high frequency cycles within pleistocene forced regressive conglomerate wedges bradanic area southern italy filling collapse scars middle pleistocene sedimentation in the bradanic area foreland basin of the southern apennines took place in a setting in which tectonic tilting created anomalous shelf gradients and where slope failures repeatedly occurred at the front of quickly prograding sedimentary wedges a coarse grained wave dominated coastal deltaic complex consisting of two downstepping forced regressive wedges prograded during the falling stage of a middle pleistocene glacio eustatic fluctuation p lacunosa zone conglomerate clinoforms show a dramatic increase in relief and steepness as a result of the infill of collapse scars compaction of prodelta mudstones due to the load of the scar filling conglomerates resulted in a slight deformation of the fills into broad synformal structures with gentle anticlinal closures at their distal ends accommodation space was created resulting in splitting of the prograding bodies into high frequency cycles which are thought to reflect the interaction of localized compactional subsidence with autocyclic shifting of river mouths and or climatically induced variations in sediment supply available chronologic constraints suggest average durations of small scale cycles on time scales shorter than those of milankovitch orbital frequencies this case history highlights the importance of some factors which are often neglected in sequence stratigraphic models e g physiography of the sea floor and localized sediment loading on one hand the bulk of falling stage wedges can be preserved as they prograde into intraplatform depressions represented by collapse scars on the other significant accommodation space is created by compactional subsidence leading to the splitting of a simple progradational unit into multiple small scale cycles

upper mantle flow in eastern europe we present and discuss estimates of shear wave splitting in the upper mantle of eastern europe based on sks techniques estimates of the direction of polarization of the fast split wave and the delay of the slow wave t are obtained at seven stations uzh kov and lvv within and near the carpathians sim sev and yal in the crimean peninsula and kiev in the russian plate fast directions at all stations are around 130 close to the values previously found in central europe in the carpathians similar values of t are observed within the pannonian depression where the subcrustal lithosphere if present is very thin and in the foredeep with a thick subcrustal lithosphere this similarity suggests that the observed anisotropy is not inherited from earlier orogenies and preserved in the lithosphere in the crimea the fast direction of anisotropy in the mantle is perpendicular to the strike of the crimean mountains of late jurassic cretaceous age contrary to the expected alignment of the fast direction with the strike of a collisional belt in general the data are consistent with a present day or recent large scale mantle flow in central and eastern europe parallel to the alpine belt

evidence for ancient lithospheric deformation in the east european craton based on mantle seismic anisotropy and crustal magnetics abstract we present new shear wave splitting measurements performed at 16 stations on the east european craton and discuss their implications in terms of upper mantle anisotropy for this geophysically poorly known region previous investigations of mantle anisotropy in central europe have shown fast directions aligning smoothly with the craton s margin and various suggestions have been proposed to explain their origin such as asthenospheric flow or lithospheric frozen in deformation here we aim at investigating the continuation of this shear wave splitting pattern further to the east into the east european craton for the craton the interpretation appears to be less ambiguous than for central europe since several arguments support lithospheric anisotropy in this region 1 the large scale coherence within either of the four constituting blocks and the significant variations between the blocks on a small scale 2 the weak correlation with absolute plate motion vectors and 3 the good correlation between anisotropy and crustal features for which we use magnetic field alignments as a proxy rather good correlation of these magnetic features with seismic fast orientations strongly supports the idea of vertically coherent deformation throughout upper mantle and crust the observed splitting orientations thus reflect the last tectonic events of each block frozen in into the lithosphere for hundreds of millions of years

models of seismic anisotropy in the deep continental lithosphere seismological observations sks wave polarizations systematic p residual variations azimuthal dependence of pn and surface wave velocities or a dispersion of surface waves are not consistent with isotropic if laterally heterogeneous upper mantle structure therefore an anisotropy should be considered as an a priori aspect of future large scale studies of mantle structure most studies of anisotropy however have assumed horizontal or vertical axes of symmetry but such orientations cannot explain bipolar patterns of spatial variations of p residuals which we have observed at many seismological stations on the basis of the petrophysical properties of real upper mantle rocks we consider anisotropy formed either by hexagonal or by orthorhombic aggregates composed of olivine orthopyroxene and clinopyroxene rotations of the aggregates about vertical and horizontal axes allow us to find the three dimensional orientations of symmetry axes that fit combinations of both p and s seismological observations in central europe and in western north america the orientations with plunging symmetry axes velocity extremes seem to be consistent across large spatially uniform tectonic units and change abruptly at important suture zones

sks splitting observed at romanian broad band seismic network abstract shear wave splitting results are presented for the broad band stations of the romanian seismic network for stations buc1 and crar located in moesian platform ias in east european platform tirr and cvd in central dobrudja black sea microplate tim and drgr in dacia tisza plate including apuseni mts burar bzs and gzr in or very close to the carpathian arc the fast directions are around 135 the mean delay values t of the slow wave are slightly greater for the stations placed in platform areas t 1 5 s than for the stations situated in the proximity of carpathians t 1 2 s for the mlr station located in the south western part of vrancea area at the carpathian bend the fast direction is 48 similar to voir station located in southern carpathians 70 km west of mlr at vri and plor located in the north eastern part of vrancea the fast axis is oriented approximately on north south direction with a possible dependence of the splitting parameters with back azimuth at least for some stations the splitting results are not consistent with vertical coherent lithospheric anisotropy

seismic anisotropy and mantle creep in young orogens summary seismic anisotropy provides evidence for the physical state and tectonic evolution of the lithosphere we discuss the origin of anisotropy at various depths and relate it to tectonic stress geotherms and rheology the anisotropy of the uppermost mantle is controlled by the orthorhombic mineral olivine and may result from ductile deformation dynamic recrystallization or annealing anisotropy beneath young orogens has been measured for the seismic phase pn that propagates in the uppermost mantle this anisotropy is interpreted as being caused by deformation during the most recent thermotectonic event and thus provides information on the process of mountain building whereas tectonic stress and many structural features in the upper crust are usually orientated perpendicular to the structural axis of mountain belts pn anisotropy is aligned parallel to the structural axis we interpret this to indicate mountainparallel ductile i e creeping deformation in the uppermost mantle that is a consequence of mountain perpendicular compressive stresses the preferred orientation of the fast axes of some anisotropic minerals such as olivine is known to be in the creep direction a consequence of the anisotropy of strength and viscosity of orientated minerals in order to explain the anisotropy of the mantle beneath young orogens we extend the concept of crustal escape or extrusion tectonics to the uppermost mantle we present rheological model calculations to support this hypothesis mountain perpendicular horizontal stress determined in the upper crust and mountain parallel seismic anisotropy in the uppermost mantle require a zone of ductile decoupling in the middle or lower crust of young mountain belts examples for stress and mountain parallel pn anisotropy are given for tibet the alpine chains and young mountain ranges in the americas finally we suggest a simple model for initiating mountain parallel creep

sequence stratigraphy of the upper oligocene lower miocene of eastern jylland denmark role of structural relief and variable sediment supply in controlling sequence development the upper oligocene lower miocene succession in eastern jylland can be subdivided into three sequences a c from older to younger deposited on and around the ringkobing fyn high the development of the sequences reflects a complex interaction between eustatic sea level changes physiography and variable sediment supply superimposed on this frequent storms promoted longshore sediment transport and the development of spit systems adjacent to structural highs as a consequence sequence boundaries and flooding surfaces are not always expressed as portrayed in conventional sequence models sequence boundaries or flooding surfaces may only be marked by subtle changes in depositional environment that can only be revealed by careful integration of sedimentological observations with palynological data the influence of the topography resulted in the development of brackish water basins that were sufficiently large to permit the deposition of hummocky cross stratified sands with muds these deposits are overlain by clean hummocky and swaley cross stratified sands that were deposited in a fully marine high energy environment this evolution from mud rich storm influenced sediments to sand dominated shoreface sediments resulted from a rise in sea level and was not the result of shoreface progradation and downstepping during a sea level fall in addition to the topographic control on sequence development sediment supply to the study area changed significantly during the deposition of the three sequences initially the basin was sediment starved favouring the formation of glaucony rich sediments the sediment input gradually increased and the influence of structural highs and lows became less significant with time consequently both sequence boundaries and flooding surfaces are characterized by more conventional features in the younger part of the succession where a basinward displacement of the shoreline resulted in thick lowstand delta deposits

progradational gravel beach sequences in a moderate to high energy microtidal marine environment the anatomy of progradational gravel beaches was analysed in two different tectonic settings the strongly subsiding messinian foreland basin of the eastern southern alps and the rising pleistocene marine terraces of the outer margin of the apenninic chain progradation took place near the mouths of fan delta or braid delta distributaries debouching in microtidal landlocked basins palaeo adriatic and palaeo ionian seas a wind wave climate comparable to that of the present day was characterized by periodic intense storm activity most of the beachface progradation is thought to have taken place during the post storm recovery and fair weather stages whereas the impact of storms is mostly recorded by the cutting of erosional surfaces on the beachface and by emplacement of poorly sorted and coarse grained gravels on the shoreface by storm intensified seaward trending flows and behind the highest berms by washover processes analysis of the sequences led to the identification of a number of typical divisions which are differently developed in the two settings compared here the characteristics of the apenninic sequences suggest a strongly variable wind wave climate with periodic changes from a relatively dissipative barred morphology during storms accompanied by strong longshore currents and rip development to a more reflective state typical of recovery and fair weather stages the southern alpine sequences on the other hand are characterized by poor evidence of barred morphology and of longshore currents and widespread effects of shear and gravity sorting in the lower beachface gravels these features indicate a comparatively more reflective average state due to location of beaches along the deeply embayed head of the palaeo adriatic and the very narrow directional width of the incoming wave spectrum which was almost shore normal most of the time in addition to well developed shape zonation of gravels the common presence of wave generated gravel megaripples in the southern alpine sequences indicates the greater influence of long period waves due to the greater available fetch distances in both settings the cyclicity is thought to be genetically related to minor changes of sea level

