thrust fault growth and segment linkage in the active ostler fault zone new zealand abstract thrust faulting is a fundamental mode of crustal deformation yet many of the key geometrical attributes of thrust faults and the controls on fault rupture growth and linkage remain poorly resolved numerous surface rupturing thrust faults cut through upper quaternary glacial outwash terraces within the ostler fault zone an active thrust system in the southern alps new zealand we use these deformed marker surfaces to define the three dimensional deformation field associated with their surface expression and to map displacement and length on 40 fault segments displacement transfer across two fault segment arrays occurs in distinctly different styles in one displacement is transferred between en echelon fault segments to produce a smooth linear displacement gradient in the other large scale folding and a population of small faults transfer displacement between two non overlapping fault segments with a residual displacement minimum within the transfer zone size distribution of fault segment length and maximum displacement follow a power law scaling relationship maximum displacement d max scales linearly with and represents 1 of segment trace length l d max l data from the segments of the ostler fault zone display similar scaling to a global fault dataset this similarity is surprising given that the observed displacements along the ostler fault represent only 20 ky of slip on fault segments that are likely to be many times older

the cryptotephra record of the marine isotope stage 12 to 10 interval 460 335 ka at tenaghi philippon greece exploring chronological markers for the middle pleistocene of the mediterranean region abstract precise chronologies that allow direct correlation of paleoclimate archives are a prerequisite for deciphering the spatiotemporal characteristics of short term climate variability such chronologies can be established through the analysis of tephra layers that are preserved in the respective sedimentary archives here we explore the yet untapped tephrochronological potential of the eastern mediterranean region for the middle pleistocene specifically for the interval spanning marine isotope stages mis 12 10 460 335 ka high resolution cryptotephra analysis was carried out on peat cores spanning the mis 12 10 interval that have been recovered from the iconic climate archive of tenaghi philippon ne greece eighteen primary cryptotephras were identified and major and trace element analyses of single glass shards from all cryptotephras were performed in order to correlate them with their eruptive sources the results suggest origins from both italian and aegean arc volcanoes specifically one cryptotephra layer could be firmly correlated with the cape therma 1 eruption from santorini which makes it the first distal tephra finding for this eruptive event while eight further cryptotephras could be tentatively correlated with their volcanic or even eruptive sources the provenance of another nine cryptotephras as yet remains unknown the relatively large number of cryptotephras that could not be assigned to specific volcanic sources and eruptive events reflects the still considerable knowledge gap regarding the geochronology and geochemistry of proximal tephra deposits from the middle pleistocene of the central and eastern mediterranean regions due to the lack of well dated middle pleistocene eruptions we provide age estimates for all cryptotephra layers identified in the mis 12 10 interval at tenaghi philippon based on high resolution pollen data from the same cores while eight of the identified cryptotephras were deposited within mis 12 438 427 ka one cryptotephra was deposited at the onset of mis 11 419 ka five cryptotephras during the younger part of mis 11 391 367 ka and four cryptotephras during mis 10 359 336 ka the high number of cryptotephras from multiple sources as recorded in the mis 12 10 interval at tenaghi philippon highlights the key role of this archive for linking tephrostratigraphic lattices for the middle pleistocene of the central and eastern mediterranean regions

petrologic constraints on the decompression history of magma prior to vulcanian explosions at the soufriere hills volcano montserrat abstract a series of 88 vulcanian explosions occurred at the soufriere hills volcano montserrat between august and october 1997 conduit conditions conducive to creating these and other vulcanian explosions were explored via analysis of eruptive products and one dimensional numerical modeling of magma ascent through a cylindrical conduit the number densities and textures of plagioclase microlites were documented for twenty three samples from the events the natural samples all show very high number densities of microlites and 50 by number of microlites have areas 2 pre explosion conduit conditions and decompression history have been inferred from these data by comparison with experimental decompressions of similar groundmass compositions our comparisons suggest quench pressures 13 75 mpa each during ascent from chamber to surface values are consistent with field studies of the same events and statistical analysis of explosion time series data the microlite volume number density trend with depth reveals an apparent transition from growth dominated crystallization to nucleation dominated crystallization at pressures of 7 mpa and lower a concurrent sharp increase in bulk density marks the onset of significant open system degassing apparently due to a large increase in system permeability above 70 vesicularity this open system degassing results in a dense plug which eventually seals the conduit and forms conditions favorable to vulcanian explosions the corresponding inferred depth of overpressure at 250 700 m near the base of the dense plug is consistent with depth to center of pressure estimated from deformation measurements here we also illustrate that one dimensional models representing ascent of a degassing crystal rich magma are broadly consistent with conduit profiles constructed via our petrologic analysis the comparison between models and petrologic data suggests that the dense conduit plug forms as a result of high overpressure and open system degassing through conduit walls

eruptive history of the late quaternary ciomadul csomad volcano east carpathians part i timing of lava dome activity located at the southern tip of the intra carpathian volcanic range in romania and composed of a dozen dacitic lava domes the ciomadul csomad volcanic complex is the youngest eruptive centre of the carpatho pannonian region whereas in the last decade the explosive history of ciomadul since 50 ka has been well constrained by numerous studies the chronology of the dome sequence still lacks robust chronological constraints and an extended analysis of all available data here we apply a detailed k ar dating approach to refine the chronology of the lava dome eruptions using the unspiked k ar cassignol gillot technique our dating focused on the most voluminous central part of the lava dome complex new eruption ages were determined following a strict separation of 10 g of groundmass from about 3 kg of unaltered sample rocks thereby isolating material whose cooling was contemporaneous with the eruption the newly applied methodology mainly consisting of a double full preparation first at larger grain size 0 4 mm and then at 100 m provides an appropriate procedure to separate suitable material to obtain the k ar age of the eruption i e the sample s groundmass in which there is no risk of the presence of older inherited crystals our new geochronological data set gives an improved insight into the temporal construction of the ciomadul volcanic complex where due to the method applied here all ages are younger than those from previous studies that used whole rock k ar ages our new results show that ciomadul s volcanic activity began with the construction of the south eastern peripheral domes from ca 850 ka to 440 ka after a ca 250 ky long repose period the activity resumed in the northern part at around 200 ka with subsequent domes emplaced between 200 and 130 ka aligned roughly north south in the western central part of the complex following a 30 ky long quiescence period the eastern central domes formed between 100 and 60 ka in addition to the chronological history of lava dome volcanism we also investigated the sequence of crystallization of mineral phases present in the lavas with respect to the modification of eruption ages ages obtained on pure minerals plagioclase amphibole and biotite are systematically older than those obtained on groundmass showing that most of them formed up to 1 85 myr before eruption in a long lived pre ciomadul magmatic system crystal size distribution csd data support the age contrasts between juvenile groundmass and older inherited minerals after injection of new magma and convective mixing with crystal clots ascent of the resulting mixture led to eruptions of material representing contrasting ages

