origin of siderite veins in the western carpathians abstract siderite barite veins of the rud any ore field have precipitated from nacl cacl 2 h 2 o co 2 solutions with cacl 2 weight fractions between 0 05 and 0 38 total salinities between 17 and 35 wt and up to 1 8 mol co 2 homogeneous and heterogeneous trapping modes have been distinguished according to volumetric phase ratios of the fluid inclusions which have been trapped at 175 205 c in veiny siderite at 200 230 c in siderite and quartz from drusy cavities and at 90 180 c in the siderite postdating quartz sulfidic assemblage a sequential re equilibration technique has been developed to locate precisely vapour saturated halite liquidus of individual brine inclusions which normally homogenise by halite dissolution slopes of the vapour unsaturated halite liquidi constrained by isochores of coexisting two phase aqueous inclusions have been approximately three to five times steeper in natural polycomponent brines than those in the experimental nacl h 2 o system fluid pressures between 1 and 2 kbar have been determined using this method in drusy quartz associating with siderite crystals oxygen isotope variations 16 8 19 9 v smow in siderite result from a temperature increase from 175 to 230 c whereas nearly constant 13 c values 3 9 to 4 6 v pdb indicate absence of co 2 devolatilisation carbon isotope composition of the parental fluid changed from 9 5 to 8 8 v pdb while the oxygen isotope ratios remained essentially fixed at 7 7 0 3 v smov during formation of siderite the calculated 18 o fluid value is attributed to formation water enriched in 18 o during isotopic exchange with crustal rocks at low fluid rock ratios the 13 c fluid values probably correspond to a mixture of co 2 from dissolved matrix carbonates and that liberated by thermal decarboxylation of organic acids acetates which normally occur in formation waters leachate chemistry data have corroborated high concentrations of cacl 2 and mgcl 2 in the ore forming brines high br concentrations are similar to halite fractionated basinal brines ca 2 and k concentrations in excess of those in normal basinal brines reflect extensive cation exchange with surrounding low to medium grade metamorphites coincidental with calcite and k feldspar dissolution dolomitisation and albitisation of plagioclases high pressures of the siderite forming fluids 1 2 kbar must be linked with a deep circulation 4 8 km of the basinal brines derived primarily from marine water but significantly modified by interaction with low to medium grade paleozoic rocks at low fluid to rock ratios an anti clockwise crystallisation pt path inferred from fluid inclusion and stable isotope data is inconsistent with the siderite precipitation during extensional tectonic regime coincidental with permian triassic rifting suggested in previous models more likely the progressively increasing fluid pressures and temperatures could be attributed to compression and crustal thickening triggered by jurassic subduction in the meliatic hallstatt oceanic suture the superimposed quartz ankerite sulfidic ores have likely crystallised from brines expelled during compression associated with a continental collision during early to middle cretaceous times

how many oceans meliata vardar and pindos oceans in mesozoic alpine paleogeography the timing of rifting and subduction in the meliata vardar and pindos zones of the hellenic dinaric carpathian region indicates that they cannot be considered remnants of a single ocean basin in contrast to several recently published mesozoic paleogeographies sea floor spreading in the meliata zone culminated in middle triassic ladinian time and ceased in the late triassic and subduction occurred from this time until late jurassic closure in contrast sea floor spreading in the vardar zone began in early jurassic time and culminated in the middle jurassic and subduction occurred from latest jurassic time in the pindos zone sea floor spreading was initiated in the early triassic with late jurassic and early tertiary subduction

regional setting and geochronology of the late cretaceous banatitic magmatic and metallogenetic belt the 1 500 km long banatitic magmatic and metallogenetic belt bmmb of romania serbia and bulgaria is a complex calc alkaline magmatic arc of late cretaceous age it hosts a variety of magmatic hydro thermal cu au mo zn pb and fe deposits including europe s only world class porphyry copper deposits regional metallogeny can be linked to subduction of the vardar ocean during the late cretaceous as part of the closure of the neotethys ocean that had separated europe and africa in the mesozoic porphyry cu au mo and intimately associated epithermal massive sul phides dominate in the central segments of the belt in southernmost banat romania serbia and north west bulgaria these districts are the economically most im portant today including major active cu au mines at moldova noua in romania majdanpek veliki krivelj and bor in serbia and elatsite assarel and chelopech in bulgaria more numerous and mostly mined in the past are fe cu and zn pb skarns which occur mainly at the two ends of the belt in eastern bulgaria and in romania this paper summarises some of the deposit characteristics within the geodynamic framework of terminal vardar subduction heterogeneous terranes of the belt including the apuseni mountains at the western end are aligned parallel to the vardar front following continental collision of the dacia and tisza blocks all available geochronological data numerous k ar and some u pb and re os ages are compiled and are complemented by a new high precision re os date for the dognecea skarn deposit south west romania 76 6 0 3 ma these data indicate that magmatism extended over at least 25 million years from about 90 to 65 ma in each segment of the belt within apuseni mountains and banat where magma emplacement was related to syn collisional extension in the orogenic belt of carpathians ore formation seems to be restricted in time and maybe constrained by a shared tectonic event

reply to allen et al s comments on on magma fragmentation by conduit shear stress evidence from the kos plateau tuff aegean volcanic arc by palladino simei and kyriakopoulos jvgr 2008 178 807 817

provenance of tin in the late bronze age balkans based on probabilistic and spatial analysis of sn isotopes abstract we report the largest published dataset to date of sn isotopic compositions of bronze age artifacts 338 along with 150 cassiterite samples 75 new from six potential tin ore sources from which the tin in these artifacts were thought to have likely originated the artifacts are from a broad area central europe through the central balkans and the six tin sources are cornwall three sites in the erzgebirge and two sites in serbia a clustering analysis on mean site level isotopic values of 124sn identifies regional variation that can be attributed to the use of different tin ore sources in different regions therefore geographically meaningful regions were identified to group the bronze age artifact assemblages and a probabilistic bayesian analysis was performed to determine the proportional contribution of each tin source to each regional assemblage artifacts enriched in heavy isotopes 124sn 0 7 that cluster in west central serbia are likely associated with the ores from mt cer in west serbia mixed artifact assemblages high and low 124sn in this region are attributed to the use of cassiterite from the two serbian sites mt cer and mt bukulja moderate composition artifacts that occur north of the middle danube in vojvodina transylvania and central europe are likely associated primarily with ores from the west pluton of the erzgebirge compositionally light bronzes 124sn