early holocene regressive spit platform and nearshore sedimentation on a glaciofluvial complex during the yoldia sea and the ancylus lake phases of the baltic basin sw finland abstract the depositional history of the virttaankangas plain a fan like enlargement of the large sakylanharju glaciofluvial ridge in sw finland is examined the sakylanharju ridge has been interpreted as having formed as an interlobate esker and the morphology of the virttaankangas plain as representing predominantly subaqueous glaciofluvial to glaciolacustrine deposition this investigation uses new sedimentologic outcrop data with extensive subsurface drilling gpr surveys seismic soundings and gravimetric measurement data provided by groundwater investigations to describe the stratigraphy morphology and depositional history of the plain in contrast to earlier interpretations the results emphasise the role of littoral processes in the origin of the virttaankangas plain the plain is interpreted as having originated during the development of a progradational sequence of spit platform and superimposed nearshore sediments deposited during the glacio isostatic forced regression of the yoldia sea and ancylus lake phases of the baltic basin 9900 9000 14 c bp documented depositional history supports an interval of retarded regression at the beginning of the ancylus lake phase i 9500 9200 14 c bp in the sakylanharju area

origin and consequences of cyclic ice rafting in the northeast atlantic ocean during the past 130 000 years deep sea sediment cores recovered from the northeast atlantic ocean were examined in order to elucidate the influence of the earth s orbital parameters on major ice rafting analyses of coarse grained ice rafted debris and planktonic foraminifers revealed a strong reaction to the precession signal since 130 000 yr b p dropstone layers have been deposited each half period of a precessional cycle 11 000 1000 yr ice rafting occurs during times of winter minimum summer maximum insolation and summer minimum winter maximum insolation in the first case high summer insolation forces meltwater discharge from the ice sheets into the polar seas which subsequently enhances formation of sea ice during the winter in the second case growth of continental ice enhances iceberg production which also leads to a salinity reduction of surface seawater both situations result in a southward penetration of polar water thus the marine record of dropstones documents ice rafting not only during weichselian stades but also during cold events within interstades the regularity of ice rafting yields a useful framework to calibrate and elucidate climatic changes not only in the region of the north atlantic ocean but also in remote areas such as the pacific ocean and the antarctic

the architectural variability of small scale cycles in shelf and ramp clastic systems the controlling factors many sedimentary successions are composed of metre to decametre scale cycles exhibiting various stratal architectures that depend on the complex interplay among several syndepositional controlling factors these controlling factors may produce extremely different stratal and facies architectures along relatively brief distances in the same basin but in contrast they also may form similar architectures in basins that experience a radically different tectonic setting the recognition of factors that controlled the architecture of small scale cycles therefore is very important to reconstruct the depositional history of sedimentary successions these factors include 1 the interplay between the rate of accommodation development and the rate of sediment supply a s 2 the amplitude and shape of the relative sea level curve 3 the position in the shoreface shelf system 4 the basin physiography 5 the shoreline trajectory 6 the climate driven environmental energy 7 the siliciclastic input vs carbonate production shoreface to shelf small scale cycles can be grouped into three main categories r cycles showing a dominant regressive interval t r cycles with transgressive and regressive intervals of similar thickness t cycles showing a dominant transgressive interval although some depositional settings may favour the deposition of a particular type of cycle these cycle motifs appear to be mainly controlled by the interaction of local and wider scale controlling factors for example t cycles may be present in both subsiding and uplifting settings depending on the interplay between the a s and the other factors cited above as a result r t r and t cycles may be recognized within the same depositional system these evidences suggest that care must be taken to apply general models that predict the stratal architecture of cycles mainly in function of the long term a s the correct prediction of the cycle architecture is important also for hydrocarbon researches as the thickness of potential reservoir deposits is the result of the interplay among factors discussed here

crystal growth during a single stage opening event and its implications for syntectonic veins abstract the crystallization of a fluid filled vein or cavity and interpretation of the microstructure in a deformed rock is an important problem for geologists dynamic crystallization experiments using ice and an aqueous solution have been used as an analogue system for single stage opening events and have shown that the presence or absence of a deviatoric stress is an important factor in the development of texture as a result of crystallization from a fluid the textures can vary from 1 coarse crystal aggregates involving static growth where there is no significant macroscopic deviatoric stress at the time of crystallization the free face growth model to 2 polycrystalline aggregates involving static growth which develop from a mixture of skeletal crystals and fluid in a stressed environment in the latter situation the crystals and fluid coexist until the macroscopic stress can be transmitted between impinging crystals and at this stage fast dynamic recrystallization and grain boundary migration occurs this recrystallization has been termed the contact growth model and the resulting metamorphic texture is compared with examples in natural quartz veins during a single stage vein opening uncomplicated by intragranular deformation either free face and or contact growth textures can develop from the fluid filled void depending upon the kinematic environment

coralline algal reef frameworks published and unpublished accounts of coralline algal reef frameworks are reviewed the descriptions are divided into frameworks constructed from crustose coralline algae and those constructed from branching corallines crustose frameworks are briefly described and illustrated from the miocene of malta recent coralligene from the mediterranean eocene reefs from spain recent algal reefs of st croix u s virgin is and algal reefs from bermuda branching frameworks are briefly described and illustrated from the recent maerl of the ne atlantic recent mud mounds from florida recent algal reefs from st croix and recent algal ridges on pacific reefs crustose and branching frameworks show an increase in strength of construction early submarine cements and macro borers and a decrease in erodibility from low to high energy environments the occurrence of genera in coralline frameworks is primarily controlled by their geographic and water depth ranges the construction of coralline frameworks is seen as the result of competition for living space on shallow marine hard substrates

origin of structural arcs of the carpathian balkan region burtman vs 1986 origin of structural arcs of the pat an balkan region in l p zonenshain editor tectonics of the eurasian fold belts tectonophysics 127 245 260 the late cretaceous reconstruction shows that the inner zones of the west east and south carpathians were adjacent to the dinarides and hellenides at that time forming together with them a linear fold system with bilateral vergence this fold system had a northwest strike in paleogene early miocene times the general deformation of the given part of the alpine belt took place it was caused by rotation of its asia minor balkan part relative to the more northern part of the belt this rotation 30 40 counter clockwise was accompanied by a shortening of the considered segment of the alpine belt by 30 hence exfoliation of the carpathian pontide and dinaric tauride branches of the alpine belt from each other and their disharmonious plastic deformation resulted in the formation of the aegean and tauride structural arcs and the carpathian structural loop during formation of the carpathian loop the gemeric tatric tectonic block moved northwards along the pemrinic oceanic substratum and rotated over 90 counter clockwise relative to the eastern alps

deformation of two phase systems with contrasting rheologies abstract rheological model experiments are used as analogues for foliation development in quartz mica rocks in a regime of pure shear in situ observations involving ice containing varying proportions and distributions of naphthalene and camphor illustrated two contrasting types of behaviour a matrix controlled versus a particle controlled deformation the matrix controlled deformation accommodates shortening predominantly by intracrystalline slip in the ice accompanied by some recrystallization while the more rigid naphthalene plates undergo rotation and mechanical alignment where shortening is normal to an initial platelet preferred orientation the foliation is enhanced and the matrix material aggregates between the rigid plates whereas a conjugate foliation is produced during shortening parallel to an initial platelet preferred orientation during particle controlled deformation strain is localized in particle concentrates the matrix areas and particles isolated in the matrix show little deformation at shortenings 10 dissolution of selected particles is achieved through an artificial fluid transport mechanism to create voids further shortening does not create closure of the fluid filled holes where shape is supported by the rigid matrix

the eigenvalues of steady flow in mohr space abstract the eigenvalues of the velocity gradients tensor and of the position gradients tensor describing instantaneous flow or incremental deformations are easily determined in mohr space as the points of intersection between a mohr circle and the horizontal mohr axis intersections occur only if the tensor has real eigenvalues eigenvectors associated with the eigenvalues are directions of no rotation a line of material particles under an eigenvector does not rotate during steady flow although the line is instantaneously stretching at a rate equal to its corresponding eigenvalue for non spinning steady sub simple shearing there will always be two eigenvectors the angle between the eigenvectors is dependent on the ratio of pure to simple shearing rates this angle decreases as the pure shearing component decreases relative to the simple shearing component superimposed increments of pure shear and simple shear produce an equivalent set of non rotated material lines but the deformation histories of these lines are rotational the influence of eigendirections on geological structures is constrained by the rheology of a rock during deformation in homogenous steady flow no influence may be obvious spatially periodic material softening along eigenvectors during bulk hardening may result in a complex fabric of intersecting shear zones the geometry of the fabric elements provides important information on the bulk deformation of the rock particularly on the bulk shear sense

progradational sequences in miocene shoreline deposits southeastern caliente range california abstract an exceptionally well exposed marine nonmarine transition in middle miocene strata exists in the southeastern caliente range california about 50 individual progradational sequences form a succession that ranges in thickness from approximately 1000 m where predominantly nonmarine to more than 2500 m where predominantly marine paleogeographic evidence in basalt flows near the top of the succession and in overlying fluvial deposits indicates that these middle miocene strata were deposited across a north northwest trending shoreline a complete progradational sequence typically is several meters to a few tens of meters thick and includes strata that represent three intertonguing stratigraphic units individual sequences generally rest on a thin gravel deposit interpreted as a transgressive lag on an erosional surface the gravel is overlain by structureless siltstone or fine grained sandstone deposited at water depths where the rate of faunal mixing exceeded that of production of structures by physical processes these rocks grade upward into bedded fine sandstone deposited closer to shore where physical processes exceeded bioturbation crossbedded lenses of coarse sand or fine gravel in the upper part of this facies suggest the presence of fairly long period surface waves the bedded fine sandstone is sharply ove lain by a cross bedded coarse sandstone facies that is interpreted as a combined offshore bar rip channel surf zone assemblage cross strata dip dominantly offshore suggesting substantial deposition from rip currents a secondary shoreparallel mode of cross strata direction suggests longshore currents produced by surface waves from the northwest the crossbedded coarse grained sandstone grades upward into planar bedded medium grained sandstone that is interpreted as a beach foreshore this facies grades upward through structureless medium grained sandstone into nonmarine or lagoonal red and green mudstone of the caliente formation the middle miocene succession was deposited in a subsiding basin that was otherwise remarkably stable tectonically the position of the strand line differed no more than a few kilometers through a period of 1 to 3 m y the average duration of the transgressive regressive cycles a few tens of thousands of years together with their distribution in groups of three or four in the lower two thirds of the succession is consistent with the pattern of long term climatic cycles produced by periodicity of the earth s solar orbit and may be related to eustatic sea level changes attendant to the development of the antarctic ice cap changes in the pattern of progradation in the upper part of the succession and nearby basaltic eruptions may have been precursors to the onset of movement along th san andreas fault in this area 12 14 m y ago