eruptive history of a low frequency and low output rate pleistocene volcano ciomadul south harghita mts romania based on a new set of k ar age data and detailed field observations the eruptive history of the youngest volcano in the whole carpathian pannonian region was reconstructed ciomadul volcano is a dacitic dome complex located at the southeastern end of the c limani gurghiu harghita neogene volcanic range in the east carpathians it consists of a central group of extrusive domes the ciomadul mare and haramul mare dome clusters and the koves ponk dome surrounded by a number of isolated peripheral domes some of them strongly eroded balvanyos puturosul and others topographically well preserved haramul mic dealul mare one of the domes dealul cet ii still preserves part of its original breccia envelope a large number of bread crust bombs found mostly along the southern slopes of the volcano suggest that the dome building activity at ciomadul was punctuated by short vulcanian type explosive events two late stage explosive events that ended the volcanic activity of ciomadul left behind two topographically well preserved craters disrupting the central group of domes the larger diameter shallower and older mohos phreatomagmatic crater and the smaller deeper and younger sf ana sub plinian crater phreatomagmatic products of the mohos center including accretionary lapilli bearing base surge deposits and poorly sorted airfall deposits with impact sags are known close to the eastern crater rim a key section studied in detail south of b ile tusnad shows the temporal succession of eruptive episodes related to the sf ana sub plinian event as well as relationships with the older dome building stages the age of this last eruptive event is loosely constrained by radiocarbon dating of charcoal pieces and paleosoil organic matter at ca 27 35 ka the age of the mohos eruption is not constrained but we suggest that it is closely related to the sf ana eruption the whole volcanic history of ciomadul spans over ca 1 myr starting with the building up of peripheral domes and then concentrating in its central part ciomadul appears as a small volume ca 8 74 km3 and very low frequency and low output rate volcano ca 9 km3 myr at the terminus of a gradually diminishing and extinguishing volcanic range a number of geodynamically active features strongly suggest that the magma plumbing system beneath ciomadul is not completely frozen so future activity cannot be ruled out

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

palinspastic restoration of the anniston transverse zone in the appalachian thrust belt alabama abstract transverse zones are cross strike alignments of cross strike linking structures lateral ramps transverse faults and displacement transfer zones in foreland thrust belts cross strike links constitute one component of a three dimensional system of fault surfaces connecting strike parallel structures frontal ramps and detachment flats both geometrically and kinematically three dimensional palinspastic restoration provides the basis to consider causes of cross strike alignments of cross strike links into transverse zones as well as the role of transverse zones in kinematic history the anniston transverse zone in the appalachian thrust belt in alabama southeastern united states exemplifies the types and distribution of cross strike links within a transverse zone palinspastic reconstruction of the anniston transverse zone relies on matching hanging wall footwall pairs of frontal and lateral ramps for geometric balance in three dimensions in palinspastic map and cross section views cross strike links within the anniston transverse zone are systematically distributed across strike from hinterland to foreland as domains of lateral ramps transverse faults and displacement transfer zones in response to variations in depth to basement beneath the thrust belt and variations in thickness of decollement host weak rocks contrasting structural profiles characterize the thrust belt on opposite sides of the anniston transverse zone as a result of abrupt along strike changes at the cross strike alignment of cross strike links the anniston transverse zone is aligned with a northwest striking basement fault that offsets the boundary faults of the birmingham basement graben suggesting kinematic partitioning within the advancing thrust sheets at a stress concentrator the northwest striking basement fault separates domains of contrasting structural profiles of basement fault systems differing elevations of top of basement and differing thicknesses of the regional decollement host weak layer in the lower part of the sedimentary succession above basement rocks

morphometrical and geochronological constraints on the youngest eruptive activity in east central europe at the ciomadul csomad lava dome complex east carpathians abstract the timing of late pleistocene volcanic activity of the ciomadul csomad dacitic lava dome complex site of the youngest eruptions in the carpathians has been constrained by morphometric analysis and radiometric chronology pelean domes and asymmetric domes coulees built up the volcano including the central edifice that hosts the youngest twin craters of mohos mohos peat bog and lake st ana szent anna a comparative digital elevation model dem based morphometric analysis of lava domes 29 worldwide examples including 5 domes from ciomadul shows that it is the mean slope of the upper dome flank that correlates best with age although the logarithmic relationship is only moderately strong r 0 80 slope characteristics of the ciomadul domes fit to those of 10 100 ka old domes these young ages contradict the previous k ar dates giving as old as 1 ma ages on a number of domes but are supported by ongoing u pb and u th he zircon dating the latter methods constrain the whole volcanic activity to the past 250 ka and the emplacement of most lava domes within the period of 150 100 ka the volcanism at ciomadul produced alternating effusive and explosive eruptions including lava dome collapses and successive crater formations the latest possibly subplinian explosive event formed the well preserved st ana crater radiocarbon dating of organic remains from a sediment core that reached 11 m into the lacustrine infill of st ana suggests that the crater was formed prior to 26 000 years bp

