closingtheregionalvorticitybudget this overall balance is similar in some ways to the diffusive viscous balance represented in previous boundary layer theories and suggests that the downwelling in convective basins may be properly represented in lowresolution climate models if eddy flux parameterizations are adiabatic identify localized regions of eddy formations and allow density to be transported far from the region of eddy formations

graphitization of organic matter and fluid deposited graphite in palaeoproterozoic birimian black shales of the kaya goren greenstone belt burkina faso west africa palaeoproterozoic black shales form an essential part of the birimian volcanosedimentary belt in burkina faso west africa the mean rmax values and the atomic h c values of the bulk carbonaceous matter bcm together with rock structures and mineral assemblages indicate that these carbon rich rocks were metamorphosed to sub greenschist and low grade greenschist facies x ray diffraction reveals that the 002 graphite peak width in half maximum fwhm ranges from 0 43 to 0 71 2 in sub greenschist facies and from 0 27 to 0 41 2 in greenschist facies rocks but the d 002 values in both groups of rocks are approximately the same 3 35 a the bcm of individual samples is composed of particles with very variable shape reflectance and raman spectra type i particles that predominate in sub greenschist facies are fine grained irregular or elongate bodies 1 to 3 m in size their maximum reflectance rmax ranges between 2 5 and 8 2 and raman parameters r1 and r2 range from 0 5 to 1 4 and 0 5 to 0 8 respectively type ii particles are lath shaped up to 40 m large bodies commonly arranged parallel to white mica flakes the number of these particles increases from sub greenschist to greenschist facies maximum reflectance varies between 6 and 11 2 and r1 and r2 raman parameters range from 0 05 to 0 7 and from 0 1 to 0 5 respectively type iii particles occur in hydrothermally altered and sheared rocks these are nodular aggregates composed of grains up to 10 m in size this type of particles has very high reflectance rmax 11 15 and its raman spectra indicate a very high degree of structural ordering corresponding to well ordered graphite type i particles represent original organic matter in the metasediments type ii particles are believed to have been formed either in situ by solid state transformation of type i particles or by crystallization from metamorphic fluids gradual graphitization of the type i organic particles and the growth of lath shaped type ii particles from a fluid phase is assumed to have taken place under the peak metamorphic conditions associated with the burial of birimian sediments during thrust tectonism progressive tectonic accretion and crustal thickening during the d1 event of the eburnean orogeny the growth of equant high reflectance postkinematic nodular aggregates of type iii particles is ascribed to the reduction of co2 rich fluids during a hydrothermal event associated with late eburnean d2 exhumation and strike slip movements type i carbonaceous particles were only slightly affected by high temperature low pressure contact metamorphism during intrusion of late eburnean magmatic bodies whereas formation of type ii or iii particles was not recorded in contact metamorphosed rocks at all

continuity and episodicity in the early alpine tectonic evolution of the western carpathians how large scale processes are expressed by the orogenic architecture and rock record data

the contrasting dynamics of the buoyancy forced lofoten and greenland basins abstractthe nordic seas are commonly described as a single basin to investigate their dynamics and sensitivity to environmental changes when using a theoretical framework here we introduce a conc

review of neogene and quaternary volcanism of the carpathian pannonian region abstract development of the pannonian basins as well as thrusting and folding of the carpathians was accompanied by widespread volcanic activity this volcanism can be divided into three main genetic types 1 1 early miocene mainly acidic volcanism tuffs and ignimbrites the recent spatial separation of these volcanics may be due to large right lateral displacement along the mid hungarian shear zone during the early miocene 2 2 middle miocene pliocene calc alkaline mainly intermediate stratovolcanic complexes in the inner western carpathians and in the east carpathians related to a subducted oceanic slab their geochemical compositions show a transitional character between active continental margin and island arc type magmatic rocks the thickness of the crust increased with time and from west to east beneath this volcanic arc 3 3 pliocene pleistocene alkali basaltic volcanism was related to an upwelling then cooling asthenospheric dome this is thought to have initiated the thermal regime from which these melts ascended the compositional difference in space and in time might reflect the existence of local individual small sized diapiric bodies as well as several processes e g fractional crystallization mixing which modified the original magma the eruption of these basaltic melts was temporally associated with the final phase of development of the pannonian basin this volcanism was associated with recent uplifts and tectonic rejuvenation of the area

paleogene early miocene igneous rocks and geodynamics of the alpine carpathian pannonian dinaric region an integrated approach a review of paleogene early miocene igneous rocks of the alpine carpathianpannonian dinaric region is presented in this paper we attempt to reveal the geodynamic link between paleogene early miocene igneous rocks of the mid hungarian zone and those of the alps and dinarides our summary suggests that paleogene early miocene igneous rocks of all these areas were formed along a single subduction related magmatic arc the study also highlights orthopyroxene rich websterite mantle xenoliths from west hungary and east serbia that were formed in the vicinity of a subducted slab we discuss the location and polarity of all potential subduction zones of the area that may account for the igneous rocks and orthopyroxene rich mantle rocks however results of seismic tomography on subducted slabs beneath the studied area combined with geological data demonstrate that igneous rocks and mantle rocks cannot be explained by the same subduction process we propose that the paleogene early miocene arc was mainly generated by the budva pindos subduction zone subordinately by penninic subduction whereas mantle rocks were possibly formed in the vicinity of the older vardar subduction zone continental blocks possibly moved together with their mantle lithosphere the present diverging shape of the proposed arc has been achieved by considerable shear and rotations of those lithospheric blocks

variability of the norwegian atlantic current and associated eddy field from surface drifters the norwegian atlantic current nwac and its eddy field are examined using data from surface drifters the data set used spans nearly 20 years from june 1991 to december 2009 the results are largely consistent with previous estimates which were based on data from the first decade only with our new data set statistical analysis of the mean fields can be calculated with larger confidence the two branches of the nwac one over the continental slope and a second further offshore are clearly captured the norwegian coastal current is also resolved in addition we observe a semipermanent anticylonic eddy in the lofoten basin a feature seen previously in hydrography and in models the eddy kinetic energy eke is intensified along the path of the nwac with the largest values occurring in the lofoten basin the strongest currents exceeding 100 cm s 1 occur west of lofoten lateral diffusivities were computed in five domains and ranged from 1 5 107 cm2 s 1 the lagrangian integral time and space scales are 1 2 days and 7 23 km respectively the data set allows studies of seasonal and interannual variations as well the strongest seasonal signal is in the nwac itself as the mean flow strengthens by approximately 20 in winter the eke and diffusivities on the other hand do not exhibit consistent seasonality in the sampled regions there are no consistent indications of changes in either the mean or fluctuating surface velocities between the 1990s and 2000s

on the flow of atlantic water and temperature anomalies in the nordic seas toward the arctic ocean the climatic conditions over the arctic ocean are strongly influenced by the inflow of warm atlantic water conveyed by the norwegian atlantic slope current nwasc based on sea surface height ssh data from altimetry we develop a simple dynamical measure of the nwasc transport to diagnose its spatio temporal variability this supports a dynamical division of the nwasc into two flow regimes the svinoy branch svb in the southern norwegian sea and the fram strait branch fsb west of spitsbergen the svb transport is well correlated with the ssh and atmospheric variability within the nordic seas factors that also affect the inflow to the barents sea in contrast the fsb is influenced by regional atmospheric conditions around svalbard and northern barents sea using a composite analysis we further relate anomalous strong svb flow events to temperature fluctuations along the core of atlantic water a warm composite anomaly is found to propagate northward with a tendency to amplify enroute after these events a roughly 12 months delayed temperature signal is identified in the fsb however also in the lofoten basin interior a delayed temperature signal is found which appears to originate from the nwasc this study suggests that hydrographic anomalies both upstream from the north atlantic and locally generated in the norwegian sea are important for the oceanic heat and salt transport that eventually enters into the arctic

combined u pb and u th he geochronometry of basalt maars in western carpathians implications for age of intraplate volcanism and origin of zircon metasomatism the age of intraplate volcanism in northern pannonian basin of carpathians is revisited using a combination of zircon u pb zircon u th he and apatite u th he dating techniques complemented by electron microprobe emp characterisation of dated minerals a total of six maar structures and diatremes in the south slovakian volcanic field ssvf were dated and the obtained new ages yielded the following key findings two isolated maars in se part indirectly dated by geomorphologic constraints to late pleistocene are actually of pliocene 2 8 0 2 ma and late miocene 5 5 0 6 ma ages in contrast two maars in nw part of the study area are of late pliocene age 4 1 0 4 and 5 2 5 4 ma younger than the late miocene age 6 5 ma inferred previously from k ar data on the proximal basaltic lava flows these maars therefore belong to the second volcanic phase that was previously identified only in se part of the ssvf in the light of the new geochronologic data it seems likely that the pliocene phreatomagmatic eruptions may have occurred along extension related nw and ne trending orthogonal faults emp analyses and imaging revealed an extensive syn and post growth metasomatic replacement by dissolution reprecipitation in the majority of zircons abundant silicate melt inclusions in porous metasomatised parts of the zircons are diagnostic of magmatic rather than hydrothermal metasomatism consistent ages of the metasomatised and non metasomatised zones do not indicate disturbance of the u pb system during the metasomatism enrichment in u and th loss in the metasomatised zircons are diagnostic of an increasing oxygen fugacity triggered by degassing of the volatile residual melt during the final stages of alkali basalt fractionation rare zircon to baddeleyite transformation was probably connected with lowered silica activity in carbonated basaltic magmas in south eastern part of the study area

