Kinematic Events Research Articles

Magnetic susceptibility and partial anhysteretic remanence anisotropies in the magnetite-bearing granite pluton of Tourão, NE Brazil

Rock magnetism and magnetic fabric studies were performed in the Tourão granite (western part of Seridó belt, NE Brazil). This pluton (350 km 2) is composed of K-rich calc-alkalic monzogranites and was emplaced between a set of NE- and E-trending dextral strike–slip shear zones. Electronic and optical microscopy, thermomagnetic curves, hysteresis data and coercivity spectra revealed that magnetite (fine- and coarse-grained) is the unique ferromagnetic mineral in these rocks. Anisotropy of low-field magnetic susceptibility (AMS) was measured in 83 sites, and for many sites from central and southern parts of the intrusive body a large scatter was noticed. Anisotropy of partial anhysteretic remanence (pAAR) was determined for 29 sites in the 0–50 mT (pAAR 0–50) and 19 sites in the 50–90 mT (pAAR 50–90) windows to isolate the fabric contribution of the remanence bearing grains (magnetite). In most sites AMS is dominantly carried by magnetite, whereas in some sites the paramagnetic contribution exceeds 60% of the bulk susceptibility. The pAAR 0–50 is assumed to be related to coarse-grained early crystallized magnetites, while the pAAR 50–90 is interpreted as due to fine needle-shaped magnetites hosted in biotites. The combined analysis of these magnetic techniques permits interpretation in terms of fabric formation in the Tourão granite and the inference that at least two successive kinematic events were recorded in this intrusive body devoid of any solid-state deformation overprint. The AMS and pAAR 0–50 fabrics for most of the sites correlate with the early NNE-trending magmatic fabric, whereas pAAR 50–90 reveals a different fabric, probably related to late partitioning of magmatic straining along the E-trending shear zones. In the southern part of the body, a completely different pAAR 0–50 fabric is correlated with the late intrusion of charnockite stocks.

Critical kinematic events occurring in the trunk during walking

The purpose of this study was to systematically assess three-dimensional trunk kinematics during level walking in normal subjects, to establish a preliminary baseline for comparison to future research in gait analysis, and aid in the identification of pathological gait. Seventeen volunteers between the ages of 20 and 50, who met criteria for normal subjects, participated. Trunk kinematic data were collected using an optoelectronic technique. An ensemble average of trunk kinematic data in each of the cardinal planes was plotted in degrees of motion versus percentage of gait cycle. A distinct pattern of trunk kinematics during gait was found in this study. These data, along with information from past researchers, were used to identify the critical trunk kinematic events which occur during walking.

Mechanics of ventilation in swellsharks, Cephaloscyllium ventriosum (Scyliorhinidae).

A simple two-pump model has served to describe the mechanics of ventilation in cartilaginous and bony fishes since the pioneering work of G. M. Hughes. A hallmark of this model is that water flow over the gills is continuous. Studies of feeding kinematics in the swellshark Cephaloscyllium ventriosum, however, suggested that a flow reversal occurred during prey capture and transport. Given that feeding is often considered to be simply an exaggeration of the kinematic events performed during respiration, I investigated whether flow reversals are potentially present during respiration. Pressure and impedance data were coupled with kinematic data from high-speed video footage and dye studies and used to infer patterns of water flow through the heads of respiring swellsharks. Swellsharks were implanted with pressure transducers to determine the pattern and magnitude of pressures generated within the buccal and parabranchial (gill) cavities during respiration. Pressure traces revealed extended periods of pressure reversal during the respiratory cycle. Further, impedance data suggested that pressures within the buccal and parabranchial cavities were not generated by the cyclic opening and closing of the jaws and gills in the manner previously suggested by Hughes. Thus, the classic model needs to be re-evaluated to determine its general applicability. Two alternative models for pressure patterns and their mechanism of generation during respiration are provided. The first depicts a double-reversal scenario common in the swellshark whereby pressures are reversed following both of the pump stages (the suction pump and the pressure pump) rather than after the pressure-pump stage only. The second model describes a scenario in which the suction pump is insufficient for generating a positive pressure differential across the gills; thus, a pressure reversal persists throughout this phase of respiration. Kinematic analysis based on high-speed video footage and dye studies, however, suggested that during respiration, as opposed to feeding, distinct flow reversals do not result from the pressure reversals. Thus, water is probably pooling around the gill filaments during the long periods of pressure reversal.

Motion percepts: “Sense specific,” “kinematic,” or . . . ?