the latest explosive eruptions of ciomadul csomad volcano east carpathians a tephrostratigraphic approach for the 51 29 ka bp time interval abstract the most recent mainly explosive eruptions of ciomadul the youngest volcano in the carpatho pannonian region have been constrained by detailed field volcanological studies major element pumice glass geochemistry luminescence and radiocarbon dating and a critical evaluation of available geochronological data these investigations were complemented by the first tephrostratigraphic studies of the lacustrine infill of ciomadul s twin craters st ana and mohos that received tephra deposition during the last eruptions of the volcano our analysis shows that significant explosive activity collectively called eppa early phreatomagmatic and plinian activity started at ciomadul in or around the present day mohos the older crater at 51 ka bp these eruptions resulted in a thick succession of pyroclastic fall deposits found in both proximal and medial distal localities around the volcano characterized by highly silicic rhyolitic glass chemical compositions ca 75 2 79 8 wt sio 2 the eppa stage was terminated by a subplinian plinian eruption at 43 ka bp producing pumiceous pyroclastic fall and flow deposits of similar glass composition probably from a proto st ana vent located at or around the younger crater hosting the present day lake st ana after a quiescent period with a proposed lava dome growth in the st ana crater a new explosive stage began defined as mpa middle plinian activity in particular a significant two phase eruption occurred at 31 5 ka bp producing pyroclastic flows from vulcanian explosions disrupting the preexisting lava dome of sf ana and followed by pumiceous fallout from a plinian eruption column related pyroclastic deposits show a characteristic less evolved rhyolitic glass composition ca 70 2 74 5 wt sio 2 and occur both in proximal and medial distal localities up to 21 km from source the mpa eruptions that may have pre shaped a crater similar to but possibly smaller than the present day st ana crater was followed by a so far unknown but likewise violent last eruptive stage from the same vent creating the final morphology of the crater this stage referred to as lspa latest st ana phreatomagmatic activity produced pyroclastic fall deposits of more evolved rhyolitic glass composition ca 72 8 78 8 wt sio 2 compared to that of the previous mpa stage according to radiocarbon age constraints on bulk sediment charcoal and organic matter from lacustrine sediments recovered from both craters the last of these phreatomagmatic eruptions that draped the landscape toward the east and southeast of the volcano occurred at 29 6 ka bp some 2000 years later than the previously suggested last eruption of ciomadul

breadcrust bombs as indicators of vulcanian eruption dynamics at guagua pichincha volcano ecuador vulcanian eruptions are common at many volcanoes around the world vulcanian activity occurs as either isolated sequences of eruptions or as precursors to sustained explosive events and is interpreted as clearing of shallow plugs from volcanic conduits breadcrust bombs characteristic of vulcanian eruptions represent samples of different parts of these plugs and preserve information that can be used to infer parameters of pre eruption magma ascent the morphology and preserved volatile contents of breadcrust bombs erupted in 1999 from guagua pichincha volcano ecuador thus allow us to constrain the physical processes responsible for vulcanian eruption sequences of this volcano morphologically breadcrust bombs differ in the thickness of glassy surface rinds and in the orientation and density of crack networks thick rinds fracture to create deep widely spaced cracks that form large rectangular domains of surface crust in contrast thin rinds form polygonal networks of closely spaced shallow cracks rind thickness in turn is inversely correlated with matrix glass water content in the rind assuming that all rinds cooled at the same rate this correlation suggests increasing bubble nucleation delay times with decreasing pre fragmentation water content of the melt a critical bubble nucleation threshold of 0 4 0 9 wt water exists below which bubble nucleation does not occur and resultant bombs are dense at pre fragmentation melt h2o contents of 0 9 wt only glassy rinds are dense and bomb interiors vesiculate after fragmentation for matrix glass h2o contents of 1 4 wt rinds are thin and vesicular instead of thick and non vesicular a maximum measured h2o content of 3 1 wt establishes the maxi mum pressure 63 mpa and depth 2 5 km of magma that may have been tapped during a single eruptive event more common h2o contents of 1 5 wt suggest that most eruptions involved evacuation of 1 5 km of the conduit as we expect that substantial overpressures existed in the conduit prior to eruption these depth estimates based on magmastatic pressure are maxima moreover the presence of measurable co2 17 ppm in quenched glass of highly degassed magma is inconsistent with simple models of either open or closed system degassing and leads us instead to suggest re equilibration of the melt with gas derived from a deeper magmatic source together these observations suggest a model for the repeated vulcanian eruptions that includes 1 evacuation of the shallow conduit during an individual eruption 2 depressurization of magma remaining in the conduit accompanied by open system degassing through permeable bubble networks 3 rapid conduit re filling and 4 dome formation prior to the subsequent explosion an important part of this process is densification of upper conduit magma to allow repressur ization between explosions at a critical overpressure trapped pressurized gas fragments the nascent impermeable cap to repeat the process

new seismic and tomography data in the southern part of the harghita mountains romania southeastern carpathians connection with recent volcanic activity the southern part of the southeastern carpathians represents the site of the most recent volcanic eruptions of the entire carpathian pannonian region the products of these eruptions range from 42 to 10 ka radiocarbon ages in the south harghita mountains high k calc alkaline rocks with adakite like features and at 1 2 0 6 ma k ar ages in the persani mountains alkali basalts they were emplaced in a post collisional regime ciomadul volcano is located at the southernmost part of the nw se oriented c limani gurghiu harghita range crossing the inner part of the southeastern carpathians and in the rough proximity of the vrancea seismic zone at ca 60 km toward nw its magma generation is attributed to geodynamic events closely related to the seismogenic area a number of particular geophysical and geochemical features located in the study region including 1 the abrupt attenuation of the seismic waves originating from the vrancea intermediate depth foci 2 the most intense heat flow anomaly in romania 3 the most prominent 3he 4he anomaly measured in natural postvolcanic gas emanations are all in favor of the hypothesis of a still existing hot local magma chamber data acquired during recent seismic monitoring of the vrancea zone and its neighborhoods suggest an enhancement of the local seismicity beneath the southern edge of the south harghita mts both at crustal and subcrustal levels at the same time recent tomography images obtained using local earthquake data correlate well with the presence of a vertically extended low velocity zone coming from the upper mantle to the assumed magmatic chambers located in the crust the present data supporting the presence of an active crustal magma chamber beneath ciomadul allow us to consider that future volcanic activity at this volcano cannot be discarded

