curved vein fibres an alternative explanation abstract veins occurring at the edge of the dextral indian islands fault newfoundland are folded in response to a fault parallel ductile shear the veins which locally constitute a penetrative fabric element at outcrop scale are composed mainly of calcite and have a narrow rim of quartz and chlorite both the calcite and quartz are generally fibrous and lattice distortion in the calcite is not commensurate with the observed degree of fibre curvature this observation supports the popular view that curved fibres grow curved as they track the vein opening vector it is demonstrated however that the curvature in the material described here is due to deformation and that the lack of strong lattice distortion is due in part to polygonization and to recrystallization all observations are consistent with both the calcite and the quartz fibres having grown perpendicular to the vein walls the chlorite orientation is controlled by the orientation of mica grains in the country rock in some veins markers make it possible to define the net opening direction and in all examples it is demonstrated that the direction has not been tracked by the fibres since this conclusion may be more generally applicable caution should be exercised in interpreting kinematics on the basis of fibre geometry where vein density is high the veins and country rock screens separating them form a multilayer sequence that is folded into fairly harmonic folds the folds appear to have a cleavage transected relationship to the regional cleavage but the cleavage is shown to predate the folds

recent tectonics and slope failures in the western carpathians we describe several examples of recent tectonics and related slope failures from the western carpathians of slovakia the monitoring data confirm the idea of non uniform geodynamic behaviour of individual tectonic units as well as the idea that even an extremely low rate of displacement both in landslides and along active faults may endanger human life and property the crack gauge tm 71 is adopted as the monitoring device in our study and we confirm its reliability for measuring in plane displacements in severe conditions with a resolution of 0 1 mm year simple manipulation minimum maintenance requirements and reasonable price

flow perturbations a tool to study and characterize heterogeneous deformation the classification of the myriad of small scale structures that are used in tectonic analysis is presently based on their geometry which makes it difficult to discover transitions and groups amongst them an alternative would be to classify structures according to the flow type by which they form but this is difficult although most structures form by heterogeneous flow modelling studies are often focussed on bulk homogeneous flow since the mathematical treatment of heterogeneous flow is cumbersome also heterogeneous deformation patterns seem to occur in as many types as there are small scale structures this paper introduces the use of the geometry of flow perturbations to improve our understanding of heterogeneous flow and to allow classification of structures based on kinematics a flow perturbation is the deviation of a heterogeneous flow pattern from the background homogeneous flow perturbation patterns can be visualised as open or closed loops of vectors which occur in pairs rows or groups of four they usually cross cut rheological interfaces and can be subdivided into those that cross interfaces twice or four times most geological structures belong to the first group while initiating buckle folds belong to the second group q 2005 elsevier ltd all rights reserved

vorticity determination distribution partitioning and the heterogeneity and non steadiness of natural deformations abstract an investigation on vorticity in general heterogeneous and non steady flows is presented the bulk vorticity of a flow is solely determined by the imposed boundary conditions and it exerts no constraints on local flow the distribution of bulk vorticity in different rheological domains and the partitioning of the distributed vorticity into shear induced vorticity and spin are both time dependent this indicates that heterogeneous flows are inevitably non steady in a quantitative example it is demonstrated that even though the imposed boundary movement is a constant simple shear local flow can be non steady spinning and non coaxial super simple shear flow with internal kinematic vorticity number greater than i occurs but the finite strain does not necessarily pulsate the geological implications of this investigation are discussed the significance of heterogeneity and non steadiness in natural deformations are emphasized it is concluded that vorticity distribution and partitioning is the link between different scale structures the internal kinematic vorticity number is not a criterion of finite strain oscillation

flow and finite deformation of surface elements in three dimensional homogeneous progressive deformations rocks are heterogeneous materials deformation structures and fabrics in the ductile lithosphere can result from the history of the three dimensional flow field or the progressive deformation of some rheologically distinct elements embedded in the 3d flow field or a combination of both the flow and progressive deformation of a rheologically distinct element is generally non steady even if the hosting 3d flow field is steady vorticity decomposition is the key to following the progressive history of the deformation of specific elements a general theoretical background to the problem is presented flow and progressive deformation of surface and layer like elements in 3d homogeneous flows are investigated specifically analytical procedures to calculate the sectional vorticity number and the sectional dilatancy number on a general section in a 3d flow field are introduced the theoretical analysis is applied to various examples of sectional flow embedded in different types of 3d homogeneous and steady flow fields implications of this investigation for kinematic analysis of natural rock deformation are discussed all types of material line histories are expected in sectional flows of layer like elements shortened boudins can be formed in a single progressive deformation in sequences of rocks with a well developed transposition foliation common in large scale high strain zones each layer unit may have undergone a unique deformation history during its rotation to the final shear zone boundary parallel orientation in kinematic analysis of such areas it is important to ascribe the correct kinematic significance to structural associations and fabrics