vertical structure and seasonal variability of the inflow to the lofoten basin inferred from high resolution lagrangian simulations the lofoten basin in the eastern nordic seas plays a central role in modifying the warm atlantic water inflow toward the arctic ocean here the atlantic water experiences increased residence times

evolution of late neoproterozoic to early paleozoic tectonic elements in central and southeast european alpine mountain belts review and synthesis abstract late neoproterozoic to early paleozoic cadomian tectonic elements are widespread in the southeastern alpine mediterranean mountain belts with discontinuous exposure extending from the alps to the menderes massif in turkey the sequences include voluminous plutonic island and continental arc successions some ophiolites of variable late neoproterozoic and cambrian to early ordovician ages high to medium grade metamorphic sequences and subordinate metasediments geological and geochronological data suggest that these cadomian elements partly experienced tectonothermal activity including metamorphism and magmatism between ca 650 and 600 ma followed by further i and s type plutonism in an andean type continental margin setting ca between 570 and 520 ma subsequently a major rift zone developed which resulted in continental stretching and subsequent formation of a back arc basin which is dated as late cambrian rifting is followed by oceanic spreading which commenced ca at the cambrian ordovician boundary possibly in a back arc setting this tectonic scenario suggests that alpine mediterranean cadomian tectonic elements were accreted to gondwana during early cadomian events ca 600 650 ma subsequently they were likely part of a long lasting outer subduction zone of gondwana at the margin of a panthalassa type ocean during late neoproterozoic iii and cambrian due to back arc spreading continental pieces started to split off from gondwana ca at the cambrian ordovician boundary

petrological and kar and40ar39ar age constraints for the tectonothermal evolution of the high pressure meliata unit western carpathians slovakia abstract the meliata high pressure unit exposed in the southern part of the western carpathians consists of four groups of rocks which are characterized by different lithologies and metamorphic histories 1 the most common are triassic marbles intercalated with metabasalts and glaucophane bearing phyllites phengite from metabasalts and phyllites record k ar and40ar 39ar plateau ages of 152 155 ma which are interpreted to date the high pressure metamorphism 2 blueschist facies mafic rocks and subordinate glaucophane bearing micaschists devoid of marbles which contain relic low si muscovite and newly formed high si phengite the40ar 39ar data obtained for the micas indicate palaeozoic ages of 375 380 ma for the early amphibolite facies muscovite and a 250 ma age for the secondary blueschist facies phengite 3 glaucophane free phyllites and phengite quartzite with low si and high si micas respectively textural features indicate a polyphase evolution characterized by a greenschist facies metamorphism followed by a blueschist facies overprint the high si micas provide evidence for an early middle jurassic age 172 ma of the high pressure metamorphism 4 amphibolite facies slices and blocks overprinted by blueschist facies metamorphism represent old basement rocks regarding the differences in lithologies metamorphic conditions and radiometric ages of high pressure micas older age for continental vs younger age for oceanic rocks subduction of a continental wedge prior to that of oceanic crust can be assumed this interpretation is based also on palaeogeographical reconstruction of the mesozoic western tethys between the apulian promontory and the tisza bihor continental block

the influence of topography on the stability of the norwegian atlantic current off northern norway abstractthe steep continental slope off the lofoten vesteralen islands of northern norway appears to be the source of the most intense mesoscale eddy field in all of the nordic seas here we use li

in pursuit of anomalies analyzing the poleward transport of atlantic water with surface drifters we examine the trajectories of 168 drifters as a proxy for atlantic water flowing through the nordic seas the drifters were released at or passed through the svinoy section off the west coast of norway for comparison we generate a set of synthetic trajectories using a stochastic model with a range of diffusivities with the both sets we determine the transit times of both drifters and particles from svinoy to arctic gateways the barents sea and spitsbergen the mean arrival times to these locations are roughly 200 and 500 days respectively this implies ample time for cooling of the surface waters which increases densities and permits subduction before reaching the arctic however a range of transit times is seen some parcels reach fram strait in only 4 months while others are still in the southern nordic seas after 2 years the results do not support the idea that temperature or salinity anomalies can exist as coherent packets the drifters passing svinoy when treated as a group quickly spread over large distances mixing with water in the norwegian and lofoten basins thus an anomaly entering the nordic seas would quickly be obliterated however the velocity of the clusters center of mass is consistent with anomaly propagation speeds inferred previously from hydrographic measurements suggesting the observed variability is advective in nature

observed and modeled surface eddy heat fluxes in the eastern nordic seas large scale budget calculations and numerical model process studies suggest that lateral eddy heat fluxes have an important cooling effect on the norwegian atlantic current nwac as it flows through the nordic seas but observational estimates of such fluxes have been lacking here wintertime surface eddy heat fluxes in the eastern nordic seas are estimated from surface drifter data satellite data and an eddy permitting numerical model maps of the eddy heat flux divergence suggest advective cooling along the path of the nwac integrating the flux divergence over temperature classes yields consistent estimates for the three data sets the waters warmer than about 6 c are cooled while the cooler waters are warmed similar integrations over bottom depth classes show that regions shallower than about 2000 m are cooled while deeper regions are warmed finally integrating the flux divergence along the core of the nwac suggests that the highest eddy induced heat loss at the surface is along the steepest part of the continental slope east of the lofoten basin the model fields indicate that cooling of the current by lateral eddy fluxes is comparable to or larger than the local heat loss to the atmosphere

near surface circulation of the nordic seas as measured by lagrangian drifters in the period june 1991 to august 1993 107 argos tracked drifters drogued to 15 m depth were released in the nordic seas or greenland iceland and norwegian seas the drifter movements revealed the strong and spatially confined current systems along the surface salinity fronts of the iceland faroe frontal zone and of the norwegian coast and along the continental margins and their extensions to the barents sea and spitsbergen the norwegian atlantic current is composed of three distinct streams two continental margin and one coastal branches which join into one single swift mean current west of the lofoten and vesteralen islands where the strongest measured currents are in excess of 110 cm s 1 in addition to the general cyclonic gyre circulation in the nordic seas the drifters indicate smaller cyclonic circulation patterns in all the major subbasins i e the iceland plateau the norwegian the lofoten and the greenland basins no surface signature of the east icelandic current is disclosed by the drifters interpolated and low pass filtered position data were used to construct maps of 15 m depth ensemble mean velocity velocity variability and residence time vigorous eddy fields are dominant in the strong currents and in the lofoten basin eulerian correlations indicate that they tend to propagate to the west in contrast the iceland plateau appears quiescent both in the mean and eddy velocities single particle diffusivities are computed and are found to be in the range 1 7 107 cm2 s 1 the corresponding lagrangian timescale and space scale are 1 3 days and 10 40 km respectively these lagrangian drifter measurements compose the first basin scale accurate near surface velocity data set of the nordic seas

origin of sulfide inclusions in cumulate xenoliths from nograd gomor volcanic field pannonian basin north hungary south slovakia abstract we provide new information about the evolution of the lithosphere beneath the nograd gomor volcanic field ngvf northern pannonian basin based on sulfide inclusions in cumulate origin ultramafic xenoliths the clinopyroxene rich cumulate xenoliths representing the lower crust and upper mantle underwent metasomatic alteration which resulted in formation of amphiboles we have carried out a detailed petrographic observation on sulfide inclusions using reflected light microscope and analyzed numerous back scattered electron images of the most typical sulfide blebs based on the petrographic study only rounded elongated or negative crystal shaped single inclusions occurring randomly in clinopyroxene and amphibole and rarely in olivine and spinel have been selected for detailed electron microprobe analysis the size of these single inclusions ranges from 3 to 75 m in diameter the sulfide blebs consist mostly of pyrrhotite and minor chalcopyrite pentlandite and cubanite pyrrhotite which is the major phase in all the inclusions is ni poor max 6 1 wt chalcopyrite is deficient in cu content 28 9 wt pentlandite and cubanite show regular compositions and were identified only in one xenolith the bulk compositions of sulfide blebs show a tight compositional range and are rich in fe compared to those in type i peridotite xenoliths from the same volcanic field geochim cosmochim acta 59 1995 3917 falus gy 2000 geochemical significance of sulfide inclusions of cr diopsidic xenoliths of alkaline basalts occurring in the carpathian pannonian region msc thesis department of petrology and geochemistry eotvos university budapest the sulfide blebs studied likely formed from a sulfide melt coexisting with a silicate melt the latter melt was the source of host clinopyroxene rich cumulates the sulfide blebs mineralogically pyrrhotite experienced a high and low temperature evolution producing further sulfide phases chalcopyrite pentlandite cubanite present in the blebs

