evidence of early cretaceous collisional style orogenesis in northern fiordland new zealand and its effects on the evolution of the lower crust structural metamorphic and kinematic data from a well exposed section of lower crustal rocks in northern fiordland new zealand reveal a history of intense contractional deformation and high p metamorphism at the roots of a convergent orogen high p 14 kbars granulite facies garnet clinopyroxene bearing reaction zones occur adjacent to anorthositic veins within gabbroic and dioritic gneiss these veins and reaction zones were variably deformed by two phases of high p granulite facies deformation quantitative kinematic analyses conducted using systems of rotated veins and reaction zones indicate that the first phase produced steeply dipping shear zones within a sinistral pure shear dominated flow regime wk 0 69 this deformation occurred at conditions of p 14 0 1 3 kbars and t 676 34 c and resulted in subhorizontal arc parallel ne sw stretching and up to 60 subhorizontal shortening in high strain zones of the lower crust at depths 45 km the second phase of deformation occurred at p 14 1 1 2 kbars and t 674 36 c and produced vertically stacked gently dipping ductile thrust faults that accommodated arc normal nw directed displacement these features reflect major tectonic thickening of the crust oblique convergence and high p metamorphism during the collision of the roots of a convergent orogen represented by plutons of the median tectonic zone in eastern fiordland with the paleo pacific margin of gondwana represented by western fiordland distinctive kinematic styles suggest that this collision resulted in a partitioning of the arc parallel ne sw and arc normal nw se components of oblique convergence onto sinistral strike slip and ductile thrust faults respectively at lower crustal levels

thermomechanical evolution of the crust during convergence and deep crustal pluton emplacement in the western province of fiordland new zealand 1 fiordland new zealand contains exposures of high pressure p 12 14 kbar granulite facies rocks that form one of earth s largest exposed lower crustal roots of an early cretaceous magmatic arc these exposures allowed us to examine the mechanisms and processes that controlled crustal thickening and large vertical displacements at the deepest levels of a deforming arc system we present structural and metamorphic data that show how the root of this arc was tectonically thickened by imbricate granulite facies thrust zones during and after the emplacement of sheeted plutons into the middle and lower crust the imbricate thrust zones form part of a well exposed 12 km wide two sided fold thrust belt that preferentially developed in crust that was thermally softened by magmatism changes in metamorphic mineral assemblages and microstructural data from the contact aureole of a composite arc batholith called the western fiordland orthogneiss record thrust and pluton emplacement conditions of p 7 9 kbar paleodepths of 25 30 km these data show that thrust imbrication and tectonic loading at 30 km depth is a viable mechanism of large vertical displacements and crustal thickening at the deepest levels of magmatic arcs this mechanism produced a characteristic up pressure metamorphic history that is similar to that observed in many other large magmatic belts worldwide

transition from island arc to passive setting on the continental margin of gondwana u pb zircon dating of neoproterozoic metaconglomerates from the se margin of the tepla barrandian unit bohemian massif abstract sedimentological petrological and geochemical data combined with shrimp and la icp ms u pb ages of pebbles of granitic rocks and detrital zircons from neoproterozoic vletice metaconglomerates of the se margin of the tepla barrandian unit were used to characterize the regional geotectonic setting at the proterozoic paleozoic boundary the metaconglomerates form several metres thick intercalations in metasediments of the svrchnice formation roof pendants of central bohemian plutonic complex which is considered to have been deposited in neoproterozoic cambrian times a sedimentological study indicates that the metaconglomerates are products of debris flows deposited in submarine canyons or proximal parts of submarine fans geochemistry of metaconglomerate matrix and petrography of pebbles revealed an obvious difference from the western and central part of the tepla barrandian unit proterozoic where pebbles eroded from uplifted parts of the basin and island arc sources are most common the abundance of quartz quartzite granite and crystalline limestone in pebbles together with the more mature composition of host metagreywackes indicate the presence of relatively evolved continental crust in the source area for the vletice metaconglomerates and shallowing of the neoproterozoic basin to the se in the present geographic co ordinate system the neoproterozoic to lowermost cambrian age of the svrchnice formation suggested by its comparison with similar rocks in the central part of the tepla barrandian unit was confirmed by u pb dating ages of detrital zircons from the metaconglomerate matrix cluster around two values archaean to paleoproterozoic u pb ages between ca 2580 and 1780 ma and neoproterozoic to early cambrian ages between 660 and 520 ma with a significant peaks at 600 and 544 ma suggesting local volcanic activity extending shortly beyond the proterozoic paleozoic boundary zircons separated from two trondhjemite pebbles from the metaconglomerate yielded a mean u pb age of 610 17 ma arguing for active arc magmatism during the latest neoproterozoic the overall age distribution of detrital zircons and the absence of grenvillian zircon ages favour a location of the tepla barrandian unit close to the west african craton at the neoproterozoic paleozoic boundary the rapid onset of a transtensional geotectonic regime and maturing of sediments is evidenced by the overlying cambrian shallow water clastics alternating with predominantly felsic calc alkaline to alkaline volcanics during the cambrian oblique plate convergence the active continental margin was transformed into belts of horsts and narrow pull apart or small rift basins after the ordovician break off of armorican terrane assemblage blocks from gondwana the extensional regime in the tepla barrandian unit continued until the beginning of variscan orogeny in the middle devonian

seismic anisotropy of the upper crust in southeastern poland effect of the compressional deformation at the eec margin results of celebration 2000 seismic data inversion 1 analysis of the data from celebration 2000 experiment in southeastern poland revealed azimuthal variation of the vp velocity unlikely to be caused by crustal inhomogeneity this is explained by upper crustal seismic anisotropy and was analysed by the anisotropic delay time inversion the result indicating 8 10 anisotropy fits to the geology of the area where tightly folded metapelitic rocks are abundant the fast velocity axis direction of 115 wnw ese coincides well with the azimuths of outcropping folds axes and other deformational structures in order to assess the credibility of the result synthetic tests have been performed the traveltimes calculated for isotropic models were inverted to check if an artificial anisotropy will be generated the tests indicate that realistic isotropic velocity inhomogeneities can only account for a fraction of observed traveltime variations and that the anisotropy cannot be an artifact resulting from the inhomogeneous crust

timing styles and kinematics of cambro ordovician extension in the tepla barrandian unit bohemian massif and its bearing on the opening of the rheic ocean this paper describes late cambrian dikes and early ordovician volcano sedimentary successions of the prague basin bohemian massif to discuss the timing and kinematics of breakup of the northern margin of gondwana andesitic dikes indicate minor e w crustal extension in the late cambrian whereas the tremadocian to dapingian lithofacies distribution and linear array of depocenters suggest opening of this rheic ocean rift related basin during nw se pure shear dominated extension this kinematic change was associated with the onset of basic submarine volcanism presumably resulting from decompression mantle melting as the amount of extension increased we conclude from these inferences and from a comparison with other avalonian cadomian terranes that the rifting along the northern gondwana margin was a two stage process involving one major pulse of terrane detachment in the early cambrian and one in the early ordovician while the geodynamic cause for the former phase remains unclear but still may include effects of cadomian subduction roll back slab break off isostatic rebound or mantle plume the incipient stage of the latter phase may have been triggered by the onset of subduction of the iapetus ocean at around 510 ma followed by advanced extension broadly coeval tremadocian to darriwilian in large portions of the avalonian cadomian belt unequal amounts of extension resulted in the separation and drift of some terranes while other portions of the belt remained adjacent to gondwana