In line with my model of object motion perception (Wertheim 1994) and in contradistinction to what Stoffregen (1994) states, Sauvan's data suggest that percepts of motion are not sense specific. It is here argued that percepts of object- or self-motion are neither sense specific nor do they necessarily stem from what Stoffregen calls “kinematic events.” Stoffregen's error is in believing that we can only perceive object- or self-motion relative to other objects, which implies a failure to realise that percepts of absolute object- or self-motion in space (relative to the earth's surface) do exist as well, even when the earth's surface itself is not perceived.

The role of visual feedback of hand position in the control of manual prehension.

Although it is obvious that vision plays a primary role in reaching and grasping objects, the sources of the visual information used in programming and controlling various aspects of these movements is still being investigated. One source of visual information is feedback relating to the characteristics of the reach itself for example, the speed and trajectory of the moving limb and the change in the posture of the hand and fingers. The present study selectively eliminated this source of visual information by blocking the subject's view of the reaching limb with an opaque barrier while still enabling subjects to view the goal object. Thus, a direct comparison was made between standard (closed-loop) and object-only (open-loop) visual-feedback conditions in a situation in which the light levels and contrast between an object and its surroundings were equivalent in both viewing conditions. Reach duration was longer with proportionate increases in both the acceleration and deceleration phases when visual feedback of the reaching limb was prevented. Maximum grip aperture and the proportion of movement time at which it occurred were the same in both conditions. Thus, in contrast to previous studies that did not employ constant light levels across closed- and open-loop reaching conditions, a dissociation was found between the spatial and temporal dimensions of grip formation. It appears that the posture of the hand can be programmed without visual feedback of the hand--presumably via a combination of visual information about the goal object and proprioceptive feedback (and/or efference copy). Nevertheless, maximum grip aperture (like the kinematic markers examined in the transport component) was also delayed when visual feedback of the reaching limb was selectively prevented. In other words, the relative timing of kinematic events was essentially unchanged, reflecting perhaps a tight coupling between the transport and grip components.

The charged trigger system of NA48 at CERN

The NA48 charged trigger is a mixed hardware and software real-time processing system intended to detect the interesting configurations of K0 charged decays. It achieves real-time event building, track reconstruction and kinematics computation on drift chamber data at an event rate of 100kHz and within a maximum decision latency of 100μs. The system uses data driven, FPGA-based coordinate builders, a hardware event builder based on a crossbar switch, and a farm of up to 16 event processors for its software part. It has been installed and operated at CERN since 1995. After a description of the constraints and architecture of the various subsystems, the paper gives an account of the results and performance of the system based on the 1996/1997 runs. More specifically, the replacement of the present DSP-based implementation of the processing farm by RISC processors will be discussed.

The charged trigger system of NA48 at CERN

The NA48 charged trigger is a mixed hardware and software real time processing system intended to detect the interesting configurations of K/sup 0/ charged decays. It achieves real-time event building, track reconstruction and kinematics computation on drift chamber data at an event rate of 100 kHz and within a maximum decision latency of 100 /spl mu/s. The system uses data driven, FPGA-based coordinate builders, a hardware event builder based on a crossbar switch, and a farm of up to 16 event processors for its software part. It has been installed and operated at CERN since 1995. After a description of the constraints and architecture of the various subsystems, the paper will give an account of the results and performance of the system based on the 1996/1997 runs. More specifically, the replacement of the present DSP-based implementation of the processing farm by RISC processors will be discussed.

Kinematic, Aerodynamic and Anatomical Mechanisms in the Slow, Maneuvering Flight of Pigeons

ABSTRACT A high-speed (200 Hz) infrared video system was used in a three-dimensional analysis of pigeon wing and body kinematics to determine the aerodynamic and anatomical mechanisms they use to produce force asymmetries to effect a turn during slow (3 m s−1) flight. Contrary to our expectations, pigeons used downstroke velocity asymmetries, rather than angle of attack or surface area asymmetries, to produce the disparities in force needed for directional changes. To produce a bank, a velocity asymmetry is created early in the downstroke and, in the majority of cases, then reversed at the end of the same downstroke, thus arresting the rolling angular momentum. When the velocity asymmetry was not reversed at the end of downstroke, the arresting force asymmetry was produced during upstroke, with velocity asymmetries creating disparate drag forces on the wings. Rather than using subtle aerodynamic variables to produce subtle downstroke force asymmetries, pigeons constantly adjust their position using a series of large alternating and opposing forces during downstroke and upstroke. Thus, a pigeon creates a precise ‘average’ body position (e.g. bank angle) and flight path by producing a series of rapidly oscillating movements. Although the primary locomotor event (downstroke) is saltatory, maneuvering during slow flight should be considered as a product of nearly continuous, juxtaposed force generation throughout the wingbeat cycle. Further, viewing upstroke as more than stereotypical, symmetrical wing recovery alters the evolutionary and functional context of investigations into the musculoskeletal mechanisms and the associated neural control involved in this unique kinematic event.