slab breakoff a model for syncollisional magmatism and tectonics in the alps slab breakoff is the buoyancy driven detachment of subducted oceanic lithosphere from the light continental lithosphere that follows it during continental collision in a recent paper davies and von blanckenburg 1994 have assessed the physical conditions leading to breakoff by quantitative thermomechanical modeling and have predicted various consequences in the evolution of mountain belts breakoff will lead to heating of the overriding lithospheric mantle by upwelling asthenosphere melting of its enriched layers and thus to bimodal magmatism breakoff will also lead to thermal weakening of the subducted crustal lithosphere thereby allowing buoyant rise of released crustal slices from mantle depths in this paper we present a test of this model in the tertiary evolution of the european alps in the alps both basaltic and granitoid magmatism occur between 42 and 25 ma following the closure of oceanic basins by subduction and continental collision the granitoids are now well established to result from mixing of basalt with assimilated continental crust to identify the tectonically crucial origin of the partial mantle melts we have compiled all published geochemical and isotopic data of numerous mafic dykes occurring throughout the whole alpine arc their trace element and isotopic composition suggests that they have been formed by low degree melting of the mechanically stable lithospheric mantle we see no evidence for melting of asthenospheric mantle it was thus not decompressed to depths shallower than 50 km once initiated rapid lateral migration of slab breakoff will result in a linear trace of magmatism in locally thermal weakened crust this explains why all alpine magmatic rocks intruded almost synchronously along a strike slip fault the periadriatic lineament a compilation of ages from penninic high pressure rocks subducted to depths of up to 100 km shows that subduction took place at circa 55 40 ma followed by uplift at 40 35 ma from the short time interval between their uplift and the onset of magmatism we infer that both processes have been induced by the breakoff the slab breakoff model fulfills its predictions in the case of the alps and therefore supports the assumptions made in the theoretical model on a geological basis we believe that the characteristic association of magmatic activity with the return of high pressure rocks to the surface allows the identification of this process in the earth s mountain belts

provenance of intermediate waters in the western north pacific deduced from thermodynamic imprint on δ13c of dic 1 stable carbon isotopes of dissolved inorganic carbon 13cdic together with phosphate concentrations po43 of the western north pacific marginal area are presented although 13cdic controlled not only air sea exchange but also biological activities by subtracting po43 as a biological factor from the 13cdic the thermodynamic imprint on the carbon isotopic composition 13cas is used as a conservative tracer the linear relationship between 13cas and temperature with the 13cas temperature slope of 0 104 c is observed in the north pacific subtropical region this relationship can be extended to the weddell sea deep waters therefore oceanic dic is apparently in temperature dependent isotopic equilibrium with atmospheric co2 to characterize each water mass the isotopically labeled temperature tiso which is derived from 13cas temperature relationship obtained for the subtropical gyre water and weddell sea water is introduced in contrast the 13cas temperature relationship is not necessarily linear for the northern japan sea water the kuroshio oyashio mixed water and the okhotsk sea water this nonlinearity implies apparent air sea carbon isotopic disequilibria resulting from water cooling without accompanying air sea carbon isotope equilibrium by using the potential temperature tpot and the tiso the source waters constituting intermediate waters 26 8 have been estimated the results clearly indicate that 1 the intermediate water in the southern okhotsk sea contains up to 20 japan sea water and that 2 new north pacific intermediate water npiw consists of okhotsk sea water subarctic gyre water and old subtropical npiw

metallogeny of the northwestern and central dinarides and southern tisia abstract the dinaridic metallogenic province is a part of the alpine himalayan orogenic system developed as a result of opening and closure of the tethys ocean by convergence of the african and eurasian plates the northern boundary of the dinarides is related to the northern african margin adria apulia the tisia mega unit a small continental block positioned between the dinarides and the carpathians is genetically related to the south eurasian edge the geology of the dinarides is constrained by the alpine wilson cycle the major stages of the cycle are a permian early intra continental rifting b triassic advanced rifting c jurassic oceanization d cretaceous subduction e paleogene collision and f neogene post collision and extension followed by orogenic collapse each stage creates characteristic ore deposits related to the specific geological environments stage a bears hydrothermal siderite barite polysulphide deposits epigenetic sedimentary uranium deposits red bed type sabkha type copper and barite deposits and evaporites stage b favored sedex and hydrothermal iron polysulphide barite mercury and mvt deposits stage c developed chromites asbestos talc and magnesite deposits the spatial position of stage d remains poorly constrained the southern tisia unit might be a possible candidate for the tethyan active continental margin with the cretaceous subduction zone positioned beneath absence of voluminous subduction related magmatism and mineral deposits however favors subduction within the vardar zone the easternmost dinarides adjoined to the serbomacedonian ensialic terrain with its large cu porphyry deposits stage e was a prelude to the prolific phase f with its numerous hydrothermal pb zn and sb deposits that mostly occur in the western vardar zone the geology and metallogeny of southern tisia with medium high grade metamorphics i type s type granites resembles the middle austro alpine unit formed during the main carboniferous collisional stage this contribution provides a review of the metallogenic characteristics of the northwestern and central dinarides and southern tisia mega units based on recently gained knowledge on the regional geology petrology and genesis of mineral deposits establishment of the plate tectonic model several decades ago greatly contributed to an integrated interpretation of ore deposit genesis in turn basic research in the field of ore genesis generated new data that can be used to improve the plate tectonic model