architectural complexity of a carbonate transgressive systems tract induced by basement physiography three dimensional exposure of the plio pleistocene calcarenite di gravina formation around matera horst italy permits analysis of the architecture and internal complexities of carbonate sedimentary bodies around a palaeoisland spatial organization of the different lithosomes along with their skeletal composition sedimentary structures and bedding patterns helps decipher the key factors that controlled platform architecture and distribution of heterogeneities basement physiography type and loci of carbonate production bottom currents and changes in accommodation relative sea level changes resulted from high frequency glacioeustatic cycles that punctuated an overall tectonically induced transgression topographic relief fragmentation of the limestone basement and wave energy controlled lithoclastic supply basement physiography and relative sea level changes determined the area available for carbonate producing biotas and thus the amount and type of skeletal sediments on the moderately dipping south western margin waves and associated currents re distributed the lithoclasts derived from coastal abrasion bioclasts mostly derived from epiphytic seaweed production in the shoreface infralittoral prisms resulted from downdip transport progradation and longshore transport which controlled along strike continuity of the prisms where basement continuity was interrupted at the margin of the palaeoisland a lithoclastic fan was deposited from dumping sediments carried by shore parallel currents fan shaped skeletal bodies coalesced to form an apron on the steeper northern side of the palaeoisland when a structural platform was flooded and epiphytic carbonates were shed red algae contribution depended on the available oligophotic area which in turn was controlled by high frequency sea level cycles basement physiography and apron aggradation the internal architecture of this apron resembles a low stand wedge but it accumulated during transgression deeper water contour parallel currents formed a lithosome at the foot of the structural relief interpreted as drift deposits it is composed of shallow water benthonic skeletal components planktonic foraminifera and some limeclasts

lateral heterogeneity in the upper mantle beneath the tibetan plateau and its surroundings from ss s travel time residuals 1 we use ss s differential travel times to map the upper mantle structure of the tibetan plateau and its surroundings new observations from analog stations in the former soviet union help to fill in gaps in the spatial coverage of previous studies providing new data for eastern tibet the kunlun range and the tarim basin the effects of crustal thickness variations anisotropy and global heterogeneity are evaluated and explicitly accounted for by incorporating results of previous studies and by ray tracing through a global 3d model the resulting residuals suggest that with the exception of the eastern part of the plateau tibet is underlain almost entirely by lithosphere of normal to greater than normal thickness in general there appear to be strong lateral gradients in wave speed between eastern and western tibet we find little evidence for low wave speeds under northern tibet to the west of about 87 e instead the average shear wave speeds in the upper 300 km of the mantle beneath this part of tibet are about 0 5 km s faster than those directly to the north beneath the tarim basin these results support models of tibetan dynamics in which the lithosphere underlying northern tibet underplates the crust as opposed to those in which large portions of this lithosphere disappear by convection subduction or detachment at the same time the dominant e w gradient in residuals implies that 2d models inadequately explain the dynamics of all of tibet

a scanning electron microscope technique for identifying the mineralogy of dust in ice cores dust particles in an ice core from east rongbuk glacier on the northern slope of qomolangma mount everest 28 01 n 86 58 e 6518 m a s l central himalaya have been identified as mica using a combination of scanning electron microscope based techniques and energy dispersive x ray spectroscopy to identify the elements present and electron backscatter diffraction to identify the crystal type this technique for identifying individual crystalline dust particles in samples of glacial ice could be especially useful in the future for identifying water soluble crystals in ice for studying the strain history glaciotectonics of basal ice or in studies of ice mica composites used as analogs of quartz mica rocks

foliation and strain development in ice mica models abstract the behaviour during experimental deformation of composite foliated rock models composed of ice and ice mica is described in order to replicate deformation in quartz mica rocks the deformation involves pure shear and a component of simple shear oblique to the shortening axis a foliation is developed which is defined by an alignment of micas and a preferred orientation of airbubbles that closely parallels the principal plane of the local finite strain ellipsoid the degree of mica re alignment is not purely dependent on a parameter such as strain but is also controlled by the nature of the initial mica fabric and the orientation of layering relative to the shortening direction where there is some obliquity of a primary layering to the bulk shortening direction the deformation is markedly inhomogeneous with non uniform extension parallel to the flow direction over short distances this results in varying local strain and mica distributions values of strain obtained from such mica orientation distributions are always less than the observed finite strain and are therefore incompatible with a march model however deformation of an initial layering parallel to the shortening direction that contains a uniform mica distribution results in a homogeneous finite strain distribution and the mica distribution strengthens parallel to the principal plane of the local strain ellipsoid this mica distribution produces values of strain that correspond to the predictions of the march model in contrast deformation of initial bimodal fabrics or fabrics asymmetric to the shortening direction will develop strong preferred orientations quicker than an initial uniform distribution and characteristics of the initial fabric pattern always persist within the deformed mica preferred orientation shortening perpendicular to a strong initial preferred orientation only strengthens the mica fabric intracrystalline slip in the ductile ice matrix is the main means of accommodating the deformation and also produces a strong c axis preferred orientation grain boundary mobility in the ice is retarded by the dispersed mica phase however grain growth during and post dating deformation does not effect mica orientation distributions these features resemble and are compared with identical structures observed in many quartz mica rocks

time for anisotropy the significance of mechanical anisotropy for the development of deformation structures hr acknowledges financial support by the china scholarship council csc grant nr 201506400014 egr acknowledges the support of the beatriu de pinos programme of the government of catalonia s secretariat for universities and research of the department of economy and knowledge 2016 bp 00208 we thank bruce hobbs and an anonymous reviewer for their suggestions to improve this article

brittle deformations in the upper pleistocene deposits of the crotone peninsula calabria southern italy abstract the structural setting of the crotone peninsula calabria southern italy is discussed in this paper structural analyses were carried out both on a regional and an outcrop scale to detect the main structural systems and the stress field which affected the area during the late pleistocene the tectonic features observed in the area are represented by normal faults and extensional joints the regional scale faults are arranged in five main systems striking ene wsw nne ssw e w nw se and nnw sse they are responsible for the dislocation of four marine depositional units cutro terrace correlatable with the isotopic stage 7 s leonardo campolongo isola di capo rizzuto terrace correlatable with the isotopic substage 5e le castella capo rizzuto terrace correlatable with the isotopic substage 5c and capo colonne terrace correlatable with the isotopic substage 5a in several distinct terraces from the studies carried out on a mesostructural scale it is possible to conclude that for the last 200 000 yrs the crotone peninsula was affected by an extensional stress field the comparison between the average uplift rates calculated for the crotone peninsula terraces and those computed for several upper pleistocene deposits located in sicily calabria and campania suggests that the intense tectonics which affected the crotone peninsula can be related to the geodynamic activity of the calabrian arc

teleseismic shear wave splitting and deformations in central europe abstract we analyse the results of measurements of shear wave splitting due to azimuthal anisotropy in the upper mantle of central europe based on the sks technique the observations at seismograph stations in the eastern part of germany are combined with the published estimates of the parameters of azimuthal anisotropy at neighbouring locations these data are interpreted in terms of lattice preferred orientation of olivine which is caused by deformations in the upper mantle directions of polarization of the fast wave counted clockwise from north change from 50 70 in the western part of the region to 100 120 in the eastern part these directions are close to the trend of the hercynian fold belt and might suggest that anisotropy is frozen in the subcrustal lithosphere however the observed traveltime delays between the split waves are generally too large to be easily reconciled with the thermal and seismic estimates of thickness of the subcrustal lithosphere underneath central europe

kinematic and metamorphic aspects of cleavage formation in very low grade metamorphic slates abstract fabric studies on first cleavages in very low grade metamorphic slates from the rheinisches schiefergebirge and other very low grade metamorphic fold belts reveal two types of slaty cleavage 1 1 cleavage without syntectonic phyllosilicate recrystallization these are generally crenulation cleavages 2 2 cleavage with syntectonic phyllosilicate recrystallization with increasing syntectonic metamorphism the crenulation fabric is modified by solution of grains along cleavage planes and precipitation of material within the cleavage lamellae with further increase of metamorphism the crenulation fabric is gradually obliterated the finite fabric results from progressive solution crystallization and recrystallization superimposed with bending kinking and internal rotation achieved by slip parallel to the basal planes of phyllosilicates

submerged late pleistocene reefs on the tectonically stable s e florida margin high precision geochronology stratigraphy resolution of substage 5a sea level elevation and orbital forcing abstract a well preserved submerged in situ fossil reef tract lies offshore of the southeast florida carbonate margin in the florida keys cores in two transects enabled reconstruction of reef stratigraphy and paleoenvironments paleo water depths and paleo sea levels because florida is tectonically stable the elevation data required correction only for the known minor subsidence rate twenty eight pristine aragonitic corals were dated via high precision tims u series methods to produce a comprehensive late pleistocene and early holocene geochronology the pleistocene section of the fossil reef includes a thick section of substage 5a reef growth recorded from 15 to 11 m msl spanning an age range of 86 2 80 9 ka paleoenvironmental reconstruction local water quality constraints and elevations of concurrent bahamian speleothem growth combine to limit sea level to 9 0 m msl at 83 ka this coincides unlagged with the 82 ka 65 n july insolation peak the absence of any lag suggests that the earlier peak in obliquity at 92 ka also controls paleoclimate and sea level a below present sea level estimate for substage 5a from the florida fossil reef data coincides more closely with uplift corrected reef data estimates of 15 to 13 m msl from tectonic margins such as barbados and haiti than with higher than present sea levels derived from detrital corals from bermuda and the u s atlantic coastal plain the best tims dates on corals and speleothem constraining sea level combine to produce a new regional sea level curve for the atlantic caribbean region for late isotope stage 5 and early stage 4