the onset of the volcanism in the ciomadul volcanic dome complex eastern carpathians eruption chronology and magma type variation abstract combined zircon u th pb and u th he dating was applied to refine the eruption chronology of the last 2 myr for the andesitic and dacitic pilisca volcano and ciomadul volcanic dome complex cvdc the youngest volcanic area of the carpathian pannonian region located in the southernmost harghita eastern central europe the proposed eruption ages which are supported also by the youngest zircon crystallization ages are much younger than the previously determined k ar ages by dating every known eruption center in the cvdc repose times between eruptive events were also accurately determined eruption of the andesite at murgul mare 1865 87 ka and dacite of the pilisca volcanic complex 1640 37 ka terminated an earlier pulse of volcanic activity within the southernmost harghita region west of the olt valley this was followed by the onset of the volcanism in the cvdc which occurred after several 100s kyr of eruptive quiescence at ca 1 ma a significant change in the composition of erupted magma occurred from medium k calc alkaline compositions to high k dacitic baba laposa dome at 942 65 ka and shoshonitic magmas malnas and bixad domes 964 46 ka and 907 66 ka respectively noteworthy eruptions of magmas with distinct chemical compositions occurred within a restricted area a few km from one another these oldest lava domes of the cvdc form a nne ssw striking tectonic lineament along the olt valley following a brief ca 100 kyr hiatus extrusion of high k andesitic magma continued at dealul mare 842 53 ka after another ca 200 kyr period of quiescence two high k dacitic lava domes extruded puturosul 642 44 ka and balvanyos 583 30 ka the turnul apor lava extrusion occurred after a ca 200 kyr repose time at 344 33 ka whereas formation of the haramul mic lava dome 154 16 ka represents the onset of the development of the prominent ciomadul volcano the accurate determination of eruption dates shows that the volcanic eruptions were often separated by prolonged ca 100 to 200 kyr quiescence periods demonstration of recurrence of volcanism even after such long dormancy has to be considered in assessing volcanic hazards particularly in seemingly inactive volcanic areas where no holocene eruptions occurred the term of volcanoes with potentially active magma storage illustrates the potential of volcanic rejuvenation for such long dormant volcanoes with the existence of melt bearing crustal magma body

tertiary tectonic evolution of the external east carpathians romania abstract paleostress calculation and analysis of mesoscopic structures are integrated with depth interpreted geological profiles based on seismic studies and well correlation to derive a tertiary tectonic model for the east carpathians following early miocene and older orogenic phases the first tectonic event that affected the studied area is characterised by a wsw ene oriented shortening of middle miocene late burdigalian in age resulting deformations induced ene ward thrusting of tarcau and marginal units as well as the internal part of the subcarpathian nappe a second shortening event with an e w to wsw ene contraction direction took place in the late miocene sarmatian characterised by further foreland thrusting of the subcarpathian nappe and out of sequence deformation in the tarcau and marginal folds nappes along strike differences in deformation mechanisms are controlled by the friction coefficients along the main detachment layers by the lateral variations in the wedge thickness and by the involvement in the northern part of the thrusting system of the thick competent east european platform tear faulting occurred in both tectonic events the main resulting structure being the triangle zone developed south of the trotus valley the latest miocene latest sarmatian early pliocene is characterised by a strike slip stress field with nne ssw compression and wnw ese tension axis left lateral faults being dominant the last deformation which affected the studied area is characterised by nnw sse shortening during the pliocene major deformations taking place mainly in the sw most bending zone

cataclasites along the saltville thrust u s a and their implications for thrust sheet emplacement abstract cataclasis and frictional wear are the primary bulk deformation mechanisms along steeply dipping portions of the saltville thrust in the southern appalachian foreland zone u s a fault character ranges from a single discrete sliding surface with negligible gouge to a zone of several discrete sliding surfaces or a zone up to 0 3 m thick of pervasive cataclasite marked fracturing occurs up to 20 m above the fault whereas minimal deformation is found in the footwall rocks hanging wall dolomites range from crush breccias less than 5 matrix to ultracataclasites with 90 matrix although cataclasites 50 70 matrix are predominant foliated cataclasites occur where dolomite is thrust over shale progressive development of cataclastic fabrics is due to comminution by fracturing and grinding along intersecting fractures continued frictional grinding results in complete disruption of the original fabric to produce cataclasite and minor ultracataclasite grain alignment occurs by rigid body rotation with subsequent local enhancement by pressure solution microstructural relations of the fault gouge suggest periodic fluctuations in fluid pressure where v ratio of fluid to overburden pressure probably ranged between 0 45 and 1 the saltville thrust sheet emplacement must have occurred in a caterpillar like fashion involving aseismic and seismic shear shear stresses accompanying fault motion as determined from dolomite twin lamellae are in the order of 65 mpa

fold thrust belt evolution expressed in an internal thrust sheet sevier orogen the role of cataclastic flow large hinterland thrust sheets are the dominant structures in retroarc fold thrust belt ftb wedges these internal sheets remain active throughout the history of an ftb and strongly influence the kinematics of the external portions of the ftb and the overall behavior of the entire tectonic wedge their emplacement and deformation account for a significant portion of the total mechanical energy budget in ftb evolution based on estimates using deformation features preserved within such sheets moreover the deformation within dominant internal sheets can be used as a means to evaluate the tectonic history of the wedge as a whole the principal deformation mechanisms in different parts of an ftb wedge are strongly controlled by variations in the geothermal gradient retroarc ftbs typically show a steeper geothermal gradient in the hinterland than in the foreland resulting in a foreland ward slope of the brittl ductile transition therefore a change from plastic to elastico frictional ef mechanisms is expected not only with decreasing depth but also across strike as a dominant internal thrust sheet is transported toward the foreland and undergoes exhumation by synorogenic erosion however evidence for cataclasis overprinting early plastic deformation features is often not preserved in ancient ftbs because of extensive erosion of the wedge top even where evidence for lat stage cataclastic behavior exists in either ancient or modern i e active orogens it is often not recognized or studied our work in the canyon range central utah segment of the sevier ftb shows that unraveling the ef mechanisms such as lat stage cataclastic flow is critical to understanding the total deformation history of an internal thrust sheet after initial emplacement under plastic deformation conditions the cr thrust sheet was continuously reactivated under ef conditions thereby helping to maintain critical taper of the ftb wedge during its development structures preserved in the cr thrust sheet therefore record a significant portion of the deformation history of the ftb as a whole the canyon range cr syncline part of the cr sheet underwent fold tightening within the ef regime and the cataclasized rocks are well preserved the geometry and progressive deformation patterns of the cr syncline reveal four distinct to partly overlapping deformation stages the history of the rocks in the cr thrust sheet has been tracked by incrementally retro deforming the ftb and by unraveling details of the deformation within the cr syncline at various scales for each stage we use the cr syncline as a type example to show that unraveling ef mechanisms is critical to 1 understanding the state of a ftb wedge during its evolution 2 calculating the energy involved in ftb emplacement and 3 developing accurate restorations placing constraints on the depth of the rocks for successive stages of deformation is essential for developing retrodeformable balanced cross sections and in turn geometric and kinematic models for wedge evolution