processes controlling vertical coupling and decoupling between the upper and lower crust of orogens results from fiordland new zealand the pre cenozoic configuration of western new zealand allows determination of the effects of magmatism and a changing lower crustal rheology on the evolution of a cretaceous orogen from upper to lower crustal levels 10 50 km beginning at 126 ma a composite batholith dominated by diorite was emplaced into the lower crust during emplacement deformation was partitioned into zones weakened by magma and heat leading to the development of two layer parallel shear zones at the upper and lower contacts of the batholith transient vertical decoupling of the crust above and below the batholith occurred from 126 ma until 120 ma as magma was emplaced into and moved through a weak thick lower crust by 116 ma however much of the batholith had crystallized and the lowermost crust had cooled from 750 c t 850 c to t 650 700 c cooling was aided by the juxtaposition of pre existing crust against hot new crust and by the efficient extraction of partial melts out of the lower crust cooling together with dehydration of the lower crust and mafic compositions led to the development of a strong dry lower crustal root by 116 ma a strong lower crust resulted in high degrees of vertical coupling between the upper and lower crust during contraction from 116 to 105 ma even as magma continued to be emplaced into the mid upper crust a narrow focused orogenic style in the upper crust at this time reflected a highly viscous lower crust through which compressional stresses were transferred vertically the results imply that changes in plate boundary dynamics rather than the thermal weakening of thick lower crust during convergence controlled the onset of regional extension at 108 105 ma

potential field imaging of palaeozoic orogenic structure in northern and central europe abstract the trans european suture zone tesz is the most fundamental lithospheric boundary in europe separating the ancient crust of the fennoscandian shield east european craton from the younger crust of central europe and extending deep into the mantle geophysical potential field images provide an overview of the entire palaeozoic orogenic system of northern and central europe for the first time the tesz is largely concealed by sedimentary basins of permian cenozoic age geological observations are largely restricted to local basement highs and deep boreholes and the coverage of deep seismic surveys is widely spaced despite experiments recently acquired within the europrobe programme by contrast the potential field data offer a relatively detailed coverage of standardised observations throughout the tesz while some features of the images may be sourced in the near surface particularly in the gravity image much of their content reflects the structure of the underlying palaeozoic basement at the scale presented the images highlight the most fundamental features of the crustal structure of the tesz these include the strong contrast between the highly magnetic crust of the east european craton and the less magnetic palaeozoic accreted terranes of central europe the lateral continuity of terranes and their internal structure particularly where arc magmatic complexes are involved and the location and geometry of the terrane boundaries oceanic sutures and strike slip zones that separate them

the sorgenfrei tornquist zone as the mantle edge of baltica lithosphere new evidence from three dimensional seismic anisotropy joint analysis of shear wave splitting parameters and directional dependence of teleseismic p residuals based on data from the seismic experiment tor across the trans european suture zone suggest that the sorgenfrei tornquist zone stz in northern denmark forms the south western margin of baltica in the upper mantle different lithosphere thickness and different orientation of seismic anisotropy in the mantle lithosphere identify three domains separated by the stz between denmark and southern sweden and the thor suture between northern germany and denmark we suggest that the anisotropy reflects frozen in olivine fabrics most probably created during early stages of the evolution of the european continent the middle danish block might represent a microplate caught in between avalonia and baltica before the caledonian orogeny

variscan deformation along the teisseyre tornquist zone in se poland thick skinned structural inheritance or thin skinned thrusting abstract recently acquired seismic reflection data provide better insight in the structural style of extensive sedimentary series overlying the sw slope of the east european craton eec in poland the two main seismic datasets the polcrust 01 profile and polandspan survey yielded contrasting thick and thin skinned structural models for the same structural units in se poland we reattempt an interpretation of the polcrust 01 profile using techniques of cross section balancing and restoration aided by 2d forward seismic modelling an outcome is the thin skinned structural model is this solution relies on a continuous top of the eec crystalline basement well represented in the seismic data as well as on fragmentary yet conclusive seismic geometries in shallow depth intervals proving the ediacaran palaeozoic series to be thrust and folded a variscan late carboniferous compressional regime is consequently invoked to explain thin skinned structuring of the pre permian sedimentary pile and 20 km of calculated shortening we demonstrate an ambiguous nature of the top basement irregularities previously used as indicators of basement rooted vertical faulting the tilt and abrupt increase of the top basement taper under the thin skinned belt are attributed to pre ordovician tectonic processes operating along the sw margin of the eec post rift subsidence and or flexural loading giving rise to a broken foreland plate are invoked

proterozoic and cambrian successions in upper silesia an avalonian terrane in southern poland all cambrian series and several cambrian biozones have been recognized using acritarch biochronology within the siliciclastic successions underlying upper silesia in southern poland the entire cambrian succession is around 580 m thick and contains rare l

structure and kinematics of oblique continental convergence in northern fiordland new zealand abstract southeast of the alpine fault in fiordland new zealand late tertiary faults envelope exposures of early cretaceous high p 12 16 kbar granulite facies orthogneisses these exposures allowed us to examine how pre cenozoic structures influenced variations in the degree and style of kinematic partitioning within a zone of oblique continental convergence fault slip data and kinematic modelling show that oblique slip and reverse displacements preferentially were partitioned east of the alpine fault onto curved ne striking surfaces and moderately dipping 30 52 n and nw striking surfaces respectively approximately 3 0 5 5 km of exhumation and 6 5 7 0 km of oblique dextral displacement occurred on faults that display palm tree style geometries and subhorizontal detachments in profile this heterogeneous style contrasts with the near horizontal slip on subvertical surfaces that define the alpine fault north of milford sound the principal axes of instantaneous strain we determined using faults are compatible with principal stress axes derived from earthquakes our data indicate that mechanical anisotropies created by inherited structures controlled the locations and highly variable geometries of faulting since 7 9 ma the effects of these pre existing structures and a focusing of contractional deformation along the northeast margin of fiordland resulted in an unusually high degree of strike slip partitioning across the southernmost onshore segment of the alpine fault

geophysical constraints on the crustal structure of the east european platform margin and its foreland based on the polcrust 01 deep reflection seismic profile abstract a new 240 km long deep seismic reflection profile polcrust 01 was recently acquired in se poland crossing the east european platform eep margin south east of the north german polish caledonides ngpc here we document geophysical field work and subsequent data processing and modeling results obtained from reflection seismic data are augmented by results of the first arrival tomography applied to co located extended offset refraction data as well as potential field modeling and comparison with the available wide angle reflection refraction data our preferred model of the crustal structure derived by integrating seismic potential field and geological data is composed of crustal blocks terranes separated by nearly vertical faults these are i intact part of the eep ii ysogory terrane iii malopolska terrane and iv carpathian mts with their basement reflective lower crust of the eep can be an inherited feature of crustal extension rifting or compressional tectonics acting at the cratonic margin the teisseyre tornquist zone ttz is depicted as a caledonian transcurrent accretion zone corresponding with the near vertical tomaszow fault bounding the ysogory terrane to the east the crust of the ysogory terrane suggests eep affinity although its middle lower crust thickness is highly reduced the malopolska terrane seems to be internally subdivided into blocks of different magnetic properties of the lower crust the carpathian frontal thrust is associated with a change in the rock properties in the deep basement an unknown crustal block which is not visible in seismic data alone the interpreted structure of the caledonian terranes and their tectonic boundaries favors a transcurrent style of a crustal accretion along the central and se polish segments of the ttz implying a very complex nature of the caledonian accretionary belt of central europe from an array of terranes displaced along the ttz to an accretionary wedge of the collisional ngpc orogen between nw poland and southern north sea area

