the exposed base of a collapsing wedge the nestos shear zone rhodope metamorphic province greece 1 the nestos shear zone nsz in the rhodope metamorphic province is a major high strain zone between two metamorphic terranes microdiamond bearing ultrahigh pressure uhp rocks occur in the nsz which was therefore interpreted as a suture zone where subduction and exhumation of these rocks and terrain accretion occurred during the mesozoic our petrological study of samples from the lower part of the nsz together with monazite dating of a microdiamond bearing garnet schist structural observations already published results from the upper part and other published timing constraints results in a fundamentally different picture the nsz is the base of an eocene age southwestward thrust wedge which included not only the structurally higher parts of the rhodope metamorphic province but also the entire internal hellenides the uhp rocks for the peak pressure of which we derive an age of 200 ma by monazite dating are unrelated to the tectonic processes in the nsz and probably represent slivers of a higher tectonic unit captured by thrusting along the nsz pressure decrease in the footwall and regional extension and basin formation in the hanging wall during the activity of the nsz show that the overlying thrust wedge was collapsing in late eocene times we hypothesize that the transition from subduction to continental collision may start with a pronounced accretion event when the first detachment horizon forms in the middle crust of the downgoing plate such an event could trigger slab retreat an extensional collapse of the internal wedge and subsequent magmatism

strike slip duplexes abstract strike slip fault systems often contain zones of steep imbricate faults geometrically similar to imbricate fans and duplexes in dip slip thrust and normal fault systems they are evident in map view rather than in vertical sections examples of duplexes are cited from both active and ancient systems and from theoretical and physical models duplexes may form at bends on strike slip faults by a process kinematically analogous to the sequential imbrication of ramps on dip slip faults however some may form and many may initiate as non sequential riedel fractures at fault offsets or on straight fault segments this process is more marked than in dip slip systems where primary anisotropy such as bedding exerts more control on fault geometry strike slip duplexes may be shunted along the fault system parallel to the regional slip vector however duplexes or individual horses will usually also move up or down perpendicular to the slip vector because of the unconstrained upper surface to the fault system these factors mean that no section through a strike slip system should be expected to area balance the faults of strike slip duplexes and imbricate fans may root in kinematically necessary low dip faults or may converge downwards and appear in vertical sections as flower structures

syn metamorphic nappe complex in the rhodope massif structure and kinematics mylonitic gneisses of the bulgarian and greek rhodope were deformed under medium pressure type metamorphism the kinematic information contained in these gneisses shows that shear deformation occurred during development of a nappe complex lithologies and metamorphic histories allow a lower footwall and an upper hanging wall terrane to be distinguished that define a crustal scale duplex as oceanic crust is involved collision between two continental units with subsequent crustal thickening is inferred the blocks would be moesia to the north and the lower rhodope promontory to the south which collided in the mesozoic to early cenozoic the nappe complex is characterized by south to southwestward foreland directed piling up and is associated with both coeval and subsequent extension the late extension is associated with the establishment of a high temperature low pressure metamorphic gradient and plutonism that predates but makes a transition to the lithospheric extension of the aegean arc

tectonometamorphic evolution of the rhodope orogen 1 this study combines new data on tectonostratigraphy macrostructures and microstructures petrology and geochronology to propose a comprehensive model for the tectonometamorphic evolution of the rhodope orogen from the jurassic to the early paleogene rocks from two study areas in the central and eastern greek rhodope represent a continental suture zone rhodope suture zone with the included material most likely forming an extensional allochthon south of the european continent during permo triassic times that was subsequently subducted beneath europe in the early jurassic 180 ma on the basis of comparable metamorphic ages and coherent structures but differences in metamorphic conditions and lithologies the rocks of the rhodope suture zone are subdivided into an upper and a lower part the prograde history is linked with subduction related structures in the lower part uniaxial stretching deformation stage d1 in metapelites the earliest stage of metamorphism recorded at circa 180 ma occurred at least under ultrahigh pressure metamorphic conditions the rocks of the upper part experienced isothermal decompression with partial anatexis exhumation paths of both parts differ in temperature because of the relative tectonic position within the exhuming wedge exhumation was forced by the nestos shear zone that controlled the early phase of normal displacement by sw shearing at the base lower part and ne shearing on top upper part from the late jurassic to the late cretaceous deformation stage d2 an intervening stage of mineral recrystallization and thermal reequilibration in the upper part was followed by a common exhumation history of both parts at pressures lower than about 12 kbar 35 40 km depth during this stage exhumation was controlled by southwest directed shearing and folding deformation stage d3 slab retreat to the south led to subsequent extension deformation stage d4 and final exhumation coeval with the formation of basement domes thus making the rhodope a classic core complex juxtaposed with former structurally higher units