differential displacement and rotation in thrust fronts a magnetic calcite twinning and palinspastic study of the jones valley thrust alabama us appalachians to test whether a displacement gradient along a curved fault structure requires rotation we studied the northeast striking northwest verging large displacement jones valley thrust fault of the appalachian thrust belt in alabama paleomagnetism anisotropy of magnetic susceptibility ams and calcite twinning analysis complemented by balanced cross sections were used to evaluate the presence and magnitude of any rotation remanence directions from the silurian red mountain formation reveal a prefolding magnetization acquired in the pennsylvanian whereas magnetic analysis shows a strong bedding parallel compaction fabric with a tectonic lineation paleomagnetic directions and magnetic lineations reveal no relative rotation between the hanging wall and footwall of the thrust fault rather than rotation therefore we interpret the jones valley thrust sheet as a structure that developed in a self similar fashion with lateral growth of the fault surface occurring coincident with growth into the foreland

episodes of dormancy and eruption of the late pleistocene ciomadul volcanic complex eastern carpathians romania constrained by zircon geochronology abstract ciomadul is the youngest volcanic system in the carpathian pannonian region recording eruptive activity from ca 1 ma to 30 ka based on combined zircon u th and u th he geochronology ciomadul volcanism is divided into two main eruptive periods old ciomadul 1 ma 300 ka ocep and young ciomadul eruptive period 160 30 ka ycep ocep activity comprises eruptive epochs 1 3 whereas new ages for eight lava domes and four pyroclastic units belonging to the ycep lead to its further subdivision into two eruptive epochs eruptive epochs 4 and 5 the extrusion of most of the lava domes occurred between 160 and 90 ka eruptive epoch 4 during three eruptive episodes at ca 155 ka 135 ka and 95 ka eruptive episodes 4 1 4 2 and 4 3 respectively along a ne sw lineament which is perpendicular to the regional nw se trend of the c limani gurghiu harghita volcanic chain eruptive epoch 5 occurred after a ca 40 kyr of quiescence at ca 55 30 ka and is mainly characterized by explosive eruptions with a minor lava dome building activity all of the dated pyroclastic outcrops together with the lava dome of piscul pietros belong to the older eruptive episode 5 1 with an eruption age of 55 45 ka the eruption centers of eruptive epoch 5 are located at the junction of the conjugated nw se and ne sw lineaments defined by the older eruptive centers the whole rock geochemistry of all studied samples is fairly homogeneous sio2 63 69 wt k2o 3 4 wt it also overlaps with the composition of the lava domes of the old ciomadul eruptive period implying a monotonous geochemical characteristic for the past 1 myr the eruption rates for the ciomadul volcanism were determined based on the erupted lava dome volume calculations supplemented with the eruption ages the activity peaked during the eruptive epoch 4 160 90 ka having an eruption rate of 0 1 km3 kyr in comparison these values are 0 05 km3 kyr for the ycep 160 30 ka and 0 01 km3 kyr for the overall ciomadul volcanism 1 ma 30 ka based on the geochemical characteristics the quiescence periods and the lifetime of the complex as well as the relatively small amount of erupted material this volcanic system can be placed in a subduction related post collisional geodynamic setting which shows strong chemical similarities to continental arc volcanism the commonly found long repose times between the active phases suggest that the nature of a volcano cannot be understood solely based on the elapsed time since the last eruption instead comprehensive geochronology coupled with the understanding of the magma storage behavior could be a base of hazard assessment for volcanic fields where the last eruptions occurred several 10 s of thousand years ago and therefore they are not considered as potentially active

paleomagnetism of the gran sasso range salient central apennines italy pattern of orogenic rotations due to translation of a massive carbonate indenter 1 we report on the paleomagnetism 39 new sites of gran sasso an indenter controlled salient of the external central apennines formed by two orthogonal limbs we find that gran sasso is a complex salient paleomagnetically corresponding to neither a nonrotating nor an oroclinal end member data from the core of the arc show that the indenter itself did not undergo any rotation conversely rotations of variable magnitude and sign are observed along the curve shaped thrust fronts rotations are virtually absent at both end points of the arc moving toward the apex progressively greater counterclockwise ccw and clockwise cw rotations occur along the e w and n s fronts respectively the rotations increase continuously and more than linearly reaching their maximum values 80 ccw and 50 cw around the apex here the more strongly ccw and cw rotated fronts are separated by a domain characterized by local block rotations the inequality between the maximum ccw and cw rotation values is likely a consequence of the asymmetry of the indenter displacement direction n70 e with respect to the preorogenic trends of its margins e w and n s from an oroclinal point of view the fronts close to the end points virtually define a nonrotating arc while the pattern around the apex is similar to that of an orocline we conclude that close to end points nonrotational thrusting normal to the indenter margins occurred while in the vicinity of the apex the peritidal carbonates acted as an ice breaker pushing apart and strongly rotating the weaker multilayer located ahead

tectonic significance of changes in post subduction pliocene quaternary magmatism in the south east part of the carpathian pannonian region the south eastern part of the carpathian pannonian region records the cessation of convergence between the european platform moesia and the tisza dacia microplate plio quaternary magmatic activity in this area in close proximity to the vrancea zone shows a shift from normal calc alkaline to much more diverse compositions adakite like calc alkaline k alkalic mafic na alkalic and ultrapotassic suggesting a significant change in geodynamic processes at approximately 3 ma we review the tectonic setting timing petrology and geochemistry of the post collisional volcanism to constrain the role of orogenic building processes such as subduction or collision on melt production and migration the calc alkaline volcanism 5 3 3 9 ma marks the end of normal subduction related magmatism along the post collisional c limani gurghiu harghita volcanic chain in front of the european convergent plate margin at ca 3 ma in south harghita magma compositions changed to adakite like calc alkaline and continued until recent times 0 03 ma interrupted at 1 6 1 2 ma by generation of na and k alkalic magmas signifying changes in the source and melting mechanism we attribute the changes in magma composition in front of the moesian platform to two main geodynamic events 1 slab pull and steepening with opening of a tear window adakite like calc alkaline magmas and 2 renewed contraction associated with deep mantle processes such as slab steepening during post collisional times na and k alkalic magmas contemporaneous post collisional volcanism at the eastern edge of the pannonian basin at 2 6 1 3 ma was dominated by na alkalic and ultrapotassic magmas suggesting a close relationship with thermal asthenospheric doming and strain partitioning related to the adriatic indentation similar timing magma chamber processes and volume for k alkalic shoshonitic magmas in the south apuseni mountains 1 6 ma and south harghita area at a distance of ca 200 km imply a regional connection with the inversion tectonics