protolith age of the swakane gneiss north cascades washington evidence of rapid underthrusting of sediments beneath an arc 1 the metamorphic core of the north cascades largely comprises island arc and oceanic terranes juxtaposed prior to circa 96 ma magmatism however the tectonic affinity of the structurally deepest terrane the 9 12 kbar swakane gneiss is distinctly different from other terranes in the core it is not intruded by arc related plutons and contains abundant precambrian zircons new u pb analyses of detrital zircons from the swakane gneiss yield dates from 73 ma to 1610 ma with a dominant late cretaceous population these data indicate that the swakane protolith was deposited as late as 72 5 0 6 ma the 206pb 238u date of the youngest detrital grain following deposition the gneiss was intruded by peraluminous leucogranite sheets that may represent partial melt derived from the gneiss at near to postpeak p t conditions one sheet yielded a u pb crystallization age of 68 36 0 07 ma which indicates that the gneiss was deeply buried within 5 myr of deposition two possible mechanisms considered for this rapid burial 7 mm yr are overthrusting of a forearc or back arc basin by older crystalline rock or underthrusting of trench sediments during low angle subduction the model involving overthrusting of a forearc or back arc basin is most consistent with thermobarometric and isotopic data and the regional geologic setting of the cascades core rapid burial of the swakane protolith is coincident with burial of sediments that formed the pelona orocopia and rand schists of southern california however differences in peak metamorphic temperatures indicate that conditions of burial must have varied along the plate margin

computer simulation of marine ice accretion marine icing can arguably be considered to be the primogenitor of icing problems having occasioned grief to mariners long before aircraft or electrical transmission lines were invented adopting an historical perspective we elucidate the nature of the phenomenon and the scientific and engineering approaches which have been embraced to mitigate it with a view to encouraging other scientists to address this problem we also identify the critical knowledge gaps which stand in the way of a final solution paying particular attention to recent developments and future trends in numerical modelling and wind tunnel experimentation

incipient subduction at the contact with stretched continental crust the puysegur trench a seismic benioff zone and plate kinematics show puysegur trench south of new zealand transitioning to subduction because the local structure and its influence on subduction initiation is poorly understood we conducted a seismic survey with ocean bottom seismometers and multichannel seismic profiles our early results show that the overriding pacific plate beneath the solander basin is composed of block faulted and thinned continental crust and the inner trench wall of northern puysegur ridge is composed of folded and faulted sediment the megathrust interface has been imaged and shows 500 m of downgoing undisturbed sediments combining plate kinematic history with seismic velocity inferred density we show that the density difference across the plate boundary changed as oblique strike slip plate motion juxtaposed dense oceanic crust with thinned continental crust the density difference rapidly increased 18 to 15 ma coincident with subduction initiation suggesting that compositional differences have a large influence on subduction initiation

palaeozoic terranes and their lithospheric boundaries within the trans european suture zone tesz a review the trans european suture zone tesz is a broad and complex zone of terrane accretion separating ancient lithosphere of the baltic shield and east european craton eec from the younger lithosphere of western and southern europe there is debate about the number of terranes involved and their origins the most significant terrane boundaries originally oceanic sutures are poorly exposed and are defined using faunal provinciality prominent geophysical lineaments may represent sub terrane boundaries within composite terranes the avalonia composite terrane was amalgamated to baltica in latest ician time the provenance of the malopolska and moravo silesian terranes whose neoproterozoic basement is suspect with respect to baltica but with which they nonetheless share faunal affinities is still debated the extent of the variscide rhenohercynian zone defines the southern limit of the early palaeozoic accreted terranes terranes within the bohemian massif exhibit hp metamorphism recording subduction driven collision prior to incorporation in the tesz collage itself associated with a hp event in romania the saxothuringian zone and rheic suture are directly juxtaposed with the eec and the crustal structure of the tesz has been much modified by post palaeozoic tectonism deep seismic reflection data where available show that the oceanic sutures are frequently associated with inclined reflectivity zones irz in the lithospheric mantle here inferred to mark relict subduction zones interpreting the age of subduction is complicated by offset of originally coplanar mantle and crustal segments of the irz resulting from early orogenic lithospheric delamination at the moho interface and or post orogenic reordering processes the mantle irz appear to indicate a n directed polarity for early palaeozoic subduction apparently incompatible with the geological evidence which indicates subduction of the tornquist sea beneath avalonia and a large amount of underthrusting of avalonia by baltica possible explanations for these apparently incompatible observations are evaluated

long lasting cadomian magmatic activity along an active northern gondwana margin u pb zircon and sr nd isotopic evidence from the brunovistulian domain eastern bohemian massif manuscript published version available in international journal of earth sciences 2016 doi 10 1007 s00531 016 1416 y

paleomagnetism of ordovician carbonate rocks from malopolska massif holy cross mountains se poland magnetostratigraphic and geotectonic implications abstract the structural and geodynamic history of the malopolska massif holy cross mountains poland situated within the trans european suture zone tesz is still a matter of debate recent provenance studies and biogeographical data indicate that the malopolska is a gondwana derived terrane accreted to baltica between late mid cambrian and tremadocian times existing paleomagnetic data however are equivocal they indicate either close proximity and coherence with baltica since silurian times or a significant variscan dextral strike slip displacement of malopolska with respect to the latter along the teisseyre tornquist line in order to address this problem a detailed paleomagnetic study of a condensed sequence of middle to upper ordovician carbonate rocks from the malopolska massif mojcza quarry has been undertaken samples were taken every 10 to 15 cm through the 4 5 m sequence which covers the upper llanvirnian and caradocian after detailed stepwise thermal demagnetization a high unblocking temperature direction of magnetization with mixed polarities is identified the directions pass the reversal test and yield an overall mean direction of dec 323 inc 63 k 16 6 95 5 8 after bedding correction this corresponds to a paleo south pole of 11 n 46 8 e d p 7 2 d m 9 1 which plots directly on the ordovician segment of the apparent polar wander path for baltica thus rendering major post ordovician rotations of the area relative to baltica unlikely the paleomagnetic results reveal three zones of each reversed r1 r3 and normal polarity n1 n3 the section starts with a reversed polarity interval in the mid llanvirnian stage r1 the transitions from r1 to n1 and from n1 to r2 in middle llanvirnian and from r2 to n2 during upper llanvirnian correspond well with previous paleomagnetic results based on graptolite biostratigraphy after a short normal polarity interval n2 the lower caradocian is dominated by inverse polarity r3 the following transition from r3 to n3 falls in the upper part of the amorphognathus tvaerensis conodont zone for this polarity change the misfit between the magnetostratigraphy of the mojcza section and previously published paleomagnetic results most likely reflects uncertainties of correlating between conodont and graptolite stratigraphies

thermal maturation of the lower palaeozoic strata in the southwestern margin of the malopolska massif southern poland no evidence for caledonian regional metamorphism conodont colour alteration index cai values have been used for the assessment of the thermal history of lower palaeozoic strata in the southwestern margin of the malopolska massif along the contact with the upper silesian massif the cai data provide no evidence for a previously suggested greenschistgrade regional metamorphism in the cracow myszkow zone during the caledonian epoch near zarki the silurian rocks display a relatively uniform thermal overprint cai values of 4 resulting from sedimentary burial during the early late carboniferous the estimated maximum temperatures of 200 220 c can be explained by an elevated heat flow associated with the cracow fault system this thermal maturation level was locally enhanced cai values up to 8 after the westphalian due to the magmatic activity caused by the variscan regional extension