Direct Dating of Fabric Forming Events: Resolving a Continuous Record of Alpine Tectonic Events in the Aegean Region

4~ laserprobe dating allows direct dating of discrete deformational and kinematic events, as long as; regional thermal conditions are well constrained, deformational fabrics and kinematics are carefully characterized, and the fabric forming mineral used for dating can be related to the right fabric and the right metamorphic assemblage. Considering the metamorphic stability field and the closure temperature ranges for the main K-bearing minerals that can be used for 4~ age dating (Fig. 1), it is shown that two temperature windows exist at which white mica and hornblende respectively may (re-)crystallize below their closure temperature ranges, which is of interest as discrete fabric forming events might be directly datable. In this study 4~ laserprobe dating has been applied to white mica bearing fabrics in greenschist and blueschist facies settings, because: Geodynamisch Onderzoeksinstituut, Faculteit Aardwetenschappen, Universiteit Utrecht

Kinematic data on major Variscan strike-slip faults and shear zones in the Polish Sudetes, northeast Bohemian Massif

The still highly disputable terrane boundaries in the Sudetic segment of the Variscan belt mostly seem to follow major strike-slip faults and shear zones. Their kinematics, expected to place important constraints on the regional structural models, is discussed in some detail. The most conspicuous is the WNW–ESE Intra-Sudetic Fault Zone, separating several different structural units of the West Sudetes. It showed ductile dextral activity and, probably, displacement magnitude of the order of tens to hundreds kilometres, during late Devonian(?) to early Carboniferous times. In the late Carboniferous (to early Permian?), the sense of motion on the Intra-Sudetic Fault was reversed in a semi-brittle to brittle regime, with the left-lateral offset on the fault amounting to single kilometres. The north–south trending Niemcza and north-east–southwest Skrzynka shear zones are left-lateral, ductile features in the eastern part of the West Sudetes. Similarly oriented (northeast–southwest to NNE–SSW) regional size shear zones of as yet undetermined kinematics were discovered in boreholes under Cenozoic cover in the eastern part of the Sudetic foreland (the Niedźwiedź and Nysa-Brzeg shear zones). One of these is expected to represent the northern continuation of the major Stare Mesto Shear Zone in the Czech Republic, separating the geologically different units of the West and East Sudetes. The Rudawy Janowickie Metamorphic Unit, assumed in some reconstructions to comprise a mostly strike-slip terrane boundary, is characterized by ductile fabric developed in a thrusting regime, modified by a superimposed normal-slip extensional deformation. Thrusting-related deformational fabric was locally reoriented prior to the extensional event and shows present-day strike-slip kinematics in one of the sub-units. The Sudetic Boundary Fault, although prominent in the recent structure and topography of the region, was not active as a Variscan strike-slip fault zone. The reported data emphasize the importance of syn-orogenic strike-slip tectonics in the Sudetes. The recognized shear sense is compatible with a strike-slip model of the northeast margin of the Bohemian Massif, in which the Kaczawa and Góry Sowie Units underwent late Devonian–early Carboniferous southeastward long-distance displacement along the Intra-Sudetic Fault Zone from their hypothetical original position within the Northern Phyllite Zone and the Mid-German Crystalline High of the German Variscides, respectively, and were juxtaposed with units of different provenance southwest of the fault. The Intra-Sudetic Fault Zone, together with the Elbe Fault Zone further south, were subsequently cut in the east and their eastern segments were displaced and removed by the younger, early to late Carboniferous, NNE–SSW trending, transpressional Moldanubian–Stare Mesto Shear Zone.