dating the lower crust by ion microprobe ion microprobe uthpb ages of zircons from granulite facies lower crustal xenoliths from north queensland australia correlate well with the ages of major orogenic episodes manifest at the earth s surface about half of the xenoliths contain proterozoic zircons which are similar in age to the episodes of high grade metamorphism of the older surface rocks all the xenoliths contain late paleozoic zircons which show a real 100 ma range in206pb238 u ages from 320 to 220 ma which is attributed to granulite facies metamorphism followed by slow cooling in the deep crust the paleozoic zircon ages coincide in time with the prolonged episode of eruption of voluminous felsic ash flows and intrusion of high level granites in this region 320 270 ma mineral and melt inclusions in the zircons provide clues to the origin of some of the xenoliths and coupled with the age information can be used to infer the geological processes operating in the lower crust the zircons from two mafic xenoliths contain felsic and intermediate melt inclusions implying at least a two stage history for these rocks involving either partial melting of a more felsic protolith or crystal accumulation from an evolved melt some of the zircons from the felsic xenoliths contain co2 rich fluid inclusions indicating that those zircons grew during high grade metamorphism the isotopic and chemical data for the whole rock xenoliths show that they originate from a segment of the lower crust which is a heterogeneous mixture of supracrustal and mafic mantle derived lithologies the major orogenic event responsible for the formation of that crust occurred in the late paleozoic when proterozoic supracrustal rocks were emplaced into the lower crust possibly along thin skinned thrust slices this was accompanied by intrusion of high temperature mantle derived melts which caused partial melting of pre existing crust the most likely setting for such tectonism is a continental margin subduction zone

boundary currents and watermass transformation in marginal seas the properties of watermass transformation and the thermohaline circulation in marginal seas with topography and subject to a spatially uniform net surface cooling are discussed the net heat loss within the marginal sea is ultimately balanced by lateral advection from the open ocean in a narrow boundary current that flows cyclonically around the basin heat loss in the interior is offset by lateral eddy fluxes originating in the boundary current the objectives of this study are to understand better what controls the density of waters formed within the marginal sea the temperature of the outflowing waters the amount of downwelling and the mechanisms of heat transport within the marginal sea the approach combines heat budgets with linear stability theory for a baroclinic flow over a sloping bottom to provide simple theoretical estimates of each of these quantities in terms of the basic parameters of the system the theory compares well to a series of eddy resolving primitive equation model calculations the downwelling is concentrated within the boundary current in both a diffusive boundary layer near topography and an eddy driven region on the offshore edge of the boundary current for most high latitude regions the horizontal gyre is expected to transport more heat than does the overturning gyre

paleogene retroarc flexural basin beneath the neogene pannonian basin a geodynamic model abstract the neogene middle miocene recent pannonian basin is superimposed on an earlier paleogene middle eocene early miocene basin complex as a result of back arc extension although the stratigraphy of the latter is very well known due to raw material exploration its formation and structural evolution is much less understood a transtensional origin was generally proposed for the paleogene basin of hungary assuming an origin analogous to that of the overlying neogene pannonian basin we suggest an alternative geodynamic scenario for the development of the paleogene basin complex as we think that the observations are better understood in terms of a retroarc foredeep basin model according to this a flexural basin developed south of the backthrust inner west carpathian units the thrust load resulted in a generally deep underfilled flysch basin during middle eocene early oligocene times in the late oligocene early miocene predominantly shallow marine and continental deposition occurred indicating the gradual cessation of thrusting in the adjacent thrust fold belt and the beginning of molasse sedimentation throughout the whole paleogene a shift can be observed of the bathyal dominantly siliciclastic in the axis of the foredeep and neritic partly carbonate in the foreland flank of the foredeep facies belts this migration of the middle eocene early miocene depocenters of the hpb hungarian paleogene basin to the east northeast in present day coordinates is the result of two processes 1 1 the advancement of backthrusting to the southeast 2 2 along strike shift of thrusting to the northeast while a thin skinned thrust front can be reconstructed for the late eocene buda anticline the diosjeno hurbanovo line is interpreted as the result of a major thick skinned thrusting event at the base of the np24 zone 31 ma the subsidence pattern the distinct depositional environments and the structural observations can be more easily integrated into a flexural basin model than into a wrench basin model based on the flexural basin model of this work the early tertiary western carpathians formed a compressional arc while this arc probably developed above a b subduction zone during the late eocene with a corresponding trench magura a forearc basin central carpathian or podhale and a retroarc flexural basin hungarian paleogene from the early oligocene to the early miocene it was characterized by a subduction with a corresponding peripheral foredeep dukla and silesian and a retroarc flexural basin hungarian paleogene

immiscible separation of metalliferous fe ti oxide melts from fractionating alkali basalt p t f o2 conditions and two liquid elemental partitioning globules of iron dominated 59 69 wt feotot and titanium dominated 43 5 wt tio2 oxide melts have been detected in igneous xenoliths from pliocene to pleistocene alkali basalts of the western carpathians fluid inclusion and mineral composition data indicate immiscible separation of the high iron oxide melt him at magmatic temperatures the him separation occurred during clinopyroxene augite accumulation in an alkali trachybasalt and continued during crystallization of amphibole kaersutite and k feldspar anorthoclase the latter coexisting with trachyte and alkalic rhyolite residual melts some him was also expelled from sub alkalic rhyolite 70 77 sio2 coexisting with an27 45 plagioclase and quartz in granitic tonalite trondhjemite xenoliths oxygen fugacities during him separation range from 1 4 to 0 6 log units around the qfm buffer a close genetic relationship between him hosted xenoliths and mantle derived basaltic magma is documented by mineral 18o values ranging from 4 9 to 5 9 v smow d values of gabbroic kaersutite between 61 and 86 v smow are in agreement with a presumed primary magmatic water source most trace elements except li rb and cs have preferentially partitioned into the him the him si melt partition coefficients for transition elements sc v cr co ni and base metals zn cu mo are between 2 160 resulting in extreme enrichment in the him la and ce also concentrate in the silicic melt whereas tb tm in the him hence the immiscible separation causes ree fractionation and produces residual silicic melt enriched in lree and depleted in hree the weak fractionation among tb tm and yb lu can be attributed to recurrent extraction of the him from the magmatic system while flat hree chondrite normalized patterns are interpreted to indicate no or little loss of the him

origin and provenance of 2 ma 2 ga zircons ejected by phreatomagmatic eruptions of pliocene basalts in southern slovakia u pb ages of zircons recovered from pliocene pyroclastic deposits in northern part of the cenozoic intra carpathian back arc basin pannonian basin span the interval from pliocene 2 2 ma to paleoproterozoic orosirian rhyacian 1850 2115 ma the scattered u pb ages reflect eruption ages of the host basaltic volcanic centres two episodes of post eocene magmatic crustal growth and the possible tectonic affiliation provenance and age of the subjacent basement or the sedimentary basin detritus sampled by the basaltic magma the youngest zircons define the maximum ages of phreatomagmatic eruptions during the late miocene pliocene extension these zircons are distinguished from older zircons by zr hf 40 90 and th u ratios 0 5 4 5 as well as super chondritic ehf t values ranging from 7 to 14 indicating mantle derived parental magmas the locally increased th u ratios up to 8 accompanied by zr hf 60 are diagnostic of evolved phonolite parental melt hence the youngest zircons can be interpreted as antecrysts originating from evolved melts cogenetic with the host alkali basalts in contrast older zircons represent xenocrysts scavenged by the uprising basalt from surrounding rocks subordinate eocene early oligocene 29 38 ma sub group of zircon xenocrysts is coincidental with the magmatism and volcanism along the periadriatic lineament and the middle hungarian zone the early miocene 18 ma cluster is coeval with the deposition of the bukk mountains felsic ignimbrite correlated with the onset of the back arc extension that triggered miocene sedimentation within the pannonian basin the eocene early oligocene zircons have been likely scavenged from pyroclastic and ash fall deposits of the palaeogene retroarc basin subjacent to the miocene basin infilling sub chondritic ehf t values between 2 5 and 8 in the eocene early miocene zircons attest their crystallization from subduction related felsic to intermediate melts containing large amounts of recycled crustal material palaeozoic proterozoic zircons create a heterogeneous population with variable trace element abundances and ehf t values the determined age clusters are reminiscent of some basement units cropping out recently in central western carpathians zircon hf isotope data indicate recycling of up to 3 4 ga old mafic crust and also the presence of 2 ga old juvenile mafic crust these units had either underlain the northern part of the pannonian basin during pliocene or had been exposed during the deposition of miocene clastic sediments the absence of mesoproterozoic grenvillian zircons 0 9 1 8 ga in the pre cenozoic population of zircon xenocrysts is provisionally interpreted as indicating the evolution of the zircon source area within the west african craton