rip currents as a geological tool this paper considers the nature and sedimentary significance of rip currents rip currents are the main factor responsible for the transport of coarse sediments from the littoral zone to greater depths such sediments deposited outside the zone of wave deformation may be identified as storm rip current increments within sediments deposited during fair weather composite beds deposited during a given wave cycle by storm rip currents are closely similar to turbidites and many so called fluxo turbidites described from flysch deposits using data gathered in studies conducted on the modern baltic coast supplemented by experimental work and theoretical considerations a sedimentary model is proposed the model may be used to interpret possible rip current deposits among shallow water turbidites and both modern storm sediments and ancient tempestites language en

micro and meso scale deformation structures in experimental fault zones abstract kinematic structures of brittle brittle ductile and ductile shear zones were developed in experimental simple shear deformation transparent films of paraffin wax with different initial fabrics were progressively deformed in a manually driven stage mounted shear apparatus producing heterogeneous simple shear 0 36 2 64 at variable strain rates of from 3 3 10 5 to 4 08 10 5 s 1 en echelon fracture arrays compressive and tensile bridges spaced cleavage stylolite like cleavage and sigmoidal cleavage trails were developed in brittle and brittle ductile deformation structures produced in ductile experiments were c s and c s fabrics and type asymmetric tails shear lenses and active folds of pre existing and induced anisotropy planes the experiments offer insight into the microstructural processes involved and demonstrate development of a progression of shear structures in a single non steady deformation

the origin of kinks in polycrystalline ice abstract in situ observations of events leading to development of kink hands kbs and kink band boundaries kbbs and changes in their morphology are recorded during the deformation of layered polycrystalline ice at temperatures above 10 c slip on 0001 preceeded kb initiation and two different mechanisms a shear mode and a buckling mode are proposed for the development of the observed kbs the shear mode occurs with axial compression parallel to 0001 and is restricted to a band of material with sharply defined kbbs involved with an effective macroscopic simple shear sub perpendicular to the slip plane during deformation these bands progressively reduce their width while maintaining a stable orientation secondary kbs and microfractures are propagated within the kb as a result of increasing shear deformation in the band these phenomena are attributed to a limiting of the shear deformation to a band and the necessity to accommodate the dilatation changes in the buckling mode kb initiation is preceeded by the formation of deformation bands and this type of kb can initiate from inherent heterogeneities within the grain aggregate microstructural sensitivity is put forward to explain the apparent instability of this type of kb which is often curved and capable of migrating through a crystalline lattice the buckling mode occurs in grains where 0001 is oblique to the compression direction

a proposal for the kinematic modelling of w dipping subductions possible applications to the tyrrhenian apennines system in w dipping subduction zones there is a general eastward progression of the back arc basin accretionary wedge foredeep complex with the forward progression early stages of the complex are revealed by slices of upper crust and sedimentary cover abandoned to the west left floating above a new section of mantle a major shear zone should form at the new moho separating upper crust slices of earlier accretionary stages and the eastward flowing mantle the mantle wedging at the top of the subduction plane could be responsible for the uplift of the central parts of the belt the retreating of the subduction hinge is interpreted as due to the push generated by the eastward mantle flow detected in the hot spot reference frame the foredeep depth is mainly a function of the radius of curvature of the subduction hinge the frontal wedge is constructed from the stacking of the upper layers of the subducting plate and the syntectonic clastics that fill the foredeep which are progressively involved in thrusting and later by extension in order to preserve volume balance the lithosphere of the eastern plate before subduction has to be the same size as that which has been subducted due to the longer length of the arc with respect to the original length of the linear margin between the two converging plates laterally stretched subducted lithosphere is predicted at depth w dipping subductions usually have a short life probably due to their inherent capability to produce new lateral heterogeneities of the lithosphere the thin back arc which are a key factor in controlling and generating new subductions both e and w dipping this model is applied to the apennines tyrrhenian sea system

lattice rotation in polycrystalline aggregates and single crystals with one slip system a numerical and experimental approach abstract in this study lattice rotations in polycrystals and single crystals with one slip system have been analysed for pure shear and simple shear by re visiting previously published data and by conducting new numerical models that are compared with results from experiments on polycrystalline ice the numerical models are based on the finite difference method and on the assumption that dislocation glide on one slip system is the dominant crystalline deformation mechanism and is controlled by the critical resolved shear stress law such a deformation scheme corresponds to the operation of glide on 0001 in polycrystalline ice used in the physical deformation experiments the results show that lattice rotation is primarily controlled by the bulk deformation kinematics in both the polycrystalline aggregates and the single crystals in the single crystals the lattice rotation is entirely consistent with the vorticity of the bulk deformation kinematics whereas in the polycrystalline aggregates extensive grain interactions significantly modify the local lattice rotations and may even lead to the lattice planes of individual grains rotating in an opposite sense to that of the bulk deformation these results can reasonably explain the development of crystallographic preferred orientations widely reported in the literature

on the relation between seismic anisotropy and finite strain because seismic anisotropy in the upper mantle is due primarily to lattice preferred orientation lpo of olivine crystals induced by deformation observations of anisotropy can provide constraints on mantle deformation and flow in this paper we use a previously published theory for deformation induced lpo ribe and yu 1991 to quantify the relation between seismic anisotropy and deformation for two model compositions a pure olivine dunite aggregate and a harzburgite comprising 70 olivine and 30 enstatite analytical and numerical solutions of the governing equations show that the predicted lpo and hence also the seismic anisotropy depends only on the finite strain and not on the deformation path by which that strain is produced the magnitude of the anisotropy depends only on the ratios c1 c2 and c2 c3 where c1 c2 c3 are the lengths of the principle axes of the finite strain ellipsoid and the directions of maximum and minimum compressional wave velocity vp coincide with the axes c1 and c3 respectively we calculate the percent anisotropies for compresional and shear waves propagating along the three principle axes of the finite strain ellipsoid as functions of the axial ratios c1 c2 and c2 c3 for our two model compositions however inferences of the magnitude of finite strain obtained using these results are likely to be minimum estimates because our theory neglects the effects of dynamic recrystallization finally we present as a byproduct of this study a new direct method for calculating the finite strain produced by an arbitiary deformation history

storm and tide dominated shorelines in cretaceous moosebar lower gates interval outcrop equivalents of deep basin gas trap in western canada the moosebar and gates formations crop out in the deformed foothills belt south of fort st john british columbia they permit examination of the depositional environments of sandstones and conglomerates that are gas bearing in the equivalent wilrich falher interval of the deep basin of alberta and british columbia the moosebar gates interval consists of several upward coarsening and marine to nonmarine sequences moosebar bioturbated shales pass upward into turbidites and offshore storm deposits flow directions indicate a north dipping paleoslope a second coarsening upward sequence at the top of the moosebar and base of the gates terminates in a lenticular fluvial conglomerate up to 30 m thick which is overlain by coals carbonaceous mudstones and sandstones above the carbonaceous zone a major lateral facies change is observed fluvial conglomerates in the south grade into beach conglomerates northward the upper part of the beach conglomerate consists of exposed three dimensional storm berms at least 500 m long up to 1 5 m high with wavelengths of 12 to 24 m the berms trend east west seaward of the conglomerate beach are herringbone cross bedded tidal sandstones with a marine trace fauna graded sharp based conglomerates also are present probably washed out to sea by storms farther north at the same stratigraphic level is a series of partly overlapping conglomerate bars up to 5 m thick and 40 to 50 m across the tops of these bars are covered with storm formed symmetric conglomeratic dunes details of the orientation and geometry of these conglomerate bodies along with their internal structure and pebble fabrics suggest that four major environments fluvial beach offshore conglomerate bars and offshore graded storm conglomerates should be identifiable and predictable in the subsurface

seismic constraints on dynamics of the mantle of the kaapvaal craton abstract shear wave splitting in the upper mantle of the kaapvaal craton in southern africa is measured by applying the sks technique to the records of a portable array of digital broad band seismographs the data are interpreted in terms of lattice preferred orientation in olivine fast wave polarization directions at all stations of the array are close to the absolute plate motion apm direction of southern africa since the end of the jurassic this alignment is similar to that previously reported for the north american craton and suggests that the large scale component of mantle anisotropy on both sides of the atlantic can be related to resistive drag at the base of the plates a likely depth range of the corresponding deformation is 150 400 km analysis of the mantle converted phases suggests that the high velocity mantle root of the kaapvaal craton which translates coherently with the plate resides in the same depth range the bottom of the root is found at a depth close to 380 km we conclude that the root is deformed by the recent plate motion but the deformations are not strong enough to be seen in the available tomographic models

variation in fold geometry in the yuso basin northern spain implications for the deformation regime first generation structures in greywackes of the yuso group from the cantabrian mountains of northern spain show a distinct variation in geometry with depth in a regional synclinal structure curavacas and lechada synclines they are easily distinguished from other deformation events in the structurally uppermost level we find flap folds flap folds are recumbent structures with the inverted limb preserved below this level cascade folds are found these structures have a vergence opposite to that of parasitic folds the nomenclature adopted is from harrison and falcon characteristically these structures have shallowly dipping axial surfaces in agreement with the shallow dip of the axial plane regional cleavage in the lowermost structural level upright parasitic folds with a steep cleavage are present the variation in fold geometry is accompanied by a general steepening of the regional cleavage with increasing depth in the absence of overprinting relationships the f1 fold geometries are included in a single deformation event the steepening of the cleavage with depth reflects the change in orientation of the maximum shortening direction from sub vertical in the upper part of the syncline to sub horizontal in the lower part with increasing depth the deformation regime during f changed from bending to buckling the deformation regime on the regional scale however is associated with basement subsidence and passive formation of the regional synclinal structure furthermore the absence of a distinct microfabric for the different f1 folds indicates that on a small scale a similar deformation regime was present we conclude therefore that the scale at which we study a structure only reflects the deformation regime at that particular scale consequently the overall deformation regime cannot be determined from single outcrops or microstructural analysis alone