Kinematic and electromyographic analysis of steady pectoral fin swimming in the surfperches

The musculoskeletal mechanism of pectoral fin propulsion was investigated in representatives of the two subfamilies of the Embiotocidae (surfperches). Kinematic and electromyographic records of steady swimming by the open-water cruiser Amphistichus rhodoterus and the benthic maneuverer Embiotoca lateralis were compared at 80 % of the species' respective pectoral­caudal gait transition speeds. Synchronized records of fin movement and the intensity of pectoral muscle activity allowed previous hypotheses of muscle function, based on anatomical lines of action, to be tested. Divisions of the pectoral musculature inserting on the central and trailing- edge fin rays serve simple functions of abduction and adduction. Muscles controlling the fin's leading edge, by contrast, play more complex roles during the fin stroke, including deceleration of the fin at the downstroke­upstroke transition and rotation of the adducted fin during the non-propulsive period between fin beats. In spite of their phylogenetic and ecological divergence, the surfperches exhibit a number of mechanistic similarities which probably characterize the family. The timings of kinematic events and the maximal excursions of the fin tip, as well as the temporal order of muscle activation and the time to peak activity, are largely conserved. The predominant dorsoventral component of fin movement during the stride is consistent with a lift-based mechanism of propulsion. E. lateralis exhibits a greater anteroposterior range of motion and a more continuous period of fine motor control of the fin than A. rhodoterus, differences which may correspond to the species' respective capacities for maneuvering. Mechanistic variation in the family is associated with rather minor structural differences (in fin shape and fin base orientation). Owing to the similar functional demands placed on the pectoral fins of many fishes, it is probable that the mechanistic details of embiotociform swimming are widely distributed within the Perciformes.

Rotational reflectance of dispersed vitrinite from the Arkoma basin

Rotational reflectance of dispersed vitrinite provides superior documentation of thermal maturity and a capability for interpreting relative timing between thermal and kinematic events in Arkoma Basin strata characterized by vitrinite reflectances up to 5%. Rotational reflectance ( R rot) is a more precise and less ambiguous index of thermal maturity than maximum ( R′ max), minimum ( R′ min), and random ( R ran) reflectance. Vitrinite reflectance anisotropy becomes sufficiently large to be measurable (using a microscope equipped with an automated rotating polarizer) at ≈2% R rot and increases following a power function with increasing thermal maturity. Rotational reflectance data can be used to infer the shape of the vitrinite reflectance indicating surface (i.e. indicatrix) and, in turn, to enhance interpretations of the timing between thermal maxima and compressional tectonic events. Data from three wells in the Arkoma Basin-Ouachita frontal thrust belt are used as examples. The absence of offsets in measured R rot across thrust faults combined with a predominance of uniaxial vitrinite in the thrust faulted part of the section suggest thermal maximum postdated thrust faulting in the western Ouachita frontal thrust belt of Oklahoma. In contrast, the general absence of offsets in measured R rot across thrust faults combined with a predominance of biaxial vitrinite in the thrust faulted part of the section suggest that the thermal maximum was coeval with thrust faulting in the eastern Ouachita frontal thrust belt of Arkansas. The presence of biaxial vitrinite in an allochthonous section and uniaxial vitrinite in an underlying, autochthonous section suggests that the thermal maximum was coeval with listric thrust faulting in the central Arkoma Basin of Oklahoma, and that rotational reflectance data can be used as a strain indicator to detect subtle décollement zones.

Hercynian tectonics in the Pyrenees: a new view based on structural observations around the Bassie`s granite pluton

The structural study of the metasedimentary rocks surrounding the Bassie`s granite pluton allows definition of the succession and kinematics of the Hercynian tectonic events in this part of the Pyrenees, and supports a model of syntectonic emplacement of the pluton. The following sequence of events has been identified: (i) an early phase of N-S compression, essentially resulting in southwards thrusting; (ii) emplacement of the granite body along a NE-SW sinistral strike-slip shear zone which could be a late effect of the first phase; (iii) a major dextral and transpressive phase, responsible for themain fold structures trending, on average, N100 °, and following a sigmoidal pattern around the granite body. This succession of events and their kinematics could be extended to the whole Hercynian basement of the Pyrenees.

New Data on Axial Locomotion in Fishes: How Speed Affects Diversity of Kinematics and Motor Patterns