landslide dynamics from high resolution aerial photographs a case study from the western carpathians slovakia abstract the ubietova landslide is one of the largest landslide events in the central slovakia neogene volcanic field area its present morphology resulted from several reactivation events the latest one took place in 1977 we applied archive digital photogrammetry to build the historical topography of the landslide area and reconstructed its evolution from 1969 to 1998 at approximately decadal scale four sets of aerial photos of the area taken in 1969 scale 1 16 000 1977 scale 1 14 000 1988 scale 1 17 000 and 1998 scale 1 20 000 were processed using a digital photogrammetric workstation elevation data were extracted from all the photo sets then four high resolution digital elevation models dems were generated and compared particular interest was placed on quantification of vertical ground displacements and volumetric mass redistribution both of them were calculated by subtracting two subsequent dems consequently distribution and temporal variation of the landslide activity over three decades are outlined through differential raster images differential dems and cross sections according to our results the 1977 reactivation event caused considerable vertical displacements up to 5 7 m in the peak areas of depletion and accumulation zones accordingly large volumes of material 148 000 m3 84 000 m3 were redistributed during this event the dynamics of the 1977 reactivation event shows some specific features that are discussed within the broader context besides the new quantitative data reconstruction of 3d topography of the site before and after the 1977 reactivation brought geomorphic evidence that the area was affected by more than one landslide event in the past

geochronological constraints on the development of the cross lake greenstone belt northwest superior province manitoba recent 1 20 000 mapping combined with 11 age determinations from metavolcanic metaplutonic and metasedimentary rocks in the cross lake greenstone belt provide a framework for interpreting the stratigraphic structural intrusive and metamorphic evolution of the belt these data in combination with u pb ages from adjacent granitoid domains are used to model a cratonizing event in the northwest superior province the cross lake greenstone belt is made up of three distinct unconformable groups of supracrustal rocks i the pipestone lake group 2760 ma a thick sequence of pillowed and massive tholeiitic basalt flows and related high level gabbros inter preted as a back arc spreading sequence ii the gunpoint group 2730 ma a fining upward sequence of clastic sediments interbedded with rhyodacitic fragmental volcanic rocks and iii the cross lake group 2710 ma a fining upward fluvial marine clastic sedimentary sequence with shoshonitic volcanic rocks near the top deposited in a restricte

characteristics and dynamic origin of the large scale jiaoluotage ductile compressional zone in the eastern tianshan mountains china abstract the jiaoluotage ductile compressional zone jdcz in the eastern tianshan mountains china developed in volcanic and sedimentary rocks that were deposited in a carboniferous back arc basin situated between the jungar plate and middle tianshan terrane the ductile compressional zone 500 km long and 20 50 km wide consists of a number of east trending vertical foliation zones that display an augen geometry in plan view and a fan like geometry in transverse profiles ductile compressional deformation has produced pervasive foliation radial stretching lineations contemporaneous folds and various macroscopic to microscopic symmetric structures within the jdcz rotations of most clasts and porphyroclasts are bidirectional the preferred orientation patterns of the optical axes of calcite and quartz display axial or orthorhombic symmetry three kinds of strain patterns have been determined in the jdcz apparent flattening plane strain and apparent constriction the overall strain character of the jdcz is cream cake style the volcanic and sedimentary rocks within the jdcz were metamorphosed into greenschist facies with temperature of 400 600 c and pressure of 300 400 mpa development of the jdcz is interpreted as due to n s coaxial compression caused by the collision between the tarim plate and the middle tianshan arc jiaoluotage basin jungar plate system during the permian between 270 and 290 ma