deducing the ancestry of terranes shrimp evidence for south america derived gondwana fragments in central europe we present here an example of how the sensitive high resolution ion microprobe shrimp zircon dating method can provide a terrane specific geochronological fingerprint for a rock and thus help to reveal major tectonic boundaries within orogens this method applied to inherited zircons in a ca 580 ma metagranitoid rock from the eastern bohemian massif has provided for the first time in the central european variscan basement unequivocal evidence for mesoproterozoic and late paleoproterozoic geologic events ca 1 2 ga 1 5 ga and 1 65 1 8 ga the recognition of such zircon ages has important consequences because it implies that parts of the precambrian section of variscan central europe were originally derived from a grenvillian cratonic province as opposed to the common assumption of an african connection a comparison with previously published shrimp data suggests however that these mesoproterozoic and late paleoproterozoic zircon ages may be restricted to the moravo silesian unit in the eastern variscides whereas the saxothuringian and moldanubian zones appear to contain a typical north african i e neoproterozoic plus eburnian inherited zircon age spectrum this finding supports new tectonic concepts according to which variscan europe is composed of a number of completely unrelated terranes with extremely different paleogeographic origins the moravo silesian unit can be best interpreted as a peri gondwana terrane which was situated in the realm of the amazonian cratonic province by the late precambrian comparable to the avalonian terranes of north america and the united kingdom

gondwana derived microcontinents the constituents of the variscan and alpine collisional orogens abstract the european variscan and alpine mountain chains are collisional orogens and are built up of pre variscan building blocks which in most cases originated at the gondwana margin such pre variscan elements were part of a pre ordovician archipelago like continental ribbon in the former eastern prolongation of avalonia and their present day distribution resulted from juxtaposition through variscan and or alpine tectonic evolution the well known nomenclatures applied to these mountain chains are the mirror of variscan resp alpine organization it is the aim of this paper to present a terminology taking into account their pre variscan evolution at the gondwana margin they may contain relics of volcanic islands with pieces of cadomian crust relics of volcanic arc settings and accretionary wedges which were separated from gondwana by initial stages of rheic ocean opening after a short lived ordovician orogenic event and amalgamation of these elements at the gondwanan margin the still continuing gondwana directed subduction triggered the formation of ordovician al rich granitoids and the latest ordovician opening of palaeo tethys an example from the alps external massifs illustrates the gradual reworking of gondwana derived pre variscan elements during the variscan and alpine tertiary orogenic cycles

the effect of pre tectonic reaction and annealing extent on behaviour during subsequent deformation insights from paired shear zones in the lower crust of fiordland new zealand granulite facies pargasite orthogneiss is partially to completely reacted to garnet granulite either side of narrow 20 mm felsic dykes in fiordland new zealand forming 10 80 mm wide garnet reaction zones the metamorphic reaction changed the abundance of minerals and their shape and grain size distribution the extent of reaction and annealing temperature related coarsening and nucleation is greatest close to the dykes whereas further away the reaction is incomplete as a consequence grain size and the abundance of garnet decreases away from the felsic dykes over a few centimetres the aspect ratios of clusters of s1 pyroxene and pargasite in the orthogneiss which are variably reacted to post s1 garnet decrease from high in the host to near equidimensional close to the dyke post reaction deformation localized in the fine grained partially reacted areas this produced a pattern of paired shear zones located at the outer parts of the garnet reaction zone our study shows that grain size sensitive deformation occurs where the grain size is sufficiently reduced by metamorphic reaction the weakening of the rock due to the change in grain size distribution outweighs the addition of nominally stronger garnet to the assemblage

magmatic activity at the silurian devonian boundary in the brunovistulia and malopolska terranes s poland possible link with the rheic ocean closure and the onset of the rheno hercynian basin the age of granophyric diorite from the sosnowiec ig 1 borehole brunovistulia terrane was studied by means of u pb single grain zircon analysis performed on a shrimp sensitive high resolution ion microprobe iie device the isotope ages and provenance of zircons from the emsian tuffs cropping out in the southern part of the holy cross mountains malopolska terrane were also investigated using the same method the age of the diorite intrusion 420 2 ma is comparable with the combined ar ar magnetostratigraphic age of the bardo diabase intrusion from the northern part of the malopolska terrane these intrusions were emplaced during the same event of regional tectonic extension associated with the rheic ocean closure and the onset of processes creating the rheno hecynian basin near the silurian devonian boundary a negative nb anomaly characteristic of both intrusions could be linked with the subduction of the rheic oceanic crust under the se margin of the old red continent emsian magmatic activity in the distant rheno hercynian zone provided several tuff layers in the northern part of the malopolska terrane as can be inferred from zircon ages these tuffs were derived from mafic eruptions that cut sedimentary rocks containing detrital zircons transported from baltica this interpretation fits the existing models of development of the rheno hercynian basin in the emsian

plumbotectonic aspects of polymetallic vein mineralization in paleozoic sediments and proterozoic basement of moravia czech republic a regional isotopic study of pb and s in hydrothermal galenas and u pb and s in potential source rocks was carried out for part of moravia czech republic two major generations of veins syn variscan and post variscan are defined based on the pb isotope system together with structural constraints local structures and regional trends the pb isotopic compositions of galena plot in two distinct populations with outliers in 206pb 204pb 207pb 204pb space galena from veins hosted in greywackes provides a cluster with the lowest pb pb ratios 206pb 204pb 18 15 18 27 207pb 204pb 15 59 15 61 208pb 204pb 38 11 38 23 those hosted in both limestones and greywackes provide the second cluster 206pb 204pb 18 37 18 44 207pb 204pb 15 60 15 63 208pb 204pb 38 14 38 32 these clusters suggest model pb ages as early carboniferous and triassic jurassic the latter associated with mvt like deposits two samples from veins hosted in proterozoic rocks lie outside the two clusters in metagranitoid 206pb 204pb 18 55 207pb 204pb 15 64 208pb 204pb 38 29 and in orthogneiss 206pb 204pb 18 79 207pb 204pb 15 73 208pb 204pb 38 54 the results from these two samples suggest an interaction of mineralizing fluids with the radiogenic pb rich source basement the values of 34s suggest the paleozoic host rocks mostly 6 7 to 5 2 cdt as the source of s for hydrothermal sulfides mostly 4 8 to 2 5 cdt u pb data and pb isotope evolutionary curves indicate that late devonian and early carboniferous sediments especially siliciclastics are the general dominant contributor of pb for galena mineralization developed in sedimentary rocks plumbotectonic mixing occurred it is deduced only between the lower and the upper crust the latter involving proterozoic basement containing heterogeneous radiogenic pb without any significant input from the mantle it is concluded that in the moravo silesian and rhenohercynian zones including proximal districts in poland lead and sulfur have been mobilized from the adjacent rocks during multiple hydrothermal events in processes that are remarkably comparable in timing geochemistry of fluids and nature of sources

strengths and limitations of zircon lu hf and o isotopes in modelling crustal growth abstract the robust nature of the mineral zircon combined with our analytical ability to readily acquire in situ uranium lead u pb lutetium hafnium lu hf and oxygen o isotopic data has resulted in a rapid rise in the use of zircon isotopic datasets for studying both the generation of continental crust and its growth through earth history in such studies there has been a strong focus on developing methods to determine the timing and or proportion of juvenile magmatic addition to the continental crust one widespread approach to determine the timing of crustal growth has been the construction or fitting of reworking arrays to regional hf isotopic datasets simple stochastic models are presented which highlight that in many cases apparent reworking arrays are much more likely to represent a process of on going dilution and refertilisation of ancient crust consistent with hot zone models of granitoid generation and the need to refertilise lower crustal reservoirs to maintain magmatism a new compilation of magmatic rock zircon lu hf and o isotope data is used to demonstrate that the use of mantle like o isotope data as a screening tool for meaningful hf model ages is also unlikely to be reliable with independently constrained data indicating that as few as 14 of hf model ages provide a meaningful indicator of the timing of crustal growth the limitations of hf model ages are discussed with regard to existing approaches for continental growth and we demonstrate that popular inverse modelling approaches suffer from a bias created by both the use of model ages and numerical artefacts in an effort to address some of the limitations within existing models we develop stochastic models based on joint calibration of multiple datasets which allow for more unique solutions