Synopsis. Despite considerable recent progress in understanding the func? tion of the axial muscles and skeleton in fishes, generalizing from these results has been hindered by the great phylogenetic diversity of taxa, the lack of quantitative morphometric data on axial musculoskeletal structure, and limited analysis of the Ml range of locomotor behaviors exhibited within any one taxon. This paper reviews novel results from our studies of two taxa within a single monophyletic clade, the sunfish family Centrarchidae. Integrated analyses of lateral displacement, lateral bending, and axial muscle activity reveal widespread effects of swimming speed both within a particular mode of swimming and among different behavioral modes. The longitudinal position along the body of the fish also commonly affects kinematics, muscle activity and the timing of electromyograms (EMGs) relative to kinematics. EMGs and kinematic events propagate from head to tail for both steady and kick and glide swimming. In contrast, during the escape response, the onset of EMGs forms a standing wave pattern, whereas kinematic events are propagated. Several novel features of the axial motor pattern are summarized for the kick and glide mode of unsteady swimming. For example, the onset of white fiber EMGs lags significantly behind that of the red fibers at the same longitudinal position, and red fibers are inactivated at higher unsteady swim? ming speeds. Muscle activity propagates posteriorly via the sequential acti? vation of myomeres, but there are statistically significant differences in the timing of EMGs from the contractile tissue opposite a single vertebra. During relatively slow kick and glide swimming, the extreme dorsal and ventral portions of myomeres are not active. Estimates of the longitudinal extent of the fish with simultaneous muscle activity indicate that EMGs from an in? dividual myomere usually have temporal overlap with more than 20 neighboring myomeres on the same side of the fish. Consequently, the functional units for axial locomotion of fishes do not correspond simply to the anatom? ical units of individual myomeres. Rather the in vivo motor pattern is a primary determinant of the functional units involved in swimming.

The design of a cryogenic dark matter detector based on the detection of the recoil direction of target nuclei

Abstract We discuss the design of a cryogenic detector for a WIMP dark matter search based on single crystal absorbers and using Series Arrays of Superconducting Tunnel Junctions (SASTJs). The distribution of recoil vectors of target nuclei from WIMP interactions are affected by the motion of the laboratory through the dark matter halo. The angular distribution of recoil directions is skewed due to the motion of the solar system around the galaxy and is modulated by the diurnal and annual rotation of the earth. We discuss the kinematics of the recoil events and how a directional signal might be identified in our cryogenic detectors using the fast response of SASTJs to the ballistic phonons arising in the absorber from WIMP interactions. We consider how the anisotropy of a dark matter recoil distribution can be used to place statistical limits on its component relative to the isotropic background signal. We also consider how the dark matter limit is altered if only the axis of the nuclear recoil, rather than the full recoil direction is available. We also briefly consider the effect of phonon focusing within single crystal absorbers. Focusing will modulate strongly the signal detected by the SASTJs, on the crystal surface, as the position of the interaction within the crystal varies. A comparison is made between the behaviour of phonons in strongly focusing crystals, such as Nb, Si and LiF, and their near isotropic propagation in BaF2.

A preliminary seismic interpretation of an area with extensive Tertiary basalts offshore central West Greenland

A seismic and geological interpretation of the area between latitudes 67°30'N and 73°N offshore West Greenland, was completed in 1995 and has been published as an Open File Series report (Whittaker, 1995). The area is characterised by extensive Early Tertiary basalts which are the seaward extension of the plateau basalts exposed in the Disko - Nuussuaq - Svartenhuk Halvø area onshore (Clarke & Pedersen, 1976). These basalts present special problems in the processing and interpretation of seismic data. The interpretation incorporates all the seismic data acquired prior to the 1995 field season, inc1uding those lines acquired during the first phase of exploration in the 1970s. Ties to two of the exploration wells drilled offshore southem West Greenland have led to a greater understanding of the timing and kinematics of teetonie events during the Tertiary period; such events are not recorded in the onshore area. The area is considered to have significant exploration potential and warrants additional studies to determine the thickness of the basalt formation in the area.

Particle physics research for first year students

The first physics laboratory course for undergraduate students at the University of Oslo is briefly presented. The last part of the course introduces the students to currently ongoing research projects at the department of physics. An exercise in practical data analysis relating to a high energy physics experiment at the LEP accelerator at CERN is discussed in some detail. The selection of events for luminosity determination is discussed. The students study event kinematics and detector performance. The entire exercise is based on real data.Sammendrag. Det første laboratoriekurset for laveregradsstudenter ved Universitetet i Oslo blir kort presentert. Den siste delen av kurset lar studentene komme i kontakt med pågående forskningsprosjekter ved Fysisk Institutt. En øvelse i praktisk data-analyse i forbindelse med et høyenergifysikk-eksperiment ved LEP-akseleratoren ved CERN diskuteres i noen detalj. Utvelgelse av hendelser for luminositetsbestemmelse blir diskutert. Studentene studerer kinematikk og detektoregenskaper. Hele øvelsen er basert på reelle data.

Measurement of the left-right forward-backward asymmetry for charm quarks with D*+ and D+ mesons.