exhumation of high pressure rocks driven by slab rollback rocks metamorphosed under high pressure hp and ultra high pressure uhp conditions in subduction zones come back to the surface relatively soon after their burial and at rates comparable to plate boundary velocities in the mediterranean realm their occurrence in several belts related to a single subduction event shows that the burial exhumation cycle is a recurrent transient process using the calabria apennine and aegean belts as examples we show that the exhumation of hp rocks is associated in time and space with the subduction of small continental lithosphere blocks that triggers slab rollback creating the necessary space for the exhumation of the buoyant continental crust that was deeply buried just before the buoyancy force of the subducted crust increases until this crust detaches from the downgoing slab it then exhumes at a rate that depends directly on the velocity of trench retreat to become part of the overriding plate heated from below by the asthenosphere that flows into the opening mantle wedge the exhumed crust weakens and undergoes core complex type extension responsible for a second stage of exhumation at a lower rate the full sequence of events that characterizes this model crust mantle delamination slab rollback and trench retreat hp rock exhumation asthenosphere heating and core complex formation arises entirely from the initial condition imposed by the subduction of a small continental block no specific condition is required regarding the rheology and erosion rate of hp rocks the burial exhumation cycle is transient and can recur every time a small continental block is subducted

nappe stacking resulting from subduction of oceanic and continental lithosphere below greece we quantitatively investigate the relation between nappe stacking and subduction in the aegean region if nappe stacking is the result of the decoupling of upper crustal parts 5 10 km thick from subducting lithosphere then the amount of convergence estimated from balancing the nappe stack provides a lower limit to the amount of convergence accommodated by subduction the balanced nappe stack combined with the estimated amount of completely subducted lithosphere indicates 700 km of jurassic and 2400 km of post jurassic convergence from seismic tomographic images of the underlying mantle we estimate 2100 2500 km of post jurassic convergence we conclude that 1 the imaged slab represents the subducted lithosphere that originally underlay the nappes 2 since the early cretaceous subduction in the aegean has occurred in one single subduction zone and 3 the composition of the original basement of the nappes indicates that at least 900 km of sub upper crust continental lithosphere subducted in the aegean

structural and geochronological evidence for paleogene thrusting in the western rhodopes sw bulgaria elements for a new tectonic model of the rhodope metamorphic province 1 the rhodope metamorphic province in the area around the mesta graben sw bulgaria exposes a structurally lower complex the pangaion pirin complex of variscan continental crust and its cover mostly orthogneiss and marble and a higher complex the rhodope terrane of mixed oceanic and continental origin with metamorphosed jurassic arc magmatites the boundary between the two is the top to the southwest nestos shear zone the regional top to the southwest shearing of the two basement complexes is related to the emplacement of the rhodope terrane over the pangaion pirin complex along this shear zone syntectonic and posttectonic alpine intrusions within the basement can provide age limits for the thrusting zircons from the posttectonic teshovo south pirin granitoid pluton in the pangaion pirin complex yielded crystallization ages of 32 0 2 ma la sf icp ms u pb method zircons from two syntectonic granite plutons in the rhodope terrane dolno dryanovo and spanchevo have circa 143 to 145 ma old inherited magmatic cores and circa 55 to 56 ma old magmatic rims these ages especially the presence of the upper jurassic lower cretaceous cores in the plutons from the rhodope terrane and the structural relations indicate that the southwestward thrusting of the rhodope terrane over the pangaion pirin complex took place in the paleogene a model is proposed in which the pangaion pirin complex represents the margin of apulia and the structure of the rhodopes is explained by a switch of subduction polarity from sw dipping in the jurassic and early cretaceous to ne dipping in the late cretaceous and paleogene