cambrian palaeomagnetic data from baltica implications for true polar wander and cambrian palaeogeography a reliable early cambrian c 535 ma and a preliminary late cambrian c 500 ma palaeomagnetic pole from baltica sweden overlap within uncertainty and they are also broadly compatible with vendian c 583 ma palaeomagnetic data apparent polar wander for baltica amounts to less than 25 between 583 and 500 ma and therefore negates recent speculations that the earth tipped 90 during the early cambrian true polar wander throughout vendian and cambrian times baltica lay at southerly latitudes c 30 60 s baltica was geographically inverted and present day northern baltica faced the nw margin of gondwana which covered the south pole laurentia eastern baltica and laurentia west gondwana were separated by the iapetus ocean while the aegir sea separated western baltica from the taimyr region of siberia during the cambrian baltica probably moved eastward along the gondwana margin and by c 515 520 ma subduction in the aegir sea was initiated a major event is recognized in late cambrian or early ordovician times c 500 478 ma when baltica must have undergone a 55 counter clockwise rotation in c 22 million years 3 ma we relate this to the early caledonian finnmarkian orogeny which involved arc continent collision following subduction

the ordovician history of the iapetus ocean in britain new palaeomagnetic constraints new late tremadoc early arenig palaeomagnetic results from sw wales imply that s britain part of eastern avalonia occupied a southerly latitude of c 60 s in early ordovician times when combined with scottish ordoviaan palaneomagnetic data which indicate a 15 s latitude the results indicate that the british sector of the iapetus ocean reached n latitudinal width of c 5000 km in tremadoc arenig times which was reduced to c 3000 km by llanvirn llandeilo mid ordovician times the new data resolve two previous controversies in palaeozoic palaeogeography first the high southerly palaeolatitude links avdonia to gondwana marginal to w africa thus reconciling codlicting reconstructions based upon either palaeomagnetic or faunal facies evidence alone second reliable llanvim palaeomagnetic data imply that avlonia had rifted northwards by arenig time whereas armorica remained proximal to northern africa throughout the ordovician the combined data therefore establish that avdonia and armorica formed separate micro continents when rifting from gondwana

cretaceous high p granulites at milford sound new zealand metamorphic history and emplacement in a convergent margin setting granulite facies orthogneiss of the arthur river complex arc at milford sound western fiordland records a complex early cretaceous magmatic and orogenic history for the pacific gondwana margin that culminated in the emplacement and burial of a dioritic batholith the western fiordland orthogneiss wfo enstatite bearing mafic to intermediate protoliths of the arc and wfo intruded the middle to upper crust the early deformation history of the arc is preserved in the pembroke granulite where two pyroxene s1 assemblages that reflect p 750 c were only patchily recrystallized during later deformation s1 is cut by garnet bearing leucogabbroic to dioritic veins which are cut by distinctive d2 fractures involving anorthositic veins and garnet diopside plagioclase bearing reaction zones these zones are widespread in the arc and wfo and record conditions of p 14 kbar and t 750 c garnet clinopyroxene bearing corona reaction textures that mantle enstatite in both the arc and wfo reflect early cretaceous burial by approximately 25 km of continental crust most of the arc is formed from the milford and harrison gneisses which contain steeply dipping s4 assemblages that envelop the pembroke granulite and involve garnet hornblende diopside clinozoisite rutile and plagio clase with or without kyanite the p t history of rocks in western fiordland reflects pronounced early cretaceous convergence related tectonism and burial possibly related to the collision and accretion of island arc material onto the pacific gondwana margin

direct observation of adakite melts generated in the lower continental crust fiordland new zealand adakites have a distinct chemistry that links them to melting of a mafic source at high pressure they have been attributed to melting of subducted oceanic crust or melting of the mafic crustal roots of thick continental arcs and are an important contrast to mantle wedge melting as a means of generating continental crust we report the first direct evidence for the generation of adakitic melts in mafic lower continental crust in an exhumed cretaceous arc in the south island of new zealand the lower crustal pembroke granulite has the bulk chemistry and partial melting textures involving peritectic garnet appropriate for a source region for an adakitic melt the melt migrated from the area through a fracture network now filled with trondhjemitic veins emplacement of the melt was in the upper crust of the cretaceous section illustrated by the presence of coeval adakites in the upper crustal nelson westland region

transcurrent nature of the teisseyre tornquist zone in central europe results of the polcrust 01 deep reflection seismic profile teisseyre tornquist zone ttz corresponds to a crustal boundary between the precambrian east european platform eep and the palaeozoic west european platform although the zone has been controlling phanerozoic evolution of large parts of central europe its course geometry and origin are still poorly constrained deep reflection seismic profile polcrust 01 recently acquired in se poland for the first time allowed a precise comparison of the ediacaran and later tectonic patterns to the deep crustal features of the ttz and adjacent areas the ttz corresponds to the subvertical tomaszow fault separating the radom kra nik elevation composed of the typical eep crust from the bilgoraj narol block bnb in the sw with a thinned crystalline basement showing affinities to the eep crust the bnb is a part of the larger caledonian ysogory terrane as evidenced by its lower palaeozoic stratigraphy and gravity data thus for the first time the proximal baltican affinity of this unit has been documented unambiguously the ysogory terrane is delimited from the sw by the subvertical cieszanow fault zone corresponding to the holy cross suture the adjacent malopolska terrane is characterized by a distinct early palaeozoic stratigraphy and lower middle crust exhibiting sw dipping reflective packages interpreted as ne verging thrust and shear zones of a neoproterozoic orogen the observations from the polcrust 01 profile and regional comparisons indicate that the ttz is a major caledonian transcurrent zone between poland and east romania in central poland the ttz likely forms a narrow subvertical contact between the eep and a proximal kuiavia terrane as constrained by the deep refraction seismic data to the nw the zone extends towards the pomeranian part of the caledonide fold and thrust belt related to the avalonia baltica collision zone thor suture south east of poland the ttz corresponds to the rava ruska fault zone established as a caledonian suture separating adjacent terrane probably of a baltican affinity the east romanian part of the ttz conforms with the sf ntu gheorghe fault separating reworked eep crust of the pre dobrogean depression from the north dobrogea unit bearing a strong variscan and cimmerian overprint

fingerprinting gondwana versus baltica provenance nd and sr isotopes in lower paleozoic clastic rocks of the malopolska and łysogory terranes southern poland abstract neodymium and strontium isotope compositions of clastic material in lower paleozoic rocks in addition to detrital zircon and mica geochronology and faunal data are used to constrain the geotectonic provenance of the malopolska and ysogory terranes in southern poland being characterized by markedly different geological histories during early paleozoic times malopolska and ysogory were most often interpreted as exotic terranes but their identity provenance and accretionary history are still being discussed this study presents the first systematic nd and sr isotope survey of the lower paleozoic siliciclastic rocks cambrian clastic rocks of malopolska differ in their nd and sr isotope compositions from those of ysogory the former are characterized by a wide range of the end 505 ma values from 11 7 to 5 7 sr isotope ratios from 0 712 to 0 767 and model ages t2dm predominantly younger than 1 9 ga whereas the end t values of the latter vary within a fairly narrow range of the end 505 ma from 11 0 to 8 3 sr isotope ratios from 0 722 to 0 754 and model ages are older than 1 9 ga new nd data combined with detrital zircon ages provide evidence that malopolska must have been supplied with clastic material from amazonian sources during cambrian times being also progressively sourced from the baltic svecofennian crust in the middle cambrian detritus recognized in ysogory has mostly been derived from the svecofennian basement of fennoscandia but it has also a small addition from cadomian sources all provenance and biogeographic data suggest that malopolska was situated close to the amazonian craton near the western end of the cadomian belt during the early cambrian and it was not until the late middle cambrian that malopolska collided with the baltica margin during the late cambrian ysogory occupied a position between baltica and the cadomian belt but it was probably not yet accreted to the baltic crust at that time