a tectonic pressure pulse and increased geodynamic activity recorded from the long term monitoring of faults in europe abstract this paper presents the results of a long term monitoring study undertaken during the period 2002 2007 the study recorded the displacement of various widely distributed tectonic structures along the generally aseismic bohemian massif czech republic and specifically along the sudeten marginal fault zone the derived results were compared with data recorded over the same time period in the upper rhine graben germany central apennines italy and the gulf of corinth greece it is clear that a tectonic pressure pulse initiated a period of increased geodynamic activity across central and southern europe during the course of our monitoring within the bohemian massif the pressure pulse was first recorded in mid 2003 and the ensuing period of increased geodynamic activity lasted for nearly three years this period is associated with compression along the sudeten marginal fault zone the southern flank was repeatedly downthrust beneath the northern flank which caused the latter to continually uplift and subside the period of increased geodynamic activity was terminated by two strong local earthquakes consequently it is considered that this period induced earthquake activity within the bohemian massif when taken together the presented data provides robust evidence for the reconfiguration of stress and strain relationships within central and southern europe whilst it is possible that tectonic activity in the alps produced a north verging pressure pulse that affected central europe e g in the bohemian massif and upper rhine graben it cannot account for the pressure pulse recognised to the south e g in the central apennines and the gulf of corinth due to the predominance of vertical movements it is suggested that this reconfiguration results from deep seated processes within the lithosphere asthenosphere however the influence of horizontal movements transmitted from the compressional zone between africa and europe cannot be discounted

reference frame angular momentum and porphyroblast rotation abstract rotation of small rigid objects in a deforming ductile matrix can produce two different types of microstructure a shape fabric due to alignment of the principal axes of a population of elongate objects and the inclusion trail microstructure preserved in syntectonic porphyroblasts we use numerical modeling to show that inclusion trails of elongate porphyroblasts are expected to be extremely complex in contrast snowball garnets are readily interpretable but misuse of reference frame and kinematic misconceptions have obfuscated the discussion on the formation of porphyroblast inclusion trails in general and snowball garnet inclusion trails in particular we clarify this point models for snowball garnet formation that are based on the notion of garnets being irrotational with respect to the earth can be rejected on a geometrical and kinematic basis further the notion that rigid objects embedded in a deforming ductile matrix generally do not rotate is unsound it violates the fundamental physical law of balance of angular momentum

sustainable transpression an examination of strain and kinematics in deforming zones with migrating boundaries most orogenic belts owe their development to oblique convergence and commonly have many orogen parallel transpressional high strain zones to constrain the tectonic history of orogenic belts by structural and fabric analysis of rocks it is desirable to understand quantitatively the relationship between the boundary conditions and the resulting strain distribution and kinematics in these zones most current models for transpression assume homogeneous deformation confined by boundaries that are fixed to material planes this creates a strain compatibility problem at the margins of the active deforming zone and also requires that the strain rate normal to the zone boundaries increase to implausibly high values soon after the onset of oblique convergence transpressional motion the latter contradicts with the observation that transpressional motion can be sustained throughout an orogeny the assumption that zone boundaries are fixed to material planes is unrealistic the outstanding problems of current transpressional models are resolved in this paper by allowing the zone boundaries to migrate through the rock material the consequence of zone boundary migration for the strain field and kinematics within a transpressional high strain zone is investigated mathematically the implications of the modeling for fabric interpretation are discussed the modeling makes general predictions consistent with observed planar and linear fabric patterns in natural transpressional high strain zones it predicts that foliations in transpressional high strain zones are subparallel to the zone boundaries regardless of variation in the imposed boundary conditions lineations cluster along the great circle girdle subparallel to the average foliation the spread of the lineations may vary from point maxima to complete girdles

a microstructural dry snow metamorphism model for kinetic crystal growth historically dry snow metamorphism has been classified by the thermal environment and thermodynamic processes in a snowpack snow experiencing predominantly macroscopic isothermal conditions develops different microstructure than snow subjected to large temperature gradients as such much previous research has been categorized by and limited to specific thermal conditions the current research expands a generalized approach for the movement of heat and mass to include a snow crystal kinetic growth model an existing spiral defect propagation theory for kinetic growth on simple faceted geometry is utilized primary crystal habit as a function of temperature is incorporated a model of heat and mass transfer through an ice and pore structure is coupled with phase change thermodynamics during kinetic growth a kinetic growth microstructure model is developed and integrated into heat and mass transfer representations which are solved using finite difference techniques the kinetic morphology model approximates frequently observed hopper type crystals the snow microstructure is allowed to change at every step resulting in a transient description of kinetic growth metamorphism variable kinetic growth rates are demonstrated based on temperature and on crystallographic orientation relative to a temperature gradient crystals preferentially aligned with the temperature gradient have significantly higher growth rates supporting previous observations of predominant crystal habits developing under temperature gradient conditions grain size dispersion increase with time is demonstrated and supported experimentally in the literature a dominant grain growth theory based on crystallographic orientation that has been previously postulated is supported a broad range of metamorphic geometric parameters and thermal conditions may now be simulated with a single model