observations of the labrador sea eddy field this paper is an observational study of small scale coherent eddies in the labrador sea a region of dense water formation thought to be of considerable importance to the north atlantic overturning circulation numerical studies of deep convection emphasize coherent eddies as a mechanism for the lateral transport of heat yet their small size has hindered observational progress a large part of this paper is therefore devoted to developing new methods for identifying and describing coherent eddies in two observational platforms current meter moorings and satellite altimetry details of the current and water mass structure of individual eddy events as they are swept past by an advecting flow can then be extracted from the mooring data a transition is seen during mid 1997 with long lived boundary current eddies dominating the central labrador sea year round after this time and convectively formed eddies similar to those seen in deep convection modeling studies apparent prior to this time the topex poseidon altimeter covers the labrador sea with a loose net of observations through which coherent eddies can seem to appear and disappear by concentrating on locating and describing anomalous events in individual altimeter tracks a portrait of the spatial and temporal variability of the underlying eddy field can be constructed the altimeter results reveal an annual pulsation of energy and of coherent eddies originating during the late fall at a particular location in the boundary current pinpointing the time and place of the boundary current type eddy formation the interannual variability seen at the mooring is reproduced but the mooring site is found to be within a localized region of greatly enhanced eddy activity notably lacking in both the annual cycle and interannual variability is a clear relationship between the eddies or eddy energy and the intensity of wintertime cooling these eddy observations as well as hydrographic evidence suggest an active role for boundary current dynamics in shaping the energetics and water mass properties of the interior region

neotethys closure history of anatolia insights from 40ar 39ar geochronology and p t estimation in high pressure metasedimentary rocks the multiple high pressure hp low temperature lt metamorphic units of western and central anatolia offer a great opportunity to investigate the subduction and continental accretion related evolution of the eastern limb of the long lived aegean subduction system recent reports of the hp lt index mineral fe mg carpholite in three metasedimentary units of the gondwana derived anatolide tauride continental block namely the afyon zone the oren unit and the southern menderes massif suggest a more complicated scenario than the single continental accretion model generally put forward in previous studies this study presents the first isotopic dates white mica 40ar 39ar geochronology and where possible are combined with p t estimates chlorite thermometry phengite barometry multi equilibrium thermobarometry on carpholite bearing rocks from these three hp lt metasedimentary units it is shown that in the afyon zone carpholite bearing assemblages were retrogressed through greenschist facies conditions at c 67 62 ma early retrograde stages in the oren unit are dated to 63 59 ma in the kurudere nebiler unit hp mesozoic cover of the southern menderes massif hp retrograde stages are dated to c 45 ma and post collisional cooling to c 26 ma these new results support that the oren unit represents the westernmost continuation of the afyon zone whereas the kurudere nebiler unit correlates with the cycladic blueschist unit of the aegean domain in western anatolia three successive hp lt metamorphic belts thus formed the northernmost tavsanli zone c 88 82 ma the oren afyon zone between 70 and 65 ma and the kurudere nebiler unit c 52 45 ma the southward younging trend of the hp lt metamorphism from the upper and internal to the deeper and more external structural units as in the aegean domain points to the persistence of subduction in western anatolia between 93 90 and c 35 ma after the accretion of the menderes tauride terrane in eocene times subduction stopped leading to continental collision and associated barrovian type metamorphism because by contrast the aegean subduction did remain active due to slab roll back and trench migration the eastern limb below southwestern anatolia of the hellenic slab was dramatically curved and consequently teared it therefore is suggested that the possibility for subduction to continue after the accretion of buoyant e g continental terranes probably depends much on palaeogeography

stationary sea surface height anomalies in cyclonic boundary currents conservation of potential vorticity and deviations from strict topographic steering abstractin high latitude subpolar seas such as the nordic seas and the labrador sea time mean geostrophic currents mediate the bulk of the meridional oceanic heat transport these currents are primarily encountered along the continental slopes as intense cyclonic boundary currents which because of the relatively weak stratification should be strongly steered by the bottom topography however analyses of hydrographic and satellite altimetric data along depth contours in nordic seas boundary currents reveal some remarkable stationary along stream variations in the depth integrated buoyancy and bottom pressure a closer examination shows that these variations are linked to changes in steepness and curvature of the continental slope to examine the underlying dynamics a steady state model of a cyclonic stratified boundary current over a topographic slope is developed in the limit of small rossby numbers based on potential vorticity conservation equations for the zeroth and first order pressure and

iib trioctahedral chlorite from the barberton greenstone belt crystal structure and rock composition constraints with implications to geothermometry iib trioctahedral chlorite in the barberton greenstone belt bgb metavolcanic rocks was formed during pervasive greenschist metamorphism the chem ical composition of the chlorite is highly variable with the fe fe mg ratio ranging from 0 12 to 0 8 among 53 samples the chemical variation of the chlorite results from the chemical diversity of the host rock especially the mgo content of the rock but major details of the variation pattern of the chlorite are due to the crystal structure of the chlorite all major cation abundances in the chlorite are strongly correlated with each other sil icon increases with mg and decreases with fe while aliv and alvi decrease with mg and increase with fe2 a complex exchange vector explains over 90 of the chlorite compositional variation mg4sife2 3alvi 1 aliv 1 which has 3 parts fe mg substitution coupled with one part tschermakite substitution this ratio is required to maintain the charge and site balances and the dimensional fit between the tetrahedral and octahedral sheets the subtle change in al substitution in chlorite implies that alvi is preferentially ordered in the m 4 site and about 84 of the alvi present is in the m 4 sites when they are nearly filled with alvi based on 47 analyzed chlorite bearing rock samples chlorite chl composition is strongly correlated with the mgo content of the host rock calculated correlation coefficients are 0 91 for sio2chl mgorock 0 87 for al2o3chl mgorock 0 89 for mgochl mgorock and 0 85 for feochl mgorock only weak correlations have been found between chlorite oxides and other oxides of rock between same oxides in chlorite and rock sio2 0 67 al2o3 0 59 feo 0 41 however mgochl is saturated at about 36 wt in rocks that have mgo above 22 wt the mgochl is about 5 wt when the host rock approaches 0 wt of mgo this implies that mg substituting into the chlorite is approximately limited to 1 5 9 2 mg atoms per formula unit and 1 0 3 2 aliv chlorite geothermometers can not be applied to all bgb samples however the empirical chlorite geothermometer based on aliv of chlorite may be applicable to chlorites formed under metamorphic conditions because it can predict the chemical composition of the chlorite from basaltic and dacitic samples in this study an estimated temperature of about 320 c for the greenschist metamorphism of the greenstone belt through this geothermometer is consistent with that obtained by other geothermometers

chemical and spectroscopic characteristics of potassium white micas related to polystage evolution of the central western carpathians orogenic wedge abstract potassium white micas in sheared basement and cover rocks from the central western carpathians cwc were investigated by pl microscopy electron microprobe emp analysis mossbauer and micro raman spectroscopy we specified chemical and spectroscopic characteristics which allow distinction between celadonite poor muscovitic and celadonite rich phengitic white mica wmca wmca generations formed during a polystage evolution in changing p t conditions ranging from the very low to medium temperatures at medium pressure within the alpidic cwc orogenic wedge bse imaging emp analyses and x ray element maps indicate chemical differences between muscovite and phengite mainly in al fe and si contents mossbauer spectroscopy revealed their contrasting spectra related to different hyperfine parameters mainly of quadrupole splitting qs of ms 2 6 2 7 mm s or 2 9 3 0 mm s for phg corresponding to fe2 and fe3 contents blastomylonitic samples with a single dominating wmca generation and finite strain xz sections were suitable for micro raman study these data corroborate correlation between the frequencies of two vibrational modes of wmca and si content the investigated wmca generations indicate an enhanced transformation between wmca phases in shear zones