late neoproterozoic to early palaeozoic palaoegeography of the holy cross mountains central europe an integrated approach study of geochemistry examination of isotope ages of detrital minerals palaeomagnetic analysis and a study of the trilobites were performed to provide constraints on the palaeogeographical position of the holy cross mountains in late ediacaran early palaeozoic time the geochemical results indicate an active continental margin or continental island arc provenance of the ediacaran sediments sediments from a passive continental margin were deposited here during the cambrian and ordovician the palaeomagnetic pole isolated from cambrian rocks of the malopolska region of the holy cross mountains corresponds to the cambrian segment of the baltic apparent polar wander path isotope age estimations indicate that cambrian sediments of the malopolska region contain detritus not only from a latest neoproterozoic source but also from sources with ages of c 0 8 0 9 ga 1 5 ga and 1 8 ga the malopolska brunosilesia dobrugea and moesia terranes which originally developed near the present southern edge of baltica and were partly involved in the cadomian orogen were dextrally relocated along its trans european suture zone margin the first stage of this movement took place as early as latest ediacaran time while baltica rotated anticlockwise anticlockwise rotation of baltica at the cambrian ordovician boundary implies further dextral movement of the malopolska block

the east carpathian crystalline mesozoic zone romania paleozoic amalgamation of gondwana and east european craton derived terranes abstract the alpine orogen of the eastern carpathians contains pre alpine terranes framed by younger rocks the geological data on these terranes are reviewed and interpreted in order to elucidate their geodynamic evolution during the paleozoic the rebra tulghes terrane shows a stratigraphic sequence similar to avalonia neoproterozoic platformal metasediments rebra group overlain by late neoproterozoic volcano sedimentary rocks pietrosu bistritei porphyroids and lower paleozoic cover tulghes group the bretila terrane made up of orthogneisses pelitic gneisses granites amphibolites and micaschists shows affinities with the basement of the east european craton the modern juxtaposition of the bretila terrane and the rebra tulghes terrane may be explained in terms of collision between the latter and the east european craton during the ordovician times as an effect of collision the bretila terrane was thrust over the rebra tulghes terrane and induced the occurrence of thrust faults within it a lower paleozoic emplacement of the east carpathian pre alpine thrust nappes is thus inferred

crustal structure at the easternmost termination of the variscan belt based on celebration 2000 and alp 2002 data abstract the eastern margin of the variscan belt in europe comprises plate boundaries between continental blocks and terranes formed during different tectonic events the crustal structure of that complicated area was studied using the data of the international refraction experiments celebration 2000 and alp 2002 the seismic data were acquired along sw ne oriented refraction and wide angle reflection profiles cel10 and alp04 starting in the eastern alps passing through the moravo silesian zone of the bohemian massif and the fore sudetic monocline and terminating in the tesz in poland the data were interpreted by seismic tomographic inversion and by 2 d trial and error forward modelling of the p waves velocity models determine different types of the crust mantle transition reflecting variable crustal thickness and delimiting contacts of tectonic units in depth in the alpine area few km thick lvz with the vp of 5 1 km s 1 dipping to the sw and outcropping at the surface represents the molasse and helvetic flysch sediments overthrust by the northern calcareous alps with higher velocities in the bohemian massif lower velocities in the range of 5 0 5 6 km s 1 down to a depth of 5 km might represent the se termination of the elbe fault zone the fore sudetic monocline and the tesz are covered by sediments with the velocities in the range of 3 6 5 5 km s 1 to the maximum depth of 15 km beneath the mid polish trough the moho in the eastern alps is dipping to the sw reaching the depth of 43 45 km the lower crust at the eastern margin of the bohemian massif is characterized by elevated velocities and high vp gradient which seems to be a characteristic feature of the moravo silesian slightly different properties in the moravian and silesian units might be attributed to varying distances of the profile from the moldanubian thrust front as well as a different type of contact of the brunia with the moldanubian and its northern root sector the moho beneath the fore sudetic monocline is the most pronounced and is interpreted as the first order discontinuity at a depth of 30 km

tracking the influence of a continental margin on growth of a magmatic arc fiordland new zealand using thermobarometry thermochronology and zircon u pb and hf isotopes 1 geothermobarometric radiogenic isotopic and thermochronologic data are used to track the influence of an ancient continental margin western province on development of an adjacent carboniferous cretaceous magmatic arc outboard median batholith in fiordland new zealand the data show a record of complicated mesozoic gondwana margin growth paragneiss within the outboard median batholith is of carboniferous to jurassic age and records burial to middle crustal depths in late jurassic early cretaceous during subduction related plutonism and arc thickening in contrast western province metasedimentary rocks in the area of study immediately west of the outboard median batholith are late cambrian early ordovician in age recrystallized at the amphibolite facies in the late devonian early carboniferous and exhibit no evidence for mesozoic textural or isotopic reequilibration a phase of deformation between 128 and 116 ma deformed exhumed and cooled the outboard median batholith to greenschist facies temperatures while large parts of the western province underwent 9 kbar metamorphic conditions zircon grains from mesozoic inboard plutons are isotopically more evolved hf t 2 3 to 4 0 than those in the outboard median batholith hf t 9 4 to 11 1 the contrasting zircon hf isotope ratios absence of s type plutons or proterozoic early paleozoic inherited zircon and the apparent absence of early paleozoic metasedimentary rocks indicates that the outboard median batholith is unlikely to be underlain by the western province continental lithosphere the new data are consistent with the outboard median batholith representing an allochthonous although not necessarily exotic arc that was juxtaposed onto the gondwana continental margin along the intervening grebe mylonite zone

the baltica gondwana suture in central europe evidence from k ar ages of detrital muscovites and biogeographical data

early cambrian location and affinities of the brunovistulian terrane central europe in the light of palaeomagnetic data the brunovistulian was one of the first tectonic units of central europe to be defined as a terrane in spite of extensive studies the early palaeozoic palaeogeographical position and provenance of this unit remains unclear a palaeomagnetic study of the lower cambrian red beds and a study of the trilobite fauna were performed to provide constraints on the palaeogeographical position of the terrane in early cambrian time good quality palaeomagnetic data obtained from the lower cambrian red beds suggest the mixed nature of the early cambrian geomagnetic field and a nearly equatorial position a palaeolatitude of c 7 of the brunovistulian terrane in the early cambrian comparison of this palaeolatitude with existing palaeogeographical models leads to the conclusion that at this time the brunovistulian terrane was separated by a great distance from the avalonian margin of gondwana the terrane was located within the cadomian belt occupying a position north of the present day northern margin of africa it was coupled to the present day southern margin of baltica during the cambrian when baltica moved along the cadomian margin of gondwana another possibility is that the brunovistulian terrane could have remained near this margin of baltica since grenvillian time and was incorporated into the cadomian orogen