ore deposits of the french massif central insight into the metallogenesis of the variscan collision belt the french massif central fmc represents the whole west european variscan wev belt in terms of both the geodynamic evolution and the metallic content thus a study of the metallogenic evolution of the fmc may elucidate the conditions that allow the mineralisation of a collision belt since recent collision belts e g the himalayas or the alps show that mineralisation does not necessarily result from the collision process the palaeozoic history of the fmc is divided into three geodynamic stages unevenly involved from the metallogenic view point the eo variscan stage cambrian to silurian was not important the meso variscan stage devonian early carboniferous was of limited importance and most of the mineralisations formed during the neo variscan stage late carboniferous early permian in addition some more mineralisation was produced during the mesozoic because of the thermal reactivation linked with the alpine orogenies

paleozoic tectonostratigraphic units of the northwest and central dinarides and the adjoining south tisia in the central dinarides and south tisia different paleozoic complexes occur in four geotectonic zones 1 comparatively autochthonous units located in the cores of disrupted anticlines of the external dinarides 2 allochthonous disrupted units accompanied by more predominant triassic formations in the sava nappe which is thrust onto the northeastern margin of the external dinarides 3 allochthonous disrupted units also together with triassic formations in the pannonian and durmitor nappes of the internal dinarides and 4 polymetamorphic sequences in basement of the pannonian basin and south tisia respectively this paper presents basic geological features for the main paleozoic areas included in these four zones the tectonostratigraphic units of the first two zones were related to the gondwana passive continental margin those of the third zone to the paleotethyan oceanic realm and those of tisia to the active laurussia margin geodynamic evolution of all these paleozoic complexes was related to opening and closure of the rheic and paleotethys oceans rifting processes along north gondwana started in the silurian locally in the cambrian ordovician and were followed by the late silurian devonian opening of the paleotethys subduction processes were active by the end of the devonian and at the beginning of the carboniferous along the laurussia margin they were followed during the westphalian by main variscan deformation during collision of gondwana and laurussia associated metamorphism was very low grade in the paleozoic units of the sava nappe low grade to epidote amphibolite grade within the paleozoic complexes of the pannonian and durmitor nappes in the internal dinarides and poly metamorphic with migmatites and granitoids in south tisia these processes gave rise to a pangea stage with the variscan basement disconformably overlain by late carboniferous and permian sediments

microbially mediated iron ore formation silicic superunit rudabanya hungary abstract the mineralogical petrological geochemical and textural characterization of the triassic bodvaszilas sandstone in the rudabanya open pit and aggtelek mts is summarized based on our investigations the pore filling carbonate cement in the lower triassic bodvaszilas sandstone formation of a proximal basin series rudabanya was formed as the result of syngenetic and early diagenetic two step microbially mediated fe mineralization fe oxide formation by chemo lithoautotrophic fe oxidizing microbes feob in a suboxic neutrophylic environment and fe carbonate by heterotrophic microbes in a suboxic to anaerobic environment based on mineralized microbially produced textural evidences the carbonate in the higher parts of the formation transition between the bodvaszilas sandstone and the overlying formation szin marl was formed by the same metasomatic processes that produced the siderite ore in the middle triassic limestones and dolomites these processes led to partial or complete fe replacement of the syngenetic carbonate layers microbially mediated fe enrichment also occurred at distal basin position in the bodvaszilas sandstone aggtelek mts the formation later underwent deep burial diagenesis

accretionary history and crustal evolution of the variscan belt in western europe abstract the variscan belt of western europe is part of a large intra paleozoic belt extending on both sides of the atlantic from the ouachitas in the us and the mauritanides in west africa to the bohemian massif in czechoslovakia and poland the belt was constructed between 500 and 250 ma as a result of convergence and collision between two main continents laurentia baltica and africa after the closure of various oceanic basins iapetus rheic and galicia massif central now recorded as discrete in part cryptic sutures which form the roots of large crystalline nappes in which are found dismembered remnants of oceanic crust and mantle the accretionary history of the variscan belt in western europe is related to the progressive closure of probably two oceanic basins the rheic in the north and another the galicia massif central in the south by respectively southward and northward intraoceanic subduction followed by obduction and intracontinental lithospheric subduction the result is a broad 700 800 km fan like divergent belt which must be considered as a classical obduction collision orogen with a long intracontinental history of about 100 150 ma its arcuate shape is probably due to the northwestward impingement of a promontory of the african continent into laurentia baltica

metallogenic model of the trepca pb zn ag skarn deposit kosovo evidence from fluid inclusions rare earth elements and stable isotope data the trepca pb zn ag skarn deposit 29 mt of ore at 3 45 pb 2 30 zn and 80 g t ag is located in the kopaonik block of the western vardar zone kosovo the mineralization hosted by recrystallized limestone of upper triassic age was structurally and lithologically controlled ore deposition is spatially and temporally related with the postcollisional magmatism of oligocene age 23 26 ma the deposit was formed during two distinct mineralization stages an early prograde closed system and a later retrograde open system stage the prograde mineralization consisting mainly of pyroxenes hd54 100jo0 45di0 45 resulted from the interac tion of magmatic fluids associated with oligocene 23 26 ma postcollisional magmatism whereas there is no direct contact between magmatic rocks and the mineralization the deposit is classified as a distal pb zn ag skarn abundant pyroxene reflects low oxygen fugacity 10 31 bar and anhydrous environment fluid inclu sion data and mineral assemblage limit the prograde stage within a temperature range between 390 and 475 c formation pressure is estimated below 900 bars isotopic composition of aqueous fluid inclusions hosted by hedenbergite d 108 to 130 18o 7 5 8 0 mn enriched mineralogy and high ree content of the host carbonates at the contact with the skarn mineralization suggest that a magmatic fluid was modified during its infiltration through the country rocks the retrograde mineral assemblage comprises ilvaite magnetite arsenopyrite pyrrhotite marcasite pyrite quartz and various carbonates increases in oxygen and sulfur fugacities as well as a hydrous character of min eralization require an open system model the opening of the system is related to phreatomagmatic explosion and formation of the breccia arsenopyrite geothermometer limits the retrograde stage within the temperature range between 350 and 380 c and sulfur fugacity between 10 8 8 and 10 7 2 bars the principal ore minerals galena sphalerite pyrite and minor chalcopyrite were deposited from a mod erately saline ca na chloride fluid at around 350 c according to the isotopic composition of fluid inclusions hosted by sphalerite d 55 to 74 18o 9 6 to 13 6 the fluid responsible for ore deposition was dominantly meteoric in origin the 34s values of the sulfides spanning between 5 5 and 10 point to a magmatic origin of sulfur ore deposition appears to have been largely contemporaneous with the retrograde stage of the skarn development postore stage accompanied the precipitation of significant amount of carbonates including the travertine deposits at the deposit surface mineralogical composition of travertine varies from calcite to siderite and all carbonates contain significant amounts of mn decreased formation temperature and depletion in the ree content point to an influence of ph neutralized cold ground water and dying magmatic system