We present a direct measurement of {ital A}{sub {ital c}}=2{ital v}{sub {ital c}}{ital a}{sub {ital c}}/({ital v}{sup 2}{sub {ital c}}+{ital a}{sup 2}{sub {ital c}}) from the left-right forward-backward asymmetry of {ital D}{sup *}+ and {ital D}{sup +} mesons in {ital Z}{sup 0} events produced with the longitudinally polarized SLAC Linear Collider beam. These {ital Z}{sup 0}{r_arrow}{ital c} over bar events are tagged on the basis of event kinematics and decay topology from a sample of hadronic {ital Z}{sup 0} decays recorded by the SLAC Large Detector. We measure {ital A}{sup 0}{sub {ital c}} = 0.73 {plus_minus} 0.22(stat) {plus_minus} 0.10(syst). {copyright} {ital 1995} {ital The} {ital American} {ital Physical} {ital Society}.

Young children's judgments of relative mass of two objects in a head-on-collision event.

The purpose in this study was to investigate the ability of young children to judge the relative mass of two objects depicted on a CRT monitor as colliding head-on with each other, and to determine which feature of a collision event they depend on for their judgments. In the first experiment it was shown that half of the 4-year-olds and most of the 5-year-olds and 6-year-olds consistently judged the slower object to be heavier when the velocities of the two objects before collision were the same and those after collision were different. In the second experiment young children's judgements of relative mass in noncollision events in which two objects only moved in opposite directions at different speeds were examined. Results showed that half of the 5-year-olds and most of the 6-year-olds tended to assume consistently that the slower object was heavier. However, the 4-year-olds did not show any clear tendency. The third experiment was planned to examine young children's judgments of relative mass in different collision events in which only the precollision velocities of two colliding objects were different: half of the 6-year-old children judged the slower object to be heavier, but the rest of them and half of the 5-year-old children consistently gave the opposite responses. These were based upon the delay between the starts of motion of the two objects. The 4-year-olds did not show any tendency, as in experiment 2. The results indicate that young children can specify the kinetic information about relative mass from the kinematics of collision events when viewing an appropriate collision event, and that both the precollision phase and the postcollision phase contribute to the judgement of relative mass.

Kinematics of Tertiary deformation in the basement-involved fold-thrust complex, western Nordenskiøld Land, Svalbard: tectonic implications based on fault-slip data analysis

Kinematic analysis based on the interpretation of small-scale fault and fold data supports a kinematic evolution history involving heterogeneous crustal shortening and uplift, and subsequent extension (collapse) for the major, west coast fold-thrust complex in western Nordenskiøld Land, Svalbard. This deformation can be divided into three main kinematic events. Stage 1 represents an early, distinctive, NNE-SSW-oriented contractional episode that generated layer parallel and low-angle thrusts and internal folds. Stage 1 structures (population 1) are arranged in an apparent en-échelon geometry and oblique direction relative to the major NNE-SSW-trending fold-thrust complex of stage 2 affinity. Stage 2 structures include ENE-verging chevron folds and steeply WSW-dipping thrusts and duplexes, that evolved during a progressive WSW-ENE-oriented contractional episode. Initial (pre-fold) stratal shortening (stage 2a) was followed by a continuous buildup of the fold-thrust complex and general crustal thickening (syn-fold, stage 2b), until a supercritical height/thickness was reached (post-fold, stage 2c). At this stage a change in the stress field caused failure of the fold-thrust complex, and continued NE-SW-directed shortening was accommodated as vertical strike-slip faults (population 2c). Late W-E-to WSW-ENE-directed extension, the stage 3 episode, was probably related to collapse of the overthickened stage 2 fold-thrust complex. The detailed reconstruction of kinematic events in western Nordenskiøld Land supports initial breakup of the Greenland-Svalbard area in Early Paleocene (?) times during dextral, NNE-SSW-directed transpression (stage 1). The major deformational episode (stage 2), probably of mid-Paleocene to Eocene age, was characterized by progressive WSW-ENE-directed shortening and was related to decoupled deformation where broad zones of convergent strain were linked to narrow strike-slip zones. This strain partitioning is considered to have begun when the Hornsund Fault Zone widened into and reactivated the basin-bounding faults of the Carboniferous St. Jonsfjorden Trough. The latest kinematic episode (stage 3) is likely of Eocene age, and may be ascribed to extensional collapse in the hinterland of the western Spitsbergen orogenic wedge within a regional, dextral transpressive setting.