structure and strain variation at mid crustal levels in a transpressional orogen a review of kaoko belt structure and the character of west gondwana amalgamation and dispersal abstract the neoproterozoic cambrian kaoko belt is an orogen scale 800 180 km transpressional system important in the amalgamation of west gondwana mid crustal transpression at amphibolite to granulite facies conditions is dominated by two major 400 km exposed strike slip shear zones bounding a 20 40 km wide high grade orogen core to the east a deeply buried nappe dominated escape zone has inverted metamorphic sequence and verges outwards onto a platformal foreland to the west an arc like neoproterozoic coastal terrane was amalgamated and variably reworked during transpression the major purros and three palms mylonite zones have calculated shear displacements on the order of 120 180 km these shear zones are moderately to steeply dipping mylonite zones of 1 5 km width are arcuate and curvilinear in map view and show along strike variation in slip kinematics also highly curved in vertical section the shear zones define a flower to half flower geometry for the orogen core an oblique network of mylonitic shear zones akin to riedel shears links the major shear zones and defines regional scale shear lozenges internally deformed by tight upright folding and shear fabrics these shear zones create domains in the orogen core with varying dominance of pure shear in shear lozenges and simple shear in shear zones however absence of dip slip domains and the smoothly continuous traces of sub horizontal to shallow and acute oblique stretching lineations across all parts of the belt preclude marked kinematic partitioning and the internal part of the belt resembles large scale triclinic shear clast aspect ratios boudin train extension sheath fold aspect geometry degree of rotation of planes producing flanking folds composite s c foliations pressure fringes on pyrite and garnet porphyroclasts provide a semi quantitative measure of strain intensity average strain ratios are x z 40 1 for the major shear zones x z 12 1 for the orogen core x z 8 1 for the escape zone and x z 3 1 for the coastal terrane a more continuous pattern of strain intensity across the whole belt is mapped using a qualitative foliation intensity index foliation traces have a sigmoidal pattern in the orogen core swinging from sub parallel to the boundary shear zones to higher acute angles in the internal parts deformation character also varies from upright open folding in amphibolite facies domains in the north upright tight chevron folding in a low grade central domain to a high grade domain of tight to isoclinal inter folded basement and cover with inclination decreasing towards the south the kaoko belt is a well exposed sector of an extensive 3000 km long broad 400 km arcuate orogenic system adamastor orogen that amalgamated west gondwana bringing the south american sao francisco and rio de la plata cratons and african kalahari and congo cratons components together though a complex system most sectors involved oblique collision and accretion of magmatic arcs of 660 610 ma age followed by peak metamorphism and main phase transpressional orogenesis between 585 and 560 ma with shear zones remaining active until 530 ma this e w amalgamation immediately pre dates the final n s amalgamation of gondwana along the kuunga orogen between 535 and 510 ma the large scale adamastor orogen consisting of kaoko dom feliciano ribeira aracuai and west congo mobile belts also shows broadly similar and symmetric structural architecture throughout the high grade thermally softened core partitioned intense wrench dominated strains and networks of transcurrent shear zones that dip inwards with listric form either side of the internal zone containing amalgamated arcs and high grade core are nappe fold and thrust belts that rework attenuated passive margin basement and adamastor ocean sediments and structures verge outward at moderate to high angles onto both foreland margins the kaoko belt well illustrates the highly partitioned nature of transpressional systems in general and patterns in common throughout the greater adamastor orogen such as metamorphic zonation and heterogeneous distribution of deformation style flow regime and highly variable degrees of reworking strain and recrystallization this highly partitioned and steep structural grain localized lithospheric extension and rifting 415 ma later during breakup and dispersal of gondwana