volcanic facies analysis of a subaqueous basalt lava flow complex at hruskovec nw croatia evidence of advanced rifting in the tethyan domain abstract the hruskovec quarry of basaltoid rocks is situated on the northwestern slopes of mt kalnik within the zagorje mid transdanubian zone a part of the north western dinarides the basaltoids are inter bedded with radiolarites of the middle and upper triassic age langobardian carnian norian spilites altered diabases and meta basalts form part of triassic volcanic sedimentary sequence made of sandstones shales micritic limestone altered vitric tuffs and radiolarian cherts incorporated tectonically into the jurassic cretaceous melange the architecture of the 2 km long and 100 m high pile of the extrusive basaltoid rocks is interpreted as a subaqueous basaltic lava flow the presented research deals with a variety of volcanic facies of the subaqueous basaltic lava flow which consists of several facial units 1 coherent pillow lavas with massive core the bending rims around the massive core 30 50 cm thick are dissected by polygonal columnar joints radiating from the pillow centres 2 closely packed pillows densely packed and contorted pillows due to emplacement accommodation clearly younging upward 3 pillow fragment breccia clast supported matrix poor monomict breccia formed proximal to the axis of the extrusion 4 isolated pillow breccia matrix supported clast poor breccia made of lava pipes and tubes within a matrix of fine grained sideromelan granules and shards 5 pyjama style pillows spherical decimetre to meter size pillow lava balls grown and chilled in isostatic state i e in a state of diminished density contrast within water soaked sediments named after peculiar alternating basaltic shelves inside the sphere which are encrusted with white secondary minerals 6 peperite and peperitic hyaloclastites blocky and globular peperites developed at the contact of soft wet sediment and hot intruding magma discovery of peperite and peperitic hyaloclastites within the triassic radiolarian cherts shales and micritic limestone with registration of conodonts index microfossils links their origin to magmatism during advanced rifting in a progressively subsiding basin during the triassic it precludes an affiliation of the subaqueous basaltic lava flow with the dismembered ophiolite formation a product of oceanization created in jurassic cretaceous times which is a commonly stated alternative explanation the basaltic rocks and their sedimentary hosts may be correlated with advanced triassic rifting and related volcanic sedimentary successions in the dinarides albanides helenides and further along the tethyan orogenic belt

triassic magmatism of the dinarides in yugoslavia abstract the triassic magmatism of the dinarides had a polyphase character it took place during a period of about 50 ma during the initial stages of the mesozoic wilson cycle their earliest phases might have been connected with rifting processes and the subsequent ones preceeded directly the opening of the dinaridic part of the tethys and the formation of a spreading ridge the triassic magmatism is represented by basic and more commonly by intermediate and acid plutonic and volcanic rocks with calc alkaline affinity the triassic magmatic rock association can be correlated on major element evidence with calc alkaline rocks of recent convergent plate margins however field relationships and the data on immobile trace elements indicate that lavas poured out over triassic sediments on a carbonate platform which was underlain by rocks of the continental crust the basic diversity of the triassic magmatism of the dinarides was influenced by partial melting other processes crystallization contamination and others must have played a secondary role

the carpatho balkanides and adjacent area a sector of the tethyan eurasian metallogenic belt the tethyan eurasian metallogenic belt temb was formed during mesozoic and post mesozoic times in the area of the former tethyan ocean on the southern margin of eurasia with the afro arabian and indian plates to the south it extends from western mediterranean via the alps and southeastern europe through the lesser caucasus the hindu kush and the tibet plateau to burma and sw indonesia linking with the west pacific metallogenic belt the carpatho balkan region is one of the sectors of the temb characterized by some specific features the emplacement of ore deposits is related to a definite time interval and to specific tectonic settings such as

geodynamic evolution of the central dinarides abstract the central part of the dinarides unlike the northwestern and southeastern dinarides shows a consistent pattern in the distribution of the large tectonostratigraphic units from southwest apulia to northeast the following five main units originating in different parts of the mesozoic tethys can be distinguished 1 adriatic dinaridic carbonate platform formations 2 carbonate clastic units flysch bosniaque of the passive continental margin 3 ophiolite bearing formations of the dinaridic ophiolite zone also containing radiolarites greywackes and shales including melange formations and overstepped late jurassic to cretaceous cover sequences 4 active continental margin units represented by upper cretaceous palaeogene trench sediments with blueschists tectonized ophiolite melange alpine medium pressure metamorphic rocks originated from upper cretaceous palaeogene sediments and alpine synkinematic granitoids 5 a nappe consisting of allochthonous palaeozoic triassic formations which is thrust onto the ophiolites and genetically related sedimentary formations the frontal parts of this nappe directly overlie the northeastern margin of the adriatic dinaridic carbonate platform i e the external dinarides the evolution of the central dinarides was controlled by a sequence of tectonic events which took place within the alpine cycle 1 rifting processes lasting some 40 50 ma which started in the late permian and ended in the norian 2 opening of the oceanic dinaridic tethys commenced in the late triassic and persisted for some 70 80 ma until the end of the jurassic 3 subduction processes and emplacement of ophiolites started in late jurassic early cretaceous times during the closing phase of the dinaridic ocean or dinaridic tethys the palaeozoic triassic nappe was emplaced on the ophiolites the thrusting was accompanied by alpine metamorphism 120 100 ma 4 the main alpine deformational event and medium pressure metamorphism with synkinematic granite plutonism took place in late eocene early oligocene times when the ophiolite and palaeozoic triassic nappes were emplaced on the adriatic dinaridic carbonate platform which at the same time was deformed resulting in the development of the external dinarides fold and thrust belt