palaeowind directions and sources of detrital material archived in the roxolany loess section southern ukraine abstract measurements of the anisotropy of whole rock magnetic susceptibility ams and u pb ages of detrital zircons have been combined to define the palaeowind directions and sources of wind blown dust in the loess palaeosol key section at roxolany southern ukraine zircon dating has also been used to determine the age and provenance of the interbedded roxolany tephra the distribution of ams axes in the loess indicates that the prevailing wind during its accumulation blew from the north west the same as the mean present day summer wind direction measured in the nerby city of odessa the u pb isotopic ages of the detrital zircons mostly range between 0 25 and 2 ga with clusters at 0 28 0 32 0 45 0 58 1 0 and 1 5 ga single neoarchean grains ca 2 7 ga were also found these ages indicate that material from carpathian and podolian sources formed the roxolany loess this material initially was transported by the dniester river then was wind blown form the dniester liman and the lower dniester valley located nw of roxolany most of the pyroclastic zircons from the roxolany tephra gave ages of 470 840 ka with a peak between 500 and 750 ka this age range is consistent with their being derived from the ciomadul volcano in romania

the roxolany tephra ukraine new evidence for an origin from ciomadul volcano east carpathians we present major element glass data and correlations for the roxolany tephra a so far geochemically unconstrained volcanic ash layer previously described in last glacial marine isotope stage 2 loess deposits of the roxolany loess palaeosol complex in south west ukraine this exceptionally well preserved 2 3 cm thick tephra layer is characterized by a rhyolitic glass composition that is comparable to that of proximal tephra units from ciomadul volcano in the east carpathians central romania the chemistry particularly matches that of the final latest st ana phreatomagmatic activity pyroclastic fall unit of st ana crater that is radiocarbon dated in the proximal mohos coring site moh 2 to 29 6 0 62 cal ka bp the age of the tephra correlative agrees with the newest radiocarbon and infrared optically stimulated luminescence age constraints from overlying palaeosols and tephra embedding loess of the roxolany sequence respectively which place the tephra between ca 33 and 24 cal ka bp and thus confirm the long debated chronostratigraphy of this important environmental archive the occurrence of a distal ciomadul tephra ca 350 km east of its source indicates great potential for further tephra and cryptotephra findings from this volcanic complex in the south eastern mediterranean and black sea region

paleomagnetic study of thrust sheet rotation during foreland impingement in the wyoming idaho overthrust belt upper jurassic and lower cretaceous strata in the darby and absaroka thrust sheets were sampled in order to paleomagnetically evaluate thrust sheet rotation in the wyoming idaho overthrust belt no significant rotations were found lack of rotation in these thrust sheets suggests that previously reported rotation of the prospect thrust sheet was not transmitted to the older darby and absaroka thrust sheets indicating that the prospect thrust sheet only experienced local rotations in response to collision with the teton gros ventre uplift the upper jurassic stump formation possesses a magnetization that passes the fold test and gives a paleomagnetic pole at 64 n 170 e k 18 a95 15 in good agreement with other published upper jurassic poles for cratonic north america samples from all lower cretaceous sites are believed to possess a synfolding remagnetization of chemical origin

the thermal response of a metamorphic belt to extension constraints from laser ar data on metamorphic micas abstract metamorphic rocks may be exhumed to the surface either by isostatic rebound uplift and erosion or tectonically via thrusting or extension the latter mechanism is particularly important in the himalayas where a large extensional detachment system appears to be responsible for very fast unroofing at 20 ma here we present the results of a laser argon study of micas and quartz aimed at investigating the thermal response of an orogenic belt to such extension the data when combined with existing constraints on the prograde evolution lead to a uniquely complete thermal history for a metamorphic belt laser argon data are reported for quartz and micas from semi pelitic metamorphic rocks from the zanskar himalayas nw india the samples derive from three traverses extending from low grade rocks near the detachment to high grade rocks in the core of the belt most samples demonstrably contain no excess component and the ages of muscovite and biotite show a correlation with distance from the extensional detachment the ages themselves as well as the difference between the muscovite and biotite ages both increase as the detachment is approached muscovite and biotite ages from within the shear zone date deformation associated with extension at 20 25 ma the remaining data are most readily interpreted in terms of early slow cooling of the lower grade rocks near the detachment in response to erosional denudation before the detachment became active rocks in the core of the orogen were still heating at this time later fast cooling of the high grade rocks in the core of the belt ensued when the extensional regime became active simple heat transfer calculations based on the distance of the high grade rocks from the fault and the argon ages of their micas provide further constraints on the timing of extension and suggest that the fault first moved 23 25 ma ago and that it abruptly terminated metamorphism in the core of the metamorphic belt our analysis of the thermal history suggests that cooling and exhumation rates determined from metamorphic belts beneath extensional detachments will often be minima

large scale deformation in a locked collisional boundary interplay between subsidence and uplift intraplate stress and inherited lithospheric structure in the late stage of the se carpathians evolution 1 the interplay between slab dynamics and intraplate stresses in postcollisional times creates large near surface deformation particularly in highly bent orogens with significant lateral variations in mechanical properties this deformation is expressed through abnormal foredeep geometries and contrasting patterns of vertical movements intraplate folding is often the controlling mechanism particularly when the orogenic belt is locked the study of these tectonic processes in the se carpathians indicates a generalized subsidence period during latest miocene pliocene times driven by the slab pull and an intraplate folding due to an overall quaternary inversion the latter accommodates 5 km ese ward movement of this area with respect to the neighboring units which creates complicated three dimensional deformation patterns potentially driven at a larger scale by the interaction between the adriatic indentor and the entire carpathians system the lithospheric anisotropy inherited from the subduction times concentrates strain and induces large scale deformation far away from the active plate margins this anisotropy is dynamic because of deep mantle processes related to the subducted slab during postcollisional times such as thermal reequilibration or increase in slab dip