assessing the control exerted by soil mineralogy in the fixation of potentially harmful elements in the urban soils of lisbon portugal the main purposes of this study are the textural chemical and mineralogical characterization of the urban soils of lisbon and the identification of probable relations between the several soil properties the results are used to infer which soil properties control the superficial dispersion of potential harmful elements to human health soil sampling was carried out in 51 selected sites all through the city under the criterion that such sites should be spaces usually frequented by children the concentrations of 42 elements in the 2 mm soil size fraction were determined at a commercial laboratory in canada actlabs ltd by icp ms icp oes after an acid digestion with aqua regia the soil mineralogy was determined by x ray diffraction in the 2 and 62 m size fractions the results indicate that the urban soils have mainly a sandy texture and a main mineralogical assemblage of quartz k feldspar plagioclase and calcite in terms of clay minerals smectite illite and kaolinite are the main clays in the soil smectite and illite show a dichotomy in their distribution with the smectites prevailing in the soils of the volcanic complex of lisbon which are classified as being residual and illite prevailing in the remaining soils which are considered mainly as man made soils smectite seems to exert an important role in the fixation of ni and cr the results of the geochemical study show that ni and cr have concentrations above the soil guideline value established to the uk and pose a probable risk to human health

kinematic significance of l tectonites in the footwall of a major terrane bounding thrust fault klamath mountains california usa abstract detailed geologic mapping cross section reconstructions strain analyses and kinematic analyses enable the reconstruction of a one kilometer wide domain of l tectonites in the east west striking subhorizontal to gently south dipping pigeon point high strain zone pphsz associated with a major thrust fault separating oceanic and arc affinity terranes in the klamath mountains california l tectonites are associated with 1 a convex upward warp of the upper high strain zone boundary 2 a transition from mafic metavolcaniclastic rocks to micaceous quartzites 3 folds subparallel with mineral lineations 4 emplacement of synkinematic ultramafic mafic intrusive bodies and 5 a local temperature increase from greenschist to amphibolite facies conditions pure shear dominated deformation accommodated zone normal shortening and transport parallel elongation coupled with subordinate top to the west directed thrust style simple shear l tectonite formation was controlled by the shape of the high strain zone boundary driving lateral flow into the apex of the lens shaped zone in response to a favorable kinematic geometry and bulk strain in the constrictional field localized magmatic heating best explains the shape of the high strain zone boundary but l tectonites are not partitioned into a single rheological domain during terrane amalgamation strain path partitioning occurred with localized top to the west directed simple shear partitioned into a structurally overlying thrust zone and pure shear dominated subvertical shortening and transport parallel elongation partitioned into the pphsz

implications of shear sense criteria for the tectonic evolution of the central rhodope massif southern bulgaria a systematic record of sense of shear criteria associated with peak conditions of amphibolite facies metamorphism from the central rhodope massif bulgaria gives evidence for superposition of two distinct terranes the lower terrane is characterized by south vergent flat lying thrusting that involved eclogites the upper terrane is characterized by east vergent flat lying shearing possibly associated with crustal extension we suggest that both regional metamorphism and deformation may be cretaceous in age there was erosion prior to emplacement of several crystalline sheets at shallow depths during the early cenozoic this was followed by oligocene extension and rhyolitic volcanism the rhodope massif can no longer be regarded as a stable paleozoic or older microcontinent

metamorphozed hercynian granitoids in the alpine structures of the central rhodope bulgaria geotectonic position and geochemistry abstract orthogneisses of late hercynian protolith age crop out in the central rhodope high grade metamorphic complex which is part of the alpine orogen in south eastern europe they compose a tectonic unit bordered by late alpine extensional shear zones these rocks reflect eocene amphibolite facies migmatization

geochronological and structural constraints on the cretaceous thermotectonic evolution of the kraishte zone western bulgaria 1 in the kraishte region near the junction of the balkanides and dinarides late early cretaceous compression led to the thrusting of the morava unit over the struma unit structural investigations combined with zircon fission track and 40ar 39ar analyses have been used to reconstruct the geological history of the area and to clarify the original tectonic position of the main units before cenozoic extension the results show that early cretaceous lower amphibolite facies metamorphism and deformation in the osogovo lisets metamorphic complex were related to top to the ne directed nappe stacking whereas the deeper parts of the allochthonous morava unit experienced low grade metamorphic overprint at temperatures 260 c the structurally intermediate struma diorites and their mesozoic cover experienced temperatures between 170 c and 300 c thrusting of the morava onto the struma unit started probably in valanginian times 140 136 ma soon after the cessation of preorogenic to synorogenic turbidite sedimentation on struma the metamorphic peak was reached before 112 ma subsequent extension related cooling of both units was probably accompanied by the formation of low angle normal faults