structural styles in mesozoic and cenozoic melanges in the western cordillera of north america the term melange is currently used to describe several different kinds of mudstone rich rocks that are broadly characterized by an obscure stratigraphy stratal disruption or a chaotic block in matrix fabric four types of melange which can be defined in outcrop on the basis of mesoscopic fabric and lithologic composition are particularly widespread and distinctive type i includes sequences of originally interbedded sandstone and mudstone that record incipient to thorough disruption and fragmentation of strata accomplished largely by layer parallel extension type ii consists of similarly deformed thin layers of green tuff radiolarian ribbon chert and minor sandstone originally interbedded with black mudstone disruption in both types i and ii which probably occurred while the sediments were incompletely consolidated has been ascribed to either imbricate faulting in accretionary wedges or gravitationally driven deformation type iii comprises inclusions of diverse shapes sizes and compositions enveloped in a locally scaly pelitic matrix the ultimate source of fragments is obscure because the majority were not derived by either the progressive disruption of interbedded sediments or in situ tectonic plucking and abrasion of adjacent rocks although some type iii melanges may have originated deep within accretionary prisms final emplacement as olistostromes muddy debris flow deposits or mud diapirs seems likely type iii melanges are mechanically analogous to scaly sheared serpentinites many probably have been tectonically remobilized or even intruded into shallow level fault zones type iv consists of lenticular inclusions bounded by an anastomosing network of subparallel faults their fabric records progressive slicing in brittle fault zones each of the four types of melange described here could in theory have formed in a variety of settings on or within an accretionary wedge at an active convergent margin none can yet be singled out as a uniquely diagnostic subduction melange

p t deformation fe3 fe2 mapping at the thin section scale and comparison with xanes mapping application to a garnet bearing metapelite from the sambagawa metamorphic belt japan quantitative x ray maps of composition from a chlorite k white mica albite quartz and garnet bearing thin section from a sambagawa blueschist facies metapelite were combined with a multiequilibrium calculation method to calculate a p t fe3 fe2 deformation map at the millimetre scale the studied sample was chosen because elongated chlorite crystallization tails pressure shadows rimmed by phengite are present which is an appropriate assemblage for the quantification of the p t evolution chlorite temperature and fe3 content maps were calculated by successive iterations for each pixel analysis of fe3 until convergence of the four chlorite quartz h2o equilibria that can be written using the fe and mg amesite clinchlore daphnite and sudoite chlorite end members the calculated map of fe2 fe3 in chlorite is in good qualitative agreement with the in situ mapping of this ratio using xanes x ray absorption near edge structure techniques the temperature map indicates that high temperature chlorite zones with low fe3 contents alternate with lower temperature zones and higher fe3 contents in the crystallization tail late fractures perpendicular to the elongation axis of the tail are filled by very low temperature chlorite 250 c showing fe3 fetotal up to 0 4 groups of chlorite and mica pixels were then identified based on compositional and structural criteria and a p tdeformation map was calculated using representative analyses of these groups the calculated p tdeformation map suggests that in contrast to chlorite the composition of most mica did not change significantly during exhumation mica reequilibrated in late ew shear bands only ew shearing was already active at 0 1 gpa 500 c which corresponds to the peak temperature and probably pressure conditions at reduced redox conditions the intensity of deformation probably decreased with decrease in temperature to 350 400 c at this temperature a second main deformation event corresponding to a further ew stretching occurred and was still active below 250 c and more oxidizing conditions these results indicate that the scale at which p t data can be obtained is now close to the scale of observation of structural geologists a close link between deformation and mineral reaction is therefore possible at the microscopic scale which provides information about the relationship between deformation and mineral reactivity the modalities of deformation with time and the p t conditions at which it occurred

isotopic zonations in silicic magma chambers many ash flow tuffs are zoned in radiogenic isotope ratios indicating that roofward assimilation of crust occurs in ash flow magma chambers prior to eruption cases where relatively well constrained calculations may be made regarding the percentage of assimilation in the roof zone indicate that the percentage of assimilation often exceeds the percentage of phenocrysts in the tuffs this relation in addition to the fact that assimilation gradients are opposite to that of the percentage of phenocrysts suggests that assimilation and crystallization in the silicic roof zones of crustal magma chambers are separated in time and space and that these processes are best modeled as two component mixing true assimilation fractional crystallization is probably restricted to the lower mafic parts most phenocrysts in the silicic upper parts of magma chambers crystallized after assimilation providing minimum estimates of time between assimilation and eruption 1 100 yr preservation of monotonic isotopic gradients suggests that convection is minor in the upper parts of silicic magma chambers during the late stages of evolution

a chlorite solid solution geothermometer the los azufres mexico geothermal system chlorite constitutes a major hydrothermal alteration product of metamorphism of andesites in the active geothermal system of los azufres mexico electron microprobe analyses performed on a set of crystals from each sample show wide variations in composition correlation coefficients among chemical constituents were calculated it is shown that the tetrahedral charge is positively correlated with the octahedral vacancy and negatively with the iron content and there is almost no correlation with the octahedral aluminium and magnesium content a procedure is proposed to select end members and substitution vectors and to give a general formula for these chlorites

very low grade metamorphic evolution of pelitic rocks under high pressure low temperature conditions nw new caledonia sw pacific the p t gradient in a late eocene low t high p metamorphic belt in northern new caledonia increases from sw to ne metapelites in the pumpellyite prehnite and blueschist zones contain lawsonite mg carpholite fe stilpnomelane and fe glaucophane thermodynamic calculations indicate a progression of metamorphic conditions from less than 0 3gpa and 250 c in a kaolinitebearing rock in the sw up to 1 5gpa and 410 c in a lawsonite glaucophane bearing sample in the ne of the diahot terrane through a multi method investigation of phyllosilicates organic matter and fluid inclusions we demonstrate that the evolution of organic matter and illite crystallinity depends strongly on the evolution of the p t path with time in addition we show that the illite muscovite b cell dimension provides a robust estimate of maximum pressure reached in low temperature domains with polyphase metamorphic histories despite subsequent hightemperature low pressure events fluid inclusion study reveals an isothermal decompression in the diahot terrane

quantifying mesoscale eddies in the lofoten basin the lofoten basin is the most eddy rich region in the norwegian sea in this paper the characteristics of these eddies are investigated from a comprehensive database of nearly two decades of satellite altimeter data 1995 2013 together with argo profiling floats and surface drifter data an automated method identified 1695 1666 individual anticyclonic cyclonic eddies in the lofoten basin from more than 10 000 altimeter based eddy observations the eddies are found to be predominantly generated and residing locally the spatial distributions of lifetime occurrence generation sites size intensity and drift of the eddies are studied in detail the anticyclonic eddies in the lofoten basin are the most long lived eddies 60 days especially in the western part of the basin we reveal two hotspots of eddy occurrence on either side of the lofoten basin furthermore we infer a cyclonic drift of eddies in the western lofoten basin barotropic energy conversion rates reveals energy transfer from the slope current to the eddies during winter an automated colocation of surface drifters trapped inside the altimeter based eddies are used to corroborate the orbital speed of the anticyclonic and cyclonic eddies moreover the vertical structure of the altimeter based eddies is examined using colocated argo profiling float profiles combination of altimetry argo floats and surface drifter data is therefore considered to be a promising observation based approach for further studies of the role of eddies in transport of heat and biomass from the slope current to the lofoten basin

middle late jurassic sedimentary melange formation related to ophiolite obduction in the alpine carpathian dinaridic mountain range abstract the middle late jurassic mountain building process in the western tethyan realm was triggered by west to northwestward directed ophiolite obduction onto the wider adriatic shelf this southeastern to eastern adriatic shelf was the former passive continental margin of the neo tethys which started to open in the middle triassic its western parts closed from around the early middle jurassic boundary with the onset of east dipping intra oceanic subduction ongoing contraction led to ophiolite obduction onto the former continental margin since the bajocian trench like basins formed concomitantly within the evolving thin skinned orogen in a lower plate situation deep water basins formed in sequence with the northwest westward propagating nappe fronts which served as source areas of the basin fills basin deposition was characterized by coarsening upward cycles i e sedimentary melanges as synorogenic sediments the basin fills became sheared successively by ongoing contractional tectonics with features of typical melanges analyses of ancient neo tethys melanges along the eastern mediterranean mountain ranges allow both a facies reconstruction of the outer western passive margin of the neo tethys and conclusions on the processes and timing of jurassic orogenesis comparison of melanges identical in age and component spectrum in different mountain belts figured out one neo tethys ocean in the western tethyan realm instead of multi ocean and multi continent scenarios