volcaniclastic aggradation in a semiarid environment northwestern vulcano island italy most studies of volcaniclastic facies and aggradation cycles have been conducted in regions with humid climates and on regional scales here we document a volcaniclastic succession that formed in a semiarid climate characterized by rare heavy rains onto a relatively barren volcanic landscape on vulcano island italy the deposits which we informally call the cuesta succession occur in a small valley between two rhyolite domes and consist of a sequence of pyroclastic surge and fallout deposits interbedded with their reworked equivalents a phase of eruptive activity characterized by sporadic hydrovolcanic explosions supplied ash to the valley and its flanks runoff events during the eruptive phase continually washed ash down to the valley floor in the form of hyperconcentrated flows the inferred transport mechanism and depositional facies of these beds reflect the control of primary volcanic fragmentation processes on sedimentation the abundant medium to coarse ash supplied by eruption was incorporated sufficiently easily into the runoff to hyperconcentrate the flows but not sufficiently fine grained to make the flows cohesive these flows moved out onto the floor merged and transported ash down the valley axis depositing the ash as a monotonous succession of massive to faintly laminated beds the combination of primary deposits and the deposits washed off the valley flanks led to aggradation of the valley floor as eruptions waned ash was eroded off the flanks faster than it was replenished leading to a stratigraphic upward increase in lithic clasts derived from the underlying lavas and a wider range of sedimentary facies as the ash load became more variable after eruptions ceased and all remaining ash was removed from the flanks aggradation gave way to degradation to form small canyons that expose the succession

tectonothermal evolution of the apuseni mountains romania resolution of variscan versus alpine events with 40ar 39ar ages abstract polyphase alpine transcurrent faulting and thrusting in the apuseni mountains in romania resulted in the juxtaposition of contrasting structural units that include both metamorphic assemblages and permian mesozoic cover resolution of the chronology of alpine events and distinction from pre alpine evolution has been possible by systematic 40ar 39ar mineral dating of medium and low grade assemblages hornblende and muscovite within nonretrogressed northern sectors of the somes gneissic assemblage record rapid postmetamorphic cooling between 317 and 300 ma following a regionally penetrative late variscan tectonothermal overprint the codru amphibolite granodiorite assemblage records markedly older 40ar 39ar mineral ages 400 365 ma hornblende 340 335 ma muscovite that date delayed postmetamorphic cooling following early variscan tectonothermal activity although variably overprinted during mesozoic tectonism late variscan tectonothermal activity 320 300 ma is also evident from analysis

comments on on magma fragmentation by conduit shear stress evidence from the kos plateau tuff aegean volcanic arc by palladino simei and kyriakopoulos jvgr 2008 178 807 817

mesozoic plate tectonic reconstruction of the carpathian region abstract palaeomagnetic palaeobiogeographic and structural comparisons of different parts of the alpine carpathian region suggest that four terranes comprise this area the alcapa tisza dacia and adria terranes these terranes are composed of different mesozoic continental and oceanic fragments that were each assembled during a complex late jurassic cretaceous palaeogene history palaeomagnetic and tectonic data suggest that the carpathians are built up by two major oroclinal bends the alcapa bend has the meliata oceanic unit correlated with the dinaric vardar ophiolite in its core it is composed of the western carpathians eastern alps and southern alcapa units transdanubian range bukk this terrane finds its continuation in the high karst margin of the dinarides further elements of the alcapa terrane are thought to be derived from collided microcontinents czorsztyn in the n and a carbonate unit tisza in the se the tisza dacia bend has the vardar oceanic unit in its core it is composed of the bihor and getic microcontinents this terrane finds its continuation in the serbo macedonian massif of the balkans the bihor getic microcontinent originally laid east of the western carpathians and filled the present carpathian embayment in the late palaeozoic early mesozoic the vardar ocean occupied an intermediate position between the western carpathian austroalpine transdanubian high karst margin and the bihor getic serbo macedonian microcontinent the vardar and pindos oceans were opened in the heart of the mediterranean adriatic microcontinent in the late permian middle triassic vardar subducted by the end of jurassic causing the bihor getic serbo macedonian microcontinent to collide with the internal dinaric western carpathian margin an external penninic vahic ocean tract began opening in the early jurassic separating the austroalpine western carpathian microcontinent and its fauna from the european shelf further east the severin ceahlau magura also began opening in the early jurassic but final separation of the bihor getic ribbon and its fauna from the european shelf did not take place until the late middle jurassic the alcapa and the tisza dacia were bending during the albian maastrichtian the two oroclinal bends were finally opposed and pushed into the gates of the carpathian embayment during the palaeogene and neogene at that time the main n s shortening in distant alpine and hellenic sectors was linked by a broader right lateral shear zone along the former vardar suture