plate tectonic evolution of the southern margin of eurasia in the mesozoic and cenozoic abstract thirteen time interval maps were constructed which depict the triassic to neogene plate tectonic configuration paleogeography and general lithofacies of the southern margin of eurasia the aim of this paper is to provide an outline of the geodynamic evolution and position of the major tectonic elements of the area within a global framework the hercynian orogeny was completed by the collision of gondwana and laurussia whereas the tethys ocean formed the embayment between the eurasian and gondwanian branches of pangea during late triassic early jurassic times several microplates were sutured to the eurasian margin closing the paleotethys ocean a jurassic cretaceous north dipping subduction boundary was developed along this new continental margin south of the pontides transcaucasus and iranian plates the subduction zone trench pulling effect caused rifting creating the back arc basin of the greater caucasus proto south caspian sea which achieved its maximum width during the late cretaceous in the western tethys separation of eurasia from gondwana resulted in the formation of the ligurian penninic pieniny magura ocean alpine tethys as an extension of middle atlantic system and a part of the pangean breakup tectonic system during late jurassic early cretaceous times the outer carpathian rift developed the opening of the western black sea occurred by rifting and drifting of the western central pontides away from the moesian and scythian platforms of eurasia during the early cretaceous cenomanian the latest cretaceous paleogene was the time of the closure of the ligurian pieniny ocean adria alcapa terranes continued their northward movement during eocene early miocene times their oblique collision with the north european plate led to the development of the accretionary wedge of the outer carpathians and its foreland basin the formation of the west carpathian thrusts was completed by the miocene the thrust front was still propagating eastwards in the eastern carpathians during the late cretaceous the lesser caucasus sanandaj sirjan and makran plates were sutured to the iranian afghanistan plates in the caucasus caspian sea area a north dipping subduction zone jumped during paleogene to the scythian turan platform the shatski terrane moved northward closing the greater caucasus basin and opening the eastern black sea the south caspian underwent reorganization during oligocene neogene times the southwestern part of the south caspian basin was reopened while the northwestern part was gradually reduced in size the collision of india and the lut plate with eurasia caused the deformation of central asia and created a system of nw se wrench faults the remnants of jurassic cretaceous back arc systems oceanic and attenuated crust as well as tertiary oceanic and attenuated crust were locked between adjacent continental plates and orogenic systems

characterisation of igneous terranes by zircon dating implications for uhp occurrences and suture identification in the central rhodope northern greece the occurrence of ultra high pressure uhp and high pressure hp relicts associated with oceanic material suggests the presence of a suture zone within the rhodope massif characterisation of the accreted igneous terranes and their relationship with the uhp eclogite occurrences provide new constraints on the location of this suture single zircon evaporation and sensitive high resolution ion microprobe dating of orthogneiss protoliths define two groups of intrusion ages permo carboniferous and late jurassic early cretaceous structurally the late jurassic gneissic complex overthrust a unit with permo carboniferous orthogneisses a melange zone marked by mylonites eclogites amphibolites and uhp micaschists separates these two units we interpret these observations in terms of two distinct igneous terranes the thracia permo carboniferous and rhodope late jurassic terranes separated by the nestos suture and assembled during the closure of an oceanic basin of the tethys geochemically the late jurassic rocks are akin to subduction magmatism possibly the same subduction that caused the uhp metamorphism of metasediments within the melange zone observed uhp hp relicts are restricted to the tectonic contact zone suggesting that a single subduction collison event can explain the occurrences of uhp relicts and eclogites in the central rhodope and that subducted rocks are exhumed only within the nestos suture