control of slope deformations in high seismic area results from the gulf of corinth observatory site greece abstract the northern coast of the peloponnesus greece is characterized by high seismic activity related to the gulf of corinth opening with an extension rate of 16 mm y 1 studies presented in this paper focus on the characterization of links between tectonic and slope deformations on the panagopoula slope located on the southern coast the approach is centred on qualitative and quantitative data acquisition based on geological and geomorphological investigations geophysical imagery by electrical resistivity tomography and slope displacement monitoring firstly we highlight two different types of slope deformation on panagopoula a superficial landslide affecting weathered limestone and a large scale deformation without global failure expressed in the field tectonic features play a major role in these two dynamic processes taking into account the strong geometrical link between the inherited fractures and gravitational scarps mapped in the field secondly the displacements survey network distributed on both sides of a significant fault crossing the slope allows the quantification of slope displacements underlying two components i a gravitational sliding n010 along the slope and ii a supposed tectonic component n240

tectonic strain changes affecting the development of deep seated gravitational slope deformations in the bohemian massif and outer western carpathians abstract this paper describes a pair of intensively studied deep seated gravitational slope deformations from the czech republic structural geological mapping and the interrogation of high resolution lidar dems have been used to reassess the extent of each slope deformation and to obtain new information about their surface morphologies electrical resistivity tomography has been used to image the subsurface structures while rod dilatometers and permanently installed mechanical extensometers have been used to define their kinematic behaviour dilatometric measurements from across a fissure the edge of the mu sk hill dsgsd show that the progressive trend has been interspersed by five periods of movement acceleration since monitoring began in 1990 while extensometric measurements from across a second fissure about 50 m from the edge of the plateau show that this discontinuity was affected by an significant period of extension from 2004 to 2006 and a significant period of compression from 2006 to 2008 these data demonstrate that the mu sk hill dsgsd is characterised by the lateral spreading of rigid sandstone blocks across a plastic marl formation at the edge of p ihrazy plateau extensometric measurements from the kn hyn mountain dsgsd show that a fault located at a depth of about 25 m below the surface is characterised by progressive dilation whereas a fault located at a depth of about 57 5 m below the surface is characterised by episodic vertical dip slip displacements both faults are affected by horizontal dextral strike slip displacements these data demonstrate that the kn hyn mountain dsgsd is characterised by translational rocksliding associated with the neotectonic uplift of the outer western carpathians the presented kinematic data have been compared to records of precipitation groundwater level earthquakes and strain changes measured by the fault displacement monitoring network eu tecnet strain changes induced by the widespread redistribution of stress through the crustal appear to represent an important and hitherto underappreciated geomorphological process affecting the development of the slope deformations at mu sk hill and kn hyn mountain future research will focus discovering whether this finding holds true for other deep seated gravitational slope deformations in different geomorphological and geological settings

partitioning of non coaxiality in deforming layered rock masses abstract partitioning of non coaxiality and other flow parameters in deforming layered rock masses with nearly incompressible newtonian rheology is examined in two dimensions by the finite element method the results show that layers with viscosity contrast in suitable orientation deform by different and even by a reverse sense of non coaxiality this remarkable partitioning of non coaxiality is due to a large rotation rate of instantaneous stretching axes in a heterogeneous body as a result of geometry changing through deformation rather than through rotation of material lines

reconstruction of deformation and flow parameters from deformed vein sets abstract in any homogeneously deformed material sets of material lines with a similar stretch history occupy sectors with a scale and orientation that depend on finite strain area change rate and vorticity of the parent flow if the size and shape of these material line sectors are known they can be used to determine the sense of shear and to calculate deformation and flow parameters even if actual stretches along material lines are unknown in rocks which have undergone near homogeneous deformation on a large scale the orientation of sets of boudinaged folded and folded boudinaged or boudinaged folded veins can be used for such calculations a general theoretical background to the problem is presented and a mohr circle construction to carry out the deformation and flow analysis is introduced among other statements the theory predicts that shortened or folded boudins must develop in non coaxial monophase deformation with considerable area change in the plane of observation or in polyphase deformation