quantification of carbon dioxide emissions of ciomadul the youngest volcano of the carpathian pannonian region eastern central europe romania abstract we provide the first high resolution co 2 flux data for the neogene to quaternary volcanic regions of the entire carpathian pannonian region eastern central europe and estimate the co 2 emission of the seemingly inactive ciomadul volcanic complex the youngest volcano of this area our estimate includes data from focused and diffuse co 2 emissions from soil the co 2 fluxes of focused emissions range between 277 and 8172 g d 1 corresponding to a co 2 output into the atmosphere between 0 1 and 2 98 t per year the investigated areas for diffuse soil gas emissions were characterized by wide range of co 2 flux values at apor baths ranging from 1 7 10 1 to 8 2 10 4 g m 2 d 1 while at l z re ti ranging between 1 43 and 3 8 10 4 g m 2 d 1 the highest co 2 focused gas fluxes at ciomadul were found at the periphery of the youngest volcanic complex which could be explained either by tectonic control across the brittle older volcanic edifices or by degassing from a deeper crustal zone resulting in co 2 flux at the periphery of the supposed melt bearing magma body beneath ciomadul the estimate of the total co 2 output in the area is 8 70 10 3 t y 1 and it is consistent with other long 10 kyr dormant volcanoes with similar age worldwide such as in italy and usa taking into account the isotopic composition of the gases that indicate deep origin of the co 2 emissions this yields further support that ciomadul may be considered indeed a dormant or pams volcano volcano with potentially active magma storage rather than an inactive one furthermore hazard of co 2 outpourings has to be taken into account and it has to be communicated to the visitors finally we suggest that co 2 output of dormant volcanic systems has to be also accounted in the estimation of the global volcanic co 2 budget

eruptive history of the late quaternary ciomadul csomad volcano east carpathians part ii magma output rates this study which builds on high precision unspiked cassignol gillot k ar age determinations presents an advanced dem based volumetrical analysis to infer long term magma output rates for the late quaternary ciomadul csomad dacitic lava dome complex east carpathians romania the volcanic field of ciomadul developed on the erosional surface of lower cretaceous flysch and 2 ma old andesites and experienced an extended eruptive history from 850 to 30 ka predominantly effusive activity took place during the first stage 850 to 440 ka producing volumetrically minor isolated peripheral domes subsequently after a 250 ky repose interval a voluminous central dome cluster developed in the second stage 200 to 30 ka during the youngest phase of evolution 60 to 30 ka highly explosive eruptions also occurred resulting in the formation of two craters mohos and st ana the calculated 8 00 0 55 km3 total volume of the lava domes which includes the related volcaniclastic 1 57 km3 as well as erosionally removed 0 18 km3 material is in line with dimensions of other medium sized dacitic lava domes worldwide this volume was extruded at an average long term magma output rate of 9 76 km3 my 0 0098 km3 ky however most of the domes 7 53 0 51 km3 were formed in the 200 to 30 ka period implying a significantly increased magma output rate of 37 40 km3 my 0 0374 km3 ky more than 30 times higher than in the first stage within these long term trends individual lava domes of ciomadul e g those with volumes between 0 02 and 0 40 km3 would have been emplaced at much higher rates over a period of years to tens of years the active periods lasting up to hundreds of years would have been followed by repose periods 30 times longer the most recent eruption of ciomadul has been dated here at 27 7 1 4 ka this age which is in agreement with radiocarbon dates for the onset of lake sediment accumulation in st ana crater dates fragmented lava blocks which are possibly related to a disrupted dome this suggests that during the last typically explosive phase of ciomadul lava dome extrusion was still ongoing in a global context the analysis of the volumetric dynamism of ciomadul s activity gives insights into the temporal variations in magma output at lava domes short term day or week scale eruption rates smooth out in long term millenia scale output rates which are tens of times lower

fingerprinting the late pleistocene tephras of ciomadul volcano eastern central europe late pleistocene tephras derived by large explosive volcanic eruptions are widespread in the mediterranean and surrounding areas they are important isochronous markers in stratigraphic sections and therefore it is important to constrain their sources we report here tephrochronology results using multiple criteria to characterize the volcanic products of the late pleistocene ciomadul volcano in eastern central europe this dacitic volcano had an explosive eruption stage between 57 and 30 ka the specific petrological character ash texture occurrence of plagioclase and amphibole phenocrysts and their compositions the high k calc alkaline major element composition and particularly the distinct trace element characteristics provide a strong fingerprint of the ciomadul volcano this can be used for correlating tephra and cryptotephra occurrences within this timeframe remarkably during this period several volcanic eruptions produced tephras with similar glass major element composition however they differ from ciomadul tephras by glass trace element abundances ratios of strongly incompatible trace elements and their mineral cargo that serve as discrimination tools we used u th he zircon dates combined with u th in situ rim dates along with luminescence and radiocarbon dating to constrain the age of the explosive eruptions of ciomadul that yielded distal tephra layers but lack of identified proximal deposits

tectono magmatic characteristics of post collisional magmatism case study east carpathians călimani gurghiu harghita volcanic range abstract this work provides a comprehensive gis mapping integrated with geological and geophysical data magnetic and gravimetric to reveal the interplay between i magmatism and volcanic activity ii intra mountain basin development and iii large scale faulting tectonic features in the post collisional setting of the east carpathians the geological geophysical and tectonic data of the c limani gurghiu harghita range cgh confirm the contemporaneous formation of basins and volcanic activity the two phenomena propagated southwards in time parallel to the collisional front in close relation to the development of the fault systems the geometry of the faults and alignment of volcanic edifices indicate both strike slip and normal faulting with no rotation the main volcanic range and main tectonic basins evolved along a regional nnw sse striking sinistral transtensional fault zone with left stepping stepovers and pull apart basins in the transfer areas the fault zones probably acted as least resistance areas that fostered the development of magma ascent paths and plumbing systems these connected the volcanic centers with numerous magma chambers emplaced at the upper mantle lower crust boundary and throughout the lower and upper crust the magma generation is most likely a result of the interplay between large scale transtensional systems that induced decompression in the previously metasomatised mantle and asthenosphere upwelling in the post collisional east carpathian orogen

migration of deformation fronts during progressive deformation evidence from detailed structural studies in the pennsylvania anthracite region u s a abstract detailed study of selected outcrops in the pennsylvania anthracite region has resulted in identification of five at least partly continuous stages of alleghanian progressive deformation these structural stages are in sequence a layer parallel shortening and top to the foreland layer parallel shear b a second episode of layer parallel shortening c flexural slip and flexural flow folding d fold modification and late thrust faulting and e late veining and fracturing at each outcrop an average shortening direction was determined for each observed structural stage the mean regional shortening direction for each structural stage was calculated and maps showing the spatial distribution of the shortening directions for each stage were constructed the mean regional shortening directions for the five structural stages successively rotated 25 30 clockwise during the evolution of the fold and thrust belt shortening directions for structural stages b and c over the region show a systematic clockwise change in orientation from hinterland to foreland indicating that these structural stages of progressive deformation were time transgressive on a regional scale