sequence stratigraphy and architectural variability in growth fault bounded basin fills a review of plio pleistocene stratal units of the crotone basin southern italy field examples from the pliocene to pleistocene succession of the crotone basin document the variability of stratal architecture in syntectonic units deposited in normal fault bounded basins relatively thick trangressive intervals are common within these successions as shown in the zinga 2 zinga 3 and strongoli stratal units transgressive packages are formed by lagoonal mudstones that are abruptly overlain by shoreface sandstones aggradational highstand shallow marine packages are typical of the lower pliocene succession in half graben basins these deposits resulted from balanced conditions between the rate of sediment supply and the rate of creation of accommodation relatively thick forced regressive deposits are common within basins during phases where the accommodation supply ratio is low e g the middle pleistocene san mauro sandstone these deposits influenced by growth faulting and folding recorded base level lowering linked to glacio eustasy a complex stratal architecture may be the consequence of the alternation between tectonic subsidence and uplift e g the serra piani stratal unit such variations are thought to be related to the onset of an earliest mid pliocene transpressional tectonic phase the studied deposits therefore show a marked tectonic control that strongly influenced their stratal architecture these examples represent interesting cases of sequence stratigraphic analysis in growth faulted contexts

the ephemeral development of c shear bands a numerical modelling approach abstract c shear bands are ubiquitous structures in shear zones but their development is poorly understood previous research has determined they mostly occur in rocks with a high mechanical strength contrast using numerical models of viscoplastic deformation we studied the effect of the proportion of weak phase and the phase strength contrast on c shear band development during simple shearing to a finite strain of 18 we found that c shear bands form in models with 5 weak phase when there is a moderate or high phase strength contrast and they occur in all models with weak phase proportions 15 contrary to previous research we find that c shear bands form when layers of weak phase parallel to the shear zone boundary rotate forwards this occurs due to mechanical instabilities that are a result of heterogeneous distributions of stress and strain rate c shear bands form on planes of low strain rate and stress and not in sites of maximum strain rate as has previously been suggested c shear bands are ephemeral and they either rotate backwards to the c plane once they are inactive or rotate into the field of shortening and thicken to form x and triangle shaped structures

shear bands crenulations and differentiated layering in ice mica models abstract thin sheets of composite ice mica have been deformed in order to simulate the development of cleavages in quartz mica rocks a strong initial mica preferred orientation was variably oriented to the shortening direction deformation parallel to the foliation results in a crenulation type cleavage developing from shear bands initiated after a component of pure shear deformation oblique to the foliation produces a differentiated cleavage and involves a large component of shear strain subparallel to the original anisotropy the strain is accommodated by intra and intercrystalline processes that produce extensive grain elongation and rearrangement of the ductile matrix thereby forming ice vs mica rich regions on the other hand there is no drastic morphological change when a sample is shortened perpendicular to an original foliation that is where the micas lie in the plane of no shear strain instead the mica fabric is strengthened and the grains in the ductile matrix are flattened two models are presented for the initiation propagation and evolution of the observed crenulation versus differentiated cleavage types these depend on mica stacking and orientation relative to the transverse properties of the sample and also on the direction of anisotropy to the xy plane of the bulk strain ellipsoid the models invoke shear on planes of high shear strain and rotation of the shear bands and rigid mica grains into a direction approximately parallel to the bulk extension direction

mineral fish their morphological classification usefulness as shear sense indicators and genesis mineral fish are sheared and commonly asymmetric mineral grains or clusters of grains this work reports 11 sub types of mineral fish showing a top to se sense of ductile shearing in the karakoram metamorphic complex kmc the mineral fish are of three broad geometries sigmoid lenticular and parallelogram reliable senses of shear are indicated by the overall asymmetry and inclination of mineral fish on the other hand the true shear sense is not always indicated by either the orientations of their cleavage planes or those of the individual grains in composite mineral fish the ranges of local orientations of single sigmoid mineral fish that include the lower values 23 in the kmc indicate their extensive ductile shearing the studied mineral fish were products of a range of deformation mechanisms including homogeneous deformation simple shear intra granular slip crystal plastic deformation fracturing and synthetic shearing additionally some examples might have undergone duplex slips and a few nucleated and grew either prior to or during the top to se shearing

the concept of steady state foliation abstract a steady state foliation is thought of as a foliation with constant orientation and intensity in a rock undergoing steady state flow the problem discussed is whether such straininsensitive foliations exist in rocks and how they might be distinguished from the more familiar strain sensitive foliations steady state foliations would be useful indicators of stress or of strain rate yet misleading if used as indicators of finite strain one requirement for maintenance of steady state foliations is operation of processes that locally weaken grain shape preferred orientation or reduce grain aspect ratios or destroy lithological layering during flow these are the inverses of the processes normally discussed in connection with foliation development many such processes are known though the details of how and when they operate efficiently enough to stabilize a foliation are unknown there is however a tendency for some of them to operate more efficiently at high strains high temperatures and in flow regimes with high vorticity natural and experimental high temperature shear zones are accordingly one environment in which steadystate foliations may be encountered an experiment is described in which a thin specimen of para dichlorobenzene was given a large shearing deformation at 90 of its absolute melting point a steady state foliation was not produced but the technique is a promising one for further microstructural studies where in situ observation of material undergoing large deformations is desirable

rheology of the lithosphere selected topics we review recent results concerning the rheology of the lithosphere with special attention to the following topics 1 the flexure of the oceanic lithosphere 2 deformation of the continental lithosphere resulting from vertical surface loads and forces applied at plate margins 3 the rheological stratification of the continents 4 strain localization and shear zone development and 5 strain induced crystallographic preferred orientations and anisotropies in body wave velocities we conclude with a section citing the 1983 1986 rock mechanics literature by category

shear wave splitting in the records of the german regional seismic network estimates of the parameters of shear wave splitting in the records of sks and skks of the new german regional seismograph network grsn for one layer model show large azimuthal variations at some stations of the network it is found that the variations are compatible with the presence of two anisotropic mantle layers in the region of the south german triangle sgt the fast direction in the upper layer is between n s and ne sw close to the previously reported estimates of the fast direction in the sub crustal lithosphere of the sgt the fast direction in the lower presumably asthenospheric layer is close to e w the estimates of the effective fast direction for one layer model at the stations of the grsn confirm the previously noted tendency of the fast direction of mantle anisotropy in central europe to change from 50 70 in the western part of the region to 100 120 in the eastern part a correlation of this change with a bending of the present day direction of maximum horizontal stress in the crust suggests that anisotropy in the asthenosphere of central europe can be related to the alpine orogeny

the interaction of deformation and metamorphism in slates abstract the distribution microchemistry and internal structure of phases present in a slate are reported and used as a basis for a discussion of the interaction between deformation and metamorphism in slates the study reveals details of the interactions between mechanical and chemical processes involved in slaty cleavage evolution evidence for the involvement of mechanical rotation solution and crystallisation recrystallisation and metamorphic reactions is presented and amalgamated into a model of cleavage development the model involves a synchronous variation in the type location and rate of cleavage evolution processes and a change in the importance of particular processes during the total history the early stages of cleavage development are dominated by mechanical rotation associated with crenulation and possibly accompanied by grain boundary sliding and solution processes later stages of cleavage evolution are more heterogeneous and occur by a complex interaction of deformation and metamorphic growth processes which are concentrated at the interfaces between domains generated earlier in the strain history the variations in grain chemistry and orientation together with changes in the strain rate or stress level are suggested to control the different deformation behaviour of different grains along these strain accommodation zones and to dictate whether grains bend kink dissolve recrystallise or react and undergo growth evidence for the involvement of reactions ranging from ionic exchange to crystallisation from solution and solid state reordering is presented and the influence of deformation on the location and rates of these reactions discussed approximately ten potential reactions are involved in the cleavage evolution of the slate studied the model presented incorporates these reactions into the deformation processes and accounts for the concentration of phengite and iron poor chlorites in to one microstructural domain and paragonite quartz and fe rich chlorites into the other domain two transformations appear to be fundamental in the slate studied 1 1 the transformation of illite to phengite 2 2 the transformation of fe rich chlorite to fe poor chlorites and both can be related to particular responses of grains to the reorientation processes at domain interfaces

the port mouton shear zone intersection of a regional fault with a crystallizing granitoid pluton abstract the peraluminous tonalite monzogranite port mouton pluton is a petrological geochemical structural and geochronological anomaly among the many late devonian granitoid intrusions of the meguma lithotectonic zone of southern nova scotia the most remarkable structural feature of this pluton is a 4 km wide zone of strongly foliated 040 subvertical monzogranites culminating in a narrow 10 30 m straight zone of compositionally banded rocks that extends for at least 3 km along strike the banded monzogranites consist of alternating melanocratic and leucocratic compositions that are complementary to the overall composition of that part of the pluton suggesting an origin by mineral melt and mineral mineral sorting biotite and feldspar are strongly foliated in the plane of the compositional bands these compositional variations and foliations originated by a process of segregation flow during shearing of the main magma with a crystallinity of 55 75 subsequent minor brittle fracturing of feldspars twinning of microcline development of blocky sub grains in quartz and kinking of micas demonstrate overprinting by a high temperature deformation straddling the monzogranite solidus small folds and late sigmoidal dykes indicate dextral movement on the shear zone this port mouton shear zone pmsz is approximately co linear with the only outcrops of late devonian mafic intrusions in the area two of which are syn plutonic with well developed mingling textures in the marginal tonalite of the port mouton pluton also closely co linear with the mafic intrusions are a granitoid dyke that extends well beyond the outer contact of the port mouton pluton a swarm of large aligned angular xenolithic slabs a zone of thin wispy schlieren banding a large be bearing pegmatite and a breccia pipe with abundant garnetiferous metapelitic xenoliths in various ways the shear zone may control all of these features the port mouton shear zone is parallel to many other ne trending faults and shear zones in the northern appalachians probably related to the docking of the meguma zone along the cobequid chedabucto fault system