the evolution of illite to muscovite mineralogical and isotopic data from the glarus alps switzerland thirty five illite and muscovite concentrates were extracted from triassic and permian claystones shales slates and phyllites along a cross section from the diagenetic alpine foreland tabular jura and borehole samples beneath the molasse basin to the anchi and epimetamorphic helvetic zone of the central alps concentrates and thin sections were investigated by microscopic x ray infrared mossbauer thermal dta and tg wet chemical electron microprobe k ar rb sr 40ar 39ar and stable isotope methods with increasing metamorphic grade based on illite crystallinity data xrd and ir the following continuous changes are observed i the 1md 2m1 polymorph transformation is completed in the higher grade anchizone ii k2o increases from 6 8 wt diagenetic zone to 8 5 10 anchizone to 10 11 5 epizone reflecting an increase in the total negative layer charge from 1 2 to 2 0 iii a decrease of the chemical variation of the mica population with detrital muscovite surviving up to the anchizone epizone boundary iv a shift of an endothermic peak in differential thermal curves from 500 to 750 c v k ar and rb sr apparent ages of the fraction 2 m decrease from the diagenetic zone to the epizone k ar ages being generally lower than rb sr ages the critical temperature for total ar resetting is estimated to be 260 30 c k ar and rb sr ages become concordant when the anchizone epizone boundary is approached the stable isotope data on the other hand show no change with metamorphic grade but are dependent on stratigraphic age these results suggest that the prograde evolution from 1 md illite to 2m1 muscovite involves a continuous lattice restructuration without rupture of the tetrahedral and octahedral bonds and change of the hydroxyl radicals however this is not a recrystallization process this restructuration is completed approximately at the anchizone epizone boundary the isotopic data indicate significant diffusive loss of 40ar and 87sr prior to any observable lattice reorganization the restructuration progressively introduces a consistent repartition of ar and k in the mineral lattices and is outlined by the 40ar 39ar age spectra concordant k ar and rb sr ages of around 35 30 ma with concomitant concordant 40ar 39ar release spectra are representative for the main phase of alpine metamorphism calanda phase in the glarus alps a second age group between 25 and 20 ma can probably be attributed to movements along the glarus thrust ruchi phase while values down to 9 ma in regions with higher metamorphic conditions suggest thermal conditions persisting at least until the middle tortonian

dehydration of dioctahedral aluminous phyllosilicates thermodynamic modelling and implications for thermobarometric estimates we propose a solid solution model for dioctahedral aluminous phyllosilicates accounting for the main compositional variations including hydration observed in natural smectites interlayered illite smectite illites and phengites from diagenetic to high grade metamorphic conditions the suggested formalism involves dehydrated micas and hydrated pyrophyllite like thermodynamic end members with these end members the equilibrium conditions of quartz water k bearing mica like phyllosilicates of fixed 2 1 composition are represented by a line in p t space along which the interlayer water content varies the relevant thermodynamic properties required for the calculation of equilibrium conditions were derived using a set of 250 natural data of known maximal temperature and pressure conditions which covers a range between 25 c and few mpa to 800 c and 5 gpa the temperatures calculated at fixed pressure with our model are in fair agreement with those reported in the literature for the 250 natural data at low temperature and pressure the amount of interlayer water in k deficient phengite and illite is predicted to reach 100 of the apparent vacancies which is consistent with previous values reported in the literature although the amount of interlayer water is predicted to decrease with pressure and temperature it is calculated to be significant in k deficient phengite from lt hp pelites metamorphosed at about 350 c 10 kbar the presence of molecular water in the interlayer site of such phengites has been confirmed by ftir mapping its implications for p t estimates are discussed

pre middle jurassic accretionary metamorphism in the southern klamath mountains of northern california usa high p t metamorphic parageneses are preserved within two late palaeozoic to early mesozoic assemblages of the southern klamath mountains that show contrasting structural styles and mineral parageneses reflecting formation in different parts of a subduction zone regime blueschist facies tectonites of the stuart fork terrane represent a coherent subduction complex formed at relatively deep crustal levels whereas the chaotic metasedimentary melange of the eastern hayfork terrane contains a diverse range of metamorphic parageneses reflecting complex structural mixing of metamorphic components at shallower levels the convergent margin type accretionary metamorphism evident in both terranes pre dates middle jurassic low p t metamorphism resulting from regional tectonic contraction and magmatism the epidote to lawsonite zone stuart fork blueschists and eclogites locally formed at pressures of about 6 11 kbar and temperatures of 250 400 c deformed matrix material of the eastern hayfork melange formed at similar temperatures but lower pressures on the order of 3 6 kbar the melange contains a diverse assemblage of tectonic blocks that formed under a range of p t conditions including those of the blueschist pumpellyite actinolite greenschist and upper greenschist to amphibolite facies the succession of mineral parageneses and inferred p t conditions of the eastern hayfork blocks reflect those of igneous protolith formation structural mixing subduction zone metamorphism olistolith transport and tectonic and erosional denudation although temporal relations are not well constrained the evolution of these terranes is consistent with formation within a single convergent margin system

provenance and variscan low grade regional metamorphism recorded in slates from the basement of the sw hungary a metapelitic sequence with silurian protolith from the horvathertelend unit tisza mega unit hungary has a k white mica chlorite quartz albite anatase tourmaline mineral assemblage moderately developed disjunctive and well developed continuous foliations are present geochemical results reflect a dominantly felsic source of the protoliths suggesting an intermediate to acidic volcanic arc in the provenance area metasandstone pebbles in the metaconglomerate indicate a recycled sedimentary source raman spectroscopy of carbonaceous material indicates a 350 370 c peak metamorphic temperature the kubler index kibasel values of the phengitic k white mica indicate epizonal metamorphism 0 22 0 04 2 the chlorite crystallinity index chccis suggests metamorphic alteration near to the anchizone epizone boundary 0 31 0 06 2 k ar ages of k white mica are interpreted as a result of variscan metamorphism c 310 ma and post variscan uplift c 290 ma the predominance of lydite and slate of llandoverian age and the overlying coarse grained metagreywacke and metaconglomerate beds of the szalatnak slate formation show strong lithological similarities with the proximal silurian sequences in the malopolska massif kielce region holy cross mountains poland the original position of the horvathertelend unit is presumably to the northeast from the bohemian massif next to the upper silesian block moravo silesian zone and the malopolska terrane

comparison of diagenetic and low grade metamorphic evolution of chlorite in associated metapelites and metabasites an integrated tem and xrd study chlorite is a common sheet silicate that occurs in various lithologies over a wide grade range involving diagenesis and low grade metamorphism thus the reaction progress of chlorite overs a unique oppor tunity for direct correlation of zonal classification of metasedimentary rocks based on illite crystallinity with metabasite mineral facies to provide such correlation chlorite crystallinity indices apparent mean crystallite sizes and lattice strains crystallite size distributions and compositions of chlorite from coexisting metapelites and metabasites were determined by x ray divraction xrd scanning electron microscopy sem transmission electron microscopy tem analytical electron microscopy aem and electron microprobe emp methods samples were from palaeozoic and mesozoic formations of the bukkium innermost western carpathians hungary that underwent alpine cretaceous orogenic metamorphism metapelites range in grade from late diagenesis to epizone whereas metabasites vary from prehnite pumpellyite through pumpellyite actinolite to greenschist facies despite significant diverences in composition mineral assemblages and textures reaction progress as measured in part by chlorite crystallinity in metapelites paralleled that in metabasites chlorite crystal linity and mean crystallite size increase and the proportion of mixed layers in chlorite decreases whereas the calculated lattice strain does not change significantly with increasing metamorphic grade similar trends but especially at higher grades significant diverences were found in mean crystallite size values using various methods for xrd line profile analyses the increase in crystallite size with increasing grade was demonstrated also by direct tem measurements on ion milled whole rock samples but with a larger scatter of data at higher grades in spite of the diverent kinds of mixed layering in chlorite mg rich smectitic mostly random local corrensite like units in metabasites and fe rich berthierine and diocta hedral smectite in metapelites xrd calculated and tem measured parameters were found to be reliable tools for measuring reaction progress and metamorphic grade of the same degree in both lithotypes

phyllosilicates in very low grade metamorphism transformation to micas phyllosilicates produced mostly by weathering of magmatic metamorphic and sedimentary rocks are widespread in the surficial and near surface zones of the earth s crust these phyllosilicates display very fine grain sizes disordered crystal structures and greatly varying chemical compositions and they represent structurally and chemically metasable phases they are subjected to heat during diagenesis and concomitant metamorphism which provides a long life source of energy for transforming the metastable phases into thermodynamically more stable phases through a long series of partly continuous partly discontinuous reactions the present review summarizes some major mineralogical aspects of these processes with special reference to petrogenetic applications forty years have passed since the first petrogenetic application of the illite structural changes for characterizing diagenetic processes in sedimentary basins weaver 1960 weaver s sharpness ratio as well as kubler s 1964 1968 empirical illite crystallinity index have been easy to use x ray powder diffraction xrd measures of the manifold inter related changes that the hydrous mica like phyllosilicates experience during increasing burial in the first two decades after the introduction of the illite crystallinity concept it was applied to metamorphic petrogenetic studies in certain areas of europe especially to the external fold and thrust belts of the european alps variscides etc these studies were the starting point of important further developments which include awareness of the phyllosilicate transformations during deep burial in sedimentary basins hower et al 1976 inoue et al 1990 amouric and olives 1991 lanson and champion 1991 lindgreen and hansen 1991 eberl 1993 huang et al 1993 whitney and velde 1993 huggett 1995 elliott and matisoff 1996 nieto et al 1996 dong et al 1997 and recognition of the nature of interstratified clay minerals see reynolds and hower 1970 moreover using the theory of powder x ray powder diffraction e g