helium and carbon isotope systematics at ontake volcano japan we have measured chemical compositions he ne ratios and he and c isotopic compositions of 47 gas samples collected from crater fumaroles and hot springs associated with ontake volcano japan geographical and temporal variations of chemical compositions 3he 4he ratios and 13c values of co2 are reported here between 1981 and 1993 3he 4he ratios decreased with increasing distance from the central cone of the volcano while 13c values increased with the distance magmatic he and co2 are probably carried by a fluid flowing through the volcanic edifice and are diluted by crustal he and co2 a negative correlation of 3he 4he ratios and 13c values suggests two component mixing between magmatic and crustal end members at the sampling sites close to the fault formed by a m6 8 earthquake that occurred in september 1984 3he 4he ratios have increased significantly with time from 1984 to 1993 while except for three sites close to the fault no systematic change of 13c values is found on the other hand he and c isotopes have been constant at the sites distant from the fault the temporal variations of 3he 4he ratios may be related to the recent reactivation of ontake volcano

genesis and evolution of a curved mountain front paleomagnetic and geological evidence from the gran sasso range central apennines italy abstract the gran sasso range is a striking salient formed by two roughly rectilinear e w and n s limbs in the past 90 counterclockwise ccw rotations from the eastern gran sasso were reported tectonophysics 215 1992 335 suggesting west east increase of rotation related northward shortening along the e w limb in this paper we report on paleomagnetic data from meso cenozoic sedimentary dykes and strata cropping out at corno grande central part of the e w gran sasso limb the highest summit of the apennine belt predominant northwestward paleomagnetic declinations in the normal polarity state from both sedimentary dykes and strata are observed when compared to the expected declination values for the adriatic foreland our data document no thrusting related rotation at corno grande the overall paleomagnetic data set coupled with the available geological information shows that the gran sasso arc is in fact a composite structure formed by an unrotated low shortening western e w trending limb and a strongly ccw rotated eastern salient late messinian and post early pliocene shortening episodes documented along the gran sasso front indicate that belt building and arc formation occurred during two distinct episodes we suggest that the southern part of a late messinian n s front was reactivated during early middle pliocene time forming a tight range salient due to ccw rotations and differential along front shortening rates the formation of a northward displacing bulge in an overall nw se chain is likely a consequence of the collision between the latium abruzzi and apulian carbonate platforms during northeastward propagation of the apennine wedge inducing lateral northward extrusion of latium abruzzi carbonates towards ductile basinal sediment areas

constraints on the timing of quaternary volcanism and duration of magma residence at ciomadul volcano east central europe from combined u th he and u th zircon geochronology article i nfo high spatial resolutionzircon geochronologywas applied to constrain thetimescalesof volcaniceruptions of the youngest mostly explosive volcanic phase of ciomadul volcano carpathian pannonian region romania com bined u th and u th he zircon dating demonstrates that intermittent volcanic eruptions occurred in a time range of 56 32 ka the reliability of the eruption dates is supported by concordant ages obtained from different dating techniques such as zircon geochronology radiocarbon analysis and infrared stimulated luminescence dating for the same deposits the new geochronological data suggest that volcanism at ciomadul is much youn ger bca 200 ka than previously thought up to 600 ka a dominantly explosive volcanic phase occurred after an apparent lull in volcanism that lasted for several 10 s of ka after a period of lava dome extrusion that defines the onset of the known volcanism at ciomadul at least four major eruptive episodes can be distinguished within the 56 32 ka period among them relatively large sub plinian to plinian explosive eruptions produced distal tephra covering extended areas mostly southeast from the volcano the 38 9 ka tephra overlaps the age of the campanian ignimbrite eruption and has an overlapping dispersion axis towards the black sea region the wide range of u th model ages of the studied zircons indicates prolonged existence of a low temperature b800 c silicic crystal mush beneath ciomadul the main zircon crystallization period was between ca 100 and 200 ka coeval with the older mostly extrusive lava dome building stage of volcanism even the youngest u th model ages obtained for the outermost 4 m rim of individual zircon crystals predate the eruption by several 10 s of ka the zircon age distributions suggest re heating above zircon saturation temperatures via injection of hot mafic magmas prior to eruption intermittent intrusions of fresh magma could play a significant role in keeping the intrusive silicic magmatic reservoir in a partially melted for prolonged period the previous history of ciomadul suggests that melt bearing crystal mush resided beneath the volcano and was rapidly remobilized after a protracted several 10 s of ka lull in volcanism to trigger several eruptions in a comparatively short time window this classifies ciomadul as a volcano with potentially active magma storage pams which we propose to be common among the seemingly inactive volcanoes in volcanic arc regions the potential for reacti vation of these systems should be included into volcanic hazard assessments

new chronological constraints for middle palaeolithic mis 6 5 3 cave sequences in eastern transylvania romania abstract the middle to upper palaeolithic transition is one of the crucial periods of change in the prehistory of europe due to the full emergence continent wide of modern human lithic technologies and detrimental of neanderthal survival knowledge about the transition is growing however the evidence for cultural and technological developments for the middle palaeolithic in the carpathian lower danube basin is still rather sparse here we discuss latest findings arising from a chronological investigation of middle palaeolithic assemblages within the varghis karst eastern transylvania romania combining our first chronological results with information from previous excavations we can distinguish two main stages of habitation albeit middle palaeolithic lithics and faunal remains appear scattered throughout the investigated profile within the abri 122 rock shelter in order to augment the typological cultural considerations we applied direct radiocarbon dating on bones and charcoal from within the occupation layers radiocarbon dating of bones suggests that the middle palaeolithic sequence is older than the upper dating limit of the method whereas direct luminescence ages on the lowermost productive horizon and immediately above it indicate surprisingly old ages of ca 106 141 ka osl optically stimulated or 99 174 ka irsl infrared stimulated multiple protocol dating of charcoal found within the two habitation layers produced ages 38 14 c ka bp also suggesting that the lowermost lithic rich horizon pertains to the middle palaeolithic industries overall the recovered lithics currently forming one of the most significant collections for romania are fully consistent with two main habitation phases connected to middle palaeolithic cultural affinities the occurrence of a volcanic ash layer within ursului cave and originating from the ciomadul volcanic complex carpathians is first reported here recently dated to 43 50 ka it might represent an important marker horizon providing that it is identified within other palaeolithic cave assemblages