time constraints for low angle shear zones in the central rhodopes bulgaria and their significance for the exhumation of high pressure rocks in the central rhodopes of southern bulgaria an eclogite bearing rock sheet belonging to the middle allochthon starcevo unit is over and underlain by eclogite free amphibolite facies rock units along low angle shear zones the borovica shear zone at the top and the starcevo ardino shear zone at the base the age of these shear zones is determined by u pb zircon dating of pre syn and posttectonic magmatic rocks mostly pegmatite veins using la sf icp ms zircons from pre to syntectonic pegmatites within the borovica shear zone yielded ages of ca 45 43 ma indicating that the shear zone was active at that time and zircons from a pretectonic pegmatite and a posttectonic granitoid body within the starcevo ardino shear zone yielded ages of ca 45 and ca 36 ma respectively giving a time frame for the activity of that shear zone which probably rather postdated the activity of the borovica shear zone by combining the ages with the kinematics of the shear zones and the metamorphic history of the rock units the following scenario is sketched soon after the starcevo unit reached peak pressure eclogite facies it was exhumed to a mid crustal level by top to the north west extensional unroofing along the borovica shear zone in a kinematic framework of orogen parallel extension beginning at ca 40 ma the partly exhumed starcevo unit was underthrust from the south west by continental crust of the foreland apulia forming the lower allochthon of the rhodopes along the starcevo ardino shear zone these results underline the significance of orogen parallel extension for the exhumation of high pressure rocks with respect to regional geology of the hellenides and the aegean it is found that the tectonic architecture of the rhodopes is essentially of tertiary age cretaceous syn metamorphic shear zones do exist but are largely restricted to higher levels of the nappe stack upper allochthon the rhodopes do not represent an older essentially mesozoic core of the hellenides but are formed by the internal higher metamorphic portions of the same major nappe systems as occur in the hellenides

the origin of ridge in groove slickenside striae and associated steps in an s c mylonite abstract a three dimensional study of an s c mylonite reveals that the s surfaces anastomose around porphyro clasts and c surfaces are not truly planar but curvi planar with the linear generator parallel to the movement direction it is suggested that it may be common for shear surfaces at all scales to take this form in the material studied surfaces exposed by parting primarily along c surfaces which are a product of ductile deformation and are penetrative have all the characteristics of classic slickensides on the slickensides striae of the ridge in groove type and steps of both congruous and incongruous types are developed the ridge in groove shape of the striae is directly related to the curvi planar shape of the c surfaces incongruous steps are smooth they are the result of parting along s surfaces congruous steps are rough first order congruous steps are formed by fracturing between individual c surfaces whereas second order congruous steps form by breaking off the tips of the dihedra between s and c surfaces thus the smoothness roughness technique can be used to determine the sense of shear in strongly deformed rocks where the angle between s and c surfaces is too small to be recognized in the field this may prove to be a useful shear sense indicator

the tectonics of the strandja massif late variscan and mid mesozoic deformation and metamorphism in the northern aegean the strandja massif is a mid mesozoic orogenic belt in the balkans build on a late variscan basement of gneisses migmatites and granites new single zircon evaporation ages from the gneisses and granites indicate that the high grade metamorphism and plutonism is early permian in age 271 ma the late variscan basement was unconformably overlain by a continental to shallow marine sequence of early triassic mid jurassic age during the late jurassic early cretaceous oxfordian barremian the lower mesozoic cover and the basement were penetratively deformed and regionally metamorphosed in greenschist facies possibly due to a continental collision an rb sr biotite whole rock age from a metagranite dates the regional metamorphism as late jurassic 155 ma deformation involved north vergent thrust imbrication of the basement and the emplacement of allochthonous deep marine triassic series over the jurassic metasediments the metamorphic rocks of the strandja massif are unconformably overlain by the cenomanian shallow marine sandstones during the senonian the northern half of the strandja massif formed a basement to an intra arc basin and to a magmatic arc generated above the northward subducting tethyan oceanic lithosphere the srednogorie arc closed during the early tertiary through renewed northward thrusting of the strandja massif