the mafic layered complex of the kabye massif north togo and north benin evidence of a pan african granulitic continental arc root abstract between the predominantly neoarchean paleoproterozoic west african craton wac and the saharian metacraton smc the dahomeyides suture zone represents a valuable witness of continental amalgamation during pan african times in the kabye massif northern togo and northern benin mainly granulitic metagabbros associated with al rich kyanite and garnet bearing felsic dykes are exposed as tectonic lenses within the pre pan african gneisses of the smc new geochemical data suggest that the high grade rocks granulites in the kabye massif originated in a mature continental arc setting afc calculations constrain the amount of contamination of mantle wedge derived magmas by crustal metasediments to about 10 reconstruction of initial magmatic stratigraphy has been carried out using cipw norms for cumulitic sequences within the massif indicating a normal igneous polarity from west to east published geochemical signatures along the pan african suture zone of the dahomeyides in ghana togo and benin constrain the origin of mafic granulitic and eclogitic complexes a distinction is made between bodies with mainly morb signatures originated from the subducted wac plate passive margin and those with magmatic arc signatures originated from the over riding plate mantle wedge this suggests that the closure of the oceanic domain between the wac and the smc from 640 to 610 ma was mainly accommodated by oceanic subduction beneath the active continental margin before pan african collision

principal characteristics of the upper silesian block and malopolska block border zone southern poland the upper silesian and malopolska blocks are situated near the southwestern boundary of the east european platform within the trans european suture zone the lower palaeozoic lithologies of the blocks reveal different stratigraphic and diastrophic development in the upper silesian block unmetamorphosed and gently folded lower cambrian to ordovician sedimentary rocks rest on a cadomian basement the lower cambrian is represented by an older sub holmia borzeta formation and a younger holmia goczalkowice formation the thickness of the cambrian lithologies increases from the southwest towards the lateral part of the block in the malopolska block palaeozoic and precambrian lithologies are represented by regionally metamorphosed and intensely folded lower cambrian vendian clastic rocks which are unconformably overlain by ordovician lower silurian carbonates and upper silurian clastic rocks the crystalline basement of the malopolska block has yet to be recognized the lower palaeozoic sediments of both blocks are overlain by devonian and carboniferous rocks the blocks are in direct contact along a narrow tectonic zone a part of the largely concealed hamburg krakow fault zone in which tectonic evolution has taken place spasmodically with strike slip movements predominating

p t evolution of a variscan lower crustal segment a study of granulites from the schwarzwald germany pressure temperature time p t t paths of orogenic granulites introduction provide important information on the thermal and chemical structure general background of the lower continental crust through time and constraints on tectonic granulites are typical rocks of the earth s middle to processes we present the first detailed petrological investigation of lower crust under high temperature conditions they are granulites from the variscan schwarzwald pelitic granulites from the found as xenoliths in basaltic volcanic rocks mainly central schwarzwald gneiss complex csgc are characterized by within continental rifts but most granulites occur as the peak assemblage garnet rutile kyanite antiperthite complexes or terranes in orogenic settings orogenic quartz felsic to intermediate granulites from the southern granulites display a wide compositional range harley schwarzwald gneiss complex ssgc exhibit different peak as1989 1998 and are known from a variety of collisional semblages with clinopyroxene orthopyroxene ternary feldspar garnet belts that formed during different episodes since the quartz and sillimanite and manifold retrograde reaction textures archaean e g harley 1998 clarke et al 2000 moller peak p t conditions were calculated by two feldspar thermometry et al 2000 determination of bulk rock and mineral garnet orthopyroxene thermometry and various geobarometers minicompositions calculation of peak equilibration conmum estimates for peak conditions are 950 1010 c and 1 4 1 8 ditions and dating of orogenic granulites thus provide us gpa for the granulites of the csgc which followed a clockwise with important constraints on the thermal and chemical p t path the retrograde path is characterized by initial isothermal structure of the earth s continental crust at different decompression associated with partial melting followed by isobaric geological times cooling peak conditions for the ssgc are 1015 c and 1 5 gpa harley 1989 showed that equilibration conditions minimum temperature maximum pressure no prograde relics are deduced from natural orogenic granulites cover a wide preserved and isothermal decompression was less pronounced than range in particular pressures are highly variable and in the csgc other variscan hp ht granulites from central the granulite field may be divided into a low pressure europe show similar lithologies equilibration temperatures and lp a medium pressure mp and a high pressure hp ages 340 335 ma the heat for widespread high temperature facies according to green ringwood 1967 peak metamorphism in the variscan lower crust could have been supplied temperatures of many granulite terranes scatter around by repeated intrusion of subduction related basic magmas rapid 800 c bohlen 1987 but an increasing number of near isothermal decompression of the granulites may have been ultra high temperature uht granulite complexes facilitated by considerable volumes of partial melt and by orogenic extension 900 1100 c and 0 7 1 3 gpa harley 1998 are being recognized e g harley hensen 1990 dasgupta et al 1995 klemd brocker 1999 hokada 2001 regarding retrograde p t paths harley 1989 distinguished two

crustal structure seismic anisotropy and deformations of the ediacaran cambrian of the malopolska block in se poland based on data from two seismic wide angle experiments the area of se poland represents a complex contact of tectonic units of different consolidation age from the precambrian east european craton through palaeozoic west european platform including malopolska block to cenozoic carpathians and carpathian foredeep in order to investigate the anisotropic properties of the upper crust of the malopolska block and their relation to tectonic evolution of the area two seismic datasets were used seismic wide angle off line recordings from polcrust 01 deep seismic reflection profile and recordings from active deep seismic experiment celebration 2000 during acquisition of deep reflection seismic profile polcrust 01 in 2010 a 35 km long line of 14 recorders pa 14 oriented perpendicularly to the profile was deployed to record the refractions from the upper crust pg at wide range of azimuths these data were used for an analysis of the azimuthal anisotropy of the mb with the modified delay time inversion method the results of modelling of the off line refractions from the mb suggest 6 hti anisotropy of the cambrian ediacaran basement with 130o azimuth of the fast velocity axis and mean vp of 4 9 km s to compare this result with previous independent information about anisotropy at larger depth a subset of previously modelled data from celebration 2000 experiment recorded in the mb area was also analysed by inversion the recordings of pg phase at up to 120 km offsets were analysed using anisotropic delay time inversion providing information down to 12 km depth the celebration 2000 model shows 9 hti anisotropy with 126o orientation of the fast axis thus local scale anisotropy of this part of mb confirms the large scale anisotropy suggested by previous studies based on data from a broader area and larger depth interval the azimuthal anisotropy i e hti symmetry of the medium is interpreted as a result of strong compressional deformation during the accretion of terranes to the eec margin leading to tight sub vertical folding and fracturing of intrinsically anisotropic metasediments forming the mb basement obtained anisotropy models are compared with data about stratal dips of the mb sequences and implications of assuming more realistic tti model are discussed wide angle recordings from off line measurements along a reflection profile provided new information about seismic velocity and anisotropy not available from standard near vertical profiling and contributed to more complete image of the upper crustal structure of malopolska block

age and origin of the well preserved organic matter in internal sediments from the silesian cracow lead zinc deposits southern poland the molecular and petrographic characteristics of organic matter in internal sediments from the mississippi valley type lead zinc deposits in southern poland reveal immature and well preserved organic matter huminite reflectance values of organic matter in all internal sediments are low with a mean value of 0 29 corresponding to a lignite range of coalification most organic compounds in the organic matter e g cadalene retene simonellite perylene and sitosterol and its transformation products stigmastanol and stigmasta 3 5 dien one as well as lignin degradation compound products e g benzoic acid vanillin 4 benzaldehyde benzenedicarboxilic acids and hydroxybenzoic acids are of terrestrial origin monosaccharides with dominant and glucose were identified as possible remnants of cellulose degradation products suggesting an excellent state of organic matter preservation given that monosaccharides are preserved only under conditions of limited oxygen after sedimentation resulting from the rapid accumulation of internal sediments in meteoric paleokarst cavities followed by insignificant diagenesis petrologic and palynological data on internal sediments clearly indicate a middle triassic age for organic matter and for the development of a triassic meteoric karst system immediately after anisian carbonate sedimentation