upper and middle crustal response to delamination an example from the lachlan fold belt eastern australia a delamination model applied to the lachlan fold belt in eastern australia shows that lithospheric delamination began in the early silurian 430 ma after crustal thickening in the wagga omeo zone the delamination induced isostatic uplift farther east to produce localized transient extensional basins and coeval silicic magmas which formed by partial melting of the lower crust during asthenospheric upwelling however the voluminous granitoid intrusions were emplaced during and after compression reflecting reestablishment of horizontal compression associated with plate convergence continued sinking of the slab produced an east ward widening orogenic belt where the granite batholiths and associated thermally softened zones of deformation tracked the direction of delamination once the slab was completely detached at 400 ma the compressive stresses were transmitted across the belt and delamination recommenced about 1000 km westward against the cratonic margin the process was repeated at 400 370 ma within 60 m y the two sinking slabs had converted a 1700 2000 km wide continental margin into a 700 km wide orogenic belt important effects of delamination on the upper and middle crust are 1 production of regional scale low pressure metamorphic belts of limited crustal thickness 2 widespread voluminous silicic magmatism 3 lack of deep crustal exposures even with high degrees of crustal shortening and 4 partial replacement of the lower crust by a mafic underplate that cooled completely after deformation ceased

lateral variations within coarse co ignimbrite lithic breccias of the kos plateau tuff greece coarse co ignimbrite lithic breccia ebx occurs at the base of ignimbrite e the most voluminous and widespread unit of the kos plateau tuff kpt in greece similar but generally less coarse grained basal lithic breccias dbx are also associated with the ignimbrites in the underlying d unit ebx shows considerable lateral variations in texture geometry and contact relationships but is generally less than a few metres thick and comprises lithic clasts that are centimetres to a few metres in diameter in a matrix ranging from fines bearing f2 10 wt to fines poor f2 0 1 wt lithic clasts are predominantly vent derived andesite although clasts derived locally from the underlying sedimentary formations are also present there are no proximal exposures of kpt there is a highly irregular lower erosional contact at the base of ignimbrite e at the closest exposures to the inferred vent 10 14 km from the centre of the inferred source but no ebx was deposited from 14 to 20 km from source ebx is present over a planar erosional contact at 16 km ebx is a 3 m thick coarse fines poor lithic breccia separated from the overlying fines bearing pumiceous ignimbrite by a sharp contact this grades downcurrent into a lithic breccia that comprises a mixture of coarse lithic clasts pumice and ash or into a thinner one clast thick lithic breccia that grades upward into relatively lithic poor pumiceous ignimbrite distally 27 to 36 km from source ebx is a finer one clast thick lithic breccia that overlies a non erosional base a downcurrent change from strongly erosional to depositional basal contacts of ebx dominantly reflects a depletive pyroclastic density current initially the front of the flow was highly energetic and scoured tens of metres into the underlying deposits once deposition of the lithic clasts began local topography influenced the geometry and distribution of ebx and in some cases ebx was deposited only on topographic crests and slopes on the lee side of ridges the kpt ignimbrites also contain discontinuous lithic rich layers within texturally uniform pumiceous ignimbrite these intra ignimbrite lithic breccias are finer grained and thinner than the basal lithic breccias and overlie non erosional basal contacts the proportion of fine ash within the kpt lithic breccias is heterogeneous and is attributed to a combination of fluidisation within the leading part of the flow turbulence induced locally by interaction with topography flushing by steam generated by passage of pyroclastic density currents over and deposition onto wet mud and to self fluidisation accompanying the settling of coarse dense lithic clasts there are problems in interpreting the kpt lithic breccias as conventional co ignimbrite lithic breccias these problems arise in part from the inherent assumption in conventional models that pyroclastic flows are highly concentrated non turbulent systems that deposit en masse the kpt coarse basal lithic breccias are more readily interpreted in terms of aggradation from stratified waning pyroclastic density currents and from variations in lithic clast supply from source

the origin of the north pacific intermediate water possible source regions of the north pacific intermediate water npiw were investigated with synoptic conductivity temperature depth surveys in the okhotsk sea kuril basin a pycnostad referred to as the okhotsk sea mode water osmw was found in the density range of 26 6 27 the pycnostad is not seen in the western subarctic gyre wsag thus it is an indicative water peculiar to the okhotsk sea the maximum thickness is at 26 7 26 9 centered at 26 8 which coincides with the npiw density range in the north pacific subtropical gyre in the oyashio area east of the southern kuril islands and hokkaido waters that have intermediate temperature salinity and potential vorticity between the osmw and the wsag water were distributed suggesting a following transport route of the npiw source water the thick thus low q q is potential vorticity and low salinity water mass outflowing from the okhotsk sea mixes with the relatively warm saline and high q wsag water to form the oyashio water a coastal part of the oyashio water flows southwestward along the east coast of the southern kuril islands and hokkaido retaining the pycnostad q minimum a large part of the low q oyashio water flows further southward and merges with the kuroshio extension and then flows eastward forming new npiw in this process a salinity minimum develops and the q minimum disappears because of the mixing with a saline kuroshio water old npiw without a pycnostad in the npiw density range these results suggest that the origin of npiw is the water mass in the okhotsk sea osmw and the density of the water mass primarily determines the npiw density centered at around 26 8

applicability of the k 1bar method to whole rock samples of acid lava and pumice case of the upper pleistocene domes and pyroclasts on kos island aegean sea greece abstract kos pumice which may represent an important marker for the upper pleistocene stratigraphy in the aegean area has been dated at 0 24 0 02 ma by conventional k 1bar dating on feldspar concentrates and whole rock samples this figure is at variance with the interpretation of the tephrochronological record according to which this tephra deposit would be 0 145 ma old this raises the question of a possible excess ar presenting itself in lithic fragments phenocrysts and glassy matrix of the pumice the fact that the same apparent age within error limits is obtained in the three cases makes this presence a priori improbable a large part of the common ar present in pumices is associated with the vacuoles and liberated upon grinding ar purification may be made difficult by the presence of residues of the original volcanic gases or other volatiles of uncertain origin