stable carbon isotopes from tornetrask northern sweden provide a millennial length reconstruction of summer sunshine and its relationship to arctic circulation this paper presents results from the first 1100 years of a long stable carbon isotope chronology currently in development from scots pine pinus sylvestris l trees growing in the tornetrask region of northern sweden the isotope record currently comprises a total of 74 trees with a mean annual replication of 12 thereby enabling it to be compared directly with other tree ring based palaeoclimate reconstructions from this region in developing the reconstruction several key topics in isotope dendroclimatology chronology construction replication co2 adjustment and age trends were addressed the resulting carbon isotope series is calibrated against instrumental data from the closest meteorological station at abisko ad1913 2008 to provide a record of june august sunshine for northern fennoscandia this parameter is closely linked to the direct control of assimilation rate photosynthetically active radiation par and the indirect measures mean july august temperature and percent cloud cover the coupled response of summer sunshine and temperature in this region permits a multiparameter comparison with a local reconstruction of past temperature variability based upon tree growth proxies to explore the stability of this coupling through time several periods are identified where the temperature x ray density and sunshine stable carbon isotope ratio records diverge the most significant and sustained of these occur between c ad1200 1380 and c ad1550 1780 providing evidence for a cool sunny two phase little ice age whilst summer sunshine reconstructed for the 20th century is significantly different from the mean of the last 1100 years p 0 01 so it is the 17th 18th and to a lesser extent the 13th centuries rather than the early medival period that appear anomalous when viewed within the context of the last 1100 years the observed departures between temperature and sunshine are interpreted as indicating a change in large scale circulation associated with a southward migration of the polar front such a change affecting the northern annular mode arctic oscillation would result in more stable anticyclonic conditions cool bright summers over northern fennoscandia thus providing a testable mechanism for the development of a multi phase time transgressive little ice age across europe

relations between the emplacement and fabric forming conditions of the kapitan dimitrievo pluton and the maritsa shear zone central bulgaria magnetic and visible fabrics analysis the kapitan dimitrievo pluton was emplaced within the 15 km wide maritsa shear zone during the late cretaceous it has well known u pb zircon age 78 54 0 13 ma and appears as a late syntectonic intrusion that marked the last ductile deformation in the maritsa shear zone magnetite is believed to be the main carrier of the magnetic fabric in this pluton and crystallized mainly late after the main rock forming minerals two fabrics are recorded a visible syn magmatic fabric due to magma flow and magnetic late magmatic fabric related to regional stresses although different both are mainly related to the shearing along this shear zone these results constrain in age the dextral strike slip controlled emplacement and evolution of the late cretaceous plutons from central bulgaria

importance of differentiating ductile slickenside striations from stretching lineations and variation of shear direction across a high strain zone shear direction is an important parameter in the kinematic interpretation of high strain zones recent developments in the study of high strain zones show that there is no simple relationship between the orientation of stretching lineations and the shear direction and it is difficult to use the former to determine the latter in contrast striations on c surfaces a product of ductile deformation form parallel to the shear direction it is therefore important for the kinematic interpretation of high strain zones to differentiate such striations from stretching lineations ductile striations are much more common in natural high strain zones than reported in the literature we discuss how to differentiate the two types of lineations and describe a natural high strain zone example from the superior craton of canada the striation data show that the shear direction of the high strain zone varies from subhorizontal to moderately plunging across the strike of the zone we conclude that well developed ridgein groove type striations are a reliable indicator of the shear direction we also discuss situations where the orientation of stretching lineations can potentially be used as an indicator of shear direction 2007 elsevier ltd all rights reserved