the palaeogene forearc basin of the eastern alps and western carpathians subduction erosion and basin evolution scarce palaeogene sediment remnants in the eastern alps and western carpathians are interpreted as remains of a continuous forearc basin new apatite fission track geochronological data corroborate mild paleocene eocene exhumation and relief formation in the eastern alps palinspastic restoration and nine palaeogeographical maps of the eastern alps and western carpathians ranging from the paleocene to the late oligocene epoch illustrate west to east migration of subsidence in the forearc basin subsidence isochrons indicate that oblique subduction of the european plate below the adriatic plate was responsible for forearc basin migration at a rate of 8 mm a 1 the periadriatic lineament was formed as a result of shearing by oblique subduction the neogene to recent sumatra forearc basin is an analogue for the evolution of the east alpine west carpathian forearc basin

linking danube river activity to alpine ice sheet fluctuations during the last glacial ca 33 17 ka bp insights into the continental signature of heinrich stadials abstract offshore archives retrieved from marine lacustrine environments receiving sediment from large river systems are valuable quaternary continental records in the present study we reconstruct the danube river activity at the end of the last glacial period based on sedimentological mineralogical and geochemical analyses performed on long piston cores from the north west black sea margin our data suggest that the danube river produced hyperpycnal floods throughout the ca 33 17 ka period four main periods of enhanced danube flood frequency each of 1 5 3 kyr duration are recorded at ca 32 5 30 5 ka equivalent to the first part of heinrich stadial hs 3 at ca 29 27 5 ka equivalent to greenland stadial 4 at ca 25 3 23 8 ka equivalent to hs 2 and at ca 22 3 19 ka based on mineralogical and geochemical data we relate these events to enhanced surface melting of the alpine ice sheet ais that covered 50 000 km2 of the danube watershed at the last glacial maximum lgm our results suggest that i the ais growth from the inner alps to its lgm position in the northern alpine foreland started from ca 30 5 ka ended no later than ca 25 3 ka and was interrupted by a melting episode ca 29 27 5 ka ii the ais volume drastically decreased from ca 22 3 to 19 ka as soon as summer insolation energy at the ais latitude increased and iii hss strongly impacted the ais mass balance through enhanced summer surface melt this together with evidence of severely cool winters and the rapid expansion of sea ice in the north atlantic implies strong seasonality in continental europe during stadials

u th pb geochronology of zircon and monazite from syenite and pincinite xenoliths in pliocene alkali basalts of the intra carpathian back arc basin abstract phreatomagmatic eruptions in the lucenec basin in slovakia ejected fragments of igneous rocks of unknown age and ranging in composition from gabbro to syenite and orthopyroxene granodiorite pincinite two kinds of syenites with different fe3 contents composed of anorthoclase and interstitial metaluminous trachyte to alkali rhyolite glass represent the final products of alkali basalt differentiation at depths of 10 and 15 18 km pincinite composed of plagioclase quartz orthopyroxene ilmenite and interstitial peraluminous dacite glass is a quenched supersolidus anatectic melt formed at the depth of 17 20 km by high temperature dehydration melting of biotite bearing gneissic protolith zircon from pincinite and syenite and monazite from syenite were dated using excimer laser ablation icp ms the obtained ages cluster at 5 8 0 1 and 5 4 0 1 ma thus corroborating the genetic link between the two rock types and constraining the residence time of at least 300 100 ka of the parental basalt in the deep crustal magma storage zones the inferred ages overlap the upper miocene pliocene boundary and are considerably younger than spatially associated basaltic lava flows dated using the k ar method consequently the fluviolacustrine poltar formation overlying the maar structure must have sedimented during the pliocene and not during the upper miocene pontian as previously assumed

phase petrology and p t conditions of mafic blueschists from the meliata unit west carpathians slovakia blueschists occurring as layers in calcite marbles of the meliata unit occur along the so called roznava tectonic line situated in the southern part of the gemericum slovakia mineral assemblages and compositions from seven blueschists localities and one occurrence of amphibolite facies rocks overprinted by blueschist metamorphism were investigated the most common minerals in the blueschists are blue amphibole epidote and albite some fe2 and al rich rocks also contain garnet and chloritoid respectively na pyroxene with a maximum 50 jadeite component was also found the blue amphiboles correspond mostly to crossite and also to glaucophane and ferroglaucophane in some samples almandine and spessartine rich garnet has very low mgo content 3 wt the si content in phengite ranges between 3 3 and 3 5 pfu calculated on the basis of 11 oxygens the zoning patterns of blue amphibole garnet and chloritoid suggest their formation during a prograde stage of metamorphism the p t conditions of metamorphism are estimated to be about 380 460 c and 10 13 kbar pressures of 7 5 8 5 kbar and temperatures of 350 370 c were obtained for some actinolite and aegirine rich rocks apart from chlorite other mafic minerals formed during retrograde metamorphism are biotite and occasionally also actinolite

generation and stability of a quasi permanent vortex in the lofoten basin abstract in the nordic seas the lofoten basin is a region of high mesoscale activity the generation mechanism and the conditions for the stability of a quasi permanent vortex in the center of the lofoten basin are studied with a high resolution ocean circulation model and altimeter data the vortex and its generation mechanism manifest themselves by a pronounced sea surface height ssh signature and variability which are found to be in agreement with altimeter data the vortex results primarily from anticyclonic eddies shed from the eastern branch of the norwegian atlantic current which propagate southwestward the large scale bottom depression of the lofoten basin plays a crucial role for attracting anticyclones into the trough and for enabling the dynamical stability of the vortex the water mass characteristics of the anticyclone lead to enhanced atmospheric interaction heat loss during wintertime the cold water trapped in the upper part of the vortex preconditions convection in the following wi

new cnes cls09 global mean dynamic topography computed from the combination of grace data altimetry and in situ measurements 1 an accurate knowledge of the ocean mean dynamic topography mdt is mandatory for the optimal use of altimetric data including their assimilation into operational ocean forecasting systems a new global 1 4 resolution mdt was computed for the 1993 1999 time period with improved data and methodology compared to the previous rio05 mdt field first a large scale mdt is obtained from the cls01 altimetric mean sea surface and a recent geoid model computed from 4 5 years of grace gravity recovery and climate experiment data altimetric sea level anomalies and in situ measurements are then combined to compute synthetic estimates of the mdt and the corresponding mean currents while the rio05 mdt was based on 10 years of in situ dynamic heights and drifting buoy velocities the new field benefits from an enlarged data set of in situ measurements ranging from 1993 to 2008 and includes all hydrological profiles from the argo array moreover the processing of the in situ data has been updated a new ekman model was developed to extract the geostrophic velocity component from the drifting buoy measurements the handling of hydrologic measurements has also been revisited compared to the previous rio05 solution the new global mdt resolves much stronger gradients in western boundary currents with mean velocities being doubled in some places moreover in comparison to several other recent mdt estimates we find that the new cnes cls09 mdt is in better agreement with independent in situ observations

stratigraphy facies and geodynamic settings of jurassic formations in the bukk mountains north hungary its relations with the other areas of the neotethyan realm jurassic melange complexes related to the subduction of the neotethys ocean occur in the bukk mountains north hungary this paper characterizes the sedimentary sequence of basin and slope facies that occur in the southwestern part of the bukk mountains placing special emphasis on the redeposited sedimentary rocks olistostromes olistoliths monosbel group in order to obtain information on the provenance of the clasts and the mode and time of their redeposition the series of formations studied shows a general coarsening upwards trend based on radiolarians and foraminifera the monosbel group formed in early to late bathonian time the lower part of the complex is typified by a predominance of pelagic carbonates shale and radiolarite with andesitic volcaniclastic intercalations the higher part of the succession is characterized by polymictic olistostromes large olistoliths that are predominantly blocks of bathonian shallow marine limestone bukkzserc limestone appear in the upper part of the sequence based on the biostratigraphic and sedimentological data results of analyses of the redeposited clasts and taking into consideration the concepts of the development of the western neotethys domain the evolutionary stages of the sedimentary basins were defined the onset of the compressional stage led to initiation of nappe stacking that led to the formation of polymict olistostromes and then to the redeposition of large blocks derived from out of sequence nappes of the former platform foreland