on magma fragmentation by conduit shear stress evidence from the kos plateau tuff aegean volcanic arc abstract large silicic explosive eruptions are the most catastrophic volcanic events yet the intratelluric mechanisms underlying are not fully understood here we report a field and laboratory study of the kos plateau tuff kpt 161 ka aegean volcanic arc which provides an excellent geological example of conduit processes that control magma vesiculation and fragmentation during intermediate to large scale caldera forming eruptions a prominent feature of the kpt is the occurrence of quite unusual platy shaped tube pumice clasts in pyroclastic fall and current deposits from the early eruption phases preceding caldera collapse on macroscopic and sem observations flat clast faces are elongated parallel to tube vesicles while transverse surfaces often occur at 45 to vesicle elongation this peculiar pumice texture provides evidence of high shear stresses related to strong velocity gradients normal to conduit walls which induced vesiculation and fragmentation of the ascending magma either an increasing mass discharge rate without adequate enlargement of a narrow central feeder conduit or a developing fissure like feeder system related to incipient caldera collapse provided suitable conditions for the generation of plate tube pumice within magma volumes under high shear during the pre climactic kpt eruption phases this mechanism implies that the closer to the conduit walls where the stronger are the velocity gradients the larger was the proportion of plate vs conventional lensoid juvenile fragments in the ascending gas pyroclast mixture consequently plate pumice clasts were mainly entrained in the outer portions of the jet and convecting regions of a sustained plinian type eruption column as well as in occasional lateral blast currents generated at the vent as a whole plate pumice clasts in the peripheral portions of the column were transported at lower altitudes and deposited by fallout or partial collapse closer to the vent relative to lensoid ones that dominated in the inner column portions the plate tube pumice proportion decreased abruptly up to disappearance during the emplacement of the main pyroclastic currents and lithic rich breccias related to extensive caldera collapse at the eruption climax as a consequence of an overall widening of the magma feeder system through the opening of multiple conduits and eruptive vents along with fissure erosion concomitant to the disruption of the collapsing block

the influence of air and sea exchange on the carbon isotope distribution in the sea we explore here the influence of the temperature dependence of isotope fractionation between atmospheric co2and ocean co2 on the distribution of carbon isotopes in the ocean this is accomplished by an analysis of departures from the expected redfield tie between po4 and 13c we find that for the surface ocean the temperature influence largely compensates for the biologic influence in the deep ocean the temperature influence imprinted at the sites of deepwater formation reduces somewhat the biologically induced difference between the carbon isotope ratios for deep waters produced in the northern atlantic and in the antarctic these same features are reproduced in the hamburg ocean model in order to assess the impact of changes in the ratio of ocean mixing rate to wind speed we have made a model run in which co2 exchange rates between air and sea were everywhere doubled as expected the influence of the thermodynamic effect on the oceanic carbon isotope distribution is magnified

significance of late permian triassic facies zones in terrane reconstructions in the alpine north pannonian domain abstract the present day setting of the tectonic units terranes making up the pre neogene basement of the pannonian basin and the west carpathians is the result of large scale displacements during the alpine collisional phases to explain this setting based on various concepts a number of models have been proposed in the last decade most of them agree in an eastward escape of the north pannonian terrane from the alpine domain towards the pannonian during the palaeogene early miocene period in the present paper a reconstruction of the pre escape setting of the displaced terranes is presented based on facies zones in selected time slices from the late permian to the late triassic according to our reconstruction the inner west carpathian units were located east of the austroalpine units forming the northern shelf of the euhallstatt meliatic basin of the vardar oceanic branch the drauzug should have been located in a position much more external than its present day setting the transdanubian range was situated in the northern neighbourhood of the southern alps whereas the bukk may have been located adjacent to the nw dinarides the mid transdanubian zone is a major shear zone containing elements of the julian alps and sava folds nappe system and the inner dinaric ophiolitic melange although the nappe tectonism may have played an important role in the structural evolution of the north pannonian terrane this mechanism alone can hardly produce hundreds of kilometres of facies offset on the opposite sides of strike slip zones

the role of subduction accretion processes in the tectonic evolution of the mesozoic tethys in serbia abstract ophiolitic rocks and melange occur in two belts in serbia to the northeast the vardar zone and to the southwest the dinaride ophiolite belt of the drina ivanjica belt which is interpreted as being a microcontinent rifted from apulia the tethys in the vardar zone has a long and complex palaeozoic early tertiary history that is still poorly understood ophiolitic rocks are known to have formed at least in the early late jurassic some of the extrusives apparently formed in a supra subduction zone setting based on immobile element geochemical evidence the mesozoic tethys in the vardar zone closed at least partly by the latest jurassic evidence from the apulian margin in the southwest and from the drina ivanjica belt further to the northeast shows that a small red sea type oceanic basin rifted in the late permian early triassic followed by spreading in the mid late triassic to early jurassic evidence from immobile trace elements shows that these extrusives are of mid ocean ridge and within plate type during the early late jurassic this southerly oceanic strand began to close creating melange as a classic subduction accretion complex morb and seamount type lavas channelised micaceous turbidites rare calciturbidites and large limestone masses capped by condensed successions were incorporated in the melange through tectonic processes many of these units originated at or near the southwestern margin of the drina ivanjica inferred microcontinent less deformed debris flows olistostromes reflect gravity reworking and or diapirism with accumulation mainly in perched basins above the subduction zone large overriding harzburgitic ophiolite thrust sheets may have developed in response to incipient spreading above a subduction zone dipping to the southwest these ophiolites were emplaced northeastwards complete with metamorphic soles in response to collision of the trench with the drina ivanjica belt southwest directed sliding of sediments into the foredeep took place prior to suturing in the tithonian and later transgression by clastic sediments