3 geochronology and geodynamics of late cretaceous magmatism and cu au mineralization in the panagyurishte region of the apuseni banat timok srednogorie belt bulgaria abstract the apuseni banat timok srednogorie abts belt europe s most extensive belt of calc alkaline magmatism and cu au mineralization is related to the subduction of the tethys ocean beneath the european continental margin during the late cretaceous phase of the alpine himalayan orogeny economic deposits are restricted to certain segments along the belt and all major porphyry style and high sulphidation ore deposits in bulgaria are aligned on the panagyurishte corridor a narrow zone obliquely crossing the abts belt this paper reviews the geology geochemistry and geochronology of igneous and hydrothermal events along this corridor in a profile extending from the european continental basement in the north to the accretionary complex of the rhodopes in the south extensive u pb dating of zircons from subvolcanic intrusions and major plutons supplemented by published age data for magmatic rocks and hydrothermal ore deposits obtained by other methods reveals a general younging of magmatism from ca 92 ma in the north elatsite to ca 78 ma in the south capitan dimitrievo cu au deposits are restricted to the northern and central parts of the profile ranging in age from 92 to 86 ma while the southernmost part exposes more deeply eroded mid crustal plutons devoid of economic mineralization the age progression correlates with a north to south geochemical trend of decreasing crustal input into mantle derived magmas magmatism and ore formation in individual magmatic hydrothermal complexes along the profile is much shorter lived for example subvolcanic intrusions and porphyry cu au mineralization at the elatsite deposit and andesitic volcanism and high sulphidation au as cu mineralization at chelopech all occurred within a time span of about 1 million years the age progression of calc alkaline magmatism within the panagyurishte region bulgaria from north to south is explained as a consequence of slab retreat during oblique subduction this led to transtensional block faulting and subsidence and thus to the preservation of near surface magmatic hydrothermal products including economic cu au deposits accretion of continental fragments in the rhodopes south of the abts belt led to greater uplift of the youngest late cretaceous intrusions this removed any ore deposits that might have been formed in this area

structural significance of l tectonites in the eastern central laramie mountains wyoming abstract the formation of l tectonites is little understood and scarcely studied however it is probably an important part of plastic deformation in the crust to improve our understanding of this strain phenomenon i present a detailed case study of a kilometer wide domain of l tectonites developed in and around the 2 05 ga boy scout camp granodiorite bscg in the laramie mountains wyoming detailed mapping and structural analyses allow for the reconstruction of the structural setting of this domain of apparent constrictional strain elongation lineations plunge moderately to the south southwest and lie parallel with both the local fold hinge lines and regional fold axes whereas poles to foliation generally cluster in the northwest quadrant roughly defining fold axial surfaces map scale folds are west northwest vergent but at the outcrop and thin section scales there is no evidence for a significant component of simple shear reconstruction of the orientation of contacts in and around the bscg i

the maritsa strike slip shear zone between kostenets and krichim towns south bulgaria structural petrographic and isotope geochronology study abstract the present study describes the characteristics of the maritsa shear zone msz a major tectonic element in the balkanides in south central bulgaria metamorphic rocks of four lithotectonic units madan chepinska asenitsa and thrace units crop out in the study area strike slip ductile deformation in msz affects the thrace lithotectonic unit tlu for up to 15 km the stratigraphy of this unit is divided in two parvenets succession and variegated succession u pb zircon dating reveals late jurassic protolith age for metagranitoids and metagabbros of the variegated succession for its metasedimentary part triassic to upper jurassic age is suggested based on the strontium isotope signature of the marbles the parvenets succession affiliates to the variscan metamorphic basement of europe the metamorphic evolution of the zone is subdivided into synmetamorphic strike slip deformations and annealing stages the ductile shearing occurred in greenschist to lower amphibolite facies between 130 ma discordant u pb ages and 82 78 ma late syntectonic granites this stage is connected with the oblique collision of the rhodope late jurassic arc with the european platform with the docking of the arc and the triggering of the strike slip movements msz represents an orogen scale border between the rhodope south vergent thrust complex and the north vergent deformations in the srednogorie and sakar strandzha zones during the late cretaceous msz is the contact between the srednogorie magmatic arc part of the apuseni banat timok srednogorie belt and the rhodopean metamorphic core complexes nw se dextral faulting characterized the brittle tectonics along the zone strike slip faults of the southern border of the tlu are transferred into reverse faults along which the tlu overthrusted oligocene sediments msz is an orogen scale transpressional shear zone and an important border in the structure of the balkanides this multidisciplinary research emphasizes its role as a major tectonic element by presenting new structural petrographic and isotope geochronology data