evolution of the pannonian basin system 2 subsidence and thermal history analysis of sedimentation and thermal data indicates that for most parts of the pannonian basin observed heat flow thermal gradients rates of thermal subsidence and vitrinite reflectance are about twice those predicted by assuming a uniform extension model for basin formation in late miocene time a modified extension model whereby large amounts of heat are added to the uppermost mantle during extension roughly equivalent to replacing the entire sub crustal lithosphere by asthenosphere produced results in good agreement with observation and could also account for periods of uplift observed during extension crustal extension beneath most parts of the basin is estimated to have been about 80 to 170 1 8 to 2 7 although in the deepest parts of the basin deeper than 4 km crustal extension could have been much greater analysis of extension within the danube and zala basins indicates that the late miocene extension in these basins involved the entire lithosphere but subsidence and heat flow data are not well enough constrained to determine if extra heating is required during extension on the basis of tectonic and structural data the vienna basin has been interpreted as the result of thin skinned extensional tectonics above a shallow detachment surface within the upper crust royden et al this issue analysis of thermal and subsidence data from the northern vienna basin suggests that little or no heating occurred during basin extension these data are consistent with a thin skinned extensional origin for the vienna basin and are in better agreement with this interpretation than with the assumption of a uniformly extended lithosphere beneath the basin this study emphasizes the need for good thermal subsidence and structural data in making reconstructions of extensional and thermal histories of sedimentary basins when such data are available it is found that a simple uniform extension model does not explain very well the evolution of some sedimentary basins such as the vienna and pannonian basins in the first instance the basin is thought to be the result of upper crustal extension only due to its special tectonic setting in the second instance the extra heating during extension is due to some unknown processes in the lower lithosphere that may be a general feature of lithospheric extension thus lithospheric extension and associated heating may be distributed in a variety of ways not all extensional sedimentary basins form in the same way application of a uniform subsidence model to basins for which good thermal subsidence and structural data are not available or not properly analysed can lead to reconstructions of thermal histories in error by a factor of 2 or more

baroclinic instability and the mesoscale eddy field around the lofoten basin the vigorous mesoscale eddy field around the lofoten basin west of northern norway is thought to be related to eddy shedding from the norwegian atlantic current flowing along the norwegian coast here we study baroclinic instability in the current with a particular focus on the influence of topography the flow over the steepest part of the continental slope is found to be the most unstable the growth characteristics cannot be understood from eady theory alone but require the consideration of interior potential vorticity gradients a study of the fully developed macroturbulent field shows that eddy kinetic energy is advected away from the generation regions and that nonlinear effects likely draw the eddy statistics away from the linear growth regime

u pb geochronology of zircons from fossiliferous sediments of the hajnacka i maar slovakia type locality of the mn 16a biostratigraphic subzone lacustrine sediments of the hajnacka i maar of southern slovakia contain teeth and skeletal remains of a mammal fauna including index early villanyian arvicoline rodents u pb dating of magmatic zircons extracted from the redeposited fossiliferous maar sediments revealed a total of six volcanic events the oldest age of 3 43 ma was interpreted as that corresponding to the initial phreato magmatic eruption that created the maar most zircons grouped around 3 06 0 03 ma the age attributed to the catastrophic eruption that killed the mammal assemblage thriving within and around the maar studied this age coincides with the 3 1 ma boundary between the mn 16a and 16b subzones of the european mammal neogene chronostratigraphic scale estimated from the succession of early villanyian palaeontological localities according to the hypsometry of rodent teeth younger zircon ages overlapped those of the neighbouring basaltic lava flows necks and dykes thus recording superimposed effusions the youngest 1 58 ma old zircon defines the age limit for the final redeposition of the fossiliferous sediments in the maar drainage lake regime

use of the lattice parameter b 0 of dioctahedral illite muscovite for the characterization of p t gradients of incipient metamorphism the p t gradient or baric type of low grade metamorphic terranes can be characterized on the basis of cumulative frequency curves of the lattice parameter b0 of dioctahedral micas sassi and scolari 1974 which essentially reflects celadonite content and increases with pressure the method is here applied to illite muscovite of sub greenschist incipient metamorphism and low greenschist facies terranes from the marginal zones of the swedish caledonides swiss alps and venezuelan andes where the grade of metamorphism was determined on the basis of illite crystallinity

wind driven variability of the large scale recirculating flow in the nordic seas and arctic ocean the varying depth integrated currents in the nordic seas and arctic ocean are modeled using an integral equation derived from the shallow water equations this equation assumes that mass divergence in the surface ekman layer is balanced by convergence in the bottom ekman layer the primary flow component follows contours of f h the model employs observed winds and realistic bottom topography and has one free parameter the coefficient of the linear bottom drag the data used for comparison are derived from in situ current meters satellite altimetry and a primitive equation model the current meter data come from a 4 yr record at 75 8 ni n the greenland sea the currents here are primarily barotropic and the model does well at simulating the variability the best bottom friction parameter corresponds to a spindown time of 30 60 days a further comparison with bottom currents from a mooring on the norwegian continental slope deployed over one winter period also shows reasonable correspondence the principal empirical orthogonal function obtained from satellite altimetry data in the nordic seas has a spatial structure that closely resembles f h a direct comparison of this mode s fluctuations with those predicted by the theoretical model yields linear correlation coefficients in the range 0 75 0 85 the primitive equation model is a coupled ocean ice version of the princeton ocean model for the north atlantic and arctic monthly mean depth averaged velocities are calculated from a 42 yr integration and then compared with velocities predicted from an idealized model driven by the same reanalyzed atmospheric winds in the largely ice free norwegian sea the coherences between the primitive equation and idealized model velocities are as high as 0 9 on timescales of a few months to a few years they are lower in the remaining partially or fully ice covered basins of the greenland sea and the arctic ocean presumably because ice alters the momentum transferred to the ocean by the wind the coherence in the canadian basin of the arctic can be increased substantially by forcing the idealized model with ice velocities rather than the wind estimates of the depth integrated vorticity budget in the primitive equation model suggest that bottom friction is important but that lateral diffusion is of equal or greater importance in compensating surface ekman pumping

long term fluid circulation in extensional faults in the central catalan coastal ranges p t constraints from neoformed chlorite and k white mica the neoformation of chlorite and k white mica in fault rocks from two main faults of the central catalan coastal ranges the valles and the hospital faults has allowed us to constrain the p t conditions during fault evolution using thermodynamic modeling crystallization of m1 and m2 muscovite and microcline occured as result of deuteric alteration during the exhumation of the pluton 290 c t 370 c in the permian after that three tectonic events have been distinguished the first tectonic event attributed to the mesozoic rifting is characterized by precipitation of m3 and m4 phengite together with chlorite and calcite c1 at temperatures between 190 and 310 c the second tectonic event attributed to the paleogene compression has only been identified in the hospital fault with precipitation of low temperature calcite c2 the shortcut produced during inversion of the valles fault was probably the responsible for the lack of neoformed minerals within this fault finally the third tectonic event which is related to the neogene extension is characterized in the valles fault by a new generation of chlorite associated with calcite c4 and laumontite formed at temperatures between 125 and 190 c in the absence of k white mica differently the hospital fault is characterized by the precipitation of calcite c3 during the syn rift stage at temperatures around 150 c and by low temperature fluids precipitating calcites c5 c6 and pc1 during the post rift stage during the two extensional events mesozoic and neogene faults acted as conduits for hot fluids producing anomalous high geothermal gradients 50 c km minimum

40ar 39ar dating of the inner carpathians variscan basement and alpine mylonitic overprinting abstract the 40ar 39ar dating method has been applied to mylonitic rocks from the carpathian mountains these are variscan metamorphic and magmatic rocks that were overprinted during the alpine orogeny the inner western carpathians are conventionally described as a nappe pile formed by northward movement and then subjected to intense strike slip and normal faulting resulting in the formation of mylonitic rocks precise stratigraphie ages provide clear constraints for the geodynamic interpretation related to the succession of alpine events such as the pre gosauian phase during the turonian 90 ma the 40ar 39ar method allows to define the age of the ancient variscan basement and the ages of the alpine overprinting in the high and low tatras mineral ages of around 340 350 ma are yielded by gneisses micaschists and amphibolites providing a younger limit for the variscan metamorphism the emplacement cooling of the variscan granites is defined between 305 and 335 ma these rocks are overprinted by several alpine tectonothermal events the major events are dated at 65 and 86 88 ma during which the mylonites were generated an older event around 140 ma earlier defined by the rb sr method is now confirmed by the 40ar 39ar method dating of phengites extracted from high pressure metamorphic triassic rocks from the kosice area yields new data for the age of this event at 155 ma