the partitioning of deformation in flowing rock masses abstract most geological structures owe their development to heterogeneous and or non steady flow flow partitioning refers to the division of the instantaneous velocity field into components related to translation strain and rotation flow partitioning during the development of a geological structure usually changes with time and different histories of flow are involved at different points in the developing structure heterogeneity leads to the development of flow domains with different characteristics notably the degree of non coaxiality of deformation and different partitionings of the rotational component of flow into shear induced vorticity and spin during non steady flow there is often continual repartitioning of vorticity between the spin and shear induced components spin is an important aspect of flow leading to the development of structure this paper discusses the partitioning of deformation in a flowing rock mass coaxial flow tends to occur in isotropic materials in regions near weakly constrained boundaries non coaxial flow is favoured by suitably oriented material anisotropy and or the presence of well defined boundary constraints involving parallel relative displacements a developing anisotropy e g a crystallographic fabric in a shear zone can induce a change from coaxial to non coaxial flow other effects are related to the scale of approximation for example bulk shear induced vorticity can be locally converted to spin flow in the crust and mantle of the earth produces geological structures on all scales and involves many different types of rheological response the factors that affect flow partitioning e g spin versus non coaxial deformation are therefore of interest

the largest prehistoric landslide in northwestern slovakia chronological constraints of the kykula long runout landslide and related dammed lakes abstract this study deals with the chronology of the largest long runout landslide in the northwesterrn part of the western flysch carpathians kysucke beskydy mts slovakia despite the impossibility of using direct radiocarbon dating method time constraints for the evolution of the landslide were determined on the basis of the dating of various sedimentological geomorphological elements situated on and adjacent to the landslide body the results show that the landslide evolved between 10 3 and 9 0 ka 14 c bp i e in the wider transitional phase between the late glacial lg and the holocene the main mass movement activity took place at the turn of the younger dryas preboreal chronozones whereas retrogressive activity continued up to the preboreal boreal transition radiocarbon dating together with pollen analysis and sedimentology of landslide dammed palaeolakes and colluvial peat bogs revealed almost continuous holocene palaeogeographical records between 10 3 and 3 3 ka 14 c bp periods of enhanced sediment supply to the reservoirs in 9 9 9 0 8 4 8 2 6 9 6 5 and 4 5 ka 14 c bp correlate well with palaeogeomorphic and palaeohydrological records from nearby polish carpathians the study confirms that the lg holocene transition represented a favourable period for the evolution of large landslides not only in glaciated high mountain areas but also in medium high mountains of central europe

high strain zones a unified model abstract where a shear zone is bounded by undeformed wall rocks and there is no volume change the deformation path within the zone on the bulk scale approximates a simple shear where the zone boundaries are stretched and the shear direction between the two boundaries is parallel to one of the principal stretching directions of the boundaries the deformation path within the zone is not a simple shear but still has monoclinic symmetry both simple shear and general monoclinic deformation paths should be regarded as special cases in nature because generally not only are the zone boundaries stretched but also the shear is oblique to the principal stretching directions of the boundaries in this general case the deformation path is triclinic we establish a model which includes this general case also taking into consideration volume change five independent parameters are required to characterize the rate of deformation of the flow four are sufficient to characterize the flow kinematics the model is generally triclinic and orthorhombic and monoclinic deformations are subgroups by varying the values of the characterizing parameters the various types of high strain zones can be represented the kinematics of flow within such zones and the accumulated finite deformation geometry are investigated many field observations such as for example lineations in transcurrent shear zones that vary between vertical and horizontal cleavage transected folds and the absence of sheath folds in some shear zones where folds have been significantly rotated can sometimes be better interpreted in the context of our general model

a fundamental problem with the kinematic interpretation of geological structures abstract non steady flows are ubiquitous in nature not only do imposed boundary conditions vary with time and rock rheology change during the course of deformation but also deformation is generally heterogeneous and all of these conditions lead to non steady flow histories in modern kinematic analysis flow apophyses the instantaneous stretching axes and the vorticity vector collectively referred to as the eigen directions of deformation are used in place of bruno sander s kinematic axes for deformation with a steady flow history this practice is well justified and has led to great advances in structural geology but for non steady flow histories the geometrical relationships among eigen directions flow pattern vary with time this makes it inappropriate to correlate an association of structures and fabrics with certain time invariant flow patterns and hence raises the question how should we interpret geological structures and fabrics kinematically without the assumption of homogeneous and steady deformation we suggest that the answer lies primarily in forward modeling of deformation based on a knowledge of rock properties