thinning of the upper mantle during late paleozoic appalachian orogenesis across the appalachian orogen of new england the splitting of core refracted shear waves from a wide range of arrival directions indicates the presence of two nearly uniform horizontal layers of anisotropic upper mantle the anisotropy in the lower layer has a fast axis nearly parallel to the absolute motion of the north american plate and thus is attributed to basal shear as the plate plows through asthenospheric mantle the anisotropy of the upper layer is inferred to be a fossil fabric residing in lithospheric mantle the finite extension direction of the upper fabric is subhorizontal and oriented normal to the local trend of the appalachian orogen the upper fabric is consistent over a broad region beneath and west of the new england appalachians which indicates that it formed after devonian closure of the iapetus ocean probably during or after the paleozoic acadian and alleghany orogenies tectonic scenarios for synconvergent or postconvergent extension developed for tibet predict rapid surface uplift and increased heat flow due to lithospheric thinning consistent with coeval late orogenic mantlederived magmatism in both the northern appalachians and morocco

raised pleistocene marine terraces of the crotone peninsula calabria southern italy facies analysis and organization of their deposits abstract wide marine terraces well known in the italian literature are present in the crotone peninsula ionian calabria they are related to the interplay between pleistocene sea level changes and the progressive uplift of the calabrian arc from the middle pleistocene onwards we present a description of facies organization and stratigraphical characteristics of the terrace deposits along with a new geological map of the area all the marine terraces unconformably overlie a plio pleistocene slope succession known as cutro clay the oldest and highest terrace named cutro terrace is placed between 90 and 200 m of elevation and is gently inclined south eastwards four younger terraces placed at progressively lower elevations and dipping seawards at low angles have been recognized the sedimentary deposits of the terraces are represented by mixed carbonate and siliciclastic bodies up to 10 m thick algal reefs and grainstone to rudstone deposits are common in the south eastern part of the study area whereas mostly siliciclastic sandstone units of shoreface environments are more abundant northwards and westwards the deposits of some terraces are made up of minor cycles bounded by subaerial transgressive and flooding surfaces referred to minor sea level fluctuations nne ene e and wnw trending normal fault systems are present within the study area and dissect the marine terraces specifically the activation of ene trending faults took place after the formation of the oldest terrace but prior to the formation of the younger terraces

geometry classification and kinematics of s c and s c fabrics in the mushandike area zimbabwe planar fabrics in small dextral shear zones in the mushandike area of the zimbabwe archaean craton consist of a sigmoidal primary foliation s displaced by discrete shears c or c these planar fabrics can be divided into porphyroclastic megacrystic and banded types depending mainly on the values of the angles between s and c or c surfaces the structures that define s surfaces and the spacing of c or c surfaces the values of the angles between the foliations are proposed as the basis for a general classification of planar fabrics in shear zones the values of the angles depend on microstructures and strain microstructural evidence shows that slip did not occur on s surfaces but only on c or c surfaces a model for the development of the fabrics proposes that s surfaces lie parallel to the xy plane of the local finite strain ellipsoid in domains of simple shear between c or c surfaces c surfaces may form in the orientation of a coulomb failure surface the field evidence suggests that an increase in bulk strain is at least partly accommodated by an increase in local strain in domains between c or c surfaces as the s surfaces rotate with the local finite strain ellipsoid

asthenospheric flow beneath the carpathian pannonian region constraints from shear wave splitting analysis abstract systematic shear wave splitting sws study was conducted to illuminate the mantle deformation and dynamics in the carpathian pannonian region cpr where its tectonic mechanism is still enigmatic and actively debated we have obtained a total of 1170 sws measurements using seismic data recorded by 59 broadband seismic stations the resulting sws measurements mostly possess nw se fast orientations and are mostly oblique or even orthogonal to the trends of major geological features and the absolute plate motions spatial coherency of the splitting parameters reveals that the center of the observed anisotropy is most likely originated from the asthenosphere at the depth of about 250 km thus the uniformly nw se fast orientations is more likely to represent an asthenospheric flow which has partially or completely overprinted the anisotropic fabrics developed during the formation of the pannonian basin such an asthenospheric flow is regionally deflected along the edges of continental keels beneath the south carpathians and the vrancea zone where complex anisotropy is well determined and range parallel fast orientations are revealed based on two layered fitting of the sws measurements our results combined with previous sws measurements suggest that the revealed nw se asthenospheric flow is actually a key component of the toroidal flow induced by the adriatic subduction which dominantly promotes the current upper mantle deformations beneath the cpr and its adjacent regions

lithospheric thermal regimes in europe abstract the heat flow pattern of europe derived from more than 8000 observations is dominated by a general northeast to southwest increase in geothermal activity which is the consequence of the tectonic evolution of the whole continent this paper reviews the history of the geothermal mapping of europe and describes the recently compiled set of geothermal maps of europe surface heat flow is correlated with the age of the last tectonothermal event with the near surface heat production and with the crustal thickness deep temperature distributions within the crust lithosphere are calculated for 1 d 2 d and simple 3 d models characteristic temperature depth curves are given for some of the major tectonic provinces and the results of various techniques are compared the value of the crustal heat contribution is assessed and a regional moho heat flow pattern is proposed the mohorovicic discontinuity is clearly not an isothermal surface neither is the heat flow from below the crust constant

periodicity of mesoscale phanerozoic sedimentary cycles and the role of milankovitch orbital modulation data on more than 200 mesoscale sedimentary cycles indicate that phanerozoic cycle periods are randomly distributed with respect to the four major milankovitch orbital parameters except late mississippian through late pennsylvanian cycles which show positive clustering about the 413 000 yr eccentricity period cycle periods calculated from average thicknesses and accumulation rates are strongly dependent on the former correlation coefficient 0 802 but relatively independent of the latter correlation coefficient 0 360 hence calculated period is largely a function of average cycle thickness and milankovitch range periods will be preferentially calculated for cycles with average thicknesses between 1 m and 20 m regardless of actual causes of cyclicity for individual cyclic sequences arguments for milankovitch control based solely on average period are unfounded comparison of short term holocene sedimentation rates and long term phanerozoic accumulation rates for cyclic peritidal and delta

residual topography lithospheric structure and sunken slabs in the central mediterranean abstract the central mediterranean comprises subduction collision and backarc extension all in a relatively small area in this paper we analyze the topography of this region examining the influence of subducting slabs on overriding plates we take the observed surface elevation remove the contribution of the crust to it and use the residual topography to identify regions that are unusually low unusually high or normal then we calculate lithospheric thickness where local isostasy applies the results provide information about the structure of the lithosphere in this complex region and about the vertical tectonics in particular we found a difference between the south tyrrhenian subduction zone and the apennines consistent with the processes of slab rollback and slab break off respectively in the south tyrrhenian the edge of the oceanic plate is strongly pulled down whereas the edge of the overriding plate the calabrian peninsula is uplifted this opposite trend indicates weak plate coupling that is the subducting slab which is rapidly rolling back hangs almost entirely on the oceanic plate and the overriding plate is free in contrast in the apennines high residual topography and uplifting are detected on both sides of the mountain belt consistent with complete break off of the subducted lithosphere

incremental deformation and fabric development in a kcl mica mixture abstract the history of deformation and of mica reorientation is described in a kcl mica mixture in the middle of a kink like experimental shear zone the history was reconstructed by deforming several specimens to successively greater total strains and assuming the more deformed specimens passed through the states of strain and fabric exhibited by the less deformed specimens a pseudo differentiated layering is described which arises from the original network distribution of the mica grains without benefit of any differentiation process a comparison is made between the observed mica fabrics at various strains and those predicted by the march model taking the measured initial preferred orientation of the micas into account the actual reorientation processes in the material are found to be more efficient than the march transformation at shortening strains less than about 70 but less efficient at higher strains these departures from marchian behavior are explaned qualitatively comparison is also made between observed and predicted intensities of mica preferred orientation assuming a hypothetical random orientation of micas in the starting material for the march calculation

gravelly spit deposits in a transgressive systems tract the pleistocene higashikanbe gravel central japan the pleistocene higashikanbe gravel which crops out along the pacific coast of the atsumi peninsula central japan consists of well sorted pebble to cobble size gravel beds with minor sand beds the gravel includes large scale foreset beds 5 10 m high and overlying subhorizontal beds 0 5 3 m thick showing foreset and topset structure from which the gravel has previously been interpreted as deposits of a gilbert type delta however 1 the gravel beds lack evidence of fluvial activity such as channels in the subhorizontal beds 2 the foresets incline palaeolandwards 3 the gravels fill a fluvially incised valley and 4 the gravels overlie low energy deposits of a restricted environment such as a bay or an estuary the foresets generally dip towards the inferred palaeoshoreline indicating landward accretion of gravel reconstruction of the palaeogeography of the peninsula indicates that the higashikanbe gravel was deposited as a spit similar to that developed at the western tip of the present atsumi peninsula rather than as a delta according to the new interpretation the large scale foreset beds are deposits on the slopes of spit platforms and accreted in part to the sides of small islets that are fragments of the submerging spit during relative sea level rise the subhorizontal beds include nearshore deposits on the spit platform topsets and deposits of gravel shoals or bars which are reworked sediments of the spit beach gravels during a transgression the lack of spit beach facies in the subhorizontal beds results from truncation by shoreface erosion dome structure which is a cross sectional profile of a recurved gravel spit at its extreme point and sandy tidal channel deposits deposited between the small islets were also identified in the higashikanbe gravel the higashikanbe gravel fills a fluvially incised valley and occupies a significant part of a transgressive systems tract suggesting that gravelly spits are likely to be well developed during transgressions the large scale foreset beds and subhorizontal beds of gravelly spits in transgressive systems tracts contrast with the foreset and topset beds of deltas characteristic of highstand lowstand and shelf margin systems tracts