magmatism and metallogeny of the ridanj krepoljin belt eastern serbia and their correlation with northern and eastern analogues in the southwestern carpathians of sw romania and e serbia calc alkaline upper cretaceous paleogene subduction related magmatic rocks occur in two main zones the ridanj krepoljin belt e serbia represents the southern part of the western zone in this belt early maastrichtian dacites and subordinate andesites occur but there are indications of an unexposed granodioritic magmatism about 60 ma old pb zn ag and only subordinate cu mineralization is associated with this igneous activity the timok magmatic complex e serbia composed of upper cretaceous paleocene andesites and analogue intrusives represents the eastern zone south of the danube associated with this magmatism are cu au and very subordinate zn pb mineralization to the north sw romania in both zones mainly intrusive bodies diorites quartz diorites granodiorites monzonites of campanian paleocene age are exposed porphyry copper mo and in north pb zn cu mineralization are related to those intrusives the petrological and geochemical features of all these calc alkaline rocks are very similar it appears however that the associated polymetallic and the copper mineralization are both spatially and vertically separated

eoalpine to neoalpine magmatic and metamorphic processes in the northwestern vardar zone the easternmost periadriatic zone and the southwestern pannonian basin abstract the occurrence of eoalpine neoalpine genetically different granitoids and penecontemporaneous volcanics are characteristic for the vardar zone these rocks are mostly associated with late cretaceous paleogene basinal sedimentary rocks underlain by ophiolites the late cretaceous paleogene rocks were progressively metamorphosed under mediumpressure conditions and intruded by synkinematic mesoalpine granitoids the high pressure blueschist metamorphism was related to a pre maastrichtian eoalpine metamorphic event eoalpine and mesoalpine magmatism and the related metamorphism of the vardar zone may have taken place along a magmatic arc i e the subduction zone the easternmost parts of the periadriatic zone are characterized only by oligocene granitoids accompanied by penecontemporaneous volcanic rocks here younger alpine metamorphic phases only overprint and mylonitize older pre alpine formations most of the mesoalpine granite plutonism both of the vardar zone and the easternmost area of the periadriatic zone was related to subsequent extension the southwestern and southern parts of the pannonian basin contain the products of four pulses of mesoalpine and neoalpine synsedimentary volcanic activity egerian eggenburgian ottnangian carpathian badenian and post badenian represented by predominant basalt andesites trachyandesites and trachydacites this post subduction volcanism was closely connected with the cyclic marine ingressions in the pannonian basin

discrimination criteria for assigning ore deposits located in the dinaridic palaeozoic triassic formations to variscan or alpidic metallogeny among the ore deposits located in the palaeozoic triassic formations of the dinarides siderite ankerite and barite mineralization hosted by carboniferous and lower permian sediments as well as polimetalic deposits in the mid bosnian schists mts mb coused a long standing dipute concerning there metallogenic affiliations

trace element and isotope sr nd geochemistry of porphyry and skarn mineralising late cretaceous intrusions from banat western south carpathians romania geochemical and isotopic strontium neodymium data have been obtained from 24 samples of seven late cretaceous intrusions associated with skarn tincova bocsa ocna de fier dognecea and porphyry copper molybdenum skarn deposits oravi a ciclova sasca and moldova nou in the south carpathians of romania the intrusions cut the supragetic getic nappes and form a 100 km long nne ssw trending lineament in the banat metallogenic province the samples range in composition from gabbro to granodiorite and define in major and trace element variation diagrams a calc alkaline to high potassium calc alkaline trend ranging from 50 to 67 sio2 they are magnetite bearing i type granitoids enriched in lile lree and depleted in nb ta and zr common features for magmas associated with subduction zones the lack of cumulate textures and of positive europium anomalies seems to indicate that the samples represent liquid compositions the observed trend thus approximates a liquid line of descent resulting from fractional crystallisation of parental magmas with similar major and trace element compositions initial strontium isotopic ratios sri vary from 0 7042 to 0 7058 and end t values range from 3 9 to 0 2 variations of sri and end t values with sio2 show minor crustal assimilation the generally positive end t values together with moderate sri indicate that the parental magmas result from partial melting of a rubidium enriched and lree depleted source such as a heterogeneous lithospheric mantle or a young mafic lower crust derived from it selective rubidium enrichment probably occurred during a previous subduction event by metasomatism of the overlying mantle wedge either in the early cretaceous or earlier as suggested by tdm model ages ca 600 ma the cu mo pb zn fe deposits are intimately associated with the intrusions and the banat romania region can be subdivided in two metallogenic zones in northern banat fe cu pb zn skarns occur whereas in southern banat porphyry style copper and molybdenum deposits predominate these differences result from a combination of several parameters 1 magma composition whereby copper and molybdenum rich deposits tend to be associated with calc alkaline compositions 2 an increase of the present day erosion level from south to north as indicated by the presence of large equigranular plutons in northern banat and of porphyritic cupolas and apophyses associated with porphyry style mineralisation in southern banat 3 the nature of the host rocks with skarns preferentially developed in calcareous host rocks and 4 local variations of conditions controlling the infiltration of fluids and the precipitation of ore minerals

problems of the pannonian median massif and the plate tectonic concept contributions based on the distribution of late paleozoic early mesozoic isopic zones after a short historical review of conceptions about the pannonian median massif or tisia the distribution of middle upper carboniferous and lower triassic liassic facies is briefly examined on the two sides of the zagreb zemplin line dividing into two main segments the basement of the carpathian basin it shows on the one hand that the igal bukk zone igal bukk eugeosyncline ofwein 1969 thought to establish a connection between the nw dinarides and the dinaric type bukkium is only a tectonic zone and could never have been a paleogeographical unit on the other hand the northern marginal part of tisia mecsek bihor crystalline belt and its sedimentary cover dank b it was rather part of the northern northeastern marginal complex of tethys therefore allochthonous models suggesting largerscale horizontal movements give a much more plausible explanation the style of late hercynian development and the distribution of lower triassic liassic facies zones suggest that tisia was part of the northern northeastern shelf of the tethys until the end of the liassic in accordance with the opinion ofbleahu then split off and was wedged in by horizontal movements between the nw dinarides and the dinaric type bukkium by the end of the jurassic beginning of the cretaceous

decoupling of δ13cσco 2 and phosphate in recent weddell sea deep and bottom water implications for glacial southern ocean paleoceanography