transformation of two pyroxene hornblende granulite to garnet granulite involving simultaneous melting and fracturing of the lower crust fiordland new zealand granulite facies gabbroic and dioritic gneisses in the pembroke valley milford sound new zealand are cut by vertical and planar garnet reaction zones in rectilinear patterns in gabbroic gneiss narrow dykes of anorthositic leucosome are surrounded by fine grained garnet granulite that replaced the host two pyroxene hornblende granulite at conditions of 750 uc and 14 kbar major and trace element whole rock geochemical data indicate that recrystallization was mostly isochemical the anorthositic veins cut contacts between gabbroic gneiss and dioritic gneiss but change in morphology at the contacts from the anorthositic vein surrounded by a garnet granulite reaction zone in the gabbroic gneiss to zones with a septum of coarse grained garnet surrounded by anorthositic leucosome in the dioritic gneiss the dioritic gneiss also contains isolated garnet grains enclosed by leucosome and short planar trains of garnet grains linked by leucosome partial melting of the dioritic gneiss mostly controlled by hornblende breakdown at water undersaturated conditions is inferred to have generated the leucosomes the form of the leucosomes is consistent with melt segregation and transport aided by fracture propagation limited retrogression suggests considerable melt escape dyking and melt escape from the dioritic gneiss are inferred to have propagated fractures into the gabbroic gneiss the migrating melt scavenged water from the surrounding gabbroic gneiss and induced the limited replacement by garnet granulite

three dimensional seismic modelling of the crustal structure between east european craton and the carpathians in se poland based on celebration 2000 data summary in this paper we present results of 3 d first arrival tomography applied to data recorded in se poland during the celebration 2000 seismic experiment the target area covers ca 500 500 km 2 and represents a complex geological setting from old precambrian platform east european craton eec through the crustal blocks terranes that form the transeuropean suture zone tesz to the young alpine orogen the carpathians contrasting velocity distributions in various geological units makes the tomographic inversion challenging for this reason much attention was paid to the inversion methodology we tested multioffset and multiscale approaches by increasing the offset range in the multioffset inversion we have independently constrained different depth ranges of our model we have found that the multiscale method that is the gradual stepping from bigger to smaller model cells produced the preferred solution resolution of the resultant crustal model was determined by performing checkerboard and restoration resolution tests lateral resolution of the order of 25 km is inferred down to 10 km depth and 50 km down to 25 30 km depth we have also applied a quasi monte carlo analysis to determine the absolute errors of model parameters which to our knowledge is the first such attempt in case of a 3 d wide angle data set the mean uncertainties of our tomographic velocities are 0 1 km s 1 but some anomalies are recovered with

seismic and geological structure of the crust in the transition from baltica to palaeozoic europe in se poland celebration 2000 experiment profile cel02 abstract the celebration 2000 together with the earlier polonaise 97 deep seismic sounding experiments was aimed at the recognition of crustal structure in the border zone between the precambrian east european craton baltica and palaeozoic europe the cel02 profile of the celebration family is a 400 km long sw ne transect running in poland from the upper silesia block usb across the malopolska block mb and the trans european suture zone tesz to the east european craton eec the structure along cel02 was interpreted using both 2d tomography and forward ray tracing techniques as well as 2d gravity modelling the crustal thickness along cel02 varies from 32 35 km in the usb to 45 47 km beneath the tesz and the eec the usb is a clearly distinctive crustal block with the characteristic high velocity lower crust 7 1 7 2 km s interpreted as a fragment of gondwana the krakow lubliniec fault is a terrane boundary produced by soft docking of the usb with the mb the malopolska crust fundamentally differs from the usb and has a strong connection with baltica it is a transitional 150 to 200 km wide unit composed of the extended baltican lower crust and the overlying low velocity 5 15 5 9 km s neoproterozoic metasediments in the up to 18 km thick upper crust the ysogory unit has its crustal structure identical with that of malopolska thus it is connected with baltica and cannot be interpreted as a gondwana derived terrane higher velocity and density bodies found below the mazovia lublin graben at a depth of 12 km and at the base of the lower crust might be a result of mantle derived mafic intrusions accompanying the extension of baltica by the preliminary 2d gravity modelling we have reconfirmed the need for considering the increased tesz mantle density in comparison to the eec and usb mantle

brunovistulian terrane bohemian massif central europe from late proterozoic to late paleozoic a review the brunovistulian terrane represents a microcontinent of enigmatic proterozoic provenance that was located at the southern margin of baltica in the early paleozoic during the variscan orogeny it represented the lower plate at the southern margin of laurussia involved in the collision with the armorican terrane assemblage in this respect it resembles the avalonian terrane in the west and the istanbul zone in the east there is a growing evidence about the presence of a devonian back arc at the margin of the brunovistulian terrane the early variscan phase was characterized by the formation of devonian extensional basins with the within plate volcanic activity and formation of narrow segments of oceanic crust the oldest visean flysch of the rheic rhenohercynian remnant basin protivanov andelska hora and horni benesov formations forms the highest allochthonous units and contains together with slices of silurian bohemian facies clastic micas from early paleozoic crystalline rocks that are presumably derived from terranes of armorican affinity although provenance from an active brunovistulian margin cannot be fully excluded either the development of the moravo silesian late paleozoic basin was terminated by coal bearing paralic and limnic sediments the progressive carboniferous stacking of nappes and their impingement on the laurussian foreland led to crustal thickening and shortening and a number of distinct deformational and folding events the postorogenic extension led to the formation of the terminal carboniferous early permian boskovice graben located in the eastern part of the brunovistulian terrane in front of the crystalline nappes the highest allochthonous westernmost flysch units locally with the basal slices of the devonian and silurian rocks thrusted over the silesicum in the nw part of the brunovistulian terrane may share a similar tectonic position with the giessen harz nappes the silesicum represents the outermost margin of the brunovistulian terrane with many features in common with the northern phyllite zone at the avalonia armorica interface in germany

tectonic evolution of the upper allochthon of the ordenes complex northwestern iberian massif structural constraints to a polyorogenic peri gondwanan terrane the upper allochthon of northwest iberia represents the most exotic terrane of this part of the european variscan belt recent advances in the metamorphic petrology structural geology and geochronology of the upper allochthon in the ordenes complex are integrated into a synthesis of its tectonic evolution constraining the main tectonothermal events important aspects of this synthesis are 1 the interpretation of cambro ordovician magmatism and earliest metamorphic event as the result of drifting of a peri gondwanan terrane 2 the subsequent shortening and crustal thickening of the terrane related to its subduction and accretion to laurussia 3 a younger cycle of shortening and extension resulting from convergence between lau russia and gondwana and 4 the emplacement of this exotic terrane as the upper allochthon together with underlying ophiolitic and basal allochthons during the laurussia gondwana collision implications derived from the well established tectonothermal sequence are discussed in the context of paleozoic paleogeography and geodynamics the evolution of this part of the belt is related first to the closure of the tornquist ocean and later to that of the eastern branch of the rheic ocean furthermore the relative paleopo sitions of the upper allochthon and the iberian autochthon in northern gondwana are discussed 2007 geological society of america all rights reserved