luminescence chronology of late pleistocene raised beaches in southern italy new data of relative sea level changes abstract littoral sediments forming terraces along the crotone peninsula coast southern italian have been investigated using sedimentological analysis and luminescence dating techniques and adopting assessments from previous work on fossil assemblages all sediment layers analysed were deposited in the nearshore environment between 20 m below and few metres above sea level during the falling sea level of a temperate warm climate interval the restoration of almost identical environmental conditions occurred in oxygen isotope substages 5e and 5a and in oxygen isotope stage 3 limits given by luminescence physics prevented accurate dating of the uppermost lying terrace former crotonian stage terrace and the presence of a substage 5c terrace is masked by the lack of suitable material for dating constraints on the positions of relative sea level from the reliable data set show that the sea level fell from 2 m during substage 5e to 29 m during substage 5a and then rose to 15 m during stage 3 observations for oxygen isotope stage 3 sea level at the crotone peninsula coast are inconsistent with those at the huon peninsula new guinea and in the western pacific the disagreement highlights the lack of knowledge concerning mediterranean thermohaline circulations and sea water exchanges between the atlantic and mediterranean seas during glacial cycles

azimuthal anisotropy in the earth from observations of sks at geoscope and nars broadband stations abstract we have analyzed observations of low frequency sks waves recorded on horizontal components at several broadband stations of the geoscope and nars arrays splitting of sks is consistently observed and in good agreement with a hypothesis of azimuthal anisotropy due to transverse anisotropy with a horizontal axis in the upper mantle beneath the receivers we have designed an inversion method which takes advantage of observations made simultaneously at different azimuths and which permits us to obtain estimates of the direction of fast axis of anisotropy as well as the time delay between the orthogonal quasi shear waves in general the directions of fast velocity obtained both for stations around the atlantic and around the pacific appear to be related to directions of past and present plate motions

toward a unified conceptual framework for shear sense indicators abstract the growing lexicon for shear sense indicators has created a need for a unified conceptual system of classification many common shear structures can be described by linear combinations of two kinematic variables which quantify the relative importance of objects vs foliations in controlling the shear zone velocity field

lithosphere asthenosphere interaction at the southeastern carpathian arc bend implications for anisotropy abstract the vrancea region in the southeastern carpathians romania represents a unique case among the seismic areas in the world taking into account the extreme concentration and persistence of seismicity and the tectonic stress field subduction in a post collisional phase is still active in a narrow area located at the sharp bend of the mountain belt our goal is to show that the particular shape of the shear wave splitting can be interpreted in the light of the decoupling and slab retreat processes which hypothetically induce a specific configuration of the upper mantle flow shear wave splitting of sks phases shows a relatively coherent pattern outside the epicentral area suggesting a prominent ne sw anisotropy in agreement with previous estimations performed in central and eastern europe and following the trends of the deformation field as outlined by the gps measurements a clear change is pointed out inside the vrancea area where strike parallel polarization is emphasized toward the nw wedge side the polarization turns to a strike perpendicular direction in agreement to an upwelling asthenospheric flow in the back arc region i e polarization aligned to the local strike of the slab these shear wave splitting attributes are not consistent with conventional models of 2 d mantle flow near subduction zones nor with a sub vertical down dipping flow driven by the sinking of the slab they correlate well with lateral inhomogeneities outlined by the tomography image heat flow seismic wave attenuation and thermal field we suggest that the eastward slab retreat and decoupling between the underlying asthenosphere and the slab itself have induced strike parallel mantle flow likely favoring detachment of the slab along the arcuate mountain belt these processes are directly related to the strong anisotropy observed in the se carpathians the anisotropy and gps data suggest a strong coupling of the surface and mantle processes

upper mantle anisotropy beneath the altai sayan region of central asia abstract the altai sayan region of central asia is actively deforming despite its being located several thousands of kilometers away from the collisional front between india and eurasia to add constraints to the role of the upper mantle in this type of tectonic environment we analyzed intermediate period analogue records of sks and skks to determine the state of mantle anisotropy in this region we find that for all stations located in actively deforming areas the fast direction of anisotropy correlates well with indicators of cenozoic to the present day deformation and correlates with older structures only when they happen to align with younger ones the general east northeast trend of the fast direction of anisotropy in active regions also aligns with the principle extensional strain axis determined from earthquake moment tensors at one station nvs located outside of any actively deforming region the n s fast direction may correspond to the long wavelength strain field of the mantle beneath much of siberia these correlations along with the size of the delay times 1 2 s suggest that the anisotropy in the upper mantle beneath the altai sayan is responding to recent tectonic activity

evidence for general instability of past climate from a 250 kyr ice core record recent results1 2 from two ice cores drilled in central greenland have revealed large abrupt climate changes of at least regional extent during the late stages of the last glaciation suggesting that climate in the north atlantic region is able to reorganize itself rapidly perhaps even within a few decades here we present a detailed stable isotope record for the full length of the greenland ice core project summit ice core extending over the past 250 kyr according to a calculated timescale we find that climate instability was not confined to the last glaciation but appears also to have been marked during the last interglacial as explored more fully in a companion paper3 and during the previous saale holstein glacial cycle this is in contrast with the extreme stability of the holocene suggesting that recent climate stability may be the exception rather than the rule the last interglacial seems to have lasted longer than is implied by the deep sea specmap record4 in agreement with other land based observations5 6 we suggest that climate instability in the early part of the last interglacial may have delayed the melting of the saalean ice sheets in america and eurasia perhaps accounting for this discrepancy

structural analysis of mylonitic rocks in the cougar creek complex oregon idaho using the porphyroclast hyperbolic distribution method and potential use of sc type extensional shear bands as quantitative vorticity indicators abstract mylonitic rocks of the cougar creek complex of northeastern oregon and west central idaho provide an opportunity to document the deformational structures produced during general non coaxial shear within quartz feldspar mylonites and to explore the potential role of sc type extensional shear bands in vorticity analysis well developed feldspar porphyroclasts within six mylonite zones were utilized to estimate bulk kinematic vorticity w k using the porphyroclast hyperbolic distribution phd method w k values for the cougar creek mylonites range from w k 0 26 to w k 0 37 synthetic and antithetic shear band inclinations were measured relative to observed shear zone boundaries within five mylonite zones with estimated w k values and compared to the non coaxial flow field geometries and eigenvector orientations in each mylonite zone synthetic sc type shear band populations exhibit a range of inclination with maximum inclination lying approximately parallel to the acute bisector ab of the eigenvectors similarly antithetic shear band populations show a range of inclination near the obtuse bisector ob of the eigenvectors we infer that sc type extensional shear bands form initially parallel to ab and ob and rotate towards the flow plane with progressive deformation decreasing their inclination relative to the shear zone boundary ab and ob have significance in the strain field in that they represent orientations of maximum angular strain rate thus planes perpendicular to ab and ob are mechanically favorable for small zones of localized simple shear shear bands within the heterogeneous bulk strain of the mylonite orientation analysis of populations of sc type shear bands may provide a direct quantitative means of estimating w k

sedimentology seismic facies and stratigraphy of a holocene spit platform complex interpreted from high resolution shallow seismics lysegrund southern kattegat denmark abstract eighty kilometres of high resolution seismic profile data 8 km km 2 were collected in the lysegrund area southern kattegat denmark to reconstruct the seismic stratigraphy of a holocene spit platform complex comparison of two sets of seismic data shows a significant difference in reflection pattern by using lap style analyses four holocene units were recognised in boomer profiles 0 8 2 0 khz they are closely examined in this paper and their geometry is illustrated in a series of isopach maps drawn to understand the development of the deposit in time and space three vibra cores provide the stratigraphic control and demonstrate the presence of three lithofacies with gradational boundaries in the interval that correlates with the three upper boomer units the three lithofacies are part of a single lithofacies succession in contrast to the boomer profiles the subbottom profiles 3 5 khz demonstrate continuous accretion surfaces within the lithofacies succession comparisons of the boomer and subbottom profile data therefore indicate that the three boomer units are genetically coupled and that there are no significant time gaps between units the three boomer units are interpreted to represent a spit platform complex that developed in three phases during a general rapid rise of relative sea level 10 mm a under conditions of excess sediment supply the source materials were mobilised from glacial fluvial sediments in a headland west of and close to the spit platform during phase 1 spit development occurred in shallow water this acted as a core to the development of a spit platform during phase 2 that consisted of three seismic facies identifiable on 3 5 khz subbottom profiles during phase 3 true foresets and bottomsets developed growth of the platform surface kept pace with sea level rise and the entire spit platform complex formed in less than a thousand years focusing on differences in the seismic data helps avoid pitfalls in choosing methods to interpret data the closely spaced seismic line net forms the basis of a 3d dynamic model of the spit platform that resembles the model of meistrell meistrell f j 1972 the split platform concept laboratory observations of spit development in schwartz m l ed spits and bars dowden hutchinson and ross stroudsberg pp 225 283

rheology microstructure and crystallographic preferred orientation of matrix containing a dispersed second phase insight from experimentally deformed ice abstract we utilize in situ neutron diffraction to continuously track the average grain size and crystal preferred orientation cpo development in ice during uniaxial compression of two phase and pure ice samples two phase samples are composed of ice matrix and 20 vol of second phases of two types 1 rheologically soft platy graphite and 2 rigid rhomb shaped calcite the samples were tested at 10 c below the ice melting point ambient pressures and two strain rates 1 10 5 and 2 5 10 6 s 1 to 10 and 20 strain the final cpo in the ice matrix where second phases are present is significantly weaker and ice grain size is smaller than in an ice only sample the microstructural and rheological data point to dislocation creep as the dominant deformation regime the evolution and final strength of the cpo in ice depend on the efficiency of the recrystallization processes namely grain boundary migration and nucleation these processes are markedly influenced by the strength shape and grain size of the second phase in addition cpo development in ice is further accentuated by strain partitioning into the soft second phase and the transfer of stress onto the rigid second phase

late pleistocene holocene sediments on the spanish continental shelves model for very high resolution sequence stratigraphy abstract sequence stratigraphy analysis of high resolution seismic profiles geopulse uniboom and 3 5 khz of late pleistocene holocene sediments has been carried out on five sectors of the spanish continental margin four types of depositional settings are distinguished in these sectors 1 low subsident ramps alboran margin cadiz gulf 2 high subsident 2m kyr ramps alicante valencia 3 ria type morphology on the atlantic passive margin ria de muros and 4 fault scarp morphology systems with subsidence balearic margin a type 1 sequence is interpreted in all these sectors being composed of lowstand systems tract transgressive systems tract and highstand systems tract this conforms to the basic concepts of sequence stratigraphy and each systems tract correlates with a particular part of the last eustatic hemicycle characteristic shelf features such as terraces terraces with beach deposits and progradational sediment wedges evidence a complex stacking of lesser sub sequences in all the systems tracts which must be related to very short period sea level stillstands and fall we propose a very high resolution sequence stratigraphy model in which the last sea level hemicycle is punctuated by p cycles 4500 years which give rise to the neo glacial events h cycles 2200 950 years and c cycles 500 50 years these cycles interact with each other thus establishing the placing of the high and low sea levels this attention to detail 1 explains sedimentary evolution on both the shelf and upper slope during late pleistocene holocene time 2 illustrates some departures from the classical sequence stratigraphy model and 3 also demonstrates that the late pleistocene holocene eustatic curve is not one simple transgression but is modulated by three differing period cycle groups below the milankovitch band our model is delimited by fluctuating sea level during pleistocene holocene times such features should be identifiable on any continental margin however localized features occur due to subsidence and continental shelf morphology which determ ine the location and depth of sedimentary bodies generated in each eustatic cycle

facies and cycle architecture of a pleistocene marine terrace crotone southern italy a sedimentary response to late quaternary high frequency glacio eustatic changes abstract cyclic late pleistocene shallow marine deposits such as those forming the sedimentary cover of some marine terraces allow a detailed study of the architecture of nearshore to offshore cycles deposited under the influence of high amplitude glacio eustatic changes the capo colonna marine terrace located near crotone southern italy is composed of two cycles recording a low frequency retrogradational trend which is thought to be the result of a generalized base level rise during a late pleistocene interglacial stage superimposed on regional uplift cycles of the capo colonna marine terrace are composed of coarse grained lags siliciclastic shoreface deposits and mostly carbonate shelf deposits and their general stratigraphic architecture evidences relatively thin transgressive and thick regressive intervals the latter can be top truncated due to wave ravinement during a subsequent erosional transgression the architectural style of the capo colonna marine terrace cycles is thought to be linked to very rapid base level rises related to the late pleistocene high amplitude glacio eustatic changes climatic variations controlling the sediment supply rate are considered less effective in the present context present results allow a comparison with other cyclic successions developed under icehouse climatic regimes showing a discrete variability in their stratal architecture

a late pleistocene coarse grained spit platform sequence in northern jylland denmark several well preserved late pleistocene spit systems occur uplifted in northern jylland denmark their present day morphological expression allows detailed study of spit growth patterns while the internal sedimentological organisation can be examined in a series of pits distributed along the length of the spits two characteristic vertical sequences are recognized in the systems the first sequence i consists of a giant scale cross bedded foreset unit overlain by topset and beach units while the second sequence ii consists of the foreset unit overlain by bar trough and beach units the two sequence types pass laterally into each other with a short overlap zone they can be interpreted in terms of meistrell s 1966 1972 model for spit platform growth based on scaled wave tank experiments the giant scale cross bedded unit corresponds to prograding of a coarse grained subaqueous spit platform while the topset bar trough and beach units reflect the growth of the subaerial spit the alternation between sequence i and ii reflects the inversely related growth of the spit and platform structures when the rate of subaqueous platform progradation declines the subaerial spit grows uniformly and when the platform progrades uniformly spit growth declines the model is probably only valid for relatively coarse grained systems because only these deposits would have a relatively steep front the water depth in which the spit system progrades and thus bottom topography determines the thickness of the giant scale cross bedded foreset unit because the water depth over the top of the platform is relatively constant if the water is less than a few metres deep the spit platform is not developed as seen where the late pleistocene spit systems prograded over elevations of the sea bottom conversely the correct recognition of spit platform sequences allows precise determination of sea level and water depth at the time of formation finally the model adds one further mode of formation of giant scale cross bedding to those already known from fluvial transverse lateral and point bars subtidal sand waves and gilbert deltas

sequence concepts at seismic and outcrop scale the distinction between physical and conceptual stratigraphic surfaces abstract the sequence stratigraphic terms maximum flooding surface and downlap surface as currently applied are ambiguous examples of these intra sequence surfaces are summarised from high frequency mid pleistocene sequences and from a cretaceous recent seismic megasequence both from new zealand at any one locality a mid pleistocene sequence contains up to four stratal discontinuities in ascending order the sequence boundary ravinement surface local flooding surface and downlap surface these physical surfaces which occur in outcrop are regionally diachronous and should be differentiated from theoretical isochronous horizons such as the time of maximum flooding horizon corresponding to maximum shoreline transgression and the time of peak eustatic or local relative sea level horizons corresponding to the highpoint of the eustatic and relative sea level cycles respectively in seismic studies the boundary between the transgressive and highstand systems tracts is usually located at the downlap surface on the basis of a major thermo tectonic sea level cycle in the canterbury basin it is shown that the downlap surface is not a single regional surface and that the change in slope associated with toes of successive prograding clinoforms rises in stratigraphic height basinwards the downlap surface therefore does not usually coincide with the maximum flooding horizon in plio pleistocene cyclothems a discrete unit the mid cycle shellbed straddles the contact between the transgressive and highstand systems tracts this unit might be classified within its own systems tract the condensed section systems tract csst alternatively the position of the boundary between the transgressive and highstand systems tracts can remain unspecified or unknowable

upper mantle stratification by p and s receiver functions summary seismic stratification of the upper mantle is investigated by applying two complementary techniques to the records of the graefenberg array in southern germany the anisotropic p receiver function technique kosarev et al 1984 vinnik montagner 1996 is modified by using summary seismic events instead of individual events and different weighting functions instead of the same function for the harmonic angular analysis of the sv and t components of the pds phases the summary events provide better separation of the second azimuthal harmonic than the individual events the parameters of the second harmonics of sv and t thus evaluated should be similar if they reflect the effects of azimuthal anisotropy this can be used as a criterion to identify the anisotropy to detect the sdp phases and their azimuthal variations caused by azimuthal anisotropy we have developed a stacking technique which can be termed the s receiver function technique it includes axis rotation to separate interfering p and s arrivals determination of the principal m component of the s wave motion deconvolution of the p components of many recordings by their respective m components and stacking of the deconvolved p components with weights depending on the level of noise and the angle between the m direction and the backazimuth of the event both techniques yield consistent results for the graefenberg array as indicated by the p receiver functions the upper layer of the mantle between the moho and 80 km depth is anisotropic with dvs vs around 0 03 and the fast direction close to 20 clockwise from north the fast direction of anisotropy below this layer is around 110 the boundary between the upper and the lower anisotropic layers is manifested by the detectable pds and sdp converted phases shear wave splitting in sks is strongly dominated by azimuthal anisotropy in the lower layer asthenosphere

strain probe best fitting a homogeneous strain to the motions of scattered points abstract in laboratory experiments or e g in studies of glacier motion one sometime wants to estimate a finite strain from images or surveys of scattered marker points taken at successive times similarly crustal geodetic strain can be estimated by measuring velocities of geodetic stations the strain probe presented here is a simple formula that calculates a best fit strain from the motions of n marker points distributed over an area or a volume and monitored in a cartesian reference frame specifically it is the product of two 2 2 or 3 3 in 3 d symmetric matrices whose components are populated from the known positions and the measured displacements of the markers two examples implemented in excel workbooks illustrate how to combine the strain probe with the processing of the data and of its results speck motions in a means urai see through experiment are an example of a finite strain calculation published geodetic site velocities 120 stations in central anatolia are an example of infinitesimal strain

anatomy of a late pleistocene clinoformal sedimentary body le castella calabria southern italy a case of prograding spit system abstract the le castella marine terrace is the smallest and youngest terrace of the crotone area southern italy and formed after a rapid marine ingression due to a glacio eustatic rise outpacing the regional uplift of the area the most prominent feature of the terrace deposits is a seaward accreting clinoform about 10 m thick inferred to be formed during forced regressive conditions this prograding body is mostly composed of bioclastic material and shows an internal complexity consisting of alternating oblique and sigmoid elementary units inferred to be produced mainly by changes of accommodation development foreset avalancing was due to sediment accumulation by gravity flow processes while topsets were characterized by the migration of medium to large scale dunes showing a unimodal palaeocurrent pattern oblique with respect to the dip direction of the large scale clinoform foresets the le castella clinoform starts to develop from a topographic step on the basement due to tectonics which also controlled the palaeoshoreline trend the recognized stratigraphic and facies architectures the palaeocurrent pattern and the inferred palaeogeographic setting during deposition all suggest that the le castella clinoform is an example of spit system attached to the mainland and accreted due to longshore transport the present example contributes to establish criteria allowing the recognition of ancient spit systems which still are poorly known and rarely documented in the pre quaternary geological record

synkinematic microscopy of transparent polycrystals abstract deformation of weak polycrystalline materials in thin section on the stage of a petrographic microscope offers insight into the origin of optical microstructures similar to microstructures in naturally deformed rocks sample materials used to date include several soft minerals ice carnallite bischofite nitratite and various organic plastic materials they can be simple sheared or pure sheared at temperatures to 300 c at a variety of strain rates using relatively simple and inexpensive apparatus the complete microstructural evolution can be recorded photographically along with the complete kinematic history research applications have focussed on dynamic recrystallization and progress has been made towards understanding how the average grain size is maintained constant in steady state recrystallization flow records have been obtained of the development of various crystal plastic microstructures and of lattice reorientation trajectories during flow teaching applications have begun to be developed and several videotapes are available future technical developments are expected to permit stress measurement or control during experiments and synkinematic recording of lattice reorientation numerous research areas invite attention these include investigation of the microstructural developments that precede faulting the behaviour of deforming crystal melt systems and the behaviour of dynamically reactive multi phase systems